Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1996
Comparative StudyA comparison of the sensitivity of epidural and myogenic transcranial motor-evoked responses in the detection of acute spinal cord ischemia in the rabbit.
Monitoring motor-evoked responses to transcranial stimulation (tc-MERs) provides information about the functional status of the spinal cord during operations that pose the risk of spinal cord ischemia. Responses can be recorded from the epidural space (epidural tc-MERs) or from muscle (myogenic tc-MERs). In this study the relative sensitivity of epidural and myogenic tc-MERs to acute spinal cord ischemia was compared. ⋯ Lower extremity ischemia as a cause of changes in myogenic tc-MER amplitude was excluded by ligating the right femoral artery and demonstrating that myogenic responses were preserved for 30 min, before occluding the aorta. We conclude that myogenic responses are more sensitive to acute spinal cord ischemia than epidural responses. The rapid detection of spinal cord ischemia with transcranial myogenic motor-evoked responses could be of clinical use in assessing the adequacy of spinal cord blood flow during operations where the spinal cord is at risk.
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Anesthesia and analgesia · Nov 1996
Comparative StudySpinal neostigmine diminishes, but does not abolish, hypotension from spinal bupivacaine in sheep.
Spinal neostigmine causes analgesia in animals and humans and abolishes hypotension from spinal bupivacaine in rats. Since drug distribution and action can vary with the size of the spinal cord, we tested the effects of the maximum tolerated dose of spinal neostigmine alone and with bupivacaine in conscious sheep. ⋯ Addition of neostigmine did not affect height of sensory block from spinal bupivacaine. These data agree with preliminary clinical reports that spinal neostigmine diminishes, but does not abolish, hypotension from spinal bupivacaine in humans.
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Anesthesia and analgesia · Nov 1996
The influence of lung volume reduction surgery on ventilatory mechanics in patients suffering from severe chronic obstructive pulmonary disease.
Recently, lung volume reduction [LVR] removal of about 20% of lung volume), has been performed to treat severe emphysema. Little is known, however, about the mechanism and time course of functional improvement, and the reasons that such patients can be tracheally extubated very early. Therefore, we studied changes in ventilatory mechanics in 12 patients after LVR. ⋯ All patients were successfully tracheally extubated within 5 h postoperatively. Immediately thereafter, a marked and sustained decrease in WOB, PEEPi, and Rawm was noted, as well as an increase in Cdyn. Ventilatory mechanics improved immediately after LVR, probably due to decompression of lung tissue, thereby enabling successful tracheal extubation.
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Anesthesia and analgesia · Nov 1996
Factors associated with hypotension and bradycardia after epidural blockade.
In order to identify patient-, anesthesia-, and surgery-related factors influencing the probability of hypotension and bradycardia after epidural blockade, an observational study was conducted on 1050 nonpregnant patients. Backward stepwise logistic regression was performed on the variables hypotension (systolic blood pressure < 90 mm Hg) and bradycardia (heart rate < or = 45 bpm). Hypotension and bradycardia occurred in 158 and 24 patients, respectively. ⋯ Sensitivity and specificity were 50% and 97%, respectively. In conclusion, our analysis can contribute to identification of patients at high risk to develop hypotension and bradycardia after epidural blockade. If bupivacaine instead of carbonated lidocaine is used and epidural fentanyl is not administered a decrease in the incidence of hypotension may be anticipated.
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Anesthesia and analgesia · Nov 1996
Thoracic epidural anesthesia improves functional recovery from myocardial stunning in conscious dogs.
The effects of thoracic epidural anesthesia (TEA) on the contractile performance of ischemic and postischemic myocardium have not been well investigated. The purpose of this investigation was to examine the effects of TEA on severity and duration of myocardial stunning in an experimental model for sublethal acute myocardial ischemia. Seven dogs were chronically instrumented for measurement of heart rate (HR), left atrial (LAP), aortic and left ventricular pressure (LVP), LV dP/dtmax' and myocardial wall-thickening fraction (WTF). ⋯ During ischemia neither the subendocardial/subepicardial nor the occluded/ normal zone blood flow was affected by TEA. TEA attenuates myocardial stunning in conscious dogs. This finding is consistent with data regarding a reduction of infarct size due to TEA.