Joanna Sutherland

Forced air warming during sedation in the cardiac catheterisation laboratory: a randomised controlled trial

Objective Forced air warming (FAW) during general anaesthesia is a safe and effective intervention used to reduce hypothermia. The objective of this study was to determine if FAW reduces hypothermia when used for procedures performed with sedation in the cardiac catheterisation laboratory. Methods A parallel-group randomised controlled trial was conducted. Adults receiving sedation in a cardiac catheterisation laboratory at two sites were randomised to receive FAW or usual care, which involved passive warming with heated cotton blankets. Hypothermia, defined as a temperature less than 36°C measured with a sublingual digital thermometer after procedures, was the primary outcome. Other outcomes were postprocedure temperature, shivering, thermal comfort and major complications. Results A total of 140 participants were randomised. Fewer participants who received FAW were hypothermic (39/70, 56% vs 48/69, 70%, difference 14%; adjusted RR 0.75, 95% CI=0.60 to 0.94), and body temperature was 0.3°C higher (95% CI=0.1 to 0.5, p=0.004). FAW increased thermal comfort (63/70, 90% vs51/69, 74% difference 16%, RR 1.21, 95% CI=1.04 to 1.42). The incidence of shivering was similar (3/69, 4% vs 0/71 0%, difference 4%, 95% CI=−1.1 to 9.8). One patient in the control group required reintervention for bleeding. No other major complications occurred. Conclusion FAW reduced hypothermia and improved thermal comfort. The difference in temperature between groups was modest and less than that observed in previous studies where use of FAW decreased risk of surgical complications. Therefore, it should not be considered clinically significant. Trial registration number ACTRN12616000013460.

Capnography for Moderate Sedation During Routine EGD and Colonoscopy.

Open access via a full-text view-only version To the Editor: Mehta et al. (1) concluded from their single-site randomised controlled trial of capnography during moderate sedation in routine EGD and colonoscopy that this technology does not appear to lower rates of hypoxaemia. It seems, though, that this conclusion is not consistent with the research design used.

Accuracy and precision of transcutaneous carbon dioxide monitoring: a systematic review and meta-analysis

Background Transcutaneous carbon dioxide (TcCO2) monitoring is a non-invasive alternative to arterial blood sampling. The aim of this review was to determine the accuracy and precision of TcCO2 measurements. Methods Medline and EMBASE (2000–2016) were searched for studies that reported on a measurement of PaCO2 that coincided with a measurement of TcCO2. Study selection and quality assessment (using the revised Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2)) were performed independently. The Grading Quality of Evidence and Strength of Recommendation approach was used to summarise the strength of the body of evidence. Pooled estimates of the mean bias between TcCO2 and PaCO2 and limits of agreement with outer 95% CIs (termed population limits of agreement) were calculated. Results The mean bias was −0.1 mm Hg and the population limits of agreement were −15 to 15 mm Hg for 7021 paired measurements taken from 2817 participants in 73 studies, which was outside of the clinically acceptable range (7.5 mm Hg). The lowest PaCO2 reported in the studies was 18 mm Hg and the highest was 103 mm Hg. The major sources of inconsistency were sensor location and temperature. The population limits of agreement were within the clinically acceptable range across 3974 paired measurements from 1786 participants in 44 studies that applied the sensor to the earlobe using the TOSCA and Sentec devices (−6 to 6 mm Hg). Conclusion There are substantial differences between TcCO2 and PaCO2 depending on the context in which this technology is used. TcCO2 sensors should preferentially be applied to the earlobe and users should consider setting the temperature of the sensor higher than 42°C when monitoring at other sites. Systematic review registration number PROSPERO; CRD42017057450.

High quality of evidence is uncommon in Cochrane systematic reviews in anaesthesia, critical care and emergency medicine

BACKGROUND The association between the quality of evidence in systematic reviews and authors’ conclusions regarding the effectiveness of interventions relevant to anaesthesia has not been examined. OBJECTIVE The objectives of this study were: to determine the proportion of systematic reviews in which the authors made a conclusive statement about the effect of an intervention; to describe the quality of evidence derived from outcomes in reviews that used the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) working group system for grading the quality of evidence; and to identify review characteristics associated with conclusiveness. DESIGN Cross-sectional analysis of Cochrane systematic reviews from the Anaesthesia, Critical Care and Emergency Review Group was undertaken. DATA SOURCES The Cochrane webpage was used to identify reviews for inclusion (http://.ace.cochrane.org/). ELIGIBILITY CRITERIA New and updated versions of systematic reviews published up to 17 September 2015 were eligible. Protocols for systematic reviews were excluded. RESULTS A total of 159 reviews were included. GRADE was used in 103 reviews (65%). Of these, high-level evidence for the primary outcome was identified in 11 reviews (10%). The main reasons that quality of evidence for the primary outcome was downgraded were risk of bias (n = 44; 43%) and imprecision (n = 36; 35%). Authors of 47% (n = 75) of the total number of reviews made conclusive statements about the effects of interventions. Independent predictors of conclusiveness in the subgroup of reviews with GRADE assessments were quality of evidence for the primary outcome (odds ratio 2.03; 95% confidence interval: [1.18 to 3.52] and an increasing number of studies included in reviews (OR 1.05; 95% CI: [1.01 to 1.09]). CONCLUSION It was common for conclusive statements to be made about the effects of interventions despite evidence for the primary outcome being rated less than high quality. Improving methodological quality of trials would have the greatest impact on improving the quality of evidence.