The effect of anesthetic technique on postoperative outcomes in hip fracture repair.

BACKGROUND: The impact of anesthetic choice on postoperative mortality and morbidity has not been determined with certainty. METHODS: The authors evaluated the effect of type of anesthesia on postoperative mortality and morbidity in a retrospective cohort study of consecutive hip fracture patients, aged 60 yr or older, who underwent surgical repair at 20 US hospitals between 1983 and 1993. The primary outcome was defined as death within 30 days of the operative procedure. The secondary outcomes were postoperative 7-day mortality, postoperative myocardial infarction, postoperative pneumonia, postoperative congestive heart failure, and postoperative change in mental status. Numerous comorbid conditions were controlled for individually and by several comorbidity indices using logistic regression. RESULTS: General anesthesia was used in 6,206 patients (65.8%) and regional anesthesia in 3,219 patients (3,078 spinal anesthesia and 141 epidural anesthesia). The 30-day mortality rate in the general anesthesia group was 4.4%, compared with 5.4% in the regional anesthesia group (unadjusted odds ratio = 0.80; 95% confidence interval = 0.66-0.97). However, the adjusted odds ratio for general anesthesia increased to 1.08 (0.84-1.38). The adjusted odds ratios for general anesthesia versus regional anesthesia for the 7-day mortality was 0.90 (0.59-1.39) and for postoperative morbidity outcomes were as follows: myocardial infarction: adjusted odds ratio = 1.17 (0.80-1.70); congestive heart failure: adjusted odds ratio = 1.04 (0.80-1.36); pneumonia: adjusted odds ratio = 1.21 (0.87-1.68); postoperative change in mental status: adjusted odds ratio = 1.08 (0.95-1.22). CONCLUSIONS: The authors were unable to demonstrate that regional anesthesia was associated with better outcome than was general anesthesia in this large observational study of elderly patients with hip fracture. These results suggest that the type of anesthesia used should depend on factors other than any associated risks of mortality or morbidity.

Complications of diabetes in the hospitalized population in Victoria, 1993-95.

A retrospective analysis of computerized data from the Victorian Inpatient Minimum Database (VIMD) was undertaken in order to describe the prevalence of diabetes and its associated complications in the hospitalized population over a 2-year period. While diabetes was rarely recorded as a principal cause of hospitalization (less than 0.5% of admissions), this condition was present in 4% (95,091) of the hospitalized population with a slight male excess. Cardiovascular disease was present in 60% of these diabetes-related admissions and was the principal diagnosis in a quarter of all cases. The prevalence of hypertension was 28%. Cardiovascular disease (CVD) was the principal diagnosis in 40% of in-hospital deaths, and in women, the risk of CVD death was 22% greater than it was for men. Diabetes-related complications were noted in 22%; 3.3% recorded renal disease, 2.7% peripheral vascular disease, and ophthalmic and neurological complications were recorded in 2.1% and 1.4%, respectively. Of all lower limb amputations carried out in Victoria over the period, 40% (1281) were in people with diabetes. Eye surgery was carried out on (6.8%) 6463 diabetes-related separations. There are recognized limitations of using routinely collected computerized data. Nevertheless, data relating to number of amputations and eye surgery in those with diabetes can be used as indicators of the success of diabetes care and national strategies for prevention.

How you look determines what you find: severity of illness and variation in blood transfusion for hip fracture.

PURPOSE: Utilization report cards are commonly used to assess hospitals. However, in practice, they rarely account for differences in patient populations among hospitals. Our study questions were: (1) How does transfusion utilization for hip fracture patients vary among hospitals? (2) What patient characteristics are associated with transfusion and how do those characteristics vary among hospitals? (3) Is the apparent pattern of variation of utilization among hospitals altered by controlling for these patient characteristics? SUBJECTS AND METHODS: We included consecutive hip fracture patients aged 60 years or older who underwent surgical repair between 1982 and 1993 in 19 hospitals from four states, excluding those who refused blood transfusion, had multiple trauma, metastatic cancer, multiple myeloma, an above the knee amputation, or were paraplegic or quadriplegic. The outcome of interest was postoperative blood transfusion. "Trigger hemoglobin" was the lowest hemoglobin recorded before transfusion or recorded at any time during the week before or after surgery for patients who were not transfused. RESULTS: There was considerable variation in transfusion among hospitals postoperatively (range 31.2% to 54.0%, P = 0.001). Trigger hemoglobin also varied considerably among hospitals. In unadjusted analyses, four of nine teaching and two of nine nonteaching hospitals had postoperative transfusion rates significantly higher than the reference (teaching) hospital, while one nonteaching hospital had a lower rate. In an analysis controlling for trigger hemoglobin and multiple clinical variables, one of nine teaching and four of nine nonteaching hospitals had rates higher than the reference hospital, while four teaching hospitals and one nonteaching hospital had lower rates. CONCLUSIONS: The apparent pattern of variation of transfusion among hospitals varies according to how one adjusts for relevant patient characteristics. Utilization report cards that fail to adjust for these characteristics may be misleading.

Perioperative blood transfusion and postoperative mortality.

CONTEXT: The risks of blood transfusion have been studied extensively but the benefits and the hemoglobin concentration at which patients should receive a transfusion have not. OBJECTIVE: To determine the effect of perioperative transfusion on 30- and 90-day postoperative mortality. DESIGN: Retrospective cohort study. SETTING: A total of 20 US hospitals between 1983 and 1993. PARTICIPANTS: A total of 8787 consecutive hip fracture patients, aged 60 years or older, who underwent surgical repair. MAIN OUTCOME MEASURES: Primary outcome was 30-day postoperative mortality; secondary outcome was 90-day postoperative mortality. The "trigger" hemoglobin level was defined as the lowest hemoglobin level prior to the first transfusion during the time period or, for patients in the nontranfused group, as the lowest hemoglobin level during the time period. RESULTS: Overall 30-day mortality was 4.6% (n=402; 95% confidence interval [CI], 4.1%-5.0%); overall 90-day mortality was 9.0% (n=788; 95% CI, 8.4%-9.6%). A total of 42% of patients (n=3699) received a postoperative transfusion. Among patients with trigger hemoglobin levels between 80 and 100 g/L (8.0 and 10.0 g/dL), 55.6% received a transfusion, while 90.5% of patients with hemoglobin levels less than 80 g/L (8.0 g/dL) received postoperative transfusions. Postoperative transfusion did not influence 30- or 90-day mortality after adjusting for trigger hemoglobin level, cardiovascular disease, and other risk factors for death: for 30-day mortality, the adjusted odds ratio (OR) was 0.96 (95% CI, 0.74-1.26); for 90-day mortality, the adjusted hazard ratio was 1.08 (95% CI, 0.90-1.29). Similarly, 30-day mortality after surgery did not differ between those who received a preoperative transfusion and those who did not (adjusted OR, 1.23; 95% CI, 0.81-1.89). CONCLUSIONS: Perioperative transfusion in patients with hemoglobin levels 80 g/L (8.0 g/dL) or higher did not appear to influence the risk of 30- or 90-day mortality in this elderly population. At hemoglobin concentrations of less than 80 g/L (8.0 g/dL), 90.5% of patients received a transfusion, precluding further analysis of the association of transfusion and mortality.

Evaluation of the safety and efficacy of ketorolac versus morphine by patient-controlled analgesia for postoperative pain.

STUDY OBJECTIVE: To compare ketorolac tromethamine with morphine for pain management after major abdominal surgery. DESIGN: Double-blind, randomized study. SETTING: Hospital recovery room and postoperative surgical unit. PATIENTS: One hundred ninety-one patients with at least moderate pain after major abdominal surgery. INTERVENTIONS: Patients received ketorolac by patient-controlled analgesia (PCA) bolus alone (Ket B), ketorolac by bolus plus infusion (Ket I), or morphine by PCA bolus (morphine), with injectable morphine available for supplementation. MEASUREMENTS AND MAIN RESULTS: Levels of sedation, pain intensity, pain relief, and adverse events were recorded at baseline, at 2, 4, and 6 hours, and at termination. Supplemental morphine was required by 71% of Ket B patients, 67% of Ket I patients, and 38% of morphine patients (p < or = 0.001 for Ket B vs morphine). Although patients receiving ketorolac required more supplemental morphine than the morphine group (6.0 mg Ket I, 6.2 mg Ket B, 4.0 mg morphine), there was a large morphine-sparing effect in both ketorolac groups (total morphine 6.0 mg Ket I, 6.2 mg Ket B, 33.3 mg morphine). Overall pain relief scores were similar for morphine and Ket I groups, and were lower for Ket B than for morphine (p = 0.002). There were no differences among groups in numbers of patients with adverse events. CONCLUSION: Ketorolac may be effective when administered by PCA device, and has a clear morphine-sparing effect.

Pharmacoeconomic analysis of sevoflurane versus isoflurane anesthesia in elective ambulatory surgery.

This study investigated the economic aspects of sevoflurane and isoflurane anesthesia in 47 healthy women undergoing elective ambulatory surgery, as part of a randomized, prospective clinical trial. Patient records were analyzed for anesthetic; duration of surgery, anesthesia, and recovery room stay; and associated charges. Sevoflurane is shorter acting than isoflurane, but it was not associated with a shorter duration of anesthesia or surgical unit stay, or earlier hospital discharge. Total charges associated with sevoflurane anesthesia were greater than those for isoflurane ($2641 and $2230, respectively) and primarily related to prolonged anesthesia and surgical unit stay. A minor decrease in recovery room charges ($15) associated with earlier discharge was observed with sevoflurane (p>0.05), but the agent was not associated with lower hospital charges. Larger trials and assessment of other patient populations may show sevoflurane to be more pharmacoeconomically advantageous than isoflurane.

The effect of intravenous ketorolac given intraoperatively versus postoperatively on outcome from gynecologic abdominal surgery.

STUDY OBJECTIVES: To examine the effect of timing of an intravenous (i.v.) dose (intraoperative vs. postoperative) of ketorolac tromethamine on pain scores and overall outcome after total abdominal hysterectomy (TAH) and myomectomy. DESIGN: Prospective, randomized, placebo-controlled study. PATIENTS: 248 ASA physical status I and II adult female patients scheduled for elective hysterectomy or myomectomy. INTERVENTIONS: General anesthesia was administered that consisted of thiopental sodium for induction, enflurane or isoflurane in nitrous oxide-oxygen for maintenance, and small doses of fentanyl and midazolam. Patients were randomized into three groups to receive toradol/placebo on a dosing schedule of dose 1 given one-half hour prior to expected end of surgery, dose 2 given on awakening in the postanesthesia care unit, and doses 3, 4, and 5 given at 6, 12, and 18 hours, respectively, after dose 2; Group 1 patients received placebo (saline) for dose 1, ketorolac 60 mg i.v. for dose 2, and ketorolac 30 mg i.v. for doses 3, 4, and 5. Group 2 patients received ketorolac 60 mg i.v. for dose 1, placebo for dose 2, and ketorolac 30 mg i.v. for doses 3, 4, and 5. Group 3 patients received placebo for all doses. All patients were given i.v. morphine PCA postoperatively, and morphine usages, visual analog pain intensity (VAS) scores, as well as adverse events and median times to recovery milestones were recorded. MEASUREMENTS AND MAIN RESULTS: VAS scores (mean) before dose 2 were significantly lower in Group 2 than Group 1, as were at-rest evaluations at 15 minutes and one hour. Group 2 patients also had decreased morphine requirements as compared to placebo. Both ketorolac groups (Groups 1 and 2) had significantly higher values for patient and observer overall ratings, case of nursing care, and tolerability as compared to placebo (Group 3). There were no significant differences among groups in adverse events or median times to recovery milestones. CONCLUSIONS: Although it is possible to demonstrate an improvement in early postoperative pain scores with intraoperative ketorolac and better overall ratings of ketorolac both intraoperatively and postoperatively as compared with placebo, the lack of clinically significant differences in analgesic efficacy in the two active study groups indicates the need for a careful consideration by the clinician of the risks versus benefits involved in the administration of antiplatelet medication in the perioperative period.

The use of a PID controller to model vecuronium pharmacokinetics and pharmacodynamics during liver transplantation. Proportional-integral-derivative.

A four-phase proportional-integral-derivative (PID) controller was evaluated under the extremely unstable conditions of liver transplantation. Vecuronium was delivered to achieve 80%-90% neuromuscular blockade as measured by electromyogram (EMG). The first two controller phases delivered boluses and a constant infusion calculated to rapidly achieve setpoint, followed by a proportional-derivative (PD) phase at 35% from setpoint, and PID within 10% of the setpoint. During liver transplantation, the sources of system instability included large blood losses, temperature changes, and loss of hepatic drug metabolism during removal and replacement. During prolonged surgery, and when blood losses were not severe, the EMG remained within 10% of setpoint. Controller performance was more variable during system instability. Plasma sampling and two-compartment modelling of the infusion and response with a weighting factor for blood loss allowed estimation of the sources and degree of instability for improved design of future controllers.

Drugs for amnesia in the ICU.

OBJECTIVE: This review focuses on how patients' recall of their stay in the ICU can be modified pharmacologically. DATA SOURCES: Computerized MEDLINE and PAPERCHASE searches of English- and foreign-language published research from 1966 to 1995, bibliographies, pharmaceutical and personal files, and conference abstract reports. STUDY SELECTION: All abstracts from uncontrolled and controlled clinical trials were reviewed. DATA EXTRACTION: Study design, population, results, and safety information were retained. Efficacy conclusions were drawn from controlled trials. DATA SYNTHESIS: Patients without cerebral injury may recall mental and physical discomfort during their stay in the ICU. All benzodiazepines produce amnestic effects, but the short duration of action, lack of long-acting metabolites, and potent amnestic effects make lorazepam and midazolam preferable in this setting. Infusions of propofol for conscious sedation produce concentrations below those required for consistent amnesia. Opioids generally do not produce amnesia; however, end-organ failure and use of high doses of opioids may increase plasma concentrations to levels that produce impairment of learning and various degrees of amnesia. High infusion rates of ketamine may be required for satisfactory amnesia and pain control (with coadministration of benzodiazepine). Barbiturates and haloperidol do not impair memory in patients who are not critically ill. Antihistamines and anticholinergics that do not penetrate the central nervous system do not produce amnesia. Flumazenil may induce recall. CONCLUSIONS: Patients may remember their stay in the ICU, depending on the type of injury and the drug therapy. Of the drugs presented, benzodiazepines most reliably provide anterograde amnesia, whereas ketamine and propofol exhibit dose-dependent effects on memory.

Reporting of adverse events in hospitals in Victoria, 1994-1995.

OBJECTIVE: To describe the nature and frequency of adverse events (AEs) reported in routine inpatient data collection. DESIGN: Retrospective analysis of data from the Victorian Inpatient Minimum Database. SETTING: All public (135) and private (112) acute-care hospitals in Victoria, 1994-1995. PARTICIPANTS: All patients with separations recording an E-code identified as an AE through the International classification of diseases, ninth revision (ICD-9), classification system. MAIN OUTCOME MEASURES: Australian national diagnosis-related groups (AN-DRGs) associated with AEs; prevalence of major organ system disease in each of the AE groups; AE rates by hospital type; and impact of AEs on discharge destination, or death. RESULTS: AEs were recorded in 5% of separations, with incidence increasing with patient age. Most (81%) were complications after surgery or other procedures (E878-E879); 19% were adverse drug effects (E930-E949) and 1.7% were misadventures (E870-E876). The most frequently reported complications were infections, haemorrhage and pneumonia. AN-DRGs--joint replacement of the lower limb, bowel excision and hysterectomy--contributed most to the volume of AEs, while the greatest risk was associated with ventricular shunt, major organ transplantation and surgery for complicated injuries. The in-hospital death rate in patients with AEs was 2.9% (95% confidence interval [95% CI], 2.7%-3.2%), compared with 1.3% (95% CI, 1.0-1.4) in those without an AE. Of patients with an AE, fewer were discharged directly home, and higher proportions were discharged to other acute-care facilities or nursing homes compared with those without an AE. CONCLUSION: Inpatient data collection can provide information about AE rates associated with individual procedures, and the nature of these AEs. It can be used by hospitals to direct and complement their own quality improvement activities. Its limitation is that it cannot identify the severity or long term outcome of AEs.

Pharmacokinetics and pharmacodynamics of sedatives and analgesics in the treatment of agitated critically ill patients.

The pharmacokinetics and pharmacodynamics of sedatives and analgesics are significantly altered in the critically ill. These changes may account for the large differences in drug dosage requirements compared with other patient populations. Drugs that in other settings may be considered short-acting often have significantly altered onset and duration of action in critically ill patients, necessitating a change in dosage. Of the benzodiazepines, lorazepam is the drug whose parameters are the least likely to be altered in critical illness. The presence of active metabolites with other benzodiazepines complicates their use during periods of prolonged use. Similarly, the presence of active metabolites of morphine and pethidine (meperidine) warrants caution in patients with renal insufficiency. The fewer cardiovascular effects seen with high-potency opioids, such as fentanyl and sufentanil, increase their usefulness in haemodynamically compromised patients. The pharmacodynamics of propofol are not significantly altered in the critically ill. Ketamine should be used with a benzodiazepine to prevent the emergence of psychomimetic reactions. Lower sedative doses of benzodiazepines and anaesthetics may not provide reliable amnesia. Barbiturates and propofol probably do not induce hyperalgesia and lack intrinsic analgesic activity. The antipsychotic agent haloperidol has a calming effect on patients and administration to the point of sedation is generally not necessary. Combinations of sedatives and analgesics are synergistic in producing sedation. The costs of sedation and analgesia are very variable and closely linked to the pharmacokinetics and pharmacodynamics of the drug. Monitoring of sedation and analgesia is difficult in uncooperative patients in the intensive care unit. In the future, specific monitoring tools may assist clinicians in the regulation of infusions of sedative and analgesic agents.

A double-blind, placebo-controlled evaluation of intranasal metoclopramide in the prevention of postoperative nausea and vomiting.

Nausea and vomiting are common complaints in the postoperative period and contribute to patient distress and delay of discharge for outpatient surgical procedures. Laparoscopic procedures are associated with a high incidence of postoperative nausea and vomiting (PONV) episodes. Parenteral use of metoclopramide prevents and treats PONV. The intranasal route provides rapid and complete absorption of metoclopramide without many of the adverse effects observed with parenteral administration of the drug. We performed a prospective, double-blinded, randomized, placebo-controlled study to evaluate the safety and efficacy of metoclopramide 20 mg administered intranasally for emetic prophylaxis in laparoscopic surgery patients. The results from 109 patients enrolled in the study showed that this intranasal dose of metoclopramide may be ineffective in preventing the occurrence of PONV. The poor performance of the intranasal metoclopramide formulation in this study cannot be attributed to patient-specific and perioperative factors. It may be due to an inadequate dose or slow absorption of the drug. The small sample size, however, may also have been a factor.

The effects of sevoflurane and isoflurane on recovery from outpatient surgery.

This randomized, open-label study compared the investigational inhalational anesthetic sevoflurane with isoflurane in 47 healthy women undergoing elective ambulatory surgery. The women were randomized to receive either sevoflurane or isoflurane in 60% nitrous oxide-oxygen. Induction with thiopental 3-6 mg/kg was followed by vecuronium 0.1 mg/kg and fentanyl 0-200 micrograms. Duration of anesthesia, time to emergence, orientation, length of stay in the surgical unit, and hospital discharge were recorded. The emergence, length of stay, and discharge times after discontinuation of sevoflurane were 9.7 +/- 0.7, 120.6 +/- 8.0, and 244 +/- 15 minutes, respectively, and for isoflurane were 11.9 +/- 1.4, 106.8 +/- 7.1, and 282 +/- 24 minutes, respectively (NS). The isoflurane group had a higher frequency of postoperative cough. At the end of surgery, the sevoflurane group received a deeper level of anesthesia (minimum alveolar concentration 1.5 vs 1.3), however, these patients were oriented earlier (13.6 +/- 1.1 min vs 17.0 +/- 1.5 min isoflurane; p = 0.02) after discontinuation of anesthesia, although this difference is of little clinical significance.

Comparison of intranasal midazolam and sufentanil premedication in pediatric outpatients.

BACKGROUND: Intranasally administered midazolam was compared with sufentanil as a premedicant for 60 patients, aged 1/2 to 6 years, undergoing outpatient surgery of 2 hours or less. METHODS: Thirty minutes before anesthetic induction (halothane in 50% nitrous oxide/oxygen), patients were randomly assigned to receive either intranasal midazolam (0.2 mg/kg) or sufentanil (2 microg/kg). A "blinded" observer evaluated preoperative emotional state, response to premedication, induction, and emergence from anesthesia and side effects. RESULTS: Children who had not previously cried were more likely to cry when midazolam was administered compared with sufentanil (71% versus 20%, p = 0.0031). Of 31 midazolam patients, 20 experienced nasal irritation. Approximately 15 to 20 minutes after drug administration, most patients in both groups could be comfortably separated from their parents. The sufentanil group appeared to be more sedated and more cooperative during induction of anesthesia. Vital signs and oxygen saturation did not change significantly with either medication before or after surgery, although two sufentanil patients had a moderate reduction in ventilatory compliance after anesthetic induction. Sufentanil was associated with more nausea and vomiting than midazolam (34% versus 6%, p < 0.02). CONCLUSION: Both intranasal midazolam and sufentanil provide rapid, safe, and effective sedation in small children before anesthesia for ambulatory surgery. Sufentanil provided somewhat better conditions for induction and emergence. Midazolam causes more nasal irritation during instillation, and sufentanil causes more postoperative nausea and vomiting. Both drugs enabled patients to be separated from their parents with a minimum of distress. Patients in the midazolam group were discharged approximately 40 minutes earlier (p <0.005).

Cost analysis of propofol versus thiopental induction anesthesia in outpatient laparoscopic gynecologic surgery.

This study investigated the cost of propofol versus thiopental anesthesia in 243 patients who underwent outpatient laparoscopic gynecologic surgery. Patients records were analyzed for medication use, duration of surgery, anesthesia, recovery room stay, and associated costs. Despite the higher drug cost for propofol, the total mean cost was $273.00 less per patient for patients receiving propofol induction anesthesia. Extension of these data translates into cost savings of approximately $7900.00 if propofol had been used for all patients. Although the duration of surgery for the propofol group was shorter by nearly 12 minutes, the anesthesia duration and recovery room stay were both longer for the thiopental group, reflecting the longer duration of action of thiopental. Although the realized cost savings of drugs, surgery, anesthesia, and recovery time when propofol versus thiopental is used for outpatient laparoscopic gynecologic surgery are relatively small on an individual patient basis, cost savings may become more significant if larger patient populations are studied.

Retrospective analysis of postoperative nausea and vomiting to determine antiemetic activity of droperidol added to propofol: a possible drug interaction.

Propofol decreases the frequency of postoperative nausea and vomiting. We investigated whether its antiemetic activity could be improved further by coadministration of droperidol. We retrospectively reviewed the records of 266 women who underwent laparoscopic operations with nitrous oxide anesthesia and thiopental or propofol induction. The records were screened for frequency and time of occurrence of nausea and vomiting, concurrent drug use, duration of surgery, and times of recovery room admission and discharge. The combination of droperidol and thiopental decreased the frequency of nausea and vomiting over droperidol plus propofol, propofol alone, and thiopental alone. The addition of droperidol to propofol anesthesia doubled the frequency of multiple nausea and vomiting episodes, suggesting a possible interaction between the drugs. We cannot recommend that droperidol be added to propofol anesthesia for prophylaxis of postoperative nausea and vomiting.

Effects of pentobarbital and isoflurane on regional cerebral oxygen extraction and consumption with middle cerebral artery occlusion in rats.

BACKGROUND: When compared with barbiturates, isoflurane may lack protective effects during focal cerebral ischemia. The reason for this difference is not clear. In this study, regional cerebral blood flow (rCBF), arterial and venous O2 saturation, and O2 extraction were compared in the ischemic cortex and in the nonischemic brain regions of rats anesthetized with isoflurane or pentobarbital using a microspectrophotometric technique that directly measures the O2 saturation of blood in the small arteries and veins. METHODS: Twenty-eight rats were anesthetized with 1.4% isoflurane or 50 mg/kg pentobarbital. One hour after a middle cerebral artery (MCA) occlusion, rCBF was measured in the ischemic cortex and in the nonischemic brain regions using 14C-iodoantipyrine in one-half of each group of animals. Regional arterial and venous O2 saturation were determined using microspectrophotometry in the other one-half of each group. RESULTS: The rCBF of the ischemic cortex (IC) and the non-ischemic contralateral cortex (CC) of the isoflurane group were significantly higher than those of the pentobarbital group. The venous O2 saturation was significantly less, and the O2 extraction was significantly higher, in the IC than in the nonischemic regions in both groups of animals (pentobarbital group, IC 10.5 +/- 1.1 ml O2.100 ml blood-1, CC 6.3 +/- 0.7; isoflurane group, IC 10.8 +/- 0.6, CC 5.9 +/- 0.2). There was no significant difference between the two groups. CONCLUSIONS: Because the rCBF was less and the O2 extraction was similar, O2 consumption in the focal ischemic area of the brain during pentobarbital anesthesia must have been less than that during isoflurane anesthesia.