Downloaded from http://emj.bmj.com/ on September 2, 2017 - Published by group.bmj.com Review Capnography for procedural sedation in the ED: a systematic review Charlotte Dewdney,1 Margaret MacDougall,2 Rachel Blackburn,3 Gavin Lloyd,4 Alasdair Gray5 ► Additional material is ABSTRACT carbon dioxide in an exhaled breath, may be used published online only. To view Introduction Procedural sedation and analgesia (PSA) as an additional parameter of a patient’s ventilation please visit the journal online (http://dx.doi.org/10.1136/ is commonplace in the ED. Previous studies have to identify adverse events during procedural sed- emermed-2015-204944). identified capnography as a reliable indicator of PSA- ation. This is accomplished by measuring changes in induced respiratory depression. This review investigates end-tidal carbon dioxide (ETCO2). Previous studies 1College of Medicine and the potential effect on patient safety of the use of have identified capnography as a useful diagnostic Veterinary Medicine, University 3 of Edinburgh, Edinburgh, UK capnography in addition to standard monitoring for measure of PSA-related adverse events. The joint 2Centre for Population adult patients undergoing PSA in the ED. Royal College of Anaesthetists and the Royal Health Sciences, University of Methods MEDLINE, Embase, Scopus, CINAHL and College of Emergency Medicine procedural sedation Edinburgh, Edinburgh, UK Google Scholar were searched systematically for ED guidelines deem its use mandatory for deep or 3Department of Emergency Medicine, Royal Infirmary of studies using capnography during PSA. Data extraction dissociative sedation and recommended for lighter 2 Edinburgh, Edinburgh, UK was performed by two independent authors. Using levels. It is also advocated by the American College 4Department of Emergency MedCalc V.13.3.3 and Meta-DiSc V.1.4, data were of Emergency Physicians policy (Level B recommen- Medicine, Royal Devon & Exeter aggregated under the random-effects model and dation).4 However, evidence of its benefit in redu- Hospital, Exeter, UK 5 heterogeneity was assessed using Cochran’s Q-test and cing adverse events and improving patient safety is Emergency Medicine Research 2 Group Edinburgh (EMeRGE), the I statistic. uncertain. Department of Emergency Results Of the 737 studies that were screened, 7 First, there is no universally agreed definition for Medicine, Royal Infirmary of studies met the eligibility criteria, representing a total of a PSA-related adverse event, making it difficult to Edinburgh, Edinburgh, UK 662 patients. The aggregate diagnostic accuracy for identify and report adverse events accurately and capnography identifying an adverse event included a consistently between studies. Additionally, there are Correspondence to diagnostic OR of approximately 6 (OR: 5.87; 95% CI different levels of sedation: deeper levels are asso- Dr Charlotte Dewdney, College 5 of Medicine and Veterinary 2.41 to 14.3; p<0.001), sensitivity 0.82 (95% CI 0.76 ciated with an increased rate of adverse effects; Medicine, University of to 0.87), specificity 0.6 (95% CI 0.55 to 0.64), negative this needs to be accounted for when comparing Edinburgh, Edinburgh, EH16 likelihood ratio 0.3 (95% CI 0.12 to 0.75) and positive studies. Moreover, there is inconsistent oxygen 4SA, UK; likelihood ratio 1.89 (95% CI 1.53 to 2.34). There was delivery before and during procedures, making charlottedewdney@doctors. fi fi org.uk a lack of statistical evidence for a difference in the interpretation of study ndings dif cult. Some proportion of adverse events detected when studies have found that changes in ETCO2 are not Received 16 April 2015 capnography was used in addition to standard related to adverse outcome in PSA,67whereas Revised 28 July 2016 monitoring (48.8% (95% CI 32.85 to 64.92)) compared others suggest that capnography is able to identify Accepted 3 August 2016 with chance alone (50%). the onset of adverse events ahead of changes in Published Online First 89 26 August 2016 Conclusions There is no firm evidence that standard monitoring. capnography provides additional safety compared with This review investigates the potential effect on standard monitoring alone during PSA in adults in the patient safety of the use of capnography in addition ED. There is a paucity of published research involving to standard monitoring for adult patients undergo- preoxygenated patients who remain on high-flow oxygen ing PSA in the ED. The review focuses on separate throughout PSA. Well-powered randomised controlled markers of patient safety: first, the diagnostic accur- trials, employing an accepted adverse event reporting acy of capnography alone in detecting PSA-related tool in such patients, are required. Until then, we adverse events and second, the ability of capnogra- advocate continued compliance with current professional phy to detect such events before standard monitor- recommendations for the use of capnography during PSA ing. Finally, the review aims to evaluate the in adults in the ED. physician interventions based on capnography data. MATERIALS AND METHODS INTRODUCTION Reporting of this systematic review followed the Procedural sedation and analgesia (PSA) is com- Preferred Reporting Items for Systematic Reviews monplace in the ED. PSA involves administering and Meta-Analyses (PRISMA) statement.10 sedative medications with or without analgesics to induce a depressed level of consciousness, enabling Search strategy clinicians to perform procedures effectively while An electronic search of MEDLINE and Embase via providing pain relief and allowing the patient to Ovid; Scopus; Cumulative Index to Nursing and maintain airway control independently.1 Patients Allied Health Literature (CINAHL) via EBSCO; and 2 To cite: Dewdney C, should be monitored closely for adverse effects. Google Scholar was conducted. These databases MacDougall M, Blackburn R, Standard monitoring includes pulse rate, ECG, BP, were searched from their inception to 26 July 2015. et al. Emerg Med J oxygen saturation and RR. Capnography, the non- ‘Capnography’ was included as a search term for 2017;34:476–484. invasive measurement of the partial pressure of publications dating from 1997, when this particular 476 Dewdney C, et al. Emerg Med J 2017;34:476–484. doi:10.1136/emermed-2015-204944 Downloaded from http://emj.bmj.com/ on September 2, 2017 - Published by group.bmj.com Review term was first recognised as a medical subject heading (MeSH) the Grading of Recommendations Assessment, Development term; synonymous search terms were included to capture and Evaluation (GRADE) system.16 pre-1997 publications11 (see online supplementary appendix 1 for search strategies). Database searching was supplemented with Statistical analysis identification of references from relevant papers; hand-searching Statistical analysis was performed using MedCalc V.13.3.3 of journals; identification of relevant conference proceedings and (MedCalc Software, Ostend, Belgium) unless stated otherwise. searching of clinical trial registries. No restrictions, including lan- In the meta-analysis evaluating diagnostic accuracy, ORs were guage or publication type, were applied. calculated as OR=ad/bc, where a is the number of true positives (adverse events detected as such by ETCO2), b the number of fi Study selection false positives (events misclassi ed as adverse events by ETCO2), c the number of false negatives (adverse events undetected by Papers were initially screened and excluded on the basis of the ETCO ) and d the number of true negatives (absence of adverse relevance of their titles and abstracts. All randomised control 2 events detected as such by ETCO ).3 Fixed-effects (Mantel– trials (RCTs), quasi-randomised control trials (qRCTs) and 2 Haenszel method)17 and random-effects (Der Simonian–Laird observational (including cohort) studies that included an analysis method)18 models were used to estimate aggregate ORs. Using of capnography during PSA were included. Published systematic these tests, the significance of the aggregate ORs was assessed in reviews were analysed for their potential to be extended or terms of the null hypothesis that OR=1, using the z-test. revised but were excluded from the review and meta-analysis. In assessing the potential usefulness of capnography in detect- All other study types were excluded. All potentially relevant ing adverse events for patients undergoing PSA, we assumed the studies were retrieved as full manuscripts. Two independent recommended requirement that the diagnostic OR should be reviewers (CD and RB) applied predefined inclusion and exclu- ‘well above 20’.19 sion criteria (table 1) to remove ineligible or duplicate studies. Further evaluation of the diagnostic utility of capnography Disagreements were resolved through arbitration by a third was carried out by calculating the aggregate positive and nega- independent reviewer (AG). tive likelihood ratios using the random effects model. The sensi- tivity, specificity, positive likelihood ratio (LR) and negative LR Data extraction were determined for each included study and in aggregate form Data extraction was performed using a data collection form using the test accuracy software Meta-DiSc (V.1.4).20 12 published by the Cochrane Collaboration. No eligible study Using a binomial model, a meta-analysis delineating the pro- required language translation. portion of adverse events identified by changes in capnography compared with changes in standard monitoring was calculated, Quality assessment with 0.5 (50%) taken to represent the threshold