Pancuronium Requirements during Hypothermic Cardiopulmonary Bypass in Man

Abstract

Eight patients were studied to determine the changes in pancuronium requirements during hypothermic cardiopulmonary bypass. They were anaesthetised with fentanyl as the principal agent, ventilated with oxygen and the neuromuscular junction was monitored using train-of-four stimulation. After a bolus dose of pancuronium an infusion was used to maintain the first twitch of the train-of-four at 5-15 per cent of control. Before bypass the mean pancuronium infusion rate was 0.52 (SD 0.16) JJ.glkglmin. There was a small, brief increase in requirement with the initiation of bypass to 0.62 (SD 0.38) JJ.glkglmin, which was folio wed by a decrease of more than 80 per cent during hypothermia to 0.08 (SD 0.03) JJ.glkglmin. Rewarming was associated with a rapid increase in requirement to 0.64 (SD 0.17) JJ.glkglmin, which decreased to 0.33 (SD 0.23) JJ.glkglmin when normothermia was re-established.

Recovery of Neuromuscular Function After Cardiac Surgery: Pancuronium Versus Rocuronium

“…Direct muscle stimulation of the orbicularis oculi muscle may have occurred, which would also result in a relative overdose. Third, alterations in the pharmacokinetic and pharmacodynamic properties of pancuronium, which are induced by CPB, can contribute to postoperative residual muscle weakness (12)(13)(14)(15)(16). Increased sensitivity of muscles to pancuronium has been shown to persist into the post-CPB period (17).…”

The pharmacokinetics of anesthetic drugs and adjuvants during cardiopulmonary bypass

“…As a general rule, hypothermia and CPB decrease the amount of muscle relaxant required ( Table 2). Thus, when muscle relaxants are administered as a bolus and a subsequent infusion, although plasma concentration may decline transiently on institution of bypass [metocurine, pancuronium ( 64, 65)], the concentration subsequently rises [alcuronium ( 66), d‐tubocurarine ( 67)] consistent with decreased clearance ( 66, 67). Hence, maintenance requirements are less.…”

“…Hence, maintenance requirements are less. However, muscle relaxation with pancuronium requires supplementation at onset of bypass and during rewarming ( 64, 65). In contrast, the pharmacokinetic profile of metocurine is little perturbed by CPB and so maintenance requirements, except perhaps at institution of bypass, are little affected ( 68).…”