Summary

Background and objective: Thiopental has been reported to reduce sympathetic tone, however, it is not clear whether change in heart rate variability is associated with depth of anaesthesia. The purpose of the present study was to evaluate changes in heart rate variability at different depths of hypnosis during induction of anaesthesia with thiopental. Methods: We studied 17 ASA I patients scheduled for minor surgery. The depth of hypnosis was monitored by the BIS. Spectral analysis of heart rate variability using a maximum entropy method resulted in a characteristic power spectrum with two main regions, a high frequency and a low frequency. Haemodynamics, entropy, low frequency, high frequency and low frequency/high frequency were monitored in an awake state and after the induction of anaesthesia. Results: Heart rate increased in a BIS-dependent manner, whereas blood pressure showed no significant changes during the study period. High frequency, entropy and low frequency decreased with a reduction in the BIS value. Low frequency/high frequency showed no significant change during the study period. Conclusions: Induction of anaesthesia with thiopental increased heart rate and decreased high frequency, entropy and low frequency in a BIS-dependent manner, indicating that thiopental reduces cardiac parasympathetic tone depending on the depth of hypnosis.

Background and aim This study assessed the accuracy of using capnography with a modified, hollow gum elastic bougie in predicting tracheal intubation, and its effectiveness as a method of apnoeic oxygenation.

Methods Patients were randomly allocated to having the gum elastic bougie inserted, under anaesthesia, in the trachea or the oesophagus. End-tidal carbon dioxide measurements were made at 10 and 20 s. The position of the gum elastic bougie was correctly predicted in 89.2% of patients. We tested the apnoeic oxygenation on an anaes-hetic simulator model, which is housed in the Scottish Anaesthesia Simulator Centre, Stirling, UK.

Results The time taken for the oxygen saturation to fall to 90% was significantly prolonged when the gum elastic bougie was used for apnoeic oxygenation.

Conclusion The modification of the gum elastic bougie allows a more objective assessment of correct placement than the previous tactile method. The current design of bougie is unsuitable but can be modified.

We describe a case of paradoxical air embolism during orthotopic liver transplantation, early diagnosis, using intra-operative transoesophageal echocardiography after a circulatory failure, allowed early management by hyperbaric oxygen therapy.

Summary

The history of intrathecal and epidural anaesthesia is in parallel with the development of general anaesthesia. As ether anaesthesia (1846) is considered the first modern anaesthetic since its use by Morton 157 yr ago, so Bier made history by using cocaine for intrathecal anaesthesia in 1898. The first published report on opioids for intrathecal anaesthesia belongs to a Romanian surgeon, Racoviceanu-Pitesti, who presented his experience at Paris in 1901. It was almost a century before the opioids were used for epidural analgesia. Behar and his colleagues published the first report on the epidural use of morphine for the treatment of pain in The Lancet in 1979. Epidural and intrathecal opioids are today part of a routine regimen for intra- and postoperative analgesia. Over the last 30 yr, the use of epidural opioids has became a standard for analgesia in labour and delivery, and for the management of chronic pain. Finally, epidural opioids have been shown to have a pre-emptive effect, when used before major surgery. We present the evolution of neuraxial anaesthesia and the history of intrathecal and epidural administration of opioids.

We studied the direct effect of intravenous anaesthetics, local anaesthetics and premedication drugs in common use for major surgery, on the spontaneous versus lectin induced proliferation of cultured normal rat peripheral blood mononuclear cells, not exposed to surgical or any other trauma prior to culture. Peripheral blood mononuclear cells were incubated in cell-culture medium in the presence or in the absence of propofol, ketamine, fentanyl, midazolam, thiopental sodium, lidocaine or etomidate. The cells proliferated either spontaneously or under stimulation with a lectin phytohaemagglutinine P for 72 h. The proliferation rate was evaluated by 2H-Thymidine incorporation. Fentanyl, thiopental sodium, lidocaine and etomidate significantly inhibited phytohaemagglutinine P induced 3H-Thymidine incorporation in cultured rat peripheral blood mononuclear cells. Counts per minute of the cultures treated with these drugs were 1667.80±745.72, 1614.1±615.00, 1688.0±615.0 and 1549±560.41, respectively, compared with the phytohaemagglutinine P stimulated positive control counts per minute, 13488±4305.6 (P<0.001 in each comparison). Propofol, ketamine and midazolam inhibited the lectin-induced cell proliferation to levels not statistically different from the baseline. Counts per minute of these cultures were 1361.90±745.73; 1108.90±751.33 and 1518.10±848.88, respectively. Compared either with the baseline 972.57±356.73 counts per minute or to the positive control culture counts per minute, 13488±4305.6 the difference was statistically significant (P<0.001) in each comparison. All the substances tested in this study proved capable of exerting direct inhibitory effect on circulating immunocompetent cells, because the latter were not subjected to any other immunosuppressive factor, be it operative trauma, blood transfusion, malnutrition, drug abuse, prior to culture. The possible theoretical and practical implications are discussed in this study.

Summary

Background and objective: Although an epidural autologous blood patch is considered the most effective treatment for post dural puncture headache, which sometimes occurs following spinal or inadvertent spinal anaesthesia, there remains a need for alternative materials for epidural patches. We investigated the potential neurotoxicity of Dextran 40 (Rheomacrodex) and Polygeline (Haemaccel) used for this purpose in a rat model. Methods: Repeated boluses of 10% Dextran 40, 3.5% Polygeline or 0.9% saline were injected intrathecally over a period of 1 month in three groups of rats. Results: No behavioural or clinical derangements were observed in any of the three groups during this period. After sacrifice of the animals at the end of the experiment, no significant differences in the histopathological appearances of the spinal cords in the three groups were observed. No toxic effects diminishing viability of spinal cord cells were evident. Similarly, viability of renal, hepatic and peripheral blood mononuclear cells remained unaffected (98% ± 2%). Conclusions: No deleterious effects, clinical or cellular, were evident in this rat model when Dextran 40 or Polygeline were injected intrathecally. Thus, both substances can be considered as possible alternative materials for epidural patches.

Background and objective: The effects of altering the concentration of a local anaesthetic on the development of epidural anaesthesia in pregnant females are unclear. We compared the anaesthetic effects of a constant dose of two different concentrations of epidural lidocaine for Caesarean section.

Methods: After Institutional Review Board approval and informed consent, patients undergoing elective Caesarean section were randomized to receive either lidocaine 1% 30 mL (+epinephrine 5 μg mL−1) or lidocaine 2% 15 mL (+epinephrine 5 μg mL−1) (n = 20 each) for epidural anaesthesia at the L1-L2 interspace. The spread of the sensory block to pinprick and the degree of motor block (modified Bromage scale) were measured at 5, 10, 15, 20 and 30 min after injection.

Results: No significant differences in the progression of analgesia and motor block were observed at any time between 1 and 2% lidocaine. The maximum cephalad spread was observed 30 min after injection; the median was at T4 (range T3–T5) and at T4 (range T3–T6) for lidocaine 1 and 2%, respectively.

Conclusions: The same doses but different volumes of lidocaine 1 and 2% produced comparable anaesthetic effects in pregnant females. The effects of epidural anaesthesia depend primarily on the total dose of the local anaesthetic.

Summary

Background and objective: Different types of polymer surfaces affect the activation of platelets and coagulation pathway containers depending on their surface qualities. Importantly, this could produce variability of coagulation results obtained with thrombelastographical analysis. We assessed the effects of blood storage on thrombelastograph, TEG®, variables using polypropylene and polycarbonate containers. Methods: An in vitro experiment was performed, with eight volunteers in each limb. Fresh whole blood was stored in polypropylene or polycarbonate tubes prior to TEG® analysis, to assess the role of these plastics in the TEG® results obtained. Results: The polycarbonate tubes displayed slower onset of coagulation and greater variability of data for all four basic TEG variables (r-time, k-time, α-angle and maximum amplitude, P < 0.05). Polycarbonate results fell outside manufacturer reference ranges. Conclusions: It is likely that this is due to the altered surface properties and charge effects of the containers affecting proteins and platelets differently. Caution should be used in choosing which containers are used for storage of fresh blood prior to coagulation assessment, as variable results will follow where different types of plastic containers are employed.

Summary

Background and objective: Surgical treatment of patients presenting with subarachnoid haemorrhage secondary to a leaking cerebrovascular aneurysm involves coiling or clipping. Traditionally all patients undergoing this procedure are cross-matched routinely. With ever-increasing strains on the health budget and transfusion services in particular, as well as the real, albeit low risk of transfusion transmitted disease, we propose that a simple ‘group and save’, coupled with a reliable ‘fast-issue’ blood transfusion service should replace this outdated concept. Method: To assess this assumption, we carried out a retrospective analysis of 103 patients who underwent clipping or coiling during January to December 2001 in our Neurosurgical Unit. Results: All patients but one had been cross-matched (99%). However, only 33 patients (32%) eventually required a blood transfusion. In real terms, this meant a total of 294 units of blood that had been cross-matched routinely, in our series of 103 patients, were not used. Had these patients only been ‘group and saved’ and a system of ‘fast-issue’ been adopted, assuming that none of the patients had abnormal antibodies, the blood transfusion department would have made a saving of £4815.72 for this group of patients. Conclusion: We conclude that advances in surgical technique have made routine cross-matching of blood in cerebral aneurysm surgery unnecessary.

It is assumed that diabetic patients with uraemia have more complications at renal transplantation than those who are not diabetic. We compared the preoperative ECGs, and invasive perioperative haemodynamic and oxygenation parameters in 15 diabetic and 15 non-diabetic uraemic patients undergoing renal transplantation. The number of patients with increased QT dispersion in the ECG was higher in diabetic than in non-diabetic patients (P < 0.05). Before anaesthesia, heart rate and mean arterial pressure were higher (P <0.05) in the diabetic than in the non-diabetic group. After preanaesthetic volume loading all patients showed a hyperdynamic circulation, which subsided during anaesthesia. However, stroke volume index remained unchanged. Four patients in the diabetic group and six in the non-diabetic group needed additional oxygen therapy after surgery. No cardiac dysrhythmias were noted. However, the increased QT dispersion in diabetic patients calls for an adequate perioperative ECG monitoring for dysrhythmias. The diabetic and non-diabetic uraemic patients performed equally well at renal transplantation. In conclusion, renal transplantation for diabetics is justified.