Summary

Background and objective: No clinical trials comparing the characteristics of sensory blockade caused by various local anaesthetics in thoracic paravertebral blockade have been published. The aim of this prospective study was a clinical assessment of sensory blockade after paravertebral injection of ropivacaine or bupivacaine in patients undergoing modified radical mastectomy. Methods: Seventy ASA I–II patients were randomized to receive a single injection of ropivacaine 0.5% (n = 35) or bupivacaine 0.5% (n = 35) at the T4 level. General anaesthesia with propofol and fentanyl was provided during the procedure and patients were not intubated. The following parameters were analysed: duration and dynamics of the sensory blockade and the patient's and surgeon's assessment. Results: Both ropivacaine and bupivacaine provided a similar level of analgesia. Ropivacaine was characterized by more rapid onset – after only 5 min 53% of patients in this group had the extent of sensory blockade wide enough to perform modified radical mastectomy in comparison to only 20% after bupivacaine (P < 0.01). The initial spread of sensory blockade (>9 segments blocked) was noted more often in the ropivacaine group (88% vs. 65%, P < 0.05), lasted longer and appeared to be wider than sensory blockade produced by bupivacaine. Regression of sensory blockade was initially similar, but after 24 h sensory blockade in the ropivacaine group still had a potential to provide analgesia for modified radical mastectomy in 81% of patients in comparison to only 50% of such patients in the bupivacaine group (P < 0.05). Degree of postoperative pain, performance of the cardiovascular system, consumption of medications and complications were all similar between the study groups. Conclusions: Both agents provide satisfactory conditions for mastectomy, but ropivacaine seems to be superior to bupivacaine for thoracic paravertebral blockade during breast cancer surgery.

Summary

Background and objective: Adenosine, by intravenous and intrathecal routes, is known to alleviate various types of pain. However, the role of intrathecal adenosine in providing postoperative analgesia has not been confirmed. The aim of the present study was to evaluate the efficacy of intrathecal adenosine for postoperative pain relief, and to determine its role for pre-emptive analgesia. Methods: Ninety ASA I and II females, undergoing elective abdominal hysterectomy, were randomly divided into three groups of 30 patients each. Patients in the ‘early adenosine’ group received intrathecal adenosine 1000 μg, 30 min before induction of anaesthesia. Patients in the ‘late adenosine’ group received the same dose before reversal of neuromuscular blockade. Control patients did not receive any test drug. A balanced general anaesthesia technique was used in all patients. Pain intensity scores using a visual analogue scale, sedation scores, time to first rescue analgesic and total morphine requirement were recorded. Results: There was no significant difference in pain intensity scores, sedation scores, total morphine requirements and time to first rescue analgesic among the three groups. Conclusion: Intrathecal adenosine 1000 μg is not effective as an analgesic for postoperative pain relief, and there is no pre-emptive effect.

Summary

Background and objective: The best place for the electrode of transcutaneous measurement of oxygen tension (tcPO2) and carbon dioxide tension (tcPCO2) during general anaesthesia was investigated in three different locations. Methods: Fifteen patients for major abdominal surgery in the supine position were studied. The electrode of the TCM4™ (Radiometer, Copenhagen, Denmark) was put on the chest, upper arm or forearm. TcPO2, tcPCO2, end-tidal carbon dioxide tension (etCO2), percutaneous oxygen saturation (SaO2), arterial oxygen tension (PaO2 ) and arterial carbon dioxide tension (PaCO2) were simultaneously measured at four different etCO2 concentrations and inhaled oxygen percentages and the location of the electrode was changed to other places to repeat the same measurement. In total, 12 measurements for each patient and 60 measurements for each place were performed. Results: TcPO2 correlated better than SaO2 (R2 = 0.58) with PaO2 (R2 = 0.76), and tcPCO2 correlated well with PaCO2 (R2 = 0.76) and etCO2 (R2 = 0.74) when the electrode was put on the chest, while not on the upper arm or forearm (R2 < 0.5). However, limits of agreement were too big to use tcPO2 (bias, −67.9; limits of agreement, 16.5, −152.3) and tcPCO2 (bias, −0.47; limits of agreement, 8.7, −9.64) as surrogate measures of PaO2 and PaCO2, respectively even when the electrode was put on the chest. Conclusions: When the electrode was put on the chest, tcPO2 and tcPCO2 might be available as non-invasive monitors of oxygenation and CO2 status during general anaesthesia, while the absolute values were not interchangeable with PaO2 and PaCO2, respectively.

Major knee surgery is associated with moderate or severe post-operative pain. Intrathecal morphine and continuous femoral 3-in-1 block were compared prospectively in 40 patients for pain after major knee surgery under spinal anaesthesia, with 4 mL isobaric 0.5% bupivacaine. In a random order, 20 patients received preservative free morphine 0.3 mg mixed with spinal bupivacaine. In 20 patients, following spinal anaesthesia with only bupivacaine, femoral 3-in-1 block was performed post-operatively with 0.5% bupivacaine 2 mg kg−1. The block was continued via a catheter with 0.25% bupivacaine 0.1 mL h−1 kg−1 until the next morning (24 h after induction of spinal anaesthesia). Intramuscular oxycodone was given as a rescue analgesic in all patients. Two patients from the femoral group were excluded due to technical failure. Three patients in the morphine group and one patient in the femoral group did not need any additional oxycodone. In the morphine group on average 2.8 (range 0–7) and in the femoral group 3.2 (0–5) additional doses of oxycodone were needed during the 24 h observation period. The mean pain scores were significantly lower in the morphine group at 9 and 12 h into the 24-h trial. Itching was seen only in the morphine group (40% of the patients). Other side effects were similar in the two groups. All patients were satisfied with their pain therapy. Both intrathecal morphine and femoral 3-in-1 block alone were insufficient for the treatment of severe pain after major knee surgery.

Summary

Background and objective: Acute renal failure is a serious complication of cardiac surgery. We studied the long-term survival and quality of life of patients requiring renal replacement therapy after cardiac surgery, since they represent a heavy burden on hospital resources and their outcome has never been adequately evaluated. Methods: Out of 7846 consecutive cardiac surgical patients, 126 (1.6%) required postoperative renal replacement therapy: their preoperative status and hospital course was compared with patients who had no need of postoperative renal replacement therapy. A multivariate analysis identified predictors of renal replacement therapy. Long-term survival and quality of life was collected in patients who had renal replacement therapy and in case-matched controls. Results: Hospital mortality in the study group was 84/126 (66.7%) vs. 118/7720 (1.5%) in the control population (P < 0.001). Patients who underwent renal replacement therapy and were discharged from the hospital (42 patients) had a reasonable long-term outcome: at 42 ± 23 months, 30 out of 42 patients were alive, with only 3 patients complaining of limitations in daily activities. Predictors of in-hospital renal replacement therapy were: emergency surgery, preoperative renal impairment, intra-aortic balloon pumping, reoperation for bleeding, previous cardiac surgery, female gender, low ejection fraction, bleeding >1000 mL, chronic obstructive pulmonary disease and age. Conclusions: This study confirms that the in-hospital mortality of patients requiring renal replacement therapy is high and shows a low long-term mortality with reasonable quality of life in patients discharged from hospital alive.

Summary

Background and objective: The present study was designed to compare cerebral oxygenation measured with near infrared spectroscopy and local brain tissue oxygen partial pressure, respectively, in pigs during cardiopulmonary resuscitation. Since tissue overlying the brain may have an impact on near infrared spectroscopy readings, we tested whether optode placement on intact skin or on the skull yielded comparable results. Methods: Twelve healthy pigs were anaesthetized and subjected to continuous haemodynamic, near infrared spectroscopy and brain tissue oxygen partial pressure monitoring. After 4 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was started and arginine vasopressin was administered repeatedly three times. Near infrared spectroscopy values recorded were both the tissue oxygenation index and the tissue haemoglobin index as well as relative changes of chromophores (haemoglobin and cytochrome oxidase). Four animals served as control and were measured with both near infrared spectroscopy optodes mounted on the intact skin of the forehead, while in the remaining eight animals, one near infrared spectroscopy optode was implanted directly on the skull. Results: Near infrared spectroscopy readings at the skin or at the skull differed consistently throughout the study period. After arginine vasopressin administration, near infrared spectroscopy values at the different locations showed a transient dissociation. In contrast to near infrared spectroscopy measured on intact skin, near infrared spectroscopy readings obtained from skull showed a significant correlation to brain tissue oxygen partial pressure values (r = 0.67, P < 0.001). Conclusion: Near infrared spectroscopy readings obtained from skin and skull differed largely after vasopressor administration. Near infrared spectroscopy optode placement therefore may have an important influence on the tissue region investigated.

Background and aim The effects of analgesic drugs on sleep are poorly understood. We investigated short- and medium-term effects of tramadol on sleep structure.

Methods Eight healthy volunteers received a placebo (predrug placebo-night), then, in a randomized, double-blind, cross-over fashion a single oral dose of tramadol 50 mg or 100mg (drug-night), and finally, again a placebo (postdrug placebo-night). Standardized polysomnography (electroencephalogram, electro-oculogram, submental electromyogram) was continuously recorded during placebo- and drug-nights

Results During drug-nights both doses of tramadol significantly increased the duration of stage 2 sleep, and significantly decreased the duration of slow-wave sleep (stage 4). Tramadol 100mg but not 50 mg significantly decreased the duration of paradoxical (rapid eye movement) sleep. In the placebo-night after tramadol 100mg (but not after 50 mg) duration of stage 2 sleep was significantly shorter, and duration of stage 4 sleep was significantly longer compared with the predrug placebo-night. Conclusion In healthy volunteers, a single dose of tramadol 50 mg disturbs sleep in the night of drug application. With 100mg, sleep is disturbed in both the night of drug application and in the subsequent night.

Summary

Background and objective: Anaesthesiologists need parameters that measure the depth of anaesthesia. In the context of this need, the present study investigated in rats how two variables from the electroencephalogram, the burst suppression ratio and effective correlation dimension correlated with a measure of anaesthetic depth as measured in the strength of a noxious withdrawal reflex. Methods: Eight rats were exposed to different inspiratory concentrations of sevoflurane, each rat in two separate experiments. In the first experiment, spontaneously breathing animals could move freely and no painful stimuli were applied. In the second experiment, in mechanically ventilated restrained anaesthetized rats, the withdrawal reflex was measured every 80 s. In both experiments the electroencephalogram was continuously recorded. The concentration in the effector compartment was estimated using a first order two compartment model. Correlation dimension was computed following the Grassberger/Procaccia/Takens approach with optimized parameter settings to achieve maximum sensitivity to anaesthetic drug effects and enable real-time computation. The Hill, equation was fitted to the data, describing the effect as a function of sevoflurane concentration. Results: Good correlations of Depth of Anaesthesia with correlation dimension as well as burst suppression ratio were established in both types of experiments. Arousal by noxious stimuli decreased burst suppression ratio and increased correlation dimension. The effective sevoflurane concentration associated with 50% of the maximum effect (C50) was higher in experiment II (stimulation) than in experiment I (no stimulation): i.e. for correlation dimension 2.18% vs. 0.60% and for burst suppression ratio 3.07% vs. 1.73%. The slope factors were: γCD = 4.15 vs. γCD = 1.73 and γBSR = 5.2 vs. γBSR = 5.4. Correlation dimension and burst suppression ratio both correlated with the strength of the withdrawal reflex with correlation coefficients of 0.46 and 0.66 respectively (P < 0.001). Conclusions: Both correlation dimension and burst suppression ratio are related to anaesthetic depth and are affected by noxious stimuli. The relationship between anaesthetic depth and burst suppression ratio is confirmed and the potential of correlation dimension is demonstrated.

Dopamine decreases gastric tone and may therefore influence gastrointestinal motility. The aim of this investigation was to study the effects of a continuous infusion of dopamine on gastric emptying and orocaecal transit time. Nine healthy male volunteers were studied on two occasions in a randomized order. All volunteers received on separate days a continuous infusion of dopamine 5 μg kg−1 min−1 on one occasion and normal saline on the other occasion. Gastric emptying was measured by the paracetamol absorption test and orocaecal transit time by the hydrogen breath test. During the dopamine infusion the area under the paracetamol concentration curve was significantly smaller than during control conditions (P=0.02). Orocaecal transit time was prolonged during the dopamine infusion (P=0.02). Dopamine delays gastric emptying and prolongs orocaecal transit time.

Summary

Background and objective: We tested the feasibility of using the intubating laryngeal mask airway Fastrach™ (ILMA) as a ventilatory device and for flexible lightwand-guided tracheal intubation for out-of-hospital cardiopulmonary resuscitation by an emergency physician. Methods: After completion of a training programme, a single experienced emergency physician used the technique for all patients requiring out-of-hospital tracheal intubation over a 10-month period. If access to the head and neck was limited, the intubating laryngeal mask airway was inserted from below and to the side, otherwise it was inserted from above the head. Data about the time for the ambulance to reach the patient, whether or not access to the head and neck was limited, whether or not circulation was successfully restored, and the insertion and intubation success rates were noted. Results: The mean (range) time for the ambulance to reach the patient was 12 (10–20) min. Access to the head and neck was limited in 8/37 (22%). Circulation was successfully restored in 10/37 (27%). The intubating laryngeal mask airway was successfully inserted at the first attempt in 35/37 (95%) and at the second attempt in 2/37 (5%). The tracheal tube was successfully inserted in 25/37 (67.5%) at the first attempt, 7/37 (19%) at the second attempt and 5/37 (13.5%) at the third attempt. There were no overall failures for intubating laryngeal mask airway insertion or tracheal intubation. There were no differences in success rate between positions. Oesophageal intubation was detected and corrected in 2/37 (5%). Conclusion: The intubating laryngeal mask airway has a high success rate as a ventilatory device and as a flexible lightwand-guided airway intubator during out-of-hospital cardiopulmonary resuscitation by a well-trained emergency physician. This technique may be particularly useful when there is limited access to the head and neck.

Summary

Background and aim: The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg−1 under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg−1 rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients. Methods: With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg−1 was given intravenously after induction of anaesthesia with propofol 1–2 mg kg−1 and fentanyl 2 μg kg−1. Propofol 6–12 mg kg−1 h−1 was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant. Results: No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block. Conclusions: Rocuronium 0.3 mg kg−1 is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.

Raised intracranial pressure and low cerebral perfusion pressure are associated with ischaemia and poor outcome after brain injury. Therefore, many management protocols target these variables. However, there are no randomized controlled trials that have demonstrated the effectiveness of intracranial pressure-guided care in severely head-injured patients. Observational studies of such therapy have yielded inconsistent results, ranging from decreased mortality to no effect or increased morbidity or mortality. A recent cohort study supports the notion that the possible benefits of intracranial pressure monitoring after traumatic brain injury are small – if present – and would exceed a number needed for the treatment of 16. Furthermore, intracranial pressure monitoring and aggressive management of intracranial pressure and cerebral perfusion pressure have been associated with increased lengths of stay in the neurocritical care unit, conceivable costs and possibly an increased rate of complications. Against this background, there is sufficient clinical equipoise to warrant an adequately powered randomized controlled trial to compare intracranial pressure-guided care with supportive critical care without intracranial pressure monitoring in patients with severe traumatic brain injury. However, the realization of such a trial is likely to be problematic for a number of reasons, not least of which the firmly held biases of many clinicians.

The present report describes a case of cardiac arrest and subsequent death as a result of hyperkalaemia following the use of suxamethonium in a 23-year-old Malawian woman. Five days after the onset of the symptoms of meningitis, the patient aspirated stomach contents and needed endotracheal intubation. Forty seconds after injection of suxamethonium, bradycardia and cardiac arrest occurred. Attempts to resuscitate the patient were not successful. The serum level of potassium was observed to be 8.4 mequiv L−1. Apart from the reduction in the patient's level of consciousness, there were no signs of motor neurone damage or of any of the other known predisposing conditions for hyperkalaemia following the administration of suxamethonium. It is postulated that her death was caused by hypersensitivity to suxamethonium, associated with her 5-day immobilization.

The most informative neurophysiological techniques available in the neurosurgical intensive care unit are electroencephalograph and somatosensory evoked potentials. Such tools, which give an evaluation of cerebral function in comatose patients, support clinical evaluation and are complementary to neuroimaging. They serve both diagnostic/prognostic and monitoring purposes. While for the former, discontinuous monitoring is sufficient, for the latter, to obtain increased clinical impact, continuous monitoring is necessary. To perform and interpret these examinations in the neurosurgical intensive care unit, both the technician and the neurophysiologist need specific training in the intensive care field. There is sufficient evidence to show that somatosensory evoked potentials are the best single indicator of early prognosis in traumatic and hypoxic-ischaemic coma compared to the Glasgow Coma Score, computed tomography scan and electroencephalograph. Indeed, somatosensory evoked potentials should always be combined with clinical examination to determine the prognosis of coma. Despite widespread use of somatosensory evoked potentials and their prognostic utility in acute brain injury, few studies exist on continuous somatosensory evoked potential monitoring in the intensive care unit. We carried out a pilot study of continuous electroencephalograph-somatosensory evoked potential monitoring in the neurosurgical intensive care unit (traumatic brain injury and intracranial haemorrhage, Glasgow Coma Score <9, intracranial pressure monitoring). All patients stable from a clinical and computed tomography scan point of view showed no significant somatosensory evoked potential modifications, while in the case of clinical deterioration (23%), somatosensory evoked potentials always showed significant modifications. While somatosensory evoked potentials correlated with short-term outcome, intracranial pressure showed a poor correlation. We believe neurophysiological monitoring is an ideal complement to the other parameters monitored in the neurosurgical intensive care unit. Whereas intracranial pressure is simply a pressure index, electroencephalograph-somatosensory evoked potential monitoring reflects to what extent cerebral parenchyma still remains metabolically active during acute brain injury.

Tramadol, a weak opioid μ-receptor agonist, may have a favourable potency and side effect profile for intravenous patient-controlled analgesia (PCA). In a prospective, double-blind, randomized study involving 54 patients, tramadol was compared with oxycodone in PCA after maxillofacial surgery. All the patients were given diclofenac sodium 1 mg kg−1 intramuscularly and dexamethasone 8 mg twice a day. Post-operatively patients received tramadol or oxycodone by a PCA apparatus (lockout 5 min, tramadol 0.3 mg kg−1 bolus, oxycodone 0.03 mg kg−1 bolus). During the immediate recovery period, opioid was administered i.v. in a double-blind fashion, either tramadol 10 mg or oxycodone 1 mg increments until the pain control was judged to be satisfactory by the patient. Pain was assessed at rest and during activity (mouth opening) before and after loading, at 2 h after commencing the PCA, as well as at 21.00 and at 09.00 hours on the following morning. Side effects were recorded. The potency ratio of tramadol to oxycodone was found to be approximately 8:1. There was no significant difference between the groups in the VAS scores for pain. No respiratory depression was identified. Tramadol was found to provide adequate analgesia after maxillofacial surgery without risk of respiratory depression. However, the incidence of nausea was slightly greater in the tramadol group than in the oxycodone group (44% vs. 28%, NS).

Summary

Background and objectives: The aim of this prospective, randomized, controlled clinical study was to evaluate the effects of thoracic epidural anaesthesia combined with isoflurane/nitrous oxide anaesthesia on intraoperative oxygenation during one-lung ventilation for lung resections.

Methods: Forty patients were randomly allocated to receive general anaesthesia maintained with isoflurane/nitrous oxide (group General, n = 20) or the same anaesthetic combined with thoracic epidural anaesthesia (group Integrated, n = 20). All patients were mechanically ventilated with the same settings (FiO2 = 0.5; VT = 9 mL kg−1; inspiratory : expiratory time = 1 : 1; inspiratory pause = 10%). Effects on oxygenation were evaluated by determining the changes in PaO2/FiO2 ratio at 10, 30, 45 and 60 min of one-lung ventilation as compared to values obtained after induction of anaesthesia (supine, two-lung ventilation).

Results: The PaO2/FiO2 ratio was decreased in both groups during one-lung ventilation until the end of surgery. No differences were found at any observation time between the groups. Ventilation with 100% oxygen because of SPO2 decrease <92% was required in nine patients of group General (45%) and in eight patients of group Integrated (40%) (P = 0.64). Manual re-inflation of the operated lung was required in one patient of group General only (P = 0.99). Heart rate was lower in group Integrated than in group General throughout the study. No differences between the two groups in mean arterial pressure were observed.

Conclusions: Adding a thoracic epidural block to isoflurane/nitrous oxide anaesthesia during one-lung ventilation for lung resections does not result in clinically relevant detrimental effects on intraoperative oxygenation.