Betamethasone does not prevent nausea and vomiting induced by ipecacuanha

BACKGROUND: Corticosteroids reduce the incidence of PONV but the mode of action is not known. The purpose of this study was to evaluate if betamethasone has serotonin (5-HT) antagonistic effects. Ipecacuanha is known to release serotonin and therefore it was used to induce nausea and vomiting. The 5-HT3 antagonist ondansetron was used as a control substance. METHODS: In a randomized, double-blind, cross-over, placebo-controlled study 10 healthy male and female volunteers (6 M/4F), mean age 19.5 (18-23) years, mean weight 69.7 (53-84) kg, were studied on three occasions separated by at least 1 week. They were randomly allocated to receive pretreatment with betamethasone 8 mg, ondansetron 8 mg, or normal saline 2 ml as placebo on each occasion, 15 min before oral ingestion of 30 ml of Ipecacuanha syrup. After ingestion of ipecacuanha, vomitings were recorded and the intensity of nausea was estimated with a visual analog scale during 2 h. RESULTS: During the first 2 h after ingestion of ipecacuanha nine of the 10 volunteers vomited both after betamethasone and placebo. No volunteer vomited after ondansetron (P < 0.01 vs. betamethasone and placebo). The max VAS for nausea was significantly higher after betamethasone and placebo compared to ondansetron (P < 0.01). There were no statistically significant differences of the max VAS for nausea between betamethasone and placebo. CONCLUSION: This study in volunteers has shown that betamethasone does not prevent nausea and vomiting induced by oral intake of ipecacuanha syrup. As ipecacuanha releases 5-hydroxytryptamin, it can be concluded that betamethasone does not have 5-HT3 antagonistic effects.     

Desflurane versus propofol maintenance for outpatient laparoscopic cholecystectomy

Background : The aims of the study were to evaluate costs and clinical characteristics of desflurane-based anaesthetic maintenance versus propofol for outpatient cholecystectomy.
Methods : All 60 patients received ketamine 0.2 mg kg^-1, fentanyl 2 μg kg^-1 and propofol 2 mg kg^-1 for induction. Ketorolac 0.4 mg kg^-1 and ondansetron 0.05 mg kg^-1 +droperidol 20 μg Kg^-1 was given as prophylaxis for postoperative pain and emesis, respectively. The patients were randomly assigned into Group P with propofol maintenance and opioid supplements, or Group D with desflurane in a low-flow circuit system.
Results : All the patients were successfully discharged within 8 h without any serious complications. Emergence from anaesthesia was more rapid after desflurane; they opened their eyes and stated date of birth at mean 6.4 and 8.4 min respectively, compared with 9.6 and 12 min in the propofol group (P<0.05). Nausea and pain were more frequent in Group D, 40% and 80% respectively; versus 17% and 50% in Group P (P<0.05). By telephone interview at 24 h and 7 d after the procedure, there was no major difference between the groups. With desflurane, drug costs per case were 10 $ lower than with propofol.
Conclusion : We conclude that desflurane is cheaper and has a more rapid emergence than propofol for outpatient cholecystectomy. However, propofol results in less pain and nausea in the recovery unit. Despite ondansetron and droperidol prophylaxis, there was still a substantial amount of nausea and vomiting after desflurane.     

Propofol sedation and gastric emptying in volunteers

Background : The purpose of this study was to evaluate the effects of light propofol sedation on gastric emptying and orocecal transit time (OCT).
Methods : Ten healthy male volunteers were studied on 2 occasions separated by at least 1 week and were randomly allocated to receive either propofol sedation or i.v. saline as a control. During propofol sedation the volunteers were sedated to grade 2–3 on a 5-grade scale. This was achieved by a propofol infusion of 5 mg kg^-1 h^-1 initially, which was then titrated down to a dose of 2.4±0.7 mg kg^-1 h^-1 Paracetamol absorption was used as an indirect measure of the rate of gastric emptying and OCT was determined by use of the hydrogen breath test after ingestion of raffinose. Student's t -test for paired samples was used and the results are presented as means± SD.
Results: During propofol sedation the maximum concentration of paracetamol (C_max) was 115±26.8μl/L, time to peak concentration (T_max) 50±38.8 min, and the area under the curve during the first 60 min (AUC₆₀4793±1538 μmolXmin/L, versus C_max 99±20.8, T_max 69±41.9 and AUC₆₀ 3897±1310 during saline infusion. These differences were not statistically significant. OCT was significantly shorter during the control study, 180±32.4 min, than during propofol sedation, 217±64.9 min (P<0.05).
Conclusion : This study in volunteers has shown that gastric emptying of liquids seems uninfluenced by light propofol sedation. OCT was slightly prolonged during light propofol sedation.     

A comparison of the effects of fentanyl and propofol on left ventricular contractility during myocardial stunning

Background : The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could protect the heart and improve recovery of ventricular contractile function in open-chested dogs.
Methods : Twenty adult beagles were acutely instrumented, under halothane anaesthesia, to measure ECG; aortic, left ventricular pressures; cardiac output; coronary flow; and segmental lengths in the regions perfused by the left anterior and left circumflex coronary arteries. After surgery and a stabilisation period halothane anaesthesia was terminated and fentanyl (100 μg. kg^-1 bolus followed by 2 μ.kg^-1·min^-1 infusion; n=10) or propofol (5 mg. kg^-1 bolus followed by 0.3 mg· kg^-1 min^-1 infusion; n=10) anaesthesia commenced. After a stabilisation period the LAD coronary artery was occluded for 10 min and then reperfused for 3 h. Measurements were taken throughout the protocol.
Results : We found no significant difference in recovery of contractile function between propofol and fentanyl as assessed by normalised preload recruitable work area (50±10 vs 47±16%), normalised systolic shortening (36±12 vs 48±14%) and peak left ventricular dP/dt (1665±276 vs 1846±151 mmHg.s^-1) at the end of reperfusion.
Conclusion : We conclude that at the concentration used in this study propofol shows no improvement in contractility during "stunning" when compared to fentanyl.     

Comparison of subhypnotic doses of thiopentone vs propofol on the incidence of postoperative nausea and vomiting following middle ear surgery

Background : Middle ear surgery is associated with a high incidence of emetic sequelae and propofol has been reported to have antiemetic activity in subhypnotic doses.
Methods : In a double-blind, randomized study, the patients received either thiopentone 1.0 mg.kg^-1 (n=26) or 0.5 mg.kg^-1 propofol (n=26) at the end of middle ear surgery under isoflurane-N₂O-fentanyl-vecuronium anaesthesia. Trained nurses, unaware of the group assignment, assessed postoperative nausea, retching and vomiting up to 24 h after the end of anaesthesia. Droperidol 10μg.kg^-1 was used as a "rescue" antiemetic.
Results : The main result was that the patients in the propofol group did not suffer from retching and vomiting (R&V) during the first 6 h, whereas these symptoms occurred in 46% ( P <0.001) of the patients in the thiopentone group. The patients in the propofol group needed significantly less droperidol during the first 24 h (mean number of doses 0.39 ± 0.57 (SD)) than the patients in the thiopentone group (1.35 ± 1.47, P <0.005). Treatment with propofol was a predictor for lowered incidence of R&V, as well as male gender and negative history of motion sickness.
Conclusion : Propofol at a subhypnotic dose of 0.5 mg.kg^-1 provides prophylaxis against retching and vomiting for the first 6 h postoperatively after middle ear surgery. The incidence of nausea was not reduced by propofol.     

Granisetron prevents nausea and vomiting during spinal anaesthesia for caesarean section

Background: Nausea and vomiting during spinal anaesthesia for caesarean section are common and unpleasant complications. This study was undertaken to evaluate the efficacy of granisetron, a selective 5-hydroxytryptamine type 3 receptor antagonist, for prophylactic treatment of nausea and vomiting in parturients undergoing nonemergent caesarean section under spinal anaesthesia.
Methods: In a randomized, double-blind, placebo-controlled trial, 100 patients, 21–38 years, received either placebo (saline) or granisetron at 3 different doses (20 μg · kg^-1, 40 μg · kg^-1 or 80 μg · kg^-1) (n=25 for each) intravenously immediately after clamping of the foetal umbilical cord. Nausea, vomiting and safety assessments were performed during spinal anaesthesia for caesarean section.
Results: The treatment groups were similar with regard to maternal characteristics and operative management. The incidence of nausea and vomiting was 64%, 52%, 14% and 12% after administration of placebo and granisetron in a dose of 20 μg · kg^-1, 40 μg · kg^-1 and 80 μg · kg^-1, respectively ( P <0.05; overall Fisher's exact probability test). No clinically important adverse effects were observed in any group.
Conclusions: Prophylactic use of granisetron in a minimum dose of 40 μg · kg^-1 is effective for preventing nausea and vomiting during spinal anaesthesia for caesarean section.
© Acta Anaesthesiologiat Scandinavica 42 (1998)     

Propofol influences the electroretinogram to a lesser degree than thiopentone

Background: The Electroretinogram (ERG) is used clinically to assess the function of retina. Anaesthetic agents are known to affect ERG, and as anaesthesia is often needed in children and uncooperative patients, knowledge about its effects is of clinical importance. Barbiturates selectively depress ERG components, and we compared thiopentone with propofol to assess if the latter preserved retinal function better.
Methods: Ten pigs, average weight 17 kg (SD ± 2 kg) were anaesthetized randomly with propofol 10 mg kg^-1 or thiopentone 30 mg kg^-1. Anaesthesia was maintained by 65% nitrous oxide in oxygen and continuous infusion of the induction agent, i.e. 10 mg kg^-1 h^-1 of propofol, or 10 mg kg^-1 h^-1 for the first hour, then 5 mg kg^-1 h^-1 of thiopentone, with doses being based on pilot studies. After an interval of one week the programme was repeated using the other agent. After 40 minutes dark-adaptation, responses to single flashes of graded intensities from a xenon flashlamp were recorded at five-minute intervals. The a- and b-wave amplitudes and implicit times (time to peak), and a-wave slopes were determined.
Results: The b-wave implicit time was significantly shorter during propofol anaesthesia than when using thiopentone. The effect was most pronounced at the lowest intensities (P < 0.01). No statistically significant differences were found in the amplitudes of the b-waves. The a-wave appeared at lower stimulus intensity (P < 0.05) and the a-wave slopes were significantly steeper (P < 0.01) during propofol anaesthesia.
Conclusion: Propofol accordingly appeared to preserve the photoreceptor response better than thiopentone, and may therefore be considered to be more suitable for ERG recordings than thiopentone.     

Effective dose of granisetron in the reduction of nausea and vomiting after breast surgery

Background: Prophylactic use of granisetron, a selective Shydroxytryptamine type 3 receptor antagonist, reduces the incidence of nausea and vomiting after breast surgery. This study was undertaken to determine the minimum effective dose of granisetron in the reduction of postoperative nausea and vomiting (PONV) in patients undergoing general anaesthesia for breast surgery.
Methods: In a randomized, double-blind manner, 120 female patients aged 42–66 years were assigned to receive either placebo (saline) or granisetron in a dose of 20 μg · kg^-1, 40 μg · kg^-1 and 80 μg · kg^-1 i.v. immediately before the induction of anaesthesia. A standard general anaesthetic technique was employed throughout. The POW and safety assessments were performed continuously during the first 24 h after anaesthesia.
Results: There were no significant differences among the groups with regard to patient demographics, surgical procedures, anaesthetics administered and analgesics given. The incidence of PONV was 47%, 43%, 17% and 17% after administration of placebo and granisetron 20 μg -kg^-1, 40 μg kg^-1 and 80 μg kg^-1, respectively. Granisetron 40 μg kg^-1 was as effective as 80 μ g - kg^-1 and both resulted in significant reductions of the incidence of PONV compared with placebo and granisetron 20 μg kg^-1 ( P < 0.05). No differences in the incidence of adverse events were observed among the groups.
Conclusion: Granisetron 40 μg · kg^-1 appears to be the minimum effective dose for reducing POW in patients undergoing general anaesthesia for breast surgery.     

Peroperative adenosine infusion reduces isoflurane concentrations during general anesthesia for shoulder surgery

Background: Adenosine (ADO), and stable analogs thereof, have been shown to exert antinociceptive action under experimental conditions in animals and in humans. The aim of this randomized double-blind placebo-controlled study was to evaluate if a low dose of intravenous (i.v.) ADO could reduce isoflurane requirements during joint-associated surgery, as an indication of antinociception in deep somatic pain.
Methods: Thirty-two patients, age 19–62 years, ASA I and II, scheduled for shoulder joint surgery, were assigned to receive an i.v. infusion of either adenosine, 80 μg kg^-1 min^-1, or placebo, during the surgical procedure. Anesthesia was maintained with isoflurane/N₂O/O₂ inhalation.
Results: The peroperative isoflurane concentration was significantly reduced at 50 minutes of surgery in the group receiving adenosine infusion. Also, the systolic blood pressure level was peroperatively more stable during adenosine infusion than during placebo. Other clinical parameters, such as pain, postoperative analgesic requirements and nausea, were not different between groups.
Conclusion: A peroperative infusion of a low dose of adenosine during shoulder joint surgery may reduce the peroperative isoflurane requirement.     

Influence of premedication with diazepam or morphine on the induction dose of eltanolone

Background : This study examined the influence of premedication with morphine or diazepam on the dose of eltanolone, a steroidal intravenous anaesthetic agent, required to induce anaesthesia.
Methods : Two hundred and sixteen patients, aged 18 to 65 years, were randomly assigned to receive premedication with diazepam 10 mg orally, morphine 10 mg intramuscularly, or placebo. The double-dummy technique was used to maintain blinding. Eltanolone 0.16-0.75 mg·kg^-1 was given intravenously over 20 s. At the commencement of injection patients were instructed to begin counting; if the patient ceased counting within 120 s and failed to respond to commands to continue, anaesthesia was considered to have been induced. The dose required to anaesthetise 50% of patients (ED₅₀) was determined by logistic regression.
Results : The ED₅₀ (95% confidence interval) of eltanolone in patients who received placebo premedication was 0.31 (0.27-0.34) mg · kg^-1. It was reduced slightly and nonsignificantly by premedication with diazepam, to 0.27 (0.24-0.30) mg · kg^-1, or morphine, to 0.26 (0.23-0.29) mg · kg^-1. Involuntary movement occurred in 65% of placebo premedicated patients. Its incidence was not significantly reduced by diazepam (57%), but was significantly ( P <0.001) reduced by morphine (37%). Morphine premedication was, however, associated with a significant ( P <0.01) increase in the incidence of apnoea (21%) compared to placebo premedicated patients (4%).
Conclusion : Premedication with diazepam or morphine had little influence on the dose of eltanolone required to induce anaesthesia.     

Oculocardiac reflex and postoperative vomiting in paediatric strabismus surgery. A randomised controlled trial comparing four anaesthetic techniques

Background : Oculocardiac reflex (OCR) and postoperative vomiting are major complications of paediatric strabismus surgery.
Methods : Children (3–16 yr) undergoing elective strabismus surgery as inpatients were randomly allocated to four anaesthetic techniques: (A) thiopentone induction and isoflurane maintenance; (B) as (A) plus ondansetron 5 mg · m^-2 iv; (C) propofol induction and maintenance; (D) as (C) plus lignocaine 2 mg · kg^-1 iv. All children received prophylactic atropine 0.02 mg · kg^-1 and alfentanil. Nitrous oxide was omitted.
Results : Data on 157 children were analysed. The cumulative incidence of vomiting within 6 and 24 h after surgery with thio-pentone-isoflurane was 26% and 46%, respectively. Adding ondansetron decreased the incidence to 8% and 33%, respectively. This improvement was significant within 6 h only; the number-needed-to-treat was 5.5 (95% CI 2.9–46). Propofol was not different from thiopentone-isoflurane. The addition of lignocaine to propofol was of no benefit. The risk of an OCR was significantly increased with propofol (incidence 40%) compared with isoflurane (14%); the number-needed-to-harm was 3.9 (95% CI 2.6–8).
Conclusions : Thiopental-isoflurane-air/O₂-alfentanil resulted in a moderate risk of vomiting. Adding ondansetron significantly decreased this risk, but 6 children have to be treated for one to benefit in the early postoperative period. Propofol and propofol-lignocaine showed no benefit on vomiting but significantly increased the risk of an OCR despite high-dose prophylactic atropine.     

Comparison of propofol/alfentanil anaesthesia with isoflurane/N2O/fentanyl anaesthesia for renal transplantation

Total intavenous anaesthesia (TIVA) with propofol and alfentanil was compared with balanced anaesthesia (BA) in 30 uraemic patients undergoing renal transplantation. TIVA (n=15) was induced with propofol and alfentanil and maintained with propofol and alfentanil infusions, which were started immediately after induction. Thereafter the infusion rates were adjusted as needed. Ventilation was with oxygen in air. BA (n= 15) was induced with thiopentone and fentanyl and maintained with isoflurane/N20/fentanyl. Vecuronium was used for muscle relaxation in both groups. Mean infusion rates for propofol and alfentanil were 10 1.8 mg kg^-1 h^-1 and 70 9 μg kg^-1 h^-1, respectively. To control hypertension during TIVA, larger amounts of propofol and alfentanil were needed and slower recovery was observed than in previous studies in ASA 1–2 patients. Also, significantly more vecuronium was needed during TIVA than during BA ( P < 0.05). The recovery parameters were similar in both groups, except for the occurrence of nausea, which was less after TIVA. In conclusion, TIVA had no clinical advantages over BA.     

Intravenous propofol vs thiamylal-isoflurane for caesarean section, comparative maternal and neonatal effects

Several studies on propofol (Diprivan) for induction of anaesthesia during caesarean section have demonstrated its safety, however, its safely during maintenance of anaesthesia is not yet fully evaluated.
The present study was undertaken to compare the maternal and neonatal effects of propofol or isoflurane in 74 term parturients undergoing primary or repeat caesarean section. Patients were randomly assigned to two groups, propofol group (n = 37) received propofol 1.5–2.5 mg·kg^-1 for induction followed by a continuous infusion of propofol of 0.05–0.2 mg 4mD kg^-1 · min^-1. The isoflurane group (n=37) received thiamylal 3–4 mg · kg^-1 for induction followed by isollurane 0.25–0.75% for maintenance. All patients had rapid sequence induction using suceinyl-choline and endotracheal intubation, 50% N₂O and O₂ were used in all patients until delivery. After delivery N₂O concentration was increased to 67% and intravenous butorphanol (Stadol) was given as needed. Patients in the propofol group had less hypertension after intubation ( P <0.05) and this was also of shorter duration compared to patients in the isoflurane group (5 min vs 10 min respectively). Maternal blood loss as well as intraoperative awareness and recovery time did not differ significantly between the two groups. Neonatal status as ascertained by Apgar scores, cord acid base status and the neurological and adaptive capacity scores (NACS) was equally good in both groups. It is concluded that propofol used for induction and maintenance of anaesthesia is a safe alternative to thiamylal/isoflurane for patients undergoing caesarean section and is associated with less hypertensive response during laryngoscopy and intubation.     

Propofol infusion anaesthesia and immune response in minor surgery

This study was set up to evaluate the effects of propofol infusion anaesthesia on immunological function in minor surgery. Twenty-seven patients (median age 51 years, ASA 1-2) scheduled for minor breast surgery were randomly assigned to two groups. Anaesthesia was induced in group 1 with propofol 2.5 mg.kg^-1 and maintained with propofol 12 mg.kg^-1.h^-1 and 30% O₂ in air, whereas in group 2 anaesthesia was induced with thiopentone 4 mg.kg^-1 and maintained with 70% N₂O in O₂. Fentanyl and vecuronium were used in both groups. The percentages of T cells (p < 0.001), B cells (p < 0.01) and memory T cells increased (p < 0.01) in both groups. T helper cell percentages increased in the propofol but not in the thiopentone group (p < 0.05). The percentages of natural killer cells decreased from pre-induction values in both groups (p < 0.001). No changes were seen in lymphocyte proliferative responses. Minor breast surgery under propofol or conventional combined anaesthesia had only minor effects on the immune response. The higher percentage of T helper cells after propofol anaesthesia compared to conventional combined anaesthesia is beneficial, but its clinical importance remains to be determined.     

Antinociceptive effect of perioperative adenosine infusion in abdominal hysterectomy

Background: Adenosine (ADO), and stable analogs thereof, have been shown to exert antinociceptive action in cutaneous and deep somatic pain under experimental and clinical conditions in animals and in humans. The aims of this randomized double-blind placebo-controlled study were to evaluate if a low dose of intravenous (i.v.) ADO could reduce the requirements of volatile anesthetic and postoperative opioid in connection to hysterectomy, where visceral nociception significantly contributes to pain.
Methods:
Forty-three women, age 32–65 years, ASA I and 11, scheduled for abdominal hysterectomy, were assigned to receive an i.v. infusion of either adenosine, 80 μg. kg^-1 min^-1, or placebo during surgery. Anesthesia was maintained with isoflurane (ISO)/N₂O/ O₂ inhalation. Postoperatively, a reduced dose of 40 μg. kg^-1. min^-1 was continued for 3 h.
Results: The end-tidal (ET-) IS0 was equal between groups before surgery. During surgery, the IS0 requirement was increased, compared to the preoperative level, in the placebo group, while the requirement declined in the ADO group. The overall IS0 requirement in the ADO group was reduced by 36% (P<0.002). The first 24 h postoperative opioid requirement, with equal resting pain in both groups, was 18% ( P < 0.05)lower in the ADO group.
Conclusion: A low dose of perioperative adenosine infusion in abdominal hysterectomy reduces the requirements of volatile anesthetic and postoperative opioid analgesic.     

Nausea and vomiting after major arthroplasty with spinal anaesthesia including morphine: a randomised trial of subhypnotic propofol infusion as prophylaxis

Background : Postoperative nausea and vomiting (PONV) following major arthroplasty with spinal anaesthesia and intrathecal morphine is reported in 45–74% of patients. This randomised, double-blind, placebo-controlled trial was undertaken to determine whether a subhypnotic infusion of propofol has a prophylactic antiemetic effect in this patient population.
Methods : 82 patients undergoing hip or knee replacement under subarachnoid bupivacaine anaesthesia plus morphine 0.25 mg were randomised at the end of surgery to receive either propofol 30 mg · h^-1 or fat emulsion (Intralipid®) 3 ml · h^-1 for 20 h postoperatively. Blinded observers recorded episodes of nausea, vorniting and pruritus.
Results : PONV in the intervention group was 40% vs 59% in the controls (P=0.1, not significant). Pruritus occurred in 34%, with a similar rate in both groups.
Conclusion : These results suggest that routine use of postoperative, subhypnotic propofol infusion as PONV prophylaxis is not justified in this patient population.     

Lack of effect of flumazenil on the reversal of propofol anaesthesia

Propofol, like the benzodiazepines, activates the GABA_A receptor-chloride ionophore complex; they potentiate one another. Since neither pharmacodynamic nor pharmacokinetic data concerning drug interaction between flumazenil and propofol is available, and especially considering the relationship of binding sites, flumazenil, the antagonist of benzodiazepines, was investigated to determine its effect upon recovery from propofol anaesthesia. Forty women receiving dilatation and curettage procedures were included in this double-blind test. After 50 μg fentanyl, propofol 2 mg · kg^-1 was injected for induction and followed by infusion at the rate of 15 mg · kg^-1 · hr^-1. After the operation, patients were given normal saline (Group A) or flumazenil 10 μg · kg^-1 (Group B) randomly.
Recovery time in Group A was 15.2±5.1 min and Group B 15.8±4.8 min. Propofol concentrations at the end of infusion were 4.17±1.33 μg ·ml^-1 (Group A) and 4.03±1.45 μg · ml^-1 (Group B); these then declined to 1.22±0.17 μg · ml^-1 (Group A) and 1.18±0.15 μg · ml^-1 (Group B) when patients were able to open their eyes on command. No significant differences were found between the groups based on propofol concentrations and recovery time, nor did haemodynamic changes differ between them after administration of reversal agents. It was concluded that flumazenil 10 μg · ml^-1 does not influence recovery from propofol anaesthesia.     

Isosorbide dinitrate does not interfere with heparin anticoagulation:

The possible nitrate-induced heparin resistance was studied intraoperatively in 40 patients undergoing coronary artery bypass grafting. The patients were randomized to receive a continuous infusion of placebo, nitroglycerin (0.5 μg kg^-1 min^-1) or isosorbide dinitrate (0.5 or 2.5 μg kg^-1 min^-1). After the infusion had been administered, prior to the institution of cardiopulmonary bypass, for at least 60 min, porcine intestine heparin 300 I.U. kg^-1 (as divided in two consecutive doses of 100 and 200 I.U. kg^-1, respectively) was administered to achieve systemic anticoagulation. Activated coagulation time values and plasma heparin anti-X_a activity showed no significant differences between the groups before and after the administration of heparin. It is concluded that in doses given in the present study, organic nitrates do not interfere with the anticoagulation effect of large doses of heparin required for the conduction of cardiopulmonary bypass.     

Topographical analysis of the EEG effects of a subconvulsive dose of lidocaine in healthy volunteers

Background: The purpose of the present study was to assess the effects of intravenous lidocaine on spatial changes of electroen-cephalographic power and on psychomotoric status in conscious volunteers.
Methods: In 11 healthy volunteers lidocaine (2-min bolus, 100 mg; 15-min infusion, 40 μg kg^-1 min^-1) or placebo were given intravenously in a randomized, single-blinded, two-way crossover study. Haemodynamics and lidocaine plasma concentrations were measured at baseline and within a period of 30 min following bolus injection. Vigilance and emotional status were tested using visual analogue scales (VAS). Toxic CNS effects were evaluated by a questionnaire. The raw EEG (17 leads, reference C_z) and computed power spectra were continuously recorded.
Results: The chosen lidocaine dosage led to nearly constant plasma concentrations (unbound lidocaine 2.5 min and 15 min after bolus 0.36±0.14 μg/ml and 0.30±0.06 μg/ml, respectively [mean±SD]). The placebo caused no symptoms, changes in VAS-scores or EEG-parameters. Lidocaine induced pronounced subjective symptoms and significant increases in delta activity for 15 min, most dominant at the frontotemporal and occipital leads (max. +219% O₁). Frontal and occipital beta1 and beta2 power (max. +131% and +124% at O₁, respectively) was immediately increased after the bolus injection. No EEG changes occurred at central region C_z, and no interhemispheric EEG differences were noted. Theta, alphal, and alpha2 power remained unchanged.
Conclusion: The current data demonstrate simultaneous changes in psychomotoric status as well as delta and beta spectral power during lidocaine infusion. These data could be an indication that the pronounced frontotemporal and occipital EEG changes are the electroencephalographic expression of subjective sensations.     

Propofol–nitrous oxide versus thiopentone–isoflurane–nitrous oxide anaesthesia for uvulopalatopharyngoplasty in patients with sleep apnea

A randomized prospective study was performed to compare the recovery in 41 patients undergoing uvulopalatopharyngoplasty (UPPP) with either propofol-nitrous oxide-fentanyl or thiopentone-isoflurane-nitrous oxide-fentanyl anaesthesia. The patients were referred to UPPP after examination including polysomnography and otorhinolaryngological examination. The propofol group received propofol 2 mg·kg^-1 for induction followed by an infusion of 10 mg·kg^-1·h^-1 after intubation. The thiopentone-isofiurane group received 5 mg·kg^-1 of thiopentone for induction followed by isoflurane (0.5–2%) after intubation. Other medication was similar in both groups. In the propofol group the patients had a significantly better oxygen saturation during the first postoperative hour ( P < 0.05), and a higher rate of breathing ( P < 0.05), indicating a more rapid recovery of the physiologic control of breathing. Pain as measured by visual analogue score was lower ( P < 0.05) during the second postoperative hour compared with the isoflurane group. Apneic episodes occurred with similar frequency in both groups, and they were related to the severity of obstructive sleep apnea (OSA). We conclude that propofol is preferable to thiopentone-isofiurane in UPPP operations, because physiologic respiratory control recovers faster and postoperative pain is less intense.