SummaryThe haemodynamic eflects of propofol (2 mglkg), etomidate (0.2 mglkg) and thiopentone ( 4 mglkg) were studied in 30 ASA 1 and 2 patients in whom anaesthesia had been induced with midazolam 0.1 mglkg, fentanyl5 pglkg, vecuronium 0.1 mglkg and atropine 10 pglkg, and maintained with nitrous oxide in oxygen. Arterial pressure was measured directly and left ventricular diameters were determined by transoesophageal echocardiography. Systolic blood pressure after propofol and thiopentone and the end-systolic quotient (systolic pressurelend-systolic diameter), a measure of inotropy, decreased. Fractional shortening ( end-diastolic -end-systolic diameterlend-diastolic diameter) decreased only in the thiopentone group, Diastolic blood pressure and end-diastolic diameter ( a measure of preload) did not change in any of the groups, and the etomidate group showed no changes in the haemodynamic variables measured. Propofol shows simultaneous negative inotropy and afterload reduction, while thiopentone is exclusively negatively inotropic. Key wordsAnaesthetics, intravenous; propofol, thiopentone, etomidate. Measurement techniques; transoesophageal echocardiography, electroencephalography.Many studies have reported a reduction in arterial blood pressure after injection of the intravenous anaesthetic agent propofol. Reductions in blood pressure were more marked, and hypotensive reactions more frequent after propofol in comparison with etomidate' and thio~entone?~ but there is still no consensus in the literature why these reductions occur, be they negative inotropy, afterload reduction or both.Almost all the patient studies to date, which were based on load-dependent variables, have differentiated poorly between the inotropic effects of propofol and its influence on myocardial loading factors.The aim of our study was to demonstrate whether the decrease in arterial blood pressure after propofol is from negative inotropy and (or) changes in myocardial loading (prelafterload), using a method considered to be relatively insensitive to load factors: namely inotropy measurements by transoesophageal echocardiography (TEE). In addition, we compared the haemodynamic effects of propofol with those of thiopentone and etomidate. MethodsThirty normotensive surgical or orthopaedic patients in ASA groups 1 and 2 were placed at random into either a propofol (n = lo), thiopentone (n = 10) or etomidate (n = 10) group. None of the patients was receiving any concomitant cardiovascular medication, and all gave written informed consent to the study; the study itself was approved by the Ethics committee of the University of Ulm.Each patient received orally 20 mg clorazepam as premedication one hour before the study. We injected atropine 10 pg/kg intravenously 5 minutes before induction, which was with midazolam 0.1 mg/kg and fentanyl 5 pg/kg. Vecuronium 0.1 mg/kg was given to facilitate tracheal intubation. Anaesthesia was continued after tracheal intubation, with controlled ventilation with N,O:O, (no, = 0.3) to normocapnia (PE'co, = 4.6-6.0 k...

The effect of high thoracic epidural anesthesia (TEA on left ventricular contractility was studied in a prospective clinical trial. Forty-eight patients with ASA physical status 1 and 2 and without cardiovascular disease were included in the study. Thirty-six patients scheduled for elective upper abdominal surgery were randomly assigned to Group 1 (TEA, bupivacaine 0.25%, n = 12), Group 2 (TEA, bupivacaine 0.5%, n = 12) or to Group 3 (control without TEA, n = 12). TEA induced a sensory block which extended over all cardiac segments. In order to assess the effect of systemically absorbed bupivacaine, we studied a separate group of patients who received lumbar epidural anesthesia without involvement of the cardiac segments: Group 4 (LEA, bupivacaine 0.5%, n = 10). Left ventricular contractility was assessed using the end-systolic pressure-length relationship. Left ventricular dimensions were measured by transesophageal echocardiography. All hemodynamic measurements were performed under general anesthesia. There was no significant difference in systolic or diastolic arterial pressure, heart rate, left ventricular end-systolic and end-diastolic cross-sectional areas and left ventricular wall stress between the four groups. Left ventricular maximum elastance as a measure of left ventricular contractility was significantly (P < 0.001) reduced in Groups 1 and 2 [8.1 (+/- 3.5) and 9.6 (+/- 4.4) kPa.cm-1, respectively] as compared to Groups 3 and 4 [18.4 (+/- 8.8) and 17.7 (+/- 7.7) kPa.cm-1, respectively]. No significant difference could be demonstrated between Groups 1 and 2 or between Groups 3 and 4. It is concluded that high TEA severely alters left ventricular contractility even in subjects without pre-existing cardiac disease.

SummaryBaroreflex control of heart rate after cardiac sympathectomy induced by thoracic epidural anaesthesia was evaluated in 30 patients who were randomly assigned to group I (bupivacaine 0.25%). group 2 (bupivacaine 0.5%) or group 3 (control). Plasma volume expanders were given to equalise preload conditions. as assessed using transoesophageal echocardiography. All measurements were made under general anaesthesia. Barorejex sensitivity was determined from the heart rate response to phenylephrine and nitroglycerine. There was no difference in cardiac slowing in response to phenylephrine hetween the three groups. Baroreflex sensitivity. measured as cardiac acceleration in response to nitroglycerine, was significantly lower ( p < 0.01) in groups I and 2 (1.8 and 1.5 ms.mmHg-' respectively) compared with group 3 (3.5 ms.mmHg-') with no differences between the two hupivacaine concentrations. The results suggest that barorejex-mediated response to decreases in arteriul pressure is dependent on the integrity of the sympathetic nervous system. Key wordsAnaesthetic techniques regional; epidural. Reflexes; baroreceptor. Heart; cardiovascular reflexes. Sympatheric nervous system; blockade.It has been suggested that cardiac sympathectomy induced by high spinal or epidural anaesthesia may alter arterial baroreceptor reflexes [ 1-31, At present, little information is available about the extent and clinical significance of such alterations. One study by Takeshima and Dohi surprisingly showed that cardiac sympathectomy induced by cervical epidural blockade did not alter heart rate response to decreasing blood pressure, but suppressed cardiac slowing in response to blood pressure increase [4]. It was speculated that sympathetic control of heart rate might function as a vagus inhibitor rather than as an active cardiac accelerator. The authors admitted that cardiopulmonary baroreceptors could have been affected by changes in central blood volume, secondary to peripheral vasodilation or vasoconstruction, and that this might have altered arterial baroreceptor heart rate reflex.The aim of our study was to investigate the effect of high thoracic epidural anaesthesia on baroreflex control of heart rate, in a controlled randomised trial, with an attempt to keep central blood volume equal in the different groups. Secondly, we compared the effect of two different bupivacaine concentrations (0.25% and 0.5%) on the baroreflex control of heart rate. MethodsThirty patients, with an ASA physical status of 1 or 2, scheduled for elective abdominal surgery entered the study. Subjects with any kind of cardiac or circulatory disorder, autonomic neuropathy, contraindications to epidural anaesthesia and contraindications to transoesophageal echocardiography were not studied. The abdominal operations included: duodenum-preserving resection of the pancreatic head (n = 12), cholecystectomy ( n = 6), cholecystojejunostomy ( n = 4), liver tumour resection ( n = 2), Whipple's pancreaticoduodenectomy (n = 2), resection of the sigmoid colon (n = I), cholec...

A number of studies in medical literature suggest that during implantation of hip prostheses pulmonary embolism of medullary contents and of air may occur. Proof of this suggestion was based on histological examination of lung tissue in animal experiments as well as on post mortem examinations of human tissue. In vivo evidence of this suspected embolism has been lacking so far, since an appropriate technique has not been available. Using transesophageal two-dimensional echocardiography, continuous imaging of the right atrium and the right ventricle can be performed in order to prove this suspected embolization in vivo. Thus, in a prospective randomized study of 26 patients undergoing hip surgery, the right atrium and right ventricle were continuously imaged. Simultaneously, the end-expiratory CO2 partial pressure was recorded. The medical literature suggests that a venting hole in the shaft of the femur prevents the rise in pressure in the medullary space and thus also averts embolism. Therefore, prior to the implantation of the shaft prosthesis, and in order to vent the medullary space, in 13 patients a 4.5-mm lateral borehole was drilled into the femoral shaft, located two finger breadths distal to the point were the end of the prosthesis would be positioned. In 12 of 13 patients in the control group without boreholes, transesophageal two-dimensional echocardiography revealed that air bubbles formed during the implantation of the shaft. In the group with boreholes, however, presence of air could be demonstrated in only four patients (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)