Patients receiving anticoagulants offer a challenge to anaesthesiologists. The issue of spinal haematoma following central neuraxial block in such patients is a contentious issue. Although rare, with an estimated incidence of <1 : 150 000 for epidural blocks and 1 : 220 000 for spinal anaesthetics in patients with normal coagulation status, this is an emergency situation with a potentially grave prognosis. The review presents cases of spinal haematomata that have occurred in the last 5 years, both spontaneously and after central neuraxial blockade. Of the 60 cases reported in the literature, 33% occurred following central neuraxial block and, of these, 55% were associated with concomitant use of anticoagulants. The pharmacology of the newer and older anticoagulants is also described. The variety of risk factors and diverse recommendations that have been described in these patients are reviewed.

Background and objective: Assessment of the effects of normovolaemic haemodilution on middle cerebral artery blood flow velocity with transcranial Doppler ultrasonography, intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery.

Methods: Normovolaemic haemodilution was induced in rabbits under general anaesthesia, and the haematocrit was allowed to decrease to 30% in Group 1 (n = 6) and to 20% in Group 2 (n = 6). Peak systolic and diastolic velocities, mean blood flow velocity, and pulsatility and resistance indices of the middle cerebral artery were measured by transcranial Doppler ultrasonography. Changes in intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery were also assessed.

Results: In Group 2, middle cerebral artery blood flow velocity increased from 0.4 ± 0.01 to 0.51 ± 0.02 m s−1 after the induction of normovolaemic haemodilution (P = 0.04), while arterial oxygen content decreased from 16.2 ± 0.1 to 8.5 ± 0.1 mL dL−1 (P = 0.002). The decrease in cerebral oxygen delivery from 6.5 ± 0.2 to 4.3 ± 0.2 was also significant (P = 0.02). However, no associated changes in intracranial pressure and cerebral perfusion pressure could be demonstrated.

Conclusions: Normovolaemic haemodilution resulted in an increase in the mean blood flow velocity of the middle cerebral artery. However, this increase did not compensate for the consequences of the altered oxygen delivery to the brain when the haematocrit was reduced to 20%

Background and objective: The arterial thermodilution technique offers the ability to measure cardiac output using only central venous and arterial catheters. However, the technique has been reported to overestimate cardiac output because of a higher loss of cold indicator due to the increased distance between the sites of injection and measurement. In this study, the two techniques were compared with respect to conditions of low cardiac output in which a longer passage time may further increase loss of indicator.

Methods: Seventeen anaesthetized dogs were studied during hypovolaemic shock and fluid resuscitation. Cardiac output measurements were carried out simultaneously by arterial and pulmonary artery thermodilution techniques.

Results: One-hundred-and-two measurements were performed. The mean cardiac output was 2.28 ± 1.4 L min−1 by the pulmonary arterial technique and 2.29 ± 1.56 L min−1 by the arterial thermodilution technique. The correlation coefficient between the two measurements was 0.95, the precision −0.04 ± 0.41 L min−1 and the limits of agreement from −0.86 to 0.78 L min−1. The agreement was also consistent at low cardiac outputs.

Conclusions: The arterial thermodilution technique may serve as a less invasive cardiac output monitor in conditions of severe bleeding and shock.

Background and objective: Some halogenated agents, especially methoxyflurane, because of a higher level of fluoride production, induce a renal concentrating defect that could be related to an ascending limb impairment. We investigated the mechanisms of fluoride toxicity on an immortalized cell line.

Methods: Cells were cultured for 2, 6 or 24 h in the presence of fluoride. Toxicity evaluation was based on: cell numbers, protein content, leucine-incorporation, lactate dehydrogenase (LDH) and N-acetyl-βglucosaminidase (NAG) releases, Na-K-ATPase and Na-K-2Cl activities, electron microscope studies. Infrared analysis and fluoride microdetermination allowed crystal components.

Results: At 5 mmol after 24 h, fluoride decreased cell numbers (−14%, *P < 0.05), protein content (−16%*), leucine incorporation (−54%*), Na-K-2Cl activity (−84%*), increased LDH (+145%*) and NAG release (+190%*). Na-K-ATPase was more sensitive and impaired from 1 mmol for 24 h and after 2 h at 5 mmol. Crystal formation in mitochondria occurred after 6 h at 5 mmol. Infra-red analysis and fluoride microdetermination established that crystals contained sodium, phosphate and fluoride.

Conclusions: The results suggest that the Na-K-ATPase pump is a major target for fluoride toxicity in Henle's loop.

Background and objective: This prospective, randomized, double-blinded study was designed to compare the effects of remifentanil or fentanyl on anaesthetic induction characteristics of propofol, thiopental or etomidate.

Methods: Seventy-two patients were enrolled in six groups of 12 individuals each. In three groups, fentanyl was given as a bolus dose of 1.5 μg kg−1, whereas the others received a remifentanil infusion at 0.5 μg kg−1 min−1. Five minutes later, propofol, thiopental or etomidate were titrated to a state of unresponsiveness. Assessment included the amounts of drug necessary for induction, haemodynamics and the times to apnoea, loss of eyelash reflex, and the release of a water-filled syringe held in the patient's hand.

Results: Induction times to loss of the eyelash reflex were significantly shorter in the remifentanil than in the fentanyl groups: with propofol 50.7 ± 13.6 s (mean ± SD) versus 74.9 ± 27.0 s (P < 0.01), with thiopental 42.9 ± 16.8 s versus 77.2 ± 27.8 s (P < 0.01) and with etomidate 54.7 ± 17.6 s versus 72.3 ± 24.0 s (P < 0.05). The times to respiratory arrest or for the syringe to fall were significantly shorter with remifentanil than with fentanyl for propofol and for thiopental, but not for etomidate. In terms of dosages per kg body weight necessary to achieve unresponsiveness, less propofol (−29%, P < 0.05), thiopental (−25%, P < 0.05) or etomidate (−32%, P < 0.01) was necessary with remifentanil than with fentanyl. Haemodynamic responses to tracheal intubation were controlled more effectively with remifentanil. However, within the remifentanil groups, mean arterial pressure significantly decreased during induction: −26% with propofol,−18% with thiopental and −14% with etomidate (all P < 0.01).

Conclusions: During anaesthetic induction, a remifentanil infusion of 0.5 μg kg−1 min−1 over 5 min is a suitable alternative to a 1.5 μg kg−1 bolus dose of fentanyl: induction times are shorter with reduced amounts of propofol, thiopental or etomidate.

Background and objective: We measured the physical performance error of commercial syringe pumps incorporating the Diprifusor® module to deliver propofol by target-controlled infusion in a laboratory experiment.

Methods: Three infusion devices (Graseby 3500®; Fresenius Vial Master TCI®; Alaris TIVA-TCI®) were studied when infusing propofol at six different target concentrations (1, 1.5, 2, 3, 5, 8 µg mL−1) over 10 min. This procedure was repeated five times to average each target. Precision measurements were based on the volume delivered and a mean performance error was calculated.

Results: The mean performance error bandwidth for all pumps was from −2.07 to 4.22% with a 95% confidence interval always <4.5%. There was a higher variability at lower target concentrations associated with lower infusion rates. The Alaris TIVA-TCI® pump showed the largest overall bias whereas the Fresenius Vial Master TCI® pump had the smallest divergence and the lowest variation across all target concentrations. The Graseby 3500® pump had the smallest range in mean performance error with an acceptable variation (95% CI <2%).

Conclusions: Despite the differences between the pumps, which may be related to the synchronization of the hardware components, the absolute inaccuracies in the physical performance were low and presumably negligible from a clinical point of view.

Background and objective: The study aimed to evaluate and improve airway management in the prehospital setting, i.e. physicians working on board ambulances. A quality control programme focusing on anaesthesia was instituted to improve the time taken to perform endotracheal intubation.

Methods: All consecutive patients requiring tracheal intubation were prospectively analysed before (first period) and after the training programme focusing on anaesthetic protocols for tracheal intubation (second period). The number of attempts at laryngoscopy, the time taken to achieve tracheal intubation, the difficulties encountered and the related complications of the anaesthetic technique were recorded. At the end of the first period, the results were reported to the whole staff of the unit and the anaesthesia protocols were then modified by introducing succinylcholine into the induction sequence, as part of a training programme.

Results: Two-hundred-and-eighty patients were evaluated (97 in the first period, 183 in the second). All patients were successfully intubated in both periods. The percentage of difficult intubations (as assessed by the physician) was lower in the second period (20 versus 35%, respectively; P < 0.01). The success rate at the first attempt was significantly higher (74% [68–80] 95% CI versus 55% [45–65] 95% CI, P < 0.01) and the duration of intubation was significantly shorter in the second period than in the first (1.4 ± 3.2 vs. 4.1 ± 6.7 min, respectively; P < 0.001). The incidence of complications (hypoxaemia, laryngospasm, bronchospasm) was lower in the second period (15 versus 31%, P < 0.01).

Conclusions: The time to perform tracheal intubation can be improved by the introduction of succinylcholine into the prehospital anaesthetic protocol. Rapid sequence induction should be taught as a way of improving tracheal intubation in the prehospital setting.

Background and objective: Comparison of the effectiveness of tramadol with meperidine given intravenously to emergency patients with suspected renal colic.

Methods: A double-blind, randomized clinical trial was performed in the Emergency Department of a tertiary-care university hospital. Consecutive patients with suspected renal colic (n =47) were randomized to receive intravenously an initial dose of tramadol 50 mg (n = 23) or meperidine 50 mg (n = 24). After 30 min, additional doses of meperidine 50 mg were given intravenously as a rescue medication in an open fashion. Pain relief was assessed using a 10 cm visual analogue scale, the primary outcomes being pain relief at 15 and 30 min after the analgesics. Secondary outcomes were the frequency of rescue meperidine use and the development of side-effects.

Results: Visual analogue scale pain scores after 15 and 30 min decreased in both tramadol and meperidine groups (P < 0.05). However, pain relief was better in the meperidine group at the 15 and 30 min evaluations (P < 0.05). Only 11 patients (48%), initially receiving meperidine, needed more meperidine compared with 16 patients (67%) initially receiving tramadol. Both drugs were well tolerated with no adverse effects occurring in either group.

Conclusions: Meperidine 50 mg was superior to tramadol 50 mg for acute pain relief in patients with suspected renal colic when given intravenously. Because many patients in both groups received supplemental meperidine and the response to tramadol alone cannot be predicted, clinicians may want to choose higher doses of meperidine alone or other alternative combinations.

Background and objective: To compare the conditions for insertion of the laryngeal mask airway using sevoflurane or propofol plus fentanyl. We evaluated the haemodynamic changes and cost of induction of anaesthesia in both groups.

Methods: Sixty patients were equally and randomly divided into two groups. Both groups received fentanyl 1 μg kg−1. Patients in the sevoflurane group were induced with 8% sevoflurane and those in the propofol group with propofol 2.5 mg kg−1. Conditions for insertion were graded on a three-point scale using six variables. Overall, conditions were assessed as excellent, satisfactory or poor based on the total score in each group. Systolic and diastolic arterial pressure and heart rate were recorded for 6 min after mask insertion. The financial cost of induction in both groups was calculated.

Results: The mean (±SD) time taken from induction to successful laryngeal mask insertion was significantly shorter with propofol (68.70 ± 22.60 s) compared with sevoflurane (149.83 ± 55.25 s). Excellent or satisfactory conditions were observed in 30 (100%) patients in the propofol group and in 29 (96.66%) in the sevoflurane group. Systolic and diastolic arterial pressures were significantly lower in the propofol group. The cost of sevoflurane used was €3.95 ± 1.48 (Rs 216.23 ± 64.66) (P < 0.05) compared with that of propofol, which was €3.23 ± 0.65 (Rs 141.00 ± 28.20).

Conclusions: Although there was a faster induction with propofol-fentanyl, conditions for insertion of the laryngeal mask airway were similar in both groups. Haemodynamic stability was better with sevoflurane-fentanyl. The propofol-fentanyl combination was more cost-effective.

Stellate ganglion block is a selective sympathetic block that affects the ipsilateral head, neck, upper extremity and upper part of the thorax. Convulsions are a recognized complication of intra-arterial injection during stellate ganglion block. As central nervous system toxicity depends ultimately on the concentration of the local anaesthetics presented to the brain, the likely causative factors are discussed as well as the types of toxic symptoms and their onset times. The paper considers the aetiological factors of such convulsions resulting from stellate ganglion block in two patients.