Showing papers in "Anesthesiology in 1998"
1,435 citations
TL;DR: It is demonstrated that method of administration (bolus vs. infusion), but not EDTA, influences the pharmacokinetics of propofol, and within the clinically relevant range, the kinetics of Propofol during infusions are linear regarding infusion rate.
Abstract: Background: Unresolved issues with propofol include whether the pharmacokinetics are linear with dose, are influenced by method of administration (bolus vs. infusion), or are influenced by age. Recently, a new formulation of propofol emulsion, containing disodium edetate (EDTA), was introduced in the United States. Addition of EDTA was found by the manufacturer to significantly reduce bacterial growth. This study investigated the influences of method of administration, infusion rate, patient covariates, and EDTA on the pharmacokinetics of propofol.
1,058 citations
683 citations
TL;DR: Lipid infusion shifts the dose‐response to bupivacaine‐induced asystole in rats and suggests a potential application for lipid infusion in treating cardiotoxicity resulting from bupvacaine.
Abstract: BackgroundThe authors sought to confirm a chance observation that intravenous lipid treatment increases the dose of bupivacaine required to produce asystole in rats. The authors also measured the partitioning of bupivacaine between the lipid and aqueous phases of a plasma-lipid emulsion mixture.Meth
629 citations
TL;DR: Perioperative administration of atenolol for 1 week to patients at high risk for coronary artery disease significantly reduces the incidence of postoperative myocardial ischemia.
Abstract: BackgroundPerioperative myocardial ischemia occurs in 20–40% of patients at risk for cardiac complications and is associated with a ninefold increase in risk for perioperative cardiac death, myocardial infarction, or unstable angina, and a twofold long-term risk. Perioperative atenolol administratio
525 citations
TL;DR: The dDown component of the systolic pressure variation is a sensitive indicator of the response of cardiac output to volume infusion in patient with sepsis‐induced hypotension who require mechanical ventilation.
Abstract: BackgroundMonitoring left ventricular preload is critical to achieve adequate fluid resuscitation in patients with hypotension and sepsis. This prospective study tested the correlation of the pulmonary artery occlusion pressure, the left ventricular end-diastolic area index measured by transesophage
523 citations
TL;DR: The rating system needs more refinement before it can be used to assess clinical competence for residency graduation or board certification, and behavioral performance can be assessed from videotapes of simulations.
Abstract: BackgroundTechniques are needed to assess anesthesiologists' performance when responding to critical events. Patient simulators allow presentation of similar crisis situations to different clinicians. This study evaluated ratings of performance, and the interrater variability of the ratings, made by
498 citations
TL;DR: Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) and hemostatic blood components and for patients at institutions with liberal rather than conservative transfusions practice.
Abstract: Background An estimated 20% of allogeneic blood transfusions in the United States are associated with cardiac surgery. National consensus guidelines for allogeneic transfusion associated with coronary artery bypass graft (CABG) surgery have existed since the mid- to late 1980s. The appropriateness and uniformity of institutional transfusion practice was questioned in 1991. An assessment of current transfusion practice patterns was warranted. Methods The Multicenter Study of Perioperative Ischemia database consists of comprehensive information on the course of surgery in 2,417 randomly selected patients undergoing CABG surgery at 24 institutions. A subset of 713 patients expected to be at low risk for transfusion was examined. Allogeneic transfusion was evaluated across institutions. Institution as an independent risk factor for allogeneic transfusion was determined in a multivariable model. Results Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) (27-92% of patients transfused) and hemostatic blood components (platelets, 0-36%; fresh frozen plasma, 0-36%; cryoprecipitate, 0-17% of patients transfused). For patients at institutions with liberal rather than conservative transfusion practice, the odds ratio for transfusion of PRBCs was 6.5 (95% confidence interval [CI], 3.8-10.8) and for hemostatic blood components it was 2 (95% CI, 1.2-3.4). Institution was an independent determinant of transfusion risk associated with CABG surgery. Conclusions Institutions continue to vary significantly in their transfusion practices for CABG surgery. A more rational and conservative approach to transfusion practice at the institutional level is warranted.
410 citations
TL;DR: It is determined that PMI was an early event, only occasionally associated with chest pain, and usually non‐Q wave in nature, in a large group of patients at risk for postoperative myocardial infarction.
Abstract: Background: In this study, the authors intensively monitored isoenzyme and electric activity of the heart for the first 7 days after noncardiac surgery in a large group of patients at risk for postoperative myocardial infarction (PMI). Metbods: After institutional review board approval and written informed consent were received, 323 patients, aged 50 yr or older, who had ischemic heart disease and presented for noncardiac surgery, were enrolled in this prospective, blinded study. After operation, patients had daily clinical assessments, electrocardiograms, and measurements of creatine kinase (CK), CK-2 (mass and activity), and Troponin-T on the operative night, twice daily on postoperative days 1-4, and then daily on days 5-7. A diagnosis of PMI was made if the total CK was >174 U/I and in the presence of two of the following: (1) CK-2/CK (mass or activity) >5%, (2) new Q waves lasting ≥0.04 s and 1 mm deep in at least two contiguous leads, (3) Troponin-T was >0.2 μg/1, or (4) a positive result of pyrophosphate scan. Results: Eighteen of the 323 patients (5.6%) had a PMI, of which 3 (17%) were fatal. Only 3 of 18 patients had chest pain, whereas 10 of 18 patients (56%) had other clinical findings. The electrocardiographic classification of the PMI was Q wave in 6, non-Q wave in 10, and indeterminate in 2. The PMIs occurred on the day of operation in 8, on day one in 6, on day two in 3, and on day four in 1 patient. Conclusions: This study determined that PMI was an early event, only occasionally associated with chest pain, and usually non-Q wave in nature.
400 citations
TL;DR: Oral midazolam is more effective than either parental presence or no intervention for managing a child's and parent's anxiety during the preoperative period.
Abstract: BackgroundBoth midazolam and parental presence during induction of anesthesia are routinely used to treat preoperative anxiety in children. The purpose of this investigation was to determine which of these two interventions is more effective.MethodsAnxiety of the child during the perioperative perio
375 citations
TL;DR: In this article, the authors evaluated the accuracy of three EEG parameters and anesthetic concentration for predicting the depth of seda in the presence of anesthetic in the EEG signal, and the results showed that the EEG parameters were more accurate than the anesthetic concentrations.
Abstract: BackgroundThe electroencephalogram (EEG) has been evaluated as a tool for measuring depth of anesthesia, but the use of the EEG monitoring is still controversial. The current study was designed to evaluate the accuracy of three EEG parameters and anesthetic concentration for predicting depth of seda
TL;DR: Subanesthetic doses of ketamine produce psychedelic effects in healthy volunteers and the relation between steady‐state venous plasma ketamine concentrations and effects is highly linear between 50 and 200 ng/ml.
Abstract: Background: Ketamine has been associated with a unique spectrum of subjective psychedelic effects in patients emerging from anesthesia. This study quantified these effects of ketamine and related them to steady-state plasma concentrations. Methods : Ketamine or saline was administered in a single-blinded crossover protocol to 10 psychiatrically healthy volunteers using computer-assisted continuous infusion. A stepwise series of target plasma concentrations, 0, 50, 100, 150, and 200 ng/ml were maintained for 30 min each. After 20 min at each step, the volunteers completed a visual analog (VAS) rating of 13 symptom scales. Peripheral venous plasma ketamine concentrations were determined after 28 min at each step. One hour after discontinuation of the infusion, a psychological inventory, the hallucinogen rating scale, was completed. Results: The relation of mean ketamine plasma concentrations to the target concentrations was highly linear, with a correlation coefficient of R = 0.997 (P = 0.0027). Ketamine produced dose-related psychedelic effects. The relation between steady-state ketamine plasma concentration and VAS scores was highly linear for all VAS items, with linear regression coefficients ranging from R = 0.93 to 0.99 (P < 0.024 to P < 0.0005). Hallucinogen rating scale scores were similar to those found in a previous study with psychedelic doses of N,N-dimethyltryptamine, an illicit LSD-25-like drug. Conclusions: Subanesthetic doses of ketamine produce psychedelic effects in healthy volunteers. The relation between steady-state venous plasma ketamine concentrations and effects is highly linear between 50 and 200 ng/ml.
TL;DR: Bispectral index accurately predicts response to verbal commands during sedation and hypnosis with propofol or prop ofol plus nitrous oxide and provided additional predictive power when combined with treatment history.
Abstract: BackgroundThe bispectral index (BIS) measures changes in the interfrequency coupling of the electroencephalogram (EEG). The purposes of this study were (1) to determine whether BIS correlates with responses to command during sedation and hypnosis induced by propofol or propofol and nitrous oxide, an
TL;DR: Among other factors postulated to increase risk, obesity had an effect of borderline statistical significance, whereas age, sex, history of back pain, needle type, and lidocaine dose and concentration failed to affect risk.
Abstract: BackgroundRecent evidence suggests that transient neurologic symptoms commonly follow lidocaine spinal anesthesia. However, information concerning factors that affect their occurrence is limited. Accordingly, to evaluate many potential risk factors, the authors undertook a prospective, multicenter,
TL;DR: Maternal sedation and respiratory changes occur, but without adverse neonatal or maternal effects, and remifentanil crosses the placenta but appears to be rapidly metabolized, redistributed, or both.
Abstract: Background Remifentanil has not been studied in obstetric patients. This study evaluates the placental transfer of remifentanil and the neonatal effects when administered as an intravenous infusion. Methods Nineteen parturients underwent nonemergent cesarean section with epidural anesthesia and received 0.1 microg kg(-1) x min(-1) remifentanil intravenously, which was continued until skin closure. Maternal arterial (MA), umbilical arterial (UA), and umbilical venous (UV) blood samples were obtained at delivery for analysis of drug concentrations of remifentanil, its metabolite, and blood gases. Maternal vital signs were monitored continuously, and pain and sedation levels were assessed intermittently. Apgar scores were obtained at 1, 5, 10, and 20 min, and Neonatal and Adaptive Capacity Scores were noted 30 and 60 min after delivery. Parturients and newborns were observed for at least 24 h after surgery for side effects. Results The means and SDs of UV:MA and UA:UV ratios for remifentanil were 0.88+/-0.78 and 0.29+/-0.07, respectively. Mean clearance was 93 ml x min(-1) kg(-1). The mean UV:MA and UA:MV ratios for remifentanil acid were 0.56+/-0.29 and 1.23+/-0.89, respectively. The mean MA (remifentanil acid):MA (remifentanil) ratio was 2.92+/-3.65. There were no adverse effects on the neonates, but there was a sedative effect and respiratory depressant effect on the mothers. Conclusions Remifentanil crosses the placenta but appears to be rapidly metabolized, redistributed, or both. Maternal sedation and respiratory changes occur, but without adverse neonatal or maternal effects.
TL;DR: Clinically this means that remifentanil dosing regimens should be based on ideal body weight (or LBM) and not TBW, and that the pharmacokinetic parameters are therefore more closely related to LBM than to TBW.
Abstract: Background Remifentanil is a short-acting opioid whose pharmacokinetics have been characterized in detail. However, the impact of obesity on remifentanil pharmacokinetics has not been specifically examined. The goal of this study was to investigate the influence of body weight on remifentanil pharmacokinetics. Methods Twelve obese and 12 matched lean subjects undergoing elective surgery received a 1-min remifentanil infusion after induction of anesthesia. Arterial blood samples were collected for determination of remifentanil blood concentrations. Each subject's pharmacokinetic parameters were estimated by fitting a two-compartment model to the concentration versus time curves. Nonlinear mixed-effects population models examining the influence of lean body mass (LBM) and total body weight (TBW) were also constructed. Clinical simulations using the final population model were performed. Results The obese patient cohort reached substantially higher remifentanil concentrations. The individual pharmacokinetic parameters of a two-compartment model were not significantly different between the obese versus lean cohorts (unless normalized to TBW). The final population model scaled central clearance and the central and peripheral distribution volumes to LBM. The simulations illustrated that remifentanil pharmacokinetics are not grossly different in obese versus lean subjects and that TBW based dosing in obese patients can result in excessively high remifentanil concentrations. Conclusions The essential findings of the study are that remifentanil's pharmacokinetics are not appreciably different in obese versus lean subjects and that remifentanil pharmacokinetic parameters are therefore more closely related to LBM than to TBW. Clinically this means that remifentanil dosing regimens should be based on ideal body weight (or LBM) and not TBW.
TL;DR: Use of intraoperative music in awake patients decreases patient‐controlled sedative and analgesic requirements, which could be caused by elimination of ambient operating room noise and not by the effects of music.
Abstract: BackgroundTo determine whether music influences intraoperative sedative and analgesic requirements, two randomized controlled trials were performed.MethodsIn phase 1, 35 adults undergoing urologic procedures with spinal anesthesia and patient-controlled intravenous propofol sedation were randomly as
TL;DR: Variability in lumbosacral CSF volume is the most important factor identified to date that contributes to the variability in the spread of spinal sensory anesthesia.
Abstract: BackgroundInjection of local anesthetic into cerebrospinal fluid (CSF) produces anesthesia of unpredictable extent and duration. Although many factors have been identified that affect the extent of spinal anesthesia, correlations are relatively poor and the extent of spread remains unpredictable. Th
TL;DR: Mild perioperative hypothermia suppressed mitogen‐induced activation of lymphocytes and reduced the production of certain cytokines, IL‐1 [small beta, Greek] and IL‐2, and in this way may contribute to the immune alterations observed in the peri operative period.
Abstract: Background Unintentional perioperative hypothermia is a common complication of anesthesia and surgery associated with adverse effects on several systems, including impaired wound healing and more frequent wound infections. Mild hypothermia affects various immune functions. In the current study, the authors sought to determine whether immune alterations in the perioperative period might be induced, at least in part, by impaired thermoregulation during this period. Methods Sixty patients undergoing abdominal surgery were randomly assigned to two thermal care groups: routine care or forced-air warming. The patients' anesthetic care was standardized. Venous blood samples were collected 90 min before induction of anesthesia and immediately, 24 h, and 48 h after surgery. White cells were separated and frozen. Peripheral blood mononuclear cells were used to test cytokine production (interleukins [IL] -1 [small beta, Greek], -2, and -6; tumor necrosis factor-[small alpha, Greek] [TNF-[small alpha, Greek]), mitogens-induced proliferation, and natural killer NK cell cytotoxicity. Plasma cortisol levels were also determined. Results Patients in the normothermia group maintained normal body core temperature, whereas temperature decreased by approximately 1 [degree sign]C in the hypothermia group. Mitogenic responses were suppressed in cells from patients in the hypothermia but not in the normothermia group 24 and 48 h after surgery. Proinflammatory cytokine (IL-1 [small beta, Greek], IL-6, TNF-[small alpha, Greek]) production increased in both groups, although the production of IL-1 [small beta, Greek] was significantly higher in the normothermia group 24 h after surgery. Production of IL-2 was suppressed in the hypothermia but not in the normothermia group at 24 h. Conclusions Mild perioperative hypothermia suppressed mitogen-induced activation of lymphocytes and reduced the production of certain cytokines, IL-1 [small beta, Greek] and IL-2, and in this way may contribute to the immune alterations observed in the perioperative period.
TL;DR: Although the spectral content of the EEG changed during N (2) O administration, reflecting some pharmacologic effect, the subjects remained cooperative and responsive throughout, and therefore N2 O can only be considered a weak sedative at the tested concentrations.
Abstract: BackgroundNitrous oxide (N2 O) is a commonly used sedative for painful diagnostic procedures and dental work. The authors sought to characterize the effects of N2 O on quantitative electroencephalographic (EEG) variables including the bispectral index (BIS), a quantitative parameter developed to cor
TL;DR: Routine bronchoscopy is recommended after intubation and after patient positioning for thoracic surgery to verify the position of double‐lumen tubes (DLT), because more than one third of DLTs required repositioning.
Abstract: Background Fiberoptic bronchoscopy has been recommended to verify the position of double-lumen tubes (DLT), but this remains controversial. The authors studied the role of bronchoscopy for placing and monitoring right- and left-sided DLTs after blind intubation and after positioning the patient. Methods Two hundred patients having thoracic surgery requiring DLT insertion were prospectively studied. "Blind" tracheal intubations were done with 163 left-sided and 37 right-sided disposable polyvinyl chloride Robertshaw tubes. Bronchoscopy was performed by a different anesthesiologist after intubation and conventional clinical verification of correct placement and after patient positioning for thoracotomy. A DLT was considered malpositioned when it had to be moved >0.5 cm to correct its position. Critical malpositions were those that might have affected patient safety or influenced the surgical procedure if left uncorrected. Results After "blind" DLT intubation, clinical evidence of malpositioning was found in 28 patients. This was confirmed by fiberoptic assessment. In 172 patients in whom placement was judged correct by clinical assessment, malpositioning was detected by bronchoscopy in 79 cases, 25 of which were critical. After patient positioning, DLTs were found to be displaced in 93 patients, 48 of which were critical. Right-sided DLTs were significantly more likely to be malpositioned than were left-sided DLTs. Two complications were related to unsatisfactory lung separation in the 200 patients studied. Conclusions After blind intubation and patient positioning, more than one third of DLTs required repositioning. Routine bronchoscopy is therefore recommended after intubation and after patient positioning.
TL;DR: Pat‐controlled epidural analgesia provides effective and safe postoperative analgesia on hospital wards and reasons for termination were elective, displaced epidural catheter, infection, side effects, inadequate analgesia, and other.
Abstract: BackgroundThe efficacy and safety of patient-controlled yepidural analgesia (PCEA) for postoperative analgesia on hospital wards was studied.MethodsPostoperative analgesia was provided for 1,030 patients with PCEA using 0.05% bupivacaine and fentanyl, 4 micro gram/ml, in a standardized manner. Patie
TL;DR: The lower lipid solubility of ropivacaine may be responsible for the lesser dose‐dependent effects of this drug on mitochondrial bioenergetics.
Abstract: BackgroundHigh lipophilic local anesthetics interfere with mitochondrial energy metabolism. These metabolic effects could in part explain some of the toxic effects of local anesthetics, such as bupivacaine-induced myocardial depression. The aim of this study was to compare the bioenergetic effects o
TL;DR: Spinal anesthesia with lidocaine and with bupivacaine causes a clinically significant disturbance of bladder function due to interruption of the micturition reflex and bladder function remains impaired until the block has regressed to the third sacral segment in all patients.
Abstract: BackgroundThe aim of this study was to evaluate and compare the effects of spinal anesthesia with lidocaine and with bupivacaine on urinary bladder function in healthy men who were scheduled for minor orthopaedic surgical procedures.MethodsTwenty men were randomly allocated to receive either bupivac
TL;DR: Some EEG descriptors correlated linearly with the magnitude of the cerebral metabolic reduction caused by propofol and isoflurane anesthesia, suggesting that a physiologic link exists between the EEG and cerebral metabolism during anesthesia that is mathematically quantifiable.
Abstract: BackgroundTo help elucidate the relationship between anesthetic-induced changes in the electroencephalogram (EEG) and the concurrent cerebral metabolic changes caused by anesthesia, positron emission tomography data of cerebral metabolism obtained in volunteers during anesthesia were correlated retr
TL;DR: The authors report the results of their analysis of pooled data from the North American Malignant Hyperthermia Registry database to determine the sensitivity and specificity of the caffeine-halothane contracture test.
Abstract: BackgroundThe caffeine-halothane contracture test (CHCT) is the only recognized laboratory test to diagnose malignant hyperthermia (MH). The authors report the results of their analysis of pooled data from the North American Malignant Hyperthermia Registry database to determine the sensitivity and s
TL;DR: Large atelectasis in the dorsal part of the lungs was found on the first postoperative day after cardiac surgery, however, there was no clear correlation between atElectasis and measured shunt fraction.
Abstract: BackgroundSometimes a high intrapulmonary shunt occurs after cardiac surgery, and impairment of lung function and oxygenation can persist for 1 week after operation. Animal studies have shown that postoperative shunt can be explained by atelectasis. In this study the authors tried to determine if at
TL;DR: It is indicated that multiplane TEE can provide an alternative method for the intraoperative measurement of CO and the ability of the rotatable imaging array to align with the left ventricular outflow tract and the need for only minimal adjustments in probe position advance the utility of intraoperative TEE.
Abstract: Background Limitations in the imaging views that can be obtained with transesophageal echocardiography (TEE) have hindered development of a widely adopted Doppler method for cardiac output (CO) monitoring. The authors evaluated a CO technique that combines steerable continuous-wave Doppler with the imaging capabilities of two-dimensional multiplane TEE. Methods From the transverse plane transgastric, short-axis view of the left ventricle, the imaging array was rotated to view the left ventricular outflow tract (LVOT) and ascending aorta. Steerable continuous-wave Doppler was subsequently used to measure aortic blood flow velocities. Aortic valve area was determined using a triangular orifice model. Matched thermodilution and Doppler CO measurements were obtained serially during surgery. Results The left ventricular outflow tract was imaged in 32 of 33 patients (97%). Data analysis reveal a mean difference between techniques of -0.01 l/min, and a standard deviation of the differences of 0.56 l/min. Multiple regression showed a correlation of r = 0.98 between intrasubject changes in CO. Multiplane TEE correctly tracked the direction of 37 of 38 serial changes in thermodilution CO but with a modest 14% underestimation of the magnitude of these changes. Conclusions These results indicate that multiplane TEE can provide an alternative method for the intraoperative measurement of CO. The ability of the rotatable imaging array to align with the left ventricular outflow tract and the need for only minimal adjustments in probe position advance the utility of intraoperative TEE.