A good laryngeal view does not guarantee perfectly successful tracheal intubation

Influence of Curved Video Laryngoscope Blade Sizes and Patient Heights on Video Laryngoscopic Views: A Randomized Controlled Trial

This study aimed to compare the video laryngoscope views facilitated by curved blades 3 and 4 with an exploration of the relationship between these views and patient height. Conducted as a randomized controlled trial, this study enrolled adults scheduled for surgery under general anesthesia. Intubation procedures were recorded, and the percentage of glottic opening was measured before tube insertion. Multivariate analysis validated the impact of various factors, including blade size and patient height, on the percentage of glottic opening scores. A total of 192 patients were included. The median percentage of glottic opening scores for curved blades 3 and 4 were 100 and 83, respectively (p < 0.001). The unstandardized coefficient indicated a significant negative impact of blade 4 on the percentage of glottic opening scores (-13, p < 0.001). In the locally estimated scatterplot smoothing analysis, blade 3 exhibited a steady rise in glottic opening scores with increasing height, whereas blade 4 showed a peak followed by a decline around 185 cm. The unstandardized coefficient of height showed no significant association (0, p = 0.819). The study observed superior laryngoscopic views with blade 3 compared to blade 4. However, no significant association was found between laryngoscopic views and patient height.

Videolaryngoscopy as a primary intubation modality in obstetrics: A narrative review of current evidence

Pregnancy-related physiologic and anatomic changes affect oxygenation and airway management, and it is widely believed that airway difficulty may be more common in obstetric patients as a result. In addition, most obstetric intubations are performed under emergency conditions, and preoperative airway assessment poorly predicts airway management outcomes. These considerations necessitate special protocols for airway care in the obstetric population, and the evolution of the videolaryngoscope represents one of the most important milestones in recent decades. However, recommendations for the use of videolaryngoscopy in obstetrics remain unclear. A considerable body of evidence affirms that videolaryngoscopy improves laryngeal visualisation, increases first-attempt and overall intubation success rates, shortens intubation time, and facilitates team communication and education. In contrast, a significant number of studies have also reported conflicting results regarding comparative clinical outcomes and have highlighted other limitations regarding the adoption of videolaryngoscopy in routine obstetric care. Nevertheless, considering the peculiarities of obstetric intubation, the Macintosh-style videolaryngoscope can be suggested as the primary intubation device as it offers the benefits of both videolaryngoscopy and direct laryngoscopy. However, more rigorous evidence is needed to clarify the current blind spots and controversies regarding the role of videolaryngoscopy in obstetrics.

Preoperative airway ultrasound assessment in the sniffing position: a prospective observational study

BACKGROUND

Clinical airway screening tests intend to predict difficult airways, but none have a high predictive value. Recent systematic reviews correlate ultrasound with difficult laryngoscopy. This study aimed primarily to correlate ultrasound measurements of anatomical upper airway structures in the sniffing position with difficult direct laryngoscopy. The secondary aim was to observe gender-based differences.

METHODS

This prospective, cross-sectional, single-center observational study included 209 patients requiring general anesthesia for elective surgery. Preoperatively, we performed six clinical airway assessments and three ultrasound measurements, which were the Distance from Skin to the Hyoid Bone (DSHB), to the Epiglottis (DSE), and to the anterior commissure of the vocal cords (DSAC) in a sniffing position. Benumof's criteria for the "best view at the first attempt" for direct laryngoscopy assessed the difficulty of laryngoscopy.

RESULTS

The distance from skin to the epiglottis was the best predictor of direct difficult laryngoscopy (defined as Cormack-Lehane grade ≥ 2b) with a minimum thickness cut-off at 2.70 ± 0.19 cm (sensitivity 91.3%; specificity 96.9%). The skin to the hyoid bone distance cut-off was 1.41 ± 0.30 cm with moderate correlation (sensitivity 80.4%; specificity 60.1%). No correlation was found for the distance to the anterior commissure of the vocal cords. In women compared to men, the skin to the epiglottis distance was more sensitive (92.3% vs. 90.9%) and specific (98.8% vs. 95.2%).

CONCLUSIONS

DSE in the sniffing position is the most reliable parameter for preoperative airway ultrasound assessment in the Caucasian population, with higher sensitivity and specificity in women, and might be considered as an independent predictor for direct difficult laryngoscopy.

Comparison of McGrath, Pentax, and Macintosh laryngoscope in normal and cervical immobilized manikin by novices: a randomized crossover trial

BACKGROUND

The aim of this study was to compare tracheal intubation performance regarding the time to intubation, glottic view, difficulty, and dental click, by novices using McGrath videolaryngoscope (VL), Pentax Airway Scope (AWS) and Macintosh laryngoscope in normal and cervical immobilized manikin models.

METHODS

Thirty-five anesthesia nurses without previous intubation experience were recruited. Participants performed endotracheal intubation in a manikin model at two simulated neck positions (normal and fixed neck via cervical immobilization), using three different devices three times each. Performance parameters included intubation time, success rate of intubation, Cormack Lehane laryngoscope grading, dental click, and subjective difficulty score.

RESULTS

Intubation time and success rate during first attempt were not significantly different between the 3 groups in normal airway manikin. In the cervical immobilized manikin, the intubation time was shorter (p = 0.012), and the success rate with the first attempt was significantly higher (p < 0.001) when using McGrath VL and Pentax AWS compared with Macintosh laryngoscope. Both VLs showed less difficulty score (p < 0.001) and more Cormack Lehane grade I (p < 0.001) in both scenarios. The incidence of dental clicks was higher with Macintosh laryngoscope compared with McGrath VL in cervical immobilized airway (p < 0.001).

CONCLUSIONS

McGrath VL and Pentax AWS did not show clinically significant decrease in intubation time, however, they achieved higher first attempt success rate, easier intubation and better glottis view compared with Macintosh laryngoscope by novices in a cervical immobilized manikin model. McGrath VL may reduce the risk of dental injury compared with Macintosh laryngoscope in cervical immobilized scenario.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT03161730), May 22, 2017 https://clinicaltrials.gov/ct2/hom.

Randomized comparison of McGrath MAC videolaryngoscope, Pentax Airway Scope, and Macintosh direct laryngoscope for nasotracheal intubation in patients with manual in-line stabilization

BACKGROUND

The objective of this study was to determine the clinical usefulness of videolaryngoscopes (VLs) by comparing the time to intubation (TTI) and the ease of intubation of McGrath MAC VL (MVL), Pentax Airway Scope VL (PVL), and Macintosh direct laryngoscope (DL) during nasotracheal intubation using manual in-line stabilization to simulate difficult airways.

METHODS

One hundred and twenty patients were randomly assigned to the MVL group (n = 40), the PVL group (n = 40), and the DL group (n = 40). Nasotracheal intubation was performed using MVL, PVL, or DL, according to group assignments. The primary outcome was TTI and secondary outcomes were glottic view, ease of intubation, and bleeding.

RESULTS

The TTI was significantly shorter in the MVL group than in the DL group (45 sec vs 57 sec; difference in means: - 12; 95% confidence interval [CI], - 21 to - 3; P = 0.01). The percentage of glottic opening and Cormack Lehane grade were significantly superior in the MVL and the PVL groups compared with the DL group (both P < 0.001). The intubation difficulty scale and numeric rating scale regarding ease of intubation were also significantly lower in the MVL and PVL groups than in the DL group (all P < 0.007). The incidence of bleeding was significantly lower in the MVL group than in the DL group (3 vs 15, relative risk 0.2; 95% CI, 0.06 to 0.64; P = 0.001).

CONCLUSION

This study showed that both MVL and PVL provided better visualization of the glottis and easier intubation, with less additional manipulation than DL during nasotracheal intubation in simulated difficult airways. Additionally, use of the MVL significantly shortened the TTI compared with the DL.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT02647606); registered 6 January, 2016.

Comparison of endotracheal intubation time in neutral position between C-Mac® and Airtraq® laryngoscopes: A prospective randomised study

BACKGROUND AND AIMS

In the recent past, many novel devices such as AirTraq^® and C-MAC^® video laryngoscope (VL) have been introduced in an attempt to reduce anaesthetic morbidity and mortality associated with difficult intubation. In this study, we aimed to evaluate and compare C-MAC^® VL with a standard Macintosh blade and the AirTraq^® optical laryngoscope as a intubating devices with the patient's head in neutral position.

METHODS

Sixty American Society of Anesthesiologist Physical Status I-II patients were randomly assigned to be intubated with C-MAC^® VL (Group CM; n = 30) or AirTraq^® (Group AT; n = 30) in the neutral position, with or without the application of optimization manoeuvres. The primary outcomes of this study were the success rate and the time taken to intubate. Glottic view, ease of tracheal intubation and haemodynamic responses were considered as secondary end points.

RESULTS

The incidence of successful intubation was similar in both the groups (P = 1.00). However, the time for intubation was significantly less with C-MAC^® VL (Group CM = 14.9 ± 12.89 s, Group AT = 26.3 ± 13.34 s; P = 0.0014). There was no significant difference between the two groups in terms of ease of intubation and glottic view. However, the haemodynamic perturbations were much less with C-MAC^® VL.

CONCLUSION

We conclude that both the devices were similar in visualising larynx in the neutral position with similar success rates of intubation. However, the C-MAC^® VL was better with respect to intubation time and haemodynamic stability.