Factors predicting atracurium reversal time

Determination of dose and efficacy of atracurium for rapid sequence induction of anesthesia: A randomised prospective study

Background and Aims:

Succinylcholine and high dose rocuronium are neuromuscular blocking agents commonly used for rapid sequence induction of anesthesia. Their usage is limited or contraindicated in some circumstances. The aim of this study is to determine the dosage and efficacy of atracurium without priming for rapid sequence induction of anesthesia.

Material and Methods:

One hundred fifteen surgical patients under general anesthesia were randomised into three groups. All patients were given 2-3 mg/kg propofol and 1 μg/kg fentanyl intravenously for the induction of anesthesia followed by different doses of atracurium (0.6 mg/kg, 0.75 mg/kg or 1 mg/kg) without a priming dose. Tracheal intubation was performed within one minute after the administration of the study drugs. The intubating conditions, vocal cord movement and diaphragm movement were graded as the primary endpoints. Statistical analysis was done using one-way analysis of variance (ANOVA) and Post Hoc tests.

Results:

Atracurium doses of 1 mg/kg, 0.75 mg/kg, and 0.6 mg/kg provided 51.4%, 43.6% and 26.3% success rates of intubation without coughing or bucking, respectively (P = 0.03). The intubating conditions were graded as excellent or good in 86.5% of the 1 mg/kg atracurium group patients and in 84.6% of the 0.75 mg/kg group patients (P < 0.05). An atracurium dose of 1 mg/kg facilitated significant differences in vocal cord and diaphragm paralysis compared with the dose of 0.6 mg/kg (P = 0.03).

Conclusion:

The administration of a relatively high dose of atracurium without priming can be used as an alternative neuromuscular blocking agent for rapid sequence induction of anesthesia in some circumstances.

Dose-reversal effect relationship of three different doses of neostigmine in obese patients: A randomised clinical trial

Background and Aims:

Previous studies suggest that administration of vecuronium based on total body weight rather than ideal body weight (IBW) in obesity results in overdosing with prolonged recovery times. We hypothesised that larger doses of neostigmine could result in faster recovery in obese patients administered vecuronium based on total body weight.

Methods:

Forty-five obese American Society of Anesthesiologists' II patients undergoing elective surgery under general anaesthesia were randomised into 3 groups to receive neostigmine 30, 40 and 50 μg/kg. Following induction, patients were paralysed with vecuronium 0.1 mg/kg based on total body weight. Reversal was achieved with neostigmine based on the patient's group, and time to train-of-four (TOF) ratios of 0.5, 0.7 and 0.9 measured. The primary outcome variable was time to achieve TOF ratio >0.9.

Results:

Neostigmine 50 μg/kg achieved faster recovery to TOF 0.7 than neostigmine 30 and 40 μg/kg. There was no significant difference in recovery times to TOF 0.7 in patients receiving either 30 or 40 μg/kg of neostigmine. However, neostigmine 40 μg/kg attained TOF ratio 0.9 faster than 30 μg/kg. We did not note a significant difference between the 40 and 50 μg/kg dose with regard to recovery of TOF to 0.9.

Conclusion:

Facilitated recovery from neuromuscular blockade to TOF of 0.7 was faster with neostigmine 50 μg/kg compared to 40 or 30 μg/kg. Recovery to TOF ratio of 0.9 was not significantly different with 40 or 50 μg/kg doses although such time was faster as compared to 30 μg/kg dose.

Development and potential clinical impairment of ultra-short-acting neuromuscular blocking agents

Developing a non-depolarizing neuromuscular blocking agent that, like succinylcholine, has a rapid onset and a short duration of effect remains a goal of ongoing research. While rocuronium fills a portion of this need, the large doses required for rapid intubation render it a much longer-acting neuromuscular blocking agent. Postoperative residual neuromuscular block (NMB) is an increasingly recognized complication of non-depolarizing neuromuscular blocking agents. This occurs because of dosing choices for neuromuscular blocking agents and anticholinesterases as well as insensitivity of typically used monitors of depth of NMB. While antagonism of NMB is necessary with partial recovery, it is unnecessary with more complete recovery. Even when monitoring with an accelerograph, reversal of NMB is complicated. In addition to the pharmacodynamics of the individual neuromuscular blocking agents, factors such as timing of anticholinesterase administration, dose of anticholinesterase, concomitant medications, electrolyte abnormalities, and hepatic or renal disease can influence the degree of reversal. Sugammadex works differently than anticholinesterases and, when administered in appropriate doses, can reverse even profound block induced with vecuronium or rocuronium. Two new fumarate neuromuscular blocking agents have a rapid onset of effect and can be reversed at any time by administration of cysteine, which could significantly reduce the risk of postoperative residual NMB.

Reversal of vecuronium with neostigmine: a comparison between male and female patients

We investigated the differences between males and females in the reversal effect of neostigmine on neuromuscular blockade. Thirty male and 30 female patients undergoing elective general anesthesia were studied. Vecuronium was given in all patients anesthetized with nitrous oxide, oxygen, and sevoflurane. After the surgical procedure, when T1 (1st response in train-of-four (TOF))/control returned to 0.25, neostigmine 40 microg/kg in combination with atropine 20 microg/kg was given to antagonize residual neuromuscular blockade. Three, six, nine, 12, and 15 minutes after neostigmine reversal, T1/control or TOF ratio (T4/T1) did not significantly differ between the sexes. Also, 15 minutes after neostigmine administration, the number of patients in whom recovery from neuromuscular blockade was sufficient to guarantee good respiratory function, i.e., TOF ratio > 0.74, did not significantly differ between the sexes. In contrast, 15 minutes after neostigmine, the number of patients in whom recovery from neuromuscular blockade was adequate to ensure satisfactory recovery from neuromuscular blockade including the return of the faculty of sight, i.e., TOF ratio > 0.9, was significantly less in the males than in females (6 vs. 14, P = 0.028). In conclusion, 15 min after neostigmine, TOF ratio less often returns to a value of more than 0.9 in males than in females.

Retracted : Reversal of vecuronium with neostigmine in patients with diabetes mellitus

Reversal of vecuronium-induced neuromuscular blockade with neostigmine was compared in two groups of 16 subjects: patients with Type 2 diabetes mellitus and normal controls. When the first twitch of the train-of-four had returned to 25% of the control value, neostigmine 40 microg x kg(-1) and atropine 20 microg x kg(-1) were given to reverse the neuromuscular blockade. The train-of-four ratio was lower at 3 min, 6 min, 9 min, 12 min and 15 min after reversal in the diabetic group than in the control group but the differences did not reach statistical significance. Fifteen minutes after reversal, the number of patients in whom recovery from neuromuscular blockade was judged insufficient to guarantee good respiratory function (train-of-four ratio < 0.74) did not differ between the groups. However, 15 min after reversal, the number of patients with a train-of-four ratio < 0.9 was significantly higher in the Diabetic Group than in the Control Group (15 vs. 10, p = 0.033).