Bispectral index, predicted and measured drug levels of target-controlled infusions of remifentanil and propofol during laparoscopic cholecystectomy and emergence

BACKGROUND

Target-controlled infusions (TCI) have been launched as simple, accurate and reliable delivery systems of intravenous drugs. Bispectral index of EEG (BIS) seems promising in measuring hypnotic effect of anaesthetic drugs. The aims of this study were to evaluate the accuracy of TCI systems in patients undergoing laparoscopic cholecystectomy and to correlate measured drug levels to BIS values. Data were analysed for possible gender differences during emergence.

METHODS

After written informed consent, 20 patients were enrolled in an open study. Remifentanil was set at 7.5 ng/ml as target throughout the whole procedure, and propofol at 5 microg/ ml at induction and 3 microg/ml after intubation. Values in blood samples of remifentanil and propofol were correlated to the estimated values and to systolic blood pressure and BIS. BIS values and measured drug levels during emergence and emergence time were compared for the two sexes.

RESULTS

Measured drug values varied considerably from the set target with a prediction error of -22% for remifentanil and 49% for propofol. The anaesthesia level was regarded as quite deep with a mean BIS during stable surgery of 42 +/- 7, and at this level we found no correlation between measured values of either of the two drugs and BIS. The emergence time was significantly shorter for women (12.6 +/- 2.5 min) than for men (19.0 +/- 4.2 min) (P=0.001), with no significant differences in measured levels of propofol or remifentanil or BIS during the emergence period.

CONCLUSION

Present systems for TCI of remifentanil and propofol result in large intra- and interindividual variations in measured drug levels, and measured levels differ from target. There may be possible interaction between the two anaesthetics at a pharmacokinetic level. Within the level of anaesthesia studied here, BIS was not an indicator of the actual drug levels. Women woke up significantly faster than men.

Lack of pre-emptive analgesic effect of (R)-ketamine in laparoscopic cholecystectomy

AIM

This study evaluated the pre-emptive analgesic effect of intravenous (i.v.) (R)-ketamine in laparoscopic cholecystectomy. (R)-ketamine was used due to the lower incidence of side-effects.

METHODS

Sixty patients who underwent surgery under general anesthesia were randomly allocated to 3 groups and studied in a double-blind manner. Two i.v. injections were administered: one after induction of anesthesia, approximately 3 min before surgery, and one after surgery. The placebo group (PLA, n = 20) received saline in both injections. The preoperative group (PRE, n = 20) received (R)-ketamine 1 mg/kg and then saline. The postoperative group (POST, n = 20) received saline and then (R)-ketamine 1 mg/kg. Postoperatively, the patients used a patient-controlled analgesia (PCA) pump. Pain was evaluated with a visual analog scale (VAS) at 30 min and every hour for 4 h and with a verbal rating scale (VRS) at 24 h and after 7 days.

RESULTS

There were no occurrence of side-effects from (R)-ketamine. VAS and VRS at 1, 2, 3, and 4 h postoperatively showed no statistical differences. In the POST group, extubation was delayed and pain score (VAS) at 30 min postoperatively was significantly lower (P < 0.05) than the two other groups. There were no statistical differences in meperidine consumption during the first 4 h postoperatively and no differences in consumption of analgesics at 24 h and 7 days.

CONCLUSION

In this study a 1 mg/kg dose of (R)-ketamine given at the end of surgery exerted a short-lasting hypnotic and analgesic effect. The same dose given preoperatively did not show postoperative analgesic effect or pre-emptive effect.

Recovery characteristics of sevoflurane- or propofol-based anaesthesia for day-care surgery

BACKGROUND

Sevoflurane has a low blood-gas partition coefficient resulting in a rapid recovery. Few studies have examined the maintenance and recovery characteristics of sevoflurane compared with propofol in a standardized outpatient population.

METHODS

The study was a multicentre study performed in 10 centres. One hundred and sixty-nine elective outpatients due for knee-arthroscopy received 100 mg diclofenac rectally as pain prophylaxis prior to induction of general anaesthesia with fentanyl 1.0-1.5 micrograms/kg + propofol 2.0-2.5 mg/kg i.v. Anaesthesia was maintained with 60% nitrous oxide in oxygen through a laryngeal mask and continuous administration of either: sevoflurane (group S) or propofol infusion (group P) in order to maintain stable haemodynamics. Data of postoperative function and side-effects were collected in a double-blind design, including a patient interview after 24 h.

RESULTS

The sevoflurane patients had a significantly faster emergence from anaesthesia, with response to commands at 6.9 +/- 0.4 min versus 8.2 +/- 0.4 min in the propofol group (P < 0.05, mean +/- SD). At 15 min after surgery, group S had a better score in the digit symbol substitution test and felt less confused in a visual analogue scale test compared with group P (P < 0.05). Peroperative bradycardia, nausea and vomiting and late postoperative dizziness were more common in group S. In the sevoflurane group, 32% had nausea or vomiting in the 24 h observation period compared with 18% for propofol (P < 0.05). There was no difference between group S and group P in postoperative pain, eligibility for recovery room discharge (75 +/- 12 versus 70 +/- 11 min) or home-readiness (155 +/- 12 versus 143 +/- 11 min).

CONCLUSION

Maintenance of anaesthesia with sevoflurane results in a more rapid emergence, but a higher incidence of nausea and vomiting compared with propofol. The side-effects were minor in our study, and did not result in any difference in time to discharge from the recovery ward or the hospital.

Outpatient laparoscopic cholecystectomy

INTRODUCTION

The results of laparoscopic cholecystectomy performed as an outpatient procedure were evaluated in a prospective study.

METHODS

Initially, only well motivated and healthy patients were offered outpatient laparoscopic cholecystectomy. After 50 procedures, all patients referred to the hospital, except those with American Society of Anesthesiologists (ASA) grade IV and those living alone, were included. Some 200 procedures were studied.

RESULTS

Twelve patients (6 per cent) were admitted, and 188 (94 per cent) were discharged 4-8 h after operation. Fifteen patients (8 per cent) who had early discharge were readmitted, nine with complications; in six no complications were documented. The frequency of minor complications was 2 per cent and of major complications 5 per cent. Some 173 patients who had successful outpatient laparoscopic cholecystectomy completed a questionnaire: 164 (95 per cent) characterized their experience as excellent, five (3 per cent) as good, two (1 per cent) as intermediate and two (1 per cent) as unacceptable.

DISCUSSION

This high achievement of day-case treatment, even in patients with ASA grade III, is explained by a new anaesthetic regimen together with good surgical technique and close follow-up.

[Admissions and readmissions from a unit of ambulatory surgery. Experiences after 2 411 surgical interventions]

Postoperative admissions to hospital from a hospital-based day-surgery unit were analysed over a period of 19 months. A total of 2,411 patients were surveyed. The admission rate within 24 hours of the operation was 1.5% (35 patients). Surgery, anaesthesia, pain and social reasons accounted for 37, 29, 20 and 14% of the admissions respectively. One patient was re-operated on. 24 patients (1%) were hospitalized later than 24 hours but within 30 days after surgery (mean 7.5 days), and were called re-admissions. Surgery (75.6%), pain (12.6%) and anaesthetic reasons (8.4%) accounted for the re-admissions. 12 patients (50%) underwent surgery when re-admitted. The number of admissions (4.1%, p < 0.001) and re-admissions (2.2%; p < 0.005) was significantly higher among gasteroenterologic patients than among patients operated on within other specialties. The time taken for the operation and the time spent under anaesthesia were significantly longer (p < 0.001 in both cases) for patients submitted to hospitalisation, but neither admission nor readmission was associated with age, gender, or health prior to operation (ASA classification).

[Laparoscopic cholecystectomy as ambulatory surgery. Safety requirements, benefit potential and patient satisfaction]

Ambulatory laparoscopic cholecystectomy was attempted using a new anaesthetic regimen in 50 patients. 46 patients were discharged 3-5 hours after operation, four were admitted to and remained in hospital for 1-5 days, one for psychosocial reasons, one because of emesis and two because of extended surgery. 45 of 46 ambulatory patients were generally satisfied after having experienced ambulatory cholecystectomy. Postoperative pain and nausea were moderate. Only 24% needed parenteral opioids postoperatively, and only 30% needed anti-emetic treatment. One woman suffered unacceptable pain and discomfort during the first two days at home, and would not prefer to have ambulatory treatment (questionnaire). Four patients were readmitted. Two had a forgotten stone in the common bile duct and underwent ERCP to extract the stone, without further complications. The third had a clip occluding the common bile duct. She was reoperated on in order to remove the clip and insert a T-tube in the common bile duct. Finally one woman was readmitted because of abdominal pain and vomiting, of which we never found the cause. She recovered spontaneously. Even though serious complications associated with biliary surgery were unavoidable in this ambulatory series, we have documented that patients can be operated on safely in this way. Most patients were very content, and experienced much less postoperative discomfort than they had expected.

[Combination of low molecular weight heparin and non-steroidal anti-inflammatory agents]

Non-steroidal anti-inflammatory drugs (NSAIDs) play an important part in postoperative relief of pain. Non-steroidal anti-inflammatory drugs and paracetamol should act as non-opioid basis analgesics in the postoperative period, leading to reduced need of opioid analgesia. This is beneficial, since it may reduce possible dosage-dependent side-effects of opioids such as nausea, tiredness and respiratory depression. The inhibition of prostaglandin synthesis by non-steroidal anti-inflammatory drugs also affects haemostasis, and the combination of these drugs with prophylaxis against postoperative thrombosis with heparin is controversial. We refer to a case history which illustrates this controversy. We also discuss the effect of non-steroidal anti-inflammatory drugs on pain and inflammation. Possible side-effects of these drugs and their interaction with heparin are reviewed.

Spinal anaesthesia for outpatient surgery

In a prospective study of 51 young male outpatients given spinal anaesthesia through a 25-gauge needle, we found a 37.2% incidence of postdural puncture headache. In addition, 54.9% complained of backache after surgery. Occurrence of headache significantly prolonged the sick-leave from work. General anaesthesia would be preferred by 31.4% of patients for a similar procedure in the future. These patients had a higher incidence of postoperative backache and pain during lumbar puncture. It is concluded that spinal anaesthesia is not a satisfactory technique for outpatient procedures in young men.

Undiagnosed phaeochromocytoma in the perioperative period. Case reports

Phaeochromocytomas appear as frequently as one in 1000-2000 patients. Release of catecholamines may be triggered by events in the perioperative period. Patients whose phaeochromocytomas are diagnosed in this period, have a mortality of about 80%. Three patients with perioperative debut of symptoms of a phaeochromocytoma are presented. A possible drug-induced release of catecholamines from the tumour is suggested for two of the patients. The first symptoms of a phaeochromocytoma may be arrhythmias and shock, which favours the use of adrenergic blockade prior to elective removal of phaeochromocytomas. Therapeutic approaches to the treatment of catecholamine-induced heart failure may be potassium and magnesium supplements and possibly drugs reducing circulating angiotensin II activities. Caution is advised in the use of digitalis.