Summary Before completion of this study, there was insufficient evidence demonstrating the superiority of videolaryngoscopy compared with direct laryngoscopy for elective tracheal intubation. We hypothesised that using videolaryngoscopy for routine tracheal intubation would result in higher first‐pass tracheal intubation success compared with direct laryngoscopy. In this multicentre randomised trial, 2092 adult patients without predicted difficult airway requiring tracheal intubation for elective surgery were allocated randomly to either videolaryngoscopy with a Macintosh blade (McGrath™) or direct laryngoscopy. First‐pass tracheal intubation success was higher with the McGrath (987/1053, 94%), compared with direct laryngoscopy (848/1039, 82%); absolute risk reduction (95%CI) was 12.1% (10.9–13.6%). This resulted in a relative risk (95%CI) of unsuccessful tracheal intubation at first attempt of 0.34 (0.26–0.45; p < 0.001) for McGrath compared with direct laryngoscopy. Cormack and Lehane grade ≥ 3 was observed more frequently with direct laryngoscopy (84/1039, 8%) compared with McGrath (8/1053, 0.7%; p < 0.001) No significant difference in tracheal intubation‐associated adverse events was observed between groups. This study demonstrates that using McGrath videolaryngoscopy compared with direct laryngoscopy improves first‐pass tracheal intubation success in patients having elective surgery. Practitioners may consider using this device as first choice for tracheal intubation.
IntroductionThe direct laryngoscopy technique using a Macintosh blade is the first choice globally for most anaesthetists. In case of an unanticipated difficult airway, the complication rate increases with the number of intubation attempts. Recently, McGrath MAC (McGrath) video laryngoscopy has become a widely accepted method for securing an airway by tracheal intubation because it allows the visualisation of the glottis without a direct line of sight. Several studies and case reports have highlighted the benefit of the video laryngoscope in the visualisation of the glottis and found it to be superior in difficult intubation situations. The aim of this study was to compare the first-pass intubation success rate using the (McGrath) video laryngoscope compared with conventional direct laryngoscopy in surgical patients.Methods and analysisThe EMMA trial is a multicentre, open-label, patient-blinded, randomised controlled trial. Consecutive patients requiring tracheal intubation are randomly allocated to either the McGrath video laryngoscope or direct laryngoscopy using the Macintosh laryngoscope. The expected rate of successful first-pass intubation is 95% in the McGrath group and 90% in the Macintosh group. Each group must include a total of 1000 patients to achieve 96% power for detecting a difference at the 5% significance level. Successful intubation with the first attempt is the primary endpoint. The secondary endpoints are the time to intubation, attempts for successful intubation, the necessity of alternatives, visualisation of the glottis using the Cormack & Lehane score and percentage of glottic opening score and definite complications.Ethics and disseminationThe project was approved by the local ethics committee of the Medical Association of the Rhineland Palatine state and Westphalia-Lippe. The results of this study will be made available in the form of manuscripts for publication and presentations at national and international meetings.Trial registration numberClinicalTrials.gov NCT 02611986; pre-results.
PurposeIt is generally accepted that using a video laryngoscope is associated with an improved visualization of the glottis. However, correctly placing the endotracheal tube might be challenging. Channeled video laryngoscopic blades have an endotracheal tube already pre-loaded, allowing to advance the tube once the glottis is visualized. We hypothesized that use of a channel blade with pre-loaded endotracheal tube results in a faster intubation, compared to a curved Macintosh blade video laryngoscope.MethodsAfter ethical approval and informed consent, patients were randomized to receive endotracheal Intubation with either the King Vision® video laryngoscope with curved blade (control) or channeled blade (channeled). Success rate, evaluation of the glottis view (percentage of glottic opening (POGO), Cormack&Lehane (C&L)) and intubating time were evaluated.ResultsOver a two-month period, a total of 46 patients (control n = 23; channeled n = 23) were examined. The first attempt success rates were comparable between groups (control 100% (23/23) vs. channeled 96% (22/23); p = 0.31). Overall intubation time was significantly shorter with control (median 40 sec; IQR [24–58]), compared to channeled (59 sec [40–74]; p = 0.03). There were no differences in glottis visualization between groups.ConclusionCompared with the King Vision channeled blade, time for tracheal intubation was shorter with the control group using a non-channeled blade. First attempt success and visualization of the glottis were comparable. These data do not support the hypothesis that a channeled blade is superior to a curved video laryngoscopic blade without tube guidance.Trial registrationClinicalTrials.gov NCT02344030
Summary Non‐invasive haemoglobin measurement using absolute values lacks the precision to be the sole basis for the treatment of pre‐operative anaemia. However, it can possibly serve as a screening test, indexing ‘anaemia’ with high sensitivity when values remain under prespecified cut‐off values. Based on previous data, non‐invasive haemoglobin cut‐off values (146 g.l−1 for women and 152 g.l−1 for men) detect true anaemia with 99% sensitivity. An index test with these prespecified cut‐off values was verified by prospective measurement of non‐invasive and invasive haemoglobin pre‐operatively in elective surgical patients. In 809 patients, this showed an estimated sensitivity (95%CI) of 98.9% (94.1–99.9%) in women and 96.4% (91.0–99.0%) in men. This saved invasive blood tests in 9% of female and 28% of male patients. In female patients, a lower non‐invasive haemoglobin cut‐off value (138 g.l−1) would save 28% of invasive blood tests with a sensitivity of 95%. The target 99% sensitivity would be reached by non‐invasive haemoglobin cut‐off values of 152 g.l−1 in female and 162 g.l−1 in male patients, saving 3% and 9% of invasive blood tests, respectively. Bias and limits of agreement between non‐invasive and laboratory haemoglobin levels were 2 and − 25 to 28 g.l−1, respectively. Patient and measurement characteristics did not influence the agreement between non‐invasive and laboratory haemoglobin levels. Although sensitivity was very high, the index test using prespecified cut‐off values just failed to reach the target sensitivity to detect true anaemia. Nevertheless, with respect to blood‐sparing effects, the use of the index test in men may be clinically useful, while an index test with a lower cut‐off (132 g.l−1) could be more clinically appropriate in women.
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