The Pentax airway scope versus the Macintosh laryngoscope: Comparison of hemodynamic responses and concentrations of plasma norepinephrine to tracheal intubation

Abstract

Background: The Pentax Airway Scope (AWS) is a video laryngoscope designed to facilitate tracheal intubation with a high-resolution image. The Pentax AWS has been reported to cause less hemodynamic stress than the Macintosh laryngoscope. The aims of this study are to investigate the differences in hemodynamic responses and norepinephrine concentrations to tracheal intubation between procedures using he Pentax AWS and the Macintosh laryngoscope.

Methods: Forty patients (American Society of Anesthesiologists class I-II, age range: 18-60 years) were randomly assigned to be intubated with either the Pentax AWS or the Macintosh laryngoscope while under general anesthesia. Routine monitoring, including invasive arterial blood pressure and bispectral index, were applied. Thiopental (4 mg/kg), fentanyl (1 µg/kg), midazolam (0.05 mg/kg), and rocuronium (0.6 mg/kg) were administered for anesthetic induction. Systolic, diastolic, and mean blood pressures and heart rates were recorded pre-intubation, immediately post-intubation (T0), and over the following 10 minutes at one minute intervals (T1, T2, T3, T4, T5…T10). Patient blood was sampled for norepinephrine concentrations pre-intubation (baseline) and post-intubation (T1). Evidence of sore throat was evaluated 30 min and 24 hr after extubation. Data were transformed to % basal and expressed as mean ± SD.

Results: The systolic, diastolic, and mean blood pressure, and heart rate at T0 and T4 were significantly different between the two groups. There was no significant difference in plasma norepinephrine between the two groups. The difference in incidence of sore throat was not significant between the two groups.

Conclusions: Pentax-AWS for tracheal intubation has greater hemodynamic stability than the Macintosh blade laryngoscope.

Keywords: Hemodynamic response; Norepinephrine; Pentax AWS; Sore throat.

Fig. 1

Hemodynamic responses to tracheal intubation. Data are presented as % basal: % basal = 100 × hemodynamic parameters at specific time/baseline hemodynamic parameters. The dotted line of the y intercept at 100 is the baseline value in each panel. Group P (●) = group receiving Pentax AWS (Airway Scope), Group M (○) = group receiving Macintosh laryngoscope, T0 = time after tracheal intubation 0 minutes, T1-T10 = time after tracheal intubation 1-10 minutes. SBP (A): systolic blood pressure, DBP (B): diastolic blood pressure, MBP (C): mean blood pressure, HR (D): heart rate. Statistical differences in hemodynamic responses to tracheal intubation between Group P and Group M were analyzed by repeated measures analysis of variance (rANOVA), followed by the Sidak multiple comparison test (^*P < 0.05).

Fig. 2

Concentration of plasma norepinephrine. Data are presented as % basal: % basal = 100 × concentration of post-intubation norepinephrine during at T1 (pg/ml)/concentration of pre-intubation norepinephrine (pg/ml). The dotted line of the y intercept at 100 is the baseline value. NE=norepinephrine, Group P (■) = group using Pentax AWS (Airway Scope), Group M (□) = group using Macintosh laryngoscope. Statistical differences in norepinephrine concentration between Group M and Group P were analyzed with an unpaired t-test. There is no significant difference between the two groups in post-intubation concentrations (P > 0.05).