Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1993
Median nerve blockade during diagnostic intravenous regional anesthesia as measured by somatosensory evoked potentials.
Intravenous regional anesthesia (IVRA) may be used as a diagnostic method in patients suffering from chronic pain in the forearm or hand to differentiate the origin of pain within the anesthetic area from that above. For this purpose it needs to be proven that all nerve fibers are blocked and that conduction blockade induced by IVRA takes place within the nerve trunks. Therefore the transmission of impulses in a nerve trunk to the central nervous system has been studied. ⋯ The changes in latency and amplitude of SSEPs from the scalp as well as SNAPs and SSEPs from the neck were similar. Because SSEPs, SNAPs, and the pain sensation following median nerve stimulation disappeared during IVRA, it may be concluded that the thick and thin myelinated nerve fibers of the median nerve have been blocked. For diagnostic use, IVRA is superior to peripheral nerve blockade, which has been shown previously to not abolish SSEPs.
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Anesthesia and analgesia · Jan 1993
Comparative StudyElectrocardiographic changes during cesarean section: a cause for concern?
A Holter monitor was used to record ST segment changes during cesarean section in 170 consecutive healthy parturients starting 2 h before and ending 3 h after surgery. Lumbar epidural anesthesia (LEA, n = 120) or subarachnoid anesthesia (SA, n = 50) was used. Transthoracic 2-D echocardiograms were obtained in 30 patients from the LEA group. ⋯ The operative events, alone or in combination, including hypertension, tachycardia, hypotension, bradycardia, air embolism (precordial Doppler) were neither specific nor sensitive as predictors of ST segment change (stepwise logistic regression). Tachycardia was associated with ST segment changes in 10% of time epochs (5 min) (P = 0.05, x2 analysis). Thus, ST segment changes during cesarean section are not caused by myocardial ischemia and are not of any clinical consequence.
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Anesthesia and analgesia · Jan 1993
Comparative StudyWork hours of residents in seven anesthesiology training programs.
Medical educators and credentialing organizations recently have called attention to the long hours that some house staff are required to spend in the hospital during training. To determine the average duration of in-hospital work hours of anesthesiology residents, 148 residents at seven, university-affiliated training programs kept daily logs of their activities for one week. Residents in clinical anesthesia years 1, 2, and 3 spent an average of 66, 65, and 64 hours per week, respectively, in the hospital with a range of 43 to 104 hours per week. ⋯ The largest portion of the in-hospital time was devoted to patient care activities in the operating room. Residents had time for educational activities, conferences, and reading while in the hospital. The overall work hours of the residents in the anesthesiology training programs included in this survey appeared to be within current guidelines.
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Anesthesia and analgesia · Jan 1993
Propofol produces endothelium-independent vasodilation and may act as a Ca2+ channel blocker.
The mechanism of vasodilation induced by propofol was investigated using isolated rat thoracic aortic rings. Aortic rings were precontracted with potassium chloride (KCl) (40 mM) or phenylephrine (PE) (3 x 10(-8) to 3 x 10(-7) M) in the presence and absence of intact endothelium. Propofol produced similar concentration-dependent relaxation in aortic rings with and without endothelium regardless of whether they were precontracted with KCl or PE. ⋯ These effects are similar to those produced by verapamil. Propofol (5 x 10(-5) M) had minimal effect on the intracellular Ca2+ release elicited by PE (10(-5) M). We conclude that vasodilation produced by propofol is not endothelium-dependent but is likely due to blockade of voltage-gated influx of extracellular Ca2+.