Direct effects of fentanyl on canine coronary artery rings.

The potent opioid fentanyl, is commonly used as a general anesthetic for coronary artery bypass surgery. Experiments were designed to determine the direct effects of fentanyl on unstimulated coronary artery tissue. Isolated, endothelium denuded canine epicardial rings were suspended in physiologic tissue baths.

Sympathovagal effects of spinal anesthesia assessed by heart rate variability analysis.

Heart rate variations (HRV) result from moment-to-moment changes in sympathetic and parasympathetic activity in response to many conditions. These two neural inputs to the heart can be identified by analyzing power spectra of HRV for frequency components at the vasomotor (low-frequency [LF]) and the respiratory (high-frequency [HF]) rhythms. HRV analysis has been used successfully in humans to noninvasively evaluate the autonomic responses to specific maneuvers and drugs, as well as responses to more chronic preexisting pathologic conditions.

Direct effects of propofol (2,6-diisopropylphenol) on canine coronary artery ring tension.

1. The direct effect of the intravenous general anesthetic propofol (2,6-diisopropylphenol) on epicardial coronary artery tone was studied in unstimulated canine coronary artery rings. 2.

Assessment of neuromuscular function in infants.

This study was conducted to measure neuromuscular transmission in newborn infants. Age-dependent differences in neuromuscular transmission and the effect of nitrous oxide anesthesia upon neuromuscular function were assessed in pediatric surgical patients following induction of anesthesia with methohexital by the use of the frequency sweep electromyogram (FS-EMG). Children older than 12 weeks' chronologic age usually had FS-EMG responses similar to those of adults, whereas infants less than 12 weeks old had significantly less pronounced FS-EMG responses at high stimulation frequencies (>50 Hz).

The relationship between receptor occlusion and the frequency sweep electromyogram during competitive neuromuscular blockade.

The purpose of this study was to correlate the frequency sweep electromyogram (FS-EMG) responses to various levels of receptor occlusion during partial neuromuscular blockade by d-tubocurarine (dTC). The FS-EMG represents the integrated compound muscle action potential induced by intra-muscular electrical stimulation as the stimulus frequency increases exponentially from 1 to 100 Hz. The FS-EMG response was recorded from the tibialis anterior muscles of six adult cats at different levels of neuromuscular blockade during recovery from intravenously injected dTc, 0.

Frequency sweep analysis of neuromuscular junction continuity.

A new technique for measuring neuromuscular junction continuity is described. Junctional transmission is evaluated by integration of the electromyographic (EMG) response induced by intramuscular electrical stimulation. The unique characteristics of this monitoring technique are the use of intramuscular stimulation and a varying stimulation rate.

Frequency sweep electromyogram and voluntary effort in volunteers after d-tubocurarine.

A new method for monitoring the effect of muscle relaxants on the myoneural junction was tested in unanesthetized volunteers. Evoked electromyographic responses to stimulation, sweeping exponentially from 1 to 100 Hz over 10 seconds, were recorded from the hand and abdominal muscles. d-Tubocurarine (dTc) was given intravenously in incremental doses until head lift was abolished.