Association of Dynamometer-based Handgrip Strength with Postoperative Oxygen Requirement in Patients Undergoing General Anesthesia

Abstract

Introduction:

Postoperative patients who have received general anesthesia are administered oxygen therapy to prevent potential hypoxemia. Handgrip strength can be a supplemental indicator of postoperative residual muscle weakness and hence postoperative oxygen supplementation requirements.

Aims:

In this study, we measured voluntary muscle control using a dynamometer to detect hypoventilation due to residual neuromuscular blockade and its implication on postoperative oxygen requirements.

Methodology:

A prospective observational study where 50 patients were recruited. The recovery of handgrip strength, respiratory rate (RR), and SpO₂ was assessed postgeneral anesthesia at regular intervals till 6 h or till complete recovery, whichever was earliest. The duration of oxygen supplementation needed postoperatively was also noted.

Results:

We found that there was an increased RR immediately following surgery (P < 0.001), with a gradual return to baseline values within 120 min (P = 0.022), increased handgrip strength, starting at 30 min (P < 0.001), with return to the preoperative value by 120 min (P = 0.095). A drop in SpO₂ was noted right after surgery (P < 0.001), with a gradual return to baseline levels by 120 min.

Conclusions:

Handgrip strength was negatively correlated with SpO₂ and RR, particularly in the first 120 min postoperatively, implying that weaker handgrip strength corresponds to lower oxygen levels and higher RRs and hence is a good indicator of lung function. This indicates that oxygen supplementation must be continued for at least 120 min postextubation to prevent hypoventilation.

INTRODUCTION

Postoperative patients who have received general anesthesia are administered oxygen therapy to prevent potential hypoxemia. Research has advanced in determining the optimal postoperative oxygen levels, considering factors such as wound healing,[1] tissue oxygenation,[2,3,4] and lung atelectasis.[5] The need for supplemental oxygen varies based on factors such as impaired airway patency, ventilation–perfusion mismatch, and alveolar hypoventilation, which may result from residual neuromuscular blockade, surgical pain, and hemodynamic instability.[6]

However, pulse oximetry may not reliably detect hypoventilation when supplemental oxygen is administered. Additional monitoring methods, like arterial blood gas analysis, are necessary for effective hypoventilation detection.[7]

Residual neuromuscular blockade, affecting 10%–40% of patients postoperatively, can impair muscle strength and compromise airway protection.[8] Clinical assessments, including tests such as grip strength, tongue protrusion, and sustained head lift, are used to gauge recovery. Of these maneuvers, the standard to assess generalized motor strength, including the tone of the pharyngeal muscles, is the 5-s sustained head lift. Objective assessment includes handgrip strength dynamometer, train of four (TOF), and tetanic stimulation.[9]

A TOF ratio above 0.9 is considered sufficient for proper airway protection.[9] Nevertheless, postoperative respiratory dysfunction is possible even after the TOF ratio has returned to one.[10] Pei et al.[11] determined that handgrip strength can serve as a supplemental indicator of postoperative residual muscle weakness comparable to TOF. Krishna Prasad et al.[12] have proven that handgrip strength is more reliable than the TOF count in detecting residual muscle weakness. Even without overt signs like stridor, partial neuromuscular block can still cause respiratory complications, highlighting the need for extended oxygen supplementation.[13] In this study, we aimed to measure voluntary muscle control using a dynamometer to detect hypoventilation due to residual neuromuscular blockade and its implication on postoperative oxygen requirements.

Aim and objectives

Aim

The aim of this study was to find an association between dynamometer-based handgrip strength and postoperative oxygen requirements.

Objectives

• To assess the correlation between handgrip strength and SpO₂ levels

• To assess the duration of the postoperative oxygen requirement with handgrip strength technique between head-and-neck surgeries and nondominant upper limb surgeries.

METHODOLOGY

Study design

A hospital-based prospective observational study in patients undergoing elective surgeries under general anesthesia.

Study participants

The study was carried out in patients classified as the American Society of Anesthesiologists (ASA) Class 1 and 2, aged between 18 and 60 years, undergoing elective surgeries under general anesthesia.

Inclusion criteria

• ASA-1 and 2 category patients

• Adults aged 18–60 years of both genders

• Elective surgeries of the nondominant upper limb, head, and neck under general anesthesia

• Surgical duration of <3 h.

Exclusion criteria

• ASA-3 and above category patients

• Patient refusal to participate in the study

• Those with preexisting neuromuscular disease

• Obese patients with a body mass index ≤30 kg/m²

• Patients with a history of chronic pulmonary diseases

• Patients with cardiac and hepatorenal diseases

• Pregnant patients.

Sample size[12]

n = 2(Zα+Zβ)²/C²+3

• Zα =1.96 at 75% confidence interval

• Zβ =1.281 at 90% power

• C = 0.5 log (1 + r/1 − r)

• r = 0.86 (correlation coefficient)

• N = 44 cases (sample size)

• Total sample size = 44.

Outcome variables

Primary

• Handgrip strength in kilograms

• Peripheral saturation of oxygen (SpO₂).

Secondary

• Respiratory rate (RR)

• Duration of oxygen supplementation in hours.

METHODS

The study was initiated following approval from the institutional scientific and ethics committee [Annexure I]. It included patients classified as ASA Class 1 and 2, aged between 18 and 60 years, undergoing elective surgeries under general anesthesia.

The study protocol was thoroughly explained to all participants. A comprehensive preanesthetic evaluation and necessary investigations were conducted per the established protocol before the procedure. Written informed consent [Annexures II and III] was obtained during the preanesthetic assessment. In addition, the study participants were provided with a demonstration of the proper use of the dynamometer for handgrip measurement.

Handgrip strength was measured preoperatively by making the patients exert maximum grip a total of three times, with 1-min intervals between each attempt. The highest value obtained from the three measurements was recorded.

The patient’s nil per oral status was confirmed. The patients were shifted to the operating room 15 min before the procedure and positioned supine on the operating table.

Standard monitoring equipment, including a pulse oximeter probe, electrocardiogram, and noninvasive blood pressure cuff, was applied, and baseline vital signs, such as RR, oxygen saturation, heart rate, and blood pressure, were recorded using a multiparameter monitor.

A standard anesthesia protocol was followed for all patients. The patients were preloaded with Ringer’s lactate solution (10 mL/kg). Preoxygenation was performed using 10 L/min and 100% oxygen for 3 min. Subsequently, the patients were premedicated with intravenous doses of 0.02 mg/kg midazolam and 2 mcg/kg fentanyl. Patients were induced with 2 mg/kg of intravenous propofol. Then, following the loss of verbal response, vecuronium 0.1 mg/kg was administered to achieve muscle relaxation. Then, tracheal intubation was performed after adequate preoxygenation.

Anesthetic depth was maintained using sevoflurane at a minimum alveolar concentration of 0.8–1.2, combined with a 50:50 mixture of nitrous oxide and oxygen and additional doses of vecuronium. During the procedure, all the vitals were continuously monitored.

Approximately half an hour before the awaited end of the surgery, the patients received 15 mg/kg of paracetamol for analgesia and 0.15 mg/kg of ondansetron (up to a maximum of 4 mg) for antiemetic prophylaxis. After the procedure, neuromuscular blockade was reversed with neostigmine (0.05 mg/kg) and glycopyrrolate (0.01 mg/kg).

Tracheal extubation was performed once the patients were fully awake and responsive. Postoperatively, patients were administered oxygen supplementation at 5 L/min through a Hudson mask, and continuous monitoring of SpO₂ was conducted to ensure adequate oxygenation throughout the recovery period.

Postoperative pain was managed with 1 mg/kg of diclofenac sodium Intravenously (I.V).

Parameters assessed

Preoperative baseline measurements of SpO₂, RR, and handgrip strength (in kilograms) were systematically recorded for each patient.

Postextubation, simultaneous assessments of handgrip strength, SpO2, and RR were conducted at 30-min intervals for the first 4 h and subsequently at hourly intervals until 6 h postoperatively.

SpO₂ and RR were measured after the removal of the Hudson mask, with a 3-min monitoring period. Oxygen supplementation was terminated earlier if the SpO₂ remained above 94% on room air. The duration of supplemental oxygen therapy was also recorded for each patient.

All the data were collected using a prestructured pro forma [Annexure IV].

Statistical analysis

Data were sourced into Microsoft Excel 2013, (Albuquerque, New Mexico, United States). Statistical analysis was carried out using SPSS version 23.0 (SPSS Inc., IBM Business Analytics Software, Armonk, NY, USA) and The jamovi project (2025). jamovi (Version 2.6) [Computer Software]. Sydney, Australia. Karl Pearson’s correlation coefficient analysis was performed to ascertain the correlation between the variables.

Quantitative data were presented as mean (standard deviation) based on normality. A comparison was performed using repeated measures analysis of variance (ANOVA), followed by the Bonferroni test.

P < 0.05 was considered statistically significant.

RESULTS

Patient enrollment

We included patients aged 18–60 years with body mass index (BMI) under 30 kg/m² falling under ASA Class 1 and 2 undergoing elective surgeries (ear or upper limb) under general anesthesia and enrolled for the study.

Demographic characteristics

Basic demographic characteristics such as age, gender, and BMI are shown in Table 1.

Table 1.

Demographic data

Parameter	Value (mean±SD)
Age (years)	25.9±6.8
Gender (male/female)	28/22
BMI (kg/m2)	22.6±5.6

BMI=Body mass index, SD=Standard deviation

We studied 50 patients who fulfilled our study criteria. The mean age of our study population is 25.9 years, and the male-to-female ratio is 28:22. The mean BMI of our study is 22.6 kg/m².

Primary outcome

Handgrip strength recovered linearly with time, a trend similar to that of peripheral SpO2, as depicted in Table 2.

Table 2.

Comparison of handgrip strength

Time	Handgrip strength (kg) (mean±SD)	Percentage of baseline
Preoperative baseline	28.86±7.94	100.00
30 min	14.6±4.72	50.59
60 min	20.5±5.85	71.03
90 min	24.36±6.25	84.41
120 min	28.56±7.72	98.96

SD=Standard deviation

The Pearson’s correlation test showed a strong positive association between muscle strength measured with a handheld dynamometer and SpO₂, yielding a correlation coefficient of 0.99.

Secondary outcome

The RR recovered linearly with time, a trend corresponding to the peripheral SpO2, as depicted in Table 3.

Table 3.

Comparison of respiratory rate

Time	RR per min (mean±SD)	Percentage of baseline
Preoperative baseline	15.38±1.59	100
30 min	23.94±1.78	155.66
60 min	21.88±1.62	142.26
90 min	18.68±1.71	121.46
120 min	15.64±1.60	101.69

SD=Standard deviation, RR=Respiratory rate

The Pearson’s correlation test indicated a strong positive association between muscle strength measured with a handheld dynamometer and RR, with a correlation coefficient of 0.98.

All the patients required two hours of oxygen supplementation. After discontinuation of oxygen supplementation, no episodes of hypoxia were noted.

As shown in Table 4, handgrip strength increases gradually over time, starting from a low point at 30 min and progressively getting closer to the preoperative value by 120 min.

Table 4.

Handgrip strength at various time points

Parameter	n	Mean±SD	Repeated measures ANOVA (P)
Handgrip strength
Preoperative baseline	50	28.86±7.94	0.000 (highly significant)
30 min	50	14.60±4.72
60 min	50	20.50±5.85
90 min	50	24.36±6.25
120 min	50	28.56±7.72

SD=Standard deviation

The 30-min time point shows a lower mean (14.60) with a relatively small standard deviation (4.72), which suggests a significant decrease in handgrip strength in the immediate postoperative time.

The 120-min data (mean = 28.56) is very close to the preoperative baseline (28.86), indicating rapid recovery.

As shown in Table 5, the most significant changes in handgrip strength occur within the first 30–90 min postoperatively, with each pairwise comparison showing a significant improvement.

Table 5.

Post hoc analysis of handgrip strength at various time points (Bonferroni, P values)

Parameter (min)	Change, mean±SD	Bonferroni (P)
Handgrip strength
Preoperative - 30	14.260±5.631	0.000 (highly significant)
Preoperative - 60	8.360±4.434	0.000 (highly significant)
Preoperative - 90	4.500±2.887	0.000 (highly significant)
Preoperative - 120	0.300±0.909	0.095 (not significant)
30–60	−5.900±3.079	0.000 (highly significant)
30–90	−9.760±4.099	0.000 (highly significant)
30–120	−13.960±5.229	0.000 (highly significant)
60–90	−3.860±2.871	0.000 (highly significant)
60–120	−8.060±3.914	0.000 (highly significant)
90–120	−4.200±2.603	0.000 (highly significant)

SD=Standard deviation

Between 30 and 120 min, there is a consistent increase in handgrip strength, and each pairwise comparison is statistically significant.

The recovery was almost completed by 120 min, as shown by the nonsignificant difference between preoperative and 120 min (P = 0.095).

Since all the pairwise comparisons are highly significant, no major outliers exist.

The Bonferroni P values are adjusted for multiple comparisons, and it is clear that almost all of the changes between time points are highly significant (P < 0.001). This further confirms that the observed differences in handgrip strength are not likely due to chance.

As shown in Table 6, the RR was significantly higher 30 min postoperatively compared to the preoperative baseline, and it gradually decreased over time, returning closer to baseline by 120 min.

Table 6.

Respiratory rate at various time points

Parameter	n	Mean±SD	Repeated measures ANOVA (P)
RR
Preoperative baseline	50	15.38±1.59	0.000 (highly significant)
30 min	50	23.94±1.78
60 min	50	21.88±1.62
90 min	50	18.68±1.71
120 min	50	15.64±1.60

SD=Standard deviation, RR=Respiratory rate

The highly significant P value (P = 0.000) indicates that the observed changes in RR across these time points are statistically significant and not due to random variation.

Overall, these data demonstrate a clear trend of increasing RR immediately following surgery, with a gradual return to baseline values within 2 h.

As shown in Table 7, preoperative baseline to 30, 60, and 90 min shows highly significant decreases in RR (P < 0.001), meaning that there was a clear and marked increase in RR right after the procedure.

Table 7.

Post hoc analysis of the respiratory rate at various time points (Bonferroni, P values)

Parameter (min)	Change, mean±SD	Bonferroni (P)
RR
Preoperative - 30	−8.560±1.950	0.000 (highly significant)
Preoperative - 60	−6.500±1.581	0.000 (highly significant)
Preoperative - 90	−3.300±1.693	0.000 (highly significant)
Preoperative - 120	−0.260±0.633	0.022 (significant)
30–60	2.060±1.096	0.000 (highly significant)
30–90	5.260±1.893	0.000 (highly significant)
30–120	8.300±1.821	0.000 (highly significant)
60–90	3.200±1.761	0.000 (highly significant)
60–120	6.240±1.451	0.000 (highly significant)
90–120	3.040±1.641	0.000 (highly significant)

SD=Standard deviation, RR=Respiratory rate

The preoperative baseline to 120 min is significant (P = 0.022) but less dramatic than the earlier time points. This indicates that by 120 min, the RR has stabilized closer to the preoperative value, but the difference is still statistically significant.

Comparing 30–60 min, 30–90 min, and 30–120 min, all show highly significant increases in RR (P < 0.001). This suggests that after 30 min postoperatively, the RR consistently decreases in the subsequent time points.

The rate gradually returns toward the preoperative baseline level after 30 min, but some significant differences are still observed at later time points.

The Bonferroni correction verifies that the multiple comparisons are accounted for, ensuring the findings are robust and not due to chance.

As shown in Table 8, a statistically significant drop in SpO₂ is noted right after the surgery (30 min postoperatively), with the lowest point observed then.

Table 8.

Saturation of oxygen at various time points

Parameter	n	Mean±SD	Repeated measures ANOVA (P)
SpO2
Preoperative baseline	50	99.62±0.67	0.000 (highly significant)
30 min	50	96.04±1.64
60 min	50	97.38±1.43
90 min	50	98.56±1.20
120 min	50	99.58±0.73

SD=Standard deviation, SpO2=Saturation of oxygen

Gradual recovery in oxygen saturation at 60, 90, and 120 min, ultimately returning to baseline levels.

As shown in Table 9, the Bonferroni post hoc analysis reveals that changes in SpO₂ between several time points (preoperative baseline to 30, 60.90 min, and between 30, 60, 90, and 120 min) are all statistically significant (P < 0.001). These significant differences indicate notable shifts in SpO₂ levels at each of the time points.

Table 9.

Post hoc analysis of SpO₂ at various time points (Bonferroni, P values)

Parameter (min)	Change, mean±SD	Bonferroni (P)
SpO2
Preoperative - 30	3.580±1.739	0.000 (highly significant)
Preoperative - 60	2.240±1.559	0.000 (highly significant)
Preoperative - 90	1.060±1.202	0.000 (highly significant)
Preoperative - 120	0.040±0.283	1.000 (not significant)
30–60	−1.340±1.319	0.000 (highly significant)
30–90	−2.520±1.644	0.000 (highly significant)
30–120	−3.540±1.729	0.000 (highly significant)
60–90	−1.180±1.224	0.000 (highly significant)
60–120	−2.200±1.578	0.000 (highly significant)
90–120	−1.020±1.169	0.000 (highly significant)

SD=Standard deviation, SpO₂=Saturation of oxygen

The change between the preoperative baseline and 120 min showed a minimal mean difference (0.040) with P = 1, suggesting no significant difference in SpO₂ between these time points. This implies that SpO₂ levels have stabilized by 120 min after surgery to preoperative levels.

Overall, the findings highlight critical changes in oxygen saturation after surgery and the need for continuous monitoring in the early postoperative period to manage hypoxemia effectively.

DISCUSSION

In our study, handgrip strength showed a clear pattern following extubation. Handgrip strength remained at 50% of baseline at 30 min, 70% of baseline at 60 min, and almost reached (99%) baseline at 120 min after extubation.

None of the patients had a return to baseline muscle strength until 60 min.

Recovery in handgrip strength happens quickly, with significant improvement, especially after the 30-min postoperative time interval. By 120 min, handgrip strength had primarily returned to baseline levels.

The trend observed in our study corresponds with the findings of the study done by Krishna Prasad et al.,[12] who reported handgrip strength recovery to 50%, 75%, and 100% of baseline at 15, 45, and 210 min, respectively. The differences in time to fully recover can be explained by the use of a different muscle relaxant (namely, atracurium) and higher usage of opioids (fentanyl) throughout the procedure in their study.

Handgrip strength is consistently negatively correlated with SpO₂, particularly in the first 120 min postoperatively, implying that weaker handgrip strength corresponds to lower oxygen levels.

This relationship corresponds to the findings in the study done by Mgbemena et al.,[14] which showed a significant relationship between handgrip strength and lung function indices.

The RR in our study remained significantly elevated compared to baseline, with a 55% increase at 30 min, a 40% increase at 60 min, and a return to within 2% of baseline by 120 min postextubation. None of the patients in our cohort experienced respiratory complications leading to hypoxia.

These findings align with those of Krishna Prasad et al.,[12] who investigated postexpiratory flow rates and observed similar recovery patterns. The postexpiratory flow rate recovers to 50%–60%, 75%, and 100% of baseline at 15, 60, and 180 min postextubation, respectively. While their study focused on postexpiratory flow rate, both studies suggest a gradual recovery in respiratory parameters following extubation.

Our study demonstrated a negative correlation between RR and SpO₂, indicating that lower oxygen saturation levels were associated with higher RRs.

Our study has a few limitations:

1. Although it was suggested that partial pressure of oxygen be used through arterial blood gas sampling, this was not done in our study. Further study can be done to correlate the same.

2. The study was done in a single region. Hence, further diversity in the sample size can be added with other study centers added.

CONCLUSIONS

From the results, we conclude that handgrip strength is a good indicator of lung function. As we observed, muscle strength remained below baseline levels for a significant duration of 120 min following surgery. However, there were no signs of muscle weakness or respiratory distress. This indicates that oxygen supplementation must be continued for at least 120 min postextubation to prevent hypoventilation.

Informed consent statement

Informed consent was taken by the investigator after explaining the purpose of the study. The freedom to withdraw from the study at any time during the study was also explained prior to taking the informed consent.

Data availability statement

The data that support the study are available on request from the corresponding author of the study (can be contacted through email).

Ethical consideration

This study was initiated after getting accepted by the institutional scientific and ethics committee board (Protocol number: IECKMCMLR-03/2023/88) and registering in the Clinical Trials Registry (CTRI/2023/12/060490). The study was done in accordance with the Helsinki Declaration.

Conflicts of interest

There are no conflicts of interest.

Annexures

ANNEXURE I: INSTITUTIONAL ETHICS CERTIFICATE

ANNEXURE II

Patient Information Sheet

Sl.No –

Date:

Study title: Association of dynamometer based hand grip strength with postoperative oxygen requirement in patients undergoing general anaesthesia

Protocol number:

Principal Investigator: Dr AKSHAY A. KAMATH

Designation: Postgraduate student, Department of Anaesthesiology

Institution: Kasturba Medical College, Mangalore

Contact number: 8105763251

Guide: Dr. SHAILA S KAMATH

Designation: Professor, Department of Anaesthesiology

Institution: Kasturba Medical College, Mangalore

Co-guide: Dr. RASHMI R. AITHAL

Designation: Assistant Professor, Department of Anaesthesiology

Institution: Kasturba Medical College, Mangalore

Please read this form carefully. If you don't understand the language or any information in this document, please discuss it with your study doctor. If you decide to volunteer to take part in this study, you must sign the consent letter later.

Purpose of the study: To find an association between dynamometer-based handgrip strength and postoperative oxygen requirements

Information about the study: It will be an Observational Study involving 44 participants undergoing surgeries of the non-dominant hand, head and neck under general anaesthesia.

Your role in the study: To consent to accessing your medical records for research purposes.

What are the risks: This study does not present any risks for the participants. The Institutional Ethics Committee (IEC) of Kasturba Medical College, Mangalore, has approved this study.

Benefits: It will give us an idea about the effectiveness of a dynamometer in predicting postoperative oxygen requirements.

Cost of participating in the study: No cost factor is involved in participating.

Confidentiality of information: Personal data will be confidential and protected. Records maintained will be only for research purposes. A study number will be assigned to all participants.

Sharing of the research findings: The research findings will be shared in a timely fashion, but that confidential information will remain confidential. The research findings will be shared broadly through publications and research.

Voluntary participation: Entering a research study is voluntary. If you volunteer for a research study, you have the right to stop at any time, and you need not give any reason for doing so. The information, if obtained from, will remain confidential, irrespective of the same. The facilities that have been provided in the hospital will remain unchanged.

Whom to contact in case of any questions: If you have any questions and need further information about the study, you can contact:

Name: Dr. AKSHAY A. KAMATH

Designation: Postgraduate student of the Department of Anaesthesiology

Address: Kasturba Medical College, Mangalore.

Contact no: 8105763251

Contact details of the ethics committee:

Dr.Shalini Shenoy

Member Secretary

KMC Institutional Ethics Committee

Light house hill road, MANGALORE 575001

Mail: Shalini.shenoy@manipal.edu

Dr.Varadaraj Shenoy,

Chairperson of Kasturba Medical College Institutional Ethics Committee,

Former Professor of Paediatrics,

Father Muller Medical College, Mangalore-575002

Mail: vskudpi@rediffmail.com

ANNEXURE III

Informed Consent

I have read and understood the information/it has been read over to me and explained to me in an understandable language about the research project: Association of dynamometer based hand grip strength with postoperative oxygen requirement in patients undergoing general anaesthesia. I have had the opportunity to ask questions about it, and the questions I have asked have been answered satisfactorily. I consent voluntarily to participate in this research.

Name of Participant__________________

Signature of Participant ___________________

Date ___________________________

If illiterate, a literate witness must sign (if possible, this person should be selected by the participant himself/herself and should have no connection to the research team). Illiterate participants should include their thumbprint as well.

I have witnessed the accurate reading of the consent form to the potential participant, and the individual has had the opportunity to ask questions that the Researcher has properly answered in my presence. I confirm that the individual has agreed to participate in the research and has given consent freely.

Name of witness_____________________          Thumbprint of participant

Signature of witness ______________________                                 

Date _______________________

ANNEXURE IV:

Pro Forma

Correlation of Dynamometer based handgrip strength with postoperative oxygen requirement in patients undergoing general anesthesia

Identifier Code:

Age:

Gender:

Address:

Date of surgery:

Provisional diagnosis:

Proposed surgery:

Preoperative Examination:

General Physical Examination:

Height:

Weight:

BMI:

Pallor:

Icterus:

Cyanosis:

Clubbing:

Lymphadenopathy:

Edema

Vitals:

HR:

BP:

RR:

SpO2:

Airway Examination:

Systemic Examination:

Respiratory System

Cardiovascular System

Central Nervous System

Per Abdomen:

ASA-PS:

Investigations:

Hemoglobin

Total count

Platelet count

Serum electrolytes (if indicated)

Blood urea (if indicated)

Serum Creatinine (if indicated)

Total protein (if indicated)

Serum albumin (if indicated)

PT/INR (if indicated)

ECG (if indicated)

2D-Echo (if indicated)

Parameters	SpO2	RR	Handgrip strength
Preoperative (baseline)
Postoperative 30 min
60 min
90 min
120 min
150 min
180 min
210 min
240 min

RR=Respiratory rate

Funding Statement

Nil.