Muscle Relaxants
Pancuronium bromide frequently has been used for muscle relaxation
during high-dose opioid anesthesia. It was reported that the vagolytic action of
pancuronium can attenuate opioid-induced bradycardia and support blood pressure,
[548]
but other reports cautioned the use of pancuronium
with high-dose opioids.[549]
[550]
[551]
Many factors may alter the impact of pancuronium
and other muscle relaxants on hemodynamics when they are combined with opioids:
for example, the dose, timing, and rate of administration of each relaxant, as well
as the premedication, intravascular volume, left ventricular function, and presence
of other drugs with autonomic nervous system actions.[548]
Combinations of vecuronium and high doses of opioids produce negative
chronotropic and inotropic effects resulting in decreases in heart rate, cardiac
output, and blood pressure and increases in the need for vasopressor support.[552]
[553]
Compared with vecuronium (0.15 mg/kg), pancuronium
(0.15 mg/kg) produced tachycardia more often (32% versus 7%) in patients undergoing
coronary artery surgery.[554]
However, pancuronium-induced
tachycardia was easily and rapidly treated and caused no differences in ischemia
or perioperative myocardial infarction. It was also reported that there is no significant
difference in the frequency of intraoperative ischemic events with pancuronium compared
with vecuronium.[555]
Metocurine (0.5 mg/kg) alone produces less hemodynamic fluctuation
than pancuronium during opioid anesthesia, although high doses (>0.3 mg/kg) may
cause hypotension. Doxacurium causes no circulatory changes during sufentanil-midazolam
anesthesia.[556]
Pipecuronium, in doses as high
as three times the ED95
, has also been found to be devoid of circulatory
actions in patients undergoing coronary artery bypass grafting surgery under midazolam-fentanyl
anesthesia.[557]
Mivacurium chloride produces modest
decreases in blood pressure, probably due to histamine release when larger doses
(e.g., twice the ED95
) are injected rapidly (<30 seconds).[558]
[559]
Few significant circulatory changes were
associated
with mivacurium (0.15–0.25 mg/kg over 60 seconds) in patients undergoing coronary
artery bypass grafting surgery and receiving sufentanil-midazolam anesthesia.[560]
