Improvement in Cormack and Lehane grading with laparoscopic assistance during tracheal intubation

A randomised comparative study of "videoendoscope" with the Truview EVO2, C-MAC D blade videolaryngoscope and the Macintosh laryngoscope

Background and Aims

Videolaryngoscopes are crucial components of a difficult airway cart. Issues of cost and availability, however, remain a problem. We compared the combination of an endoscope used in conjunction with the Macintosh laryngoscope with established videolaryngoscopes and the Macintosh laryngoscope using the intubation difficulty scale (IDS) score.

Materials and Methods

A prospective randomised study including 120 adult patients, American Society of Anaesthesiologists (ASA) physical status I-III, with an anticipated difficult airway scheduled for elective surgery were randomly allocated to one of four groups: Truview EVO2 (group 1), C-MAC D Blade (group 2), videoendoscope (group 3), or Macintosh laryngoscope (group 4). The IDS score was the primary outcome. Secondary outcomes included the Cormack-Lehane grade, time to tracheal intubation, haemodynamic responses, and adverse events.

Results

A significant proportion of patients in groups 2 and 3 had an IDS score of zero (73.3 and 70%, respectively). IDS scores were significantly lower in the C-MAC D blade and videoendoscope groups attributable to differences in parameters N4, N5 and N6 [C/L grades, lifting force and laryngeal pressure required] (P < 0.001). The C-MAC D blade and the Macintosh laryngoscope required less time for intubation as compared to the Truview EVO2 and videoendoscope. No differences were noted in post-intubation haemodynamic parameters and other adverse events.

Conclusion

The performance of videoendoscope was comparable to C-MAC D Blade and superior to Truview EVO2 and Macintosh laryngoscope with respect to the IDS score and may thereby provide an effective alternative to commercial videolaryngoscopes in low resource settings.

[Comparison of different stylets used for intubation with the C-MAC D-Blade® Videolaryngoscope: a randomized controlled study]

OBJECTIVE

The angle of the C-MAC D-Blade^® videolaryngoscope, which is used for difficult airway interventions, is not compatible with routinely used endotracheal tubes.

METHODS

A prospective randomized crossover study was performed comparing five intubation methods for use with standardized airways, including using different stylets or no stylet: Group HS, hockey-stick stylet; Group DS, D-blade type stylet; Group CS, CoPilot^® videolaryngoscope rigid stylet^®; Group GEB, gum elastic bougie; and Group NS, no stylet. A manikin was used to simulate difficult intubation with a Storz C-MAC D-Blade^® videolaryngoscope. The duration of each intubation stage was evaluated.

RESULTS

Participants in this study (33 anesthesiology residents and 20 anesthesiology experts) completed a total of 265 intubations. The number of attempts made using no stylet was significantly greater than those made for the other groups (p<0.05 for group NS- group GEB, group NS- group DS, group NS- group CS and group NS- group HS). The duration to pass the vocal cords significantly differed among all groups (p<0.001). The total intubation duration was shortest when using D-blade stylet, CoPilot stylet and hockey stick stylet. Although no difference was observed between stylet groups, a significant difference was found between each of these three and no stylet and gum elastic bougie (p<0.05 and p<0.001, respectively).

CONCLUSION

Use of the correct stylet leads to a more efficient use of the Storz C-MAC D-Blade^®. In our study, the use of the D-blade stylet, the CoPilot stylet and the hockey stick stylet provided quicker intubation, allowed easier passage of the vocal cords, and decreased the total intubation duration. To confirm the findings of our study, randomized controlled human studies are needed.

[Nondepolarizing muscle relaxant improves direct laryngoscopy view with no effect on face mask ventilation]

BACKGROUND

Difficult or impossible face mask ventilation complicated with difficult tracheal intubation during anesthesia induction occurs in 0.4% of adult anesthesia cases, possibly leading to life-threatening complications. Because of such catastrophes, muscle relaxants have been recommended to be administered after confirming adequate face mask ventilation without a solid scientific validation of this principal.

METHODS

In this observational study, the ease of ventilation and the scores of direct laryngoscopy views before and after administration of cisatracurium were assessed in ninety young healthy adults, without anesthetic risks and without foreseen difficult intubation and who were scheduled for general elective surgeries.

RESULTS

Before muscle relaxation, 43 patients (48%) were Cormack Grade I, while the remaining 47 patients (52%) were either Cormack Grade II (28 patients, 31%) or Cormack Grade II (19 patients, 21%). Following muscle relaxation with cisatracurium, the number of patients with Cormack Grade I significantly increased from 43 patients (48%) to 65 patients (72%) (p=0.0013). Only 1 patient out of 19 patients (5%) improved his Cormack grade from Grade III to Grade I while 16 out 19 patients (84%) improved their Cormack grade from Grade III to Grade II after the use of cisatracurium. The quality of face mask ventilation did not differ with and without muscle relaxants in all patients.

CONCLUSION

The use of cisatracurium in healthy young adults undergoing general elective surgeries with no anticipated difficult endotracheal intubation had no effect on the quality of face mask ventilation despite resulting in a quantifiable improvement in the laryngeal view.