Summary

The use of muscle relaxants, considered until recently as common practice in current neurosurgical anaesthesia protocols, becomes increasingly more questionable today. The reasons rely on the evolution of neurosurgery including the advent of new surgical techniques, the evolution of anaesthesia having the benefit of new drugs and devices, and the rationale for using muscle relaxants balanced against their potential side-effects and possible pharmacodynamic alterations in neurosurgical patients.

Summary

Background and objective: Administration of calcium safely and effectively reverses many of the electrophysiological actions of hyperkalaemia, but it has not been studied for pretreatment. Based on cellular studies, magnesium also has been suggested to prevent the effects of potassium on the heart. As their mechanisms of action differ, a combination of these drugs might have a synergistic protective action. Both compounds are inexpensive and can be administered safely in modest doses. We investigated whether magnesium, calcium or their combination could protect against hyperkalaemic cardiac arrest.

Methods: Twenty-four adult rats were anaesthetized with halothane and randomly pretreated with CaCl2 15 mg kg−1, MgSO4 30 mg kg−1, CaCl2 7.5 mg kg−1 + MgSO4 15 mg kg−1 or physiological saline. Potassium (0.01 mmol kg−1 h−1) was infused. The times to the first dysrhythmia, mean arterial pressure decrease to <40% of baseline and cardiovascular collapse were measured.

Results: Serum potassium concentrations increased to similar values in all groups (to 12.0 ± 0.2 mmol L−1 at the time of collapse). No differences in survival times were observed between groups. There was a trend for respiratory values to be better in the group receiving magnesium.

Conclusions: Pretreatment with magnesium, calcium or a combination of both did not influence the time to cardiovascular collapse, and is therefore – at least in our model – not of any benefit in preventing hyperkalaemic cardiac arrest.

Summary

Background and objective: Since reports have shown that outpatient preoperative evaluation increases the quality of care and cost-effectiveness, an increasing number of patients are being evaluated purely on an outpatient basis. To improve cost-effectiveness, it would be appealing if those patients who are healthy and ready for surgery without additional testing could be easily distinguished from those who require more extensive evaluation. This paper examines whether published studies provide sufficient data to determine how detailed preoperative history taking and physical examination need to be in order to assess the health of surgical patients and to meet the objective of easy and early distinction.

Methods: A MEDLINE search was conducted from 1991 to 2000 with respect to preoperative patient history and physical examination. Altogether, 213 articles were found, of which 29 were selected. Additionally, 38 cross-references, 7 articles on additional testing and 4 recently published papers were used.

Results: It is questionable to what extent an extensive history is relevant for anaesthesia and long-term prognosis. With respect to physical examination, it seems unreasonable to diagnose valvular heart disease based on cardiac auscultation only, and it is unclear which method should be used to predict the difficulty of endotracheal intubation. The benefits of routine testing for all surgical patients before operation are extremely limited and are not advocated.

Conclusions: The amount of detail of preoperative patient history and the value of physical examination to obtain a reasonable estimate of perioperative risk remains unclear. Although not evidence based, a thorough history taking and physical examination of all patients before surgery seems important until more evidence-based guidelines become available. Diagnostic and prognostic prediction studies may provide this necessary evidence.

Summary

Background and objective: In recent years, a large number of airway devices have been introduced into clinical practice as adjuncts to the management of the difficult airway. The purpose of this study was to evaluate the practices of Israeli anaesthetists in specific clinical situations and their familiarity with the use of a variety of airway devices and techniques.

Methods: A survey developed in our institution was sent to 300 attending anaesthetists representing all board-certified anaesthetists practising in Israel.

Results: Of the 153 respondents, 75% belonged to university hospitals. Ninety-six percent were skilled with laryngeal mask airways and 73% with fibreoptics. Seventy percent preferred regional anaesthesia with anticipated difficult intubation, continuation of anaesthesia with a laryngeal mask with failed intubation and a laryngeal mask for impossible mask ventilation. For the airway scenarios, awake fibreoptic, awake direct laryngoscopy, intubation under inhalation anaesthesia and tracheostomy were shared equally.

Conclusions: There is a high degree of adherence by Israeli anaesthetists to the American Society of Anesthesiologists' difficult airway algorithm. Current airway management practice patterns in Israel are presented.

Summary

Background and objective: The bispectral index of the electroencephalogram is a measure of the hypnotic component of anaesthesia and can be used to guide the administration of anaesthesia. This study compares bispectral index-guided anaesthesia with remifentanil and either propofol or isoflurane.

Methods: Eighty consenting patients were randomly assigned to two groups. Following induction with propofol and remifentanil, anaesthesia was maintained with remifentanil/propofol or remifentanil/isoflurane. Remifentanil infusion rates were guided by haemodynamic responses – maintaining mean arterial pressure and heart rate within 20% of baseline. Propofol and isoflurane administration was guided using the bispectral index (45–60). Thirty minutes before the end of surgery, morphine was administered (0.15 mg kg−1 intravenously). Fifteen minutes before end of surgery, propofol and isoflurane were reduced (bispectral index 60–75). At the end of surgery, the anaesthetic agents were discontinued. Groups were compared for recovery, remifentanil doses and signs of inadequate anaesthesia using the χ2-test and ANOVA (P < 0.05).

Results: The duration of surgery was longer in the propofol/remifentanil group (121 ± 53 versus 94 ± 40 min). Recovery data were not different between groups. The remifentanil infusion rate was significantly lower with additional isoflurane (0.18 ± 0.06 μg kg−1 min−1) than with additional propofol (0.31 ± 0.20 μg kg−1 min−1). The propofol infusion rate was 123 ± 48 μg kg−1 min−1; isoflurane concentration was 0.66 ± 0.13%.

Conclusions: Bispectral index-guided anaesthesia with remifentanil plus propofol or isoflurane results in the absence of postoperative recall and a fast recovery with both drug combinations. In our patients, at comparable bispectral index-levels, haemodynamic control requires higher doses of remifentanil with propofol than with isoflurane.

Summary

Background and objective: Subarachnoid block is a widely used technique for Caesarean section. Its quality can be improved by adding opioids to the local anaesthetics. We studied the quality of the block and its maternal–fetal repercussions when different doses of sufentanil were combined with hyperbaric bupivacaine using the intrathecal route in pregnant women undergoing Caesarean section.

Methods: This was a prospective, randomized, double-blind, controlled trial with 80 pregnant women, ASA I–II, who were scheduled for elective Caesarean section under subarachnoid block. Patients were distributed into four groups according to the dose of sufentanil used: no sufentanil (Group 1, control) or 2.5, or 5.0 or 7.5 μg sufentanil (Groups 2–4, respectively). In every group, the local anaesthetic used was hyperbaric bupivacaine 0.5% (12.5 mg) and the total volume of the solution 4 mL. The onset time of the block, maximum level of sensory block, motor block level, duration of analgesia, maternal side-effects and maternal–fetal cardiovascular repercussions were evaluated.

Results: Onset of the block was significantly shorter in the groups receiving opioids compared with the control group. Analgesia was significantly prolonged in Groups 3 and 4. The occurrence of pruritus and somnolence was significantly higher in the group receiving sufentanil 7.5 μg than in other groups. With the exception of pruritus, no differences were observed between groups with respect to cardiovascular or other maternal effects.

Conclusions: The addition of sufentanil 5.0 and 7.5 μg to hyperbaric bupivacaine provided adequate anaesthesia for Caesarean section and good postoperative analgesia. Pruritus was the most common side-effect and had a significantly higher incidence when a dose of sufentanil 7.5 μg was used.

Summary

Background and objective: To evaluate the efficacy, delay and duration of analgesia of three equianalgesic epidural doses of levobupivacaine, ropivacaine and bupivacaine during the first stage of labour.

Methods: One hundred and twenty-nine healthy primigravida in spontaneous labour who requested epidural analgesia were enrolled in a randomized observer-blinded study. Parturients were allocated to receive epidural levobupivacaine 0.0625%, ropivacaine 0.1% or bupivacaine 0.0625%. Sufentanil 10 μg was added to all solutions; the total volume of epidural solution was 20 mL. Pain was measured using a 100 mm visual analogue pain scale immediately before the epidural block, and at 5, 10, 15, 20 and 30 min thereafter. Motor block was evaluated using a modified Bromage scoring system. The adequacy of motor function for ambulation was also evaluated. Delay of analgesia was the time interval between the injection of the solution and the first painless contraction. Duration of analgesia was the time from the first painless contraction to the parturients' requests for further analgesia.

Results: Twelve parturients failed to complete the study. Eleven parturients had inadequate analgesia (four in Group Levobupivacaine, four in Group Ropivacaine and three in Group Bupivacaine; P > 0.05). Data was analysed from 34 parturients in Group Levobupivacaine, from 37 in Group Ropivacaine and from 35 in Group Bupivacaine. There were no differences in the delay of analgesia or in the number of parturients who were able to walk unaided. Levobupivacaine and ropivacaine produced more prolonged analgesia than bupivacaine (114 and 119 min, respectively, versus 89 min; P < 0.01).

Conclusions: During early labour, equipotent low concentrations of levobupivacaine, ropivacaine and bupivacaine, all with the addition of sufentanil 10 μg, produced similar pain relief and motor block, but levobupivacaine and ropivacaine produced a longer lasting analgesia. About 10% of parturients had inadequate analgesia with a single bolus of the tested solutions.

Summary

Background and objective: This prospective, randomized study was conducted to compare unilateral spinal block using small doses of hyperbaric bupivacaine and single-agent anaesthesia with sevoflurane in elderly patients undergoing hip surgery.

Methods: Thirty patients (>65 yr) undergoing hip fracture repair were randomly allocated to receive unilateral spinal anaesthesia with hyperbaric bupivacaine 7.5 mg 0.5% (Group Spinal, n = 15) or volatile induction and maintenance anaesthesia with sevoflurane (Group SEVO, n = 15). General anaesthesia was induced by increasing the inspired concentration to 5%. A laryngeal mask airway was placed without muscle relaxants, and the end-tidal concentrations of sevoflurane were adjusted to maintain cardiovascular stability. Hypotension (decrease in systolic arterial pressure >20% from baseline), hypertension or bradycardia (heart rate < 50 beats min−1) requiring treatment, and the length of stay in the postanaesthesia care unit was recorded. Cognitive functions were evaluated the previous day, and 1 and 7 days after surgery with the Mini Mental State Examination test.

Results: Hypotension occurred in seven patients of Group Spinal (46%) and in 12 patients of Group SEVO (80%) (P = 0.05). Phenylephrine was required to control hypotension in three spinal patients (21%) and four SEVO patients (26%) (n.s.). SEVO patients had lower heart rates than spinal patients from 15 to 60 min after anaesthesia induction (P = 0.01). Bradycardia was observed in three SEVO patients (22%). Discharge from the postanaesthesia care unit required 15 (range 5–30) min in Group Spinal and 55 (15–80) min in Group SEVO (P = 0.0005). Eight patients in Group Spinal (53%) and nine patients in Group SEVO (60%) showed cognitive decline (Mini Mental State Examination test decreased ≥ 2 points from baseline) 24 h after surgery (n.s.). Seven days after surgery, confusion was still present in one patient of Group Spinal (6%) and in three patients of Group SEVO (20%) (n.s.).

Conclusions: In elderly patients undergoing hemiarthroplasty of the hip, induction and maintenance with sevoflurane provide a rapid emergence from anaesthesia without more depression of postoperative cognitive function compared with unilateral spinal anaesthesia. This technique represents an attractive option when patient refusal, lack of adequate co-operation or concomitant anticoagulant therapy contraindicate the use of spinal anaesthesia.

Summary

Background and objective: A variety of drugs and techniques have been introduced into ambulatory anaesthesia. The technique as well as the drugs used may hasten or delay home discharge. We compared recovery profiles and side-effects of spinal anaesthesia and total intravenous anaesthesia.

Methods: Forty unpremedicated ASA I–II patients (18–65 yr) undergoing varicocele repair were randomly divided into two groups. Spinal anaesthesia (26-G atraumatic needle) with hyperbaric bupivacaine 0.5% 5 mg and fentanyl 25 μg were given to patients in Group Spinal (n = 20). Patients in Group TIVA (n = 20) received total intravenous anaesthesia with propofol and remifentanil given by continuous infusion; a laryngeal mask was used to secure the airway. The duration of surgery, time to home readiness and side-effects were recorded.

Results: The two groups were comparable with respect to patients' characteristics and duration of surgery. The times to achieve ambulation were similar between groups (Spinal = 78.4 ± 40.9 min, TIVA = 75.9 ± 13.8 min). Urinary voiding was a requirement for discharge after spinal anaesthesia and the time for home readiness was longer in Group Spinal (158.0 ± 40.2 versus 94.9 ± 18.8 min) (P < 0.05). Two patients reported pruritus and one reported postdural puncture headache in Group Spinal, whereas two patients reported nausea in Group TIVA. Patients in Group TIVA had a greater need for analgesia postoperation (P < 0.05).

Conclusions: In healthy unpremedicated men undergoing minor urological operations, total intravenous anaesthesia with remifentanil and propofol provided as safe and effective anaesthesia as spinal block with the advantage of earlier home readiness.

Summary

Background and objective: Although percutaneous nephrolithotomy has many advantages over open surgery, some endocrine and haemodynamic responses have been reported. However, the effects of anaesthetic agents on these responses have not previously been reported. This study compared the effects of sevoflurane and total intravenous anaesthesia using propofol and alfentanil on the haemodynamic and hormonal changes during percutaneous nephrolithotomy.

Methods: Forty-two ASA I–II patients aged between 15 and 65 yr were studied. Sevoflurane in Group S (21 patients) or TIVA in Group TIVA (21) was used for the maintenance of anaesthesia. Haemodynamic variables and serum concentrations of sodium and potassium were measured before, during and after the procedure. Arterial blood-gas status, plasma renin, aldosterone and adrenocorticotrophic hormone concentrations were measured before and during the procedure.

Results: Mean heart rate was lower during percutaneous nephrolithotomy in Group TIVA compared with Group S (P < 0.01). The mean systolic and diastolic arterial pressures were not different in both groups at any stage of measurement (P < 0.05). Plasma renin, aldosterone and adrenocorticotrophic hormone concentrations were increased during percutaneous nephrolithotomy in both groups, but the increase was greater in Group S (P < 0.05).

Conclusions: In the sevoflurane group, the concentrations of renin, aldosterone and adrenocorticotrophic hormone were significantly higher after 15 min of irrigation compared with the total intravenous anaesthesia group. Although the clinical significance of this difference was not clear, these changes should be considered in certain patient groups.

Summary

Background and objective: To evaluate the effects of pneumoperitoneum and the reverse Trendelenburg position on respiratory mechanics and blood-gases in morbid obese patients with chronic obstructive pulmonary disease and hypertension.

Methods: Sixteen morbid obese patients with chronic obstructive pulmonary disease and hypertension were studied. Mean arterial pressure, heart rate, respiratory resistance, dynamic respiratory compliance and peak inspiratory pressures were measured at four time points: 5 min after induction of anaesthesia (T1), 5 min after insufflation of the peritoneum (T2), 5 min after adoption of a 20° reverse Trendelenburg position (T3), and 5 min after deflation of the peritoneum (T4). Arterial blood-gas status was measured at the same measuring points.

Results: Respiratory compliance was 40 ± 12, 28 ± 8, 32 ± 8 and 37 ± 11 mL cmH2O−1 in T1, T2, T3 and T4, respectively. The changes were significant at T2, T3 and T4. Airway resistance and peak inspiratory pressures showed comparable changes throughout the study with that of respiratory compliance. Haemodynamic measurements showed no clinically significant changes in this study.

Conclusions: In morbid obese patients with chronic obstructive pulmonary disease and hypertension, a 20° reverse Trendelenburg position improved respiratory mechanics and oxygenation without any apparent adverse effects on haemodynamics during laparoscopic gastric banding surgery.

Summary

Background and objective: Statins are prescribed for patients with hypercholesterolemia. Atorvastatin is metabolized by cytochrome P4503A4 and inhibits P4503A4 activity in vitro. Alfentanil is a potent opioid used in clinical anaesthetic practice and is also metabolized by P4503A4. This study tested the hypothesis that chronic atorvastatin administration inhibits the metabolism of alfentanil.

Methods: Sixteen patients undergoing elective surgery were studied as matched pairs. One member of each pair was maintained on standard doses of atorvastatin for at least 4 months. Each patient received an alfentanil bolus (80 μg kg−1) intravenously (i.v.), followed by an alfentanil infusion (0.67 μg kg−1 min−1) for 90 min. Serial plasma alfentanil concentrations were measured using gas chromatography-nitrogen phosphorous detection. Pharmacokinetic parameters were calculated using two-compartment linear modelling.

Results: One patient and the corresponding match were excluded from the analysis. The elimination half-life of alfentanil was similar in the control and atorvastatin groups (98.8 ± 12.4 versus 98.3 ± 11.3 min, respectively). The clearance (Cl), volume of distribution at steady-state (Vdss) and area under the curve (AUC) were similar in the two groups (Cl = 0.20 (±0.06) and 0.22 (±0.04) L min−1, Vdss = 0.38 (±0.07) and 0.39 (±0.07) L kg−1, AUC = 0.05 (±0.02) and 0.04 (±0.01) mg min mL−1).

Conclusions: Concurrent atorvastatin administration does not alter the pharmacokinetics of alfentanil in patients undergoing elective surgery.

Summary

Background and objective: To compare the antiemetic efficacy of ondansetron with two different hypnotic drugs (propofol 15 mg, midazolam 1 and 2 mg) for the treatment of established postoperative nausea and vomiting (PONV).

Methods: Four-hundred-and-fifty-three patients scheduled for elective gynaecological or abdominal surgery were enrolled. One-hundred-and-twenty patients (26%) experienced postoperative emesis, and when nausea scores reached 2 or greater on a five-point scale, they were randomized to receive intravenously: propofol 15 mg (1.5 mL) in Group P, midazolam 1 mg in Group M1, midazolam 2 mg in Group M2 and ondansetron 4 mg in Group O.

Results: Four patients (13.3%) in Group P, 13 patients (43.3%) in Group M1, five patients (16.6%) in Group M2 and one patient (3.3%) in Group O required a second dose of the study drug. After administration of the study drugs, nausea scores were significantly lower in all groups than before these drugs were given. No patient had a sedation score over 3 (the patients remained awake and/or responded to verbal contact). The sedative effects of midazolam and propofol lasted for a much shorter time than the antiemetic effects of these drugs.

Conclusions: Propofol and midazolam used in subhypnotic doses were as effective as ondansetron in treating PONV in patients undergoing abdominal or gynaecological surgery without untoward sedative or cardiovascular effects.