ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Little information is available about the incidence of severe adverse outcomes, and even less information is available about the identification and quantification of independent predictors of severe perioperative adverse outcomes. The purpose of this study was to identify and quantitate independent predictors of severe perioperative adverse outcomes in a prospective randomized clinical trial of general anesthesia in 17,201 patients. Twenty-nine prognostic variables for 15 severe outcomes in 847 patients were tested by multiple stepwise logistic regressions from which 20 significant (P< 0.05) predictors were identified. A history of cardiac failure or myocardial infarction ≤ 1 yr; ASA physical status 3 or 4; age > 50 yr; cardiovascular, thoracic, abdominal or neurologic surgery; and the study anesthetics were significant predictors of “any severe outcome, including death.” There were 17 significant predictors for 10 severe cardiovascular outcomes in 608 patients, including a history of ventricular arrhythmia, hypertension, cardiac failure, myocardial ischemia, myocardial infarction ≤ 1 yr or myocardial infarction > 1 yr, and smoking; ASA physical status; age; cardiovascular, thoracic, abdominal, eyes-ears-nose-throat/endocrine, neurologic, musculoskeletal, or gynecologic surgery; and the study anesthetics. There were 9 significant predictors for 4 severe respiratory outcomes in 163 patients, including a history of cardiac failure, myocardial ischemia, or chronic obstructive pulmonary disease; obesity; smoking; male gender; ASA physical status; abdominal surgery; and the study anesthetics. Colinearity between related prognostic variables (such as disease and ASA physical status) was assessed using progressively segregated groups of variables in eight stepwise logistic regressions. We conclude that the comprehensive stepwise logistic regression of 29 prognostic variables reported here provides a valid estimate of the risks of severe perioperative outcomes associated with general anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The most commonly used laboratory test for predicting malignant hyperthermia susceptibility is the caffeine halothane contracture test. However, the specificity and sensitivity of proposed North American diagnostic guidelines for this test have never been evaluated in a large, human study population. Therefore, the authors conducted a multiinstitutional, prospective study of skeletal muscle contracture responses in a subject population at low risk for malignant hyperthermia susceptibility to help determine the specificity of the proposed guidelines. Subjects were selected arbitrarily from a population of patients undergoing surgery unrelated to performance of a diagnostic muscle biopsy. Subjects were admitted to this study and were presumed nonsusceptible if there was no evidence of any of the following malignant hyperthermia risk factors: prior abnormal response to triggering anesthetic agents, myopathy, or family history of malignant hyperthermia susceptibility. The authors suggested rejection of the proposed diagnostic guidelines if an 85% specificity estimate among subjects could not be obtained. The authors analyzed the responses of 1,022 muscle fascicles, derived from 176 subjects, to the following: 1) separate administration of 3% halothane or incremental caffeine concentrations, or 2) the joint administration of 1 % halothane and incremental caffeine concentrations. The following contracture results were obtained. First, for individual fascicles, 9.2% exceeded a > 0.7 g threshold for 3% halothane, 15.2% exceeded a ≥ 0.2 g threshold for 2 mM caffeine, 32.4% exceeded a 1-g increase for < 4 mM caffeine, 2.6% had a > 7% maximal increase in tension at 2 mM caffeine, and 63.5% had a “halothane caffeine-specific concentration” at ≤ 1 mM caffeine. Second, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold were as follows: 45.8% for the four-component, 28.8% for the three-component, and 32.7% for the two-component contracture test. Third, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold for both halothane and caffeine were as follows: 9.5% for 3% halothane and 2 mM caffeine, 2.0% for 3% halothane and 7% maximal increase in tension at 2 mM caffeine, and 11.0% for 1% halothane and 2 mM caffeine. Fourth, center-to-center differences were the major source of variation in the rate that subjects exceeded proposed thresholds. These data demonstrate that proposed diagnostic guidelines must be modified to improve specificity estimates before adoption by diagnostic centers. The authors recommend efforts to develop a uniform method for analyzingin vivoadverse patient responses to anesthetics and to define contracturesensitivityfor the patient population susceptible to malignant hyperthermia.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The authors sought to define a dose of oral ketamine that would facilitate induction of anesthesia without causing significant side effects. Forty-five children (ASA Physical Status 1 and 2; aged 1–7 yr) were assigned randomly in a prospective, double-blind fashion to three separate groups that received either 3 mg/kg, 6 mg/kg, or no ketamine mixed in 0.2 ml/kg cola-flavored soft drink. They also were evaluated preoperatively and postoperatively for acceptance of oral ketamine as a premedicant, reaction to separation from parents, emotional state, and emergence phenomena. The authors detected no episodes of respiratory depression, tachycardia, or arterial hemoglobin desaturation before, during, or after surgery. The 6 mg/kg dose was well accepted; provided uniform, predictable sedation within 20–25 min; and allowed calm separation from parents and good induction conditions. The 3 mg/kg dose did not always cause sedation and calm separation from parents. Neither dose of ketamine increased the incidence of laryngospasm, prolonged recovery times, or caused emergence phenomena. The authors conclude that an oral dose of 6 mg/kg ketamine is easily administered and well accepted in young children and provides predictable, satisfactory premedication without significant side effects.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The authors evaluated train-of-four (TOF) fade, as quantified by accelography, in response to neurostimulation at currents ranging from 10 to 60 mA. This was done to determine the range of currents over which measurements of fade remain consistent. In 31 patients (ASA Physical Status 1, 2, and 3), anesthesia was induced with fentanyl, midazolam, and thiopental and was maintained with isoflurane and 66% nitrous oxide in oxygen. Surface stimulating electrodes were placed over the ulnar nerve, and an acceleration transducer was placed on the thumb. Succinylcholine was administered to facilitate tracheal intubation; after neuromuscular recovery, a bolus of vecuronium (0.01–0.05 mg.kg-1) and an infusion (0.25–1.5 μg.kg-1. min-1) were administered. After documentation of a stable TOF ratio, accelographic TOF responses were quantified in response to 200-μs stimulation at 10, 15, 20, 30, 40, 50, and 60 mA, in random order. A total of 95 data sets were collected at different depths of blockade. The TOF ratios maintained intercurrent consistency (P= not significant by nonparametric repeated measures analysis of variance), except at currents near the fourth-twitch (T4) threshold current. This inconsistency was eliminated by testing at ≥ 10 mA above threshold. TOF ratios obtained at 10 mA above T4threshold correlated highly with those at 60 mA (Spearman r value = 0.94). The authors conclude that the TOF ratio is consistent over a wide range of stimulating currents and that testing with submaximal currents can be performed reliably at ≥ 10 mA above theT4threshold.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Acute hypertensive responses during nitrous oxide-opioid-relaxant anesthesia are a common clinical problem. In adult men undergoing radical prostatectomy procedures and anesthetized with a standardized technique, we evaluated the effectiveness of alfentanil, isoflurane, and trimethaphan in treating acute hemodynamic and stress hormone responses to surgical stimulation. Stress hormone concentrations were measured 1 min before skin incision, after the onset of an acute hypertensive response, and after returning the mean arterial pressure to within 10% of the preincision values with one of the three treatment modalities. Pretreatment plasma alfentanil concentrations (151 ± 47 to 156 ± 47 ng. ml-1) and end-tidal nitrous oxide concentrations (66 ± 2 to 68 ± 2%) were similar in all three groups. Acute hypertensive events were associated with significantly increased concentrations of catecholamines and vasopressin (anti-diuretic hormone [ADH]). Whereas intravenous alfentanil returned all hormone concentrations to preincision values, norepinephrine and glucose concentrations were significantly increased after adjunctive isoflurane administration. Although trimethaphan decreased the norepinephrine concentration, the epinephrine,β-endorphin, cortisol, ADH, and glucose concentrations were significantly increased compared to preincision values. However, the persistent elevation in the posttreatment ADH concentration in the trimethaphan group was the only significant difference between the three groups. Mean (± standard deviation) times to awakening (2.8 ± 3.3 to 3.8 ± 4.2 min), extubation (8.1 ± 4.8 to 10.3 ± 8.5 min), and orientation (19.6 ± 20.4 to 24.6 ± 19.1 min) were similar in all three groups. Naloxone was required more frequently in patients in the alfentanil (35%) and isoflurane (24%) groups than in the trimethaphan group (4%). However, fewer alfentanil-treated patients required antihypertensive therapy in the postanesthesia care unit (12%vs.48% and 38% in the isoflurane and trimethaphan groups, respectively). Postoperative analgesic requirements and hospital discharge times were similar in all three groups. We conclude that the choice of adjunctive therapy to maintain hemodynamic stability during balanced anesthesia did not appear to effect outcome after radical prostatectomy procedures.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The safety and efficacy of oral transmucosal fentanyl citrate (OTFC) as a preanesthetic medication and the efficacy of droperidol as a prophylactic anti-emetic were evaluated in 100 children aged 2–8 yr undergoing general anesthesia for outpatient surgery. Patients were randomly assigned to one of four groups and managed in a double-blinded manner: 1) placebo lozenge 45 min preoperatively and placebo (normal saline) injected intravenously after induction of anesthesia; 2) placebo lozenge 45 min preoperatively and 50 μg/kg droperidol intravenously after induction; 3) 15–20 μg/kg OTFC lozenge 45 min preoperatively and placebo intravenously after induction; and 4) 15–20 μg/kg OTFC lozenge 45 min preoperatively and droperidol 50 μg/kg intravenously after induction. Anesthesia was induced and maintained with halothane and nitrous oxide in oxygen. Heart rate, respiratory rate, blood pressure, and hemoglobin oxygen saturation (Spo2) were monitored throughout the study. Scoring systems were used to evaluate sedation, anxiety, cooperation, and ease and quality of anesthetic induction. Emergence, recovery, and discharge times were recorded. Nausea, vomiting, and adverse effects were noted. Preoperatively, children receiving OTFC had significantly greater sedation, slower respiratory rates, lower Spo2, and less excitement during induction. Postoperative nausea and vomiting occurred significantly more frequently after OTFC than after placebo. Prophylactic droperidol did not significantly reduce the incidence of nausea and vomiting. The authors conclude that, in pediatric surgical outpatients, OTFC reliably induces preoperative sedation and facilitates inhalation induction of anesthesia, but it is associated with significant decreases in respiratory rate and Spo2and a high incidence of postoperative nausea and vomiting that is not significantly reduced by prophylactic droperidol.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Opioids are known to affect the MAC of inhalational anesthetics. We have determined the interaction between fentanyl and desflurane, following a bolus injection of fentanyl at induction in 134 adult patients. Five groups of patients were studied. Four groups received desflurane or isoflurane in oxygen with either fentanyl 3 or 6 μg/kg and thiopental 2–5 mg/kg given as a bolus injection at the time of induction. An additional group received desflurane in oxygen alone. Groups were stratified by age. MAC determination, in response to the stimulus of skin incision, was made using the “up-down'' method and logistic regression. The MAC of desflurane in oxygen was 6.3% (5.3–7.6%, 95% confidence interval [CI]). Fentanyl 3 μg/kg produced a fentanyl plasma concentration of 0.78 ± 0.53 ng/ml at skin incision and resulted in a MAC for desflurane of 2.6% (2.0–3.2%, 95% CI)%. Fentanyl 6 μg/kg produced a fentanyl plasma concentration of 1.72 ± 0.76 ng/ml at skin incision and resulted in a MAC for desflurane of 2.1% (1.5–2.6%, 95% CI). To compare recovery times to eye-opening and response to commands, patients were grouped according to the plasma fentanyl concentrations at the time of awaking. Recovery was faster in patients who received desflurane than in those who received isoflurane. The authors conclude that the MAC of desflurane is significantly reduced 25 min following a single dose of 3 μg/kg of fentanyl and that increasing the fentanyl dose to 6 μg/kg produces little further decrease in MAC. Desflurane is also associated with faster recovery from anesthesia than is isoflurane.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The increased metabolic and respiratory demand during naloxone recovery from opioid-based anesthesia could be related to the return of thermoregulation in hypothermic patients and thus be avoided by preventing intraoperative hypothermia. In this study, we measured O2uptake (Vo2) during naloxone-induced recovery in two groups of patients to determine the effect of intraoperative heat loss on postoperative Vo2changes. In seven patients, intraoperative hypothermia was prevented (normothermic group), whereas hypothermia was allowed to develop in seven other patients (hypothermic group). Core and skin temperatures were measured throughout the study to calculate changes in body heat content. Before naloxone antagonism of fentanyl-supplemented anesthesia, core temperature (mean ± SEM) was 36.8 ± 0.1° C in the normothermic group and 34.2 ± 0.2° C in the hypothermic group (P< 0.001). After titrated administration of naloxone during recovery, Vo2and minute ventilation (VE) increased in the hypothermic group, by 114 ± 37% and 97 ± 52% respectively (P< 0.05), with a three-fold increase in four patients. In the normothermic group, Vo2increased significantly less (25 ± 5%), without any significant change in VE. The change in Vo2and VEwas significantly greater in patients who were hypothermic. Vo2was integrated throughout the recovery period to calculate recovery energy expenditure. Recovery energy expenditure and intraoperative heat loss were highly correlated (r = 0.88;P< 0.01). This study demonstrates that the metabolic and respiratory stresses associated with naloxone-induced recovery from opioid-based anesthesia depend on the intraoperative heat loss and can therefore be reduced by preventing intraoperative hypothermia.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The role of protein binding in relation to the pharmacodynamics of alfentanil was investigated in 15 female and 13 male patients, aged 21–85 yr, ASA physical status 1 or 2, undergoing upper abdominal surgery. All patients had normal cardiac, hepatic, renal, and pulmonary function. None was receiving medication or had a history of alcohol or other drug abuse. Anesthesia was induced and maintained with 66% nitrous oxide in oxygen and alfentanil. Alfentanil was administered by a computer-controlled infusion pump. If, during surgery, the patient exhibited signs of inadequate anesthesia (i.e., response), the target alfentanil plasma concentration was increased by 50–100 ng/ml. If there was no response during a 15–min period, the target concentration was decreased by 50–100 ng/ml. Arterial blood samples were taken before any change of the target concentration and 4 min after the computer had indicated that the new target concentration had been reached. In addition, blood samples were taken before intubation, skin incision, and in the patients in whom ventilation recovered spontaneously before extubation. In the remaining patients a blood sample was taken before the administration of naloxone. Plasma alfentanil concentrations were determined by capillary gas chromatography. Alfentanil protein binding was determined by equilibrium dialysis in an arterial blood sample taken before induction of anesthesia. Alfentanil concentration-effect data were evaluated by logistic regression, where effect was either response or no response to perioperative stimuli. The average free fraction of alfentanil was 9.3 ± 3.9% (range 3.7–19.1%). For intubation, skin incision, and postanesthesia ventilation, it was not possible to characterize the concentration-effect curves based on total plasma concentrations with logistic regression. However, adequate logistic regression characterization for intubation and skin incision could be obtained using the unbound concentrations. For the intraabdominal component of surgery the average total plasma concentration for which the probability of no response during surgery is 50% (Cp50 total) was 476 ± 160 ng/ml (range 134–852 ng/ml). There was a significant negative correlation between Cp50 totaland free fraction (r = –0.67,P< 0.001). There was no correlation between either Cp50 totalor free fraction and age. The results of this study indicate that 45% (r2= 0.45) of the observed variability in the Cp50 totalof alfentanil could be explained by variability in the protein binding of alfentanil.

ISSN:0003-3022    

出版商:OVID    

年代:1992

数据来源: OVID