C.V. Rosenstock

Avoidance of neuromuscular blocking agents may increase the risk of difficult tracheal intubation: a cohort study of 103 812 consecutive adult patients recorded in the Danish Anaesthesia Database

BACKGROUNDnPrevious studies indicate that avoiding neuromuscular blocking agents (NMBAs) may be a risk factor for difficult tracheal intubation (DTI). We investigated whether avoiding NMBA was associated with DTI.nnnMETHODSnA cohort of 103,812 consecutive patients planned for tracheal intubation by direct laryngoscopy was retrieved from the Danish Anaesthesia Database. We used an intubation score based upon the number of attempts, change from direct laryngoscopy to a more advanced technique, or intubation by a different operator. We retrieved data on age, sex, ASA physical status classification, priority of surgery, time of surgery, previous DTI, modified Mallampati score, BMI, and the use of NMBA. Using logistic regression, we assessed whether avoiding NMBA was associated with DTI.nnnRESULTSnThe frequency of DTI was 5.1 [95% confidence interval (CI): 5.0-5.3]%. In a univariate analysis, avoiding NMBA was associated with DTI, odds ratio (OR) 1.52 (95% CI: 1.43-1.61)%, P<0.0001. Using multivariate analysis, avoiding NMBA was associated with DTI, OR 1.48 (95% CI: 1.39-1.58), P<0.0001. Among patients intubated using NMBA, a multivariate analysis identified patients anaesthetized with only non-depolarizing NMBA to be more at risk for DTI than those anaesthetized with depolarizing NMBA alone.nnnCONCLUSIONSnAvoiding NMBA may increase the risk of DTI. However, confounding by indication may be a problem in this observational study and systematic reviews with meta-analysis or more randomized clinical trials are needed.

Diagnostic accuracy of anaesthesiologists’ prediction of difficult airway management in daily clinical practice: a cohort study of 188 064 patients registered in the Danish Anaesthesia Database

Both the American Society of Anesthesiologists and the UK NAP4 project recommend that an unspecified pre‐operative airway assessment be made. However, the choice of assessment is ultimately at the discretion of the individual anaesthesiologist. We retrieved a cohort of 188 064 cases from the Danish Anaesthesia Database, and investigated the diagnostic accuracy of the anaesthesiologists’ predictions of difficult tracheal intubation and difficult mask ventilation. Of 3391 difficult intubations, 3154 (93%) were unanticipated. When difficult intubation was anticipated, 229 of 929 (25%) had an actual difficult intubation. Likewise, difficult mask ventilation was unanticipated in 808 of 857 (94%) cases, and when anticipated (218 cases), difficult mask ventilation actually occurred in 49 (22%) cases. We present a previously unpublished estimate of the accuracy of anaesthesiologists’ prediction of airway management difficulties in daily routine practice. Prediction of airway difficulties remains a challenging task, and our results underline the importance of being constantly prepared for unexpected difficulties.

A documented previous difficult tracheal intubation as a prognostic test for a subsequent difficult tracheal intubation in adults.

We investigated the diagnostic accuracy of a documented previous difficult tracheal intubation as a stand‐alone test for predicting a subsequent difficult intubation. Our assessment included patients from the Danish Anaesthesia Database who were scheduled for tracheal intubation by direct laryngoscopy. We used a four‐point scale to grade the tracheal intubation. A previous difficult intubation was defined according to the presence of a record documenting a difficult penultimate tracheal intubation‐score for the 15u2003499 patients anaesthetised more than once. Our assessment demonstrates that a documented history of previous difficult or failed intubation using direct laryngoscopy are strong predictors of a subsequent difficult or failed intubation and may identify 30% of these patients. Although previous investigators have reported predictive values that exceed our findings markedly, a documented previous difficult or failed tracheal intubation appears in everyday anaesthetic practice to be a strong predictor of a subsequent difficult tracheal intubation.

Effects of using the simplified airway risk index vs usual airway assessment on unanticipated difficult tracheal intubation - a cluster randomized trial with 64,273 participants

BACKGROUNDnUnanticipated difficult intubation remains a challenge in anaesthesia. The Simplified Airway Risk Index (SARI) is a multivariable risk model consisting of seven independent risk factors for difficult intubation. Our aim was to compare preoperative airway assessment based on the SARI with usual airway assessment.nnnMETHODSnFrom 01.10.2012 to 31.12.2013, 28 departments were cluster-randomized to apply the SARI model or usual airway assessment. The SARI group implemented the SARI model. The Non-SARI group continued usual airway assessment, thus reflecting a group of anaesthetists heterogeneous individual airway assessments. Preoperative prediction of difficult intubation and actual intubation difficulties were registered in the Danish Anaesthesia Database for both groups. Patients who were preoperatively scheduled for intubation by advanced techniques (e.g. video laryngoscopy; flexible optic scope) were excluded from the primary analysis. Primary outcomes were the proportions of unanticipated difficult and unanticipated easy intubation.nnnRESULTSnA total of 26 departments (15 SARI and 11 Non-SARI) and 64 273 participants were included. In the primary analyses 29 209 SARI and 30 305 Non-SARI participants were included.In SARI departments 2.4% (696) of the participants had an unanticipated difficult intubation vs 2.4% (723) in Non-SARI departments. Odds ratio (OR) adjusted for design variables was 1.03 (95% CI: 0.77-1.38). The proportion of unanticipated easy intubation was 1.42% (415) in SARI departments vs 1.00% (302) in Non-SARI departments. Adjusted OR was 1.26 (0.68-2.34).nnnCONCLUSIONSnUsing the SARI compared with usual airway assessment we detected no statistical significant changes in unanticipated difficult- or easy intubations.nnnCLINICAL TRIAL REGISTRATIONnNCT01718561.

Emergency surgical airway management in Denmark: a cohort study of 452 461 patients registered in the Danish Anaesthesia Database

BACKGROUNDnThe emergency surgical airway (ESA) is the final option in difficult airway management. We identified ESA procedures registered in the Danish Anaesthesia Database (DAD) and described the performed airway management.nnnMETHODSnWe extracted a cohort of 452 461 adult patients undergoing general anaesthesia and tracheal intubation from the DAD from June 1, 2008 to March 15, 2014. Difficult airway management involving an ESA was retrieved for analysis and compared with hospitals files. Two independent reviewers evaluated airway management according to the ASAs2003 practice guideline for difficult airway management.nnnRESULTSnIn the DAD cohort 27 out of 452 461 patients had an ESA representing an incidence of 0.06 events per thousand (95% CI; 0.04 to 0.08). A total of 12 149/452 461 patients underwent Ear-Nose and Throat (ENT) surgery, giving an ESA incidence among ENT patients of 1.6 events per thousand (95% CI; 1.0-2.4). A Supraglottic Airway Device and/or the administration of a neuromuscular blocking agent before ESA were used as a rescue in 6/27 and 13/27 of the patients, respectively. In 19/27 patients ENT surgeons performed the ESAs and anaesthetists attempted 6/27 of the ESAs of which three failed. Reviewers evaluated airway management as satisfactory in 10/27 patients.nnnCONCLUSIONSnThe incidence of ESA in the DAD cohort was 0.06 events per thousand. Among ENT patients, the ESA Incidence was 1.6 events per thousand. Airway management was evaluated as satisfactory for 10/27 of the patients. ESA performed by anaesthetists failed in half of the patients.

Prediction of difficult mask ventilation using a systematic assessment of risk factors vs. existing practice - a cluster randomised clinical trial in 94,006 patients.

We compared implementation of systematic airway assessment with existing practice of airway assessment on prediction of difficult mask ventilation. Twenty‐six departments were cluster‐randomised to assess eleven risk factors for difficult airway management (intervention) or to continue with their existing airway assessment (control). In both groups, patients predicted as a difficult mask ventilation and/or difficult intubation were registered in the Danish Anaesthesia Database, with a notational summary of airway management. The trials primary outcome was the respective incidence of unpredicted difficult and easy mask ventilation in the two groups. Among 94,006 patients undergoing mask ventilation, the incidence of unpredicted difficult mask ventilation in the intervention group was 0.91% and 0.88% in the control group; (OR) 0.98 (95% CI 0.66–1.44), p = 0.90. The incidence of patients predicted difficult to mask ventilate, but in fact found to be easy (‘falsely predicted difficult’) was 0.64% vs. 0.35% (intervention vs. control); OR 1.56 (1.01–2.42), p = 0.045. In the intervention group, 86.3% of all difficult mask ventilations were not predicted, compared with a higher proportion 91.2% in the control group, OR 0.61 (0.41–0.91), p = 0.016. The systematic intervention did not alter the overall incidence of unpredicted difficult mask ventilations, but of the patients who were found to be difficult to mask ventilate, the proportion predicted was higher in the intervention group than in the control group. However, this was at a ‘cost’ of increasing the number of mask ventilations falsely predicted to be difficult.

Effects of avoidance or use of neuromuscular blocking agents on outcomes in tracheal intubation: a Cochrane systematic review

Abstract Cohort studies have indicated that avoidance of neuromuscular blocking agents (NMBA) is a risk factor for difficult tracheal intubation. However, the impact of avoiding NMBA on tracheal intubation, possible adverse effects, and postoperative discomfort has not been evaluated in a systematic review of randomised trials. We searched several databases for trials published until January 2017. We included randomised controlled trials comparing the effect of avoiding vs using NMBA. Two independent authors assessed risk of bias and extracted data. The risk of random errors was assessed by trial sequential analysis (TSA). We included 34 trials (3565 participants). In the four trials judged to have low risk of bias, there was an increased risk of difficult tracheal intubation with no use of NMBA [random‐effects model, risk ratio (RR) 13.27, 95% confidence interval (CI) 8.19–21.49, P<0.00001, TSA‐adjusted CI 1.85–95.04]. The result was confirmed when including all trials, (RR 5.00, 95% CI 3.49–7.15, P<0.00001, TSA‐adjusted CI 1.20–20.77). There was a significant risk of upper airway discomfort or injury by avoiding NMBA (RR=1.37, 95% CI 1.09–1.74, P=0.008, TSA‐adjusted CI 1.00–1.86). None of the trials reported mortality. Avoiding NMBA was significantly associated with difficult laryngoscopy, (RR 2.54, 95% CI 1.53–4.21, P=0.0003, TSA‐adjusted CI 0.27–21.75). In a clinical context, one must balance arguments for using NMBA when performing tracheal intubation.

The Danish Anaesthesia Database

Aim of database The aim of the Danish Anaesthesia Database (DAD) is the nationwide collection of data on all patients undergoing anesthesia. Collected data are used for quality assurance, quality development, and serve as a basis for research projects. Study population The DAD was founded in 2004 as a part of Danish Clinical Registries (Regionernes Kliniske Kvalitetsudviklings Program [RKKP]). Patients undergoing general anesthesia, regional anesthesia with or without combined general anesthesia as well as patients under sedation are registered. Data are retrieved from public and private anesthesia clinics, single-centers as well as multihospital corporations across Denmark. In 2014 a total of 278,679 unique entries representing a national coverage of ~70% were recorded, data completeness is steadily increasing. Main variable Records are aggregated for determining 13 defined quality indicators and eleven defined complications all covering the anesthetic process from the preoperative assessment through anesthesia and surgery until the end of the postoperative recovery period. Descriptive data Registered variables include patients’ individual social security number (assigned to all Danes) and both direct patient-related lifestyle factors enabling a quantification of patients’ comorbidity as well as variables that are strictly related to the type, duration, and safety of the anesthesia. Data and specific data combinations can be extracted within each department in order to monitor patient treatment. In addition, an annual DAD report is a benchmark for departments nationwide. Conclusion The DAD is covering the anesthetic process for the majority of patients undergoing anesthesia in Denmark. Data in the DAD are increasingly used for both quality and research projects.

Detailed statistical analysis plan for the difficult airway management (DIFFICAIR) trial

BackgroundPreoperative airway assessment in Denmark is based on a non-specific clinical assessment left to the discretion of the responsible anesthesiologist. The DIFFICAIR trial compares the effect of using a systematic and consistent airway assessment versus a non-specific clinical assessment on the frequency of unanticipated difficult airway management.To prevent outcome bias and selective reporting, we hereby present a detailed statistical analysis plan as an amendment (update) to the previously published protocol for the DIFFICAIR trial.Method/DesignThe DIFFICAIR trial is a stratified, parallel group, cluster (clusteru2009=u2009department) randomized multicenter trial involving 28 departments of anesthesia in Denmark randomized to airway assessment either by the Simplified Airway Risk Index (SARI) or by a usual non-specific assessment. Data from patients’ preoperative airway assessment are registered in the Danish Anesthesia Database. An objective score for intubation grading the severity, that is the severity of the intubations, as well as the frequency of unanticipated difficult intubation, is measured for each group.Primary outcome measures are the fraction of unanticipated difficult and easy intubations.The database is programmed so that the registration of the SARI is mandatory for the intervention group but invisible to controls.Data recruitment was commenced in October 2012 and ended in ultimo December 2013.ConclusionWe intend to increase the transparency of the data analyses regarding the DIFFICAIR trial by an a priori publication of a statistical analysis plan.Trial registrationClinicalTrials.gov: NCT01718561.

Avoidance vs use of neuromuscular blocking agent for improving conditions during tracheal intubation: a Cochrane systematic review

Abstract Cohort studies have indicated that avoidance of neuromuscular blocking agents (NMBA) is a risk factor for difficult tracheal intubation. However, the impact of avoiding NMBA on tracheal intubation, possible adverse effects, and postoperative discomfort has not been evaluated in a systematic review of randomised trials. We searched several databases for trials published until January 2017. We included randomised controlled trials comparing the effect of avoiding vs using NMBA. Two independent authors assessed risk of bias and extracted data. The risk of random errors was assessed by trial sequential analysis (TSA). We included 34 trials (3565 participants). In the four trials judged to have low risk of bias, there was an increased risk of difficult tracheal intubation with no use of NMBA [random‐effects model, risk ratio (RR) 13.27, 95% confidence interval (CI) 8.19–21.49, P<0.00001, TSA‐adjusted CI 1.85–95.04]. The result was confirmed when including all trials, (RR 5.00, 95% CI 3.49–7.15, P<0.00001, TSA‐adjusted CI 1.20–20.77). There was a significant risk of upper airway discomfort or injury by avoiding NMBA (RR=1.37, 95% CI 1.09–1.74, P=0.008, TSA‐adjusted CI 1.00–1.86). None of the trials reported mortality. Avoiding NMBA was significantly associated with difficult laryngoscopy, (RR 2.54, 95% CI 1.53–4.21, P=0.0003, TSA‐adjusted CI 0.27–21.75). In a clinical context, one must balance arguments for using NMBA when performing tracheal intubation.