[Evaluation of muscle relaxant requirement for hospital anesthesia].

The rationale for cost-effectiveness of modern muscle relaxants (MR) administration in general anesthesia was evaluated. New MRs are more expensive than traditionally used pipecuronium and succinylcholine. However, the old MRs are often required as a block reversion with anticholinesterase medicines at the end of surgery, the longer artificial lung ventilation and observation in patients during recovery in intensive care unit. It was found that the district military hospital had done an annual average of about 900 general anesthesia assisted with artificial ventilation and muscle relaxation. About 2% of all anesthesias accrue to short-term anesthesia, the 27% to medium-term and 71% to long-term. 81% of the medium-term anesthesia accrue small hospitals. According to cost/effectiveness the most optimal muscle relaxants administration scheme for short-term (up to 30 min) anesthesia was mivacurium, for the operation of medium duration (30-120 min)--rocuronium, for long-term (120 min)--pipecuronium. An electronic form of annual report, which allows to obtain the necessary data for calculation of annual muscle relaxants demand and costs both in hospital and in the whole of the armed forces quickly, was developed.

Cholinesterase unit establishment and issuing of >>Warning Cards<< for carriers of suxamethonium sensitive serum butyrylcholinesterase variants.

Recognition of butyrylcholinesterase (EC 3.1.1.8) variants in human serum is essential to identify patients who may be susceptible to a prolonged reaction of suxamethonium and mivacurium, short-acting muscle relaxants. Thus they can be given appropriate advice along with their relatives who may be similarly affected. Therefore, Cholinesterase Unit for detection of individuals, carriers of inherited suxamethonium sensitive butyrylcholinesterase variants was established at the Institute for Clinical Chemistry of the Clinical Hospital >>Merkur<<, Zagreb, Croatia. A study was conducted on sera from patients referred to the Unit. Butyrylcholinesterase variants were determined by measuring the enzyme activity and inhibition by specific inhibitors in the sera of 384 patients and of the members of seven families. Cholinesterase Unit issued >>Warning Cards<< to the carriers of inherited serum butyrylcholinesterase variants in order to avoid prolonged apnea that suxamethonium might cause.

Cost analyses of remifentanil, mivacurium and ropivacaine - a systematic review.

Remifentanil, mivacurium and ropivacaine are the latest innovations in clinical anaesthesia and have gained increasing importance in daily practise due to their unique pharmacodynamic and pharmacokinetic properties. However, drug acquisition costs for these agents are considerably higher in most countries than for comparable substances. This review provides a systematic, critical appraisal of pharmacoeconomic studies with remifentanil, mivacurium and ropivacaine, primarily based on prospective, randomised trials. Results from analyses using cost-minimising techniques stress the issue of the higher drug acquisition costs. However, studies using a more sophisticated method (e.g., cost-effectiveness analysis) indicate comparable costs or even financial advantage in favour of the newer investigative drugs remifentanil, mivacurium and ropivacaine.

[Frequency distribution of dibucaine numbers in 24,830 patients]. / Verteilungsmuster der Dibucainzahl bei 24.830 Patientinnen und Patienten.

PURPOSE: Atypical cholinesterase prolongs the duration of neuromuscular blocking drugs such as succinylcholine and mivacurium. Measuring the dibucaine number identifies patients who are at risk. This study shows the frequency distribution of dibucaine numbers routinely measured and discusses avoidable clinical problems and economic implications. METHODS: Dibucaine numbers were measured on a Hitachi 917-analyzer and all dibucaine numbers recorded over a period of 4 years were taken into consideration. Repeat observations were excluded. RESULTS: A total of 24,830 dibucaine numbers were analysed and numbers below 30 were found in 0.07% ( n=18) giving an incidence of 1:1,400. Dibucaine numbers from 30 to 70 were found in 1.23% ( n=306). On the basis of identification of the Dibucaine numbers we could avoid the administration of succinylcholine or mivacurium resulting in a cost reduction of 12,280 Euro offset against the total laboratory costs amounting to 10,470 Euro. CONCLUSIONS: An incidence of 1:1,400 of dibucaine numbers below 30 is higher than documented in the literature. Therefore, routine measurement of dibucaine number is a cost-effective method of identifying patients at increased risk of prolonged neuromuscular blockade due to atypical cholinesterase.

[Quantitative assessment of neuromuscular block of the orbicularis oculi muscle]. / Quantitative Erfassung der neuromuskulären Blockade des Musculus orbicularis oculi.

In a prospective clinical study neuromuscular block at the orbicular ocular muscle was examined qualitatively and quantitatively by an AMG approach. The signals were recorded, visualized and evaluated simultaneously under PC-support after TOF-stimulation in 20 s intervals. Fifty ASA I and II patients were included into the study. After oral premedication with midazolam 10-15 mg, anaesthesia was induced with propofol 2 mg/kg and alfentanil 0.02 mg/kg and maintained by means of propofol 6-8 mg/kg/h and alfentanil 0.02 mg/kg/h. After intubation and signal stabilization, mivacurium 0.75 mg/kg was administered and neuromuscular blockade was recorded online. The measured acceleration at the orbicular ocular muscle amounted 0.9 g on average. Maximal neuromuscular block was registered at 78.5% and the TOF-ratio of 0.8 was achieved after 14.1 min. The low values of the AMG-signals of the orbicular ocular muscle requiring very high technical demands on the measuring instrument. Additional problems arise through the considerable temporal expenditure for discovering the optimal location of stimulation. During the AMG monitoring the position dependence of the measured values of the sensors must be taken into consideration. These technical problems restrict the suitability of the AMG at the orbicular ocular muscle as a quantitative neuromuscular monitoring tool.

Equi-lasting doses of rocuronium, compared to mivacurium, result in improved neuromuscular blockade in patients undergoing gynecological laparoscopy : [Des doses de durée équivalente de rocuronium, comparé au mivacurium, améliorent la curarisation chez des patientes qui subissent une laparoscopie gynécologique].

PURPOSE: To compare equi-lasting doses of a short-acting (mivacurium) to an intermediate-acting (rocuronium) neuromuscular relaxant, with regard to intubating conditions, efficacy, number of maintenance doses, hemodynamic alterations, adverse events and costs, in patients undergoing laparoscopic gynecological surgery. METHODS: Sixty patients were randomly allocated to receive either 0.2 mg*kg(-1) (3 x ED(95)) mivacurium or 0.5 mg*kg(-1) (1.7 x ED(95)) rocuronium, under propofol/fentanyl anesthesia. T1, first twitch of the train-of-four (TOF) and TOF ratio (T4:T1) were used to evaluate neuromuscular block using the Relaxometer(R) mechanomyograph. The trachea was intubated when T1 was maximally suppressed. Neuromuscular block was maintained at 25% T1 with equi-lasting doses of 0.075 mg*kg(-1) mivacurium or 0.15 mg*kg(-1) rocuronium. RESULTS: Mean (min) +/- SD mivacurium onset time (1.9 +/- 0.4) was longer than that of rocuronium (1.3 +/- 0.3). This did not yield a statistical difference in intubating conditions between the two groups. Interval 25-75% T1 recovery and time to 0.8 TOF recovery were prolonged following rocuronium (11.9 +/- 3.9, 52.6 +/- 15.5 respectively) compared to mivacurium (6.7 +/- 2.3, 39.2 +/- 8.1 respectively). More patients, 22/30, required mivacurium maintenance doses compared to 14/30 patients in the rocuronium group. Arterial blood pressure declined and 13/30 patients manifested erythema following mivacurium administration. The acquisition costs of rocuronium (6.93 Euro/patient) were 23% lower compared to mivacurium (8.96 Euro/patient). CONCLUSION: Equi-lasting doses of rocuronium resulted in favourable intubating conditions more rapidly, improved hemodynamic stability, required less frequent administration of maintenance doses and were not associated with erythema, compared to mivacurium.

Mivacurium or vecuronium for paediatric ENT surgery. Clinical experience and cost analysis.

BACKGROUND: The present study compared the quality of neuromuscular block and costs after equipotent doses of mivacurium and vecuronium in the context of paediatric ENT surgery. METHODS: A total of 30 children undergoing elective tonsillectomy were included and randomised in two groups (n = 15 for each) according to the neuromuscular blocking agent (NMBA) used. Anaesthesia was induced with alfentanil (15 micrograms/kg), propofol (3 mg/kg) and either 0.2 mg/kg mivacurium or 0.14 mg/kg vecuronium. For maintenance of anaesthesia propofol (8-12 mg/kg/h) was given. Neuromuscular block was assessed by electromyography using train-of four stimulation and the following parameters were quantified: Twitch height (T1) 2 min after the initial bolus of the myorelaxant; duration until recovery to 10% T1, number and duration of bolus injections of the myorelaxant needed to maintain neuromuscular block to a T1 < 10%. In addition, the intubating conditions, number of patients needing pharmacological reversal at the end of surgery, adverse reactions and the costs for neuromuscular block and pharmacological antagonization were assessed. RESULTS: Intubation conditions were comparable between both study groups: mivacurium--excellent: 7, good: 5, not acceptable: 1; vecuronium--excellent: 11, good: 4 (n.s.). T1 at 2 min was 16 (15)% for mivacurium and 6 (9)% for vecuronium (P < 0.05). Time to 10% T1 recovery was 6.1 (1.7) min for mivacurium and 21.8 (3.7) min for vecuronium (P < 0.01). In the mivacurium group 7 repetitive doses (range: 4-18) were needed to maintain T1 < 10% during surgery, whereas children treated with vecuronium needed only 1 maintenance dose (range: 0-2) (P < 0.01). Two children in the mivacurium group and 11 in the vecuronium group required pharmacological reversal of the NMB at the end of surgery (P < 0.01). The overall costs of NMB were significantly higher in the mivacurium group as compared to vecuronium 12.88 (4.5) Euro vs 9.96 (2.4) Euro; P < 0.05. CONCLUSIONS: In conclusion, mivacurium-induced NMB is of very short duration in paediatric patients, and therefore repetitive doses are required to maintain a deep neuromuscular block. Nevertheless, residual paralysis is less frequent after mivacurium. The neuromuscular block after mivacurium was more expensive and residual paralysis less frequent compared to vecuronium.

The impact of price labeling of muscle relaxants on cost consciousness among anesthesiologists.

STUDY OBJECTIVE: To determine whether placing price labels on the vial caps of muscle relaxants increases cost consciousness among anesthesiologists. DESIGN: Retrospective study. SETTING: University hospital departments of anesthesia and pharmacy. MEASUREMENTS AND MAIN RESULTS: We placed price labels on the vial caps of all muscle relaxants for a study period of 1 year. At the beginning of the investigation, we informed the anesthesiologists of the study, discussed the prices for different muscle relaxants, and encouraged utilizing less expensive muscle relaxants whenever possible without compromising patient care. The price labels on the vial caps served as visual reminders of the various costs of muscle relaxants during daily practice. We compared the total amount spent on each muscle relaxant during the period from October 1993 to September 1994 with the period from October 1994 to September 1995. The total number of surgical cases from October 1993 to September 1994 and from October 1994 to September 1995 was unchanged and equaled 20,389 and 20,358 cases, respectively. Expenditures for pancuronium increased 104.1%. Total expenditure decreased by 12.5%, with a net savings of $47,111. CONCLUSION: Expenditures for the less costly pancuronium increased while expenditures for vecuronium and atracurium decreased. Price labeling of muscle relaxants in conjunction with education reduces total pharmacy expenditure on muscle relaxants.

The impact of choice of muscle relaxant on postoperative recovery time: a retrospective study.

UNLABELLED: To test the hypothesis that the use of long-acting muscle relaxants is associated with prolonged postoperative recovery when compared with the use of shorter-acting relaxants, we undertook a retrospective study of 270 patients with induced paralysis recovering from general anesthesia. We calculated the mean recovery time associated with each muscle relaxant used. Regression analyses were performed to control for potential confounding of the results by length and type of surgery, as well as age and sex. Taking these into account, the adjusted difference in mean recovery time between patients receiving short- and intermediate-acting relaxants (mivacurium, atracurium, and vecuronium) versus those receiving long-acting relaxants (d-tubocurarine, pancuronium, and pancuronium and d-tubocurarine combination) was 30 min (95% confidence interval [CI] 8-53). The adjusted difference in mean recovery time between patients receiving vecuronium and those receiving pancuronium (i.e., the single most frequently used drug in each category) was 33 min (95% CI 1-66). Shortened recovery time accounted for an estimated average $37.95 decrease in recovery room charge per patient when vecuronium was used instead of pancuronium, versus a $22.84 increase in drug cost. Our data and analyses support the hypothesis that the use of long-acting muscle relaxants is associated with prolonged recovery after surgery and provide preliminary evidence that restricting the use of the more expensive, shorter-acting muscle relaxants may represent a false economy. IMPLICATIONS: In this retrospective study, the use of old-fashioned, inexpensive, long-acting paralyzing drugs was found to be associated with prolonged postoperative recovery. This has implications when deciding whether, as an economic measure, to restrict the use of the more expensive, shorter-acting paralyzing drugs, because prolonged recovery also has a price.

Performance assessment of an adaptive model-based feedback controller: comparison between atracurium, mivacurium, rocuronium and vecuronium.

The performance of an adaptive model-based controller for the administration of atracurium, mivacurium, rocuronium and vecuronium was compared in 159 adult surgical patients. The degree of neuromuscular block was set to 90% for atracurium, rocuronium and vecuronium and to 95% for mivacurium. Performance was assessed by calculating the median prediction error (bias), median absolute performance error (inaccuracy), divergence, wobble, the mean offset and the mean standard deviation from the setpoint. All indices of controller performance showed minimal deviation of the actual neuromuscular block from the setpoint. Although the controller appeared to be able to control rocuronium induced block at 90% and mivacurium induced block at 95% better than atracurium and vecuronium block at 90%, the differences in the controller performance between the four studied relaxants were small and have hardly any clinical significance. We conclude that a model-based adaptive controller is useful in the administration of atracurium, mivacurium, rocuronium or vecuronium.

Recovery from mivacurium-induced neuromuscular blockade after neurosurgical procedures of long duration.

STUDY OBJECTIVE: To determine if recovery following prolonged (5 hours in length or greater) infusions of mivacurium is different from recovery after single bolus administration. DESIGN: open-labelled, controlled study. SETTING: Inpatient neurosurgical service at a university hospital. PATIENTS: 36 patients between the ages of 18 to 65 without significant history of renal, hepatic, cardiac, or metabolic disease undergoing neurosurgical procedures. 21 patients had craniotomies or skull base procedures of an estimated length of 5 hours or greater; 15 patients (control) underwent short neurosurgical operations (two hours or less). INTERVENTIONS: Intravenous (IV) mivacurium 0.15 mg/kg was given with stable general anesthesia with 70% nitrous oxide in oxygen, 0.2% to 0.3% end-tidal isoflurane, and continuous infusion of fentanyl. The control group was allowed to recover spontaneously after single bolus administration while neuromuscular blockade was maintained in the study group with a continuous infusion of mivacurium until 30 minutes before completion of surgery, at which time the infusion was discontinued and neuromuscular function was allowed to recover spontaneously. MEASUREMENTS AND MAIN RESULTS: The evoked compound electromyogram of the adductor pollicis brevis muscle was measured during stimulation of the ulnar nerve at 2 Hz for 2 seconds at 10-second intervals. Measurements included time to 50% and 90% depression of twitch (T1 of the TOF response), time to T1 equal to 25% (T1(25)), 50% (T1(50)), and 75% (T1(75)) of baseline, and TOF ratio (TR) at 10%, 25%, 50%, and 75% recovery. Recovery index (RI), which is T1(75) minus T1(25), was also determined. All mivacurium infusion rates decreased during surgery. Recovery rates were significantly longer in the long infusion (LI) group than the control group. RI was also increased in the LI group compared with the single bolus control (11.3 +/- 1.2 minutes vs. 7.1 +/- 0.8 minutes p < 0.05). CONCLUSIONS: Recovery following mivacurium by prolonged continuous infusion was slower than that observed after single bolus administration in this patient population. Clinically, this increased time to recovery may be insignificant.

The clinical and basic pharmacology of mivacurium: a short-acting nondepolarizing benzylisoquinolinium diester neuromuscular blocking drug.

Mivacurium is a benzylisoquinolinium diester. The drug is a nondepolarizing relaxant which is hydrolysed by plasma cholinesterase at 70-88% of the rate of suxamethonium. Enzymatic hydrolysis gives the drug its short duration of action. The length of paralysis is about 2-2.5 times that of suxamethonium and one-half to one-third that of the intermediate-acting nondepolarizers. The development of mivacurium represents a collaboration between industrial pharmacologists and chemists at Burroughs Wellcome Co. (USA) and investigators at the Massachusetts General Hospital, Boston, MA, USA.