Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1992
Randomized Controlled Trial Comparative Study Clinical TrialComparison of the anesthetic requirement for tolerance of laryngeal mask airway and endotracheal tube.
We tested the hypothesis that the laryngeal mask airway (LMA) is tolerated at lighter levels of anesthesia than an endotracheal tube (ET). We studied 20 unpremedicated, nonsmoking ASA physical status I or II patients aged 18-40 yr whose surgery lasted > 1 h. Subjects were randomly assigned to receive either an ET or LMA. ⋯ The patient was observed for signs of reaction to the presence of the LMA or ET. The mean (range) end-tidal isoflurane concentrations for reaction to ET and LMA were 0.55% (0.4-0.7) and 0.35% (0.2-0.51), respectively (P < 0.001). These data confirm the original hypothesis of the study.
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Anesthesia and analgesia · Nov 1992
Effects of surgical stress and volatile anesthetics on left ventricular global and regional function in patients with coronary artery disease. Evaluation by computer-assisted two-dimensional quantitative transesophageal echocardiography.
We investigated the effects of halothane, enflurane, and isoflurane on central hemodynamics and left ventricular global and regional function when used to control intraoperative hypertension in 39 patients with coronary artery disease. Left ventricular short-axis, midpapillary images were obtained by transesophageal echocardiography. Using a centerline algorithm, we analyzed left ventricular images for global area ejection fraction (GAEF) and segmental area ejection fraction (SAEF). ⋯ Isoflurane induced a decrease in the SAEF/GAEF ratios of two segments corresponding to the inferolateral wall of the left ventricle that was, in one of these segments, significantly more pronounced compared with both halothane and enflurane. Halothane or enflurane did not cause any change in regional wall motion. We conclude that isoflurane is more likely to cause regional wall motion changes than halothane or enflurane in patients with coronary artery disease.
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Anesthesia and analgesia · Nov 1992
Comparative StudyTotal intravenous anesthesia: effects of opioid versus hypnotic supplementation on autonomic responses and recovery.
During radical prostatectomy procedures under total intravenous anesthesia, acute hemodynamic responses to retropubic dissection (30% +/- 8% to 36% +/- 12% [mean +/- SD] increases in mean arterial pressure) were treated with supplemental doses of either an opioid analgesic (alfentanil) or a sedative-hypnotic (propofol) to return the mean arterial pressure to within 10% of the preincision value. Although both drugs were effective, control with propofol required 10.1 +/- 2.5 min compared with 6.3 +/- 2.6 min in the alfentanil group (mean +/- SD; P < 0.01). Plasma stress hormone concentrations increased significantly in response to this surgical stimulus: epinephrine increased from 246% +/- 169% to 283% +/- 330%; norepinephrine increased from 44% +/- 33% to 83% +/- 104%; and antidiuretic hormone increased from 1300% +/- 1591% to 1700% +/- 1328%. ⋯ In addition, 36% of the alfentanil-treated patients required antihypertensive therapy in the postanesthesia care unit compared with only 9% in the propofol group (P < 0.05). Postanesthesia care unit and hospital discharge times were similar in both treatment groups. We conclude that supplemental doses of alfentanil or propofol were equally effective in controlling acute hemodynamic and hormonal responses to surgical stimuli during total intravenous anesthesia.
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Anesthesia and analgesia · Nov 1992
Comparative StudyA comparison of methods for the detection of myocardial ischemia during noncardiac surgery: automated ST-segment analysis systems, electrocardiography, and transesophageal echocardiography.
Clinicians often fail to detect intraoperative ischemic electrocardiographic (ECG) changes when viewing oscilloscopes. Automated ST-segment monitors promise to increase the detection of such ECG changes. We investigated the capacity of two commercially available ST-segment monitors to detect intraoperative myocardial ischemia in patients at high risk for developing intraoperative myocardial ischemia during vascular and other noncardiac procedures. ⋯ Comparison of the printed ECG with TEE revealed that ST-segment changes in the printed ECG, as analyzed by a cardiologist, were 25% sensitive and 62% specific for the detection of TEE-diagnosed myocardial ischemia. When T-wave inversions were added to ST-segment depression as a criterion for the diagnosis of myocardial ischemia by the printed ECG, the sensitivity of ECG for the detection of intraoperative myocardial ischemia, as determined by TEE, was 40% and specificity was 58%. Twenty-three of the 44 patients were simultaneously monitored in leads I, II, and V5 with an automated Marquette ST-segment monitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Nov 1992
Comparative StudyPreoxygenation of pregnant and nonpregnant women in the head-up versus supine position.
The influence of preoxygenation in the supine (n = 10) versus the 45 degrees head-up (n = 10) position on the duration of apnea leading to a decrease in arterial oxygen saturation to 95%, as monitored by pulse oximetry, was investigated in 20 women undergoing elective cesarean section at term of pregnancy. The results were compared with those obtained in a control group of 20 nonpregnant women. ⋯ We conclude that pregnant women desaturate their arterial blood of oxygen more rapidly than do nonpregnant women. Furthermore, the head-up position extends the duration of apnea that can take place before desaturation occurs in nonpregnant patients.