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PLOS One logoLink to PLOS One
. 2021 Jul 16;16(7):e0254271. doi: 10.1371/journal.pone.0254271

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients undergoing non-cardiac surgery: A systematic review with meta-analysis and trial sequential analysis

Min Shui 1,#, Ziyi Xue 1,#, Xiaolei Miao 1, Changwei Wei 1,*, Anshi Wu 1,*
Editor: Martina Crivellari2
PMCID: PMC8284831  PMID: 34270584

Abstract

Background

Intravenous and inhalational agents are commonly used in general anesthesia. However, it is still controversial which technique is superior for the quality of postoperative recovery. This meta-analysis aimed at comparing impact of total intravenous anesthesia (TIVA) versus inhalational maintenance of anesthesia on the quality of recovery in patients undergoing non-cardiac surgery.

Methods

We systematically searched EMBASE, PubMed, and Cochrane library for randomized controlled trials (RCTs), with no language or publication status restriction. Two authors independently performed data extraction and assessed risk of bias. The outcomes were expressed as mean difference (MD) with 95% confidence interval (CI) based on a random-effect model. We performed trial sequential analysis (TSA) for total QoR-40 scores and calculated the required information size (RIS) to correct the increased type I error.

Results

A total of 156 records were identified, and 9 RCTs consisting of 922 patients were reviewed and included in the meta-analysis. It revealed a significant increase in total QoR-40 score on the day of surgery with TIVA (MD, 5.91 points; 95% CI, 2.14 to 9.68 points; P = 0.002; I2 = 0.0%). The main improvement was in four dimensions, including “physical comfort”, “emotional status”, “psychological support” and “physical independence”. There was no significant difference between groups in total QoR-40 score (P = 0.120) or scores of each dimension on POD1. The TSA showed that the estimated required information size for total QoR-40 scores was not surpassed by recovered evidence in our meta-analysis. And the adjusted Z-curves did not cross the conventional boundary and the TSA monitoring boundary.

Conclusion

Low-certainty evidence suggests that propofol-based TIVA may improve the QoR-40 score on the day of surgery. But more evidence is needed for a firm conclusion and clinical significance.

1. Introduction

The requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide a fast and high quality of recovery. However, various factors impact quality of recovery of patients after surgery. These factors may lead to prolonged surgical recovery, delayed hospital discharge and increased cost.

Intravenous and inhalational agents are commonly used in general anesthesia. Several comparisons between the two anesthesia techniques have been conducted previously. Research has focused on the impact of total intravenous anesthesia (TIVA) versus inhalational anesthesia maintenance on outcomes such as emergence time, perioperative hemodynamic parameters, pain scores and analgesic consumption, postoperative nausea and vomiting (PONV), length of hospital stay and other adverse events [14]. There were also several meta-analyses on some of these topics [1,5,6]. In recent years, researchers have recognized the limitations of the fragmentary measures and started to focus on global assessment of recovery quality from different perspective [7].

The Quality of Recovery-40 (QoR-40) questionnaire is an extensively validated instrument to assess the quality of recovery after surgery and anesthesia [7,8]. The QoR-40 questionnaire is composed of 40 items and incorporates five dimensions of health: emotional state, physical comfort, psychological support, physical independence and pain. Each item is rated on a five-point Likert scale: none of the time, some of the time, usually, most of the time, and all of the time. The total score of QoR-40 questionnaire ranges from 40 (poorest quality of recovery) to 200 (best quality of recovery) [7,8].

Several studies reported that different anesthesia techniques affected the quality of postoperative recovery. But the results of these studies remain controversial. Some reported no significant statistical difference in QoR-40 score between the two anesthesia techniques [912]. Some reported that TIVA group had higher QoR-40 score [3,13]. Currently, there are no published systematic review or meta-analysis on this subject. We hypothesized that TIVA could improve the quality of postoperative recovery. This systematic review and meta-analysis aimed to identify the impact of TIVA compared to inhalational maintenance of anesthesia on the quality of recovery in adult patients undergoing non-cardiac surgery.

2. Materials and methods

This systematic review and meta-analysis adhered to the recommendations of the Cochrane Collaboration [14] and is reported per Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines [15]. The protocol was registered in the international prospective register of systematic reviews (PROSPERO) (CRD42020188757).

2.1. Search strategy and study selection

Three databases (Excerpta Medica database (EMBASE), PubMed, The Cochrane Central Register of Controlled Trials (CENTRAL)) were systematically searched for relevant trials from inception to June 19, 2020 with no language or publication status restriction. We also manually checked the reference lists of relevant papers to identify additional studies. Search terms included “anesthesia, intravenous”, “anesthesia, inhalation”, “anesthetics, inhalation”, “balanced anesthesia” and “quality of recovery” (S1 File).

We only included randomized controlled trials (RCTs) that compared the impact of propofol-based TIVA versus inhalational maintenance of anesthesia on the quality of recovery using the QoR-40. Inclusion criteria included: (1) Population: adult patients (age > 18 years) undergoing non-cardiac surgery under general anesthesia; (2) Intervention: propofol-based TIVA; (3) Comparator: inhalational maintenance of anesthesia; (4) Outcomes: (primary outcome) the total QoR-40 scores at different time point; scores of five dimensions, including physical comfort, emotional state, physical independence, psychological support and pain; (5) Study design: RCTs published in full-text versions. Studies with assessment tool for postoperative recovery quality other than QoR-40 were excluded.

2.2. Data extraction

We used reference management software (Medref 5.0) to collate the results of the searches and remove duplicates. Two authors (M.S. and Z.Y.X.) independently screened the results from titles and abstracts, and identified potentially relevant studies according to the eligibility criteria. The two authors independently performed reviews of full-text articles and data extraction. Any discrepancies were resolved by discussing with a third author (C.W.W.). We extracted information including study characteristics (publication year, design, setting and outcomes), participants (demographic characteristics, sample size and type of surgery), experimental intervention (induction technique, type of anesthetics, use of depth of anesthesia monitoring, administration regimen) and outcomes (total QoR-40 score, scores of each dimension, and time point). Means and standard deviations (SDs) were extracted from each study. If the data were normally distributed, median values and interquartile ranges were converted to means and SDs (http://www.math.hkbu.edu.hk/~tongt/papers/median2mean.html). We obtained estimated values from graphs or figures where numeric scores were not reported (https://apps.automeris.io/wpd/index.zh_CN.html). We contacted authors when information or results from the articles was insufficient.

2.3. Risk of bias and quality of evidence assessment

Two authors (M.S. and Z.Y.X.) independently assessed risk of bias using RevMan5.4 software, which assesses the following seven domains: Random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other bias. According to the Cochrane tool, each domain was classified as having low, unclear, or high risk of bias. We assessed publication bias through visual inspection of the funnel plot because of small number of included studies. The quality of evidence was classified using the GRADEpro software as high, moderate, low, or very low for each outcome based on five domains (the risk of bias, inconsistency, indirectness, imprecision, and publication bias) [16,17].

2.4. Statistical analyses

We used Review Manager 5.4 software for statistical analysis. All of the outcomes were quantitative variables and expressed as mean difference (MD) and standard deviation (SD) with respective 95% confidence interval (CI) based on a random-effect model (DL). A wide CI revealed imprecision in our results. Forest plots were used to illustrate the estimates of overall effects. P value < .05 was considered as statistically significant difference. Subgroup analysis for the outcomes was based on the time point of questionnaire assessment. Heterogeneity of each outcome was assessed by I2 statistic and the Chi-square test. I2 < 25%, 25% ≤ I2 < 50%, 50% ≤ I2 < 75%, and I2 ≥ 75% were considered as nil, mild, moderate and strong heterogeneity, respectively. In addition, we considered the point estimates and the overlap of CIs. We performed sensitivity analysis using a fixed-effect model. We also excluded each study sequentially to assess the impact of individual trials on the overall effect estimates. We performed trial sequential analysis (TSA) for total QoR-40 scores and calculated the required information size (RIS) to correct the increased type I error. The overall type I risk was set as 5%, with a power of 80%.

3. Results

3.1. Search results

A total of 156 articles were identified through the databases and other sources. After removing duplicate records, we screened the remaining 144 relevant publications. We obtained 19 full-text reports to assess eligibility (Fig 1) and excluded 10 references (3 conference paper, 1 duplicate data, 1 inadequate study design, 1 different intervention, 1 outcome using QoR-15 questionnaire, 1 lack of enough information, 2 ongoing studies). Finally, 9 randomized controlled trials (RCTs) consisting of 922 patients (462 in the TIVA groups and 460 in the inhalational maintenance groups) were reviewed [3,913,1820], and data from all of these were included in meta-analysis.

Fig 1. Study flow diagram.

Fig 1

3.2. Study characteristics

Of the included studies, 3 RCTs were performed in gynecological laparoscopies, 2 in otorhinolaryngology surgery, 1 in laparoscopic cholecystectomy, 1in thyroid surgery, 1 in vitrectomy and 1 in rhytidoplasty, respectively. All studies compared total intravenous anesthesia (TIVA) using propofol versus maintenance anesthesia using inhalational agents. All studies used intravenous agents during anesthesia induction in both groups. Four studies described propofol anesthesia using target-controlled infusion (TCI) [3,12,13,20]. Five studies compared TIVA versus maintenance using sevoflurane [912,18]. Three studies compared TIVA versus maintenance using desflurane [3,13,20]. One study did not report details of the inhalational agent [19]. Remifentanil was used in both groups during anesthesia maintenance except one study using ketamine in TIVA group [19]. Seven studies described monitoring of depth of anesthesia in both groups using of bispectral index (BIS). One study [19] described BIS monitoring only in TIVA group and the information was not available in another study (Table 1) [9].

Table 1. Characteristics of included studies.

Trial Country Setting ASA status Age: (yr ± SD) Gender: M/F Sample size BIS monitoring Surgery Anesthesia Outcomes
Inhalation TIVA
Li (2012) [18] China Inpatient I, II TIVA: 27.8±3.9
Inhalation: 28.2±4.1
TIVA: 0/30
Inhalation: 0/30
TIVA: 30
Inhalation: 30
Yes Gynecological laparoscopies Sevo + Remi Prop + Remi Total QoR-40 score at 24h after surgery
Mei (2014) [10] China Inpatient I, II TIVA: 28.6 ± 4.8
Inhalation: 28.1 ± 4.2
TIVA: 0/147
Inhalation: 0/148
TIVA:147
Inhalation: 148
Yes Gynecological laparoscopies Sevo + Remi Prop + Remi Total QoR-40 score at 24h after surgery
Jones (2015) [19] USA Outpatient NR Overall: 63.5 ± 6.8 TIVA: 0/15
Inhalation: 0/15
TIVA:15
Inhalation: 15
Only in TIVA group Rhytidoplasty NR Prop + Ketamine Total QoR-40 scores at PACU, and on POD1
Lee (2015) [13] Korea Inpatient I, II TIVA: 43.6 (23–60)
Inhalation: 40.0 (25–61)
TIVA: 0/38
Inhalation: 0/38
TIVA: 38
Inhalation: 38
Yes Thyroid surgery for neoplasm Des + Remi Prop (TCI) + Remi (TCI) Total and each dimension scores of QoR-40 on POD1 and POD2
Moro (2016) [9] Brazil Inpatient I, II TIVA: 37.9 ± 11.5
Inhalation: 39.3 ± 12.7
TIVA: 21/33
Inhalation: 25/31
TIVA: 54
Inhalation: 56
NR Otorhinolaryngological surgery Sevo + Remi Prop +Remi Total and each dimension scores of QoR-40 at 24h after surgery
De Oliveira (2017) [11] USA Outpatient I, II TIVA: 40.1 ± 11.5
Inhalation: 39.2 ± 12.4
TIVA: 0/37
Inhalation: 0/30
TIVA: 37
Inhalation: 30
Yes Gynecological laparoscopy Sevo + Remi Prop +Remi Total and each dimension scores of QoR-40 at 24h after surgery
Na (2018) [20] Korea Outpatient I, II, III TIVA: 59.0(51.0–64.0)
Inhalation: 60.0(50.0–70.0)
TIVA: 17/24
Inhalation: 19/23
TIVA: 41
Inhalation: 42
Yes Vitrectomy Des + Remi (TCI) Prop (TCI) + Remi (TCI) Total and each dimension scores of QoR-40 at 6h after surgery
Liu (2019) [3] China Inpatient I, II TIVA: 41.1 ± 12.6
Inhalation: 44.8 ± 1.43
TIVA: 25/15
Inhalation: 27/13
TIVA: 40
Inhalation: 40
Yes Endoscopic sinus surgery Des + Remi Prop (TCI) + Remi Total and each dimension scores of QoR-40 at 6h after surgery, and on POD1
De Carli (2020) [12] Brazil Inpatient I, II TIVA: 43.78±13.24
Inhalation: 43.95±11.43
TIVA: 0/60
Inhalation: 0/61
TIVA: 60
Inhalation: 61
Yes Laparoscopic cholecystectomy Sevo + Remi (TCI) Prop (TCI) + Remi (TCI) Total and each dimension scores of QoR-40 at 24h after surgery

Abbreviation: ASA, American Society of Anesthesiologists; BIS, bispectral index; Des, desflurane; NR, not reported; PACU, postanesthesia care unit; POD1, postoperative day 1; POD2, postoperative day 2; QoR-40, Quality of Recovery-40 questionnaire; Prop, propofol; Remi, remifentanil; Sevo, sevoflurane; SD, standard deviation; TCI, target-controlled infusion; TIVA, total intravenous anesthesia.

3.3. Risk of bias assessment

Overall, most studies were considered as low risk of bias (Fig 2). Only one study did not describe the details of random sequence generation [19]. Details of allocation concealment were not available in three studies [3,19,20]. There was no difference between the two reviewers (M.S. and Z.Y. X.) for assessment of risk of bias in any study.

Fig 2. Risk of bias summary: Review authors’ judgements about each risk of bias item for each included study.

Fig 2

3.4. Outcomes

Nine studies reported total QoR-40 scores. The questionnaire was assessed in postanesthesia care unit (PACU) in one study [19], two at 6 hours after surgery [3,20], five at 24 hours after surgery [912,18], three on postoperative day 1 (POD1) [3,13,19] and one on postoperative day 2 (POD2) [13], respectively. Data of three studies [3,19,20] were pooled in total QoR-40 score on the day of surgery. Data of eight studies [3,913,18,19] were pooled in total QoR-40 score on POD1. Six studies [3,9,1113,20] reported scores of five dimensions respectively. Data of five studies [3,9,1113] were pooled in scores in POD1.

Meta-analysis revealed a significant increase in total QoR-40 score on the day of surgery with TIVA compared to inhalational maintenance (MD, 5.91 points; 95% CI, 2.14 to 9.68 points; P = 0.002; I2 = 0.0%). There was no significant difference between groups in total QoR-40 score on POD1 (P = 0.120). Only one study reported the score on POD2, with no significant difference between groups in original data (P = 0.056) [13]. At 6 hours after surgery, TIVA group had higher scores of four dimensions except the “pain”. There was no significant difference between groups in score of each dimension on POD1(Figs 3 and 4).

Fig 3. Forest plots for total QoR-40 (A) and physical comfort (B) with TIVA versus inhalational maintenance.

Fig 3

CI, confidence interval; df, degrees of freedom; I2, heterogeneity index; IV, inverse variance; SD, standard deviation; QoR-40, Quality of Recovery-40 questionnaire; TIVA, total intravenous anesthesia.

Fig 4. Forest plots for emotional status (A) and psychological support (B) with TIVA versus inhalational maintenance.

Fig 4

CI, confidence interval; df, degrees of freedom; I2, heterogeneity index; IV, inverse variance; SD, standard deviation; QoR-40, Quality of Recovery-40 questionnaire; TIVA, total intravenous anesthesia.

We used the GRADE approach to judge the certainty of the evidence for total QoR-40 score on the day of surgery to be low. The quality of evidence for total QoR-40 score on POD1 was also classified as “low” (S2 and S3 Files).

3.5. Sensitivity analysis

We used the alternate meta-analytic effects model for these outcomes. We used a fixed-effect model which did not alter interpretation of all the results. We also conducted a sensitivity analysis to assess the impact of individual trials on the overall results. We excluded each study sequentially in subgroups on POD1. After removing one study (Lee 2015), the effect of physical comfort on POD1 remained the same but statistical heterogeneity was reduced (I2 = 0.0%). After removing one study (De Carli 2020), the effect of physical independence on POD1 altered, showing an increase in TIVA group (MD, 0.79 points; 95% CI, 0.02 to 1.56 points; P = 0.040; I2 = 59.0%). Other subgroup effects on POD1 did not alter.

3.6. Trial sequential analysis

All trials in each outcome were included in the Trial Sequential Analysis. The estimated RIS for total QoR-40 score on the day of surgery was 321, which was not surpassed by recovered evidence in our meta-analysis. The cumulative Z-curve for total QoR-40 score on the day of surgery crossed the TSA monitoring boundary for benefit (Fig 5A). But in penalized test, the adjusted Z-curve (Fig 5B, green line) did not cross the conventional boundary and the TSA monitoring boundary. It indicates that more evidence is needed to support high QoR-40 score on the day of surgery with TIVA.

Fig 5. Forest plots for physical independence (A) and pain (B) with TIVA versus inhalational maintenance.

Fig 5

CI, confidence interval; df, degrees of freedom; I2, heterogeneity index; IV, inverse variance; SD, standard deviation; QoR-40, Quality of Recovery-40 questionnaire; TIVA, total intravenous anesthesia.

In Fig 5C and 5D, the estimated RIS for total QoR-40 score on POD1 was 2787, and the Z-curve and adjusted Z-curve did not cross the conventional boundary and the TSA monitoring boundary, which also indicates that more evidence is needed for a firm conclusion.

4. Discussion

The systematic review and meta-analysis of nine RCTs evaluated the impact of TIVA versus inhalational maintenance on postoperative recovery quality using QoR-40 questionnaire. It revealed that TIVA might improve QoR-40 score on the day of surgery. The main improvement might be in four dimensions, including “physical comfort”, “emotional status”, “psychological support” and “physical independence”. No significant differences were found in QoR-40 scores on POD1. However, the Trial Sequential Analysis showed that the estimated RIS for total QoR-40 scores were not surpassed by recovered evidence in our meta-analysis. And the adjusted Z-curves did not cross the conventional boundary and the TSA monitoring boundary. Therefore, more evidence is needed for a firm conclusion, then we need to consider the clinical significance.

We used the GRADE approach and considered study limitations during “Risk of bias” assessment which may influence the certainty of the evidence for each outcome. We excluded one study [21] reporting total QoR-40 scores at 24 hours and 48 hours after surgery because there was no enough information to assess the biases. For the heterogeneities, we attempted to explore but were unable to identify potential explanations. Most of the qualities of evidence were categorized as low according to GRADE system. In sensitivity analysis, when we used a fixed-effect model or excluded each study sequentially, most interpretations of result did not alter. It revealed that the results were stable. The slight alteration appeared in the effects of physical independence on POD1. It might be due to the mean difference (95% CI) was too close to the invalid line. Though it detected a statistically significant increase in QoR score but not reflected the true clinical effect. A 0.79-points increase in TIVA group could not be considered clinically important.

Several comparisons between TIVA and inhalational maintenance of anesthesia have been conducted previously. Miller et al [1] published a meta-analysis about the postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery between the two anesthetic techniques. They found low-certainty evidence that maintenance with propofol-based TIVA may reduce postoperative cognitive dysfunction (POCD). However, the certainty of the evidence in incidences of postoperative delirium, mortality, or length of hospital stay was very low. Herling et al [5] conducted a meta-analysis and compared postoperative pain, postoperative nausea and vomiting (PONV), intraocular pressure (IOP) between the two anesthetic techniques for adults undergoing transabdominal robotic assisted laparoscopic surgery. Due to small number of studies, low-quality evidence suggested that TIVA reduced PONV and prevented an increase in IOP. Another meta-analysis [6] included coronary artery bypass grafting (CABG) patients revealed that there were no significant differences between the volatile anesthetics and TIVA groups in operative mortality, one-year mortality, or any of the postoperative safety outcomes.

These reviews demonstrate that different anesthetic techniques may affect postoperative recovery quality. The QoR-40 questionnaire is an overall assessment of postoperative recovery quality. The validity, reliability, responsiveness, acceptability, feasibility and cross-cultural adaptation have been confirmed [8]. It has been considered as an optimal tool to assess the quality of recovery. This is the first meta-analysis to address patient perception of postoperative quality of recovery of the two anesthetic techniques. But considering the results of trial sequential analysis, our outcomes need more evidence to be confirmed. Combined with previous similar meta-analyses, there is insufficient good quality evidence to conclude that TIVA is better than inhalational maintenance.

There were several limitations to this review: (1) The number of included studies was small (only 9 studies), and most studies had small sample sizes. (2) Different studies reported assessment in different time points, and three studies only reported the total QoR-40 scores, which reduced the number of studies in each subgroup. (3) Most types of surgery involved in these studies were minor surgeries, the results may be different in major surgeries which represent different nociceptive stimuli. (4) Participants of most studies were females, and the conclusion should be cautiously interpreted. (5) The ASA status, mean age, anesthetic management and monitoring of depth of anesthesia differed between the included studies. These differences may introduce inconsistency and reduce the overall applicability of the evidence.

In conclusion, we found low-certainty evidence that propofol-based TIVA might improve the QoR-40 score on the day of surgery. However, the trial sequential analysis showed that more evidence is needed for a firm conclusion and clinical significance.

Supporting information

S1 Checklist. PRISMA 2009 checklist.

(DOC)

S1 File. Search strategy.

(DOCX)

S2 File. SoF table JCA.

(DOCX)

S3 File. Funnel plot.

(DOCX)

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

The authors received no specific funding for this work.

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Decision Letter 0

Ahmed Negida

11 Jan 2021

PONE-D-20-35422

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients: a systematic review with meta-analysis and trial sequential analysis

PLOS ONE

Dear Dr. Wu,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Feb 22 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Ahmed Negida, MD

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors conducted a meta-analysis with trial sequential analysis to determine if total intravenous anesthesia was better than inhalation anesthetics in global recovery of patients. The clinical trials included in this meta-analysis used Quality of Recovery-40 score (QoR 40). The primary studies mostly involved mostly females, patients undergoing outpatient or ambulatory surgeries, intermediate to low risk surgeries. This is an important question for anesthesiologist, which to date has generated inconclusive results. This study attempts to combine results from nine studies and in essence reaches the same conclusion that the results are inconclusive.

General Comments

1. Though the total number of studies is 9 and n=922 patients, in reality there are two types of studies. One group of studies reporting results by six hours which has n of 193 and a second group reporting results by postoperative day one with an n= 839. The smaller group shows some benefit of total intravenous anesthesia, but the larger group does not show a difference in global recovery as reported by by QoR 40 score. Both groups do not achieve RIS threshold, so based on trial sequential analysis one can consider that the meta-analysis is under-powered to date.

2. All studies did not report all domains and sub-analysis of domains contain even less number of patients, which highlight another limitation of the study.

3. Trial Sequential analysis have their own limitations and it may be helpful for readers if the authors highlight those limitations (see Anaesthesia 2020, 75, 15-20) and explain how they have addressed some of the methodological limitation of the study.

4. This study provides a framework for future studies and I suspect, as with many meta-analyses, this is probably one of the initial ones in preparation for other analysis in future.

5. In my opinion considering that the studies showing benefit of total intravenous anesthesia are limited to six hours and have less than 200 patients, it would be advisable to tone down the benefit of total intravenous anesthesia versus inhalational anesthetic and highlight more than methodology, it's limitations and inconclusive nature of this question so far.

6. Another point to highlight is that the difference in absolute score is very small and its clinical significance is not clear.

Specific comments

P4 L71: What is meant by ‘quality of healthcare resources”?

P4 L81: …’discomfort’ sounds very informal. May be authors may consider ‘ …. various factors impact quality of recovery of patients after surgery. ‘

Figure 4: Post-operative Day 1 Physical independence

The total n should be 229 and 225. Please amend.

Reviewer #2: Title:

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients

Suggested: Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients

undergoing non-cardiac surgery.

Abstract:

Background: Second line: It is still controversial as to which technique

Suggested: It is still controversial which technique

Third line: This meta-analysis aimed to compare impact

Suggested: This meta-analysis aimed at comparing the impact

Methods:

Line 8/9: estimated required information size for total QoR-40 scores were not surpassed by

recovered evidence in our meta-analysis

Suggested: estimated required information size for total QoR-40 scores was not surpassed by

recovered evidence in our meta-analysis.

Page 5

All relevant data are within the manuscript and its Supporting Information files.

Suggested: All relevant data are within the manuscript and its supporting information files

Body of manuscript:

Line 25: It is still controversial as to which technique

Suggested: It is still controversial which technique

Line 26: This meta-analysis aimed to compare impact

Suggested: this meta-analysis aimed at comparing the impact

Line 69: The introduction mentioned (ambulatory anaesthesia) while the title is not about ambulatory

anaesthesia??!

Line 80: Please, omit reference number 7 and omit it from the references list as it is related to paediatric

anaesthesia and the scope of the manuscript is adult anaesthesia.

Line 127: Kindly, (Supplementary) to be written as (supplementary)

Line 132/133:

Here the 9 included studies used the intravenous induction route so the manuscript compares TIVA with

inhalational maintenance, so inhalational induction should be omitted.

Line 258: Kindly, change (Supplementary) to be (supplementary).

Discussion:

Lines 298/299:

more evidence is needed for a firm conclusion. Then we need to consider the clinical significance.

Suggested:

more evidence is needed for a firm conclusion, then we need to consider the clinical significance.

Line 309:

It might due to the mean difference (95% CI) too close to the invalid line

Suggested:

It might be due to the mean difference (95% CI) was too close to the invalid line

Line 333:

meta-analysis to address patient perception of postoperative recovery quality between the two anaesthetic

techniques.

Suggested:

meta-analysis to address patient perception of postoperative quality of recovery of the two anaesthetic

techniques.

Line 344:

participants of most studies were female

Suggested:

participants of most studies were females

Line 354:

And including these studies in future review updates would increase certainity of the effect.

Suggested:

And including these studies in future review updates will increase certainity of the effect.

References:

Reference number 19 link is invalid

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2021 Jul 16;16(7):e0254271. doi: 10.1371/journal.pone.0254271.r002

Author response to Decision Letter 0


4 Feb 2021

General Comments

1. Though the total number of studies is 9 and n=922 patients, in reality there are two types of studies. One group of studies reporting results by six hours which has n of 193 and a second group reporting results by postoperative day one with an n= 839. The smaller group shows some benefit of total intravenous anesthesia, but the larger group does not show a difference in global recovery as reported by by QoR 40 score. Both groups do not achieve RIS threshold, so based on trial sequential analysis one can consider that the meta-analysis is under-powered to date.

From reported evidence, our meta-analysis and trial sequential analysis, it is true that we couldn’t draw a firm conclusion, but it is real and it can provide reference for future research.

2. All studies did not report all domains and sub-analysis of domains contain even less number of patients, which highlight another limitation of the study.

We couldn’t agree more. These limitations were discussed in our manuscript.

3. Trial Sequential analysis have their own limitations and it may be helpful for readers if the authors highlight those limitations (see Anaesthesia 2020, 75, 15-20) and explain how they have addressed some of the methodological limitation of the study.

It is true that trial sequential analysis (TSA) have their own limitations. The TSA aimed to make the conclusion more reliable. And we complied with its rules. Thus, we think there may be no need to discuss the limitations of TSA in this meta-analysis.

4. This study provides a framework for future studies and I suspect, as with many meta-analyses, this is probably one of the initial ones in preparation for other analysis in future.

There seems no requirement for revision in this comment.

5. In my opinion considering that the studies showing benefit of total intravenous anesthesia are limited to six hours and have less than 200 patients, it would be advisable to tone down the benefit of total intravenous anesthesia versus inhalational anesthetic and highlight more than methodology, it's limitations and inconclusive nature of this question so far.

Our meta-analysis and TSA results clearly showed that current evidence couldn’t draw a firm conclusion. The current evidence does not support that total intravenous anesthesia is more advantageous.

6. Another point to highlight is that the difference in absolute score is very small and its clinical significance is not clear.

In our meta-analysis, trial sequential analysis showed that the difference in absolute score was not established, its clinical significance is certainly not clear. Thus, more evidence is needed. That was our conclusion.

Specific comments

P4 L71: What is meant by ‘quality of healthcare resources”?

We revised it in the manuscript.

P4 L81: …’discomfort’ sounds very informal. May be authors may consider ‘ …. various factors impact quality of recovery of patients after surgery. ‘

We revised it in the manuscript.

Figure 4: Post-operative Day 1 Physical independence

The total n should be 229 and 225. Please amend.

The study (De Carli 2020) was not estimable. Thus, the total number is right.

Reviewer #2: Title:

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients

Suggested: Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients

undergoing non-cardiac surgery.

We revised it in the manuscript.

Abstract:

Background: Second line: It is still controversial as to which technique

Suggested: It is still controversial which technique

We revised it in the manuscript.

Third line: This meta-analysis aimed to compare impact

Suggested: This meta-analysis aimed at comparing the impact

We revised it in the manuscript.

Methods:

Line 8/9: estimated required information size for total QoR-40 scores were not surpassed by

recovered evidence in our meta-analysis

Suggested: estimated required information size for total QoR-40 scores was not surpassed by

recovered evidence in our meta-analysis.

We revised it in the manuscript.

Page 5

All relevant data are within the manuscript and its Supporting Information files.

Suggested: All relevant data are within the manuscript and its supporting information files

We revised it in the manuscript.

Body of manuscript:

Line 25: It is still controversial as to which technique

Suggested: It is still controversial which technique

We revised it in the manuscript.

Line 26: This meta-analysis aimed to compare impact

Suggested: this meta-analysis aimed at comparing the impact

We revised it in the manuscript.

Line 69: The introduction mentioned (ambulatory anaesthesia) while the title is not about ambulatory

anaesthesia??!

Line 80: Please, omit reference number 7 and omit it from the references list as it is related to paediatric

anaesthesia and the scope of the manuscript is adult anaesthesia.

We revised it in the manuscript.

Line 127: Kindly, (Supplementary) to be written as (supplementary)

We revised it in the manuscript.

Line 132/133:

Here the 9 included studies used the intravenous induction route so the manuscript compares TIVA with

inhalational maintenance, so inhalational induction should be omitted.

We revised it in the manuscript.

Line 258: Kindly, change (Supplementary) to be (supplementary).

We revised it in the manuscript.

Discussion:

Lines 298/299:

more evidence is needed for a firm conclusion. Then we need to consider the clinical significance.

Suggested:

more evidence is needed for a firm conclusion, then we need to consider the clinical significance.

We revised it in the manuscript.

Line 309:

It might due to the mean difference (95% CI) too close to the invalid line

Suggested:

It might be due to the mean difference (95% CI) was too close to the invalid line

We revised it in the manuscript.

Line 333:

meta-analysis to address patient perception of postoperative recovery quality between the two anaesthetic

techniques.

Suggested:

meta-analysis to address patient perception of postoperative quality of recovery of the two anaesthetic

techniques.

We revised it in the manuscript.

Line 344:

participants of most studies were female

Suggested:

participants of most studies were females

We revised it in the manuscript.

Line 354:

And including these studies in future review updates would increase certainity of the effect.

Suggested:

And including these studies in future review updates will increase certainity of the effect.

We revised it in the manuscript.

References:

Reference number 19 link is invalid

We coped the link to the browser and opened it. It is right and valid.

Attachment

Submitted filename: Response to Reviewers.docx

Decision Letter 1

Ahmed Negida

30 Apr 2021

PONE-D-20-35422R1

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis

PLOS ONE

Dear Dr. Wu,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jun 14 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Ahmed Negida, MD

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

Reviewer #4: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Comments:

1- Line 69 and 70:

Requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide fast and high quality of recovery.

Suggested (kindly, observe that there are 2 suggested changes in the statement)

The requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide a fast and high quality of recovery.

2- Page 4 line 80 and 81:

In recent years researchers have recognized the limitations of the fragmentary measures....

Suggested: In recent years, researchers have recognized the limitations of the fragmentary measures...

3- Please, review the tables in page 12 and 13, the reference numbers are different from the numbers of the references written at the end of the manuscript.

4- Line 313/314: It might due to the mean difference (95% CI) was too close to the invalid line

suggested: It might be due to the mean difference (95% CI) was too close to the invalid line

5- Line 323: there is an extra space just before the word Herling, please omit this extra space.

Reviewer #3: Thank you for the opportunity to review the metanalysis entitled " Intravenous versus inhalational maintenance of anesthesia for quality of recovery in

adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis"

1) The premise of the analysis is interesting. However, there are concerning points that may/may not be fixable at this point. Important or possibly contentious question:

2) The included studies differ in the time of outcomes analysis - in the majority - smaller sized studies favored TIVA (are ambulatory/short outcome measure time) in addition represent inadequate work in this domain whereas other relatively larger studies showed “no effect”- plus studies are primarily female gender predominant together making it non-reproducible and more susceptible to selection bias. he problem with this analysis — in theory, you can select the trials you want to include and add them to come up with a number, but the question here is -would the average number apply to these diverse interventions which were compared with user-variable, by using different definitions of outcomes.

3) Introduction: Authors did not justify the rationale of the study. The logic "Wanders" and practically ends in the middle of a thought. Why do authors think that a metanalysis is necessary? Please explain the gaps of knowledge in introduction.

4) Very likely that your analysis is not powered to answer this question. I am sure you will agree that the standards for metanalysis should be higher in such questions due to possible impact on the varying clinical practice and choice of anesthetic agents. The ‘required information size’ necessary to account for heterogeneity and multiple comparisons when the RCTs are added, the necessary TSA boundaries are not reached. Moreover, power should be defined apriori.

5) Please add power analysis and sample size calculation.

6) After reading the conclusion, some may overinterpret the results--therefore avoid making any strong statements and include—"future research is likely to have an important impact."

7) Authors stated the conclusions “strongly” when in fact nothing can be concluded so far for sure. They do have a signal but the results remain inconclusive; considering limitations as discussed above in point 1 and 2. At most the authors should state the “results are inconclusive due to limited power”

8) It would be helpful if you show the results of sensitivity analysis. Please clarify what are duplicate studies?

9) Please include the time period of your search, your last search date, and last metanalysis done.

10) Please name the random effect model used or cite the exact model.

11) Non-cardiac surgeries in title may be a bit misleading. Non-cardiac surgeries can vary a lot with all respect. Authors should consider mentioning something like “Same-day surgeries”

12) Discussion: Similar to introduction. Too wordy and not focused to results. I would suggest reframing it according to the obtained results and just reporting the facts focused on the analysis. Plus, various confusing sentence wording and run-on sentences exist that should be restructured throughout. Awkward phrasing throughout the manuscript detracts from the overall quality of the manuscript. Limitation section should be a thoughtful list that caution your results.

Reviewer #4: The manuscript was good and can be accepted

Introduction was good written

Materials and Methods were good written

Results were clear

Discussion was good written

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: No

Reviewer #4: Yes: Mustafa Abd El Raouf

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2021 Jul 16;16(7):e0254271. doi: 10.1371/journal.pone.0254271.r004

Author response to Decision Letter 1


27 May 2021

Reviewer #2: Comments:

1- Line 69 and 70:

Requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide fast and high quality of recovery.

Suggested (kindly, observe that there are 2 suggested changes in the statement)

The requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide a fast and high quality of recovery.

We revised it in the manuscript.

2- Page 4 line 80 and 81:

In recent years researchers have recognized the limitations of the fragmentary measures....

Suggested: In recent years, researchers have recognized the limitations of the fragmentary measures...

We revised it in the manuscript.

3- Please, review the tables in page 12 and 13, the reference numbers are different from the numbers of the references written at the end of the manuscript.

We revised it in the manuscript.

4- Line 313/314: It might due to the mean difference (95% CI) was too close to the invalid line

suggested: It might be due to the mean difference (95% CI) was too close to the invalid line

We revised it in the manuscript.

5- Line 323: there is an extra space just before the word Herling, please omit this extra space.

We revised it in the manuscript.

Reviewer #3: Thank you for the opportunity to review the metanalysis entitled " Intravenous versus inhalational maintenance of anesthesia for quality of recovery in

adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis"

1) The premise of the analysis is interesting. However, there are concerning points that may/may not be fixable at this point. Important or possibly contentious question:

2) The included studies differ in the time of outcomes analysis - in the majority - smaller sized studies favored TIVA (are ambulatory/short outcome measure time) in addition represent inadequate work in this domain whereas other relatively larger studies showed “no effect”- plus studies are primarily female gender predominant together making it non-reproducible and more susceptible to selection bias. he problem with this analysis — in theory, you can select the trials you want to include and add them to come up with a number, but the question here is -would the average number apply to these diverse interventions which were compared with user-variable, by using different definitions of outcomes.

We agree with these limitations. We conducted the present meta-analysis also due to these controversies. And we just combined data with similar time point.

3) Introduction: Authors did not justify the rationale of the study. The logic "Wanders" and practically ends in the middle of a thought. Why do authors think that a metanalysis is necessary? Please explain the gaps of knowledge in introduction.

We revised it in the last paragraph in introduction.

4) Very likely that your analysis is not powered to answer this question. I am sure you will agree that the standards for metanalysis should be higher in such questions due to possible impact on the varying clinical practice and choice of anesthetic agents. The ‘required information size’ necessary to account for heterogeneity and multiple comparisons when the RCTs are added, the necessary TSA boundaries are not reached. Moreover, power should be defined apriori.

There seems no requirement for revision in this comment.

5) Please add power analysis and sample size calculation.

The estimated required information size (RIS) in TSA results was sample size calculation.

6) After reading the conclusion, some may overinterpret the results--therefore avoid making any strong statements and include—"future research is likely to have an important impact."

We revised it in the manuscript.

7) Authors stated the conclusions “strongly” when in fact nothing can be concluded so far for sure. They do have a signal but the results remain inconclusive; considering limitations as discussed above in point 1 and 2. At most the authors should state the “results are inconclusive due to limited power”

We revised it in the manuscript.

8) It would be helpful if you show the results of sensitivity analysis. Please clarify what are duplicate studies?

We showed the summarized results and alterations of sensitivity analysis. In the sensitivity analysis, we alternated meta-analytic effects model and excluded each study sequentially in score of each dimension. The results included too much single figures, so we did not upload these figures. If there is a need, we can submit the figures for supplementary files.

9) Please include the time period of your search, your last search date, and last metanalysis done.

It showed in the “Search Strategy and Study Selection” part.

10) Please name the random effect model used or cite the exact model.

We revised it in the manuscript.

11) Non-cardiac surgeries in title may be a bit misleading. Non-cardiac surgeries can vary a lot with all respect. Authors should consider mentioning something like “Same-day surgeries”

We had considered the problem, but not all studies included in our meta-analysis were ‘same-day surgeries’. When we registered the meta-analysis, we did plan to perform a meta-analysis about non-cardiac surgeries.

12) Discussion: Similar to introduction. Too wordy and not focused to results. I would suggest reframing it according to the obtained results and just reporting the facts focused on the analysis. Plus, various confusing sentence wording and run-on sentences exist that should be restructured throughout. Awkward phrasing throughout the manuscript detracts from the overall quality of the manuscript. Limitation section should be a thoughtful list that caution your results.

We revised it in the manuscript.

Attachment

Submitted filename: Response to Reviewers2.docx

Decision Letter 2

Martina Crivellari

9 Jun 2021

PONE-D-20-35422R2

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis

PLOS ONE

Dear Dr. Wu,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

ACADEMIC EDITOR:  Thank you for your submission. There are some minor questions for you. In the last revision you haven't addressed all the modifications requested. Please provide to make the paper suitable for publication. 

Please submit your revised manuscript by June 23rd. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Martina Crivellari

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #4: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #4: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #4: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #4: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #4: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: This comment is repeated (written and sent to the author before), as there were 2 modifications included but the author did one only, so please, do the second modifications.

- Line 69 and 70:

Requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide fast and high quality of recovery.

Suggested (kindly, observe that there are 2 suggested changes in the statement)

The requirement for effectiveness and efficiency of healthcare resources prompts anesthesiologists to consider techniques that provide a fast and high quality of recovery.

We revised it in the manuscript.

Originally in the last revision, I put the same comment, however you responded to one change only which is the addition of (The) to the start of the statement. There was another change which is the addition of (a) before (fast and high quality of recovery.).

Reviewer #4: The manuscript was s good

Introduction was good written and including the aim of the study

Materials and Methods were good written

Results were good written and illustrated

Discussion was good written

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Reviewer #2: No

Reviewer #4: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Decision Letter 3

Martina Crivellari

24 Jun 2021

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis

PONE-D-20-35422R3

Dear Dr. Wu,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Martina Crivellari

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Acceptance letter

Martina Crivellari

29 Jun 2021

PONE-D-20-35422R3

Intravenous versus inhalational maintenance of anesthesia for quality of recovery in adult patients undergoing non-cardiac surgery: a systematic review with meta-analysis and trial sequential analysis

Dear Dr. Wu:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Martina Crivellari

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Checklist. PRISMA 2009 checklist.

    (DOC)

    S1 File. Search strategy.

    (DOCX)

    S2 File. SoF table JCA.

    (DOCX)

    S3 File. Funnel plot.

    (DOCX)

    Attachment

    Submitted filename: Response to Reviewers.docx

    Attachment

    Submitted filename: Response to Reviewers2.docx

    Attachment

    Submitted filename: response to reviewer3.docx

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting Information files.


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