Jan Van Hemelrijck

Use of desflurane for outpatient anesthesia. A comparison with propofol and nitrous oxide.

Desfluranes induction and recovery characteristics were compared to those of propofol-nitrous oxide in outpatients undergoing laparoscopic procedures. Ninety-two healthy patients were randomized to receive either: 1) propofol induction and propofol-nitrous oxide maintenance (control), 2) propofol induction and desflurane-nitrous oxide maintenance, 3) desflurane-nitrous oxide, or 4) desflurane alone for induction and maintenance of anesthesia. Inhalation induction with desflurane-nitrous oxide was faster than with desflurane alone (100 +/- 35 vs. 124 +/- 43 s). Inhalation inductions were associated with a high incidence of apnea (17 and 26%), breath-holding (26 and 39%), and coughing (30 and 22%) in groups 3 and 4, respectively. The emergence time after discontinuation of desflurane in oxygen (4.5 +/- 2.1 min.) was significantly less than that after propofol-nitrous oxide (7.3 +/- 3.9 min.). However, times from arrival in the recovery room until the patients were judged fit for discharge were similar for all four treatment groups. Digit-symbol substitution test results and sedation visual analogue scores also were similar during the first 2 h in the recovery room. A lower incidence of moderate-to-severe nausea was reported in group 1 (15% vs. 52, 52, and 59% in groups 2, 3, and 4, respectively). In conclusion, induction of anesthesia with desflurane was rapid but is associated with a high incidence of airway irritation. Emergence and recovery profiles after maintenance of anesthesia with desflurane compared favorably to a propofol-nitrous oxide combination. However, propofol was associated with a lower incidence of nausea than was desflurane after outpatient anesthesia for laparoscopic surgery.

Effect of Propofol on Cerebral Circulation and Autoregulation in the Baboon

The purpose of this study was to investigate the effect of propofol on cerebral blood flow, cerebral metabolism, and cerebrovascular autoregulatory capability. Seven anesthetized baboons were given propofol at three different infusion rates. An infusion of 3 mg·kg−1·h−1 caused minimal changes, but infusion rates of 6 and 12 mg·kg−1·h−1 decreased cerebral blood flow by 28% and 39%, respectively. The changes in cerebral metabolic rate of oxygen were not statistically significant. However, with the two higher infusion rates, there was a trend toward decrease, by 5% and 22%, respectively, for the cerebral metabolic rate of oxygen, and by 18% and 36% for the cerebral metabolic rate of glucose. A 25–30 mm Hg increase in arterial blood pressure had no influence on cerebral blood flow. Replacement of nitrous oxide by nitrogen had no significant influence on cerebral blood flow or metabolism.It is concluded that propofol causes a dose-dependent decrease in cerebral blood flow. However, the study does not prove that this decrease in cerebral blood flow is accompanied by the same degree of decrease in cerebral metabolism. Further studies are clearly needed to clarify propofols influence on the coupling between cerebral metabolism and blood flow. The physiologic responsiveness of the cerebral circulation to alterations in arterial pressure is well preserved. Propofol appears to prevent the metabolic stimulation and increased cerebral blood flow that has been associated with the administration of nitrous oxide.

Influence of hydroxyethyl starch on coagulation in patients during the perioperative period

The perioperative use of hydroxyethyl starch (HES) has been implicated as a possible cause of intracranial bleeding. The purpose of this study was to compare the influence on blood coagulation of the isovolemic replacement of 1-L blood loss with either 6% HES (molecular weight [MW] average: 450,000) or 5% human albumin during neurosurgery or lower abdominal surgery. Twenty patients scheduled for brain tumor surgery and 20 patients undergoing transabdominal hysterectomy were studied. The activated partial thromboplastin time, prothrombin time, fibrinogen concentration, factor VIII coagulant, von Willebrand factor antigen, platelet count, and the activated clotting time were compared after induction of anesthesia, after administration of 500 and 1000 mL of colloid solution, and 24 and 48 h postoperatively. All measured coagulation variables remained within physiologic range. Changes in coagulation indices were identical in neurosurgical and hysterectomy patients, except for a larger increase in fibrinogen concentration 24 and 48 h after hysterectomy. The acute phase reaction of factor VIII coagulant and von Willebrand factor, which plays a role in postoperative hypercoagulability, was attenuated by the use of HES. We conclude that isovolemic replacement of 1-L blood loss with either 6% HES (MW average: 450,000) or 5% human albumin does not interfere with normal hemostasis during and after neurosurgery or lower abdominal surgery.

Light anaesthesia with propofol for paediatric MRI

Anaesthetic techniques and monitoring equipment may interfere with the technical demands of magnetic resonance imaging. The purpose of this study was to evaluate the safety and efficacy of a light anaesthetic technique with intravenous propofol in nonintubated children. In 20 neuropaediatric patients sedation was induced with propofol 1 mg.kg−1, followed by a continuous infusion titrated to produce adequate immobilisation. Oxygen, 4 l.min−1, was administrated by paediatric face mask. Respiratory rate, end‐tidal carbon dioxide tension and oxygen saturation were continuously monitored. In 10 patients capillary blood gas tensions were determined 3 and 20 min after the procedure. Data are reported as mean (SD) and the mean (SD) total propofol dose was 5 (2) mg.kg−1.h−1. Oxygen saturation remained constantly higher than 96% in all patients. End‐tidal carbon dioxide tension varied between 35 (7) mmHg 3 min after induction, and 41 (6) mmHg 30 min after the start of the procedure. End‐tidal to capillary PCO2 difference was 4 (3) mmHg. Within 20 min after the end of the procedure all patients were fit for dismissal to the ward. One imaging sequence out of 49 was repeated because of movement artefacts. In conclusion, intravenous propofol sedation appears to be a safe and reliable technique for paediatric sedation during magnetic resonance imaging.

Efficacy of esmolol versus alfentanil as a supplement to propofol-nitrous oxide anesthesia.

In 97 outpatients undergoing ambulatory arthroscopic procedures, we compared esmolol with alfentanil when used to supplement propofol-N2O-atracurium anesthesia according to a randomized, double-blind protocol. After an initial intravenous dose of 16 micrograms/kg alfentanil, or 2 mg/kg of esmolol, a variable-rate infusion of alfentanil or esmolol was administered to maintain a stable heart rate. After induction of anesthesia with 2.5 mg/kg of propofol, mean arterial pressure decreased to a larger extent in the alfentanil-treated patients. Although heart rate and mean arterial pressure increased in both groups after tracheal intubation, alfentanil more effectively blunted the hemodynamic response to this stimulus. Maintenance of anesthesia was adequate in both treatment groups. After discontinuation of anesthesia, patients in the esmolol group opened their eyes earlier (7.2 +/- 2.4 min vs 9.8 +/- 4.6 min) than those in the alfentanil group. Esmolol-treated patients also reported less sedation in the first 15 min of recovery than those receiving alfentanil. However, there were no differences in times to ambulation and discharge between the groups. Esmolol-treated patients reported more postoperative pain for the first 15 min of recovery and more esmolol-treated patients required postoperative opioid analgesia than those treated with alfentanil. There were no significant differences in the incidences of nausea and vomiting between the two groups. The authors conclude that esmolol may be used in place of alfentanil to supplement propofol-N2O-atracurium anesthesia in outpatients undergoing arthroscopic procedures. However, hemodynamic responses to tracheal intubation were larger with esmolol, and avoidance of alfentanil did not decrease the incidence of postoperative nausea and vomiting in this outpatient population.

Relative Potency of Eltanolone, Propofol, and Thiopental for Induction of Anesthesia

BackgroundThe primary purpose of this investigation was to determine the relative potency of eltanolone, a new steroid hypnotic, and propofol and thiopental when used for induction of general anesthesia. In addition, the induction characteristics of propofol and eltanolone were compared. MethodsOne hundred seventy-five patients, premedicated with lorazepam 1 mg orally, randomly received one of six different doses of either eltanolone or propofol. The probability of successful induction (deined as not responsive to verbal commands within 2 min) was related to the logarithm of the dose for each drug by means of logistic regression analysis. Estimates of ED50 and ED95 for each drug were obtained. The incidence of side effects was compared for eltanolone and propofol. The potency of thiopental was determined in a parallel study, using an identical methodology in 105 patients receiving one of seven different doses of the barbiturate. ResultsThe relative potency of eltanolone was 3.2 times (95% confidence interval 2.7–3.8) greater than propofol and 6.0 times (5.3–6.9) greater than thiopental. ED50 and ED95 values for eltanolone were 0.46 (0.40–0.52) and 0.82 (0.68–1.28) mg.kg–1, respectively. Compared to propofol, induction of anesthesia with eltanolone is characterized by a lower incidence of injection pain (3.5% vs. 58%) and apnea (1.2% vs. 11.2%). ConclusionsEltanolone appeared to be an effective induction agent that is 3.2 times more potent than propofol and 6 times more potent than thiopental. Its use was associated with less pain on injection than was propofol.

Propofol anesthesia does not inhibit stimulation of cortisol synthesis

Recent data suggest a negative effect of propofol anesthesia on cortisol secretion.The present study was designed to evaluate the effect of propofol anesthesia on the steroidogenic potential of the adrenal glands. The response of cortisol secretion to stimulation with an adrenocorticotropic hormone (ACTH) analog during intravenous anesthesia with propofol has not been reported before. The response of the secretion of cortisol, 11-deoxycortisol, and 17 alpha-hydroxyprogesterone to tetracosactide stimulation was compared in patients anesthetized with propofol-nitrous oxide (n = 10) or thiopental-isoflurane-nitrous oxide (n = 10) and in normal volunteers (n = 10). The response to tetracosactide was similar in all three groups. An adequate increase in cortisol plasma concentration (more than 7.25 micro gram/dL) was obtained in all subjects except one volunteer. The increase in the plasma concentration of the cortisol precursors was also similar. We were unable to detect any influence of propofol anesthesia on the synthesis of cortisol in response to tetracosactide stimulation. (Anesth Analg 1995;80:573-6)

Anesthesia for craniotomy: Total intravenous anesthesia with propofol and alfentanil compared to anesthesia with thiopental sodium, isoflurane, fentanyl, and nitrous oxide

STUDY OBJECTIVE To compare a total intravenous (IV) anesthetic technique based on propofol and alfentanil with a commonly used anesthetic technique for craniotomy. DESIGN Open-label, randomized, clinical study. SETTING Neurosurgical clinic at a university hospital. PATIENTS Forty patients, aged 18 to 55 years, scheduled for brain tumor surgery. INTERVENTIONS In 20 patients, anesthesia was induced with fentanyl and thiopental sodium and maintained with fentanyl, dehydrobenzperidol, isoflurane, nitrous oxide (N2O), and a thiopental sodium infusion. Twenty patients were anesthetized with a propofol loading infusion followed by a maintenance infusion at a fixed rate. In addition, alfentanil was administered as a loading bolus, followed by a variable-rate infusion, with additional doses as necessary to maintain hemodynamic stability. MEASUREMENTS AND MAIN RESULTS A decrease in blood pressure (BP) after induction with thiopental sodium was followed by a significant increase in BP and heart rate (HR) during intubation. BP and HR did not change during the propofol loading infusion. However, the administration of alfentanil was followed by a similar decrease in BP with a return to baseline values during the intubation period. Return of normal orientation (7 +/- 5 minutes vs 27 +/- 23 minutes) and concentration (12 +/- 12 minutes vs 35 +/- 37 minutes) was shorter and more predictable for the propofol-alfentanil-treated patients than for the thiopental sodium patients. Maintenance propofol concentration (nine patients) was between 3 +/- 0.69 micrograms/ml and 3.36 +/- 1.17 micrograms/ml, while the concentration at awakening was 1.09 microgram/ml. Alfentanil concentration at extubation (nine patients) was 79 +/- 34 ng/ml. CONCLUSION A total IV anesthetic technique with propofol and alfentanil is a valuable alternative to a more commonly used technique based on thiopental sodium, N2O, fentanyl, and isoflurane.

Partial left ventricular support implanted through minimal access surgery as a bridge to cardiac transplant

the bilateral axillary arteries had been routinely prepared for selective cerebral perfusion at the Hiroshima University Hospital. The addition of FA-P might be another strategy in other institutions. Because there are unpredictable factors in acute aortic dissection, decisions need to be made stepwise and be based on real-time information at each step. Although our initial assessment was incorrect, TEE and orbital Doppler findings steered the subsequent management toward a good outcome. Compression of IA can be a mechanism of malperfusion after right AX-P. In acute aortic dissection with many unpredictable factors, real-time, on-site information is essential for intraoperative navigation.

Training needs and qualifications of anaesthesiologists not exposed to ALS

OBJECTIVES To establish which needs exist for specific training in Advanced Cardiac Life Support (ALS) in anaesthesiology residents and interns not exposed to structured ALS courses. METHODS 48 residents, and seven interns accepted for training in anaesthesiology, were tested in a spontaneous, blind, cross-sectional, prospective assessment using a recording manikin with validated scoring system, a questionnaire, and 35 multiple-choice questions. RESULTS 65% admitted not having had any CPR training within the last 2 years. The answers were correct in 55 +/- 14% of the cases, increasing significantly with the length of training (P = 0.001). One-rescuer CPR skills were inadequate: only 13% (n = 7) of participants scored within acceptable limits when using the Berden Scoring system (Berden et al., Resuscitation 1992;13:31-41), which assigned weighted error points to BLS skills. No correlation with skill was noted with increased length of residency, confidence, ER or ICU experience, or participation in CPR-incidents. CONCLUSIONS Anaesthesiology residents and interns were not able to demonstrate BLS skills properly even while in training and did not recognize this themselves. CPR-related knowledge is poor and increases only incidentally over the years of residency even though participants were frequently confronted with seminars and resuscitation situations, and see protocols daily. The use of multiple-choice questions and the Berden scoring system avoids difficulties in evaluating case-scenario type of tests. We suggest that trainees are motivated to take part in standardized, intensive, recognised ALS courses which emphasize BLS skills and require (re)certification.