The isoflurane-saving and CO2-retaining effects of a charcoal filter were compared with a Siemens standard heat and moisture (HME) exchanger and an emptied specimen (dummy). Isoflurane was delivered during the inspiratory phase and consumption investigated at 10, 15 and 25 cycles min−1. The investigation was performed by ventilation with humidified air with a constant end-tidal CO2 and temperature. For a comparison, isoflurane was delivered in a conventional manner via the ventilator. The arrangement with a charcoal filter reduced the isoflurane consumption by a factor of 2.0−2.6, depending on ventilatory rate. Most of the saving was a result of the method of isoflurane delivery (factor 1.4−2.0), while adding the reflector gave a further reduction (factor 1.3−1.5). One circumstance that reduced the net efficiency of the charcoal filter was that it also reflected CO2; consequently, total minute ventilation had to be increased to maintain constant end-tidal CO2.

The efficacy and side effects of 100 lumbar epidural treatments with low concentrations of bupivacaine (1 mg mL−1), fentanyl (2 μg mL−1) and adrenaline (2 μg mL−1) combined with rectal paracetamol were prospectively evaluated in children aged 4–14 years after femoral osteotomy. The mean treatment time was 43 h and the mean dose was 0.18 mL kg−1 h−1. Ninety-nine per cent of the children were either without pain or experienced very low pain at rest for at least 80% of the treatment time. The same was the case in 80% of children when pain evaluation was made on active movement. No cases of seizures, signs of catheter migration, hypotension or respiratory depression were observed. Sixty-three per cent of the patients experienced nausea or vomiting, but antiemetic treatment was indicated in only 11%. One epidural treatment had to be stopped in a child who did not respond to antiemetics. The incidence of pruritus was high (49%), but the symptoms were mild and limited.

The effects of controlled hypotension induced with trimethaphan (TMP), nitroglycerin (TNG) or prostaglandin E1 (PGE1) during sevoflurane anaesthesia on hepatic function were studied in 28 patients undergoing spinal fusion surgery. Patients were randomly divided into three groups to receive TMP (group A, n=10), TNG (group B, n=10) or PGE1 (group C, n=8). Anaesthesia was maintained with N2O and sevoflurane. The mean arterial blood pressure was maintained at 60 mmHg for 90 min. Measurements included arterial ketone body ratio (AKBR-acetoacetate/3-hydroxybutyrate), SGOT, SGPT, LDH, blood glucose and blood gases were made. Measurements were taken before hypotension, 60 min and 90 min after starting hypotension, 60 min after recovery from hypotension and on the post-operative day. AKBR showed no significant change. SGOT, SGPT and LDH were within normal limits. Controlled hypotension induced with TMP, TNG or PGE1 under sevoflurane anaesthesia in surgical patients did not cause hepatocellular damage.

Summary

Background and objective: The use of midazolam for conscious sedation is an accepted method of anxiety control in restorative dentistry. A lack of predictability in its effects requires the dose of midazolam to be adjusted to individual patient's requirements. We determined whether patient-controlled sedation was a suitable alternative to operator-controlled sedation in restorative dentistry.

Methods: A randomized crossover clinical trial involving 35 consecutive patients undergoing similar dental procedures. Patients were randomly given midazolam, administered either by the patient or by the operator at the first visit and the alternative option on the second visit. All patients were ASA I–II and their ages ranged between 20 and 48 yr. Blood pressure, heart rate, oxygen saturation and patient satisfaction were recorded.

Results: The onset time and initial dose for sedation were similar with the two methods of administration and the sedation scores and vital signs were satisfactory. In the patient-controlled group the mean total dose of midazolam was 7.9 (±4.2 SD) mg cf. 4.2 (±1.8 SD) mg in the operator-controlled group (P < 0.05). The time to fitness for discharge (15.4 (± 11.9 SD) min) was greater in the patient-controlled group cf. the operator-controlled group (8.5 (±9.5 SD) min), P < 0.05.

Conclusion: This study shows that patient-controlled sedation is a suitable alternative to operator-controlled sedation in the management of anxious dental patients.

Summary

Background and objective: The aim of this study was to assess postoperative patients' self-evaluation after xenon anaesthesia compared to total intravenous anaesthesia with propofol. Methods: 160 patients aged 18–60 yr, ASA I–II undergoing elective surgery took part in this randomised-controlled trial. After approval by the local Ethics Committee and as soon as the patients had given their written informed consent, they were randomly allocated to either the xenon (n = 80) or propofol (n = 80) group. In both groups remifentanil was used as opioid. The postoperative patients' self-evaluation was assessed with a double-blind telephone poll. Early spatial orientation, patients' self-evaluation of anaesthesia, choice of the same anaesthesia for future operations and recall of uncomfortable feelings after anaesthesia were determined. Results: 116 Patients were analysed, 63 in the xenon and 53 in the propofol group. The two study groups were comparable with respect to age, weight, height, gender and ASA classification. The two groups indicated similar values in the early spatial orientation at the onset of recovery and thereafter. Patients' self-evaluation of anaesthesia with main emphasis at high marks and repetition of the same anaesthesia if necessary were similar in both groups. Recalls of uncomfortable feelings were comparable but not for postoperative pain and appetite/thirst which appeared with a significantly higher incidence in the xenon group. Conclusions: Patients' self-evaluation and memory of early spatial orientation following xenon anaesthesia are comparable to propofol.

The bispectral index, a value derived from the electroencephalogram, has been proposed as a measure of anaesthetic effect. The aim of the present study was to evaluate the bispectral index during midazolam–fentanyl anaesthesia for cardiac surgery for its possible role as a predictor of increases in systolic blood pressure during endotracheal intubation and sternotomy. After institutional approval 15 consenting patients, scheduled for elective cardiac surgery, were selected for the study. Anaesthesia was induced in all patients with a loading dose of fentanyl 7.5–10 μg kg−1, midazolam 0.15 mg kg−1 and pancuronium 0.1 mg kg−1. After a further bolus dose of fentanyl 10–12.5 μg kg−1 prior to the start of incision and sternotomy, maintenance infusion rates of fentanyl 4–6 μg kg−1 h−1 and midazolam 0.1 mg kg−1 h−1 were started and continued through surgery at the discretion of the anaesthetist and guided by the presenting clinical and haemodynamic responses. The control of anaesthesia was never based on the value of the bispectral index. The mean bispectral index value decreased from 95.7 (3.1) at base-line to 59.5 (12.0) after induction of anaesthesia and then remained below 70 throughout surgery. However, there was an important interindividual variability in bispectral index values despite standardized dosages of fentanyl and midazolam. There was no significant correlation between the bispectral index values in the pre-intubation and pre-incision period and the changes in systolic blood pressure during endotracheal intubation and sternotomy, respectively. In conclusion, the large intersubject variability in the bispectral index values should be investigated further in the light of the great variability in the clinical effects of midazolam and fentanyl. The lack of significant correlation between the bispectral index values and the haemodynamic responses suggest that the bispectral index, which is a helpful monitor of anaesthetic depth, is not a very reliable monitor of global anaesthetic adequacy during total intravenous anaesthesia with a combination of midazolam and fentanyl in cardiac surgical patients.

Summary

Background and objective: Different anaesthetic techniques are used during breast surgery but are frequently associated with unsatisfactory postoperative analgesia. Paravertebral nerve blockade has recently been proposed as a favourable alternative for this type of surgical procedure, providing excellent pain relief and a reduced incidence of postoperative nausea and vomiting. The aim of the present study was to compare the use of a nerve-stimulator guided paravertebral nerve blockade technique to regular general anaesthesia for breast surgery.

Methods: Sixty patients were prospectively randomized to receive either paravertebral nerve blockade or general anaesthesia for breast surgery. The primary end-point of the study was to assess postoperative analgesia (visual analogue scale and supplemental opioid requirements); the incidence of postoperative nausea and vomiting and length of hospital stay were considered as secondary outcome measures.

Results: Visual analogue scores both at rest and at movement, as well as the need for supplemental opioid administration during the first 3 days postoperatively, were significantly lower in patients handled with paravertebral nerve blockade compared to patients receiving general anaesthesia (P < 0.05). The number of patients free from nausea and vomiting after operation was significantly higher in the paravertebral nerve blockade group (93%) compared to the general anaesthesia group (67%) (P < 0.05). The use of paravertebral nerve blockade was also associated with a significantly shorter hospital stay (median 1 day) compared to general anaesthesia (2 days) (P < 0.01). Both the performance of the block and the intraoperative conditions was well accepted by the vast majority of patients treated by paravertebral nerve blockade (97%).

Conclusion: The use of paravertebral nerve blockade was associated with improved postoperative pain relief, a reduced incidence of nausea and vomiting after operation and a shorter duration of hospital stay compared to general anaesthesia in patients undergoing breast surgery.

Summary

Background and objective: The aim of this study was to investigate the effect of ketamine on the endocrine and lipid metabolic status of the renal-banded animals. Methods: Forty male rats were randomly divided into four groups. Group A served as control, Group B animals received ketamine intraperitoneally at a dose of 100 mg kg−1, Group C was submitted to 2-kidney 1-clip experimental hypertension and Group D received ketamine as above, as well as being submitted to renal artery clipping. Atrial natriuretic peptide, angiotensin II and free fatty acid concentrations were measured in serum. In addition, adipose tissue lipoprotein lipase activity and angiotensin II content were determined, while the left ventricular weight relative to body weight was used as a cardiac hypertrophy index. Results: In renal-banded rats (Groups C and D) serum atrial natriuretic peptide, free fatty acid and angiotensin II concentrations as well as ventricular weight were increased, while adipose tissue lipoprotein lipase activity was lower than in control animals (Groups A and B). Ketamine administration did not influence angiotensin II concentrations either in normal (Group B) or banded rats (Group D). Ketamine increased serum atrial natriuretic peptide and free fatty acid concentrations only in normal animals (Group B). It had no influence on adipose tissue lipoprotein lipase activity either in normal (Group B) or banded animals (Group D). Adipose angiotensin II content did not differ between the four groups. Conclusion: Ketamine increased the atrial natriuretic peptide and free fatty acid concentration in normal rats. In 2-kidney 1-clip animals, ketamine did not elicit an additional response of serum atrial natriuretic peptide or free fatty acids levels. Its contribution to these factors was not significant.

The suitability of tramadol suppositories for inclusion in our hospital formulary for the treatment of mild to moderate post-operative pain was evaluated. In an open randomized trial, rectal tramadol was compared with our standard treatment acetaminophen/codeine suppositories. We expected tramadol to be equally effective as our current standard but with fewer side effects. Forty patients were treated with either tramadol suppositories 100 mg 6 hourly (qds) or acetaminophen/codeine suppositories 1000/20 mg qds.Patients were comparable with regard to demographic data and type of surgery and anaesthesia. Post-operative pain was scored with the aid of a Visual Analogue Scale before each drug administration, at rest and during movement. Side effects, notably nausea and vomiting, were recorded by interviewing the patients and by inspecting the nursing report. There was no difference in pain scores between the two groups. The incidence of nausea and vomiting was significantly higher in the tramadol-treated (84%) than in the acetaminophen/codeine treated group (31%). The relative risk of experiencing an episode of nausea under treatment with tramadol was 2.7 (95% confidence interval: 1.3–5.3; P=0.0001) as compared with acetaminophen/codeine. We conclude that for acute treatment of mild to moderate post-operative pain frequent nausea and vomiting makes tramadol suppositories less suitable than acetaminophen/codeine.