Measurement of forces applied during Macintosh direct laryngoscopy compared with GlideScope® videolaryngoscopy

A prospective randomized controlled study to evaluate and compare GlideScope with Macintosh laryngoscope for ease of endotracheal intubation in adult patients undergoing elective surgery under general anesthesia

Background:

The aim of the study was to compare the ease the intubation using GlideScope video laryngoscope and Macintosh laryngoscope in adult patients undergoing elective surgery under general anesthesia.

Materials and Methods:

A total of 200 American Society of Anesthesiologists I–II patients of either sex, in the age group of 18–60 years were included in the study. Patients were randomly allocated to two groups. We assessed ease of intubation depending on time to tracheal intubation, number of attempts, glottic view (Cormack–Lehane grade [CL grade] and percentage of glottis opening [POGO]) and intubation difficulty score (IDS), hemodynamic variables and any intra- and post-operative adverse events.

Results:

The rate of successful endotracheal intubation (ETI) in both groups was 100% in the first attempt. The time required for successful ETI was 24.89 ± 5.574 in Group G and 20.68 ± 3.637 in Group M (P < 0.001) found to be statistically significant. There was significant improvement in glottic view with GlideScope (as assessed by POGO score 66.71 ± 29.929 and 94.40 ± 10.476 in group G and 75.85 ± 26.969 and 74.20 ± 29.514 Group M and CL grading [P < 0.001]). A comparison of mean IDS between two groups revealed intubation was easier with the use of GlideScope. The hemodynamic response to intubation was significantly lesser with the use of GlideScope when compared with Macintosh laryngoscope. The incidence of adverse events, though minor like superficial lip or tongue bleed, was similar in two groups.

Conclusions:

GlideScope offers superiority over Macintosh laryngoscope in terms of laryngeal views and the difficulty encountered at ETI in an unselected population.

Videolaryngoscopy vs. Macintosh laryngoscopy for double-lumen tube intubation in thoracic surgery: a systematic review and meta-analysis

Double-lumen intubation is more difficult than single-lumen tracheal intubation. Videolaryngoscopes have many advantages in airway management. However, the advantages of videolaryngoscopy for intubation with a double-lumen tube remain controversial compared with traditional Macintosh laryngoscopy. In this study, we searched MEDLINE, Embase, Cochrane Library and the Web of Science for randomised controlled trials comparing videolaryngoscopy with Macintosh laryngoscopy for double-lumen tube intubation. We found that videolaryngoscopy provided a higher success rate at first attempt for double-lumen tube intubation, with an odds ratio (95%CI) of 2.77 (1.92-4.00) (12 studies, 1215 patients, moderate-quality evidence, p < 0.00001), as well as a lower incidence of oral, mucosal or dental injuries during double-lumen tube intubation, odds ratio (95%CI) 0.36 (0.15-0.85) (11 studies, 1145 patients, low-quality evidence, p = 0.02), and for postoperative sore throat, odds ratio (95%CI) 0.54 (0.36-0.81) (7 studies, 561 patients, moderate-quality evidence, p = 0.003), compared with Macintosh laryngoscopy. There were no significant differences in intubation time, with a standardised mean difference (95%CI) of -0.10 (-0.62 to 0.42) (14 studies, 1310 patients, very low-quality evidence, p = 0.71); and the incidence of postoperative voice change, odds ratio (95%CI) 0.53 (0.21-1.31) (7 studies, 535 patients, low-quality evidence, p = 0.17). Videolaryngoscopy led to a higher incidence of malpositioned double-lumen tube, with an odds ratio (95%CI) of 2.23 (1.10-4.52) (six studies, 487 patients, moderate-quality evidence, p = 0.03).

The pressure exerted on the tongue during intubation with simultaneous cervical spine immobilisation: a comparison between four videolaryngoscopes and the Macintosh laryngoscope-a manikin study

Excessive pressures exerted on the tongue during intubation may be associated with serious complications and may make intubation more difficult. The aim of this study was to evaluate five different intubating devices in the hands of experienced anaesthetists during simulated conditions of reduced cervical spine mobility. Forty senior anaesthetists participated in the study (female = 18, male = 22). The mean pressure exerted on the tongue during intubation was recorded with a standard manometer. The overall intubation success rate as well as the difference in exerted pressures between female and male anaesthetists were also assessed. The five studied devices were used by each participant and they were randomly chosen. Each anaesthetists participating in the study had over 15 years of clinical anaesthetic practice. The mean pressure exerted on the tongue during intubation was significantly lower when the videolaryngoscopes (VLs) were used (p < 0.0001 for each of the studied VL). There were failed intubation attempts with all of the studied devices, the highest failure rate was in the Airtraq® group, 10 in 40 (25%). Female anaesthetists exerted lower pressures during intubation with all studied devices (except the Airtraq®). However, the difference was only significant for the Macintosh laryngoscope (p = 0.0083). The blades of VLs exerted lower pressures on the tongue during intubation than the Macintosh laryngoscope blade. Their use may be associated with less complications. Furthermore, male anaesthetists exerted higher pressures on the soft tissues although this was neither statistically nor clinically significant. There was higher failed intubation rate in the male anaesthetist group.

Incidence and severity of postoperative sore throat: a randomized comparison of Glidescope with Macintosh laryngoscope

BACKGROUND

Postoperative sore throat (POST) is a common problem following endotracheal (ET) intubation during general anesthesia. The objective was to compare the incidence and severity of POST during routine intubation with Glidescope (GL) and Macintosh laryngoscope (MCL).

METHODS

One hundred forty adult patients ASA I and II with normal airway, scheduled to undergo elective surgery under GA requiring ET intubation were enrolled in this prospective randomized study and were randomly divided in two groups, GL and MCL. Incidence and severity of POST was evaluated at 0, 6, 12 and 24 h after surgery.

RESULTS

At 0 h, the incidence of POST was more in MCL than GL (n = 41 v.s n = 22, P = 0.001), and also at 6 h after surgery (n = 37 v.s n = 23, P = 0.017). Severity of POST was more at 0, 6 and 12 h after surgery in MCL (P < 0.001, P = 0.001, P = 0.004 respectively).

CONCLUSIONS

Routine use of GL for ET tube placement results in reduction in the incidence and severity of POST compared to MCL.

TRIAL REGISRATION

ClinicalTrials.gov NCT02848365 . Retrospectively Registered (Date of registration: July, 2016).

Nociceptive stimulation during Macintosh direct laryngoscopy compared with McGrath Mac videolaryngoscopy: A randomized trial using indirect evaluation using an automated administration of propofol and remifentanil

BACKGROUND

Decrease of the nociceptive stimulation induced by laryngoscopy could be an advantage for patients without risk of difficult intubation. The present study aimed to compare the difference in nociceptive stimulation between the use of a conventional laryngoscope or of a videolaryngoscope. Amount of nociception was assessed indirectly using the peak remifentanil concentration determined by a closed-loop administration of propofol and remifentanil with bispectral index (BIS) as the input signal (target 50).

METHODS

A prospective single-center randomized study was performed including surgical patients without predictable risk of difficult mask ventilation or of difficult tracheal intubation. Forty consecutive surgery patients were randomly assigned to CL group (conventional laryngoscope) or VL group (McGrath Mac videolaryngoscope). Induction of anesthesia was performed automatically using the closed-loop system and myorelaxation with atracurium. The allocation was revealed just before tracheal intubation. The primary outcome was the peak plasma remifentanil concentration observed during the 5-minute period which followed intubation.

RESULTS

Sixteen patients in the CL group and 11 in the VL group were analyzed. Plasmatic remifentanil and propofol concentrations were similar in both groups either before tracheal intubation or during the 5 minutes following intubation. There was a nonsignificant between-group difference (P = .09) for the peak concentration of remifentanil. A comparable result was observed for other outcomes except for the heart rate which increased in the CL group.

CONCLUSION

Use of the videolaryngoscope McGrath Mac did not reduce the nociceptive stimulation induced during intubation as evaluated by the automatically administered remifentanil concentration.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02245789.

Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation

BACKGROUND

Successful tracheal intubation during general anaesthesia traditionally requires a line of sight to the larynx attained by positioning the head and neck and using a laryngoscope to retract the tongue and soft tissues of the floor of the mouth. Difficulties with intubation commonly arise, and alternative laryngoscopes that use digital and/or fibreoptic technology have been designed to improve visibility when airway difficulty is predicted or encountered. Among these devices, a rigid videolaryngoscope (VLS) uses a blade to retract the soft tissues and transmits a lighted video image to a screen.

OBJECTIVES

Our primary objective was to assess whether use of videolaryngoscopy for tracheal intubation in adults requiring general anaesthesia reduces risks of complications and failure compared with direct laryngoscopy. Our secondary aim was to assess the benefits and risks of these devices in selected population groups, such as adults with obesity and those with a known or predicted difficult airway.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase on 10 February 2015. Our search terms were relevant to the review question and were not limited by outcomes. We carried out clinical trials register searches and forward and backward citation tracking. We reran the search on 12 January 2016; we added potential new studies of interest from the 2016 search to a list of 'Studies awaiting classification', and we will incorporate these studies into the formal review during the review update.

SELECTION CRITERIA

We considered all randomized controlled trials and quasi-randomized studies with adult patients undergoing laryngoscopy performed with a VLS or a Macintosh laryngoscope in a clinical, emergency or out-of-hospital setting. We included parallel and cross-over study designs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data, consulting a third review author to resolve disagreements. We used standard Cochrane methodological procedures, including assessment of risk of bias.

MAIN RESULTS

We included 64 studies identified during the 2015 search that enrolled 7044 adult participants and compared a VLS of one or more designs with a Macintosh laryngoscope. We identified 38 studies awaiting classification and seven ongoing studies. Of the 64 included studies, 61 included elective surgical patients, and three were conducted in an emergency setting. Among 48 studies that included participants without a predicted difficult airway, 15 used techniques to simulate a difficult airway. Seven recruited participants with a known or predicted difficult airway, and the remaining studies did not specify or included both predicted and not predicted difficult airways. Only two studies specifically recruited obese participants. It was not possible to blind the intubator to the device, and we noted a high level of inevitable heterogeneity, given the large number of studies.Statistically significantly fewer failed intubations were reported when a VLS was used (Mantel-Haenszel (M-H) odds ratio (OR), random-effects 0.35, 95% confidence Interval (CI) 0.19 to 0.65; 38 studies; 4127 participants), and fewer failed intubations occurred when a VLS was used in participants with an anticipated difficult airway (M-H OR, random-effects 0.28, 95% CI 0.15 to 0.55; six studies; 830 participants). We graded the quality of this evidence as moderate on the basis of the GRADE system. Failed intubations were fewer when a VLS was used in participants with a simulated difficult airway (M-H OR, random-effects 0.18, 95% CI 0.04 to 0.77; nine studies; 810 participants), but groups with no predicted difficult airway provided no significant results (M-H OR, random-effects 0.61, 95% CI 0.22 to 1.67; 19 studies; 1743 participants).Eight studies reported on hypoxia, and only three of these described any events; results showed no differences between devices for this outcome (M-H OR, random-effects 0.39, 95% CI 0.10 to 1.44; 1319 participants). Similarly, few studies reported on mortality, noting no differences between devices (M-H OR, fixed-effect 1.09, 95% CI 0.65 to 1.82; two studies; 663 participants), and only one study reporting on the occurrence of respiratory complications (78 participants); we graded these three outcomes as very low quality owing to lack of data. We found no statistically significant differences between devices in the proportion of successful first attempts (M-H OR, random-effects 1.27, 95% CI 0.77 to 2.09; 36 studies; 4731 participants) nor in those needing more than one attempt. We graded the quality of this evidence as moderate. Studies reported no statistically significant differences in the incidence of sore throat in the postanaesthesia care unit (PACU) (M-H OR, random-effects 1.00 (95% CI 0.73 to 1.38); 10 studies; 1548 participants) nor at 24 hours postoperatively (M-H OR random-effects 0.54, 95% CI 0.27 to 1.07; eight studies; 844 participants); we graded the quality of this evidence as moderate. Data combined to include studies of cross-over design revealed statistically significantly fewer laryngeal or airway traumas (M-H OR, random-effects 0.68, 95% CI 0.48 to 0.96; 29 studies; 3110 participants) and fewer incidences of postoperative hoarseness (M-H OR, fixed-effect 0.57, 95% CI 0.36 to 0.88; six studies; 527 participants) when a VLS was used. A greater number of laryngoscopies performed with a VLS achieved a view of most of the glottis (M-H OR, random-effects 6.77, 95% CI 4.17 to 10.98; 22 studies; 2240 participants), fewer laryngoscopies performed with a VLS achieved no view of the glottis (M-H OR, random-effects 0.18, 95% CI 0.13 to 0.27; 22 studies; 2240 participants) and the VLS was easier to use (M-H OR, random-effects 7.13, 95% CI 3.12 to 16.31; seven studies; 568 participants).Although a large number of studies reported time required for tracheal intubation (55 studies; 6249 participants), we did not present an effects estimate for this outcome owing to the extremely high level of statistical heterogeneity (I2 = 96%).

AUTHORS' CONCLUSIONS

Videolaryngoscopes may reduce the number of failed intubations, particularly among patients presenting with a difficult airway. They improve the glottic view and may reduce laryngeal/airway trauma. Currently, no evidence indicates that use of a VLS reduces the number of intubation attempts or the incidence of hypoxia or respiratory complications, and no evidence indicates that use of a VLS affects time required for intubation.

Comparison of the force applied on oral structures during intubation attempts by novice physicians between the Macintosh direct laryngoscope, Airway Scope and C-MAC PM: a high-fidelity simulator-based study

OBJECTIVE

We examined whether the use of Airway Scope (AWS) and C-MAC PM (C-MAC) decreased the force applied on oral structures during intubation attempts as compared with the force applied with the use of Macintosh direct laryngoscope (DL).

DESIGN

Prospective cross-over study.

PARTICIPANTS

A total of 35 novice physicians participated.

INTERVENTIONS

We used 6 simulation scenarios based on the difficulty of intubation and intubation devices.

OUTCOME MEASURES

Our primary outcome measures were the maximum force applied on the maxillary incisors and tongue during intubation attempts, measured by a high-fidelity simulator.

RESULTS

The maximum force applied on maxillary incisors was higher with the use of the C-MAC than with the DL and AWS in the normal airway scenario (DL, 26 Newton (N); AWS, 18 N; C-MAC, 52 N; p<0.01) and the difficult airway scenario (DL, 42 N; AWS, 24 N; C-MAC, 68 N; p<0.01). In contrast, the maximum force applied on the tongue was higher with the use of the DL than with the AWS and C-MAC in both airway scenarios (DL, 16 N; AWS, 1 N; C-MAC, 7 N; p<0.01 in the normal airway scenario; DL, 12 N; AWS, 4 N; C-MAC, 7 N; p<0.01 in the difficult airway scenario).

CONCLUSIONS

The use of C-MAC, compared with the DL and AWS, was associated with the higher maximum force applied on maxillary incisors during intubation attempts. In contrast, the use of video laryngoscopes was associated with the lower force applied on the tongue in both airway scenarios, compared with the DL. Our study was a simulation-based study, and further research on living patients would be warranted.

Double-lumen tube intubation using video laryngoscopy causes a milder cardiovascular response compared to classic direct laryngoscopy

Objective:

To determine whether there is a clinically relevant difference between the circulatory responses to double-lumen tube intubation (DLTI) with the GlideScope video laryngoscope versus the Macintosh direct laryngoscope.

Methods:

Eighty adult patients requiring double-lumen tubes for thoracic surgery were randomly and equally allocated to either a Macintosh direct laryngoscope group (DL group, n = 40) or a Glide Scope video laryngoscope group (GS group, n = 40). DLTI was performed after airway evaluations and induction of anesthesia. Systolic blood pressure (SBP) and heart rate (HR) were recorded before induction (baseline values), immediately before intubation (post-induction values), at intubation and after intubation. Rate-pressure-product (RPP), and the areas under SBP- and HR-time curves were calculated. All data obtained by the two devices were compared.

Results:

After laryngoscope insertion, SBP of DL and GS groups changed significantly differently (13.1% vs. 4.6%, P< 0.001), while HR changed similarly (17.2% vs. 14.6%, P = 0.074). One minute after intubation, both SBP and HR significantly increased in both groups (SBP: 11.6% vs. 11.9%; HR: 18.4% vs. 10.8%), but there were no significant differences between the two groups. RPP significantly increased in both groups after laryngoscope insertion (32.6%, P=0.001; 18.2%, P=0.002), and there was a significant difference between the two groups (P =0.001). Throughout intubation, the areas under SBP-time curves had a significant difference between the two groups (P = 0.042), while those under HR-time curves did not differ significantly (P=0.06).

Conclusion:

The intubation response was most significant upon laryngoscope insertion during the whole intubation process. The GlideScope video laryngoscope induced milder circulatory fluctuations than the Macintosh direct laryngoscope did, suggesting that DLTI using video laryngoscopy can help reduce the cardiovascular response to intubation.

Using Video-recorded Laryngoscopy to Evaluate Laryngoscopic Blade Approach and Adverse Events in Children

OBJECTIVES

Using recordings of endotracheal intubation attempts obtained with a video-enabled laryngoscope with Miller and Macintosh blades, the authors sought to evaluate the association between laryngoscopic approach (right-sided vs. midline) and intubation success, as well as adverse event rates in the pediatric emergency department (ED).

METHODS

This was a retrospective cohort study of children younger than 21 years who underwent endotracheal intubation with a C-MAC video laryngoscope in a tertiary care ED between August 2009 and May 2013. The primary outcome was successful endotracheal intubation on the first attempt. The secondary outcomes included time to intubation, video-recorded adverse events (oropharyngeal mucosal injury and aspiration), and physiologic adverse events. Multivariate regression models were used to determine the relationship between laryngoscope blade position and outcome measures adjusted for patient and provider factors.

RESULTS

The cohort consisted of complete video recordings for 105 of 143 (73%) patient encounters with intubations. The first-pass success rate did not significantly differ based on laryngoscopic approach (adjusted odds ratio [aOR] = 0.76, 95% confidence interval [CI] = 0.29 to 2.0). Among patients successfully intubated on the first attempt, the median time to intubation was longer for the right-sided approach compared to the midline approach (42 seconds vs. 31.5 seconds; p < 0.05). The odds of mucosal injury and aspiration were higher among patients intubated using a right-sided approach compared to a midline approach (aOR = 4.1, 95% CI = 1.2 to 14.5; aOR = 7.7, 95% CI = 1.5 to 39.5, respectively). Rates of physiologic adverse events did not differ based on approach.

CONCLUSIONS

First-pass success rate did not differ based upon laryngoscopic approach type; however, a right-sided approach was associated with a longer time to intubation, as well as higher rates of mucosal injury and aspiration among patients undergoing video-enabled intubation in a pediatric ED.

Assessment of competency during orotracheal intubation in medical simulation

BACKGROUND

Clinicians performing orotracheal intubation need to be competent to perform this technical skill safely. It is recognized that aggressive force applied during direct laryngoscopy may damage the oropharyngeal soft tissue; however, force is seldom considered in assessment of competency. The objective of this study was to explore the force applied during orotracheal intubation as a method of further discriminating between levels of competence. We sought evidence of construct validity in the form of discriminant, criterion, and concurrent validity. We hypothesized that the force generated during simulated intubation could serve to discriminate skill level among clinicians.

METHODS

A convenience sample of 35 health-care professionals filled a self-reported questionnaire and were then divided into the following three groups: Group 1, experts (n=16); Group 2, intermediates (n=7); and Group 3, novices (n=12). They then intubated a part-task trainer (Laerdal Airway Management Trainer) after reviewing a procedural video and engaging in one practice session. Intubations were recorded. Outcome measures were as follows: (i) force applied to the epiglottis, calculated (in newtons) using two superimposed pressure-sensitive films (Prescale; Fujifilm, Madison, WI, USA) on the laryngoscope blade; (ii) number of attempts required to achieve successful intubation; (iii) time to intubation; and (iv) hand position.

RESULTS

Of the four outcome measures, only force applied during orotracheal intubation was able to discriminate between groups. All data are reported as the mean (sd). There was a significant difference in force between groups during orotracheal intubation [one-way anova; experts, 102 (25) N; intermediates, 134 (28) N; and novices, 153 (43) N], with a significant difference (P<0.05) noted between novice and experts on post hoc analysis.

CONCLUSIONS

Force exerted during intubation provides meaningful information when attempting to discriminate intubation skill level. Force demonstrated criterion validity and could be used as a measure of competency during training.

Body posture during simulated tracheal intubation: GlideScope(®) videolaryngoscopy vs Macintosh direct laryngoscopy for novices and experts

Tracheal intubation requires the anaesthetist to adopt an awkward body posture. To investigate how posture may be improved, we compared the effects of laryngoscopy technique (GlideScope(®) vs Macintosh blade) and experience (novices vs experts) on body posture angles and the Rapid Entire Body Assessment postural analysis score. Novices (25 medical students) and experts (26 anaesthetists) were video-recorded performing intubation in a manikin using both devices. The GlideScope resulted in smaller deflections for all analysed posture angles (all p values < 0.001) except the wrist compared with the Macintosh blade. Novices showed more trunk (p < 0.001) and neck (p = 0.002) flexion than experts. Using the GlideScope resulted in a lower Rapid Entire Body Assessment score compared with using the Macintosh blade (p < 0.001), indicating that the GlideScope resulted in body posture less likely to induce musculoskeletal injuries. From an ergonomic point of view, the GlideScope should be the preferred technique for laryngoscopy.

Postoperative sore throat after laryngoscopy with macintosh or glide scope video laryngoscope blade in normal airway patients

Background:

The Glide Scope videolaryngoscope provides a suitable view for intubation, with less force required.

Objectives:

The present study was conducted, to compare postoperative sore throat and hoarseness after laryngoscopy and intubation, by Macintosh blade or Glide Scope video laryngoscope in normal airway patients.

Patients and Methods:

Three hundred patients were randomly allocated into two groups of 150: Macintosh blade laryngoscope or Glide Scope video laryngoscope. The patients were evaluated for 48 hours for sore throat and hoarseness by an interview.

Results:

The incidence and severity of sore throat in the Glide Scope group, at 6, 24 and 48 hours after the operation, were significantly lower than in the Macintosh laryngoscope group. In addition, the incidence of hoarseness in the Glide Scope group, at 6 and 24 hours after the operation, were significantly lower than in the Macintosh laryngoscope group. The incidence and severity of sore throat in men, at 6 and 24 hours after the operation, were significantly lower than in the women.

Conclusions:

The incidence and severity of sore throat and hoarseness after tracheal intubation by Glide Scope were lower than in the Macintosh laryngoscope. The incidence and severity of sore throat were increased by intubation and longer operation times.

Comparison of heart rate variability response in children undergoing elective endotracheal intubation with and without neuromuscular blockade: a randomized controlled trial

BACKGROUND

The routine use of neuromuscular blocking drugs (NMBD) for endotracheal intubation in children is the subject of much controversy. The analysis of heart rate variability (HRV) can reveal information about the functional state of the autonomic nervous system (ANS).

AIM

The purpose of this study was to determine if HRV elucidates differences in the sympathovagal balance of children undergoing elective endo-tracheal intubation with and without neuromuscular blockade (NMB).

METHODS

In this prospective study, 38 children (2-6 years) scheduled for adenotonsillectomy were randomized into two groups to receive fentanyl 2 μg·kg(-1) and propofol 4 mg·kg(-1) , with either mivacurium 0.25 mg·kg(-1) (NMB group) or saline solution (NoNMB group) for anesthesia induction. The same experienced, blinded anesthesiologist performed endotracheal intubation. Heart rate variability, RR intervals, ECG as well as an electroencephalogram were recorded with HRV and BIS XP monitors, respectively. Heart rate variability was analyzed in the frequency domain.

RESULTS

There was no significant difference in HRV changes immediately after mivacurium administration compared with an administration of saline. The groups were comparable for the bispectral index value (NMB 35 [33-41] vs NoNMB 34 [32-42]) during endotracheal intubation. Changes in both the low-frequency power and the low-/high-frequency ratio immediately after endotracheal intubation compared with the unstimulated state before laryngoscopy were significantly higher without NMB (P = 0.015 and P = 0.006, respectively), whereas there was no significant difference with respect to the high-frequency power.

CONCLUSIONS

The stress response during endotracheal intubation in pediatric patients represented by the frequency domain analysis of HRV was found to be higher without NMB. When mivacurium was added to a propofol-fentanyl induction regimen, the ANS alterations during endotracheal intubation decreased significantly.

Upper limb muscular activity and perceived workload during laryngoscopy: comparison of Glidescope(R) and Macintosh laryngoscopy in manikin: an observational study

BACKGROUND

The interaction between operators and their working environment during laryngoscopy is poorly understood. Numerous studies have focused on the forces applied to the patient's airway during laryngoscopy, but only a few authors have addressed operator muscle activity and workload. We tested whether different devices (Glidescope(®) and Macintosh) use different muscles and how these differences affect the perceived workload.

METHODS

Ten staff anaesthetists performed three intubations with each device on a manikin. Surface electromyography was recorded for eight single muscles of the left upper limb. The NASA Task Load Index (TLX) was administered after each experimental session to evaluate perceived workload.

RESULTS

A consistent reduction in muscular activation occurred with Glidescope(®) compared with Macintosh for all muscles tested (mean effect size d=3.28), and significant differences for the upper trapezius (P=0.002), anterior deltoid (P=0.001), posterior deltoid (P=0.000), and brachioradialis (P=0.001) were observed. The overall NASA-TLX workload score was significantly lower for Glidescope(®) than for Macintosh (P=0.006), and the factors of physical demand (P=0.008) and effort (P=0.006) decreased significantly.

CONCLUSIONS

Greater muscular activity and workload were observed with the Macintosh laryngoscope. Augmented vision and related postural adjustments related to using the Glidescope(®) may reduce activation of the operator's muscles and task workload.

[Video laryngoscopy olé! Time to say good bye to direct and flexible intubation?]

A number of video laryngoscopy systems have been introduced into anesthetic practice in recent years. Due to the technical concepts of these systems exposure of the laryngeal structures is usually better than with direct laryngoscopy, both in normal airways as well as in those that are difficult to manage. With the increasing use of video laryngoscopy it seems as if direct laryngoscopy and flexible fibrescopic intubation are at risk of becoming redundant. This article describes current developments and discusses why expertise in direct laryngoscopy and flexible fibrescopic intubation should be maintained, particularly by experts in airway management.

Nasotracheal intubation with three indirect laryngoscopes assisted by standard or modified Magill forceps

We assessed the effect of modifying standard Magill forceps on the laryngeal introduction of an Eschmann stylet during nasotracheal intubations with three indirect laryngoscopes (Airtraq™, C-MAC(®) or GlideScope(®)) in patients with predicted difficult intubation. We allocated 50 participants to each laryngoscope. The stylet was advanced by one forceps followed by the other (standard or modified), with each sequence allocated to 25/50 for each laryngoscope. There were no differences in rates of failed tracheal intubation with the allocated laryngoscopes: 6/50, 5/50 and 5/50, respectively. An Eschmann stylet was advanced into the trachea less often with the standard forceps (65% vs 93%, p < 0.0001). Mean (SD) time for stylet advancement was longer with the standard forceps, 38 (30) vs 19 (19) s, p < 0.0001. In conclusion, the modified Magill forceps facilitated nasotracheal intubation, independent of the type of indirect laryngoscope.

Training in trauma management: the role of simulation-based medical education

Simulation-based medical education (SBME) offers a safe and "mistake-forgiving" environment to teach and train medical professionals. The diverse range of medical-simulation modalities enables trainees to acquire and practice an array of tasks and skills. SBME offers the field of trauma training multiple opportunities to enhance the effectiveness of the education provided in this challenging domain. Further research is needed to better learn the role of simulation-based learning in trauma management and education.

[Indirect laryngoscopy/video laryngoscopy. A review of devices used in emergency and intensive care medicine in Germany]

Airway management in intensive care or emergency medicine is particularly challenging and is often associated with life-threatening complications. An innovation in the field of airway management is the use of indirect laryngoscopy by means of video laryngoscopes. A digital camera or an optical system at the tip of a laryngoscope blade enables an indirect "look around the corner" to the glottis. Studies have shown that the advantages of video laryngoscopes for endotracheal intubation are particularly beneficial in difficult airway situations. However, the successful use in challenging intubations requires experience and regular use in daily practice. This review gives an overview of indirect laryngoscopes commonly used in Germany and also presents new study results for these novel devices.