Stress response to tracheal intubation: direct laryngoscopy compared with blind oral intubation

Haemodynamic and hormonal responses to tracheal intubation can be profound and associated with serious cardiovascular and cerebral side effects. The Augustine Guide, a device enabling blind oral intubation, has been introduced recently. The aim of our study was to compare the haemodynamic and hormonal stress response of this method with direct laryngoscopy. Thirty five patients (ASA 1 and 2) were randomly assigned to undergo either direct laryngoscopy (n = 17), or blind oral intubation (n = 18). Haemodynamic responses and concentrations of adrenaline, noradrenaline and prolactin were determined prior to induction, before intubation and 5 min after intubation. The median duration of intubation was 22s for direct laryngoscopy vs 46s for blind oral intubation (p < 0.05). Between the groups, no significant differences were observed for heart rate, systolic or mean arterial blood pressure. Serum levels of adrenaline decreased slightly after induction and remained unaltered after intubation in both groups. Noradrenaline (1.01 vs 0.66 nmol.l-1) and prolactin (5.2 vs 2.9 nmol.l-1) levels were significantly higher after direct laryngoscopy compared to blind oral intubation. Although blind oral intubation took significantly longer to perform than direct laryngoscopy, hormonal stress response was less pronounced. Blind oral intubation should therefore not be withheld from patients with impaired cardiovascular reserve.