Intubating conditions and blockade after mivacurium, rocuronium and their combination in young and elderly adults

Onset time, duration of action, and intubating conditions after mivacurium in elderly and younger patients

BACKGROUND

The neuromuscular blocking agent mivacurium can be used during anesthesia to facilitate tracheal intubation. Data on onset time, duration of action, and effect on intubating conditions in patients 80 years and older are however limited. We hypothesized that onset time and duration of action of mivacurium would be longer in elderly patients than in younger adults.

METHODS

This prospective observational study included 35 elderly (≥80 years) and 35 younger (18-40 years) patients. Induction of anesthesia comprised fentanyl 1-3 μg kg-1 and propofol 1.5-2.5 mg kg-1 and propofol and remifentanil for maintenance. Acceleromyography was used for monitoring neuromuscular blockade. The primary outcome was onset time defined as time from injection of mivacurium 0.2 mg kg-1 to a train-of-four (TOF) count of zero. Other outcomes included duration of action (time to TOF ratio ≥0.9), intubating conditions using the Fuchs-Buder scale and the intubating difficulty scale (IDS), and occurrence of hoarseness and sore throat postoperatively.

RESULTS

No difference was found in onset time comparing elderly with younger patients; 219 s (SD 45) versus 203 s (SD 74) (difference: 16 s (95% CI: -45 to 14), p = .30). Duration of action was significantly longer in elderly patients compared with younger patients; 52 min (SD 17) versus 30 min (SD 8) (difference: 22 min [95% CI: 15 to 28], p < .001). No difference was found in the proportion of excellent intubating conditions (Fuchs-Buder); 31/35 (89%) versus 26/35 (74%) (p = .12) or IDS score (p = .13). A larger proportion of younger patients reported sore throat 24 h postoperatively; 34% versus 0%, p = .0002. No difference was found in hoarseness.

CONCLUSION

No difference in onset time of mivacurium 0.2 mg kg-1 was found comparing elderly and younger patients. However, elderly patients had significantly longer duration of action. No difference was found in intubating conditions.

Onset time and duration of action of rocuronium 0.6 mg/kg in patients above 80 years of age: A comparison with young adults

BACKGROUND

The number of elderly is increasing, and a large proportion of these people will require surgery and anaesthesia. However, little data exist regarding rocuronium in patients above 80 years of age. The aim of this study was to determine the onset time and duration of action for rocuronium 0.6 mg/kg in patients above 80 years compared with young adults.

METHODS

This prospective observational study included 16 young (18-40 years) and 16 elderly (>80 years) patients scheduled for total intravenous anaesthesia. Neuromuscular block following rocuronium 0.6 mg/kg was monitored with acceleromyography using train-of-four (TOF) stimulation. The primary outcome was onset time (from administration of rocuronium until TOF count = 0). Secondary outcomes were duration of action (from administration to TOF ratio >0.9) and intubating conditions according to Intubation Difficulty Score.

RESULTS

Elderly patients, median age of 84 years, had significantly prolonged onset time compared to younger patients; median 135 seconds (135-158) vs 90 seconds (90-105), respectively, a mean difference of 82 seconds (40-124) and Wilcoxon Mann-Whitney odds (WMW) of 19.48 (7.48-X). Duration of action in elderly patients was significantly longer, with a median time of 81 minute (71-97) vs 53 minute (42-73), respectively, a mean difference of 31 minute (14-48), and WMW odds of 6.35 (2.59-X). There was no significant difference in intubating conditions.

CONCLUSIONS

Patients above 80 years had significantly prolonged onset time and duration of action after rocuronium 0.6 mg/kg compared with patients aged 18-40 years.

Duration of the action of rocuronium in patients with BMI of less than 25: An observational study

BACKGROUND

The duration of rocuronium in patients with BMI more than 30 kg m is prolonged. Whether the reverse is true when BMI is less than 18.5 kg m is unclear.

OBJECTIVE

The objective of this study was to investigate whether a BMI less than 25 kg m affects the duration of rocuronium in doses adjusted for actual body weight.

DESIGN

A prospective, observational, single-centre study.

SETTING

The operating room of a teaching hospital from 1 June 2008 to 30 June 2015.

PATIENTS

Thirty patients with American Society of Anesthesiologists physical status I or II who were scheduled to undergo elective surgery (BMI < 25 kg m, aged 23 to 74 years) maintained by 0.7 minimum alveolar concentration sevoflurane and remifentanil.

MAIN OUTCOME MEASURES

Repetitive train-of-four stimulation was applied and contractions of the adductor pollicis muscle were recorded. Duration of the initial dose of rocuronium (D1) was defined as the time from injection of rocuronium 0.6 mg kg to return of first twitch height to 25% of the control. Duration of additional doses (D2) was the time from a supplement of 0.15 mg kg rocuronium to return of first twitch height to 25% of the control. The relationship between D1 or D2 and BMI was examined using linear regression analysis.

RESULTS

Linear regression analysis revealed a significant correlation between duration of initial dose and BMI (R = 0.246; P = 0.00531). A significant correlation between the duration of the additional dose and BMI was also found (R = 0.316; P = 0.00122).

CONCLUSION

The lower the BMI, the shorter the duration of rocuronium at initial and additional doses determined by the actual body weight in adult patients with a BMI less than 25 kg m.

TRIAL REGISTRATION

www.umin.ac.jp/ctr/index/htm with registry number UMIN 00009337 and UMIN 000015407.

Pharmacological interventions for acceleration of the onset time of rocuronium: a meta-analysis

BACKGROUND

Rocuronium is an acceptable alternative when succinylcholine is contraindicated for facilitating the endotracheal intubation. However, the onset time of rocuronium for good intubation condition is still slower than that condition of succinylcholine. This study systematically investigated the most efficacious pharmacological interventions for accelerating the onset time of rocuronium.

METHODS

Medline, Embase, Cochrane Library databases, www.clinicaltrials.gov, and hand searching from the reference lists of identified papers were searched for randomized controlled trials comparing drug interventions with placebo or another drug to shorten the onset time of rocuronium. Statistical analyses were performed using RevMan5.2 and ADDIS 1.16.5 softwares. Mean differences (MDs) with their 95% confidence intervals (95% CIs) were used to analyze the effects of drug interventions on the onset time of rocuronium.

RESULTS

43 randomized controlled trials with 2,465 patients were analyzed. The average onset time of rocuronium was 102.4±24.9 s. Priming with rocuronium [Mean difference (MD) -21.0 s, 95% confidence interval (95% CI) (-27.6 to -14.3 s)], pretreatment with ephedrine [-22.3 s (-29.1 to -15.5 s)], pretreatment with magnesium sulphate [-28.2 s (-50.9 to -5.6 s)] were all effective in reducing the onset time of rocuronium. Statistical testing of indirect comparisons showed that rocuronium priming, pretreatment with ephedrine, and pretreatment with magnesium sulphate had the similar efficacy.

CONCLUSION

Rocuronium priming, pretreatment with ephedrine, and pretreatment with magnesium sulphate were all effective in accelerating the onset time of rocuronium, and furthermore their efficacies were similar. Considering the convenience and efficacy, priming with rocuronium is recommended for accelerating the onset time of rocuronium. However, more strict clinical trials are still needed to reach a more solid conclusion due to the large heterogeneities exist among different studies.

In non-obese patients, duration of action of rocuronium is directly correlated with body mass index

BACKGROUND

Administration of neuromuscular blocking agents using a dose calculated on actual body weight carries a risk of prolonged duration of action in obese patients whose body mass index (BMI) is > 30 kg · m(-2). In the present study, we hypothesized that there could be a correlation between BMI and the duration of action of rocuronium administered according to actual body weight in non-obese patients, in particular, overweight (BMI 25-30 kg · m(-2)) and underweight patients (BMI < 18.5 kg · m(-2)).

METHODS

Sixteen female patients (BMI 15-30 kg · m(-2), aged 45-60 yr) scheduled for elective surgery under total intravenous anesthesia were included in this study. Rocuronium 0.9 mg · kg(-1) was administered, and adductor pollicis train-of-four responses following ulnar nerve stimulation were monitored every minute with acceleromyography. The times from the injection of rocuronium until spontaneous recovery of first twitch to 5% (5% Duration) and 25% (25% Duration) of baseline were measured, and the correlation with BMI was analyzed.

RESULTS

A significant correlation between 5% Duration and BMI (r(2) = 0.56; P < 0.001) was found by linear regression analysis. A significant correlation was also found between 25% Duration and BMI (r(2) = 0.49; P = 0.003).

CONCLUSION

In adult female patients with a BMI in the range of 15-30 kg · m(-2), the duration of action of rocuronium increases with BMI when the drug is administered on the basis of mg per actual kg body weight.

Interaction between mivacurium and pancuronium: impact of the order of administration

INTRODUCTION

Potentiation of mivacurium by low-dose pancuronium is mostly due to an inhibition of plasma butyryl cholinesterase (BchE) resulting in a decreased rate of hydrolysis of mivacurium. Nevertheless, an interaction at the receptor site could not be ruled out. By changing the order of the muscle relaxant injections, we may lessen the pharmacokinetic interaction and assess the impact at the acetylcholine receptor level.

METHODS

Twenty patients scheduled for general anesthesia with propofol and fentanyl, and isoflurane were randomized into two groups receiving, mivacurium 100 microg kg-1 followed by pancuronium 15 microg kg-1 (group 1) or pancuronium 15 microg kg-1 followed by mivacurium 100 microg kg-1 (group 2). BchE before and after injection of each relaxant was measured. Neuromuscular block was assessed with a force transducer at the adductor pollicis measuring the elicited twitch to ulnar nerve stimulation.

RESULTS

The neuromuscular block was greater when pancuronium was administered before mivacurium (100% versus 96+/-3%; P<0.05). Times to recovery of the elicited twitch response to 25% and 75% of control value were increased by 100% (P<0.05). After pancuronium, decreases in BchE of 11% and 14% in groups 1 and 2 were observed, respectively.

CONCLUSION

Interaction between mivacurium and low dose pancuronium is significant only when mivacurium is injected after pancuronium.

Selecting neuromuscular-blocking drugs for elderly patients

The physiological changes that occur with increasing age can have significant effects on the pharmacokinetics of neuromuscular-blocking drugs. Changes in cardiac output can affect drug distribution and therefore the speed of onset of neuromuscular block. A decrease in muscle mass and increase in body fat with age can also affect their distribution. The deterioration in renal and hepatic function associated with aging affects the clearance and elimination of many neuromuscular-blocking drugs. The effects of these physiological changes on the pharmacokinetics of neuromuscular-blocking agents may not become apparent clinically in healthy individuals until the age of at least 75 years. There is very little evidence to suggest any alteration in the sensitivity of the neuromuscular junction to neuromuscular-blocking drugs with increasing age. Neuromuscular-blocking drugs that undergo a significant degree of organ-dependent elimination, such as pancuronium bromide, vecuronium bromide, rocuronium bromide and doxacurium chloride, may have a significantly prolonged duration of action in elderly patients. These drugs can be used safely in elderly patients if the anaesthetist is aware of their altered pharmacokinetics in this patient group. Appropriate changes must be made to drug dosage and dose intervals. As the pharmacokinetic changes can be unpredictable, monitoring of neuromuscular block is strongly advised when using these drugs in such patients. The risk of residual block occurring postoperatively after the use of pancuronium bromide increases with age. The duration of action of mivacurium chloride may also be prolonged in the elderly; this change has not been demonstrated to be a result of an alteration in plasma cholinesterase activity. In contrast, there is no evidence of an alteration in the action of suxamethonium chloride (succinylcholine chloride) with increasing age. Atracurium besilate and cisatracurium besilate undergo predominantly organ-independent elimination. Onset of block with these two drugs may be prolonged in the elderly, but their clinical duration of action does not alter significantly with age, making them particularly suitable for use in this patient group. Although atracurium besilate may cause histamine release, there is little evidence of it producing haemodynamic changes in the elderly. Its (1R,1R')-isomer, cisatracurium besilate, has very little direct or indirect cardiovascular effect and is, therefore, the most suitable nondepolarising agent to use in elderly patients.