Stewart’s and Fencl’s methods have recently been proposed to interpret acid–base disorders where traditional theory has proven inadequate. Our objectives were to evaluate: (1) the occurrence of acid–base disturbances in critically ill patients and their trend over the first 3 intensive care unit days, (2) whether Stewart’s theory offers advantages over the traditional theory in the diagnosis of acid–base metabolic disturbances and (3) whether variables derived from Stewart’s and Fencl’s methods offer advantages over the traditional method to predict patient mortality.

A prospective cohort study in a general intensive care unit. Blood samples were analysed for arterial blood gases, electrolytes and proteins. PaCO2, pH, bicarbonate, base excess, standard base-excess, sodium, potassium, chloride, phosphorous, calcium, magnesium and lactate were measured. Anion gap, Stewart’s and Fencl’s variables were calculated.

When using Stewart’s method, metabolic acidosis and metabolic alkalosis were found in 92.9% and 93.4% of samples, respectively. Corresponding figures obtained with the traditional method were 15% and 18.7%. In 245 (64.5%) samples, Stewart’s method revealed that metabolic acidosis and alkalosis were simultaneously present, whereas the traditional method revealed a normal acid–base status. Strong ion gap increased significantly over the first 3 intensive care unit days. Strong ion gap and lactate were independent predictors of 28-day mortality.

Metabolic acidosis by unmeasured anions is a clinically relevant phenomenon, which is correlated with mortality. Progressive metabolic acidosis may be ongoing in the early phase of critical illness despite the absence of acidaemia.

Intraoperative Doppler ultrasound can be used to measure cardiac output by transoesophageal echocardiography. Recently, its reliability, when compared to the thermodilution technique, has been questioned. The purpose of this study was to compare intraoperative changes in cardiac output measured by echo-Doppler and by thermodilution in cardiac surgery. We also assessed the agreement between the techniques.

Fifty cardiac surgical patients (38 male, 12 female, mean age of 63.4 ± 14.3 yr) were prospectively included after approval by the Ethics Committee of the Institution. Cardiac output was assessed by thermodilution, with 10 mL saline at 12°C, and simultaneously and blindly by echo-Doppler in deep transgastric view with pulsed wave Doppler at the level of the left ventricular outflow tract. Matched thermodilution cardiac output and echo-Doppler cardiac output measurements were taken three times at the end of expiration, both pre- and post-cardiopulmonary bypass.

Echo-Doppler measurements were obtained in 44 patients (88%). In three patients, Doppler recordings could not be obtained adequately, and three developed left ventricular outflow tract obstruction after bypass. Bland–Altman analysis revealed a bias of 0.015 L min−1, with narrow limits of agreement (−1.21 to 1.22 L min−1) and 29.1% error. Echo-Doppler was accurate (92% sensitivity and 71% specificity, P = 0.008 by receiver operating characteristic curves) for detecting more than 10% of change in thermodilution cardiac output. There were no complications related to the study.

The agreement between cardiac output by echo-Doppler and by thermodilution is clinically acceptable and transoesophageal echocardiography is a reliable tool to assess significant cardiac output changes in a population of selected patients.

Despite its popularity, serious complications do occur with percutaneous dilatational tracheotomy in the ICU. The associated risks in daily practice are probably underestimated and may reflect system flaws in training and team function. This study was performed to obtain an impression of risk perception and safety culture in connection with percutaneous dilatational tracheotomy in Norwegian ICUs.

The Medical Director or intensivist on-call in the 30 ICUs participating in the Norwegian Intensive Care Registry was telephone interviewed using a semi-structured questionnaire. Data on the practice of tracheotomy and a qualitative assessment of complications experienced during the last 2 years were collected. In the second part, percutaneous dilatational tracheotomy operators in two ICUs were questioned about their perception of risk with percutaneous dilatational tracheotomy and asked to assess their own abilities as percutaneous dilatational tracheotomy operators and the training they had undergone.

Of the 30 ICUs, 23 used percutaneous dilatational tracheotomy. The majority reported knowledge of severe complications like bleeding, hypoxia and tube dislodgment. Percutaneous dilatational tracheotomy-related deaths were also reported. Operators rated themselves relatively low and indicated the absence of any organized training. They acknowledged the known hazards related to percutaneous dilatational tracheotomy and suggested measures like fibreoptic guidance during the percutaneous dilatational tracheotomy and fewer operators with more experience as well as better team training, to improve patient safety.

Based on the frequent reporting of serious complications and the suggested safety precautions, we conclude that the percutaneous dilatational tracheotomy is considered a high-risk procedure and that there is still room for improving the safety of this much used ICU procedure.

Epidural volume extension via a combined spinal–epidural is the enhancement of a small-dose intrathecal block by an epidural injection of physiological saline solution. We evaluated the effect of epidural volume extension on the combined spinal–epidural technique of providing spinal anaesthesia for Caesarean section with hyperbaric or plain 0.5% bupivacaine.

Patients (n = 240) with height >163 cm received 9 mg and patients <163 cm received 8 mg of bupivacaine. Each study drug was combined with 20 μg fentanyl. Using the combined spinal–epidural technique, Group A (n = 60) received hyperbaric bupivacaine, and Group B (n = 60) received hyperbaric bupivacaine and 10 mL saline epidurally 5 min after subarachnoid injection. Group C (n = 60) received plain bupivacaine and Group D (n = 60) received plain bupivacaine and 10 mL saline epidurally 5 min after subarachnoid injection. An anaesthetist blinded to the anaesthetic solution injected examined the level of analgesia by the pinprick method and motor block with the modified Bromage scale for 30 min after subarachnoid injection, during the intraoperative period and subsequently every 15 min for 135 min during the recovery period.

Time to reach a sensory block at T4 was significantly shorter in Groups C and D than in Groups A (P = 0.003 and 0.017) and B (P = 0.006 and 0.048), respectively. During the intraoperative period, sensory block levels were significantly higher in Group C than in Group A. Recovery was similar in all groups; only onset was faster in Groups C and D.

There was no effect of epidural volume extension on the profile of spinal anaesthesia with the combined spinal–epidural technique for Caesarean section using hyperbaric or plain bupivacaine.

The myocardial performance index is a non-geometric, heart rate-independent echocardiography-derived index of left ventricular performance combining systolic and diastolic function. There is an ongoing debate whether the myocardial performance index is affected by preload or not. Moreover, a systematic evaluation of the effect of changing tidal volume ventilation on the myocardial performance index is still lacking. The aim of our study was to assess whether acute changes in preload and/or different depth of tidal volume ventilation affect the myocardial performance index.

In all, 14 anesthetized pigs (35 ± 2 kg) were studied during changing tidal volumes (VT 5, 10 and 15 mL kg−1) at baseline, after removal of 500 cm3 of blood (haemorrhage) and after retransfusion of shed blood plus additional 500 cm3 6% hydroxyethyl starch (fluid loading). Echocardiographic measurements at each experimental stage included myocardial performance index, left ventricular end-diastolic area and fractional area change. Central venous pressure, pulmonary capillary wedge pressure, cardiac output and stroke volume index were obtained by a pulmonary artery catheter. Global end-diastolic volume was obtained by transpulmonary thermodilution.

Comparing different loading conditions, we found significant changes in cardiac output, stroke volume index, central venous pressure, pulmonary capillary wedge pressure, global end diastolic volume and left ventricular end-diastolic area, indicating clinically relevant changes in preload. In the haemorrhage group, there was a significant reduction in the myocardial performance index (P < 0.05) independent of tidal volume applied and this was reversed after fluid loading. However, myocardial performance index was significantly impaired (P < 0.05) by high tidal volume ventilation (15 mL kg−1), while tidal volumes of 5 and 10 mL kg−1 had no effect.

The myocardial performance index is largely dependent on changes in preload. Moreover, high tidal volume ventilation significantly impaired the myocardial performance index.

Our aim was to investigate the cytoprotective effect of propofol against hydrogen peroxide (H2O2)-mediated injury and the effects on the haeme oxygenase-1 system, which is a possible new cytoprotective pathway of propofol.

Primary cultured newborn rat cardiomyocytes were divided into five groups: (1) untreated (Group control); (2) treated with 200 μmol L−1 H2O2 (Group H) and treated with 200 μmol L−1 H2O2 in the presence of propofol (25, 50 and 100 μmol L−1, (3) Group 25P + H, (4) Group 50P + H and (5) Group 100P + H, respectively); added with zinc protoporphyrin IX (ZnPPIX) (10 μmol L−1), a potent inhibitor of haeme oxygenase activity, or SC-3060 (0.2 μL mL−1), a specific synthetic inhibitor of nuclear factor κB. All were incubated for 6 h. The protective effects of propofol were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide cytotoxicity assay, the concentration of malondialdehyde, superoxide dismutase activity and cell apoptosis by enzyme-linked immunosorbent assay (ELISA). Reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis were used to detect haeme oxygenase-1 expression.

Compared with H2O2, propofol concentrations (ranging from 50 to 100 μmol L−1) significantly increased haeme oxygenase-1 expression and decreased cardiomyocytes apoptosis, accompanied with a decrease in malondialdehyde, but with an increase in superoxide dismutase activity and cell activity (P < 0.05 and P < 0.01, respectively). The protective effects of propofol were mitigated by the addition of ZnPPIX. The addition of SC-3060 reversed propofol-induced haeme oxygenase-1 expression.

Propofol can protect cardiomyocytes against H2O2-mediated cytotoxicity in a dose-dependent manner and increase haeme oxygenase-1 expression, which may partly mediate the cytoprotective effects of propofol.

Pentobarbital and ketamine are commonly used in animal experiments, including studies on the effects of ageing on the central nervous system. The electroencephalogram is a sensitive measure of brain activity. The present study investigated, under anaesthesia induced by the two drugs, whether cortical electroencephalogram in aged rats differs from that in young rats.

Electroencephalogram was recorded for young (2–3 months) and aged (15–17 months) rats before and during pentobarbital (40 mg kg−1) or ketamine (100 mg kg−1) anaesthesia. The relative power in five frequency bands (delta: 2–4 Hz; theta: 4–8 Hz; alpha: 8–12 Hz; beta: 12–20 Hz; gamma: 20–100 Hz) was analysed, and then compared between the two age groups.

In both age groups, pentobarbital anaesthesia induced an increase in relative power in alpha and beta bands and a decrease in the theta band, but the degree of these power variations was more marked in aged rats. Ketamine anaesthesia increased relative power in the delta band and decreased that in the theta band; these effects were significantly different between the two age groups, with aged rats showing more markedly decreased power in the theta band.

(a) Pentobarbital and ketamine modified cortical electrical activity in a different manner as a function of age; (b) the modification of electroencephalogram relative power with anaesthesia was identical in young and aged rats but quantitatively more marked in aged rats. These findings will be useful in designing experiments that assess pathological changes in the central nervous system during ageing.

We investigated cerebrospinal fluid characteristics in patients with and without diabetes mellitus and the influences that changes in these characteristics have on sensory and motor block when spinal anaesthesia is performed.

We included 44 patients in each study group. All received spinal administration of 15 mg of 0.5% isobaric bupivacaine. Blood and cerebrospinal fluid were analysed for glucose, total protein, urea, albumin, immunoglobulin G, sodium, chloride, potassium, calcium, magnesium and osmolarity as well as the performance of the local anaesthetic from establishment until complete regression of sensory and motor block.

The cerebrospinal fluid of the two groups differed significantly (P < 0.05) in the levels of total protein, albumin, immunoglobulin G, glucose and osmolarity. Sensory and motor block was established more rapidly in the diabetic group (P < 0.05), and the total duration from maximum block until regression to two dermatomes was greater (P < 0.05), as was the complete regression from sensory and motor block (P < 0.05).

This study shows that diabetes mellitus has an influence on sensory and motor block after the administration of spinal isobaric bupivacaine.

Levosimendan is a calcium-sensitizing drug that enhances myocardial contractility without increasing intracellular calcium. By activating adenosine triphosphate-dependent potassium channels it exerts cardioprotective and vasodilatory effects.

A retrospective matched pair analysis was performed in 52 patients undergoing emergency coronary artery bypass grafting for acute myocardial ischaemia with or without cardiogenic shock. A total of 27 patients received levosimendan (bolus 6 μg kg−1; continuous infusion 0.2 μg kg−1 min−1) in addition to catecholamines, while 25 patients were treated with catecholamines only.

Predicted mortality by logistic EuroSCORE was 42% (14–90%) in the levosimendan group and 38% (9–90%) in the control group (median, range). Cardiogenic shock was diagnosed in 52% of the patients in both groups. Compared to the control group, levosimendan-treated patients had fewer intra-aortic balloon pumps inserted (33% vs. 76%, P < 0.05) and were ventilated for a shorter period (39 ± 39 h vs. 106 ± 109 h, P < 0.05). In this limited number of patients, the reduction in mortality at day 30 (26% levosimendan; 44% control, P > 0.05) and need for dialysis (11% levosimendan; 32% control, P > 0.05) did not reach statistical significance. Length of hospital stay did not differ (14 ± 18 days, levosimendan; 13 ± 19 days, control; P > 0.05) between the two groups.

In this retrospective matched pair analysis of 52 patients undergoing emergency coronary artery bypass grafting for acute ischaemia, levosimendan reduced morbidity. The reduced morbidity did not translate into reductions in mortality or length of stay. A larger, prospective randomized trial is warranted to confirm the potentially beneficial effects of levosimendan in patients with acute ischaemia.

We have previously demonstrated, in the isolated rat heart, that propofol attenuates hydrogen peroxide-induced damage and ischaemia-reperfusion injury, and that the beneficial effect of propofol is correlated with reduction of the lipid peroxidation. This study was designed to evaluate whether propofol has a cardioprotective effect against ischaemia-reperfusion injury in a rat model in vivo.

Adult rats were anaesthetized with pentobarbital 10 mg kg−1 h−1 alone (control group), pentobarbital 10 or 20 mg kg−1 h−1 + Intralipid® as a vehicle (Pent-10, Pent-20 group), propofol 10 or 20 mg kg−1 h−1 (Prop-10, Prop-20 group) intravenously throughout the experiment. The left anterior descending coronary artery was occluded for 30 min followed by 120 min of reperfusion. Infarct size was determined at the end of reperfusion. The tissue concentration of malondialdehyde was measured at 30 min after reperfusion to evaluate lipid peroxidation.

The infarct sizes (% of area at risk) were significantly smaller in the Prop-10 (54 ± 11%; P < 0.01 vs. control) and Prop-20 (39 ± 8%; P < 0.01 vs. control) groups than in the control (68 ± 9%), Pent-10 (69 ± 13%) and Pent-20 (68 ± 14%) groups (n = 12). In the Pent-10 and Pent-20 groups, ischaemia-reperfusion produced significant increases in the values for tissue malondialdehyde (0.72 ± 0.24 μmol mg protein−1; P < 0.05 and 0.63 ± 0.33 μmol mg protein−1; P < 0.05 vs. 0.46 ± 0.22 μmol mg protein−1 in non-ischaemic hearts, n = 8). However, the values of malondialdehyde in the Prop-10 and -20 groups were suppressed by 41% and 63%, respectively, compared with the Pent-10 group (P < 0.01).

Our results suggest that propofol could be cardioprotective against ischaemia-reperfusion injury dose dependently in a rat model in vivo and that the beneficial action of propofol may be correlated with its antioxidant effect.

The reliability of the Bispectral Index for evaluating and monitoring the depth of general anaesthesia in children is not as great as for that in adults. Therefore we analysed Bispectral Index performance in children by comparing changes in Bispectral Index values during a standardized and equipotent anaesthetic regimen using either halothane or sevoflurane for the induction and maintenance of general anaesthesia. Special interest was focussed on excitation during induction, and whether it was associated with simultaneous changes in Bispectral Index scores.

Twenty children (3–15 yr, ASA I–II) scheduled for general surgery were randomly allocated to either halothane (10 patients) or sevoflurane group (10 patients). Anaesthesia was induced by 3% halothane or 7% sevoflurane, either agent administered with 50% N2O in oxygen for 5 min, the period from the beginning of induction until intubation. Thereafter, anaesthesia was maintained by the respective volatile agent at 1 MAC (minimum alveolar concentration; in addition to 70% N2O in oxygen) and supplemented with remifentanil infusion adjusted to maintain the heart rate and mean arterial pressure to within 20% of the baseline values. Excitation at induction was defined as involuntary muscular movements.

Sevoflurane induction produced a more rapid depression in Bispectral Index than halothane, the mean difference being greatest (47 Bispectral Index score) at 105 s. Excitation occurred in three patients during sevoflurane induction, which coincided with increases in Bispectral Index values in two of the three patients. During the maintenance phase at 1 MAC, the Bispectral Index (mean ± SD) was 57±7 for halothane and 47±9 for sevoflurane (P < 0.05). The remifentanil doses did not differ between both groups.

In children, halothane anaesthesia was associated with higher Bispectral Index values than sevoflurane when administered at 1 MAC. Large individual variation in Bispectral Index occurred within both groups. Due to these limitations, one should be cautious when interpreting paediatric Bispectral Index data.

To evaluate the current clinical attitude in enteral nutrition support and motility disorders in adult critically ill patients on German intensive care units.

A total of 1493 questionnaires, including 25 items on the medical environment, treatment of motility disorders and enteral nutrition, were sent to German intensive care units in September 2005. Responses were collected during a 2-month period.

A total of 593 questionnaires were returned (response rate 41%). The intensive care units were mainly led by anaesthesiologists (63%) or internists (17%). Standard nutrition protocols were used in 44%. Feeding was mainly started as a combined enteral–parenteral regimen (70%). Early enteral nutrition was performed in 58% using a volume of 250–500 mL (66%) and increased by 200–400 mL day−1 (55%). It was mainly delivered by gastric tube (76%) via continuous pump systems (72%) with short interruption intervals of <4 h (86%). Enteral nutrition solutions were mainly standard polymeric formulae (86%). Modified solutions for diabetics and those with renal or liver failure were uncommonly used; immunonutrition did not play a role. Prokinetic agents, especially metoclopramide, laxatives and neostigmine, were routinely used (39%). Further therapeutic options in motility dysfunction included purgative enemas (96%), gastrografin (72%) and colon massage (39%).

The concept of early enteral nutrition has been well established and approved in German intensive care units, though the recommendations only meet level C criteria in the current ESPEN guidelines. The current survey may serve for further updates on practical nutrition support in intensive care medicine.

To evaluate the use of remifentanil–propofol administered as target-controlled infusion during awake fibreoptic intubation for anticipated difficult tracheal intubation in acromegalic patients.

In all, 20 consecutive acromegalic patients underwent elective endonasal endoscopic transsphenoidal pituitary surgery. After premedication with midazolam 0.03 mg kg−1, initially a target-controlled infusion of remifentanil 1.0 ng mL−1 and propofol 1.5 μg mL−1 was started. The fibreoptic intubation was performed by the same physician experienced with the fibreoptic technique. During the fibreoptic procedure the target concentrations of remifentanil and propofol ranged between 1.0 and 5.0 ng mL−1, and between 1.5 and 3.5 μg mL−1, respectively. Changes in heart rate and mean arterial pressure were recorded during airway manipulation, during tracheal intubation, and at 1 and 3 min after. On the first postoperative day, patient recall and level of discomfort during fibreoptic intubation were evaluated.

Endotracheal intubation was efficaciously and quickly secured in all patients. A significant increase in mean arterial pressure and heart rate was recorded only during tracheal intubation (P < 0.05). Oxygenation was sufficient and no bradypnea or apnoea was recorded. All patients later described their anaesthetic experience as satisfactory. During fibreoptic intubation, remifentanil (ng mL−1) and propofol (μg mL−1) mean effect-site concentrations were 3.2 ± 0.3 and 2.0 ± 1.0, respectively.

Remifentanil and propofol target-controlled infusion provided satisfactory conscious sedation allowing for successful oral fibreoptic intubation in acromegalic patients with no recall.

Continuous monitoring of cardiac output during liver transplantation is essential to evaluate the patient’s haemodynamic tolerance to acute volume variations. The aim of this study was to compare the cardiac output values obtained with a transoesophageal echo-Doppler and those obtained with a continuous thermodilution cardiac output pulmonary artery catheter.

Twenty adult patients were prospectively studied during a 5 min hepatic vascular exclusion test performed at the end of the dissection phase. Echo-Doppler and continuous thermodilution cardiac output, mean arterial pressure and end-tidal CO2 were measured before and at the end of the test.

Before the test, echo-Doppler cardiac output was 7.0 ± 2.7 L min−1 and thermodilution was 9.4 ± 3.1 L min−1, (R = 0.85, P < 0.001). The end test values were, respectively, 3.5 ± 2.7 and 7.8 ± 3.5 L min−1 (R = 0.23, P = 0.34). Bland and Altman analysis showed a bias of −2.2 before the test, which increased to −4.4 at the end of the test. Mean arterial pressure decreased from 85.5 ± 15 to 66.8 ± 16 mmHg, end-tidal CO2 from 31.4 ± 2.3 to 23.8 ± 2.7 mmHg.

Echo-Doppler cardiac output values are different from those measured by thermodilution cardiac output in these patients. Echo-Doppler cardiac output monitoring seems to detect the output changes, which can occur during acute haemodynamic changes more rapidly than thermodilution cardiac output in the course of liver transplantation.

Cannulation of a central vein is an everyday procedure in anaesthesiology. However, anatomical variations of the size and/or location of the internal jugular vein might prevent cannulation, while repeated efforts might lead to severe complications. The aim of this retrospective study was to explore anatomical abnormalities of the internal jugular vein with regard to diameter of the vein’s lumen and to define their clinical significance.

The cervical regions of 93 cadavers, 186 sides in total, were dissected and the anatomical variations of internal jugular vein diameters in relation to the external jugular vein and to the common carotid artery were recorded and photographed.

The diameter of the veins in three cases were less than 6 mm, while ipsilateral external jugular veins were larger than average (3/93).

Anatomical variations of the internal jugular veins are clinically significant, especially in cases where venous access is important.

The aim of this study was to compare waste gas concentrations during xenon or nitrous oxide anaesthesia.

A total of 64 patients were included in this study. Gas concentrations were measured with a mass spectrometer during anaesthesia. The probes were taken beside the patient’s head and thorax and at a height of 180 cm above and at the floor level.

In both groups, waste gas concentrations peak after intubation and extubation. Waste gas levels during xenon anaesthesia are low compared with nitrous oxide.

The low waste gas levels of xenon seem to be beneficial compared to nitrous oxide.

For neuromuscular blocking agents, an inverse relationship between potency and time to peak effect has been observed. To test the hypothesis that this relationship is due to buffered diffusion, we investigated the influence of dose on time to peak effect. Pharmacokinetic–pharmacodynamic simulations were performed to support the expected relationships between potency, dose, peak effect and time to peak effect.

Pigs (20–28 kg body weight) were anaesthetized with ketamine and midazolam, followed by pentobarbital and fentanyl intravenously. Neuromuscular block was measured by stimulating the peroneal nerve supramaximally at 0.1 Hz and measuring the response of the tibialis anterior muscle mechanomyographically. After an initial dose to establish the individual ED90 of a neuromuscular blocking agent (rocuronium, vecuronium, pipecuronium or d-tubocurarine), five different doses of the same compound were administered to each animal, aiming at 20%, 40%, 60%, 75% or 90% block, in a random order. Doses were given 45 min after complete recovery of the twitch response.

For rocuronium and pipecuronium, time to peak effect increased with dose, whereas dose did not affect time to peak effect of vecuronium and d-tubocurarine. Simulations predict that time to peak effect decreases with dose if buffered diffusion is taken into account.

The results suggest that buffered diffusion does not play a dominant role in the time to peak effect of neuromuscular blocking agents. Therefore it is unlikely that the observed inverse relationship between potency and time to peak effect of neuromuscular blocking agents in the clinical range is due to buffered diffusion.

It has been demonstrated that volatile anaesthetics have cardioprotective properties during open-heart procedures, especially when administered continuously. European Council Directive 93/42/EEC concerning medical devices bans the supplementary incorporation of anaesthetic vaporizers in the bypass circuit. Since the uptake of volatile anaesthetics via diffusion membrane oxygenators is severely reduced, it is hypothesized that clinically relevant concentrations of sevoflurane will remain in the patients’ blood following saturation with a volatile agent before start of cardiopulmonary bypass. This study was designed to compare conventional and diffusion membrane oxygenators regarding their in vivo elimination of sevoflurane.

Twenty patients undergoing elective coronary bypass surgery were randomly allocated to two groups, either using a conventional polypropylene membrane oxygenator or a plasma-tight poly-(4-methyl-1-pentene) membrane oxygenator in a miniaturized extracorporeal circuit. Anaesthesia was maintained with sevoflurane, which was stopped at the start of cardiopulmonary bypass. During cardiopulmonary bypass, sevoflurane concentration was measured in blood and in the exhausted gas from the oxygenator.

The elimination of sevoflurane, expressed as the relative blood concentration, was significantly increased in polypropylene membrane oxygenators compared to poly-(4-methyl-1-pentene) membrane oxygenators. This resulted in an approximately threefold higher sevoflurane blood concentration in the poly-(4-methyl-1-pentene) group over the course of cardiopulmonary bypass.

With the incorporation of a poly-(4-methyl-1-pentene) oxygenator in a miniaturized bypass circuit, relevant concentrations of a previously applied volatile agent can be maintained even without further supply throughout cardiopulmonary bypass. This might be an alternative approach to cardioprotection when sevoflurane cannot be administered through cardiopulmonary bypass.