ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To investigate the hemodynamic correlates of perioperative regional wall motion abnormalities (RWMA), we measured wall motion continuouslyviatransesophageal echocardiography (TEE), and related RWMA to continuously measured hemodynamic indices of myocardial oxygen supply and demand (heart rate [HR] and systemic and pulmonary arterial blood pressures). Fifty patients undergoing coronary artery bypass graft (CABG) surgery were studied throughout the prebypass, postbypass, and intensive care unit (ICU) periods. Only 28% of TEE episodes (RWMA suggestive of ischemia) were preceded by acute changes in any hemodynamic parameter. Specifically, 7% of TEE episodes were preceded by increases in HR (20% deviation from control), 14% by increases in systolic blood pressure (SBP), 13% by decreases in diastolic blood pressure (DBF), and 9% by increases in pulmonary artery diastolic pressure (PAD). Twelve per cent of TEE episodes were associated with increases in rate-pressure product (RPP) to >12,000, and 27% were associated with decreases in mean arterial pressure (MAP)/HR to <1 at the onset of TEE episodes. Comparison among periods revealed that post-bypass TEE episodes were more frequently associated with either increases in demand or decreases in supply than were prebypass episodes (53% vs. 25%,P< 0.05). ECG ischemic episodes also were infrequently (30%) associated with acute changes in HR, SBP, DBP, or PAD. We conclude that perioperative TEE episodes are infrequently triggered by changes in hemodynamics, suggesting that a primary decrease in myocardial oxygen supply may be an important mechanism for most perioperative RWMA. In addition, neither pulmonary artery catheter pressure measurements nor specialized indices (RPP and MAP/HR) appear to be useful in predicting TEE episodes.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To test the hypothesis that there are important differences between studies on memory published in anesthesia literature and those published in the psychopharmacology literature, we compared the two from the period January 1978 through May 1988 to identify deficiencies in the design and methodologies used and to provide guidelines for future experiments. Eighty-eight articles in each discipline were reviewed. The sample sizes were larger in the articles in anesthesia journals than in those in psychopharmacology journals (medians 52.5vs. 18 subjects, respectively). Most (85%) of the studies in the anesthesia literature used patients, who had a median age of 38.9 yr and included a median of 28 women among the subjects per study. In contrast, the majority (60%) of the studies in the psychopharmacology literature used healthy volunteers, who had a median age of 23.6 yr and included a median of only 3.5 females among the subjects per study. Characteristics more common in the psychopharmacology than in the anesthesia literature, respectively, were use of a control or placebo group (90%vs. 42%), double-blind design (80%vs. 47%), use of pre- and posttreatment memory measurements (64%vs. 23%), use of multiple memory tests with distinct equated stimuli (83%vs. 8%), relation of methodology to some theoretical model of memory (72%vs. 17%), and use of other behavioral tests (68%vs. 48%). Relative to the psychopharmacology literature, the anesthesia literature used pictures as stimuli for the memory tests more often (44%vs. 14%, respectively) and words less often (11%vs. 67%) and relied heavily on questions about recall of perioperative events (41%vs. 0%). There is room for improvement in both types of literature, and more so in the anesthesia literature.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Slowing and attenuation of the dominant frequency of the electroencephalogram (EEG) are changes commonly used to detect cerebral ischemia. To assess the validity of this method, the EEGs recorded during 93 episodes of circulatory arrest in ten normothermic, lightly anesthetized patients undergoing implantation of automatic internal cardioverting defibrillators (AICDs) were visually inspected for change. The number of events recorded for each patient varied from 5 to 18 and was a function of the duration and success of AICD testing in each patient. In 82 of 93 (88%) episodes, EEG changes were identified, and occurred an average of 10.2 s after the last normal heart beat. Of these 82, 67 (82%) illustrated slowing and attenuation. However, 15 (18%) of the hemodynamic events showed changes not previously described as indicative of cerebral ischemia: 6 (7%) showed a loss of delta-wave activity and 9 (11%) showed an increase in the amplitude of theta activity. Time to onset of these unusual changes (10.6 and 9.2 s, respectively) was not significantly different from that for EEG slowing and attenuation (10.2 s). Five of the ten subjects showed more than one pattern of EEG change. There was no significant difference in the time to onset of EEG change among individual patients, and neither were there differences in patterns of change associated with particular anesthetic agents. These results indicate that in normothermic, lightly anesthetized individuals, cerebral ischemia may cause changes in EEG pattern other than slowing and attenuation of dominant frequencies. These alternative patterns should be recognized as indicative of cerebral ischemia when intraoperative EEG monitoring is performed.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

More than 80 deaths have occurred after the use of midazolam (Versed*), often in combination with opioids, to sedate patients undergoing various medical and surgical procedures. We investigated the respiratory effects of midazolam (0.05 mg·kg−1) and fentanyl (2.0 μg·kg−1) in volunteers. The incidence of hypoxemia (oxyhemoglobin saturation <90%) and apnea (no spontaneous respiratory effort for 15 s) and the ventilatory response to carbon dioxide were evaluated. Midazolam alone produced no significant respiratory effects. Fentanyl alone produced hypoxemia in half of the subjects and significant depression of the ventilatory response to C02, but did not produce apnea. Midazolam and fentanyl in combination significantly increased the incidence of hypoxemia (11 of 12 subjects) and apnea (6 of 12 subjects), but did not depress the ventilatory response to CO2more than did fentanyl alone. Adverse reactions linked to midazolam and reported to the Department of Health and Human Services highlight apnea- and hypoxia-related problems as among the most frequent adverse reactions. Seventy-eight per cent of the deaths associated with midazolam were respiratory in nature, and in 57% an opioid had also been administered. All but three of the deaths associated with the use of midazolam occurred in patients unattended by anesthesia personnel. We conclude that combining midazolam with fentanyl or other opioids produces a potent drug interaction that places patients at a high risk for hypoxemia and apnea. Adequate precautions, including monitoring of patient oxygenation with pulse oximetry, the administration of supplemental oxygen, and the availability of persons skilled in airway management are recommended when benzodiazepines are administered in combination with opioids.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A need exists for a safe and effective oral preanesthetic medication for use in children undergoing elective surgical procedures. We evaluated the effectiveness of three different doses of oral midazolam when administered in combination with atropine prior to ambulatory surgery. In this randomized, double-blind, placebo-controlled study, 124 children, ages 1–10 yr, received midazolam, 0.25, 0.50, or 0.75 mg·kg−1po, and atropine, 0.03 mg·kg−1po, mixed with apple juice, or a placebo (containing the midazolam vehicle, atropine, and apple juice). A blinded observer noted the child's level of sedation, the quality of separation from parents, and the degree of cooperation with an inhalation induction of anesthesia. Picture-recall was used to assess the amnesic effect of midazolam in children over 5 yr of age. Midazolam 0.75 mg·kg−1produced significant sedation at 30 min. After procedures lasting an average of 106–113 min, recovery was not prolonged by the oral midazolam-atropine combination. We concluded that oral midazolam 0.5–0.75 mg·kg−1is an effective preanesthetic medication for pediatric outpatients.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors conducted a randomized controlled clinical trial to evaluate the usefulness of perioperative manual evaluation of the response to train-of-four (TOF) nerve stimulation. A total of 80 patients were divided into four groups of 20 each. For two groups (one given vecuronium and one pancuronium), the anesthetists assessed the degree of neuromuscular blockade during operation and during recovery from neuromuscular blockade by manual evaluation of the response to TOF nerve stimulation. In the other two groups, one of which received vecuronium and the other pancuronium, the anesthetists evaluated the degree of neuromuscular blockade solely by clinical criteria. The use of a nerve stimulator was found to have no effect on the dose of relaxant given during anesthesia, on the need for supplementary doses of anticholinesterase in the recovery room, on the time from end of surgery to end of anesthesia, or on the incidence of postoperative residual neuromuscular blockade evaluated clinically. The median (and range of) TOF ratios recorded in the recovery room were 0.75 (0.33–0.96) and 0.79 (0.10–0.97) in the vecuronium groups monitored with and without a nerve stimulator, respectively. These ratios were significantly higher than those found in the pancuronium groups, which were 0.66 (0.06–0.90) and 0.63 (0.29–0.95), respectively. However, no difference was found between the vecuronium and pancuronium groups in the number of patients showing clinical signs of residual neuromuscular blockade, as evaluated by the 5-s head-lift test. All patients with clinical signs of residual neuromuscular blockade had a TOF ratio < 0.70, but the majority of patients (71%) with a TOF ratio < 0.70 were able to sustain head-lift for 5 s. A correlation was found between the peripheral skin temperature and the TOF ratio. It is concluded that under the conditions of this study, no effect of perioperative tactile evaluation of the response to TOF nerve stimulation could be demonstrated. In the avoidance of residual neuromuscular blockade, the choice of relaxant was more decisive than was manual evaluation of the response to TOF nerve stimulation.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effect of cardiac sympathetic blockade by high thoracic epidural anesthesia (TEA) (T1-T6, bupivacaine) on the luminal diameter of normal and diseased portions of epicardial coronary arteries was determined by quantitative coronary angiography in patients (n = 27) with severe coronary artery disease (CAD). In a separate group of patients (n = 9) with severe CAD, the effects of TEA on coronary arterioles (resistance vessels) were studied, by measuring total and regional myocardial blood flow and metabolism with the retrograde coronary sinus thermodilution technique. At the stenotic segments, TEA induced an increase in luminal diameter from 1.34 ± 0.11 to 1.56 ± 0.13 mm (P< 0.002), but did not change the diameter of the nonstenotic segments (3.07 ± 0.13 to 2.99 ± 0.13 mm). In the second group of patients, TEA induced no changes in coronary perfusion pressure, total or regional myocardial blood flow, coronary venous oxygen content, coronary blood flow distribution, regional myocardial oxygen consumption, or lactate extraction or uptake. Two patients had chest pain in the control situation and had regional myocardial lactate production that was attenuated by TEA. We conclude that TEA may increase the diameter of stenotic epicardial coronary artery segments in patients with CAD without causing a dilation of coronary arterioles. These effects may be beneficial when high TEA is used to treat severe ischemic chest pain in patients at rest.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Epidurally administered clonidine has been reported to produce postoperative analgesia. To assess the efficacy, safety, and appropriate dose of epidural clonidine for post-cesarean section analgesia, we designed a double-blind, placebo-controlled study. Sixty women were randomly assigned to receive epidural administration of saline bolus followed by 24-h saline infusion, 400-μg clonidine bolus followed by 10 μg/h clonidine infusion, or 800-μg clonidine bolus followed by 20 μg/h clonidine infusion. Supplemental analgesia was provided with patient-controlled iv morphine. Compared to saline, both clonidine regimens produced analgesia, as measured by verbal pain scores and supplemental iv morphine use during the first 6 h after bolus injection. Time to first morphine use was similar for both clonidine groups and significantly greater than saline. However, compared to saline, only the 20 μg/h clonidine infusion resulted in decreased morphine usage over the entire 24-h period. Compared to saline, both clonidine doses decreased blood pressure. This decrease was greater in the 400-μg than in the 800-μg clonidine group, but no patient required treatment for hypotension. Clonidine decreased heart rate (one patient required atropine for asymptomatic bradycardia) and produced transient sedation. The 800-μg clonidine dose prolonged resolution of local anesthetic-induced motor blockade compared to saline. These results suggest that epidurally administered clonidine provides analgesia, as measured by decreased need for supplemental morphine, after cesarean section, but continuous infusion is required for analgesia of more than 6 h duration.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of clonidine added to lidocaine solution used for epidural anesthesia were assessed in 92 women scheduled for surgery and premedicated with diazepam 10 mg po. Patients received 18 ml 2% lidocaine with clonidine 5 μg·ml−1(group C-5, n = 26), with clonidine 10 μg·ml−1(group C-10, n = 20), with epinephrine 5 μg·ml−1(group E, n = 26), or plain (group P, n = 20). No significant difference in the number of segments of analgesia was found at any observation period among the four groups of patients. The decreases in mean blood pressure (BP) observed 20 min after epidural injection in those given clonidine (5 ± 8% for C-5, 10 ± 11% for C-10, mean ± SD) were similar to those given plain lidocaine (7 ± 12%) but significantly less than those given epinephrine (18 ± 12%, P < 0.01 vs. C-5 or P). The response of BP to ephedrine given for restoring BP during anesthesia was not attenuated in patients who received epidural clonidine. Heart rate (HR) decreased significantly in patients given clonidine 10 μg·ml−1(7 ± 8%, P < 0.01), but not in those given clonidine 5 μg·ml−1, whereas HR increased significantly in those given lidocaine plain or with epinephrine (10 ± 8% and 28 ± 14%, respectively,P< 0.01). The incidence of sinus bradycardia was similar among the four groups of patients. Significant differences were also observed in sedation score between clonidine groups and groups P or E; sedation appeared approximately 10–20 min after epidural injection in both clonidine groups. Although respiratory rate, Pao2, and Paco2did not change after epidural injection in both clonidine groups, Pao2increased significantly (P< 0.01) in those given lidocaine plain or with epinephrine. Maximal plasma lidocaine concentrations (10–15 min after epidural injection) in group C-5 (n = 7,3.4 ± 0.2 μg·ml−1) and in group C-10 (n = 7, 3.6 ± 1.0 μg·ml−1) were comparable to those in group P (n = 7, 2.9 ± 1.0 μg·ml−1) but were significantly greater (P< 0.05) than those in group E (n = 7, 2.3 ± 0.4 μg·ml−1). These results indicate that the addition of clonidine to lidocaine for epidural anesthesia provides a sedative effect and relatively stable hemodynamics, and that clonidine in a concentration of 1:200,000 or 1:100,000, in contrast to 1:200,000 epinephrine, tends to increase rather than to suppress the plasma lidocaine concentrations. The latter effect may be related to altered metabolism of lidocaine by clonidine.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID