Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
The objective of this systematic review is to assess the safety and benefits of deliberate hypotension for orthopaedic surgery, especially on mortality and total perioperative blood transfusion.
Background
Description of the condition
Orthopaedic surgery always involves the manipulation of bone marrow, muscle tissue, and some venous plexus. This means that the amount of bleeding is relatively large during orthopaedic surgery. According to a recent report, the mean perioperative red blood cell loss was 1164 ± 852 mL for total hip replacement, 1453 ± 761 mL for total knee replacement, and 960 ± 730 mL for spinal surgery (Theusinger 2014). Furthermore, a large proportion of patients undergoing orthopaedic surgery are elderly (Kadono 2010), and the risk of anaemia increases with age (Ania 1997). Both anaemia and the associated risk of blood transfusion can increase morbidity and mortality and lengthen hospital stay after orthopaedic surgery (Lasocki 2015).
Blood transfusion, in particular the transfusion of red blood cells, is primarily aimed at restoring the oxygen‐carrying capacity by raising the haemoglobin concentration, thus ensuring an adequate oxygen supply to the vital organs. Blood transfusions are common practice in orthopaedic surgery (Gombotz 2007). Data from the Australian Better Safer Transfusion (BeST) programme showed that the mean perioperative blood transfusion rate in patients undergoing elective orthopaedic surgery was 32% (Blood Matters Program 2011). However, allogeneic transfusions can bring about potential adverse clinical outcomes, such as transmission of micro‐organisms, haemolysis, allergies, nonhaemolytic febrile transfusion reactions, congestive heart failure or acute lung injury, increased mortality, lengthened hospital stay, and raised costs (Bernard 2009; Isbister 2011). In view of these adverse effects, and an increasing shortage of blood, many researchers propose alternatives to transfusion or blood conservation measures to minimize allogeneic red blood cell transfusion, such as preoperative autologous blood donation, acute normovolemic haemodilution, perioperative blood salvage, epoetin alfa to stimulate erythropoiesis, haemostatic agents, and some 'patient blood management' programmes (Dragan 2012; Erpicum 2012; Goodnough 2012; Keating 2002; Spahn 2013).
Due to complex vascularity, bleeding during orthopaedic surgery often manifests as diffused bleeding and is not readily controllable by conventional surgical techniques, especially when manipulation involves intrabony capillaries. Orthopaedic surgery is different from other types of surgeries which always have a definite bleeding site and can achieve good haemostasis by ligation or electrocautery. How to reduce blood loss, thus reducing allogeneic blood transfusion, is challenging in orthopaedic surgery.
Description of the intervention
Deliberate hypotension refers to any technique that decreases a person's blood pressure during surgery, to reduce bleeding and the need for allogeneic transfusion, and improves the surgical field. The objective of deliberate hypotension is usually defined as lowering the systolic blood pressure to values between 80 and 90 mmHg, or the mean arterial blood pressure to values between 50 and 65 mmHg in people without hypertension, or a 30% reduction of baseline mean arterial blood pressure in people with hypertension (Degoute 2007). Given the potential risks, deliberate hypotension is not generally used in people with a history of cardiac, cerebrovascular, renal, hepatic, or severe peripheral vascular disease (Aken 2000). Deliberate hypotension is also contraindicated in persons with uncorrected hypovolaemia and severe anaemia (Aken 2000; Degoute 2001).
Deliberate hypotension was first introduced by Gardner who used arteriotomy to reduce arterial blood pressure during surgery (Gardner 1946). Various techniques for inducing hypotension have been used since then, including controlling venous return (e.g. through positioning of the patient), pharmacological interventions such as volatile anaesthetics (Ankichetty 2011), intravenous anaesthetics (Kosucu 2014), vasodilator drugs (Barrett 2015), β‐adrenoceptor antagonists (Shams 2013), or intrathecal anaesthesia (Niemi 2000). These hypotensive agents can be used alone, or in combination, and ideally should "be easy to administer, have a short onset time, an effect that disappears quickly when administration is discontinued, a rapid elimination without toxic metabolites, negligible effects on vital organs, and a predictable and dose‐dependent effect" (Degoute 2007). Deliberate hypotension has been emphasized by an ever‐increasing number of anaesthesiologists and surgeons, especially for orthognathic surgery, neurosurgery, orthopaedic surgery, cardiovascular surgery, and liver surgery (Boonmak 2013; Dolman 2000; Paul 2007; Tagarakis 2014; Wang 2003).
How the intervention might work
The physiological basis of deliberate hypotension varies with the techniques used, some reduce the blood flow to the vessels within the surgical field by reducing cardiac output (e.g. esmolol); some control blood loss by reducing peripheral vascular resistance (e.g. inhalation anaesthetics and vasodilators); and others combine these two factors (e.g. epidural and anaesthesia and labetalol). However, each hypotensive technique has its own disadvantages. For example, the degree of hypotension for spinal anaesthesia is hard to predict and control due to the absence of a dose‐effect relationship (Covino 1989). Inhalation anaesthetics increase intracranial pressure (Massei 1994), nicardipine impairs cerebral autoregulation (Endoh 2000), peripheral vasodilators arouse reflex tachycardia (Fahmy 1989; Kimura 1999), and sodium nitroprusside can produce toxic metabolites (Tinker 1976). Clinically, a combination of these hypotensive techniques can reduce the concentration of each drug, and avoid their adverse effects (Degoute 2007).
The benefit of deliberate hypotension in blood conservation is mainly shown in three aspects: reducing blood loss, cutting down the need for allogeneic blood, and improving the quality of the surgical field. Several studies confirmed these benefits and found that the use of hypotensive anaesthesia could shorten the operation time, reduce the risk of tissue oedema caused by ligation or electrocautery, and improve myocardial performance by reducing cardiac preload and afterload (Dragan 2012; Tagarakis 2014; Wang 2003). A recent retrospective cohort study found that hypotensive anaesthesia had a potential ability to minimize postoperative length of hospital stay for patients undergoing orthognathic surgery (Ettinger 2015). In 2007, a meta‐analysis "provided some support for the use of deliberate hypotension" in orthopaedic surgery (Paul 2007).
Why it is important to do this review
Although deliberate hypotensive anaesthesia has been considered to be one of the blood conservation techniques for orthopaedic surgery (Dragan 2012), multiple complications accompany this technique. The adequacy of blood flow to the vital organs during the hypotensive period and the accompanying risks of deliberate hypotension, such as permanent cerebral damage, delayed awakening, and death have raised particular concerns for clinical practitioners (Choi 2008). For patients with known hypertension, elderly patients, and surgeries requiring special positions (e.g. beach‐chair position and reverse Trendelenburg position), it is doubtful whether mean arterial blood pressure with a value between 50 and 65 mmHg is sufficient for the vital organs, in particular the brain. It was reported that "the mortality rate associated with deliberate hypotension was about 0.22% to 0.34% in the 1950s, and nonfatal complications (mainly referred to cerebral, coronary, and renal circulations) occurred 908 times (about 2.61% to 3.25%)" (Little 1955). In the early 1960s, a report following 9107 hypotensive anaesthetics showed a mortality of 0.10% (Enderby 1961). No estimates have been published recently. This may be because with better hypotensive technique and stricter indications, the safety of the use of deliberate hypotension has been improved. Even so, the use of deliberate hypotension is not without risk, and no systematic review and meta‐analysis on the safety of this technique has been conducted until now. Whether deliberate hypotension will increase the risk of mortality and morbidity is still unknown. Still, the benefits of deliberate hypotension for orthopaedic surgery have not been updated since 2007. We will focus on the safety of deliberate hypotension and further test its utility in orthopaedic surgery in this current review.
Objectives
The objective of this systematic review is to assess the safety and benefits of deliberate hypotension for orthopaedic surgery, especially on mortality and total perioperative blood transfusion.
Methods
Criteria for considering studies for this review
Types of studies
We will include all parallel randomized controlled trials (RCTs) that compare the effect of using deliberate hypotension with not using deliberate hypotension for orthopaedic surgery on any primary and secondary outcomes.
We will include studies irrespective of language or publication status.
We will exclude observational studies, randomized cross‐over trials, prospective cohort studies and quasi‐randomized studies.
Types of participants
We will include all orthopaedic surgical participants irrespective of age, sex or anaesthetic methods used. We will also include spinal surgery performed by neurosurgeons if deliberate hypertension was used during surgery.
We will exclude participants with a history of neurologic or psychiatric dysfunction, uncontrolled hypertension, ischaemic heart disease, stroke, renal or hepatic dysfunction, severe peripheral vascular disease, uncorrected hypovolaemia, and anaemia (haemoglobin level ≤ 110 g/dL).
Types of interventions
The intervention group uses deliberate hypotension by any method. The pressure should be controlled within an acceptable limit, namely, lowering the systolic blood pressure to values between 80 and 90 mmHg, or the mean arterial blood pressure to values between 50 and 65 mmHg in people without hypertension, or a 30% reduction of baseline mean arterial blood pressure in people with hypertension. For the control group, blood pressure is not specifically controlled.
In today's clinical practice, the definition of blood conservation does not refer to only one method; it always combines several techniques. We will not exclude studies combining deliberate hypotension with any method of haemodilution (hypervolaemic or normovolemic) or cell salvage. We will not exclude studies involving other pharmacological interventions (use of haemostatic agents such as haemocoagulase, tranexamic acid, etc) to reduce blood loss if they were applied equally to groups.
Types of outcome measures
We will evaluate the difference between the intervention group and the control group on the following outcomes.
Primary outcomes
Overall mortality.
All causes: we will use the data available in each RCT within 28 days after surgery.
Secondary outcomes
Volume of blood transfused. We will record the total volume of perioperative (including the amount of blood returned to the patient from cell salvage) blood transfusion. The blood transfusion refers to the transfusion of red blood cells.
Intraoperative blood loss. We will measure the intraoperative blood loss by recording the volume of blood collected in the suction bottles and the increased weight of gauzes. Study authors' own definitions of these severe adverse events should be eligible clinically. We will use the data before hospital discharge in each RCT. If this is not available, we will use the data within 28 days after surgery.
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Occurrence of serious adverse events after surgery. We define serious adverse events as severe cerebral, cardiac, renal, hepatic, and haematologic complications.
We define severe cerebral complications as cerebral ischemias or cerebral stroke diagnosed or suspected by using study authors' own definition (disturbance of consciousness with Glasgow score lower than eight, computed tomography (CT), magnetic resonance imaging (MRI), etc).
We define severe cardiac complications as myocardial ischemias, myocardial infarction, pulmonary oedema, or heart failure diagnosed or suspected by using study authors' own definition (creatine kinase isoenzyme (CK‐MB) level, electrocardiographic changes, chest radiograph, etc).
We define severe renal complications as renal dysfunction or renal failure diagnosed or suspected by using study authors' own definition (serum creatinine level, urine output, etc).
We define severe hepatic complications as liver dysfunction or liver failure diagnosed or suspected by using study authors' own definition (serum transaminase level, etc).
We define severe haematologic complications as severe coagulation dysfunction and thromboembolism diagnosed or suspected by using study authors' own definition (coagulation tests, ultrasound, etc).
Length of hospital stay.
Search methods for identification of studies
Electronic searches
We will search the current issue of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), EMBASE (Ovid SP), CINAHL (via EBSCOhost), ISI Web of Science, ScienceDirect (via Elsvier), and four Chinese databases: CNKI (China National Knowledge Infrastructure), Wanfang, VIP (vip citation database), and SinoMed (updated version of China Biology Medicine disc) from 2000 to date. We will combine our subject search terms with the Cochrane highly sensitive strategies for identifying RCTs described in Section 6.4 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), to search MEDLINE. We will apply the MEDLINE search strategy provided in Appendix 1 to search other electronic databases.
We will not impose any language restriction.
Searching other resources
We will search the BIOSIS databases (http://www.biosis.org/), SIGLE database (opensigle.inist.fr), and HMIC database (www.ovid.com/site/catalog/DataBase/99.jsp?top=2&mid=3&bottom=7&subsection=10) for conference proceedings and grey literature. We will search www.clinicaltrials.gov and www.controlled‐trials.com/ to identify unpublished trials. For literature without full‐text, we will email the study author. We will also screen the reference lists of all eligible trials and reviews.
Data collection and analysis
Selection of studies
Two study authors (JJ and ZR) will import all search results into Endnote software, and remove duplicate records of the same trial. If uncertainties remain, we will contact the corresponding study author. We (JJ and ZR) will then independently screen the title and abstracts and remove any obviously irrelevant studies. After retrieving the full‐texts of any potentially relevant studies, we will carefully read them and determine their eligibility. We will resolve any disagreements between the two review authors by discussion with a third review author (YY) for the content area and a fourth review author (LB) for the methodological area. We will make a decision regarding the inclusion of the study after a consensus is reached. We will record the selection process in sufficient detail to complete a PRISMA flow diagram (Moher 2009), and a 'Characteristics of excluded studies' table (RevMan 2014). We will not impose any language restrictions.
Data extraction and management
Two review authors (JJ and ZR) will independently extract data (including methods, participants, interventions, outcomes, results, and other information) and enter them in our prespecified data collection form (see Appendix 2). First, we will give a study an identity (ID) by using the family name of the first study author and publication year (e.g. Smith 2000) and record the date, site, and the name of the person undertaking data collection. We will record whether informed consent and ethical approval were obtained. After checking the criteria for this study, we will confirm whether the study is included or give the brief reason for exclusion. For the included study, we will enter the following data.
Methods and potential sources of bias: study design characteristics and other information to assess the risk of bias. This will be further discussed in the following part.
Participants and setting: age, sex, American Society of Anesthesiologists (ASA) grade, type of surgery, type of anaesthesia, duration of surgery, comorbidity, transfusion trigger method.
Interventions: total number of intervention and control groups, method of deliberate hypotension, the controlled level of mean arterial blood pressure, length of deliberate hypotension, whether combined with haemodilution (hypervolaemic or normovolemic) or cell salvage, and the detailed method.
Outcomes: outcome definition (with diagnostic criteria and severity if available) and time points of prespecified outcomes (if relevant); unit of measurement (if relevant).
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Results: sample size; missing participants with a detailed description in the 'Risk of bias' assessment tool.
For continuous data, we will extract the mean, the standard deviation (SD), and sample size; for studies that only report the average or variation instead of SD, we will make some transformations as follows: if a standard error (SE) is given (of a mean calculated from within an intervention group), SD will be obtained from the SE by multiplying by the square root of the sample size; if a 90%, 95%, or 99% confidence interval (CI) is given, SD will be obtained by dividing the length of the CI by 3.29, 3.92, or 5.15 respectively (the value needs to be replaced specific to the t distribution if the sample size is less than 100 in each group), and then multiplying by the square root of the sample size; if a P value, either an exact value or a level of significance, is reported from t test, a relative t value can be obtained from a table of the t distribution, and then SE can be obtained by dividing the difference in means by the t value. Finally, SD will be obtained by dividing the SE by the square root of the sum of the reciprocal of the sample size in the intervention and control group; If median and interquartile range (IQR) are given for the symmetrical data, the median will be considered as similar as the mean and the IQR will be approximately 1.35 SD (Higgins 2011).
For the dichotomous variables, we will extract the number of events occurred and the sample size. For the studies only reporting odds ratio or risk ratio that are accompanied by measures of uncertainty, such as 95% CI or an exact P value, we will use formulae to transform them into SEs.
For the same outcome, if data are presented as continuous data in some studies and as dichotomous data in other studies, we will convert the SE of the log odds ratios to the standard error of a standardized mean difference (SMD) by multiplying "√3／π (0.5513)", or alternatively, convert SMDs to log odds ratios by multiplying by "π／√3 (1.814)" (Chinn 2000).
For rare events that may re‐occur to a person or several rare events concurring in one person during the study follow‐up period (Poisson data), we will extract the total number of events in each group and the total number of person‐time at risk in each group; rates relate the counts to the amount of time during which they could have happened (Higgins 2011; Chapter 9.2.5).
Since we set a fixed time‐point (28 days) to follow, we will analyse the time‐to‐event outcome (mortality) as dichotomous data.
Other information: the resource of the study, contact details, publication type, any funding sources and detailed information.
If the study has multiple intervention groups and creates several comparisons, then each comparison will use one data extraction form and the study ID will be followed by a comparison number (e.g. Smith 2000‐1). The location of the information above in the original report should be listed in the data extraction form. For the information that we are unable to extract from the available report, we will contact the original study authors. We will resolve any disagreements in data extraction by discussion between two review authors, and if necessary, with a third review author (YY).
After reaching consensus, we will enter the collected data into Review Manager 5 (RevMan 2014).
Assessment of risk of bias in included studies
Two review authors (JJ and KN) will independently assess the risk of bias for each eligible study by using the 'Risk of bias' assessment tool, which includes seven domains, i.e., sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective outcome reporting, and other bias. According to this two‐part tool, we first describe what was reported in the study and enter the relative information in the 'Risk of bias' table, we will then assign a judgement of 'low risk' of bias, 'high risk' of bias, or 'unclear risk' of bias. We will refer to Table 8.5.b of the Cochrane Handbook for Systematic Reviews of Interventions for judgement criteria (Higgins 2011). Finally, we will generate a 'Risk of bias' summary figure and a 'Risk of bias' graph figure using Review Manager 5 (RevMan 2014). We will resolve any disagreements on this assessment by discussion with a third review author (YY).
If we assign all seven domains to 'low risk' of bias, we will classify the study as 'low risk'; if we assign one or more domain(s) to 'unclear risk' of bias, we will classify the study 'unclear risk'; if we assign one or more domain(s) to 'high risk' of bias, we will classify the study as 'high risk'. If most information of an outcome is from studies at low risk of bias, then the result of this outcome will be at low risk of bias; if most information of an outcome is from studies at low or unclear risk of bias, then the risk of bias of the outcome will be unclear; if most information comes from studies at high risk of bias, then the result will be hard to interpret (Higgins 2011).
Measures of treatment effect
We will use the risk ratio (RR) and 95% CI for dichotomous data. For the studies only reporting odds ratio or risk ratio, we will use the generic inverse‐variance method if they are accompanied by SE, 95% CI or an exact P value. We will use the mean difference (MD) and 95% CI for continuous data when the outcomes in all included studies are made on the same scale. In the case of the same outcome with a variety of ways to measure, we will use SMD to combine the standardized results with a uniform scale.
For the rare events that may re‐occur to a person during the study follow‐up period, we will treat such counts as rate data and obtain the SE from the rate ratio to undertake analysis by using the generic inverse‐variance method. In addition, we will use trial sequential analysis (TSA) to calculate the required information size for the primary outcome and one of the secondary outcomes (occurrence of serious adverse events after surgery). The calculation will be based on the rate of our control group and the statistics with α and β error of 0.05 and 0.20 (two‐sided test) and RR reduction of 20%, then the calculated sample size will be multiplied by the heterogeneity in our result (Brok 2009; Pogue 1997; Wetterslev 2009).
We will turn to a knowledgeable statistician for help if necessary. We will consider P < 0.05 statistically significant.
Unit of analysis issues
Our review will only include parallel designed trials, so, a unit‐of‐analysis error from cluster‐randomized trials and cross‐over trials could be avoided.
For the studies with more than two intervention groups, such as experimental groups with different hypotensive levels, or with different methods to induce hypotension, or combined with other methods to modulate blood loss (e.g. haemodilution), or one experimental group with two control groups, we will split the ‘shared’ group with smaller sample size and create two or more comparisons. Although a unit‐of‐analysis error will occur accordingly, this will facilitate the investigation of heterogeneity and subgroup analyses.
Dealing with missing data
We will contact the study author of the original report for important missing statistics. If these data still cannot be obtained, we will just use the available data. If no usable data can be extracted from an eligible study, we will discuss the potential implications of the missing data instead of excluding the study from our review. For the participants missing due to drop‐out, if 'missing at random', we will perform analysis based on the available data, if not, we will at least do an available case analysis or if necessary, do an intention‐to‐treat (ITT) analysis. If a study does not mention withdrawals, we will assume that there were no drop‐outs.
Assessment of heterogeneity
We will consider heterogeneity (clinical and methodological) before performing pooled analysis. We will use a chi2 test with the I2 statistic (with statistical significance set at the level of two‐tailed 0.10) to describe the percentage of the total variance across studies from heterogeneity rather than from chance. We will consider the value of no less than 40% as having statistical heterogeneity, and if all data are correct after checking again, we will then explore potential clinical heterogeneity by conducting prespecified subgroup analysis (Higgins 2011).
Assessment of reporting biases
In order to avoid publication bias, we will try our best to obtain data from unpublished eligible trials. We will assess reporting biases by using funnel plots if the result of the primary outcome is from at least 10 trials (Egger 1997). We will not use any tests for funnel plot asymmetry but will qualitatively assess this bias by visual inspection.
Data synthesis
We will use Review Manager 5 software to perform the pooled analysis for the outcomes from more than one study (RevMan 2014). If I2 ＜ 40%, namely there is no statistical heterogeneity among studies, we will use a fixed‐effect model, otherwise, we will use a random‐effects model. In case of evidence of significant heterogeneity, we will compare the results of both fixed‐effect and random‐effects models to evaluate if the small study effect has an influence on the treatment effect estimate. If an outcome originated from the data of only one study, we will calculate the estimates of effect from this single study. For the results that could not be analysed via meta‐analysis, we will only perform a qualitative systematic review.
Subgroup analysis and investigation of heterogeneity
We will perform subgroup analyses in the presence of statistical heterogeneity (I2 ≥ 40%) or an indication of clinical heterogeneity (Higgins 2011); we will consider the following potential subgroups.
Age group: younger than 16 (children), 17 to 65 (adult), older than 65 years of age (elderly).
Mean arterial blood pressure controlled level (mean arterial blood pressure ≥ 60 mmHg; mean arterial blood pressure 55 to 60 mmHg; mean arterial blood pressure < 55mmHg); we will use meta‐regression to assess the relationship between level of arterial pressure and the primary outcome if no less than 10 studies are included in the review.
Type of orthopaedic surgery.
Sensitivity analysis
In order to determine the robustness of our meta‐analysis, we plan to conduct sensitivity analyses by sequentially removing each high risk study and reanalysing the remaining dataset for the primary outcomes (producing a new analysis for each study removed). Additionally, a previous study suggested that the probability of positive results reported in studies of certain languages, such as Chinese, were significantly higher than other languages (Vickers 1998). Therefore, we plan to perform a 'special' sensitivity analysis by excluding Chinese studies to confirm if the Chinese articles affect the results of pooled analysis.
'Summary of findings' table and GRADE
We will use the principles of the GRADE system to assess the quality of the body of evidence associated with the following outcomes (Guyatt 2008; Guyatt 2011).
Overall mortality.
Volume of blood transfused.
Intraoperative blood loss.
Occurrence of serious adverse events after surgery.
Length of hospital stay.
We will produce a 'Summary of findings' table using the GRADE software (GRADEproGDT 2015). The GRADE approach appraises the quality of a body of evidence based on the extent to which one can be confident that an estimate of effect or association reflects the item being assessed. The quality of a body of evidence takes into consideration within‐study risk of bias (methodologic quality), the directness of the evidence, heterogeneity of the data, precision of effect estimates, and risk of publication bias.
Acknowledgements
We thank Jane Cracknell (Managing Editor of the Cochrane Anaesthesia, Critical and Emergency Care Review Group (ACE)) for her guidance. We thank Professor TIansong Zhang for his suggestion on statistical methods used to measure the treatment effect. We also would like to thank Andrew Smith, (Senior editor), Jing Xie (content and statistical editor), James Paul, Meg Rosenblatt, Richard P Dutton (peer reviewers), and Clare Dooley (copyeditor) for their help and editorial advice during the preparation of this protocol for the systematic review.
Appendices
Appendix 1. MEDLINE (Ovid SP) search strategy
1. exp Hypotension, Controlled/ or exp Hemodilution/ or ((hypervolaemic or normovolemic) adj3 haemodilution).mp. or ((deliberate or induced or controlled or an?esthesia) and hypotens*).mp. 2. exp Orthopedic Procedures/ or exp Orthopedics/ or (ort?op?ed* adj5 (surg* or operat* or patient*)).mp. 3. ((randomized controlled trial or controlled clinical trial).pt. or randomized.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab.) not (animals not (humans and animals)).sh. 4. 1 and 2 and 3
Appendix 2. Data extraction form
| Data extraction form for CARG 327 | |||||||
| Study ID (family name of 1st author and year of publication and comparison number) | |||||||
| Date of data extraction | |||||||
| Site of data extraction | |||||||
| Name of person extracting data | |||||||
| Date of completing data extraction | |||||||
| Title | |||||||
| Contact details (Email address) | |||||||
| Source: electronic database/ unpublished information/ personal communications/other | |||||||
| Publication type | |||||||
| Informed consent obtained: Yes No Unclear | |||||||
| Ethical approval obtained: Yes No Unclear | |||||||
| Study funding sources | |||||||
| Possible conflicts of interest | |||||||
| Notes | |||||||
| Eligibility | |||||||
| Characteristics | Eligibility criteria | Location in text | |||||
| Yes | No | Unclear | |||||
| Type of study | The study was a randomized controlled trial without any significant ethical issues | ||||||
| Participants | The participants received an orthopaedic surgery? | ||||||
| The participants were free of any history of neurologic or psychiatric dysfunction, uncontrolled hypertension, ischaemic heart disease, stroke, renal or hepatic dysfunction, severe peripheral vascular disease, uncorrected hypovolaemia, or anaemia (haemoglobin level ≤ 110 g/dL) | |||||||
| Intervention | The experimental group use deliberate hypotension within an acceptable limit | ||||||
| The control group did not use deliberate hypotension | |||||||
| Types of outcome (Did the study report any one of) | Overall mortality | ||||||
| Volume of blood transfused | |||||||
| Intraoperative blood loss | |||||||
| Occurrence of serious adverse events after surgery | |||||||
| Length of hospital stay | |||||||
|
If any of the above answers are ‘No’, do not proceed and make a justification as: Included Excluded and should be listed in the excluded table Excluded and should NOT be listed in the excluded table More information needed before inclusion decision (contact the original author) Reason for exclusion: If included, continue | |||||||
| Population and setting | |||||||
| Intervention | Control |
P value (if any) |
Location in text | ||||
| Number of participants (n) | |||||||
| Number of drop‐outs and the reason (n) | |||||||
| Age (mean/SD) | |||||||
| Sex (M/F, n) | |||||||
| ASA grade (Ⅰ/Ⅱ/Ⅲ/Ⅳ, n) | |||||||
| Comorbidity | |||||||
| Inclusion criteria | |||||||
| Excluded criteria | |||||||
| Type of surgery | |||||||
| Type of anaesthesia | |||||||
| Transfusion trigger method | |||||||
| Notes | |||||||
| Risk of bias assessment | |||||||
| Domain | Risk of bias | Support for judgement | Location in text | ||||
| Low | High | Unclear | |||||
| Random sequence generation (selection bias) | |||||||
| Allocation concealment (selection bias) | |||||||
| Blinding of participants and personnel (performance bias) | |||||||
| Blinding of outcome assessment (detection bias) | |||||||
| Incomplete outcome data (attrition bias) | |||||||
| Selective outcome reporting? (reporting bias) | |||||||
| Other bias | |||||||
| Notes: | |||||||
| Intervention groups | |||||||
| Comparison | |||||||
| Description | Location in text | ||||||
| Intervention | Control | ||||||
| Total number | |||||||
| Method of deliberate hypotension | |||||||
| Mean arterial blood pressure level | |||||||
| Duration of deliberate hypotension | |||||||
| Whether combined with haemodilution or cell salvage and the detailed method | |||||||
| Notes: | |||||||
| Outcomes | |||||||
| Outcomes the study reported | |||||||
|
Outcome (number) (Repeat this section for each outcome) | |||||||
| Description | Location in text | ||||||
| Outcome name | |||||||
| Outcome definition | |||||||
| Timing of measurement | |||||||
| Statistics for measurement | |||||||
| Unit of measurement | |||||||
| Is outcome selectively reported? | |||||||
| Notes: | |||||||
|
Results (Repeat the relative section for each outcome at each time point) | |||||||
| Dichotomous outcome or rare events | |||||||
| Description | Location in text | ||||||
| Outcome | |||||||
| Time point | |||||||
| Results | Intervention | Control | |||||
| Number of events | Number of participants or number of person‐time at risk in each group | SE | Number of events | Number of participants or number of person‐time at risk in each group | SE | ||
| Number of drop‐outs and the reason | |||||||
| Notes (For the studies only report odds ratio or risk ratio that accompanied by 95% CI or an exact P value, the formulae used to transform them into SE): | |||||||
| Continuous outcome | |||||||
| Description | |||||||
| Outcome | |||||||
| Time point | |||||||
| Results | Intervention | Control | |||||
| Mean | SD (or other variance) | No. of participants | Mean | SD (or other variance) | No. of participants | ||
| Number of drop‐outs and the reason | |||||||
| Notes (For the studies that report the average or variance instead of SD, the formulae use to transform them into SD): | |||||||
What's new
| Date | Event | Description |
|---|---|---|
| 31 July 2017 | Amended | The published protocol protocol will be withdrawn |
Contributions of authors
Jia Jiang (JJ), Yun Yue (YY), Li Bo (LB), Ran Zhou (RZ)
Conceiving the review: JJ, RZ, LB, YY
Co‐ordinating the review: JJ
Undertaking manual searches: JJ, RZ
Screening search results: JJ, ZR, YY
Organizing retrieval of papers: JJ
Screening retrieved papers against inclusion criteria: JJ, RZ, LB, YY
Appraising quality of papers: JJ, ZR, LB
Abstracting data from papers: JJ, RZ
Writing to authors of papers for additional information: JJ, RZ
Providing additional data about papers: RZ
Obtaining and screening data on unpublished studies:JJ, RZ
Data management for the review: JJ,RZ
Entering data into Review Manager 5 (RevMan 2014): JJ, RZ
RevMan statistical data: JJ, RZ
Interpretation of data: JJ, RZ, YY
Statistical inferences: JJ, LB
Writing the review: JJ, RZ
Guarantor for the review (one author): JJ
Person responsible for reading and checking review before submission: RZ
Sources of support
Internal sources
No sources of support supplied
External sources
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Young Program of National Natural Science Funds of China, China.
Program Name: The Establishment of Evidence‐based Medical Record about Doctor‐patient Building through Integrated Therapy of Traditional Chinese and Western Medicine on Digestive System Diseases (Program Approval No.: 81303151)
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Beijing NOVA Programme, China.
(Number xxjh2015A093Number:Z1511000003150125)
Declarations of interest
Jia Jiang: none known.
Yun Yue: none known.
Li Bo: none known.
Ran Zhou: none known.
Notes
July 2017
After discussion with the authors, it has been decided to withdraw this published protocol as it is not consideed a priority topic.
Withdrawn from publication for reasons stated in the review
References
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