Summary

Background and objective: Combined spinal–epidural (CSE) anaesthesia may be performed using separate needles or by passing the spinal needle through an epidural needle. The latter technique requires that subarachnoid block is performed before the epidural catheter is placed. This paper examines a series of 201 consecutive CSEs performed with a novel separate needle technique, designed to avoid potential and actual problems associated with the CSE technique.

Methods: The CSE technique involved placement of the spinal needle in the subarachnoid space, followed by replacement of the spinal needle stylet. The epidural catheter was then positioned separately before returning to the spinal needle and injecting the subarachnoid drug.

Results: The technique had a high technical success rate. Both needles were successfully placed in 200 (99.5%) cases. Spinal anaesthesia was successful in all cases. The epidural catheter was used in 179 cases and failure of the epidural occurred in 2 (1.1%) cases. Paraesthesia, inability to advance the epidural catheter or blood in the epidural catheter occurred in 31 (15.4%) and necessitated immediate replacement of the epidural catheter in 14 (7%) cases. Postoperatively, typical post-dural puncture headache was reported by one patient (0.5%) and mild backache by four (2%). There were no neurological complications.

Conclusions: This method of CSE anaesthesia can be associated with high success and low complication rates.

Summary

Background and objective: To evaluate the capability of first responders to ensure an airway and ventilate the lungs of a patient employing a bag-valve device and two oxygen-driven resuscitators.

Methods: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300® devices, with 20 cmH2O working pressure, flows of 24 and 30 L min−1. One-hundred-and-four patients were analysed. Induction of anaesthesia was followed by ventilation of the lungs with a bag-valve device and an Oxylator® (CPR Medical Devices Corp., Markham, Ontario, Canada) in manual and automatic modes. Each series was repeated twice by a fireman first responder using a hand-held mask to seal the airway, once under anaesthesia and then again under anaesthesia with muscle relaxation.

Results: Patients’ mean age 49 ± 17 yr; 47% male, 48–132 kg. Only 29% had optimal facial and airway physiognomy. Airway management was significantly poorer when the bag-valve device was used than with either Oxylator® mode (P < 0.0001); 23% of cases were not manageable with the bag-valve device. Gastric insufflation was markedly less with the Oxylator® (P < 0.02).

Conclusions: The use of an oxygen-driven device improves the ability of first responders to secure an airway and reduce gastric insufflation, even when distracted. Oxylators® perform significantly better (P < 0.0001) than the bag-valve device.

Summary

Background and objective: Both the bispectral and the patient state indices are derived from the electroencephalogram and have been proposed as a measure of the same clinical target, the hypnotic component of anaesthesia. The present study evaluated whether there is concordance between the bispectral and the patient state indices with regard to end-points measured simultaneously in patients undergoing surgery under general anaesthesia.

Methods: Fifty-seven patients scheduled for elective abdominal, orthopaedic (Groups 1 and 2) or cardiac surgery (Group 3) under general anaesthesia were enrolled in the study. Anaesthesia was performed using remifentanil/sevoflurane (Group 1, 19 patients), remifentanil/propofol (Group 2, 19 patients) or sufentanil/propofol/isoflurane (Group 3, 19 patients). The bispectral and the patient state indices were simultaneously recorded. Pearson’s correlation between these two indices was calculated for the complete data and each group. The percentage of bispectral index values in the recommended range for general anaesthesia (45–60) that were confirmed by levels of patient state index (25–50) was calculated and vice versa.

Results: Overall correlation between the bispectral and the patient state indices was 0.667, 0.671 in Group 1, 0.650 in Group 2 and 0.675 in Group 3 (P < 0.01). For values of the bispectral index between 45 and 60, only 40% of corresponding patient state index values were between 25 and 50. For patient state index values of 25–50, only 50% of the corresponding bispectral index values were in the range of 45–60.

Conclusions: Concordance between the bispectral and patient state indices is relatively weak, whereas both are thought to reflect the same clinical target, the hypnotic component of anaesthesia. As a consequence, further studies are required to compare reliability of both indices as indicators of different levels of hypnosis.

Summary

Background and objective: In cases of aspiration of gastric contents the risk of pneumonitis is dependent on the pH and volume of the gastric contents. Omeprazole and rantidine each decrease gastric volume and increase gastric pH. We evaluated the efficacy of preoperative administration of omeprazole (60 mg) or ranitidine (150 mg) in the prophylaxis of aspiration pneumonitis.

Methods: Data were obtained from 75 elective female surgical patients randomly allocated to one of three groups, who received either omeprazole 60 mg orally, or ranitidine 150 mg orally, or neither, on the evening prior to, and on the morning of, surgery. Gastric volume and pH was measured using blind aspiration.

Results: Both pH <2.5 and volume >25 mL were present in none of the patients in either the ranitidine or omeprazole groups, compared to 15 of 25 control patients (P < 0.0001).

Conclusions: Preoperative oral administration of omeprazole (60 mg) or ranitidine (150 mg) reduced residual gastric content volume and increased pH >2.5, possibly reducing the effects of pulmonary aspiration of gastric contents.

Summary

In this review paper, the authors critically analyse the use of a number of depth of anaesthesia monitors in light of the most recent literature and their own clinical experience. There appears to be increasing evidence that anaesthesia depth monitors reduce the incidence of unexpected intraoperative awareness and also that they improve the quality of anaesthesia. Proper use of these monitors necessitates background knowledge about the physiology of the loss of consciousness, the type of variable recorded and processed by the monitoring devices, the factors that might interfere with recording and the limits of use. The information provided by anaesthesia depth monitors is detailed and relationships with clinical practice are established to provide the reader with key features for optimal use of those monitors and correct interpretation of data. Practitioners and patient's knowledge and expectations regarding this matter, as well as the cost–benefit relationship are also discussed.

Summary

Background and objective: To evaluate the capability of first responders to achieve and maintain normal ventilation of the lungs of victims employing a bag-valve device and two oxygen-driven resuscitators.

Methods: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300® devices, with 20 cmH2O working pressure, and flows of either 24 or 30L min−1. One hundred and four patients were analysed. Induction of anaesthesia followed by ventilation of the lungs with a bag-valve device and an Oxylator® in manual and automatic modes performed by a fireman first responder. Each series was repeated for three conditions (anaesthesia; anaesthesia plus muscle relaxation, both with facemask; anaesthesia plus relaxation using an endotracheal tube).

Results: Patients age 49 ± 17 yr; 47% males, 48–132 kg. Normocapnia was achieved and maintained in 66% (bag-valve device), 82% (Oxylator®).

Conclusions: The use of an oxygen-driven device improves the ability of first responders to achieve and maintain normocapnia even when distracted. Use of the Oxylators® improves performance (P < 0.001) vs. the bag-valve device significantly.

Summary

Background and objective: This prospective, randomized and blinded study compared the performance of a new needle-through-needle (NTN) kit (Epistar®; Medimex, Germany) with the double-space technique for providing combined spinal epidural anaesthesia during Caesarean section.

Methods: Following local Ethics Committee approval and patient consent, 200 females were randomized to receive combined spinal epidural anaesthesia by the double-space (n = 100) or NTN (n = 100) technique. The frequency with which the intrathecal component could achieve a T5 block to touch for Caesarean section without the need for epidural augmentation or an alternative technique was determined. The time from start of procedure to achieving a block height to T5 was recorded. Pain and backache at insertion, and at 24 h follow-up were recorded using a visual analogue scale. To remove any bias due to posture, 50% of each group were further randomized to receive their block in the sitting or in the left lateral position. To evaluate improvement of performance over time the success in the first 100 study patients were compared to the success in the second 100.

Results: A successful block to T5 with the double-space and NTN techniques were 80 vs. 54, odds ratio 0.29. Failure to enter the intrathecal space once the epidural space had been located occurred in 29 patients in the NTN group. Time to readiness for surgery was 15 min (95% confidence interval (CI): 12.7–17.4) and 12.9 min (95% CI: 11.5–14.3) for the double-space and NTN techniques, respectively. The median (interquartile range) visual analogue scores for discomfort at insertion were 30 (12.5–51.5) and 32 (12.75–60) and for postoperative backache 0 (0–10) and 0 (0–10.75) in the double-space and NTN groups, respectively. The number of epidural augmentations was similar in both the groups and posture made no difference. There was a tendency to increased success in the second half of the study.

Conclusion: The double-space technique had a greater success rate than the NTN technique.

Summary

Background and objective: Venous air embolism is a constant threat during neurosurgery performed in the sitting position. No large prospective study has compared the incidence of venous air embolism and associated hypotension between adults and children.

Methods: Four hundred and thirty patients (334 adults, 96 children) scheduled to undergo planned posterior fossa surgery in the sitting position (between January 1989 to December 1994) were studied with end-tidal carbon dioxide monitoring. Intraoperatively, a sudden and sustained decrease in end-tidal carbon dioxide tension of >0.7 kPa was presumed to be due to venous air embolism. Management during the episode was on the established guidelines. Hypotension (decrease in systolic arterial pressure of 20% or more from the previous level) was treated with crystalloids and/or a vasopressor.

Results: Capnometry detected a 28% incidence rate of air embolism in adults (93/334) and a 22% incidence rate in children (21/96) (P = 0.29). In both groups, the highest incidence rate of embolism took place during muscle handling (44% of adults versus 38% of children, P = 0.8). Embolic episodes were accompanied by hypotension in 37% of adults (34/93) and in 33% of children (7/21) (P = 0.98). To restore arterial pressure to pre-embolic levels, 53% of adults (18/34) and 43% of children (3/7) were administered vasopressors (P = 0.94). There was no intraoperative mortality. The surgical procedure on one adult was abandoned because of persistent hypotension following the embolic episode.

Conclusion: The incidence of venous air embolism and consequent hypotension is similar in adults and children.

Summary

Background and objective: Although electrocardiography (ECG) guidance of central venous catheters (CVCs) is traditionally thought to detect the entrance into the right atrium (RA), there is little evidence in the literature to confirm this. We previously observed a high incidence of left-sided CVCs abutting the wall of the superior vena cava (SVC), even when the catheters were advanced past the point of increased P-wave amplitude. Our hypothesis was that this ECG amplitude signal is actually detecting the pericardial reflection rather than the RA. The goal of the study was to position catheter tips under ECG guidance outside the RA.

Methods: One-hundred central venous triple-lumen catheters inserted either via the right or the left internal jugular veins, respectively, were analysed in cardiac surgical patients. The position of the catheter tip was ascertained by ECG. Method A: A Seldinger guide-wire in the distal lumen served as exploring electrode, the respective insertion depth was recorded. Method B: The middle lumen (port opening 2.5 cm from the catheter tip, thus the catheter was advanced more towards the atrium) filled with a saline 10% fluid column served as the exploring electrode, and the insertion depth was recorded again. Descriptive data are given as mean ± standard deviation.

Results: On average, the catheters were advanced by the expected 2 ± 0.3 cm using Method B beyond the initial insertion by Method A. All 100 CVCs were finally correctly positioned in the SVC and confirmed by transoesophageal echocardiography. When chest radiography was performed after surgery not a single catheter abutted the lateral wall of the SVC.

Conclusion: Since both methods detected the same structure, and catheters placed by Method B did not result in intra-atrial CVC tip position, the first increase in P-wave amplitude does correspond to a structure in the SVC, most likely the pericardial reflection.

Summary

Background and objective: Former studies revealed conflicting information on the usefulness of intraoperative monitoring of visual evoked potentials. This study was designed to evaluate the characteristics of visual evoked potential recording in surgically anaesthetized patients using the modality of steady-state visual evoked potentials.

Methods: In 30 cases with non-cranial surgery steady-state visual evoked potentials were recorded in the awake and surgically anaesthetized patient using total intravenous anaesthesia. For stimulation, goggles with red light-emitting diodes at a frequency of 8.5 Hz were used. A two-channel recording with silver cup electrodes at Oz to Fz and Oz to earlobe was used. All traces were analysed for the presence of the characteristically sinusoidal waveform and amplitudes and latencies of the main peaks were measured.

Results: Recordings during surgery demonstrated a minor latency prolongation of 16% and a more pronounced amplitude attenuation of 67% compared to the recordings in the awake patients. These differences were statistically significant (paired t-test, P < 0.001). In surgically anaesthetized patients steady-state visual evoked potentials showed a relatively high intra- and interindividual variability. In four of 30 patients completely stable recordings were obtained, whereas in 14 patients identifiable waves were recordable in only less than 50% of the intraoperative traces. Of the total 1360 traces recorded intraoperatively clearly identifiable steady-state visual evoked potentials patterns were present in 56% of the traces. There was no correlation between the magnitude of the evoked potential amplitude and its stability in intraoperative recordings.

Conclusions: We conclude from this study, that steady-state visual evoked potential recordings in the surgically anaesthetized patient appeared to be more stable compared to our earlier findings using transient visual evoked potentials. However, further efforts are necessary to improve the stability of the recordings during surgery and thus allow for a more reliable intraoperative monitoring of visual pathways in routine clinical practice.

Summary

Background and objective: The clinical practice of spinal morphine administration for pain relief is based on observations in animals that opioid receptors exist in the spinal cord and intrathecal injections of opioids in those species (mostly rats) lead to antinociceptive effects. Clinicians are well aware that administration of spinal opioids is associated with side-effects, such as nausea and respiratory depression, that indicate supraspinal spread of the drug administered. Those observations call into question how much of the observed pain relief is due to action of the drug in the brain. This study investigated the spinal cord actions of morphine given intrathecally to rats in a model that allows investigation of drug–receptor interaction at the spinal cord level. Experiments were performed on male Wistar rats with chronically implanted lumbar subarachnoid catheters.

Methods: Nociceptive thresholds were measured in rats given morphine intrathecally alone and in combination with intrathecal injections of selective opioid receptor antagonists: β-funaltrexamine (μ), naltrindole (δ) and nor-binaltorphimine (κ).

Results: Intrathecal morphine caused dose-related antinociceptive effects that were reversed totally by naloxone. Intrathecal β-funaltrexamine and naltrindole did not reverse the effects of intrathecal morphine. However, intrathecal nor-binaltorphimine did reverse the electrical current threshold effects of morphine but not tail flick latency.

Conclusions: Antinociception following intrathecal morphine involves spinal and supraspinal opioid receptors. The tail flick effect described in rat experiments involves actions at opioid receptors in the brain that override any action that may be caused by combination of morphine with μ-opioid receptors in the spinal cord.

Summary

Background and objective: The main purpose of this study was to investigate the effects of sensory (acupressure and acupuncture) and optical stimulation (Laserneedle® acupuncture) on electroencephalographic bispectral index, spectral edge frequency and a verbal sedation score.

Methods: Twenty-five healthy volunteers (mean age ± SD: 25.5 ± 4.0 yr) were investigated during the awake state. The acupuncture point Yintang and a placebo control point were stimulated. The study was performed as a randomized, controlled and partly blinded cross-over trial.

Results: Bispectral index and spectral edge frequency values both decreased significantly (P < 0.001) during acupressure on Yintang to values of 62.9 (minimum 35) ± 13.9 bispectral index and to 13.3 (minimum 2.9) ± 8.1 Hz (spectral edge frequency right) and 13.8 (minimum 2.7) ± 7.3 Hz (spectral edge frequency left), respectively. Bispectral index was also significantly (P < 0.05) affected by Laserneedle® acupuncture and acupressure on the control point but the changes were not clinically relevant, 95.4 ± 4 and 94.2 ± 4.8, respectively. All interventions significantly (Yintang: P < 0.001; control point: P < 0.012) reduced verbal sedation score.

Conclusions: The study highlights the electroencephalographic similarities of acupressure induced sedation and general anaesthesia as assessed by bispectral index and spectral edge frequency.

Summary

Background and objective: A multicentre study was conducted to compare three methods of inhalation induction with sevoflurane in adult premedicated patients.

Methods: One-hundred-and-twenty-five adult patients of ASA I–II were scheduled for short elective surgical procedures (<90 min) under general anaesthesia with spontaneous ventilation of the lungs via a laryngeal mask airway. Patients were randomly assigned to one of three groups: conventional stepwise inhalation induction group (Group C) or vital capacity rapid inhalation induction groups at 4.5% (Group VC4.5) or at 8% sevoflurane (Group VC8). Before anaesthetic induction, fentanyl 1 μg kg−1 was given and the face mask applied with the anaesthetic breathing system primed with sevoflurane 4.5% or 8% in the respective vital capacity groups. Loss of eyelash reflex, time to cessation of finger tapping, laryngeal mask insertion, side-effects and adequacy of induction were recorded.

Results: The time to loss of eyelash reflex was significantly shorter in both vital capacity groups vs. the control group: VC8: 68 ± 7 s; and VC4.5: 94 ± 6.5 s vs. C: 118 ± 6.4 s (P < 0.0001). Significant differences were found in all pairwise comparisons for time to cessation of tapping: Group VC8 (62 ± 7 s), Group VC4.5 (85 ± 6 s) and Group C (116 ± 6 s; P < 0.0001). The time to laryngeal mask insertion was significantly shorter in the Group VC8 (176 ± 13 s) compared with the other two groups, Group VC4.5 (219 ± 13 s) and Group C (216 ± 9 s). There were no significant differences in the incidence of side-effects between the three groups.

Conclusions: Inhalation induction of anaesthesia with sevoflurane with the three techniques tested is safe, reliable and well accepted by the patients. The vital capacity rapid inhalation group primed with sevoflurane 8% was the fastest method with no relevant side-effects.

Summary

Background and objective: It is important to provide good postoperative analgesia after discharge from day case surgery. The usefulness of intra-articular morphine for analgesia after day case knee arthroscopy remains controversial. A large dose of morphine intra-articularly may provide a good long-lasting analgesia, but its efficacy and pharmacokinetics are not known and may be no better than intramuscular morphine. We compared the effect of 10 mg intra-articular and intramuscular morphine for 24 h post-injection in a randomized double-blind study.

Methods: Forty adults undergoing knee arthroscopy were recruited and received either 10 mg morphine intra-articularly or intramuscularly. Our primary outcome was overall visual analogue assessment of pain (0–100 mm scale where 0 is no pain and 100 is worst possible pain) between 4 h (on discharge) and 24 h (postoperatively). Plasma morphine concentrations were measured at 15 min, and 1, 2, 4 and 24 h. The use of additional analgesia was noted.

Results: The assessment of pain experienced between discharge (4 h) and 24 h was significantly better in the intra-articular (n = 20; mean ± SD: 18 ± 19) than the intramuscular (n = 19; mean ± SD: 34 ± 20) group (P = 0.027). The number of patients consuming any additional analgesia between discharge and 24 h was significantly lower in the intra-articular morphine group (P = 0.038), with 4 (20%) patients in the intra-articular group and 11 (60%) patients in the intramuscular group consuming supplementary analgesia. There were no differences in plasma morphine concentrations between the groups.

Conclusions: A large dose of intra-articular morphine provided better analgesia than the same dose of intramuscular morphine, low plasma morphine levels suggesting a peripheral mechanism.

Summary

Background and objective: To evaluate the efficacy of 0.1% ropivacaine with fentanyl 2 μg mL−1 via epidural for analgesia in labour.

Methods: In a randomized study, 80 nulliparous parturients in labour had epidural analgesia initiated with 0.2% ropivacaine and fentanyl and were then randomized to receive either 0.1% ropivacaine with fentanyl 2 μg mL−1 at 10 mL h−1 (Group R1, n = 38) or 0.2% ropivacaine with fentanyl 2 μg mL−1 at 8 ml h−1 (Group R2, n = 39) as epidural infusions. Supplementary analgesia was provided on request with ropivacaine 0.2% 5 mL as an epidural bolus.

Results: There were no significant differences between the visual analogue pain scores either with respect to motor block or sensory block. The amount of local anaesthetic used was lower in the 0.1% ropivacaine group than in the 0.2% ropivacaine group (P = 0.001). Side-effects, patient satisfaction, labour outcome and neonatal outcomes were similar in both groups.

Conclusions: An epidural infusion of 0.1% ropivacaine with fentanyl 2 μg mL−1 at 10 mL h−1 provided adequate analgesia in the first stage of labour. The level of analgesia was similar to that obtained using 0.2% ropivacaine with fentanyl 2 μg mL−1 and with no differences with regard to motor or sensory block.

Summary

Background and objective: To compare the effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing elective non-ophthalmic surgery.

Methods: Thirty-two patients (ASA I–II) were randomized into two groups to receive either a continuous infusion of remifentanil (0.25–0.5 μg kg−1 min−1, n = 16, Group R) or an intermittent bolus of fentanyl (2–5 μg kg−1, n = 16, Group F) during the maintenance of anaesthesia. For the induction of anaesthesia, Group R received remifentanil 1 μg kg−1 and Group F received fentanyl 2 μg kg−1; both groups then received propofol 2 mg kg−1 with vecuronium 0.1 mg kg−1. Anaesthesia in both groups was maintained with a continuous infusion of propofol 4–8 mg kg−1 h−1. Ventilation of the lungs was controlled to a constant end-tidal PCO2 of 4.7–5.4 kPa. Blood pressure, electrocardiography, heart rate and oxygen saturation were monitored throughout anaesthesia. Intraocular pressure was determined before surgery, during the maintenance of anaesthesia, 2 min after emergence and in the recovery room using a Perkins hand-held applanation tonometer by an ophthalmologist blinded to the anaesthetic technique.

Results: After induction of anaesthesia, a significant decrease in intraocular pressure in the remifentanil group from 13.6 ± 2.6 to 7.1 ± 3.1 mmHg (P < 0.001) and in the fentanyl group from 13.7 ± 2.2 to 9.7 ± 3.4 mmHg (P < 0.001) was observed and maintained during anaesthesia. Thirty minutes after the end of anaesthesia, intraocular pressure returned to baseline values in both groups (remifentanil: 13.9 ± 2.8 mmHg, P = 0.28; fentanyl: 13.6 ± 2.3 mmHg, P = 0.59). The intraocular pressure and haemodynamic variables did not differ significantly between the two groups (intraocular pressure, P = 0.7327; blood pressure, P = 0.1295; heart rate, P = 0.8601).

Conclusions: Remifentanil maintains intraocular pressure at an equally reduced level compared with fentanyl.

Summary

Background and objective: Catheterization of the internal jugular vein is traditionally performed with the patient lying flat or in the Trendelenburg position. This puts patients with elevated intracranial pressure at risk of cerebral herniation. The objective of this study was to assess the safety of real-time ultrasound-guided catheterization of the internal jugular vein in ventilated patients with the patient positioned in a 30° head-up position.

Methods: This prospective, single-centre case series was performed in a 12-bed multi-disciplinary adult intensive care unit (ICU) in a 1500-bed university hospital. The cohort consisted of 64 ventilated ICU patients (14 female, 50 male) with a median age of 52 yr (range 18–85 yr), needing central venous cannulation for insertion of a central venous, haemodialysis or pulmonary artery catheter. The majority of patients presented with risk factors for a difficult cannulation. Catheterization was performed using real-time ultrasound guidance with all patients positioned in 30° dorsal elevation.

Results: Ultrasound-guided cannulation of the internal jugular vein was successful in all patients. There was no evidence of air embolism. Despite a high incidence of anomalous anatomy (39%) no injury to the carotid artery occurred. Central venous access was established in less than 1 min in 75% of patients.

Conclusion: Ultrasound-guided cannulation of the internal jugular vein in ventilated ICU patients can be performed successfully with the patient positioned in 30° dorsal elevation. Potentially deleterious position changes can thus be avoided in high-risk patients.

Summary

Background and objective: In 1991 general anaesthesia was used extensively for emergency Caesarean section at Haukeland University Hospital even in patients with an ongoing epidural infusion. With increased knowledge of the potential safety benefits of regional anaesthesia and increased experience with the technique, we decided to use indwelling epidural catheters for emergency Caesarean section.

Methods: We conducted a retrospective analysis of a full annual data set on emergency Caesarean section in parturients with ongoing epidural analgesia in 1997 and compared it with a similar data set from 1991.

Results: Epidural anaesthesia was used significantly more often in 1997 with 115 (78%) cases than in 1991 with five (12%) cases (P < 0.001). Elapsed time before adequate anaesthesia and the start of surgery was significantly shorter in 1991 (mean 8.3 min) compared to 1997 (mean 13 min) (P < 0.001). No deaths or major complications were observed in either group. Intraoperative minor complications were observed more frequently in 1997 with 70 cases (47%) than in 1991 with two cases (6%) (P < 0.001). The principal complications were hypotension and nausea. Postoperative complications in mother and neonate were similar in both groups. There was a significantly shorter mean hospital stay in 1997 (6 days), compared with 1991 (8 days) (P < 0.001).

Conclusion: The increase in the use of indwelling epidural catheters for emergency Caesarean section has resulted in a significant increase in the use of regional anaesthesia. A modest increase in time elapsed before start of surgery was observed although there were no significant differences in the number of neonates with low Apgar scores. No major complications were observed, but there was an increased frequency of minor complications in 1997.

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.