Onset of vecuronium neuromuscular block is more rapid in patients undergoing Caesarean section

Abstract

This investigation was carried out in ten patients undergoing elective Caesarean section and the results were compared with those of a control group of ten nonpregnant females of the same age group. The study investigated the onset of vecuronium neuromuscular block and the conditions of tracheal intubation when ketamine (1.5 mg.kg-1)-vecuronium 100 micrograms.kg-1) sequence was used for rapid-sequence induction of anaesthesia. The ulnar nerve was stimulated supra-maximally at the wrist with train-of-four stimuli every 20 sec, and the electromyographic response of the adductor pollicis muscle was displayed. The onset of 50% neuromuscular block as monitored by electromyography was shorter in the Caesarean group (80 +/- 30 sec) than in the control group (144 +/- 43 sec). The conditions of intubation at 50% block were adequate in both groups. Also, the onset of 90% block was shorter in the Caesarean group. The time of recovery to T1/control ratio of 25% was longer in the Caesarean group (46 +/- 10 min) than in the control patients (28 +/- 10 min). The results show that administration of vecuronium according to body weight results in a more rapid onset and delayed recovery of neuromuscular block in pregnant women undergoing Caesarean section than in the nonpregnant control patients.

Surgeon-controlled mivacurium administration during elective Caesarean section

“…In contrast to mivacurium, the clinical duration of vecuronium-induced block is prolonged and the requirements are reduced in the pregnant and postpartum patient. 24,25 In conclusion, we have demonstrated that maintenance of mivacurium-induced neuromuscular block during elective Caesarean section could be achieved with the use of an on-demand SCR technique guided by the direct assessment of abdominal muscle tone. Compared with a continuous infusion given by the attending anaesthetist to maintain 95-100% at the hand muscles, the SCR technique was associated with reduced mivacurium requirement, a substantial degree of neuromuscular recovery at the end of surgery, a shorter time to adequate recovery, and a reduced need for neostigmine antagonism.…”

Anesthesia in pregnant patients for nonobstetric surgery

“…Prolonged neuromuscular blockade with succinylcholine is uncommon, however, as the increased volume of distribution offsets the impact of decreased drug hydrolysis [24]. Vecuronium at a standard dose of 0.2 mg/kg has been shown to have a faster onset time and longer duration of action in pregnancy [25]. The onset time of rocuronium at a dose of 0.6 mg/kg is unchanged but also demonstrates a longer duration of action compared with nonpregnant patients [26].…”

Current anesthesıa for Cesarean Sectıon

“…Ketamine has been shown to improve intubating conditions when used in association with rocuronium [11]. Ketamine can be safely used for the induction of general anesthesia in patients undergoing cesarean section with possible hypovolemia or with acute asthma [12,13]. The drug produces minimal respiratory depression and usually increases arterial blood pressure by 10 to 25 percent.…”

“…Using ketamine for induction of general anesthesia in parturients who were undergoing cesarean section not only facilitates tracheal intubation at 50% NMB but, may allow the administration of 100% oxygen without anesthetic supplementation until delivery of the newborn [13]. However, because of the sympathomimetic effects of ketamine, it is contraindicated in hypertensive and preeclamptic parturients.…”