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A comparative study of five different techniques to reduce left ventricular dysfunction during endotracheal intubation

1991; Wiley; Volume: 35; Issue: 7 Linguagem: Inglês

10.1111/j.1399-6576.1991.tb03358.x

1399-6576

G. Dahlgren, Göran Settergren, Gun Öhqvist, L.‐Å. Brodin,

Anesthesia and Sedative Agents

Thirty‐five non‐selected, consenting patients were studied during induction of anesthesia before coronary artery bypass grafting. Anesthesia was induced with diazepam, thiopentone and fentanyl, followed by pancuronium. Before induction, 200 MBq Tc 99 m – HSA was given i.v. and ejection fraction (EF) of the left ventricle was measured with a collimated single‐crystal probe. The patients were allocated to five groups (seven patients in each) treated with: Group A: nitroglycerin i.v. bolus 4 μg x kg ‐1 given 30–60 s before laryngoscopy; Group B: nitroglycerin i.v. in continuous infusion, 1 μg x kg ‐1 x min ‐1 started before induction; Group C: two‐stage topical anesthesia of the vallecula region and larynx with lidocain; Group D: a combination of nitroglycerin and topical anesthesia (as in Group B and C); and Group E: propranolol i.v. 0.01 mg x kg ‐1 given 5 min before intubation. All groups reacted in the same way during induction of anesthesia up to the point of laryngoscopy. End‐diastolic volume and systemic arterial pressure decreased while cardiac index remained unchanged and EF increased. During laryngoscopy and intubation, however, differences between the groups were evident. Nitroglycerin i.v. as a bolus effectively prevented a reduction in EF and an increase in left ventricular volume. In addition to these beneficial hemodynamic effects, there was a moderate increase in heart rate and a reduction of stroke index. Continuous infusion of nitroglycerin and propranolol i.v. had no effect, since EF fell and left ventricular volume increased. Patients receiving topical anesthesia demonstrated a blunted response to endotracheal intubation with a moderate decrease in EF and an unchanged (Group C) or slightly increased (Group D) left ventricular volume.