Profound and complex coagulation disorders are encountered during liver transplantation. They include preoperative coagulation disorders related to the liver disease and haemostatic changes related to the procedure itself. They commonly lead to increased intraoperative bleeding, especially due to increased fibrinolysis, the contribution of which can be demonstrated by the relative efficacy of antifibri-nolytics. Given the multifactorial nature of bleeding in liver transplantation, preoperative coagulation tests cannot predict blood loss even if some statistical relationship is occasionally found.Preoperative correction of coagulation defects has not been shown to be effective in reducing intraoperative bleeding. Throughout the procedure, a rapid and sensitive method for monitoring coagulation is necessary in order to guide the rational use of blood components and pharmacological agents. The usefulness of such a method to assist management of blood loss or blood component requirements is poorly documented and controversial.

Background and objective In recent studies, ultrasonic diagnostic imaging has proved useful in the screening of the trajectory of the epidural needle. With regard to possible side-effects of spinal and epidural anaesthesia caused by vessel injury, we aimed to evaluate the usability of Colour Doppler imaging for the depiction of interspinous vessels in prepuncture examination.

Methods Ultrasonic examination of the L¾ interspace area was performed in 20 volunteers. Using a 4-MHz and a 7-MHz probe with B-mode and Colour Doppler imaging, respectively, we compared four settings for the quality of vessel depiction in the puncture area. Overall resolution was evaluated according to the distinction of landmarks. Vascular structures were identified by pulsation (B-mode) or blood flow (Doppler).

Results Colour Doppler imaging of the L3/4 interspace was unachievable using the 7-MHz transducer. Vessel detection was possible in 50% of the B-mode images and in all of the 4-MHz Doppler images. Vessels were perceptible from a diameter of 0.5 mm. Veins were the predominantly visible structures. Overall vessel visibility was best using 4-MHz Colour Doppler.

Conclusions Prepuncture Doppler imaging can provide the epiduralist with information regarding the position of vessels in the needle trajectory. This might help to reduce complications in regional anaesthesia.

Despite the high frequency of sickle cell disease in Europe, the disease is poorly managed. Critical periods are the hospital stays during which the anaesthe-siologist plays an important role. Understanding the molecular basis of polymerization processes of haemoglobin S can help to avoid triggering a crisis. Differentiation of the various haemoglobin phenotypes helps to estimate the individual perioperative risk. Knowledge of the patient's history and the actual haemoglobin S level facilitates general anaesthesia, surgery and postoperative care. Damage to liver, spleen, eyes, bones, lung and central nervous system increases the perioperative risk. Preoperative preparation includes early admission, intravenous volume substitution, continuing pain therapy and prophylactic antibiotic medication. General anaesthesia seems to be better for patients with a high-risk profile rather than regional anaesthesia. Careful perioperative and postoperative monitoring should allow hypoxaemia, hypovolaemia, hypothermia, acidosis and overtrans-fusion to be avoided. Effective pain therapy includes a combination of opioids with peripherally acting analgesia.

Appropriate airway management is an essential part of the anaethetist's role. Difficult intubation, which can now be quantified using the ‘Intubation Difficulty Scale’, should be anticipated whenever possible. A strategy needs to be developed in order to anticipate problems. The first part of this paper reviews the different factors that contribute to make intubation and/or ventilation difficult. Problems with intubation (or ventilation of the lungs) can be caused by abnormal laryngeal structures (e.g. tumour, stenosis), or by difficulty in seeing the glottis. The clinical history will usually help identify the former problem, while physical examination of the airway is required to reveal either disproportion between the various structures of the airway (e.g. tongue, larynx), and/or difficulties in aligning the oral, pharyngeal, and laryngeal axes. The different techniques used to diagnose these problems are described. The second part of this paper summarizes the algorithms used by the anaesthetist when management of the airway is found difficult. Three situations are considered: (a) anticipated difficult intubation, for which awake fibreoptic intubation would appear to be the technique of choice in the majority of cases, (b) unforeseen difficult intubation in a patient whose lungs can be ventilated; here, various techniques for control of the airway will be briefly described, and (c) both tracheal intubation and lung ventilation are impossible; this is a life-threatening emergency, for which three solutions are proposed. These include use of the laryngeal mask airway, the Combi-tube®, or transtracheal ventilation. These situations will be analysed with the aim of proposing management strategies that always guarantee the safety of the patient.

Background and objective Numerous drugs have been used to prevent or to treat opioid-induced pruritus in the surgical setting. Their relative efficacy is not well understood.

Methods The methods employed involved the systematic search (MEDLINE, EMBASE, Cochrane library, bibliographies, without language restriction, up to June 2000) for full reports of randomized comparisons of any intervention which is thought to be anti–pruritic (active) compared with placebo or no treatment (control) in surgical (including labour) patients receiving opioids. The number of patients who had no pruritus were analysed using relative risk and number–neededto– treat with 95% confidence interval.

Results Twenty-two trials (1477 patients) were analysed. Two trials (66 patients), both with low-dose propofol, were on treatment of established pruritus; propofol had no anti-pruritic effect compared with Intralipid. In prophylaxis trials, the average incidence of pruritus with control was 59% (range, 10% to 100%). Most mu–receptor antagonists were efficacious: intravenous naloxone 0.25–2.4 μgkg−1 h−1, relative risk 2.31 (95% confidence interval, 1.5 to 3.54), numberneeded– to–treat to prevent pruritus compared with control 3.5; oral naltrexone 9 mg, relative risk 2.80 (1.35–5.80), number-needed-to-treat 1.7; naltrexone 6mg was less effective and 3mg did not work; different intravenous and epidural nalbuphine regimens, relative risk 1.71 (1.12–2.62), number-needed-to-treat 4.2. Intravenous nalmefene 0.5 or 1mg was not antipruritic. Intravenous (but not epidural) droperidol 2.5mg was efficacious, relative risk, 1.71 (1.28–2.29), number-needed-to-treat 4.9. There was a lack of evidence for any anti–pruritic efficacy with prophylactic propofol, epidural or intrathecal epinephrine, epidural clonidine, epidural prednisone, intravenous ondansetron, or intramuscular hydroxyzine.

Conclusion Naloxone, naltrexone, nalbuphine and droperidol are efficacious in the prevention of opioidinduced pruritus; minimal effective doses remain unknown. There is a lack of valid data on the efficacy of interventions for the treatment of established pruritus.

Diabetes mellitus is the most common metabolic disease and its incidence is increasing. New classifications have been recently proposed based upon a better knowledge of pathogenesis, mechanisms of glucose transport and insulin resistance. The perioperative care of diabetic patients is less dependent on blood-glucose control, which needs to be exceptionally tight, and is usually easily obtained thanks to pharmacological improvements, human insulins and analogues, technical progress with blood-glucose monitoring at the bedside and infusion with constant flow rates. More important is the influence of end-organ pathology, often clinically silent, which must be carefully assessed during the preoperative evaluation. The organ impairments concern especially the heart, but also all those organs that were modified by abnormal glycosylated proteins. The pre-existing pathology has many consequences on anaesthesia management; the anaesthetic technique depends essentially on their existence. A better long-term control of diabetes both for Type 1 and Type 2 by insulins, and the new oral anti-diabetic drugs reduce the incidence of the end-organ pathology and the risk linked to organ failures in the perioperative period.

Background and objective Midazolam may occasionally precipitate hostility and violence instead of tranquillity. We characterized these episodes, their rate of occurrence, the potential paradoxical responders and possible predisposing circumstances among patients undergoing lower body surgery under spinal or epidural anaesthesia and midazolam sedation.

Patients and methods Fifty-eight patients who fulfilled the study entry criteria and who underwent surgery within a 3-month period in a large metropolitan, university-affiliated hospital were enrolled. Sedation and restlessness in all patients were controlled by midazolam administered intravenously by the attending anaesthesiologist; these parameters were later objectively confirmed by recorded actigrams. If ‘paradoxical’ events occurred, flumazenil 0.1 mg 10 s−1 was injected until the aberrant behaviour ceased. Patients with paradoxical reactions were later compared with matched control patients selected from the study group to identify epidemiological characteristics.

Results The incidence of paradoxical events was 10.2% (six out of 58 patients, confidence limits 2.3–18.3%) and they occurred 45–210 min after sedation started; the only independent predictor was an age older than that of the entire study group. The mean cumulative and per weight doses of midazolam were similar for both the experimental and the study groups of patients: 7.3 ± 2.8 to 10.1 ± 3.6 mg, and 0.1 ± 0.04 to 0.12 ± 0.05 mg kg−1. Flumazenil 0.2–0.3 mg (range 0.1–0.5 mg) effectively stopped the midazolam-induced paradoxical activity within 30 s and surgery continued uneventfully.

Conclusions Flumazenil completely reverses midazolam-induced paradoxical reactions and they are more frequent in older patients.

Background and aim We investigated the haemody-namic stability and emergence characteristics of isoflur-ane/nitrous oxide anaesthesia supplemented with remifentanil or fentanyl in patients undergoing carotid endarterectomy.

Methods Anaesthesia was induced with propofol (1–2mgkg−1) and either remifentanil (O.5μgkg−1) or fentanyl (1 μgkg−1), followed by an infusion of remifentanil (0.2 μg kg−1 min−1) or fentanyl (2 μg kg−1 h−1).

Results There were no significant differences between the groups in haemodynamic variables, postoperative pain, nausea or vomiting. After induction there was a significant decrease in mean arterial pressure for both groups (P<0.001) and a decrease in heart rate (P=0.001) in the remifentanil group. In both groups these haemodynamic changes continued during maintenance of anaesthesia (P<0.05). The time to eye opening after surgery was significantly shorter with remifentanil compared with fentanyl (6.62±3.89 vs. 18.0±15.18min, P=0.015).

Conclusion Remifentanil appears to be a comparable opioid to fentanyl when supplementing isoflurane/nitrous oxide anaesthesia for carotid endarterectomy.

Background and objective Late postoperative hypoxaemia after upper abdominal surgery is common even among cardiopulmonary healthy patients. Atelectasis may develop after intubation and persist into or reveal a disposition for atelectasis in the postoperative period. Positive end–expiratory pressure (PEEP) eliminates peroperative atelectasis but the effect on perioperative oxygenation is controversial. This study evaluated the effect of peroperative PEEP optimized pulmonary compliance on perioperative oxygenation and complications.

Methods Forty patients assessed by electrocardiography, spirometry, functional residual capacity and diffusion capacity were randomly assigned to receive positive end–expiratory pressure (PEEP) or zero endexpiratory pressure (ZEEP) during surgery. PaO2, SPO2 and complications in the postoperative period were evaluated without knowledge of peroperative PEEP or ZEEP application.

Results Peroperative arterial oxygenation improved for all patients receiving PEEP, mean 2.1 kPa (0.7–3.5 kPa). There was no difference in postoperative median PaO2 between the groups. The differences in the incidence of late prolonged postoperative hypoxaemia and complications were 25% (−5% to 55%) and −1% (−31% to 29%) between the ZEEP and the PEEP group, but were not statistically significant.

Background and objective Transoesophageal echocardiography is increasingly used for evaluation and monitoring of left ventricular function in anaesthetized patients. However, the only available reference values for transoesophageal echocardiography were derived from studies in awake subjects.

Methods We determined left ventricular dimensions and systolic function in 45 patients without clinical evidence of heart disease who voluntarily underwent transesophageal echocardiography under conditions of balanced general anaesthesia, controlled fluid administration, supine position, muscle relaxation and controlled ventilation.

Results The left ventricular dimensions obtained during these conditions were lower than the published normal values in awake subjects. The indices of global left ventricular function, however, were similar to the normal values obtained by either awake transesophageal echocardiography or transthoracic echocardiography.

Conclusion We propose using the values obtained in our study as reference values for evaluation of left ventricular function in patients under general anaesthesia and controlled ventilation.

Background and objective Volatile anaesthetic effects on altering tone after blocking nitric oxide synthase, cyclo-oxygenase-prostaglandin synthase and KATP channel pathways are controversial. We examined in isolated guinea pig hearts whether anaesthetics alter bradykinin and 5-hydroxytryptamine-induced effects on coronary flow and percentage oxygen extraction after blocking these pathways.

Methods Before and during exposure to sevo-flurane, halothane or isoflurane, hearts were infused with 10−13–10−8 M bradykinin, or 10−8–10−6 M 5-hydroxytryptamine (serotonin), with either L-NAME, indomethacin, or glibenclamide. Bradykinin or 5-hydroxytryptamine alone increased flow and decreased percentage oxygen extraction in a concentration-dependent manner; these effects were largely blocked by L-NAME (nitro-L-arginine methylester), which also decreased basal flow and increased basal percentage oxygen extraction.

Results The anaesthetics restored bradykinin and 5-hydroxytryptamine-induced increases in flow or decreases in percentage oxygen extraction after inhibition by L-NAME. Indomethacin or glibenclamide alone had little effect on basal flow and percentage oxygen extraction. The anaesthetics restored bradykinin and 5-hydroxytryptamine-induced increases in flow or decreases in percentage oxygen extraction after inhibition by L-NAME. Indomethacin or glibenclamide alone had little effect on basal flow and percentage oxygen extraction. Drug-induced increases in flow and decreases in percentage oxygen extraction in the absence or presence of glibenclamide or indomethacin were not altered at either of the two concentrations of anaesthetics.

Conclusions Endothelium-dependent vasodilatation is not affected by blocking prostaglandin release or KATP channels in the intact heart even in the presence of an anaesthetic. However, the diminished responses to vasodilators after nitric oxide synthase inhibition is largely restored or enhanced by anaesthetics.

Background and objective The aim of this study was to determine possible age-associated differences in human blood pressure regulation during an immunological challenge in healthy subjects.

Methods Eight healthy young volunteers (median age 24 yr) and nine healthy elderly volunteers (median age 66 yr) received an intravenous bolus injection of Eschericia coli endotoxin (2 ng kg−1). Blood pressure, heart rate and core temperature were monitored during the first 7 h. Plasma catecholamine concentrations were measured at hourly intervals.

Results The elderly showed a significantly more pronounced decrease in mean arterial pressure 4–7 h after endotoxin administration compared with the young controls (anova; age × time; P < 0.0005). This mainly reflected a decrease in the systolic blood pressure in the elderly. The heart rate of both groups increased without difference between groups. Increased plasma epinephrine concentrations were found 2–3 h after endotoxin administration in both groups. Five hours after the endotoxin challenge, the epinephrine concentration had returned to control values in the elderly group only, in spite of decreased blood pressure.

Conclusion In conclusion, healthy elderly subjects fail to maintain a constant mean arterial pressure in response to the immunological challenge of endotoxemia.

Background and objective Polymorphonuclear leucocytes make a decisive contribution to defence against bacterial infections. In particular, the effects of anaesthetics on non-oxidative bactericidal mechanisms have previously only been superficially examined. Although the influence of anaesthetic agents on oxi-dative bactericidal activity has been thoroughly examined, our study concentrated on the effect on non-oxidative processes, which appears to have been a neglected field of research.

Methods The effects of methohexital, etomidate, ketamine, fentanyl and morphine on the activity of lysozyme and β-glucuronidase released from polymorphonuclear leucocytes have been studied in vitro. The activity of lysozyme was determined by recording the changes in the turbidity of a suspension of micro-coccus lysodeicticus caused by the enzymatic action of lysozyme. β-glucuronidase activity was photometrically measured by the enzymatic cleavage of phe-nolphthalein glucuronic acid.

Results High concentrations of methohexital inhibited lysozyme activity; however, etomidate and morphine caused an increase of β-glucuronidase activity in therapeutic plasma concentrations. While there was no effect of etomidate on lysozyme activity, all concentrations tested significantly stimulated β-glucuronidase activity. This result was unexpected because intravenous anaesthetics have previously shown a tendency to suppress polymorphonuclear leucocyte functions. Whereas the inhibition of lysozyme activity by the high concentration of methohexital was no surprise, the increase of β-glucuronidase activity caused by etomidate, ketamine, fentanyl and morphine was quite unexpected.

Conclusions At present, the underlying mechanism for the increase of β-glucuronidase activity caused by etomidate, ketamine, fentanyl and morphine is unknown. The fact that there was no influence of these agents on lysozyme activity possibly suggests that the anaesthetic agents have different effects on azurophilic and specific granules. Since in vitro investigations have their limitations, it is too early to draw practical consequences from our study. Moreover, at present it is unclear whether an increase of β-glucuronidase activity in vivo is an advantage or not. In any case, we think it advisable to perform further investigations on the influence of anaesthetic agents on oxygen-independent bactericidal mechanisms.

Background and objective This study investigates the interaction of sevoflurane and nitrous oxide on EEG median power frequency of 2.5 Hz during surgery.

Methods Sevoflurane concentrations required for electroencephalographic median power frequency between 2 and 3 Hz were measured in 25 patients during gynaecological laparotomies. Nitrous oxide was randomly administered at 0, 20, 40, 60 and 75 vol%, subsequently two different concentrations in each patient. The data were analysed using isobolographic analysis together with previously published data on nitrous oxide-isoflurane, -enflurane, or -desflurane interaction.

Results The interaction is described by the equation: C volatile anaesthetic/C0 volatile anaesthetic + C N2O/C0 N2O = 1 (C is the concentrations for a drug combination to achieve the desired effect; C0 is the concentration for single drug use). The parameters are C0 isoflurane = 1.11 vol% (95% CI 1.03–1.19), C0 enflurane = 1.64 (1.52–1.77), C0 desflurane = 5.31 (4.92–5.73), C0 sevoflurane = 2.12 (1.96–2.29), C0 N2O = 174 (153–202). These parameters decrease by 6% (2.5–10) for every 10 years of patients’ age > 40 years.

Conclusions The interaction is compatible with additivity. The potency of nitrous oxide to substitute the volatile anaesthetics is less than anticipated from previously reported MAC values.

Background and objective The recently developed transcerebral double-indicator dilution technique has proven to be a feasible monitoring alternative to measure global cerebral blood flow at the bedside. However, the short-term repeatability of transcerebral double-indicator dilution measurements has not yet been investigated. The present study was designed to investigate the accuracy in terms of reliability for repeated transcerebral double-indicator dilution measurements to assess global cerebral blood flow during a definite carbon dioxide challenge in a clinical trial.

Methods The investigation was performed in 10 patients scheduled for elective coronary artery bypass grafting. After induction of anaesthesia, repeated cerebral blood flow measurements using transcerebral double-indicator dilution were performed during target normocapnia, hypocapnia and hypercapnia. For transcerebral double-indicator dilution measurements, a bolus injection of ice-cold indocyanine green was administered into a central vein. The resulting thermal dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fibreoptic thermistor catheters. Cerebral blood flow was calculated from the mean transit times of the indicators through the brain. Additionally, transcranial Doppler sonography was simultaneously performed to measure transient changes in the cerebral blood flow velocity.

Results Transcerebral double-indicator dilution measurements revealed a reasonable coefficient of repeatability with 9.1, 9.7 and 20.2 mL min−1100 g−1 during normo-, hypo- and hypercapnic conditions, respectively. However, a total of 20% of the administered measurements had to be rejected for methodological reasons.

Conclusions Repeated measurements with the transcerebral double-indicator dilution method show a reasonable repeatability. With consideration to the limitations of the transcerebral double-indicator dilution technique, this new method proves to be a reliable monitoring tool to measure global cerebral blood flow at the bedside.

Background and objective This study compares the effect of oral clonidine vs. hydroxyzine on the haemodynamic and catecholamine responses to microlaryngoscopy.

Methods Thirty-five ASA II-III patients were included in this double-blind randomized trial. The patients received either hydroxyzine 1 mg kg−1 (n=18) or clonidine 3 μg kg−1 (n = 17) for their oral premedication 100 min before an intravenous induction of anaesthesia using propofol (2–3 mg kg−1) and fentanyl (2 μg kg−1). Arterial pressure and heart rate were measured before premedication, and throughout the procedure and recovery. Plasma catecholamine levels were determined before premedication, after induction, and 1.5, 30 and 120 min after laryngoscopy.

Results Mean arterial pressure was significantly lower after clonidine, whereas there was no difference in heart rate and plasma catecholamine levels between the two groups.

Conclusions Clonidine for premedication significantly decreased mean arterial pressure during microlaryngoscopy and the following recovery phase but did not modify the overall haemodynamic response to the suspension microlaryngoscopic nociceptive stimulus.

Background and objective Serum hyaluronate is thought to be an indicator of derangement in hepatocellular integrity, and the change in serum hyaluronate is a useful indicator in various liver disorders. We assessed the changes in serum hyaluronate in patients undergoing coronary artery bypass graft surgery.

Methods Eleven patients scheduled for elective coronary artery bypass graft surgery were studied. An oximetry oxygen saturation catheter was inserted into the right hepatic vein to permit monitoring of hepatic venous oxygen saturation. Perioperative measurements included: haemodynamic variables; systemic oxygen delivery and uptake; arterial, mixed venous and hepatic venous oxygen saturation; arterial and hepatic venous plasma concentrations of lactate, arterial ketone body ratio (ratio of acetoacetate to 3-hydroxybutyrate); and arterial and hepatic venous hyaluronate were measured.

Results Arterial and hepatic venous hyaluronate increased during cardiopulmonary bypass compared with the prebypass period. These increases returned to prebypass values after the cessation of bypass (hepatic venous hyaluronate value at the prebypass period: 26 ± 13 ng mL−1, during bypass: 77 ± 40 ng mL−1; 1 h after bypass: 57 ± 42 ng mL−1; 6 h after bypass: 32 ± 15 ng L−1, 24 h after bypass; 62 ± 21 ng mL−1; mean ± SD, P < 0.05). The arterial and hepatic venous hyaluronate during cardiopulmonary bypass was correlated with total bilirubin and hepatic venous lactate concentrations 6 h after bypass (arterial hyaluronate at cardiopulmonary bypass period vs. total bilirubin at 6 h after bypass; r = 0.793, P = 0.0036, hepatic venous hyaluronate during bypass vs. that at 6 h after bypass; r = 0.795, P = 0.0035).

Conclusions Hepatocellular integrity might be disturbed during cardiopulmonary bypass when propofol anaesthesia is used.

Background and objective Low-flow anaesthesia is economical and less polluting. The purpose of this study was to determine the inspired and end-tidal desflurane concentrations during anaesthesia with a vaporizer setting maintained at 5%, during low-flow anaesthesia after 120 min with fresh gas inflows of 1.0 and 2.0 L min−1.

Methods The study was both prospective and randomized, including 56 patients (28 patients in each group) scheduled for elective surgery of an expected anaesthesia time of at least 120 min. Inspired and end-tidal concentrations of desflurane were measured during low-flow anaesthesia with fresh gas inflows of 1.0 and 2.0 L min−1. The vaporizer setting was fixed at 5% desflurane.

Results The inspired and end-tidal concentrations of desflurane in the 1.0 L min−1 group after 120 min were 4.54% vs. 4.37% (P < 0.001). In the 2.0 L min−1 group, the inspired and end-tidal concentrations of desflurane were 4.76% vs. 4.58% (P < 0.001). The estimated end-tidal/inspired ratios at 120 min of anaesthesia were 0.96 in both groups. At a fresh gas flow of 1.0 L min−1, the end-tidal concentration was 0.87 of the vaporizer setting. Increasing the fresh gas flow to 2.0 L min−1 increased the end-tidal value by 0.05.

Conclusion There is a significant difference between the inspired and end-tidal concentrations of desflurane when fresh gas inflows were 1.0 and 2.0 L min−1, but not for the ratio of inspired/end-tidal.

Newer anaesthetic agents provide a faster onset, easier titration and a more rapid recovery than the older agents, but are more expensive. In assessing the financial consequences associated with their use, it is important to examine the total costs (including personnel costs) and not just the acquisition costs of new drugs. Claims of cost savings from new drugs should be subjected to close scrutiny, with studies designed to demonstrate that the preferential use of the newer drug is associated with actual decreased payments for personnel, an earlier return to normal activities by the patient and/or their caretakers, or the completion of an additional case in the same operating session. It may be necessary to alter work patterns to obtain the full benefits of the new drugs (e.g. bypass of the labour-intensive [phase I] postanaesthetic care unit). Finally, greater cost savings in the operating room can be achieved by increasing efficiency in resource utilization. A delay in starting a case, or a prolonged turnover time between cases, can negate any cost savings related to the anaesthetist's choice of drugs.

Background and objective Increased glutamate concentration in the cerebrospinal fluid has been reported in severely head–injured patients, suggesting that an excessive release of glutamate may be involved in the process of neuronal damage. Ischaemic damage after subdural haematoma has been reported to be reduced by glutamate (N-methyl-D-aspartate: NMDA) receptor antagonists such as dizocilpine and CGS 19755; even though these drugs were given 20–30 min after insult. Excessive release of excitatory amino acids may produce the neural damage after subdural haematoma and NMDA receptor antagonists may become valuable therapeutic drugs. This study compared the effects of ketamine and dizocilpine, on intracranial pressure and histopathological changes after acute subdural haematoma produced by an injection of autologous blood (150 μL) in rats.

Methods The control (n =9), ketamine (n =9) and dizocilpine (n =9) groups, respectively, received saline, ketamine (total dose: 210 mgkg−1) or dizocilpine (total dose: 1.0 mgkg−1) from 0.5 to 8 h after acute subdural haematoma. A silicone group (n =9) had the same volume of silicone injected subdurally.

Results The volume of ischaemic damage in the silicone group (1.3±1.2mm3) was significantly smaller than in the control group (11.9±3.8mm3). Ketamine and dizocilpine did not increase intracranial pressure. Dizocilpine significantly decreased the volume of ischaemic damage (6.1±3.8mm3). Ketamine failed to significantly decrease damage (7.8±5.0mm3).

Conclusions These results suggest that the factors elicited by the clotted blood contribute to the ischaemic damage after subdural haematoma, and that the glutamate receptor antagonist dizocilpine reduces the damage, while ketamine shows only a trend reduction of the damage.