Peter S. A. Glass

bispectral Analysis Measures Sedation and Memory Effects of Propofol, Midazolam, Isoflurane, and Alfentanil in Healthy Volunteers

Background:The bispectral index (BIS), a value derived from the electroencephalograph (EEG), has been proposed as a measure of anesthetic effect. To establish its utility for this purpose, it is important to determine the relation among BIS, measured drug concentration, and increasing levels of seda

Goal-directed intraoperative fluid administration reduces length of hospital stay after major surgery.

Background Intraoperative hypovolemia is common and is a potential cause of organ dysfunction, increased postoperative morbidity, length of hospital stay, and death. The objective of this prospective, randomized study was to assess the effect of goal-directed intraoperative fluid administration on length of postoperative hospital stay. Methods One hundred patients who were to undergo major elective surgery with an anticipated blood loss greater than 500 ml were randomly assigned to a control group (n = 50) that received standard intraoperative care or to a protocol group (n = 50) that, in addition, received intraoperative plasma volume expansion guided by the esophageal Doppler monitor to maintain maximal stroke volume. Length of postoperative hospital stay and postoperative surgical morbidity were assessed. Results Groups were similar with respect to demographics, surgical procedures, and baseline hemodynamic variables. The protocol group had a significantly higher stroke volume and cardiac output at the end of surgery compared with the control group. Patients in the protocol group had a shorter duration of hospital stay compared with the control group: 5 ± 3 versus 7 ± 3 days (mean ± SD), with a median of 6 versus 7 days, respectively (P = 0.03). These patients also tolerated oral intake of solid food earlier than the control group: 3 ± 0.5 versus 4.7 ± 0.5 days (mean ± SD), with a median of 3 versus 5 days, respectively (P = 0.01). Conclusions Goal-directed intraoperative fluid administration results in earlier return to bowel function, lower incidence of postoperative nausea and vomiting, and decrease in length of postoperative hospital stay.

Bispectral index monitoring allows faster emergence and improved recovery from propofol, alfentanil and nitrous oxide anesthesia

Background: The bispectral index (BIS), a parameter derived from the electroencephalograph (EEG), has been shown to correlate with increasing sedation and loss of consciousness. This study determined whether addition of BIS monitoring to standard anesthetic practice results in improvements in the conduct of anesthesia or in patient outcomes. Methods: Three hundred two patients receiving a propofol‐alfentanil‐nitrous oxide anesthetic were studied at four institutions. Thirty‐four patients were initially enrolled to determine preexisting anesthetic practice and patient outcomes at each institution. Subsequent patients were randomized to either standard clinical practice (SP group), or standard practice plus BIS monitoring (BIS group). In all patients, the anesthesiologist attempted to provide a stable anesthetic with the fastest possible recovery. BIS was recorded for all patients, but viewed only in the BIS group. In the BIS group, propofol infusions were adjusted to achieve a target BIS between 45–60, increasing to 60–75 during the final 15 min of the case. In the SP group, propofol dose adjustments were made based only on standard clinical signs. Drug use, intraoperative responses, and patient recovery parameters were recorded. Results: Demographics were similar between groups. Compared with the SP group, patients in the BIS group required lower normalized propofol infusion rates (134 vs. 116 micro gram [center dot] kg sup ‐1 [center dot] min sup ‐1; P < 0.001), were extubated sooner (11.22 vs. 7.25 min; P < 0.003), had a higher percentage of patients oriented on arrival to PACU (43% vs. 23%; P < 0.02), had better postanesthesia care unit (PACU) nursing assessments (P < 0.001), and became eligible for discharge sooner (37.77 vs. 31.70 min; P < 0.04). There was no significant difference in the incidence of intraoperative responses between the groups. Conclusions: Titrating propofol with BIS monitoring during balanced anesthesia decreased propofol use and significantly improved recovery. Intraoperative course was not changed. These findings indicate that the use of BIS may be valuable in guiding the administration of propofol intraoperatively.

Preliminary Pharmacokinetics and Pharmacodynamics of an Ultra-short-acting Opioid: Remifentanil (gi87084b)

Remifentanil is a newly synthesized 4-anilidopiperidine with an ester side chain susceptible to esterase metabolism. We evaluated the safety, analgesic efficacy, and pharmacokinetics of remifentanil in 48 male volunteers. Volunteers were randomized to receive increasing doses of remifentanil, alfentanil, or placebo. Analgesic efficacy was evaluated by increasing tolerance to a spring-loaded rod measured at the tibia and sternum at multiple time points. Respiratory depression was measured by changes in arterial blood gas tensions and peripheral hemoglobin oxygen saturation. Hemodynamics were continuously monitored by means of an intra-arterial catheter. Both remifentanil and alfentanil produced a dose-dependent increase in analgesia and respiratory depression. Remifentanil was 20 to 30 times more potent (milligram to milligram) than alfentanil when assessed by either analgesic efficacy or respiratory measures. The pharmacokinetics of remifentanil were best described by a biexponential decay curve. Remifentanil had a small volume of distribution of 0.39 (SD, ±0.25) L/kg (alfentanil, 0.52 ± 2 L/kg), with a rapid distribution phase of 0.94 (SD, ±0. 57) min and an extremely short elimination half-life of 9.5 (SD, ±4) min compared with an elimination half-life of alfentanil of 58 (SD, ±7.6) min. The t1/2 ke0 (half-time for equilibration between plasma and the effect compartment) of remifentanil for analgesia was calculated as 1.3 min. Thus, remifentanil appears to have a pharmacologic profile similar to other potent μ agonists, but with exceptionally short-lasting pharmacokinetics, which is likely to make it a very useful opioid for clinical practice.

Measured Context-sensitive Half-times of Remifentanil and Alfentanil

BackgroundThe context-sensitive half-time, rather than the terminal elimination half-life, has been proposed as a more clinically relevant measure of decreasing drug concentration after a constant infusion of a given duration. The context-sensitive half-time is derived from computer modelling using

The effect of the interaction of propofol and alfentanil on recall, loss of consciousness, and the bispectral index

The Bispectral Index (BIS) correlates well with the level of consciousness with single anesthetic drugs.We studied the effect of the interaction of propofol with alfentanil on propofol concentration and BIS associated with 50% probability of loss of consciousness and lack of recall (Cp50 and BIS50,

Cost-effectiveness of Prophylactic Antiemetic Therapy with Ondansetron, Droperidol, or Placebo

Background: In an era of growing economic constraints on healthcare delivery, anesthesiologists are increasingly expected to understand cost analysis and evaluate clinical practices. Postoperative nausea and vomiting (PONV) are distressing for patients and may increase costs in an ambulatory surgical unit. The authors compared the cost-effectiveness of four prophylactic intravenous regimens for PONV:—4 mg ondansetron, 0.625 mg droperidol, 1.25 mg droperidol, and placebo. Methods: Adult surgical outpatients at high risk for PONV were studied. Study drugs were administered intravenously within 20 min of induction of nitrous oxide–isoflurane or enflurane anesthesia. A decision-tree analysis was used to group patients into 12 mutually exclusive subgroups based on treatment and outcome. Costs were calculated for the prevention and treatment of PONV. Cost-effectiveness analysis was performed for each group. Results: Two thousand sixty-one patients were enrolled. Efficacy data for study drugs have been previously reported, and the database from that study was used for pharmacoeconomic analysis. The mean–median total cost per patient who received prophylactic treatment with 4 mg ondansetron, 0.625 mg droperidol, 1.25 mg droperidol, and placebo were

Opioid-sparing Effects of a Low-dose Infusion of Naloxone in Patient-administered Morphine Sulfate

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A comparison of the efficacy, safety, and patient satisfaction of ondansetron versus droperidol as antiemetics for elective outpatient surgical procedures

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Use of patient-controlled analgesia to compare the efficacy of epidural to intravenous fentanyl administration.

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