A comparison of the effect on gastric emptying of propofol or dexmedetomidine in critically ill patients: preliminary study

BACKGROUND: Propofol and dexmedetomidine are widely used for sedation in the intensive care unit yet there are limited data on its effects on gastric motility. In our preliminary study, we examined whether or not any effect of propofol and dexmedetomidine on gastric emptying is preserved in critically ill patients. METHODS: Twenty-four critically ill, enterally fed adult patients each received enteral feeding via a nasogastric tube at 50 mL h-1 throughout the 5-h study period. Either propofol 2 mg kg-1 h-1 (n = 12, Group P) or dexmedetomidine 0.2 microg kg-1 h- (n = 12, Group D) was given intravenously over 5 h. Gastric motility was measured indirectly by analysis of the absorption over time of 1.5 g of paracetamol administered into the stomach at the start of the study period. At the beginning and end of the study, residual gastric volume and pH of residual gastric fluid were measured. RESULTS: Gastric residual volume measured at the end of propofol infusion (19.33 +/- 11.33) was found to be higher when compared with the volume measured before infusion (11.33 +/- 4.84) and after dexmedetomidine infusion (9.17 +/- 4.54). But, there was no difference between groups in gastric emptying time (AUC120 894.53 +/- 499.39 vs. 1113.46 +/- 598.09 propofol and dexmedetomidine groups, respectively). CONCLUSION: In our study, gastric residual volume measured at the end of propofol infusion was found to be higher when compared with the volume measured before infusion and after dexmedetomidine infusion. There was no difference between groups in gastric emptying time.     

Propofol and gastric effects of morphine

OBJECTIVE: The purpose of this study was to evaluate whether propofol abolishes morphine-induced effects on gastric emptying and gastric tone. METHOD: The study was carried out before anesthesia in 40 patients (ASA I-II). Gastric tone was measured in 20 patients by an electronic barostat. Volume changes were thereby registered continuously in an intragastric flaccid bag with a constant preset pressure. All patients received i.v. morphine 0.1 mg x kg(-1) before the measurements and, in a randomized order, 10 of the patients also received a bolus dose of propofol 1 mg. kg-1 before morphine. Gastric emptying was studied with the paracetamol method in 20 patients. All patients received morphine 0.1 mg x kg(-1) i.v. 10 min before oral ingestion of 1.5 g paracetamol in 200 ml water and, in a randomized order, 10 of the patients also received propofol, a bolus dose of 0.3 mg x kg(-1) before morphine, followed by an infusion of 1 mg x kg(-1) x h(-1) during the whole study (2 h). RESULTS: The volume in the intragastric bag increased in all patients receiving morphine without propofol. In the group that received propofol before morphine, the volume in the intragastric bag decreased in all patients. The volume differences between the groups were statistically significant (P<0.01). There were no statistically significant differences of the AUC60, Cmax and Tmax of serum paracetamol concentrations between the morphine and propofol-morphine groups. CONCLUSION: Propofol did not abolish morphine-induced delay of gastric emptying even if propofol abolished the decrease of gastric tone induced by morphine.     

Effect of the association propofol-alfentanil on bronchial resistances in asthmatic patients

The bronchial resistances in 17 patients scheduled for ENT surgery were studied during general anaesthesia carried out with propofol and alfentanil. There were nine controls, all free from any allergic pathology. The other eight had bronchial hyperreactivity, with clinical asthma (one or two crises a month) treated with bronchodilators. Two had a complete Fernand-Widal syndrome, and the remaining six documented allergic asthma. All the patients were premedicated with hydroxyzine 2 mg.kg-1 orally on the eve of surgery, and two hours beforehand. Those patients who were on bronchodilators were given their drugs as usual with the premedication. Because bronchial resistances were measured with the patient breathing spontaneously (forced oscillation technique), induction was carried out in two steps, first with propofol 1.5 mg.kg-1, followed, two minutes later, by alfentanil 7 micrograms.kg-1. Once the bronchial resistances had been assessed the patient was given a further 2 mg.kg-1 dose of propofol, and alfentanil 40 micrograms.kg-1. The patient was then intubated, and anaesthesia maintained with propofol 9 mg.kg-1.h-1, and alfentanil 15 micrograms.kg-1 every fifteen minutes. In all, bronchial resistances were measured on the day before surgery, after premedication but before the patient had been given any anaesthetic drug, two minutes after the first injection of propofol, two minutes after the first injection of alfentanil, and after extubation. There were no significant differences between the two groups. Despite the small number of patients included in this study, it would seem that hydroxyzine, propofol and alfentanil may be used safely in patients with hyperreactive bronchi.     

The use of low-dose rocuronium to facilitate laryngeal mask airway insertion

In this two-phase study, the efficacy of low-dose rocuronium to facilitate laryngeal mask airway (LMA) insertion was evaluated. First, the onset time of 100, 150 and 300 micrograms.kg-1 rocuronium was determined using mechanomyography in three groups of patients (n = 10 in each) anaesthetized with propofol-fentanyl-nitrous oxide. In the second part, 100, 150 or 300 micrograms.kg-1 rocuronium or placebo was administered randomly to four groups of patients (n = 50 in each) in a double-blind manner. Following this, anaesthesia was induced with propofol 2.5 mg.kg-1. Patients in the group of 300 micrograms.kg-1 rocuronium or placebo received propofol after 1.5 min. Patients in the group of 100 or 150 micrograms.kg-1 rocuronium received propofol after 3 min. The LMA was inserted 90 sec later. Immediately before the induction of anaesthesia, patients were questioned about the symptoms of neuromuscular block. In phase 1, onset times were 180 sec (SD 41), 191 sec (59) and 89 sec (34), respectively. In phase 2, insertion of the LMA was graded as easy in 90.6% of patients receiving rocuronium, compared with 42% of patients who had only propofol (P < 0.05). Rocuronium improved the overall ease of LMA insertion. LMA insertion was graded easy in 80% of patients who received 100 micrograms.kg-1 rocuronium. The incidence of unpleasant effects was greatest with 300 micrograms.kg-1 rocuronium. The optimal dose needed to facilitate LMA insertion with minimal unpleasant effects appeared to be 100 micrograms.kg-1 rocuronium.     

Total intravenous anaesthesia with propofol,alfentanil, and oxygen-air: three different dosage schemes

Three different dosage schemes of propofol infusions combined with a fixed-rate alfentanil infusion were investigated in total intravenous anaesthesia. In 30 premedicated patients, divided at random into three groups, anaesthesia was induced with propofol 2 mg.kg-1 immediately followed by an alfentanil infusion 10 micrograms.kg-1.min-1 as a loading dose which was decreased after ten minutes to a maintenance dose of 1 microgram.kg-1.min-1. Vecuronium bromide 0.1 mg.kg-1 was used as the muscle relaxant. After induction of anaesthesia a propofol infusion 2 mg.kg-1.hr-1 was started in group A, 3 mg.kg-1.hr-1 in group B and 4 mg.kg-1 hr-1 in group C. At signs of light anaesthesia supplementary bolus doses of 20 mg propofol and 1 mg alfentanil were given. The patients' lungs were ventilated with air-oxygen (FIO2 0.35). The mean systolic and diastolic blood pressures showed no statistical significant differences between the three groups. A significant (P less than 0.01) decrease of the mean systolic and diastolic blood pressures was present after induction of anaesthesia and tracheal intubation. Recovery was uneventful in all but one patient, who had ventilatory depression that responded to naloxone (0.2 mg IV). Awareness did not occur in any patient. The only difference between the three groups was the higher number of supplementary bolus doses of propofol and alfentanil needed in group A (P less than 0.01). In total intravenous anaesthesia propofol 3 and 4 mg.kg-1.hr-1 as a maintenance dose combined with a two-step fixed-rate alfentanil infusion provided smooth anaesthesia and uneventful rapid recovery.     

Disposition of propofol infusions for caesarean section

The disposition of propofol was studied in women undergoing elective Caesarean section. Indices of maternal recovery and neonatal assessment were correlated with venous concentrations of propofol. After induction of anaesthesia with propofol 2.0 mg.kg-1, ten patients received propofol 6 mg.kg-1.hr-1 with nitrous oxide 50 per cent in oxygen (low group) and nine were given propofol 9 mg.kg-1.hr-1 with oxygen 100 per cent (high group). Pharmacokinetic variables were similar between the groups. The mean +/- SD Vss = 2.38 +/- 1.16 L.kg-1, Cl = 39.2 +/- 9.75 ml.min-1.kg-1 and t1/2 beta = 126 +/- 68.7 min. At the time of delivery (8-16 min), the concentration of propofol ranged from 1.91-3.82 micrograms.ml-1 in the maternal vein (MV), 1.00-2.00 micrograms.ml-1 in the umbilical vein (UV) and 0.53-1.66 micrograms.ml-1 in the umbilical artery (UA). Neonates with high UV concentrations of propofol at delivery had lower neurologic and adaptive capacity scores 15 minutes later. The concentrations of propofol were similar between groups during the infusion but they declined at a faster rate in the low group postoperatively. Maternal recovery times did not depend on the total dose of propofol but the concentration of propofol at the time of eye opening was greater in the high group than the low group (1.74 +/- 0.51 vs 1.24 +/- 0.32 micrograms.ml-1, P less than 0.01). The rapid placental transfer of propofol during Caesarean section requires propofol infusions to be given cautiously, especially when induction to delivery times are long.     

Total intravenous anaesthesia with propofol or etomidate

In combination with fentanyl, propofol was compared with etomidate for total intravenous anaesthesia in 21 women (ASA Grades I-II) admitted for elective hysterectomy. They received either propofol (bolus 1.5 mg kg-1, infusion 9 mg kg-1 h-1 for 10 min thereafter 6 mg kg-1 h-1) or etomidate (bolus 0.10 mg kg-1, infusion 3 mg kg-1 h-1 reduced to 0.6 mg kg-1 h-1). Fentanyl 10 micrograms kg-1 was given for induction followed by an infusion of 30 micrograms kg-1 h-1 for 10 min reduced to 6 micrograms kg-1 h-1 for the first hour and successively reduced over time. Induction was smooth and maintenance easy to manage in both groups. There was no difference in time from end of infusion until extubation, but the time until the patients could report their date of birth was significantly shorter in the propofol group. Nausea and vomiting were more pronounced in the etomidate group, and mental side-effects were only seen after etomidate. After 3 months, more patients in the etomidate group complained of reduced power of concentration. We conclude that total intravenous anaesthesia with either propofol or etomidate is equally easy to manage, but in the recovery situation propofol was advantageous in time and quality.     

Propofol in urological endoscopy in elderly patients. Comparison with methohexital

Twenty patients undergoing cystoscopy (group A) and forty patients undergoing transurethral resection (group B), aged more than 65 years, were anaesthetized. Duration of anaesthesia was less than 15 min for cystoscopy, and more than 30 min for transurethral resection. No premedication was given. The patients were ASA I or ASA II. Group A patients were allocated randomly to receive either 1.5 mg . kg-1 propofol (n = 10) or 2 mg . kg-1 methohexitone (n = 10) for induction of anaesthesia. Anaesthesia was maintained using incremental doses of propofol or methohexitone and 60% N2O with a face-mask. Forty group B patients undergoing transurethral resection were randomly assigned to four equal groups (PB: propofol 1.5 mg . kg-1; MB: methohexitone 2 mg . kg-1; PF: propofol and 1.5 micrograms . kg-1 fentanyl; PFV: propofol, 2 micrograms . kg-1 fentanyl and 0.1 mg . kg-1 vecuronium). Suxamethonium (1 mg . kg-1; groups PB, MB and PF) and vecuronium (0.1 mg . kg-1; group PFV) were given to facilitate endotracheal intubation. Anaesthesia was maintained by infusion of propofol or methohexitone, using a calibrated pump started immediately after intubation. Ventilation was controlled only in group PFV. Induction with 1.5 mg . kg-1 propofol resulted in stopping counting after 62 s and loss of the eye-lash reflex after 84 s versus 47 and 67 s respectively with methohexitone. The anaesthesist's assessment was favourable for cystoscopy with propofol and methohexitone; recovery times were similar for the two drugs in cystoscopy lasting less than 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of methohexitone and propofol with or without alfentanil on seizure duration and recovery in electroconvulsive therapy

We have studied the effects of methohexitone and propofol with and without alfentanil on seizure duration and recovery in this observer- blinded, prospective, randomized, crossover study involving 24 patients undergoing electroconvulsive therapy (ECT). Each patient had four treatment sessions, and received the following four i.v. regimens in random order: methohexitone 0.75 mg kg-1, methohexitone 0.50 mg kg-1 and alfentanil 10 micrograms kg-1, propofol 0.75 mg kg-1, propofol 0.50 mg kg-1 and alfentanil 10 micrograms kg-1. Additional methohexitone or propofol was given as needed in 10-20-mg increments until loss of consciousness. Suxamethonium 1.0 mg kg-1 i.v. was given for muscular paralysis. Mean motor and EEG seizure durations were longer with methohexitone-alfentanil (44.7 (SD 15.0) and 70.5 (29.7) s) than with methohexitone (37.6 (12.6) and 52.6 (15.3) s) and similarly, seizures were longer with propofol-alfentanil (36.8 (15.2) and 54.5 (20.9) s) than with propofol alone (27.2 (11.9) and 39.2 (3.9) s). Seizures were longest with methohexitone-alfentanil and shortest with propofol. Recovery time was statistically shorter in patients receiving propofol compared with methohexitone-alfentanil and methohexitone alone. Alfentanil with a reduced dose of methohexitone or propofol provided unconsciousness and increased seizure duration in patients undergoing ECT. We conclude that the combination of methohexitone with alfentanil is a good regimen for ECT, especially for patients with short seizure duration.      

Ambulatory anesthesia and induced abortion. Comparative study of propofol-alfentanyl and ketamine-midazolam combinations

The use of propofol alone or with alfentanil in the day-case anaesthesia for abortion was compared with that of ketamine with midazolam. Two hundred young women were assigned to two successive series of two groups each. The four groups were: group 1 (2 mg . kg-1 propofol only); group II (0.5 mg . kg-1 ketamine with 0.25 mg . kg-1 midazolam); group III (2 mg . kg-1 propofol with 4 micrograms . kg-1 alfentanil); group IV (1 mg . kg-1 ketamine with 0.1 mg . kg-1 midazolam). All the patients were premedicated one hour before anaesthesia with 0.25 mg . kg-1 midazolam orally. All the patients were asleep at the end of the propofol injection (60 s), and 10 to 15 s later for the ketamine-midazolam groups. The haemodynamic parameters did not vary much during induction with ketamine-midazolam. In the propofol groups, the heart rate remained steady, with an 8 to 12% fall in blood pressure. A fall of the mandible was seen in 40 and 84% of the patients in the propofol groups, with a short apnoea in 32 and 48% of these same patients. Clinical recovery was very quick, less than 12 min for all groups. The four psychomotor and sensory tests were carried out at the 30th min by 95% of the patients in the propofol groups, whereas only 50% of those in the ketamine-midazolam groups did so. Speed and quality were significantly better in the propofol groups. The most frequent adverse effect of propofol was pain during injection in 32 and 14% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Recovery characteristics using isoflurane or propofol for maintenance of anaesthesia: a double-blind controlled trial

We studied 114 female patients (ASA 1 or 2) who were within 20% of ideal body weight and who were scheduled to undergo gynaecological laparoscopy which required supplementation with an opioid (groups IA and PA), or dental procedures which did not require opioid supplementation (groups IO and PO). A computerised package of psychomotor tests was performed before surgery. Anaesthesia was induced with propofol 2.5 mg.kg-1 and all patients received atracurium 0.3 mg.kg-1 and 67% nitrous oxide in oxygen. Patients in group IA received isoflurane 1% (inspired), and alfentanil 10 micrograms.kg-1 as a bolus and 10 micrograms.kg-1.h-1 as an infusion. Patients in group PA received propofol 9 mg.kg-1.h-1 as an infusion, decreasing to 6 mg.kg-1.h-1 after 15 min, together with alfentanil 10 micrograms.kg-1.h-1. Patients in groups IO and PO received isoflurane and propofol in the regimens described for groups IA and PA, but without alfentanil. Recovery was assessed by a blinded observer who recorded times to awakening (eye opening) and orientation (giving date of birth), and who repeated the psychomotor tests at 1, 3 and 5 h. Linear analogue scales of mood, nausea and pain were obtained and other side effects were noted in the succeeding 48 h. A matched control group of 25 females (who were not anaesthetised) underwent psychomotor testing on four occasions in order to assess the 'learning effect' of repeated recovery testing. The analysis of recovery tests did not assume a normal distribution.(ABSTRACT TRUNCATED AT 250 WORDS)     

Injection pain, cardiovascular changes and recovery following induction of anaesthesia with propofol in combination with alfentanil or lignocaine in children

The effect of pretreatment with alfentanil 10 (Alf10), 15 (Alf15) or 20 (Alf20) micrograms.kg-1 on reducing injection pain caused by propofol was compared with lignocaine 10 mg mixed with propofol (Lign). This double-blind, double-dummy and randomized study included 100 children with a mean age of 4.3 +/- 0.6 years, 25 children in each group, undergoing minor otolaryngological surgery. The children were premedicated orally with midazolam 0.5 mg.kg-1 and atropine 0.03 mg.kg-1. Injection pain occurred in 4% in the Lign group. The corresponding figures were 40, 16 and 20% in the Alf10, Alf15 and Alf20 groups, respectively. Both 1% lignocaine 10 mg and alfentanil 15 micrograms.kg-1 reduced injection pain significantly compared with alfentanil 10 micrograms.kg-1. Pretreatment with alfentanil significantly diminished haemodynamic responses to tracheal intubation. Furthermore, the concomitant use of alfentanil and propofol caused transient severe bradycardia and a significant decrease in heart rate after laryngoscopy.     

Conditions for laryngeal mask insertionA comparison of propofol versus sevoflurane with or without alfentanil

One hundred unpremedicated ASA 1 or 2 patients scheduled for elective surgery were divided equally into four groups and recruited into this prospective, randomised parallel groups study. Induction was with propofol 2.5 mg.kg-1 or vital-capacity breath induction with sevoflurane (> 7% in the inspiratory gas) in 65% nitrous oxide and oxygen, or gaseous induction with sevoflurane plus alfentanil 5 micrograms.kg-1 or propofol 2.5 mg.kg-1 and alfentanil 5 micrograms.kg-1. The conditions for laryngeal mask insertion were assessed and graded on a three-point scale using six variables. The overall condition for laryngeal mask insertion was assessed as excellent, satisfactory or poor on the basis of total score in each group. Excellent or satisfactory conditions were observed in 25 (100%) patients in the sevoflurane-alfentanil group, 22 (88%) in the propofol-alfentanil group and 16 (64%) patients each in the propofol and sevoflurane groups (p < 0.001). A sevoflurane-alfentanil combination provides better conditions for laryngeal mask insertion when compared with sevoflurane alone, or a propofol-alfentanil combination.     

Midazolam-flumazenil vs. propofol in ambulatory ENT endoscopic procedures.

Two total intravenous anaesthesia techniques were compared in an open study of 80 ambulatory patients undergoing ENT endoscopic procedures randomly assigned to two groups: Group I midazolam-flumazenil n = 40, Group II propofol n = 40. The mean doses including induction were 0.75 +/- 0.31 mg kg-1 h-1 for midazolam and 171 +/- 64 micrograms kg-1 min-1 for propofol for 46.3 +/- 17.7 min and 50.3 +/- 24.8 min respectively. At the end of the procedure flumazenil 8.1 +/- 1.9 micrograms kg-1 was administered to Group I patients followed by a flumazenil continuous infusion at a minimal arousal rate (MAR) of 0.24 +/- 0.1 micrograms kg-1 min-1, and propofol discontinued in Group II patients. Baseline mean arterial pressure (MAP) and heart rate (HR) were similar in both groups and remained so during the procedure and recovery. In patients with cardiovascular disease, large variations (greater than or equal to 40% of baseline values) occurred more frequently in the propofol group whereas large variations in patients with no cardiovascular disease occurred more frequently in the midazolam group (P less than 0.05). Early recovery was more rapid after midazolam (P less than 0.05) whereas late criteria for recovery (maze and ambulation tests) were met more rapidly after propofol (P less than 0.05). It is concluded that with the midazolam-flumazenil sequence, early recovery is faster and haemodynamic stability better maintained in poor cardiovascular risk patients, whereas with propofol, street-fitness is more rapidly obtained, and haemodynamic stability better maintained in good risk patients.     

Effects of premedication on dose requirements for propofol: comparison of clonidine and hydroxyzine

The influence of a single dose of clonidine (5 micrograms kg-1) or hydroxyzine (1 mg kg-1) on intraoperative propofol requirements was determined in 28 male patients (ASA I) undergoing elective orthopaedic surgery. Patients were randomly allocated to receive either clonidine or hydroxyzine orally 2 h before induction of anaesthesia. After a loading dose of propofol (2.5 mg kg-1), mivacurium (0.2 mg kg-1) and alfentanil (15 micrograms kg-1), anaesthesia was maintained with a standardized propofol infusion supplemented with nitrous oxide (66%) in oxygen. During surgery, additional propofol boluses (1 mg kg-1) were administered when heart rate or mean arterial pressure increased by more than 10% compared with preinduction values. The clonidine group demonstrated a 14.5% decrease in total propofol requirements (P < 0.05) and a 52.2% reduction in additional propofol boluses (P < 0.02) in comparison with the hydroxyzine group. intraoperative heart rate and mean arterial pressure were significantly lower in the clonidine group but no patients needed treatment with ephedrine for hypotension or bradycardia. Recovery of psychomotor function and discharge from the recovery room were not delayed in the clonidine group. This study indicates that 5 micrograms kg-1 clonidine given as premedication in ASA I patients reduces intraoperative propofol requirements in comparison with 1 mg kg-1 hydroxyzine without inducing adverse effects on recovery or haemodynamic stability.      

Assessment of intubating conditions in adults after induction with propofol and varying doses of remifentanil

We have assessed intubating conditions in three groups of 60 ASA I or II patients after induction of anaesthesia with propofol 2 mg kg-1 and remifentanil 0.5, 1.0 or 2.0 micrograms kg-1. Tracheal intubation was graded according to ease of laryn-goscopy, position of the vocal cords, coughing, jaw relaxation and movement of the limbs. Intubation was successful in 80%, 90% and 100% of patients after remifentanil 0.5, 1.0 or 2.0 micrograms kg-1, respectively. Overall intubating conditions were regarded as acceptable in 20%, 50% and 80% of patients, respectively. All three groups had a decrease in arterial pressure after induction but there was no difference between groups. The decrease in arterial pressure was not regarded as clinically significant. Intubating conditions were best after induction with remifentanil 2 micrograms kg and propofol 2 mg kg-1.      

Influence of induction technique on intubating conditions after rocuronium in adults: comparison with rapid-sequence induction using thiopentone and suxamethonium

We have assessed the effect of anaesthetic technique on intubating conditions after rocuronium 0.6 mg kg-1 in four groups (n = 25 each) of unpremedicated patients in whom anaesthesia was induced with either thiopentone 5 mg kg-1 or propofol 2.5 mg kg-1 alone, or supplemented with alfentanil 20 micrograms kg-1. Fifty control patients were anaesthetized with thiopentone followed by suxamethonium. Laryngoscopy was commenced at 45 s. Overall intubating conditions after rocuronium were similar to those after suxamethonium (good and excellent > or = 96%) only when alfentanil was part of the induction regimen. However, intubation time was similar in all five groups and averaged 55 (SD 3.2) s, and the tube could be passed through open vocal cords within 70 s. After rocuronium the response of the diaphragm to intubation was more pronounced in the two groups of patients not receiving alfentanil (P < 0.0001) and in patients anaesthetized using propofol with alfentanil (P < 0.01) than in the control group. Opioids (in doses equivalent to alfentanil 20 micrograms kg-1) constitute an integral part of an induction regimen containing rocuronium 0.6 mg kg-1, regardless of whether or not thiopentone or propofol is used, in order to achieve overall intubating conditions similar to those after suxamethonium.      

Comparaison de l’incidence sur le saignement de deux techniques anesthésiques midazolam-alfentanil versus propofol-alfentanil lors de la cure d’otospongiose

This study was performed to compare the incidence of bleeding associated with two anaesthetic techniques during otolaryngological microsurgery. Twenty-eight venous interpositions for otospongiosis have been carried out at random either under local anaesthesia combined with light sedation (midazolam 0.1 mg.kg-1 and alfentanil 0 micrograms.kg-1) or using general anaesthesia (propofol 2.5 mg.kg-1, then 9 mg.kg-1.hr-1 and alfentanil 30 micrograms.kg-1, then 15 micrograms.kg-1). The patients' lungs were mechanically ventilated. Every ten minutes, heart rate, arterial blood pressure and FETCO2 were observed. Bleeding was assessed on a four-point scale and evaluated according to its duration and the annoyance that it caused. General anaesthesia was clinically better tolerated. Heart rate and arterial blood pressure were lower than with general anaesthesia. The end-expiratory CO2 was 4.7 +/- 0.2 per cent. Bleeding was less frequent, lasted less time, but when it occurred the surgical disturbance was identical in the two groups. General anaesthesia produced a less bloody operating field and local anaesthesia required the cooperation of the patient.     

Relaxant effect of propofol on the airway in dogs

Propofol has been suggested to produce airway relaxant effects in vivo, although the mechanism is unclear. We have evaluated the bronchodilating effect of propofol using a direct visualization method with a superfine fibreoptic bronchoscope. We studied 21 mongrel dogs anaesthetized with pentobarbital 30 mg kg-1 i.v. and pancuronium 0.2 mg kg-1 h-1. The animals were allocated randomly to one of three groups (n = 7 in each): propofol group, atropine-propofol group and histamine- propofol group. The trachea was intubated using a tracheal tube that had a second lumen for insertion of the bronchoscope to monitor continuously bronchial cross-sectional area (BCA). BCA was measured using the NIH Image program. In the propofol group, dogs were given the following doses of propofol at 10-min intervals: 0 (saline), 0.2, 2.0 and 20 mg kg-1 i.v. In the atropine-propofol group, saline, atropine 0.2 mg kg-1 and propofol 20 mg kg-1 were given at 10-min intervals. In the histamine-propofol group, bronchoconstriction was elicited with histamine 10 micrograms kg-1 and 500 micrograms kg-1 h-1 until the end of the experiment. Thirty minutes after the start of infusion of histamine, propofol (0, 0.2, 2.0 and 20 mg kg-1) was administered. Changes in BCA were expressed as percentage of basal area. Histamine decreased BCA by 39.2 (SEM 5.4%). Propofol increased significantly basal and histamine-decreased BCA in a dose-dependent manner by 18.4 (4.5%) and 15.8 (4.9%), respectively after 20 mg kg-1 i.v. However, propofol following atropine i.v. did not increase BCA (129.9 (8.2)% after atropine vs 125.7 (8.9)% after propofol). Therefore, the relaxant effect of propofol may be a result of reduction in vagal tone.      

A comparison of fentanyl and buprenorphine in total intravenous anesthesia using propofol during spinal surgery

A retrospective study was performed to compare the hemodynamic effect and postoperative pain relief of fentanyl (Group F, n = 11) and buprenorphine (Group B, n = 11) in total intravenous anesthesia (TIVA) using propofol during spinal surgery. All patients were premedicated with midazolam (3-5 mg) i.m. Anesthesia was maintained with propofol infusion, and increments of fentanyl or single dose of buprenorphine with 40% oxygen in air. Total doses of fentanyl and buprenorphine were 7.6 +/- 1.0 micrograms.kg-1 and 2.0 +/- 0.4 micrograms.kg-1, respectively. Maintenance doses of propofol (Group F: 5.5 +/- 0.8 mg.kg-1.h-1, Group B: 5.9 +/- 1.1 mg.kg-1.h-1) and vecuronium were not significantly different. Mean arterial pressures from 2 hours after incision to the end of surgery were elevated significantly in Group F than in Group B. Recovery time (Group F 12.5 +/- 6.1 min vs Group B 11.8 +/- 6.1 min) and extubation time (Group F 19.5 +/- 10.3 min vs Group B 15.0 +/- 7.0 min) were not different. At the end of anesthesia, seven patients in Group F and one patient in Group B (P < 0.01) complained of severe pain. All patients in Group F, and only two in Group B (P < 0.02) received analgesics within 20 hours. Neither nausea nor respiratory depression was found in both groups. This study suggests that buprenorphine would provide a more stable hemodynamic state and better postoperative pain relief than fentanyl in TIVA using propofol.