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Biomedical subjects

E Schindler

Publications and source records attributed to E Schindler.

At least 73 records · Page 4Linked to original sources
PubMed1996

Can clonidine, enoximone, and enalaprilat help to protect the myocardium against ischaemia in cardiac surgery?

OBJECTIVE: To evaluate whether clonidine, enoximone, and enalaprilat reduce ischaemia-related myocardial cell damage in cardiac surgery. DESIGN: Prospective randomised controlled trial. SETTING: Clinical investigation in a cardiac anaesthesia department of a university hospital. PATIENTS: 88 consecutive patients undergoing coronary artery bypass surgery. INTERVENTIONS: After induction of anaesthesia patients continuously received the alpha 2 agonist clonidine (group 1, n = 22), the phosphodiesterase (PDE) III inhibitor enoximone (group 2, n = 22), the angiotensin converting enzyme (ACE) inhibitor enalaprilat (group 3, n = 22), or saline solution as placebo (control group, n = 22). The infusion was stopped immediately before the start of cardiopulmonary bypass. MAIN OUTCOME MEASURES: The ST segment was analysed and the activity of creatine kinase isoenzyme MB (CKMB), cardiac troponin T (TnT), and the BB isoenzyme of glycogen phosphorylase (GPBB) were measured before the start of infusion (baseline), after weaning from cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB, and on the morning of the first and third postoperative days. RESULTS: Biometric data and time of cross-clamping were not significantly different in the four groups. Changes in the ST segment indicating ischaemia were least common in the enalaprilat group (P < 0.05). Postoperatively, CKMB activity was significantly higher in the clonidine and the control groups. Both new markers of myocardial cell damage increased more after CPB and postoperatively in the control patients (TnT peak: (mean (SD)) 3.99 (0.35) microgram/1; GPBB peak: 82 (15) ng/ml) and the clonidine-treated group (TnT peak: 3.80 (0.3) microgram/1; GPBB peak: 85 (14) ng/ml). Enalaprilat-treated patients showed the smallest overall changes in standard (CKMB) and new serological markers of myocardial ischaemia (TnT peak: 0.71 (0.1) microgram/1; GPBB peak: 44 (14) ng/ml). CONCLUSIONS: In patients treated with enalaprilat before CPB, both new, more sensitive markers of ischaemic myocardial tissue damage increased significantly less than in an untreated control group. Those treated with enoximone also had lower plasma concentration of TnT and GPBB than the control group, whereas clonidine did not reduce the concentration of these markers of myocardial ischaemia. Pharmacological interventions, such as the continuous infusion of the ACE inhibitor enalaprilat, before start of CPB may help to protect the heart against ischaemia/reperfusion injury.

Adrenergic alpha-Agonists↗
PubMed1996

[Effects of sevoflurane on the area of the liver and spleen].

Recently, there has been increased interest in the preservation of hepatic function during anaesthesia and surgery. In common with other halogenated volatile anaesthetics, sevoflurane causes dose-related cardiovascular depression, which suggests that the blood flow of various organ systems is affected. This paper summarises some of the published work dealing with sevoflurane and alterations of splanchnic and hepatic blood flow to date, mostly from animal studies. However, the experience with this substance in human studies is small as yet, and previously investigated animal models are too different to compare to humans. The effort should be encouraged to study this new volatile anaesthetic in human subjects; if a parallel to isoflurane can be drawn, the impact of both substances on the hepatic circulation should be quite small. In Germany, the introduction of sevoflurane into clinical practice should be a reason to proceed with clinical investigations of this type.

Anesthetics, Inhalation↗
PubMed1996

[Changes in somatosensory evoked potentials after sevoflurane and isoflurane. A randomized phase III study].

Monitoring of somatosensory evoked potentials (SEP) is used to identify critical phases of cerebral ischaemia by means of characteristic changes in the signal patterns. A correct interpretation of the results is possible, however, only if the influence of drugs that act on the central nervous system is known. We were able to show that volatile anaesthetics have an impact on latencies and stimulus amplitudes. In this study, we examined the influence of sevoflurane as compared with isoflurane on the conduction of SEP by the median nerve at various concentrations. In addition, we determined how the addition of nitrous oxide (N2O) influenced the stimulus response of median-nerve SEP. Both isoflurane and sevoflurane caused a dose-dependent increase in latency of the primary cortical complex, while the influence on the cervical components of the SEP with respect to increased latency was only slight. No significant difference was found between both study groups. Under the influence of N2O, there were marked reductions in amplitude of the cortical stimulus response. Thus, it can be recommended that supplementation with N2O should be avoided in the presence of low initial amplitudes. Based on our results, the use of isoflurane and sevoflurane concentrations up to 1.0 MAC seems to be compatible with intraoperative monitoring of SEP.

Anesthetics, Inhalation↗
PubMed1995

The neuroradiologist's contribution to stereotactic neuro-radio-surgery.

This publication is literally the same paper (having the same title and image material) which was previously presented at the International Symposium on Stereotactic Neuro-Radio-Surgery (Vienna, October 1992). Any actual updating of the topic has been avoided for reasons of historical accuracy and in order to document the atmosphere of that symposium which was then dominated by the unfolding of a new technology of intracranial lesion treatment. The neuroradiologist's contribution to this modality of treatment has to be the imaging and localizing such lesions accurately, as well as advising colleagues who plan radiosurgery and warning them about possible pitfalls. If there is no close cooperation between radiosurgeons and neuroradiologists, or if neuroradiological assistance is even disregarded, radiosurgical activities may fail.

Brain Diseases↗
PubMed1995

Circulating adhesion molecules in cardiac operations: influence of high-dose aprotinin.

Cardiac operations using cardiopulmonary bypass (CPB) are associated with a systemic inflammatory response most likely attributable to the release of various inflammatory mediators and activation of complement or coagulation cascade. In addition, (circulating) adhesion molecules, such as endothelial leukocyte adhesion molecule (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1), appear to be of central importance in the CPB-related inflammatory process. In this situation, antiproteases, such as aprotinin, may help to prevent damage of endothelial integrity. In a prospective study, 40 consecutive patients undergoing elective cardiac operation were randomly divided into two groups (with 20 patients in each group): in group 1 "high-dose" aprotinin was used (2 million IU of aprotinin before CPB, 500,000 IU/h until end of operation, 2 million IU added to the prime) (with aprotinin), and in group 2 no aprotinin was given (without aprotinin). Circulating adhesion molecules (cICAM-1, cELAM-1, and cVCAM-1) were measured from arterial blood samples using ELISA after induction of anesthesia (baseline), during CPB, at the end of the operation, 5 hours after CPB, and on the first postoperative day. The two groups were comparable concerning their biometric profile and CPB data. Baseline values of circulating adhesion molecules were within normal range and similar in both groups. During CPB, hemodilution resulted in a decrease in all circulating adhesion molecules. On the first postoperative day, cICAM-1 (with aprotinin, 215 +/- 32 ng/mL; without aprotinin, 230 +/- 40 ng/mL) and cELAM-1 (with aprotinin, 28 +/- 6 ng/mL; without aprotinin, 31 +/- 6 ng/mL) returned to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

RETRACTED: Cardiorespiratory response of intravenous angiotensin-converting enzyme inhibitor enalaprilat in hypertensive cardiac surgery patients.

Twenty-four patients undergoing elective coronary artery bypass surgery were studied. Either the angiotensin-converting enzyme (ACE) inhibitor enalaprilat, 0.06 mg/kg, (n = 12), or saline solution (= control group; n = 12), was randomly and blindly administered intravenously when the mean arterial blood pressure (MAP) increased to 90 mmHg after induction of anesthesia. Cardiorespiratory parameters were studied before injection, during the subsequent 30 minutes, precardiopulmonary bypass (CPB), post-CPB, and at the end of surgery. MAP was significantly reduced 5 minutes after administration of enalaprilat. The peak reduction of blood pressure was observed after 30 minutes (from 98 +/- 4 to 68 +/- 8 mmHg). Even immediately before CPB (112 +/- 12 minutes after injection of enalaprilat), MAP and systemic vascular resistance were significantly lower than baseline values. Heart rate remained almost unchanged in both groups. Cardiac index increased slightly in the enalaprilat patients (maximum: +0.75 L/min/m2 20 minutes after injection). Filling pressures (central venous pressure, pulmonary capillary wedge pressure) were also significantly reduced by enalaprilat. There were no differences from the control patients with regard to changes in right ventricular hemodynamics (right ventricular ejection fraction, right ventricular end-diastolic volume, right ventricular end-systolic volume), pulmonary gas exchange (PaO2), or intrapulmonary right-to-left shunting (Qs/Qt). VO2 increased only in the enalaprilat patients (from 179 +/- 28 to 230 +/- 30 mL/min) (p < 0.05). Cardiorespiratory parameters did not differ between the two groups post-CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1995

Endothelial-related coagulation in cardiac surgery.

The endothelium appears to play an important role in the regulation of intravascular coagulation. Thrombomodulin is one of the anticoagulant substances that is expressed by endothelial cells. The influence of age and illness on the thrombomodulin-protein C system was studied prospectively in 80 cardiac surgery patients. Patients > 70 yr old (n = 20) were compared with patients < 50 yr (n = 20) (group I), and patients undergoing a simple cardiac procedure (n = 20) were compared with patients scheduled for complex surgery (n = 20) (group II). Thrombomodulin (normal < 40 ng ml-1), protein C and (free) protein S plasma concentrations were measured by enzyme-linked immunosorbent assays (ELISA) after induction of anaesthesia (baseline values), during and after cardiopulmonary bypass (CPB), at the end of surgery, 5 h after CPB and on the first day after operation. Blood loss and use of homologous blood and blood products were significantly greater in patients > 70 yr and in those undergoing complex surgery. At baseline, thrombomodulin concentration was increased in patients undergoing complex surgery (mean 52 (sd 9) ng ml-1). After bypass and after operation, thrombomodulin increased most in patients > 70 yr (from 40 (8) to 78 (10) ng ml-1) and in those patients who underwent complex cardiac operations (from 52 (8) to 79 (10 ng ml-1) (P < 0.05). Changes in protein C and protein S concentrations were similar in all groups. On the first day after operation only, protein C concentrations were reduced in patients > 70 yr and in patients who underwent complex cardiac surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Influence of intravenous administration of angiotensin-converting enzyme inhibitor enalaprilat on cardiovascular mediators in cardiac surgery patients.

The renin-angiotensin system (RAS) is important in controlling and maintaining cardiovascular homeostasis. In a randomized, prospective study, the response to intravenous (i.v.) administration of the angiotensin-converting enzyme (ACE) inhibitor enalaprilat (0.06 mg/kg) on important controllers of the circulation was investigated in 14 patients undergoing aortocoronary bypass grafting with a mean arterial blood pressure (MAP) > 85 mm Hg after induction of anesthesia. Fourteen patients received saline solution as placebo (control group). Endothelin (ET), atrial natriuretic peptide (ANP), catecholamine (epinephrine, norepinephrine) plasma levels, and ACE activity were measured from arterial blood sampled before injection of enalaprilat or NaCl solution (baseline values), 10 min and 30 min thereafter, immediately before the start of cardiopulmonary bypass (CPB), immediately after CPB, and at the end of surgery. MAP, heart rate (HR), cardiac index (CI), and systemic vascular resistance (SVR) were also monitored. ACE activity was similar at baseline in both groups; after i.v. injection of enalaprilat, it significantly decreased (from 35.1 +/- 11 to 4.4 +/- 1.0 U.min-1.L-1 30 min after injection) and remained reduced until the end of the operation (295 +/- 31 min after injection). ANP plasma levels were increased beyond normal (> 100 pg/mL) at baseline in both groups. They increased significantly in the control patients, but remained almost unchanged in the enalaprilat-treated patients within the entire study period. Plasma concentration of ET also increased only in the control group and was increased after CPB (8.6 +/- 1.2 pg/mL at the end of the operation).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

The effect of the anticoagulation regimen on endothelial-related coagulation in cardiac surgery patients.

Heparin is still the most commonly used anticoagulant in cardiac surgery necessitating cardiopulmonary bypass. In recent years, endothelial-related coagulation (e.g. thrombomodulin/protein C-system) has enlarged our knowledge of the regulation of haemostasis. In a controlled randomised study, the influence of different regimens of anticoagulation on the thrombomodulin/protein C-system was studied. Sixty patients undergoing elective coronary artery bypass grafting were randomly allocated into four groups (n = 15) to receive: 300 IU.kg-1 of heparin before bypass; 600 IU.kg-1 of heparin; 300 IU.kg-1 of heparin as bolus followed by a continuous infusion of 10 000 IU.h-1 until the end of bypass; or 600 IU.kg-1 of heparin plus 'high dose' aprotinin (2 million IU of aprotinin before bypass, 500 000 IU.h-1 until the end of the operation and 2 million IU added to the bypass pump prime). Grouping was blinded for the surgeon and the anaesthetist. Plasma concentrations of thrombomodulin, protein C and (free) protein S as well as thrombin/antithrombin III were measured by enzyme-linked-immunosorbent assays after induction of anaesthesia, during and after bypass, at the end of surgery, 5 h after bypass, and on the first postoperative day. Activated clotting time was significantly longer during bypass in group 2 (566 (60)s) and group 4 (655 (59)s), whereas standard coagulation parameters showed no differences between the four groups. Blood loss and use of homologous blood and blood products were highest in groups 2 and 3. Thrombomodulin plasma levels were similar (and normal) at baseline (< 40 ng.l-1), decreased during bypass and reached baseline values postoperatively without showing significant group differences. Protein C did not show any differences among the groups within the investigation period. 'Free' protein S plasma levels were most reduced in group 1 (from 68 (8)% to 48 (9)% after bypass). Thrombin/antithrombin III plasma concentrations increased most in groups 1 (to 69 (14) micrograms.l-1 after bypass) and 2 (to 48 (7) micrograms.l-1 after bypass), whereas they remained significantly lower in groups 3 and 4. The thrombomodulin/protein C-system was not significantly influenced by the regimen of anticoagulation. Administration of 'high-dose' heparin was associated with the highest blood loss, which could not be related to endothelial-associated coagulation.

Aged↗
PubMed1995

[Cerebral oximetry by infrared spectroscopy in comparison with continuous measurement of oxygen saturation of the jugular vein bulb in interventions of the internal carotid artery].

OBJECTIVE: Monitoring the central nervous system during carotid endarterectomy plays an important role in detection of cerebral ischemia. With optical spectroscopy in the near-infrared light range it is now possible to measure regional cerebral oxygen saturation (rSO2) noninvasively. Numerous studies emphasize the importance of cerebral oxygen balance rather than absolute values of cerebral blood flow or metabolic rate. In this study data from oxygen saturation measured in the jugular bulb (SJO2) were compared to rSO2. METHODS: 10 patients undergoing elective carotid end-arterectomy were enrolled after written informed consent and approval by the local ethics committee. rSO2 data were measured by cerebral spectroscopy (INVOS 3100, Somanetics, Michigan/USA). To avoid lesions of the internal carotid artery, a 4-F oxymetry catheter (OPTICATH, Abbot GmbH, Wiesbaden) was placed in the jugular bulb by retrograde approach after preparation by the surgeon. Anaesthesia and mechanical ventilation were standardised. RESULTS: After cross-clamping of the internal carotid artery rSO2 significantly decreased (60.5 +/- 3.5%) compared to baseline (66.0 +/- 1.4%). After declamping rSO2 increased significantly (63.0 +/- 4.2%) and was close to baseline at the end of operation (65.0 +/- 2.8%). The SJO2 time course showed good correlation compared to rSO2 data (r = 0.85). After cross-clamping SJO2 decreased significantly (51.5 +/- 6.3%) in comparison to baseline (59.5 +/- 4.9%). Declamping increased SJO2 to 59.5 +/- 6.3%. No changes in latencies or amplitudes of SEP were observed throughout the operation. CONCLUSIONS: Noninvasive cerebral optical spectroscopy is a useful tool to determine the brain tissue oxygenation. The positive correlation to jugular bulb oxygen saturation is somewhat unexpected as rSO2 evaluates regional while SJO2 measures global oxygen content. However our results suggests that both methods are able to detect episodes of cerebral ischemia during carotid endarterectomy. The interpretation of the changes of cerebral oxygen saturation with respect to neurological outcome warrants further studies.

Aged↗
PubMed1994

Magnetic resonance angiography and selective angiography following extra-intracranial bypass operations.

Magnetic resonance angiography (MRA) was compared with conventional angiography in 14 patients following extra-intracranial arterial anastomosis. In 13 patients the bypass was shown by MRA and confirmed by conventional angiography. In five of these, the anastomosed vessels, in particular the superficial temporal artery, was of the same calibre or smaller than the same vessels on the contralateral, healthy side. In one patient no anastomosis could be shown by MRA, and occlusion of the bypass was confirmed by conventional angiography. Absence of dilatation of the anastomotic vessels may indicate insufficient bypass function due to stenosis or an incorrect indication for surgery.

Adult↗
PubMed1994

Thrombomodulin in pediatric cardiac surgery.

In 30 consecutive children with congenital heart disease scheduled for pediatric cardiac operations, thrombomodulin, protein C, free protein S, and thrombin-antithrombin complex were measured by enzyme-linked immunosorbent assay after the induction of anesthesia (baseline value), and then before, during, and after cardiopulmonary bypass until the first postoperative day. The patients were divided prospectively into two groups: children weighing less than 10 kg (group 1; n = 15) and those weighing more than 10 kg (group 2; n = 15). At baseline, the plasma concentration of thrombomodulin was significantly higher in the children in group 1 than in those in group 2 (83.1 +/- 11.0 ng/mL versus 29.2 +/- 12.1 ng/mL). During cardiopulmonary bypass, the thrombomodulin level was reduced in both groups without showing any significant group differences. Five hours after cardiopulmonary bypass and on the first postoperative day, the thrombomodulin level exceeded normal values only in the children weighing less than 10 kg. In both groups, the protein C levels were already below normal at the beginning of the study. The baseline protein S concentration was higher in the smaller children (80% +/- 18%) than in the larger children (66% +/- 11%). It was reduced by cardiopulmonary bypass in both groups; however, postoperatively it did not return to normal in group 1 (45.1% +/- 10%). Plasma levels of the thrombin-antithrombin complex were similar in both groups, with a marked increase at the end of cardiopulmonary bypass, and returned to near-normal levels by 5 hours after bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1994

RETRACTED: Does aprotinin influence endothelial-associated coagulation in cardiac surgery?

Aprotinin has been reported to reduce bleeding in cardiac surgery patients. Its mechanisms of action on coagulation have not been fully elucidated. In a prospectively randomized study of 40 patients undergoing elective aortocoronary bypass grafting, the influence of high-dose aprotinin (2 million IU of aprotinin before CPB, 500,000 IU/h until the end of operation, 2 million IU added to the prime) (N = 20) on endothelial-related coagulation was compared to a nontreated control group (N = 20). Thrombomodulin (TM), protein C and (free) protein S as well as thrombin/antithrombin-III (TAT) plasma concentrations were measured by enzyme-linked immunosorbent assays (ELISA) before the aprotinin infusion, before cardiopulmonary bypass (CPB), during CPB and after CPB, at the end of surgery, 5 hours after CPB, and on the first postoperative day. All standard coagulation parameters (AT-III and fibrinogen plasma levels, platelet count, partial thromboplastin time) did not differ between the two groups. At baseline, TM plasma levels were within the normal range (< 40 ng/mL) and similar in both groups. During CPB, TM plasma concentrations decreased similarly in both groups (aprotinin: 18 +/- 6 ng/mL, control: 17 +/- 7 ng/mL) followed by a comparable increase in the postbypass period until the first postoperative day (aprotinin: 60 +/- 10 ng/mL, control: 53 +/- 11 ng/mL). Protein C and (free) protein S plasma levels also showed no differences between the two groups. On the first postoperative day, baseline values for protein C and protein S had not yet been reached.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1994

Influence of different anticoagulation regimens on platelet function during cardiac surgery.

Qualitative platelet defects are of great importance as a cause of bleeding in cardiac surgery. We have studied the effects of different anticoagulation regimens on platelet function in 60 patients undergoing elective aorto-coronary bypass grafting with cardiopulmonary bypass (CPB). Patients were allocated randomly to four groups (each group n = 15) to receive either: bovine heparin 300 u. kg-1 (standard); heparin 300 u. kg-1 followed by a continuous infusion of 10,000 u. kg-1 until the end of CPB; heparin 600 u. kg-1; or heparin 600 u. kg-1 in addition to high-dose aprotinin 2 million iu before CPB, 500,000 iu h-1 until the end of operation and 2 million iu added to the prime. Platelet function was evaluated by aggregometry (turbidometric technique) using adenosine triphosphate (ADP) 2.0 mumol litre-1, collagen 4 microliters ml-1, adrenaline 25 mumol litre-1 and saline solution (control) as inducers. Both maximum aggregation and maximum gradient of aggregation were measured in arterial blood samples before, during and after CPB until the first day after operation. Mean total dose of heparin given in groups 2, 3 and 4 was more than 50,000 u. and differed significantly from that of group 1 (28,150 (SD 4700)u.). Platelet aggregation variables were most depressed during CPB and until the end of surgery in groups 2 and 3 (maximum aggregation - 54% to - 75% of baseline values). In the postoperative period, platelet function recovered but did not completely reach baseline values in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Functional imaging of effects of fragrances on the human brain after prolonged inhalation.

Beside olfactory or trigeminal stimulation of chemosensory receptor-cells some results in published literature suggest that fragrances show a direct affect on the brain. The effect of the fragrance 1,8-cineol, which was described in literature as 'stimulating', on regional and global cerebral blood flow (rCBF and gCBF) in the human brain after prolonged inhalation was investigated. The results show an increase of global-CBF without preference to primary or secondary olfactory centres after an inhalation-time of 20 min.

Adult↗
PubMed1994

Influence of aprotinin on the thrombomodulin/protein C system in pediatric cardiac operations.

Thirty consecutive children scheduled for pediatric cardiac operation with cardiopulmonary bypass were included in the study. Before the operation, the patients were randomly divided into two groups: with aprotinin (n = 15, 30,000 U/kg after induction of anesthesia, 30,000 U/kg added to the prime of the cardiopulmonary bypass or without aprotinin (n = 15). Thrombomodulin, (free) protein S, protein C, and thrombin/antithrombin III complex were measured from arterial blood samples taken after induction of anesthesia (at baseline, before aprotinin) and before, during, and after cardiopulmonary bypass until the first postoperative day. Standard coagulation parameters (antithrombin III, fibrinogen, platelet count, and partial thromboplastin time) were without differences between the groups. Thrombomodulin plasma concentrations were within normal range ( < 40 micrograms/L) and were similar in both groups at baseline. During cardiopulmonary bypass and until 5 hours after cardiopulmonary bypass, however, thrombomodulin plasma levels were significantly lower in the children treated with aprotinin. No further differences were observed on the first postoperative day. Protein C and protein S plasma levels did not differ between the two groups. Thrombin/antithrombin III-complex plasma concentrations increased significantly during cardiopulmonary bypass, however, without showing differences between children with (225 +/- 49 micrograms/L) and without (149 +/- 31 micrograms/L) aprotinin treatment. Blood loss and the need for homologous blood and blood products did not differ significantly between the two groups. We concluded that administration of aprotinin resulted in reduced thrombomodulin plasma levels in pediatric patients undergoing cardiac operation without altering protein C/protein S plasma concentration. The exact role of aprotinin in endothelium-derived coagulation should be further studied.

Antithrombin III↗
PubMed1994

[Topographic electroencephalometry following anesthesia induction with ketamine-midazolam].

The neurophysiological action of ketamine has attracted increasing interest in recent years, with special interest in receptor action and in neurophysiological differences between and psychomimetic side effects of the two enantiomorphs. Most of the neurophysiological examinations published deal with ketamine as a single anaesthetic agent, although it has been suggested to that psychomimetic side-effects and haemodynamic deterioration could be avoided by combining ketamine with a sedative drug. The primary aim of our study was to examine the combined ketamine-midazolam action on cerebral activity; secondly, we planned to look at these interactions topographically at different points of the cortex to evaluate topographical differences in the combination's action; thirdly, the cerebral and haemodynamic reactions to anaesthesiological stimuli (intubation, gastric tube) were evaluated and compared. METHODS. Sixteen patients scheduled for elective aortocoronary bypass surgery were examined. Topographical electroencephalometric data were obtained by processed EEG with a CATEEM system at 17 recording points over the cortex and compared with heart rate and arterial blood pressure during the induction period. After documentation of the baseline data ketamine (3 mg/kg) and midazolam (0.15 mg/kg) were applied within 10 min by means of an automatic device. At the end of the infusion period patients were intubated, and after a further 10 min a gastric tube was placed. RESULTS. Induction resulted in increases in delta and beta 2 output (P < 0.05) in the early induction period and in significant decreases (P < 0.05) in alpha 1, alpha 2 and beta 1 activity. No significant change in theta activity was observed throughout the observation period. Intubation led to significant increases of power particularly in the temporal and parietal leads of all frequency bands, but not in the frontal area. Insertion of the gastric tube did not alter cerebral function. CONCLUSION. The interaction of ketamine and midazolam leads to increases in beta 2 and delta power and to significant decreases in the alpha bands and beta 1. Increases of theta activity, a typical effect of single-agent anaesthesia with ketamine, were not observed. Thus, the action of combined ketamine and midazolam on cerebral function is not an additive, but an interactive process. Despite a relatively high induction dosage, haemodynamic changes during intubation occurred and were accompanied by changes in cerebral activity. This can be regarded as incomplete cerebral suppression even by these induction dosages.

Adult↗