To compare haemodynamic responses associated with equipotent doses of
neuromuscular blockers and high-dose
fentanyl (50 micrograms.kg-1), 40 patients with
aortic valve stenosis (AS) and 20 patients with aortic insufficiency (AI) were randomized to four study groups to receive the following: (1)
pancuronium 0.12 mg.kg-1, (2)
vecuronium 0.12 mg.kg-1, (3)
atracurium 0.4 mg.kg-1, or (4)
pancuronium-
metocurine mixture (0.4 mg + 1.6 mg/ml): 1 ml/10 kg).
Neuromuscular blockers were injected at the same time with the
fentanyl; haemodynamics were recorded with the patients awake (baseline), at two minutes post-induction, and at two and five minutes after intubation. In patients with AS,
pancuronium increased heart rate more than
vecuronium or
atracurium; heart rates were also higher with the
pancuronium-
metocurine mixture than with
vecuronium. Although there were no ECG signs of ischaemia, one patient given
pancuronium developed severe
hypotension associated with
tachycardia. Reductions in SVR after
atracurium allowed small but significant (p less than 0.01) decreases in MAP which were well tolerated; one patient, however, did develop severe
hypotension. Intubation resulted in significant (p less than 0.01) increases in MAP in the
pancuronium-
metocurine mixture group.
Vecuronium permitted the most stable overall haemodynamic course at all measurement times. In contrast, patients with AI showed stable haemodynamics after
vecuronium,
pancuronium and the
pancuronium-
metocurine mixture; one patient became tachycardic following
vecuronium.
Atracurium caused unexplained elevations in diastolic and mean arterial pressures which were significant when compared to
vecuronium (p less than 0.01). These results in increases in PCWP; mean PA pressures and CVP were also increased. These effects of
atracurium inpatients with Al need further evaluation.