Summary

Background and objective: Inaccurate measurements of body temperature following cardiopulmonary bypass may be associated with serious complications. The purpose of this study was to determine whether axillary and tympanic temperature measurements correlate with the urinary bladder temperature in the early postcardiac surgery period. Methods: Forty-nine adult patients who underwent cardiac surgery under cardiopulmonary bypass at our institution were prospectively studied. Urinary bladder, right axillary, right tympanic and left tympanic temperature measurements were simultaneously recorded at 0, 6, 12 and 18 h following cardiopulmonary bypass. Patients had one to four sets of recordings and a total of 629 temperature measurements were recorded. The mean difference (bias) between the bladder and each of the other methods and limits of agreement were calculated using Bland and Altman method. Results: The mean core body temperature recorded from the bladder on admission to the intensive care unit was 36.4°C. After 6, 12 and 18 h the mean core body temperature was 37.4°C (range: 35.2–39.0), 37.5°C and 37.45°C, respectively. The mean differences (bias) between the bladder temperature and the other three methods were: left tympanic, 0.65°C (95% CI: −0.24 to 1.58); right tympanic, 0.57°C (95% CI: −0.48 to 1.63) and right axillary, 0.55°C (95% CI: −0.27 to 1.36). Conclusions: The axilla and tympanic membrane are unreliable sites for core body temperature measurement early after cardiopulmonary bypass in adult patients and clinical decisions should be based on more reliable methods.

Summary

Background and objectives: The sustained attention to response task (SART) test is a sensitive indicator of deficits in sustained attention and is simple to perform. Sustained attention is impaired for a short period after minor surgery under general anaesthesia but the magnitude and duration of this effect after major surgery is unknown. We used the SART test to investigate deficits in sustained attention in patients undergoing major surgery under general anaesthesia. Methods: The SART test was completed before surgery and at 24, 48 and 72 h postoperatively by 20 ASA I–II female patients (mean age 48.6 yr) undergoing total abdominal hysterectomy under general anaesthesia. It was also completed by 20 age-matched female controls at similar time intervals to evaluate the effect of repeated test performance. Results: There was a significant (P < 0.05) interaction between the groups in number of errors made (a measure of sustained attention deficit). The number of errors decreased in control subjects on repeated performance of the SART test but remained unchanged in patients undergoing total abdominal hysterectomy. The differences between groups remained significant after 72 h (P < 0.05). Patients' overall response times slowed significantly at 24–48 h (P < 0.05), but this recovered by 72 h after surgery. In contrast, overall response times in the control group tended to accelerate on repeated performance of the SART. Conclusions: The results of this study suggest that 72 h following major surgery patients have deficits in sustained attention compared with controls. Control subjects demonstrated a marked learning effect on repeated test performance compared with patients.

Summary

Background and objective: Percutaneous nephrolithotripsy (PCNL) is used for the fragmentation and removal of stones from the renal pelvis and renal calyceal systems. We compared the effects of propofol–alfentanil or propofol–remifentanil anaesthesia on haemodynamics, recovery characteristics and postoperative analgesic requirements during percutaneous nephrolithotripsy. Methods: Thirty non-premedicated patients were randomly allocated to receive either propofol–alfentanil (Group A) or propofol–remifentanil (Group R). The loading dose of the study drug was administered over 60 s (alfentanil 10 μg kg−1 or remifentanil 1 μg kg−1) followed by a continuous infusion (alfentanil 15 μg kg−1 h−1 or remifentanil 0.15 μg kg−1 min−1). Propofol was administered until loss of consciousness and maintained with a continuous infusion of 75 μg kg−1 min−1 in both groups. Atracurium was given for endotracheal intubation at a dose of 0.5 mg kg−1 and maintained with a continuous infusion of 0.4 mg kg−1 h−1. Mean arterial pressure heart rate, the total amount of propofol, time of recovery of spontaneous ventilation, extubation and eye opening in response to verbal stimulus and analgesic requirement were recorded. Results: In Group A, mean arterial pressure was higher at the first minute in the prone position, and during skin incision and lithotripsy, and heart rate was higher during skin incision and lithotripsy when compared with Group R (P < 0.05). The total amount of propofol did not differ between groups. Time of recovery of spontaneous ventilation, extubation and eye opening were significantly shorter in Group R than Group A (P < 0.05). Conclusions: Both propofol–remifentanil and propofol–alfentanil anaesthesia provided stable haemodynamics during percutaneous nephrolithotripsy, whereas propofol–remifentanil allowed earlier extubation.

Summary

Background and objective: We tested the hypothesis that disturbances of the visual pathway following sevoflurane general anaesthesia (a) exist and persist even after clinical discharge criteria have been met and (b) are associated with decreased contrast sensitivity.

Methods: We performed pattern and full-field flash electroretinograms (ERG) in 10 unpremedicated ASA I patients who underwent nitrous oxide/sevoflurane anaesthesia. ERG and contrast sensitivity were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which the Post Anaesthesia Discharge Score first exceeded 9 was also noted. Data were analysed using paired, one-tailed t-tests and Pearson's correlation coefficient.

Results: On the full-field photopic ERG, b-wave latency was greater at each postoperative time point (31.6 ± 1.1 and 30.8 ± 1.1 ms) compared to preoperatively (30.1 ± 1.1 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential latencies were greater on discharge from the recovery room compared with pre-anaesthetic values (23.1 ± 3.1 vs. 22.4 ± 3.3 ms, P = 0.01) and returned to baseline by 2 h after emergence from anaesthesia. Also at 2 h after emergence from anaesthesia: (a) P50 latency on the pattern ERG was greater than at baseline (81.5 ± 17.9 vs. 51.15 ± 22.6 ms, P = 0.004); (b) N95 amplitude was less compared to pre-anaesthetic values (2.6 ± 0.5 vs. 3.3 ± 0.4 μV, P = 0.003) and (c) contrast sensitivity was less compared to baseline values (349 ± 153 vs. 404 ± 140, P = 0.048). A positive correlation was demonstrated between contrast sensitivity and both N95 amplitude and b-wave latency (r = 0.99 and r = −0.55 at significance levels of P < 0.005 and P < 0.05, respectively).

Conclusions: Postoperative ERG abnormalities and associated decreases in contrast sensitivity are consistently present in patients who have undergone nitrous oxide/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.

Summary

Background and objective: We tested the hypothesis that disturbances of the visual pathway persist following general anaesthesia, even after normal clinical discharge criteria have been met.

Methods: We performed full-field flash electroretinography in the right eye of 10 unpremedicated ASA I patients who underwent N2O/sevoflurane anaesthesia. Electroretinograms were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which postanaesthesia discharge score first exceeded 9 was also noted. Data were analysed using paired, one-tailed Student's t-test.

Results: Latency of the b-wave on the photopic electroretinogram was greater at each postoperative time point (30.5 ± 0.9 and 30 ± 1.3 ms), compared to preoperative values (29.2 ± 0.8 ms, P < 0.001 and P = 0.04, respectively). The A–B amplitude of the b-wave was less postoperatively (220.3 ± 52.7 and 210.3 ± 42.7 μV) compared to values before operation (248.1 ± 57.6 μV, P = 0.03 and P = 0.01, respectively). Oscillatory potential latencies were greater at each postoperative time point (21.4 ± 0.5 and 20.8 ± 0.6 ms) compared to before operation (20.4 ± 0.4 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential amplitudes were less at the first postoperative time point (17.5 ± 6.1 μV), compared to preoperative values (22 ± 6.4 μV, P = 0.04).

Conclusions: Postoperative electroretinogram abnormalities are consistently present in patients who have undergone N2O/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.

Summary

Background and objective: The randomized, patient- and observer-blinded study was performed in 120 patients undergoing ear, nose and throat surgery to test the hypothesis that intravenous anaesthesia with propofol–remifentanil when compared with a balanced anaesthesia technique using isoflurane–alfentanil improves the speed of recovery, minimizes postoperative side-effects and, thus, leads to an improved quality of recovery without increasing total costs.

Methods: The total costs for each anaesthesia technique were calculated considering drug acquisition costs, personnel costs for the additional time spent in the operating room and the postanaesthesia care unit until fast-tracking eligibility, and the costs to treat the side-effects during and after operation.

Results: The times from the end of surgery to tracheal extubation and the time until leaving the operating room were not different between the two groups. However, more patients receiving intravenous anaesthesia (80 versus 49%) were eligible for fast tracking and thus could bypass the recovery room. This was associated with an average cost saving of €6.00 per patient. However, intravenous anaesthesia was associated with higher total costs (€89 versus €78) mainly because of higher acquisition costs of the anaesthetics (€34.60 versus €16.50). There was no difference in the quality of recovery as measured by a Quality of Recovery score and patient satisfaction between the two groups.

Conclusions: The higher acquisition costs of the intravenous anaesthetics propofol and remifentanil cannot be compensated for by improved speed of recovery. This anaesthesia technique is more cost intensive than balanced anaesthesia using isoflurane and alfentanil.

Background and objective: Cognitive dysfunction has been reported after general anaesthesia, but its assessment is time consuming and difficult to evaluate. This pilot study assessed the feasibility of using the Sustained Attention to Response Test to assess 35 ASA I-II adults (mean age 31.6 yr) undergoing day case surgery under general anaesthesia, and 25 ASA I-II adults (mean age 47.8 yr) undergoing day case surgery under local anaesthesia.

Methods: The Sustained Attention to Response Test was performed before surgery and repeated 2 h after surgery.

Results: When patients repeated the test after surgery under local anaesthesia, the number of incorrect responses increased, but reaction times decreased (P < 0.05). Following general anaesthesia, the number of incorrect responses increased (P < 0.05), but reaction times remained unchanged.

Conclusions: The Sustained Attention to Response Test is simple to administer and may be a useful tool when comparing different anaesthetic techniques and their effects on postoperative deficits in sustained attention.

Background and objective: In this randomized, double-blind study, we aimed to investigate the effect of aminophylline on recovery from sevoflurane.

Methods: One-hundred ASA I–II patients scheduled for elective surgery were randomly divided into two groups receiving either NaCl 0.9% (Group 1, n = 50) or aminophylline 5 mg kg−1 (Group 2, n = 50). All patients were premedicated with atropine 0.01 mg kg−1 and midazolam 0.06 mg kg−1 intramuscularly. Anaesthesia was induced with propofol 2 mg kg−1 for muscle relaxation, and atracurium 0.5 mg kg−1 was maintained with sevoflurane 2% in 50% oxygen and nitrous oxide. Further atracurium (0.1 mg kg−1 was given when needed. Aminophylline or saline was given after sevoflurane was discontinued. Heart rate, mean arterial pressure, peripheral oxygen saturation, the duration of anaesthesia and recovery times (eye opening, verbal response, extubation and successful performance of arithmetical calculations) were recorded.

Results: There were no statistically significant differences in mean arterial pressure, peripheral oxygen saturation and anaesthesia time between the two groups. Heart rate increased significantly (P < 0.05) after aminophylline and was also higher than in the placebo group. Recovery times were significantly shorter (P < 0.001) in the patients receiving aminophylline.

Conclusions: Aminophylline speeded recovery after sevoflurane anaesthesia and it may have some advantage in anaesthesia practice for patients.

Background and objective The use of tension-free tape in the vagina is a relatively new surgical procedure for the treatment of urinary incontinence. Traditionally, the procedure is carried out using local anaesthesia and sedation. We aimed to assess the quality of anaesthesia obtained during insertion of tension-free vaginal tape using local anaesthetic infiltration and intravenous conscious sedation.

Methods Twenty-four patients were studied using intravenous midazolam, fentanyl and infiltration with 0.5% prilocaine and epinephrine. Visual analogue scores before operation were used to assess anxiety. The digit symbol substitution test was used before and after surgery to assess psychomotor recovery, and amnesia for the procedure was assessed by means of picture recall. A nurse, anaesthetist and surgeon independently assessed quality of anaesthesia based on vocalization, facial expression, movement and co-operation with incontinence testing.

Results The nurse, anaesthetist and surgeon reported good or excellent conditions in 18, 14 and 22 cases, respectively. There was no significant psychomotor impairment using the digit symbol substitution test, with mean (standard deviation) preoperative and postoperative scores of 22 (8) and 21 (7) correctly matched symbol digit pairs. There was a significant correlation between preoperative anxiety and intraoperative fentanyl requirement (r=0.48, P < 0.05).

Conclusion Satisfactory anaesthetic conditions can be achieved for the insertion of tension-free vaginal tape using local anaesthesia with sedation.

Background and objective Variability in blink duration was examined to see whether it was sensitive to sevoflurane sedation at 0.05 and 0.1 minimum alveolar concentration (MAC).

Methods Blinks were measured with an infrared transducer in eight subjects. Sedation was scored using a visual analogue scale (VAS).

Results At baseline, 0.05 and 0.1 MAC sevoflurane, respectively, the overall median value of blink duration and its interquartile range were 95 (80–110) ms, 198 (163–245) ms and 210 (130–980) ms. The median percentage of blinks exceeding 500 ms was 0% (0–0.7%), 33.3% (25.5–34.7%) and 25% (15.7–63.3%) respectively. Values during 0.05 and 0.1 MAC sevoflurane were significantly different from baseline (P < 0.035) but not from each other. Baseline visual analogue scales showed large intersubject variability. Compared with baseline, VAS scores were higher at 0.05 MAC (P < 0.035) but not at 0.1 MAC. After discontinuing sevoflurane, median blink duration returned to baseline with a recovery half-life of 2.6 min (R2 = 0.95).

Conclusion Blink duration is a sensitive measure of sevoflurane sedation even at 0.05 MAC.

Background and aim We investigated the haemody-namic stability and emergence characteristics of isoflur-ane/nitrous oxide anaesthesia supplemented with remifentanil or fentanyl in patients undergoing carotid endarterectomy.

Methods Anaesthesia was induced with propofol (1–2mgkg−1) and either remifentanil (O.5μgkg−1) or fentanyl (1 μgkg−1), followed by an infusion of remifentanil (0.2 μg kg−1 min−1) or fentanyl (2 μg kg−1 h−1).

Results There were no significant differences between the groups in haemodynamic variables, postoperative pain, nausea or vomiting. After induction there was a significant decrease in mean arterial pressure for both groups (P<0.001) and a decrease in heart rate (P=0.001) in the remifentanil group. In both groups these haemodynamic changes continued during maintenance of anaesthesia (P<0.05). The time to eye opening after surgery was significantly shorter with remifentanil compared with fentanyl (6.62±3.89 vs. 18.0±15.18min, P=0.015).

Conclusion Remifentanil appears to be a comparable opioid to fentanyl when supplementing isoflurane/nitrous oxide anaesthesia for carotid endarterectomy.

Background and aim We evaluated the costs and benefits of total intravenous anaesthesia compared with a balanced anaesthesia regimen.

Methods One-hundred and twenty-four patients undergoing cataract surgery were randomized to either a pro-pofol/remifentanil or an isoflurane/fentanyl group. In the propofol/remifentanil group, both drugs were used for induction and maintenance of anaesthesia; in the isoflurane/fentanyl group, anaesthesia was induced with etomi-date and fentanyl and maintained with isoflurane and fentanyl. All patients received mivacurium for muscle relaxation and the lungs were ventilated mechanically. The use of propofol and remifentanil resulted in a faster emergence and an overall savings per case of € 12.25 due to a reduction in personnel costs which outweighs the higher drug acquisition costs.

Results In the propofol and remifentanil group, more patients were satisfied and would accept the same anaesthetic again.

Conclusion We conclude that propofol and remifentanil is more cost-effective than isoflurane/fentanyl due to its better recovery profile, reduced total direct costs and higher patient satisfaction.