Besides the fast tetrodotoxin-sensitive Na+ current, small dorsal root ganglion neurones of rats also possess a slower tetrodotoxin-resistant Na+ current. The blocking effect of commonly used local anaesthetics upon the tetrodotoxin-resistant Na+ current was investigated in the present paper. Dorsal root ganglia were dissected from adult rats and cells were enzymatically isolated. The whole-cell patch clamp technique was then used to measure inward Na+ currents of small dorsal root ganglion neurones. Externally applied local anaesthetics reversibly blocked the tetrodotoxin-resistant Na+ current in a dose-dependent manner. Half-maximal blocking concentrations for tonic block were: lignocaine, 326 μm; prilocaine, 253 μm; mepivacaine, 166 μm; etidocaine, 196 μm bupivacaine, 57 μm procaine, 518 μm benzocaine, 489 μm; tetracaine, 21 μm; and dibucaine, 23 μm. Blocking of the current by lignocaine was independent of temperature. The quaternary lignocaine derivative QX-314 did not have any effect upon the tetrodotoxin-resistant Na+ current when applied externally. High concentrations of tetrodotoxin also blocked the tetrodotoxin-resistant Na+ current with a half-maximal blocking concentration of 115 μm. The block by high tetrodotoxin concentrations did not compete with the lignocaine block, suggesting that there were two independent blocking mechanisms for the two substances. The tetrodotoxin-resistant Na+ currents also showed a marked sensitivity to phasic (use-dependent) block by local anaesthetics.

The TOF-GUARD™ is a new device for monitoring the neuromuscular function using acceleration measurement. It is quick and easy to apply and does not require a rigid support for the arm. Forty-one patients were studied to assess the monitoring of vecuronium neuromuscular block (NMB) using accelerography by the TOF-GUARD™ compared with electromyography by the Relaxograph®. Although the mean first twitch (T1%) and mean train-of-four (TOF) ratios measured by the TOF-GUARD™ corresponded to a certain extent with the Relaxograph®, the wide variations of the values for individual patients measured by the TOF-GUARD™ compared with the Relaxograph® and the differences in clinical duration and recovery index between the two monitors do not allow the values of the two monitors to be used interchangeably. The levels at intubation as well as at full recovery of the patients can be assessed equally by the two monitors. Thus, the TOF-GUARD™ is a reliable clinical monitor in daily anaesthesia practice.

Summary

Background and objective: Effective and early treatment of postoperative pain and nausea have become pivotal for the early discharge of patients after tonsillectomy. Opioid-based analgesia is standard practice but the use of non-steroidal anti-inflammatory drugs is discouraged due to their platelet inhibiting properties. The cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drugs are effective analgesics and do not affect platelet function. We hypothesized that premedication with cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drug in addition to paracetamol would provide effective analgesia and decrease opioid consumption during early recovery from tonsillectomy. Methods: In a randomized, placebo-controlled study of adult tonsillectomy patients (n = 40) one group (R-group; n = 20) was premedicated with paracetamol 1.5 g and rofecoxib 50 mg and a control group (P-group; n = 20) was premedicated with paracetamol 1.5 g and placebo. Morphine was used as rescue medication. Postoperative (24 h) pain scores (0–10), morphine consumption as well as intraoperative blood loss were recorded. Results: We found no overall difference in pain scores between the groups but significantly more patients in the placebo group had pain scores >5 within the first 8 h. The rofecoxib group consumed less morphine during the first 12 h. A lower intraoperative blood loss was observed in the rofecoxib group. Conclusion: Our results suggest an early although clinically minor analgesic benefit of the addition of a cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drug to paracetamol as premedication for adult tonsillectomy.

Background and objective: To assess the publication rate of full papers presented as abstracts at the 1995 meeting of the European Society of Anaesthesiologists, and to assess factors that might predict subsequent full publication.

Methods: All abstracts presented at the meeting and published in the British Journal of Anaesthesia (Suppl 1, 1995) were included. To verify subsequent full publication, a MEDLINE search was performed and validated. We studied the average time from the meeting to publication, the first author's country, the subspeciality, the publishing journal of the full report, the type of presentation (oral or poster), the object of investigation, and the quality of research design and of statistical reporting in the abstract.

Results: Of 472 meeting abstracts, 199 (42.2%) were eventually published. The average (± SD) delay between meeting and publication was 16.8 (15.6) months (range 24–60 months). Most papers (79.4%) had been published within 3 yr of the meeting. Circulation, pharmacology and intensive care papers had the highest rates of publication. Sixty-three journals attracted papers, with the British Journal of Anaesthesia publishing most (n = 29). No difference in subsequent publication was found between oral and poster presentations. Randomized trials and animal research were more likely to be published. The number of authors or their positions differed between the abstract and the full publication in 145 cases (72.9%); the first author was changed in 43 cases.

Conclusions: Less than half of the abstracts accepted at the 1995 European Society of Anesthesiologists' meeting were subsequently published in journals indexed by MEDLINE in the 3 yr following the meeting. Many changes in authorship occurred between the abstract and the full publication. The study architecture and the object of investigation predicted full publication.

Summary

Subarachnoid haemorrhage due to rupture of cerebral aneurysms is a multisystem disease. Treatment of the condition in the past has relied on craniotomy and clipping of the aneurysm to prevent a recurrent haemorrhage. There is now emerging evidence to suggest that endovascular treatment of cerebral aneurysms may reduce the morbidity associated with open surgery. The anaesthetic management of interventional neuroradiology also creates new challenges due to the novel approach to treatment. Anaesthetists need to be familiar with this procedure and the management of potential complications. This review provides an overview such considerations.

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: We conducted a prospective randomized study to evaluate whether the duration of action of a single bolus dose of rocuronium is influenced by maintenance of anaesthesia with sevoflurane, desflurane or propofol infusion.

Methods: Fifty-seven ASA I–II patients undergoing elective abdominal surgery were enrolled in this study. Anaesthesia was induced with thiopental 3–5 mg kg−1 or propofol 2.5 mg kg−1 and fentanyl 5 μg kg−1 and tracheal intubation was facilitated with rocuronium 0.9 mg kg−1. Thereafter patients were randomly allocated to three different groups to receive sevoflurane, desflurane or propofol for maintenance of anaesthesia. Recovery of neuromuscular function was monitored by single twitch stimulation of the ulnar nerve and by recording the adductor pollicis response using accelerometry. Intergroup recovery times to 5% of control value of single twitch were analysed using analysis of variance with Bonferroni correction.

Results: The mean (95% confidence interval) recovery time to 5% of control value of single twitch during desflurane anaesthesia was 90.18 (86.11–94.25) min. Significantly shorter recovery times were observed during sevoflurane or propofol anaesthesia, 58.86 (54.73–62.99) min and 51.11 (45.47–56.74) min, respectively (P < 0.001). There were also significant differences in the recovery time between groups receiving desflurane vs. sevoflurane (P < 0.001) and desflurane vs. propofol (P < 0.001).

Conclusions: Desflurane anaesthesia significantly prolongs the duration of action of rocuronium at 0.9 mg kg−1 single bolus dose, compared to sevoflurane or propofol anaesthesia maintenance regimens.

Summary

Background and objective: Stellate ganglion block has been extensively used in clinical practice for the management of painful conditions such as cephalic, facial and upper limb pains yet its mechanism of action and its analgesic efficacy are poorly understood. Method: Formalin (3% 0.2 mL) was injected into the plantar region of the right upper limb paw in rabbits and 50 min after this injection, saline or bupivacaine 2.5% 0.5 mL was administered via a chronic implantation catheter near the right stellate ganglion. Behavioural modification, changes in heart rate and plasma norepinephrine release at different time points after formalin and bupivacaine or saline injection were observed. Finally, the cervical spinal cord was harvested and immunostaining for substance P and c-Fos was performed. Results: Formalin caused stress noxious behavioural changes and a significant increase in heart rate and norepinephrine release. These changes were inhibited by bupivacaine stellate ganglion block but not by saline injection. Immunoreactants of substance P were significantly decreased by formalin injection compared with that in controls. However, with bupivacaine injection, substance P levels were restored though not reaching the levels seen in the controls. Formalin injection also caused a significant increase of c-Fos expression in cervical spinal cord. This increase was not affected by stellate ganglion block. Conclusion: Stellate ganglion block can effectively alleviate nociceptive responses induced by formalin injection. The mechanism of its action may involve reduction of substance P in the spinal cord and plasma catecholamine release caused by noxious stimuli.

Summary

Background and objective: We conducted this study in order to evaluate the potential myotoxic effects of ropivacaine after single injection in rats and the time-course of the possible damage. Methods: One hundred and twenty-eight male Wistar rats were allocated to four different groups. The first three groups received intramuscular injections with ropivacaine 0.75%, ropivacaine 0.5% and normal saline, respectively, into the right tibialis anterior muscle. The fourth group received needle puncture without injection. Eight rats from each group were sacrificed 2, 4, 7 and 30 days after injection. Samples were blindly examined under light microscope for evidence of myotoxicity, scored as 0 = no damage to 3 = myonecrosis and statistically analysed. Samples obtained 7 days after injection were also examined under transmission electron microscope. Results: Ropivacaine 0.75% and ropivacaine 0.5% caused extensive destruction to muscles fibres, compared to saline or needle on days 2, 4 and 7. Statistically significant differences were found in muscle damage by drug injections among all groups except for saline vs. needle groups. Thirty days after injections all sample appearances had returned to normal. Conclusions: Ropivacaine after single intramuscular injection caused reversible muscle damage in a dose-dependent manner.

Summary

Background and objective: The GlideScope® videolaryngoscope is a newly developed laryngoscope for tracheal intubation recently introduced into clinical anaesthesia. In this randomised clinical study, we compared the haemodynamic responses to orotracheal intubation using a GlideScope® videolaryngoscope and a fibreoptic bronchoscope. Methods: Fifty-six adult patients, ASA I–II scheduled for elective plastic surgery under general anaesthesia requiring orotracheal intubation were randomly allocated to either the GlideScope® videolaryngoscope group or the fibreoptic bronchoscope group. After a standard intravenous anaesthetic induction, orotracheal intubation was performed. Noninvasive blood pressure and heart rate were recorded before and after induction, at intubation and for 5 min after intubation at 1 min intervals. Results: As compared with the post-induction values the orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope resulted in the significant increases in blood pressures which did not exceed their baseline values. In the two groups, heart rates at intubation and within 2 min after intubation were significantly higher than their baseline values. However, there were no significant differences in blood pressures and heart rates at all time points, their maximal values and maximal percent changes during the observation and the times required to reach their maximal values between the two groups. Conclusions: The orotracheal intubations using a fibreoptic bronchoscope and a GlideScope® videolaryngoscope produce similar haemodynamic responses.

Summary

Background and objective: We conducted a study investigating the effectiveness of four face mask designs in the bag-mask ventilation of a special manikin adapted to simulate a difficult airway. Methods: Forty-eight anaesthetists volunteered to bag-mask ventilate the manikin for 3 min with four different face masks. The primary outcome of the study was to calculate mean percentage leak from the face masks over 3 min. Anaesthetists were also asked to rate the face masks using a visual analogue score. Results: The single-use scented intersurgical face mask had the lowest mean leak (20%). This was significantly lower than the mean leak from the single-use, cushioned 7000 series Air Safety Ltd. face mask (24%) and the reusable silicone Laerdal face mask (27%) but not significantly lower than the mean leak from the reusable anatomical intersurgical face mask (23%). Conclusions: There was a large variation in both performance and satisfaction between anaesthetists with each design. This highlights the importance of having a variety of face masks available for emergency use.

Summary

Electromagnetic interference produced by wireless communication can affect medical devices and hospital policies exist to address this risk. During the transfer of ventilated patients, these policies may be compromised by essential communication between base and receiving hospitals. Local wireless networks (e.g. Bluetooth®) may reduce the ‘spaghetti syndrome’ of wires and cables seen on intensive care units, but also generate electromagnetic interference. The aim of this study was to investigate these effects on displayed and actual ventilator performance. Methods: Five ventilators were tested: Drager Oxylog 2000, BREAS LTV-1000, Respironics BiPAP VISION, Puritan Bennett 7200 and 840. Electromagnetic interference was generated by three devices: Simoco 8020 radio handset, Nokia 7210 and Nokia 6230 mobile phone, Nokia 6230 communicating via Bluetooth with a Palm Tungsten T Personal Digital Assistant. We followed the American National Standard Recommended Practice for On-Site, Ad Hoc Testing (ANSI C63) for electromagnetic interference. We used a ventilator tester, to simulate healthy adult lungs and measure ventilator performance. The communication device under test was moved in towards each ventilator from a distance of 1 m in six axes. Alarms or error codes on the ventilator were recorded, as was ventilator performance. Results: All ventilators tested, except for the Respironics VISION, showed a display error when subjected to electromagnetic interference from the Nokia phones and Simoco radio. Ventilator performance was only affected by the radio which caused the Puritan Bennett 840 to stop functioning completely. The transfer ventilators' performance were not affected by radio or mobile phone, although the mobile phone did trigger a low-power alarm. Effects on intensive care ventilators included display reset, with the ventilator restoring normal display function within 2 s, and low-power/low-pressure alarms. Bluetooth transmission had no effect on the function of all the ventilators tested. Conclusion: In a clinical setting, high-power-output devices such as a two-way radio may cause significant interference in ventilator function. Medium-power-output devices such as mobile phones may cause minor alarm triggers. Low-power-output devices such as Bluetooth appear to cause no interference with ventilator function.

Summary

Background and objective: The target effect-site concentration of propofol to insert a laryngeal mask airway was recently reported as almost 5 μg mL−1. The present study aimed to determine the target effect-site concentration with target-controlled infusion of propofol to place classical larnygeal mask airway or current laryngeal tube in adult patients. Methods: We included 40 patients scheduled for short gynaecological and radiological procedures under general anaesthesia in a randomized, double-blind manner using the Dixon's up-and-down statistical method. Monitoring included standard cardiorespiratory monitors, and bispectral index monitoring was used for all patients. Anaesthesia was conducted with a target-controlled infusion system: Diprifusor™. The initial target plasma concentration of propofol was 5 μg mL−1, and was changed stepwise by 0.5 μg mL−1 increments according to Dixon's up-and-down method. Criteria for acceptable insertion were: Muzi's score ≤2, and mean arterial blood pressure, heart rate or bispectral index variation <20% the baseline values.Results: Target effect-site concentration of propofol required to insert laryngeal tube was 6.3 ± 0.3 μg mL−1 with Dixon method and ED50 was 6.1 μg mL−1 (5.9–6.4) with logistic regression method. In the case of larnygeal mask airway they were 7.3 ± 0.2 μg mL−1 (Dixon method) and 7.3 μg mL−1 (7.1–7.5; with logistic regression) respectively (P < 0.05). ED95 (logistic regression) was 6.8 μg mL−1 (5.9–7.6) for laryngeal tube and 7.7 μg mL−1 (7.3–8.0) for larnygeal mask airway (P < 0.05). Haemodynamic incidents were 55% in the larnygeal mask airway group vs. 30% in the laryngeal tube group (P < 0.05). Conclusions: The target effect-site concentration of propofol for insertion of laryngeal tube was lower than for larnygeal mask airway (P < 0.05), with a consequent reduction of the propofol induced haemodynamic side-effects.

Summary

Background and objective: Anaesthesia information management systems, though still not used widely, will inevitably replace handwritten records and may eventually serve as a core for the development of computerized decision support. We investigated staff expectations and the accuracy of data entry in a recently implemented commercially available anaesthesia information management system. Methods: A structured questionnaire was administered to the staff before and 1 week and 3 months after implementation in order to assess their opinion. The quality of manual data entry, and of automatic data record was evaluated by looking for missing data and the prevalence of artefacts. Results: Despite initial fears the users quickly accepted the system. Both automatic and manual data entry were found to be accurate and reliable while the prevalence of artefacts was relatively low. Conclusions: A commercially available anaesthesia information management system can be easily implemented and used instead of paper charts.

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.