ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors attempted to simultaneously measure cardiac output by thermodilution (COtd), thoracic bioimpedance (CObi), and suprasternal Doppler ultrasound (COdopp) in 68 patients. Subgroups separately compared included patients whose lungs were mechanically ventilated, patients undergoing cardiac surgery, aortic surgery, patients with dysrhythmias, and patients with sepsis. The authors also studied the value of the ventricular ejection time (VET) in evaluating the agreement of CObiand COdoppwith COtd. Simultaneous CObiand COtdwere available in a total of 56 patients (416 data sets) with an overall correlation coefficient r = 0.61, regression slope (m) of 0.52, intercept (y) of 2.46, and mean (CObi— COtd) difference (bias) of −0.67 ± 1.72 (SD) 1/min. Simultaneous COdoppand COtdwere available in 59 patients (446 data sets) with an overall r = 0.51, m of 0.53, y of 2.05, and bias of −0.79 ± 1.95 1/min. CObiagreed most closely with COtdin patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and with VET difference < 40 ms (16 patients, 99 data sets; r = 0.74; m = 0.97; y = 0.15; bias = −0.02 ± 1.53 1/min). COdoppagreed most closely with COtdin patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and in sinus rhythm with VET difference < 40 ms (10 patients, 45 data sets; r = 0.82; m = 0.98; y = −0.07; bias = −0.82 ± 1.03 1/min). VET by radial artery can help evaluate the reliability of CObiand COdopp.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To determine the effect of prematurity on the solubility of volatile anesthetics in blood, the authors measured the blood/gas partition coefficients of sevoflurane, isoflurane, and halothane and the serum concentrations of albumin, globulin, cholesterol, and triglycerides in umbilical venous blood from ten preterm and eight full-term neonates and in venous blood from eight fasting adult volunteers. The authors found that the blood/gas partition coefficient of sevoflurane did not differ significantly among the three age groups. The partition coefficients of isoflurane and halothane in preterm neonates did not differ significantly from those in full-term neonates. However, the partition coefficients of both anesthetics in neonates were significantly less than those in adults. The blood/gas partition coefficients of the three volatile anesthetics in preterm neonates did not change significantly with gestational age. The blood/gas partition coefficients of sevoflurane, isoflurane and halothane for all three age groups combined correlated only with the serum concentration of cholesterol. The authors conclude that the blood/gas partition coefficients of isoflurane, halothane, and sevoflurane in preterm neonates are similar to those in full term neonates and that gestational age does not significantly affect the blood/gas solubility.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Ninety women undergoing gynecologic laparoscopy were randomly given clonidine 3 or 4.5 μg/kg or saline intramuscularly 45–60 min prior to induction of anesthesia. Anesthesia was induced with thiopental 3.5 mg/kg and maintained with 0.3% end-tidal isoflurane in nitrous oxide and oxygen. The laparoscopy did not begin sooner than 20 min after tracheal intubation. Arterial blood pressure and heart rate were monitored with an automatic oscillometer. When compared with the baseline values, clonidine 4.5 μg/kg significantly (P< 0.001) decreased the mean arterial pressure (MAP) measured before induction of anesthesia. In all three groups, blood pressure and heart rate increased after tracheal intubation and after beginning of laparoscopy (P< 0.001), but the increments were significantly greater in the control group than in the study groups. During anesthesia alone without surgical stimulation, and again in the recovery room, MAP and heart rate were lower in the study groups than in the control group. Plasma β-endorphin immunoreactivity (ir β-E) was measured for ten control-group women and ten women receiving clonidine 4.5 μg/kg before premedication, before and after induction of anesthesia, during laparoscopy, and 1 h after the procedure. The plasma ir β-E increased significantly after the beginning of laparoscopy in both the control group and those given clonidine, but the increase was significantly less (P< 0.05) in the women premedicated with clonidine. The blunting effect of clonidine on hemodynamics and plasma β endorphin may reflect a deeper level of anesthesia in those women receiving clonidine as preanesthetic medication or can be explained by an interaction of clonidine with endogenous opiates. The authors conclude that intramuscularly administered clonidine premedication effectively prevents the maximal hemodynamic responses to tracheal intubation and to gynecologic laparoscopy. Further clinical studies on the clinical importance of the role of clonidine preanesthetic medication are warranted.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

In order to evaluate reversal time from very intense neuromuscular blockade caused by a continuous infusion of atracurium, the time course of neostigmine induced reversal from different levels of neuromuscular blockade was evaluated using the post-tetanic count (PTC) and the train-of-four (TOF) in 30 patients anesthetized with nitrous oxide, fentanyl, and thiopental. Reversal time (time from administration of neostigmine at different PTC levels to a TOF ratio of 0.7) was found to depend upon the degree of blockade at the time of reversal. Median reversal time from a PTC of 1–2, 3–4, 5–6, 7–8, 9–10, 11–12, and >13 (but less than 10% twitch height) to a TOF ratio of 0.7 was 31, 23, 19, 18, 14, and 13 min, respectively. Spontaneous recovery from PTC level of 1–2, when atracurium infusion was stopped, to a PTC level at which antagonism was induced and reversal time were both correlated to the square root of the PTC. Total recovery time (spontaneous recovery plus reversal time) was not shortened by an early injection of neostigmine. It is concluded that neostigmine administration during intense neuromuscular blockade following atracurium infusion does not shorten total recovery time and offers no clinical advantages.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study aimed to determine whether: 1) the method of cooling the hand (i.e. central [total body] vs. local surface [hand only]) influences the relationship between the adductor pollicis temperature and twitch tension; and 2) decreased evoked twitch response during hypothermia is due to reduced muscle temperature and/or the anesthetic drug used. First, the effect of local surface cooling on adductor pollicis twitch tension during isoflurane anesthesia was determined in 15 patients, while central body temperature was not allowed to decrease. Adductor pollicis temperature and twitch tension decreased in a linear manner (P< 0.05). However, the magnitude of the decreased response was only 43% of that observed during central cooling in the authors' previous study under otherwise similar experimental conditions. Second, the effect of central cooling on adductor pollicis twitch tension during nitrous oxide/fentanyl anesthesia was determined in five patients. The twitch tension did not decrease until the adductor pollicis temperature decreased below 35.2° C. Below this temperature, twitch tension decreased 16%/° C reduction in muscle temperature. These results are similar to those obtained in the authors' previous study in patients anesthetized with nitrous oxide/isoflurane anesthesia. The authors conclude that both central and local surface cooling of the adductor pollicis muscle reduces twitch tension and that the decrease in adductor pollicis twitch tension is the same during nitrous oxide/isoflurane and nitrous oxide/fentanyl anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors retrospectively reviewed the charts of 36 pediatric patients who had undergone cardiac surgery with hypothermic cardiopulmonary bypass (CPB) (n = 24) or profound hypothermia with circulatory arrest (PHCA) (n = 12), none of whom had received dextrose in the clear CPB pump prime, maintenance iv fluids, or cardioplegia solution. The authors studied whether the doses of fentanyl or methylprednisolone, or rates of dextrose infusion from blood products during CPB or from vasoactive infusions in 5% dextrose in water, were correlated with the blood glucose concentrations at the termination of CPB. Because other investigations have indicated that even moderate hyperglycemia during cerebral hypoxia or ischemia may predispose patients to an increased risk of neurologic deficit, the authors wished to determine whether any of these factors might contribute significantly to the elevation in blood glucose commonly seen in these patients. Multiple regression analysis and ANOVA were performed on these data, and aPvalue of 0.0125 was considered significant. The dose of methylprednisolone, and rates of infusions of dextrose from blood products in the CPB pump prime or from 5% dextrose in water at the termination of CPB did not correlate significantly with the blood glucose level. The dose of fentanyl administered to patients prior to the end of CPB was significantly correlated with the glucose concentration (r2= 0.416;P= 0.0001). No patient who received ≥50 µg/kg of fentanyl had a blood glucose concentration of >200 mg/dl. This suggests that doses of fentanyl ≥ 50 µg/kg in conjunction with limiting exogenous dextrose infusion can attenuate the hyperglycemic response to hypothermic CPB and PHCA in children undergoing cardiac surgery.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The authors tested the hypotheses that during epidural anesthesia: 1) shivering-like tremor is primarily normal thermoregulatory shivering; 2) hypothermia does not produce a subjective sensation of cold; and 3) injectate temperature does not influence tremor intensity. An epidural catheter was inserted into ten healthy, nonpregnant volunteers randomly assigned to skin-surface warming below the T10 dermatome (warmed group) or no extra warming (unwarmed group). Each volunteer was given two 30-ml epidural injections of 1% lidocaine (16.0 ± 4.7° C and 40.6 ± 0.7° C at the catheter tip), in random order separated by at least 3 h. Skin-temperature gradients (forearm–fingertip) and tympanic membrane and average skin temperatures were recorded; significant vasoconstriction was prospectively defined as a gradient ≥ 4° C. Integrated electromyographic (EMG) intensity was recorded from four upper-body muscles. Overall thermal comfort was evaluated using a visual analog scale. Tympanic membrane temperatures decreased significantly in the unwarmed group (n = 6). Tremor occurred following ten of 12 injections in unwarmed volunteers, but only following one of eight injections in the warmed group. Integrated EMG intensity did not differ significantly following epidural injection of warm and cold lidocaine: tremor started when tympanic membrane temperature decreased about 0.5° C and continued until central temperature returned to within 0.5° C of control. Tremor always was preceded by hypothermia and vasoconstriction in the arms. Thermal comfort increased in both groups after epidural injection, with maximal comfort occurring at the lowest tympanic temperatures. These data suggest that: 1) tremor during epidural anesthesia is primarily normal thermoregulatory shivering; 2) epidural injectate temperature does not influence tremor intensity; and 3) central hypothermia does not necessarily produce a subjective sensation of cold.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study tested the hypothesis that the threshold for thermoregulatory vasoconstriction is lowered as isoflurane concentration increases, but that the intensity of vasoconstriction, once triggered, is well preserved during isoflurane anesthesia. The thermoregulatory threshold was prospectively defined as the central temperature at which vasoconstriction occurred, and significant vasoconstriction was defined as a skin-surface temperature gradient (forearm–fingertip) ≥ 4° C. The threshold for thermoregulatory vasoconstriction and the intensity of vasoconstriction, measured as maximum skin-temperature gradient, was determined in six unpremedicated patients electively donating a kidney during isoflurane anesthesia, and in four healthy, awake volunteers. All anesthetized patients were deliberately cooled and became hypothermia. Vasoconstriction occurred in five of six at central temperatures between 35.3 and 32.4° C, at end-tidal isoflurane concentrations between 0.74 and 1.65%. The patient who did not vasoconstrict received the highest isoflurane concentration (≈2.5%) and reached a central temperature of 31° C. Unanesthetized volunteers also were exposed to cold and each vasoconstricted at a temperature near 37° C. The threshold for thermoregulatory cutaneous vasoconstriction was inversely correlated with anesthetic dose, the thermoregulatory threshold decreasing ≈3 ° C/% isoflurane concentration. There were no statistically significant differences between maximum skin-surface temperature gradients in awake volunteers and patients given isoflurane, or between any of the groups when patients from previous studies given halothane or nitrous oxide/fentanyl anesthesia were included in the comparison. These data indicate that the intensity of vasoconstriction, once triggered, is similar during several different types of anesthesia. A high correlation between calf–toe and forearm–fingertip temperature gradients, and between esophageal and tympanic membrane temperatures, also was demonstrated.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Adverse outcomes associated with respiratory events constitute the single largest class of injury in the American Society of Anesthesiology Closed Claims Study (522 of 1541 cases; 34%). Death or brain damage occurred in 85% of cases. The median cost of settlement or jury award was $200,000. Most outcomes (72%) were considered preventable with better monitoring. Three mechanisms of injury accounted for three-fourths of the adverse respiratory events: inadequate ventilation (196; 38%), esophageal intubation (94; 18%), and difficult tracheal intubation (87; 17%). Inadequate ventilation was used to describe claims in which it was evident that insufficient gas exchange had produced the adverse outcome, but it was not possible to identify the exact cause. This group was characterized by the highest proportion of cases in which care was considered substandard (90%). The esophageal intubation group was notable for a recurring diagnostic failure: in 48% of cases where auscultation of breath sounds was performed and documented, this test led to the erroneous conclusion that the endotracheal tube was correctly located in the trachea. Claims for difficult tracheal intubation were distinguished by a comparatively small proportion of cases (36%) in which the outcome was considered preventable with better monitoring. A better understanding of respiratory risks may require investigative protocols that initiate data collection immediately upon the recognition of a critical incident or adverse outcome.

ISSN:0003-3022    

出版商:OVID    

年代:1990

数据来源: OVID