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Biomedical subjects

A F Kopman

Publications and source records attributed to A F Kopman.

At least 19 recordsLinked to original sources
PubMed1991

Tactile evaluation of train-of-four count as an indicator of reliability of antagonism of vecuronium- or atracurium-induced neuromuscular blockade.

Recent evidence suggests that edrophonium is not the agent of choice to reverse profound neuromuscular blockade but remains an efficacious drug when the level of neuromuscular blockade to be antagonized is modest. We studied 90 healthy adults in an attempt to address the questions: 1) How much variability in such neuromuscular parameters as single twitch height and the train-of-four (TOF) fade ratio (T4/T1) exist when the TOF count first returns to four palpable responses? 2) Is edrophonium a reliable antagonist at this measured point of recovery? 3) What is the optimal dose of edrophonium needed to produce prompt (less than 10 min) and satisfactory (T4/T1 greater than 0.7) reversal when the fourth response of the thumb to indirect TOF stimulation just becomes palpable? Patients were given a bolus atracurium or vecuronium (n = 45 in each group) followed by an iv infusion sufficient to maintain single twitch as measured by electromyography at 10-15% of control values. At the end of surgery, the infusion was terminated and spontaneous recovery was allowed to begin. Once the tactile TOF count was four, edrophonium 0.3, 0.5, or 0.75 mg/kg was administered. At a count-of-four the first twitch averaged 37% of control (+/- 8.5% standard deviation; pooled data from all groups) and the mean T4/T1 ratio was 0.14 +/- 0.049. After atracurium neuromuscular blockade, edrophonium 0.3 mg/kg produced adequate antagonism in 10 min. At this time the mean T4/T1 ratio was 0.79 +/- 0.07 and the lowest observed value was 0.67. Increasing the edrophonium dose to 0.75 mg/kg accelerated recovery by 4-5 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A defasciculating dose of d-tubocurarine causes resistance to succinylcholine.

Forty-four patients, ASA physical status I or II, undergoing thiamylal, fentanyl, N2O/O2 anaesthesia were studied to determine the dose-response to succinylcholine (Sch) without prior defasciculation (24 pt - Group 1), or three minutes following d-tubocurarine (dTC), 0.043 mg.kg-1 (20 pt - Group 2). The individual log dose-logit response curve for each patient was determined using a cumulative dose plus infusion technique and integrated EMG monitoring of the first dorsal interosseous muscle. The mean (+/- SEM) ED50, ED90 and ED95 values for Sch in Group 1 were 0.13 +/- 0.01, 0.19 +/- 0.01 and 0.22 +- 0.01 mg.kg-1, and in Group 2 were 0.16 +/- 0.01, 0.25 +/- 0.01 and 0.29 +/- 0.02 mg.kg-1, respectively. The mean ED values in Group 2 were significantly greater than the equivalent values in Group 1 (P less than 0.05). Compared with values in Group 1, ED values in Group 2 represented mean increases of 23, 32, and 32 per cent, respectively. These pharmacodynamic data indicate that the dose of Sch needs to be increased by 32 per cent following a defasciculating dose of dTC 3 mg.70 kg-1 (0.043 mg.kg-1).

Adult↗
PubMed1989

Pancuronium, gallamine, and d-tubocurarine compared: is speed of onset inversely related to drug potency?

The relative potency and speed of onset of action of pancuronium, gallamine, and d-tubocurarine was studied in 55 adult female patients receiving nitrous oxide/oxygen-narcotic anesthesia. The integrated electromyogram of the adductor pollicis muscle was monitored using a cumulative dose-response technique; train-of-four stimuli were administered at 0.05 Hz. The measured ED95 values for pancuronium and gallamine were 0.069 and 2.38 mg/kg, respectively. In three separate groups, pancuronium 0.07 mg/kg, gallamine 2.4 mg/kg, or d-tubocurarine 0.45 mg/kg were given as a single bolus and the speed of onset and time to maximum effect determined. Peak twitch depression was essentially identical in all groups (92.7 +/- 1.4 [SE] vs. 93.3 +/- 1.1 vs. 93.7 +/- 1.1%, respectively). The rate of onset of neuromuscular blockade in these three groups was, however, quite different. After administration of pancuronium (n = 10) the times to 5%, 20%, 50%, and 80% twitch depression were 68 +/- 5, 97 +/- 6, 141 +/- 8, and 222 +/- 18 s. The comparable times following gallamine (n = 10) were 29 +/- 2, 42 +/- 3, 66 +/- 5, and 136 +/- 14 s; d-tubocurarine (n = 10) was intermediate in speed with onset times of 40 +/- 4, 63 +/- 6, 99 +/- 11, and 178 +/- 25 s. It appears that the onset times of different nondepolarizing blocking agents (even when given in equipotent doses) may vary by clinically appreciable amounts. The results of this study support the hypothesis that nondepolarizing neuromuscular blocking agents of low potency may have a more rapid onset of action than that seen with agents of high potency.

Adult↗
PubMed1986

Recovery times following edrophonium and neostigmine reversal of pancuronium, atracurium, and vecuronium steady-state infusions.

The ability of edrophonium and neostigmine to antagonize nondepolarizing neuromuscular blockade produced by steady-state infusions of atracurium, pancuronium, and vecuronium was studied in 71 adult patients anesthetized with nitrous oxide and halothane. Infusion rates of blocking drugs were adjusted so that single twitch depression as measured by the evoked integrated EMG of the hypothenar muscles was kept at 10% of control. Two minutes after the termination of the infusion either edrophonium (0.75 mg/kg) or neostigmine (0.05 mg/kg) was administered. Single twitch depression and train-of-four (T4/T1) fade was recorded during the recovery period. T4/T1 fade ratios observed at 20 min postreversal were 0.80 (atracurium-edrophonium); 0.76 (vecuronium-edrophonium); 0.44 (pancuronium-edrophonium); 0.95 (atracurium-neostigmine); 0.89 (vecuronium-neostigmine); and 0.68 (pancuronium-neostigmine). Under conditions of this study neostigmine produced more rapid and complete recovery than did edrophonium. Although edrophonium produced adequate antagonism of atracurium if 20-30 min were allowed to elapse, edrophonium reversal of pancuronium was rarely acceptable even at 30 min. Increasing the dose of edrophonium to 1.0 mg/kg produced single twitch values of 0.90 at 5 min postreversal but did not increase the rate of recovery of the train-of-four fade ratio. Neostigmine reversal of pancuronium, on the other hand, generally produced T4/T1 ratios of greater than 0.70 in 20-30 min. Although the pattern of recovery seen after reversal of vecuronium was in general quite similar to that seen after atracurium, two patients in the vecuronium-edrophonium group showed delayed recovery and also failed to respond significantly to subsequent doses of neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

Atracurium↗
PubMed1979

Edrophonium antagonism of pancuronium-induced neuromuscular blockade in man: a reappraisal.

The ability of edrophonium to reverse the nondepolarizing neuromuscular blockade produced by pancuronium was studied in 40 adult patients during light nitrous oxide--enflurane anesthesia. Antagonism of paralysis was attempted when the train-of-four fade ratio had spontaneous recovered in various extents. Edrophonium was administered in incremental doses intravenously either until the fade ratio increased to 0.70 or more or until the total dose of drug amounted to 0.5 mg/kg. All patients who had spontaneous recovery of train-of-four fade ratios to at least 0.10 had adequate reversal with edrophonium. When the train-of-four count was three or fewer visible twitches, the response to endrophonium was unpredictable. No evidence of recurarization was seen.

Edrophonium↗