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Biomedical subjects

L Gyermek

Publications and source records attributed to L Gyermek.

18 recordsLinked to original sources
PubMed1992

Electromyographic monitoring of profound surgical muscle relaxation during cardiac anesthesia.

Quantitative assessment of neuromuscular block produced by large doses of nondepolarizing neuromuscular blocking agents during cardiac surgery is not possible with conventional methods of monitoring. Various "posttetanic responses" can, however, be elicited, even when no twitch response is present. Posttetanic responses measured by electromyography were used in this study. Twenty-four male patients undergoing coronary bypass surgery were anesthetized with sufentanil plus diazepam. Neuromuscular block was provided either with pancuronium 0.1 mg/kg or with vecuronium 0.07 mg/kg initially and supplemented with small increments when indicated. Neuromuscular block was monitored from the hypothenar muscle. The ulnar nerve was stimulated by train-of-four, with superimposed periodic tetanic stimuli to evoke posttetanic responses, once every 7 to 15 minutes. The tetanically potentiated responses were detectable during 96% +/- 3.6 (vecuronium) and during 97% +/- 3.7 (pancuronium) of the entire intraoperative period, while the non-potentiated electromyographic responses were present for less than 50% of the time. The sum (of the amplitudes) of 6 posttetanic responses is significantly (p less than 0.05) greater than the sum of 6 nonpotentiated responses and than the size of a single-peak posttetanic response when compared with the normal, nonpotentiated responses. Higher-frequency tetanic stimuli (100 or 200 Hz) produced greater posttetanic responses (p less than 0.05) than did the 50-Hz tetanic stimulus. There were only slight or no significant differences in the degree of posttetanic potentiation between pancuronium and vecuronium either before, during, or after cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1992

"Train-of-four" fade during clinical nondepolarizing neuromuscular block.

UNLABELLED: Previous clinical studies on the train-of-four (TOF) fade have used different recording techniques, anesthesia agents and muscles for measurement, thus comparison of the results has become difficult. On 49 surgical patients divided into 6 groups, we compared: 1) The TOF fade ratios (T4/T1) produced by d-tubocurarine (dTc), pancuronium (P), atracurium (A), and vecuronium (V) and 2) the influence of previously given suxamethonium on TOF ratios (dTc and P). Neuromuscular block (NMB) was monitored simultaneously by electromyography (EMG) and by mechanomyography (MMG). Differences between the TOF fade ratios of different groups were determined and statistically analyzed by ANOVA of repeated measures, 1) at onset, as compared to spontaneous recovery with the same agent, 2) between NMB agents at (a) onset and (b) during recovery. RESULTS: TOF fade was significantly more pronounced during spontaneous recovery than during onset of NMB: a) with all NMB agents, b) with both EMG and MMG responses, with bolus dose administration of the agents, c) the degrees of TOF fade significantly differed between NMB agents during onset, d) the degrees of TOF fade (MMG) were more pronounced during onset when the agents were given in incremental doses following succinylcholine as compared to degrees of fade following single bolus doses in the absence of succinylcholine. During recovery, there was also difference in the TOF fade ratios among the agents: dTc and P produced more fade than A and V.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Increased potency of nondepolarizing relaxants after poliomyelitis.

The pathophysiology of poliomyelitis and the recognition of the "post-polio syndrome" suggest that susceptibility to muscle relaxants of patients previously affected by this disease, may be altered. We compared the effects of d-tubocurarine (dTc), pancuronium (P), and gallamine (G) on two pediatric surgical patient groups: one with a previous history of polio disease, occurring 6 to 12 years prior admission (N = 30, average age: 13 yrs, weight: 43 kg) and another without history of this disease (N = 51, average age: 11 yrs, weight: 39 kg). Following uniform premedication, thiopental, N2O/O2 + narcotic (fentanyl) anesthesia was given for reconstructive surgeries. For orotracheal intubation the patients were briefly paralyzed with 0.7 mg/kg suxamethonium. The thumb adductor responses to supramaximal 1/5 Hz impulses (continuous mode) and to 50 Hz tetanic stimuli (periodically) were recorded. After full recovery from the effect of suxamethonium (100% return of the neurally evoked muscle response) cumulative ED50 values and the recovery index (minutes elapsed from 90% to 50% block of the twitch response) of the three nondepolarizing muscle relaxants were determined. The ED50 of dTc and P were significantly lower with both neuromuscular responses in the post-polio groups (dTc, N = 12 and P, N = 10) as compared to the controls (N = 24 and 18). A tendency toward lower ED50 values in the polio group was also observed with G (N = 6). The differences, however, as compared to the control group (N = 9) were not significant (P less than .2). Recovery times were identical in the polio versus non-polio groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Halogenated vapor anesthetics adversely influence edrophonium reversal.

Reversal of the pancuronium induced neuromuscular block by edrophonium was studied in different groups of male surgical patients. All groups received similar premedication and identical induction of anesthesia. Neuromuscular function was monitored by the transduced response of the thumb adductor muscle to different [e.g. 0.2, 2 and 50 counts per second (cps)] supramaximal electrical stimuli applied to the ulnar nerve. When the regimen of anesthesia maintenance included halogenated vapor anesthetics the reversal of neuromuscular block was of lesser degree than in the case of N2O/O2 + fentanyl anesthesia. The reversal of the "fade-type" (e.g. tetanic and "train of four") responses was particularly incomplete with halothane and isoflurane. Compared with edrophonium, pyridostigmine was found to be more effective under halothane anesthesia. Based on these results, edrophonium may not be the first choice in the clinical reversal of deep levels of nondepolarizing neuromuscular block in the presence of vapor anesthetics.

Adult↗
PubMedDate not supplied

Clinical evaluation of the Datex 221 neuromuscular transmission monitor for recording posttetanic electromyographic responses.

The assessment of deep neuromuscular blockade produced by nondepolarizing neuromuscular blocking agents is not possible with the conventional use of the Datex NMT-221 "relaxograph" (Datex NMT-221 monitor, Datex Instrumentarium, Helsinki, Finland), an otherwise useful electromyographic (EMG) monitoring device. A method whereby the relaxograph can be adapted to quantitatively measure posttetanic responses is described here. In anesthetized adult patients, neuromuscular blockade was monitored simultaneously on both hands with two relaxographs. On one hand, EMG responses of hypothenar muscles to the built-in 1/20-second sequence of train-of-four stimuli of the monitor were used. On the other hand, similar recordings were made with the addition of periodically superimposed supramaximal tetanic stimuli of 100 Hz to the ulnar nerve. Neuromuscular block was provided with pancuronium. The time courses of the spontaneous recovery of the first of the train-of-four EMG responses were compared in the stimulated and control arms. At the end of the surgery, the neuromuscular block was pharmacologically reversed with atropine and neostigmine. If no tetanic stimuli were applied, the EMG responses were identical in both arms during the spontaneous recovery from the neuromuscular blockade. If tetanic stimuli were applied every 4 or 7 minutes, the rate of recovery in the stimulated hand usually exceeded that of the control hand. However, no significant difference was observed in the recovery rate when the tetanic stimuli were spaced at 15-minute intervals. Pharmacologic reversal by atropine and neostigmine was found to be identical in all patient groups. The author concludes that the Datex relaxograph is suitable for the quantitative assessment of profound surgical neuromuscular blockade with the described modification.

Adolescent↗