mivacurium and Flushing

The dose-effect relationship of mivacurium chloride on arterial blood pressure, heart rate, and plasma histamine was determined in 97 consenting ASA physical status I-II patients receiving nitrous oxide-oxygen-opiate-barbiturate anesthesia. In the absence of surgical stimulation during steady state anesthetic conditions with controlled ventilation, average maximum change in tachograph-counted heart rate was 7% or less after 10-15-s injection of mivacurium at all doses from 0.03 to 0.30 mg/kg. Average peak change in mean arterial pressure measured via radial arterial catheter was 7% or less after all doses from 0.03 to 0.15 mg/kg. Transient (0.2-4.5 min) decreases in arterial blood pressure were noted after 10-15-s injection in some patients at 0.20, 0.25, and 0.30 mg/kg. When they occurred, these changes were usually accompanied by facial erythema lasting 2-5 min and were correlated with increases in plasma histamine level (P less than 0.001). Facial erythema, decrease in blood pressure, and elevation of histamine level were all accentuated by increasing the dose of mivacurium and by more rapid injection of the drug. For example, mean blood pressure decreased an average of 13% after injection of mivacurium 0.25 mg/kg over 10-15 s. In contrast, during administration over 30 and 60 s of this dose, arterial pressure decreased 7.6 and 1.5%, respectively (P less than 0.001, 10-15 s vs. 60-s injection). Average peak histamine level, which increased to 132% of control after administration of 0.25 mg/kg over 10-15 s, did not change after injection over 60 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Analgesics, Opioid; Anesthesia, General; Barbiturates; Blood Pressure; Clinical Trials as Topic; Dose-Response Relationship, Drug; Flushing; Heart Rate; Histamine; Humans; Isoquinolines; Middle Aged; Mivacurium; Nerve Block; Neuromuscular Nondepolarizing Agents; Nitrous Oxide

The significance of plasma cholinesterase (pChe) activity for the duration of action of mivacurium in phenotypically normal patients was evaluated in 35 patients during neurolept anaesthesia. The response to train-of-four nerve stimulation was recorded using a Myograph 2000. Ten patients with normal pChe (Group I) and five patients with decreased pChe activity (Group 2) were given a small test dose of mivacurium 0.03 mg kg-1. Mivacurium 0.1 mg kg-1 was administered following spontaneous recovery from the first dose. The mean suppression of the height of the first (T1) of the train-of-four responses following mivacurium 0.03 mg kg-1 patients with normal and decreased enzyme activity was 40% and 56%, respectively, and the mean T1 suppression after mivacurium 0.1 mg kg-1 was 100% in both groups. The times to different levels of twitch height recovery following the 0.1 mg kg-1 dose did not differ between the two groups of patients. Another 20 patients with normal or decreased pChe activity (Group 3) were given mivacurium 0.2 mg kg-1. In this group the time to maximum block was 1.4 min (1.0-4.0) mean (range) and the time to reappearance of the T1 response was 15.0 min (7.4-22.7) (range). An inverse relationship was found between the patients' pChe activity and the time to first response. It is concluded that mivacurium is short-acting in patients with normal pChe phenotype and normal to low-normal pChe activity. No patient with very low pChe activity was included in the study. A prolonged response to mivacurium may, however, be expected in these patients.

Topics: Anesthesia Recovery Period; Cholinesterases; Dibucaine; Electric Stimulation; Flushing; Humans; Infusions, Intravenous; Isoquinolines; Mivacurium; Muscle Contraction; Neostigmine; Neuromuscular Junction; Neuromuscular Nondepolarizing Agents; Phenotype; Reaction Time; Time Factors; Ulnar Nerve