Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1996
Comparative StudyAcoustic reflectometry and endotracheal intubation.
To determine whether acoustic reflection measurement of the upper airway can be used to identify tracheas that are difficult to intubate, we conducted a pilot study of adults with a documented history of unexpected failed endotracheal intubation (16 cases) and compared them with 16 controls with previous successful intubation. The two groups were matched by age, sex, height, and weight. ⋯ For supine position with the neck extended, all patients who had been successfully intubated had pharyngeal volumes more than 43.4 mL (mean +/- SD, 56.9 +/- 8.3 mL), whereas pharyngeal volumes were less than 37.5 mL in all patients who had a history of unexpected failed intubation (mean +/- SD, 19.7 +/- 10.2 mL; P < 0.05). Using a cutoff of 40.2 mL, acoustic reflection enabled us to distinguish between patients with previous unexpected failed endotracheal intubation and those with previous successful intubation.
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Anesthesia and analgesia · Nov 1996
Intraoperative jugular desaturation during surgery for traumatic intracranial hematomas.
Traumatic intracranial hematomas which are present on hospital admission or which develop during the hospital course are associated with a worse neurological outcome than diffuse injuries. The purpose of this study was to monitor jugular venous oxygen saturation (Sjvo2) during surgery for evacuation of traumatic intracranial mass lesions, to determine the incidence and the causes of jugular venous desaturation, and to assess the usefulness of Sjvo2 monitoring in this setting. Twenty-five severely head injured patients were monitored during 27 surgical procedures. ⋯ Hypotension (mean arterial pressure < 80 mm Hg) was a contributing factor in seven of the cases of jugular desaturation. The definitive treatment of a traumatic intracranial hematoma is surgical evacuation. However, during the period prior to evacuation of the hematoma, jugular venous desaturation was common, suggesting that monitoring Sjvo2 might provide useful information about the adequacy of cerebral perfusion.
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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
Orthostatic hypotension during postoperative continuous thoracic epidural bupivacaine-morphine in patients undergoing abdominal surgery.
Fifty patients undergoing colonic surgery received combined thoracic epidural and general anesthesia followed by continuous epidural bupivacaine 0.25% and morphine 0.05 mg/mL, 4 mL/h, for 96 h postoperatively plus oral tenoxicam 20 mg daily. Heart rate (HR) and arterial blood pressure (BP) were measured at supine rest, during orthostatic stress, and after walking prior to and 24, 48, and 72 h and 48 h postoperatively compared to preoperatively (P < or = 0.008); 16 vs 6 patients presented resting systolic BP values < 100 mm Hg (lower range, 70 mm Hg) post- versus preoperatively (P = 0.048). During orthostatic stress the decrease in systolic BP and concomitant increase in HR was similar post- versus preoperatively (BP, P > 0.3; HR, P > 0.34) and 12 vs 8 patient; (P = 0.45) experienced a systolic BP decrease > 20 mm Hg post- versus preoperatively. ⋯ Epidural infusion was discontinued in three patients due to either persisting resting or orthostatic hypotension. There was no correlation between ASA classification, intraoperative bleeding, or postoperative dizziness and incidence of orthostatic hypotension. The results suggest that patients undergoing abdominal surgery and treated with continuous small-dose thoracic epidural bupivacaine-morphine are subjected to a decrease of BP at rest and during mobilization, but not to an extent that seriously impairs ambulation in most patients.
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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.