Effects of propofol on intraocular pressure in surgery of strabismus in children

Propofol was assessed for eye surgery in 20 children. ASA group I or II, 2-14 year-old, randomly assigned to 2 equal groups. Premedication, analgesia and muscle paralysis were similar in both groups. Group P patients were given an induction dose of 4 mg.kg-1 propofol, followed by an infusion of 15 mg.kg-1.h-1 for the first half hour, and then 10 mg.kg-1.h-1 to maintain anaesthesia. Group C patients were given 10 mg.kg-1 thiopentone for induction and halothane for maintenance. The quality of anaesthesia was assessed by monitoring adverse effects, heart rate, blood pressure, the length of anaesthesia, the delay of the first spontaneous breath and eye opening, and extubation. Intraocular pressure was measured before and 3 min after intubation, and 5 min after extubation. The quality of anaesthetic induction and maintenance were very similar in both groups. Pain occurred more frequently at the injection site with propofol (p less than 0.01). Children in group P recovered more quickly, and extubation was possible much earlier in this group (p less than 0.05). However, restlessness was significantly more frequent in group P (n = 9) than in group C (n = 1) (p less than 0.01). Systolic, diastolic blood pressure and heart rate were significantly lower in group P (p less than 0.05; 0.001; 0.001 respectively). No significant decrease in intraocular pressure in both groups was observed. The use of propofol for eye surgery in children is acceptable, despite some restlessness during recovery.     

Sedation with propofol and fentanyl in patients under intensive care]

This study investigated the efficacy of a constant rate infusion of propofol and fentanyl in thirty patients requiring artificial ventilation for more than 24 h. A loading dose, which differed according to the patient's age, was administered over a 30 min period: 2.5 mg.kg-1 for patients less than 50 (G1) (n = 9), 2 mg.kg-1 for patients between 50 and 60 years old (G2) (n = 9), and 1.5 mg.kg-1 for patients over 60 (G3) (n = 12). This was followed by an infusion of 3 mg.kg-1.h-1 in G1 and G2, and 2 mg.kg-1.h-1 in G3. A 1 microgram.kg-1.h-1 infusion of fentanyl was also given. The degree of sedation was assessed with the Ramsay scale before starting, after induction, and every four hours thereafter. When this proved to be insufficient, the dose of propofol was increased by 0.5 mg.kg-1.h-1 as well as that of fentanyl by 0.5 microgram.kg-1.h-1. Heart rate, mean arterial blood pressure, blood propofol, creatinine, transaminase and lipid levels, and urine output were measured before, during, and after the infusion. The blood propofol level increased during the infusion, being correlated to the doses given (r = 0.64, p less than 0.001). Sedation lasted 91.7 +/- 57.7 h. After stopping the infusion of propofol, mean recovery times were 7.5 +/- 5.9 min (G1), 11.4 +/- 11.4 min, and 14.4 +/- 13.5 min (G3) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Recovery and discharge of patients after long propofol infusion vs isoflurane anaesthesia for ambulatory surgery

Fifty unpremedicated patients scheduled for outpatient restorative dentistry and/or oral surgery lasting 2 to 4 h were anaesthetized with either propofol infusion or isoflurane inhalation. Before induction of anaesthesia with propofol (2.5 mg.kg-1), all patients were given 75 mg of diclofenac and 0.01 mg.kg-1 vecuronium intravenously. Intubation was facilitated with suxamethonium (1.5 mg.kg-1) and anaesthesia was maintained in random order either with propofol infusion (12 mg.kg-1.h-1 for the first 20 min, 9 mg.kg-1.h-1 for the next 20 min, and 6 mg.kg-1.h-1 for the rest of the anaesthesia) or with isoflurane (inspired concentration 1-2.5%), both with nitrous oxide and oxygen (30%). The patients breathed spontaneously using a non-rebreathing circuit. Patients given propofol infusion became re-orientated faster (11.0 +/- 5.5 min vs. 16.5 +/- 7.5 min; P less than 0.01) and at 30 min walked along a straight line better (P less than 0.01). At 60 min, none of the propofol patients displayed an unsteady gait, whereas 11 of the 25 isoflurane patients did (P less than 0.001). None of the patients receiving propofol had emesis at the clinic, compared with 10 of the 25 patients receiving isoflurane (P less than 0.001). The overall incidence of emesis was 2 of 25 and 14 of 25 in the propofol and isoflurane groups, respectively (P less than 0.01). Patients receiving propofol were discharged home earlier than patients receiving isoflurane (80 +/- 14 min and 102 +/- 32 min, respectively; P less than 0.01). It is concluded that propofol allows early discharge of patients, even after long anaesthesias.     

Recovery after anesthesia with propofol in otorhinolaryngologic surgery of brief duration

This study was designed to assess recovery from total intravenous anaesthesia with propofol for short ENT procedures. Twenty-six patients (ASA I and II) were assigned to two groups of thirteen: one breathed air (Laser laryngeal microsurgery), the second N2O-O2 (FIO2 : 0.5) (various ENT procedures). The induction sequence was exactly the same for both groups: oral premedication with 10 mg diazepam one hour before surgery, I mg pancuronium bromide, 2 micrograms X kg-1 fentanyl, denitrogenation within 3 min, after which propofol was delivered (2.5 mg X kg-1). When the eye-lash reflex had disappeared (time recorded), 1.5 mg X kg-1 suxamethonium was given and laryngotracheal intubation carried out. A continuous infusion of propofol (9 mg X kg-1 X h-1) was started. Surgery began 5 +/- 2 min after the start of propofol infusion. The durations of anaesthesia, surgery and propofol infusion were similar in both groups. To have good surgical conditions, it was necessary to give repeated doses of propofol for 15 patients. Thus, the total dose of propofol was significatively different between the two groups: 24.5 +/- 6.7 mg X kg-1 X h-1 in group "air" versus 16 +/- 3.6 mg X kg-1 X h-1 in group "N2O-O2" (p less than 0.001). Extubation occurred within 16 +/- 8 min in group "air", being more rapid in group "N2O-O2" (11 +/- 9 min; no significant difference). Recovery was assessed with two psychomotor tests: choice reaction time (CRT) and tracing test (TT).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cerebrospinal fluid concentrations of propofol during anaesthesia in humans

The concentration of propofol in and surrounding the human brain during propofol anaesthesia is unknown. We measured simultaneously the concentration of propofol in cerebrospinal fluid (CSF) from an indwelling intraventricular catheter and the concentration in arterial blood in five neurosurgical patients before, during induction (at 2.5 and 5 min) and during a maintenance propofol infusion (at 15 and 30 min). After induction of anaesthesia with propofol 2 mg kg-1, anaesthesia was maintained with an infusion of 8 mg kg-1 h-1 for 15 min and then reduced to 6 mg kg-1 h-1. The plasma concentration of propofol increased rapidly during induction and reached a plateau concentration of mean 2.24 (SD 0.66) micrograms ml-1 after 5 min. The concentration of propofol in CSF showed a slower increase during induction and remained almost constant at 35.5 (19.6) ng ml-1 at 15-30 min after induction. The CSF concentration of propofol that we measured was 1.6% of the plasma concentration and consistent with the high protein binding of the drug in plasma.      

Comparison of propofol and methohexital for dental and maxillofacial surgery

A prospective study has been undertaken to compare a new intravenous anaesthetic agent, propofol, to methohexitone in 40 ASA I or II patients aged between 18 and 50 years undergoing maxillo-facial surgery and divided into two groups. Intramuscular premedication was standardized for all patients. In group I, propofol 2 mg X kg-1 was injected over 1 min in a peripheral venous line with fentanyl 0.86 microgram X kg-1, followed by an infusion of propofol 5 mg X kg-1 X h-1 and fentanyl 3 micrograms X kg-1 X h-1. In group II, the fentanyl dosage was the same as in group I, whilst methohexitone 3 mg X kg-1 was given for induction and 4.5 mg X kg-1 X h-1 for maintenance of anaesthesia. The following were recorded during induction, maintenance and recovery; haemodynamic parameters using a non invasive method; respiratory parameters; quality of anaesthesia; side-effects. Statistical analysis was performed using the Student t test and qualitative analysis using the Schwartz comparison test at 2%. The following results were found: the quality of anaesthesia with propofol was superior to that of methohexitone during the three stages of anaesthesia. The duration of induction was similar in both groups, but the quality of induction (occurrence of more minor side-effects; p less than 0.05) and intubation was in favour of propofol (p less than 0.05). During maintenance, stability of anaesthesia and a lesser incidence of side-effects were again in favour of the propofol group, in which a slower rate was also found (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of propofol and propanidid administered at a constant rate

So as to compare the anaesthesia obtained using propofol with that obtained using propanidid, 40 ASA I patients, aged between 18 and 50 years, who were to undergo elective orthopaedic or plastic surgery lasting more than 60 min, were randomly divided into two equal groups, one receiving propofol (PF) and the other propanidid (PD). All the patients received 0.5 mg atropine, 100 mg pethidine and 7.5 mg droperidol (10 mg if weight greater than 60 kg) intramuscularly 45 min before induction. Patients in group PF were then given 2 mg.kg-1 propofol over 1 min and 0.9 microgram.kg-1 fentanyl over 3 min, followed by a constant rate infusion of 5 mg.kg-1.h-1 propofol and 3 micrograms.kg-1.h-1 fentanyl. For PD patients, the doses of fentanyl were identical; they were given 10.6 mg.kg-1 propanidid over 3 min for induction, and 37 mg.kg-1.h-1 for maintenance. All the patients were intubated and ventilated mechanically. The usual anaesthetic parameters were monitored at induction, during surgery, and during recovery. Consciousness was lost more quickly with propofol (p less than 0.05), but the corneal reflex returned more rapidly in group PD (p less than 0.02). The time required for a full return to normal consciousness was identical in both groups. The fall, during induction, and the increase, during recovery, of Pasys were greater in group PD (p less than 0.05 and less than 0.001 respectively). Padia and heart rate were lower in group PF after the 30th min (p less than 0.05 and less than 0.01 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Propofol versus etomidate in short-time urologic surgery]

Thirty patients, scheduled for short urological surgical procedures and ranked ASA 1 or 2, were randomly assigned to two homogenous groups. In group P, they were given a 2 mg.kg-1 bolus of propofol and 10 micrograms.kg-1 of alfentanil, followed by a continuous infusion of propofol (5 mg.kg-1.h-1) and 5 micrograms.kg-1 doses of alfentanil. In group E, they were given a 0.3 mg.kg-1 bolus of etomidate, followed by an infusion (1.5 mg.kg-1.h-1). The doses of alfentanil were the same as in group P. Further doses of either propofol (0.5 mg.kg-1) or etomidate (0.2 mg.kg-1) were used should anaesthesia prove not to be deep enough. The patients were not intubated, and breathed spontaneously. Surgery lasted a mean of 18.3 +/- 11.8 min (group P) and 18.8 +/- 9.4 min (group E). The following parameters were studied: the amount of each agent required for maintenance of anaesthesia, the duration of apnoea at induction, the quality of anaesthesia and of muscle relaxation, adverse effects (coughing, trismus, restlessness, nausea, vomiting), the time required for recovery, and its quality. In group P, there was a 27% decrease in arterial pressure, without any tachycardia or hypoxia, together with a quick recovery of excellent quality. On the other hand, in group E, there was little or no haemodynamic alteration, but there often was a trismus at induction. Hypoxia also occurred during induction with etomidate, being severe enough in one case to require tracheal intubation and artificial ventilation. The reasons for this hypoxia seemed to be the apnoea and the trismus, which tends to hinder assisted ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of propofol and isoflurane on the neuromuscular block induced by atracurium]

Speed of onset, duration of action and recovery time for a bolus injection of atracurium were measured in two groups of patients. In group I anaesthesia considered of propofol, fentanyl, nitrous oxide and oxygen mixture. The induction dose of propofol was 2 mg/kg-1 followed by an infusion of 9.0 mg/kg-1/h-1 for first half hour and 4.5 mg/Kg-1/h-1 subsequently. In group II anaesthesia consisted of isoflurane, fentanyl, nitrous oxide and oxygen mixture. Isoflurane was given upon clinical needs. Speed of onset, duration of action, and recovery time for atracurium were measured in the two groups. No statistically significant differences between speed of onset and duration of action between the two groups were found. The recovery period from T1 = 10% to T1 = 70% twitch response was considerably longer with isoflurane (25 min +/- 6) than with propofol (18 min +/- 3) (p less than 0.01). Results obtained suggest that for adequate relaxation during tracheal intubation smaller doses of atracurium are not needed during isoflurane than propofol administration. Because of the longer recovery period of residual neuromuscular blockade during isoflurane anaesthesia decreasing doses of atracurium and careful monitoring of twitch depression tension are also suggested.     

Effects of propofol, propofol-nitrous oxide and midazolam on cortical somatosensory evoked potentials during sufentanil anaesthesia for major spinal surgery

Recording of cortical somatosensory evoked potentials (CSEP) enables monitoring of spinal cord function. We studied the effects of propofol, propofol-nitrous oxide or midazolam during sufentanil anaesthesia on CSEP monitoring during major spinal surgery. Thirty patients with normal preoperative CSEP were allocated randomly to one of the following anaesthesia regimens: propofol (2.5 mg kg-1 followed by 10-6 mg kg-1 h-1) with or without nitrous oxide, or midazolam (0.3 mg kg-1 followed by 0.15 mg kg-1 h-1) combined with sufentanil 0.5 microgram kg- 1 h-1 in the propofol and midazolam groups, or 0.25 microgram kg-1 h-1 in the propofol-nitrous oxide group. CSEP were elicited by alternate right and left tibial posterior nerve stimulation and recorded before and after induction (15 min, 1, 2 and 3 h), and during skin closure. CSEP latencies were not significantly modified in the three groups. CSEP amplitude decreased significantly in the propofol-nitrous oxide group (from mean 2.0 (SEM 0.3) to 0.6 (0.1) microV; P < 0.05) but not in the propofol (from 1.8 (0.6) to 2.2 (0.3) microV) or midazolam (1.7 (0.5) to 1.6 (0.5) microV) groups. The time to the first postoperative voluntary motor response (recovery) delay was significantly greater in the midazolam group (115 (19) min) compared with the propofol and propofol-nitrous oxide groups (43 (8) and 41 (3) min, respectively). Consequently, the use of propofol without nitrous oxide can be recommended during spinal surgery when CSEP monitoring is required.      

Haemodynamic effects of induction of general anaesthesia with propofol during epidural anaesthesia

PURPOSE: To clarify whether propofol administration during thoracic or lumbar epidural anaesthesia intensifies the haemodynamic depression associated with epidural anaesthesia. METHODS: Patients (n = 45) undergoing procedures of similar magnitude were randomly divided into three study groups: a control group (n = 15) receiving general anaesthesia alone and two study groups undergoing thoracic (n = 15) and lumbar epidural anaesthesia (n = 15) before induction of general anaesthesia. All patients received 2 mg.kg-1 propofol at a rate of 200 mg.min-1, followed by a continuous infusion of 4 mg.kg-1.hr-1. Mean arterial blood pressure (MAP) and heart rate (HR) were measured at baseline, three minutes after induction, and one minute after tracheal intubation in all three groups and at 20 min after epidural anaesthesia was established in the thoracic and lumbar groups. RESULTS: Following epidural anaesthesia, MAP decreased from 94 +/- 14 (SD) at baseline to 75 +/- 11 mmHg (P < 0.0001) in the thoracic group and from 92 +/- 12 to 83 +/- 15 mmHg in the lumbar group. After propofol administration, MAP decreased further in the thoracic group to 63 +/- 9 mmHg (P = 0.0077) and to 67 +/- 10 mmHg (P = 0.0076) in the lumbar group. The MAP following propofol induction in the thoracic group (P < 0.0001) and in the lumbar group (P = 0.0001) was lower than MAP in the control group (81 +/- 9 mmHg). HR decreased only in response to thoracic epidural anaesthesia (P = 0.0066). CONCLUSION: The hypotensive effects of propofol are additive to those of epidural anaesthesia, resulting in a profound decrease in mean arterial pressure.     

Comparison of midazolam and propofol in combination with alfentanil for total intravenous anesthesia

Hemodynamic function during induction of anesthesia, the alfentanil and naloxone requirements, and the speed of recovery from total intravenous anesthesia with alfentanil/midazolam (group M, n = 10) or alfentanil/propofol (group P, n = 10) were compared in patients undergoing lower limb surgery. Twenty patients were randomly assigned to receive either 2 mg/kg propofol in 5 min followed by 9 mg.kg-1.h-1 for 30 min and 4.5 mg.kg-1.h-1 until skin closure, or 0.42 mg/kg midazolam in 5 min followed by 0.125 mg.kg-1.h-1 until skin closure. Simultaneously, a variable-rate infusion of alfentanil was given. Patients were ventilated with 30% oxygen in air. In both groups blood pressure and heart rate decreased significantly (P less than 0.02) and to a similar extent during induction. The total dose of alfentanil was similar in both groups. No patient in group P and nine patients in group M needed naloxone (average dose 130 +/- 70 micrograms, P less than 0.001). Recovery, as judged by psychomotor tests (90% score was reached at 1 h in the P group and at about 4 h in the M group, P less than 0.001), sedative scores, and orientation in time and place, was shorter in group P than in group M. The conclusion is reached that propofol is superior to midazolam in total intravenous anesthesia with alfentanil.     

Continuous propofol infusion versus enflurane in children operated on for strabismus. Comparison of the quality of anesthesia and recovery conditions

In children, the use of a continuous infusion of propofol has not yet been reported. A study was therefore designed to compare the characteristics of anaesthesia and recovery when either propofol or enflurance was used as the main anaesthetic agent. All 42 children (14 girls, 28 boys), ASA I and scheduled for corrective squint surgery under general anaesthesia, received 350 micrograms.kg-1 midazolam and 40 micrograms.kg-1 atropine intrarectally 20 min before induction, which was carried out with 3 mg.kg-1 propofol intravenously in 20 s. The patients were then randomly assigned to two groups, according to the drug used for maintenance: group P (n = 21) received a continuous intravenous infusion of propofol, 18 mg.kg-1.h-1 for the first 30 min and 15 mg.kg-1.h-1 thereafter; group E (n = 21) received 2.5%, then, after 30 min, 2% enflurane. Both groups were given 15 micrograms.kg-1 dextromoramide and 0.09 mg.kg-1 vecuronium. During anaesthesia, the following parameters were monitored: systolic (Pasys), diastolic (Padia) and mean arterial (Pa) pressures, heart rate (fc), the presence or not of an oculocardiac reflex with or without a 20% fall in fc which responded to 10-15 micrograms.kg-1 atropine, the appearance of a cardiac dysrhythmia, duration of anaesthesia and the delay before extubation. Recovery was assessed 1, 2, 4 and 6 h postoperatively by using both clinical and psychomotor criteria, the latter being adapted to children having one or both eyes occluded.(ABSTRACT TRUNCATED AT 250 WORDS)     

Propofol anaesthesia and metabolic acidosis in children

BACKGROUND: We aimed to investigate the effect of propofol infusion anaesthesia on acid-base status and liver and myocardial enzyme levels of children during short-term anaesthesia. METHODS: Thirty-six children, aged 3-12 years, were randomized into two groups. In group P (n = 18), induction and maintenance were performed with propofol, 3 mg x kg-1 and 20, 15 and 10 mg x kg-1 x h-1, respectively. In group H (n = 18) following induction with 5 mg x kg-1 thiopenthal, anaesthesia was maintained with 2-3% halothane. Blood samples were obtained following anaesthesia induction and 30, 60 and 120 min after discontinuation of anaesthesia. RESULTS: There was no difference in lactate dehydrogenase, myocardial creatininephosphokinase, aspartate aminotransferase, alanine aminotransferase and cholesterol levels between and within the groups. All postoperative triglyceride levels were higher and pH levels were lower in group P than group H (P < 0.05) and there was no difference within the groups. CONCLUSIONS: In these healthy patients, short-term use of propofol did not result in significant acidaemia, nor alterations in hepatic or myocardial enzyme levels.     

Comparative effects of thiopentone and propofol on respiratory resistance after tracheal intubation

To compare the effects of propofol and thiopentone on tracheal intubation-induced bronchoconstriction, 37 patients were allocated randomly to anaesthesia with either thiopentone 4 mg kg-1 followed by a 15-mg kg-1 h-1 continuous infusion or propofol 3 mg kg-1 followed by a 9-mg kg-1 h-1 continuous infusion. Intubation was facilitated by vecuronium 0.1-0.2 mg kg-1. Respiratory system resistance (Rrs) was measured by a CP-100 pulmonary function monitor, 5 min after intubation. The 5-min post-intubation Rrs values were significantly lower in the propofol group (8.5 (SD 1.5) cm H2O litre-1 S-1) than in the thiopentone group (10.9 (3.2) cm H2O litre-1 S-1). Thirty minutes after commencing isoflurane-nitrous oxide anaesthesia, Rrs declined by 17.5 (SEM 3.6)% from baseline in the thiopentone group, but by only 1.6 (2.6)% in the propofol group. We conclude that the dose of propofol administered provided more protection against tracheal intubation- induced bronchoconstriction than an induction dose of thiopentone.      

Desflurane maintains intraocular pressure at an equivalent level to isoflurane and propofol during unstressed non-ophthalmic surgery

We have investigated the effects of desflurane compared with isoflurane and propofol on intraocular pressure (IOP) in 48 ASA I-II patients undergoing elective non-ophthalmic surgery. Anaesthesia was induced with thiopental 3-5 mg kg-1, fentanyl 2-4 micrograms kg-1 and vecuronium 0.1 mg kg-1. Patients were allocated randomly to receive propofol (n = 16) 4-8 mg kg-1 h-1, isoflurane (n = 16) or desflurane (n = 16) for maintenance of anaesthesia. Fentanyl was added if necessary. The lungs were ventilated with 70% nitrous oxide in oxygen. Arterial pressure, electrocardiography, heart rate and end-tidal carbon dioxide were measured throughout anaesthesia. IOP was measured before surgery, during maintenance and after emergence from anaesthesia with applanation tonometry by an ophthalmologist blinded to the anaesthetic technique. There was a significant decrease in IOP after induction of anaesthesia which did not differ between groups. Desflurane maintained IOP at an equivalent level to isoflurane and propofol.      

Propofol auto-co-induction as an alternative to midazolam co-induction for ambulatory surgery

We propose the use of an intravenous propofol/propofol auto-co-induction technique as an alternative to propofol/midazolam for induction of anaesthesia. We have studied 54 unpremedicated ASA 1 or 2 patients undergoing day-stay anaesthesia for minor orthopaedic surgery. All received 10 micrograms.kg-1 or alfentanil before induction, followed by either midazolam 0.05 mg.kg-1, propofol 0.4 mg.kg-1 or saline, and 2 min later, a propofol infusion at a rate of 50 mg.kg-1.h-1 until loss of eyelash reflex. We compared pre- and postinduction haemodynamic changes, complications at insertion of a laryngeal mask airway and recovery from anaesthesia in the three groups. Both co-induction techniques showed less postinduction hypotension and significant reduction of the total induction dose of propofol when compared to the control group. In the propofol/propofol group there was a decreased incidence of apnoea during induction of anaesthesia. These patients were discharged from hospital 2 h after the end of anaesthesia whereas patients in the midazolam/propofol group were discharged after 2 1/2 h (p < 0.001).     

Electroencephalographic arousal response during tracheal intubation and laryngeal mask airway insertion after induction of anaesthesia with propofol

Laryngoscopy and tracheal intubation, or insertion of a laryngeal mask airway may lead to an arousal response on the electroencephalogram. We studied whether more intense stimulation (laryngoscopy and tracheal intubation) causes a greater arousal response than less intense stimulation (laryngeal mask airway insertion). Thirty-four patients (ASA I-II) were anaesthetised with propofol 3 mg.kg-1, followed by vecuronium 0.15 mg.kg-1 and a propofol infusion of 10 mg.kg-1.h-1. Three minutes after induction of anaesthesia, either laryngoscopy and tracheal intubation (n = 18), or laryngeal mask airway insertion (n = 16) was performed. Laryngoscopy and tracheal intubation caused a significantly greater increase in blood pressure (but not heart rate) than laryngeal mask airway insertion (p < 0.05). Electroencephalogram responses were not different. More intense stimulation does not cause a greater arousal response during propofol anaesthesia.     

Measurement of respiratory effects of propofol by indirect spirometry

The effects of a continuous steady rate infusion of propofol on spontaneous ventilation were studied in eight unpremedicated ASA 1 male patients. All were non smokers, aged 29 +/- 8 years, and weighed 67 +/- 9 kg. After an initial 1 mg.kg-1 bolus, they received 10 mg.kg-1.h-1 propofol for 10 min, followed by 8 mg.kg-1.h-1 for a further 10 min, and then 6 mg.kg-1.h-1 during the whole study period. Endotracheal intubation was carried out using lidocaine for local anaesthesia. Spontaneous ventilation was assessed during three periods of five minutes: in the awake subject, using indirect spirometry (measurement of variations in chest circumference) and direct spirometry separately, and then, in the anaesthetized subject, using both methods simultaneously. This study aimed: a) to compare the results obtained with the two methods, b) to characterize the effects of propofol anaesthesia on chest wall mechanics using the partitioning of ventilation between rib cage and abdomen provided by the non-invasive method, and c) to assess abdominal compliance by means of a gastric balloon catheter. There was an increase in rib cage ventilation in the awake state, induced by the apparatus for direct spirometry (mouth piece, nose clip). This explained that the ventilatory depression induced by propofol anaesthesia was more pronounced when measured by the direct method. The major determinant of this depression was a shortened inspiratory time, and, to a lesser extent, a decreased mean inspiratory flow rate. By contrast to inhalational anaesthesia, rib cage ventilation was preserved during propofol anaesthesia. The decrease in abdominal ventilation was partly related to a lowered abdominal compliance, suggesting recruitment of the abdominal muscles.