Effects of systemically applied clonidine on intestinal perfusion and oxygenation in healthy pigs during general anaesthesia and laparotomy

BACKGROUND AND OBJECTIVE: Clonidine, which is used for induction of sympatholysis and prevention or treatment of alcohol withdrawal in anaesthesia and intensive care medicine, may have deleterious effects on intestinal mucosal perfusion. This study was designed to investigate the effects of clonidine on intestinal perfusion and oxygenation. METHODS: Following ethical approval 17 anaesthetized, and acutely instrumented pigs were randomly assigned to two groups: eight animals received intravenous clonidine (2 microg kg(-1) bolus and 2 microg kg(-1) h(-1)), nine animals served as a control group. Measurement points for systemic and regional haemodynamic and oxygenation parameters were 135 and 315 min after starting the clonidine application. RESULTS: Clonidine elicited systemic haemodynamic changes (median [25-75th interquartile range]): heart rate (106 [91, 126] to 84 [71, 90] beats min(-1)) cardiac output (147 [123, 193] to 90 [87, 107] mL min(-1) kg(-1)) and mean arterial pressure (77 [72, 93] to 69 [61, 78] mmHg) decreased. Despite systemic haemodynamic changes, the superior mesenteric artery blood flow did not change in the clonidine group. The vascular resistance of the superior mesenteric artery decreased. The small intestinal oxygen supply, the mucosal and the serosal tissue oxygen partial pressure did not change. CONCLUSIONS: Systemic sympatholysis induced by intravenously applied clonidine in addition to basic intravenous anaesthesia elicited a decrease in cardiac output and mean arterial pressure. However, regional macrohaemodynamic perfusion was maintained and intestinal oxygenation did not change. Clonidine does not impair intestinal mucosal and serosal oxygenation under physiological conditions.     

Aortofemoral bifurcation bypass--effect of the anesthesia procedure (NLA, thoracic continuous catheter peridural anesthesia) on circulation, respiration and metabolism. Intraoperative circulatory reactions

51 patients who were selected for aorto-bifemoral bypass operation (infrarenal aortic aneurysm, iliac or iliofemoral occlusive disease) were randomized into two groups. 26 patients were operated on under neuroleptanaesthesia and 25 patients had a continuous thoracic epidural, which was supplemented with a light general anaesthesia during the operation. All patients were optimally volume loaded prior to surgery. The most marked haemodynamic alterations (tachycardia, arterial hypertension, increase of cardiac index, left ventricular stroke work index and cardiac minute work) were provoked by eventration of the gut. In the epidural group, these changes were attenuated and in contrast to the neuroleptanaesthesia group, there were a few patients who had a serious fall in blood pressure. These reactions were regularly accompanied by a generalized flush which led to the hypothesis that they were caused by the release of intestinal hormones, reactive peptides and neurotransmitters, from the mechanically irritated gut. Clamping of the aorta was relatively uneventful. Heart rate and cardiac index decreased in both groups but mean arterial pressure and pulmonary capillary wedge pressure remained stable. Systemic vascular resistance increased slightly in the neuroleptanaesthesia, but not in the epidural group. Declamping was followed by significant but transient falls in systemic vascular resistance and arterial pressure in both groups, despite sufficient volume loading before opening the clamp. In the neuroleptanaesthesia group these changes spontaneously returned to normal; in the epidural group 6 patients received vasopressors or positive inotropic drugs. These results indicate the following: Epidural anaesthesia prevents hypertension and tachycardia and lowers cardiac minute work. Eventration of the gut, acute blood losses and declamping of the aorta may be critical situations, which can lead to profound hypotension. Under neuroleptanaesthesia eventration of the gut is followed by tachycardia and hypertension whereas blood losses and declamping are not as critical as when an epidural is used. Only experienced anaesthetists should use epidural anaesthesia for aortic surgery. An intensive monitoring of haemodynamic function during this form of anaesthesia is mandatory.     

The effect of anaesthesia and aortic clamping on cardiac output measurement using arterial pulse power analysis during aortic aneurysm repair

The LiDCO plus monitor (LiDCO Ltd, Cambridge, UK) uses pulse contour analysis of the arterial pressure waveform to indicate changes in stroke volume and cardiac output. Calibration against a lithium indicator dilution method is required to permit display of absolute values in addition to trends. The effect of haemodynamic changes during anaesthesia and surgery on this calibration factor has not previously been studied. Therefore, we investigated whether it remained constant during elective abdominal aortic aneurysm surgery in 15 patients. Comparison between the calibration factor values at different time points was made by repeated recalibration throughout the peri-operative period. Calibration factor increased by a mean of 53% after anaesthesia (epidural plus general) (p = 0.03) and decreased by a mean of 40% after aortic clamping (p = 0.0001). Recalibration should be undertaken after induction of anaesthesia and after aortic clamping if absolute values of cardiac output and stroke volume are required.     

Are diabetic patients in danger at renal transplantation? An invasive perioperative study

It is assumed that diabetic patients with uraemia have more complications at renal transplantation than those who are not diabetic. We compared the preoperative ECGs, and invasive perioperative haemodynamic and oxygenation parameters in 15 diabetic and 15 non-diabetic uraemic patients undergoing renal transplantation. The number of patients with increased QT dispersion in the ECG was higher in diabetic than in non-diabetic patients (P<0.05). Before anaesthesia, heart rate and mean arterial pressure were higher (P<0.05) in the diabetic than in the non-diabetic group. After preanaesthetic volume loading all patients showed a hyperdynamic circulation, which subsided during anaesthesia. However, stroke volume index remained unchanged. Four patients in the diabetic group and six in the non-diabetic group needed additional oxygen therapy after surgery. No cardiac dysrhythmias were noted. However, the increased QT dispersion in diabetic patients calls for an adequate perioperative ECG monitoring for dysrhythmias. The diabetic and non-diabetic uraemic patients performed equally well at renal transplantation. In conclusion, renal transplantation for diabetics is justified.     

Detection of volume loss using the Nexfin device in blood donors

We investigated which haemodynamic parameters derived from Nexfin non‐invasive continuous arterial blood pressure measurements are optimal to detect controlled volume loss in spontaneously breathing subjects. Haemodynamic monitoring was performed in 40 whole‐blood donors. Mean arterial pressure, cardiac index, systemic vascular resistance index and pulse pressure variation were recorded during controlled breathing, and a Valsalva manoeuvre was performed before and after blood donation. Blood donation resulted in a reduction in cardiac index (from 3.96 ± 0.84 l.min^?1.m² to 3.30 ± 0.61 l.min^?1.m²; p < 0.001), an increase in systemic vascular resistance (from 1811 ± 450 dyn.s.cm^?5.m² to 2137 ± 428 dyn.s.cm^?5.m²; p < 0.001) and an increase in pulse pressure variation (from 13.4 ± 5.1 to 15.3 ± 5.4%; p = 0.02). The area under the receiver operating characteristic curve to detect volume loss was highest for cardiac index (0.94, 95% CI 0.88–0.99) and systemic vascular resistance (0.90, 95% CI 0.82–0.99). Nexfin is a non‐invasive haemodynamic monitor that can feasibly detect volaemic changes in spontaneously breathing subjects.     

Epidural vs general anaesthesia and leg blood flow in patients with occlusive atherosclerotic disease

Total leg blood flow (plethysmography), skin blood flow (laser-Doppler flowmetry), and haemodynamic stability (MAP, HR, RPP) were studied in vascular (ABI less than 1.0; n = 31) and in non-vascular (ABI greater than 1.0; n = 24) surgical patients during epidural or fentanyl-supplemented general anaesthesia. During epidural anaesthesia significant increases in total leg blood flow were observed in vascular (from 1.9 +/- 0.2 to about 3 ml/100 ml tissue/min) as well as in non-vascular (from 2.5 +/- 0.6 to about 7 ml/100 ml tissue/min) patients and leg blood flow remained high in the postanaesthetic period. During general anaesthesia total leg blood did not increase, either in vascular or in non-vascular patients, and in the postanaesthetic period blood flow values even lower than the initial ones were observed. Skin blood flow increased about 4-fold in vascular as well as in non-vascular patients following both types of anaesthesia. In the immediate postanaesthetic period low flow values were again observed but only in the general anaesthesia groups. In vascular patients no critical redistribution of blood flow within the limb was observed irrespective of the type of anaesthesia. Good haemodynamic stability could only be maintained in the epidural group. It is concluded that epidural anaesthesia seems to offer considerable advantages over general anaesthesia for high-risk vascular patients during arterial reconstructions since better haemodynamic stability and higher leg blood flow can be achieved.     

Use of impedance cardiography to monitor haemodynamic changes during laparoscopy in children

METHODS: Haemodynamic changes were measured noninvasively using impedance cardiography (ICG) in 30 ASA I children during laparoscopic varicocelectomy under general anaesthesia. After induction and intubation, mechanical ventilation was started, then pneumoperitoneum (PP) was created. During the course of anaesthesia, values of endtidal CO2 pressue (PECO2), peak inspiratory airway pressure (PIP), heart rate (HR), mean arterial blood pressure (MABP), stroke volume index (SVI), cardiac index (CI) and systemic vascular resistance index (SVRI) were recorded at 1 min intervals. We analysed four periods: T1, before induction; T2, after induction; T3, during PP; T4, after desufflation of PP until awake. RESULTS: After induction of anaesthesia a significant reduction of HR, MABP and CI was recorded. Creating PP together with the use of a 15 degrees head down tilt resulted in a further drop in CI, mainly caused by the reduction of SVI, and an elevation of MABP and SVRI. We measured a 25% total decrease of CI. CONCLUSION: Our patients tolerated this significant reduction of cardiac output well. We have demonstrated that ICG can be used to track the haemodynamic changes caused by PP in children, and suggest that this type of monitoring is useful in this group of age during laparoscopy.     

The Haemodynamic Effects of Dopamine and Prenalterol in Patients after Cardiac Valve Surgery

The haemodynamic effects of prenalterol and dopamine were compared in 10 patients about 4 h after cardiac valve replacement during a phase of temporarily depressed myocardial function. The rate of infusion was adjusted to give similar increases in stroke volume with the two drugs (dopamine +17 % and prenalterol +18%). Both drugs produced marked inotropic and chronotropic effects with significant increases in heart rate, cardiac output, arterial blood pressure, and left and right ventricular stroke work. The arterial blood pressure and the left ventricular stroke work increased significantly more with dopamine than with prenalterol, however. The systemic vascular resistance decreased significantly with prenalterol, whereas it was unchanged with dopamine. The effects of prenalterol could be traced after 90 min, whereas the effects of dopamine vanished within 15 min.     

How are haemodynamic and metabolic responses to haemorrhage influenced by segmental thoracic and thoracolumbar epidural analgesia? An experimental study in dogs

To determine the effects of the spread of sympathetic blockade administered prior to haemorrhage on haemodynamic and metabolic responses 10 haemorrhage, we compared these responses among dogs treated by segmental thoracic epidural analgesia, thoracolumbar epidural analgesia and general anaesthesia. Group 1 of six dogs received 0.2% halothane plus epidural analgesia ranging from C₄ to T₅, group 2 of seven 0.2% halothane plus epidural analgesia ranging from C₅ to L₇, and group 3 of eight 0.9% (1 MAC) halothane anaesthesia. A volume of 35 ml · kg^-1 was bled over 30 min. The haemodynamic, metabolic and catecholamine variables were measured repeatedly at 30-min intervals for 2.5 h. The mean arterial pressure decreased significantly in all groups immediately after haemorrhage. It recovered to 80–90 mmHg at 2–2.5 h in groups 1 and 3 but remained at 20–30 mmHg in group 2. The cardiac output decreased significantly in all groups. The systemic vascular resistance increased significantly in group 1 but decreased significantly in group 2. In group 3 it decreased significantly but soon recovered. Arterial pH and base excess decreased significantly in all groups immediately after haemorrhage. After that, base excess recovered slowly in groups 1 and 3 but decreased further in group 2. The plasma epinephrine concentration increased immediately after haemorrhage and then decreased slowly in groups 1 and 3. In group 2 it remained unchanged at the lower level. The decreases in mean arterial pressure, systemic vascular resistance and base excess were significantly larger in group 2 than in groups 1 and 3. These results demonstrate that the haemodynamic and metabolic changes after haemorrhage are milder under segmental thoracic epidural analgesia or 1 MAC halothane anaesthesia than under thoracolumbar epidural analgesia. Widespread epidural analgesia would weaken haemodynamic and metabolic compensatory responses to haemorrhage.     

Hemodynamic response to pumpless extracorporeal membrane oxygenation

Respiratory support by means of arteriovenous extracorporeal membrane oxygenation driven by systemic arterial pressure, in contrast to pump-driven venoarterial extracorporeal membrane oxygenation, is attractive because of its simplicity and lack of trauma to formed blood elements. Although arteriovenous extracorporeal membrane oxygenation has been shown to improve arterial blood gases, useful levels of arteriovenous extracorporeal membrane oxygenation shunt flow may exert detrimental effects on systemic and pulmonary hemodynamics. Therefore the hemodynamic consequences of arteriovenous extracorporeal membrane oxygenation were studied in 11 dogs that were anesthetized, heparinized, and their lungs mechanically ventilated (FIO2 = 0.21) before and after induction of oleic acid pulmonary edema. The data indicate that arteriovenous extracorporeal membrane oxygenation shunt flows adequate to improve arterial blood gases resulted in significant changes in peripheral vascular resistance (-46%; p less than 0.05), systemic arterial blood pressure (-20%; p less than 0.05), and cardiac output (+110%; p less than 0.05). Dopamine infusion (5 micrograms/kg/min) proved to be more effective than volume expansion (15 ml/kg) in maintaining cardiac output, arterial blood pressure, and arterial blood gases. We conclude that pumpless arteriovenous extracorporeal membrane oxygenation, at flow rates adequate for respiratory support, can adversely alter systemic hemodynamics. However, these effects can be beneficially modulated by a moderate dose of inotropic medication.     

Maternal cardiac output response to colloid preload and vasopressor therapy during spinal anaesthesia for caesarean section in patients with severe pre‐eclampsia: a randomised,controlled trial

We examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre‐eclampsia. Twenty patients with pre‐delivery spinal hypotension were randomly allocated to receive an initial dose of either 50 μg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300‐ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min^?1.m^?2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min^?1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049). Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min^?1.m^?2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 [50–150] μg phenylephrine or 15 [7.5–37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at ?12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at ?9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. ?1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesia‐induced haemodynamic changes in severe pre‐eclampsia, if left ventricular systolic function is preserved.     

The effect of a pre-operative infusion of Ringer's solution on splanchnic perfusion in patients undergoing coronary artery bypass grafting

Surgical patients develop a fluid deficit during pre-operative starvation. This study examines the effects of pre-operative fluid administration on haemodynamic variables, oxygenation and splanchnic perfusion in patients undergoing elective coronary artery bypass grafting. Forty-eight patients were randomised to receive either a pre-operative crystalloid infusion (crystalloid group, n = 24) or no infusion (control group, n = 24). Patients in the crystalloid group received a continuous infusion of Ringer's solution at 1.5 ml.kg(-1).h(-1) from 22:00 h until induction of anaesthesia the next morning. Immediately before induction of anaesthesia, all patients were given a colloid infusion to increase pulmonary capillary wedge pressure and central venous pressure to similar levels in both groups. Haemodynamic and oxygenation parameters were measured using invasive cardiovascular monitoring, and splanchnic perfusion was assessed by indocyanine green clearance. Patients in the crystalloid group received a mean (SD) of 1008 (140) ml of Ringer's solution overnight. Patients in the crystalloid group had a higher splanchnic blood flow than the control group before induction of anaesthesia [mean (SD) = 1782 (573) ml.min(-1) vs. 1391 (333) ml.min(-1), p < 0.05]. There were no significant differences in systemic haemodynamic data and global oxygenation parameters between the two groups. Pre-operative infusion of crystalloid appears to result in an improvement in pre-operative splanchnic perfusion.     

Effects of Thoracic Epidural Block and the Beta-1 -Adrenoreceptor Agonist Prenalterol on the Cardiovascular Response to Infrarenal Aortic Cross-Clamping in Man

Sixteen patients scheduled for abdominal aortic resection and grafting were randomly assigned to two groups to study the cardiovascular effects of infrarenal aortic cross-clamping. The patients in the first group had received a thoracic epidural block followed by intravenous administration of the selective beta-1-adrenoreceptor agonist prenalterol prior to induction of general anaesthesia. The patients in the second group served as controls and received no specific treatment prior to general anaesthesia. In both groups, aortic cross-clamping was followed by an equal rise in pulmonary artery diastolic pressure and mean systemic arterial pressure. There was a significant difference in systemic vascular resistance, as the control group had a 46% increase 30 s after cross-clamping, while the pretreated patients had only a 7% increase at the same time. Moreover, the patients given the thoracic epidural block followed by prenalterol increased their stroke volume and cardiac indices, as compared to the patients in the control group who showed a significant decrease in these parameters. Possible mechanisms for the mode of action of the combined thoracic epidural block and beta-1-adrenoreceptor agonist pretreatment are discussed.     

Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy

Background : Increased sympathetic activity perioperatively and associated cardiovascular effects play a central role in cardiovascular complications. High thoracic epidural blockade attenuates the sympathetic response, but even with complete pain relief, haemodynamic and endocrine responses are still present. Beta–adrenoceptor blockade is effective in situations with increased sympathetic activity. This study was designed to evaluate the perioperative haemodynamic effect of preoperative βblockade and its influence on the haemodynamic aspects of the surgical stress response.
Methods : Thirty–six otherwise healthy patients undergoing elective thoracotomy for lung resection were randomised doubleblinded to receive either 100 mg metoprolol or placebo preoperatively. Anaesthesia was combined high thoracic epidural block and general anaesthesia. The epidural analgesia was continued during recovery. Patients were monitored with ECG, pulse oximetry, invasive haemodynamic monitoring, arterial blood gases and electrolytes.
Results : After induction of anaesthesia the mean arterial pressure (MAP) decreased in both groups, and decreased further in the placebo group after initiation of the epidural block. The heart rate (HR) was slightly less throughout the observation period after metoprolol. Peroperatively, the only difference in measured haemodynamics was a marginally higher MAP after metoprolol. Postoperative cardiac index (CI) was lower with a lower variability and cardiac filling pressures were slightly higher in the metoprolol group. The oxygen consumption index was higher after placebo throughout the observation period, with no difference in the oxygen delivery.
Conclusion. We found that preoperative β–blockade during combined general anaesthesia and high thoracic epidural blockade stabilised perioperative HR and CI and decreased total oxygen consumption.     

Cardiovascular effects of midazolam and thiopentone for induction of anaesthesia in Ill surgical patients

The cardiovascular effects of midazolam (0.15 mg kg-) and thiopentone (3.0 mg kg₁) were compared during induction of anaesthesia in 20 American Society of Anesthesiologists class HI patients. In patients given thiopentone (N = 11), cardiac output, mean arterial pressure, heart rate, and systemic vascular resistance all decreased significantly over the course of the study period; mean right atrial pressure rose slightly, and stroke volume remained the same. Patients receiving midazolam (N = 9) experienced similar haemodynamic changes which were significant relative to baseline only for the fall in mean arterial pressure and the rise in mean right atrial pressure at ten minutes. There were no significant differences between the two groups. Midazolam thus appears to be at least as acceptable an induction agent as thiopentone in ill patients, from a haemoaynamic point of view.     

Haemodynamic Effects of Midazolam in the Anaesthetized Patient with Coronary Artery Disease

The haemodynamic effects of midazolam 0.25 mg/kg administered intravenously were studied in eight anaesthetized patients suffering from coronary artery disease. Heart rate, systemic and pulmonary pressures, right atrial pressure, capillary pressure and cardiac output were measured 2, 5, 8 and 12 min after injection of midazolam and were compared with reference values collected before the commencement of the haemodynamic test. The cardiovascular condition of all the patients followed the same course after the injection of midazolam. The greatest variations were seen at the twelfth minute, with the exception of capillary pressure where the largest decrease was noted at the eighth minute. These variations, expressed as a percentage of the initial values, were: mean arterial pressure -17% (P less than 0.01); capillary pressure -23.5% (eight minute, P less than 0.01); heart rate - 9% (P less than 0.01); cardiac index -9% (P less than 0.01); systemic vascular resistance -12% (eighth minute, P less than 0.01). The stroke volume was well maintained (+0.1% NS). These haemodynamic variations were accompanied by a favourable evolution of the endocardial viability ratio (EVR), +12% (P less than 0.01). The slight tachycardia occasionally seen on induction of anaesthesia with midazolam was not seen in this group of patients. We conclude that these haemodynamic variations leading to an increase in EVR support the use of midazolam as a supplement to fentanyl anaesthesia for patients with coronary artery disease.     

Midazolam as Adjunct to High-Dose Fentanyl Anaesthesia for Coronary Artery Bypass Grafting Operation

The usefulness of midazolam as an adjunct during high-dose fentanyl anaesthesia was studied by following the changes in the haemodynamics and total body oxygenation after an intravenous injection of 0.075 mg/kg and 0.15 mg/kg of midazolam during the induction of fentanyl (75 micrograms/kg)-oxygen anaesthesia for a coronary artery bypass operation. These responses were then compared to the changes seen in patients receiving the same fentanyl anaesthesia without the midazolam. A rapid decline after the midazolam injection was seen in the mean systemic arterial pressure (24-32%--the lowest individual value was 45 mmHg (6.0 kPa)) and in the systolic and diastolic pulmonary arterial pressures (29-33% and 30-31%) in 1-3 min. As measured 10 min after the midazolam injection, a decrease from the baseline was seen in the stroke index (25-30%), in the left ventricular stroke work index (46-42%) and in the right ventricular stroke work index (48-61%). These haemodynamic variables remained on a lower level throughout the study period (40 min) in the midazolam patients as compared to the controls. The tissue oxygenation seemed to be sufficient in all groups during the study period. An intravenous injection of a relatively low dose of midazolam during the induction of high-dose fentanyl anaesthesia seems to be followed by rapidly increased venous pooling and a moderately to severely decreased systemic arterial pressure. Based on the results of this study, midazolam cannot be recommended as an adjunct during high-dose fentanyl anaesthesia.     

Trendelenburg positioning does not prevent a decrease in cardiac output after induction of anaesthesia with propofol in children

BACKGROUND AND OBJECTIVE: Induction of anaesthesia may cause decreased cardiac output and blood pressure. Head-down tilt is often the first clinical step to treat hypotension. The objective of this randomized single centre study was to determine, with the use of impedance cardiography (ICG), whether Trendelenburg positioning modifies the haemodynamic response to propofol/fentanyl induction of anaesthesia in ASA I children. METHODS: Thirty ASA I children aged between 7 and 16 years scheduled for elective minor orthopaedic surgery were included. After intravenous induction with propofol and fentanyl in the head-down group (HDG, n = 15), 5 min of 20 degrees head-down tilt was applied. In the supine group (SG, n = 15), no change in the supine position was made. Heart rate (HR), mean arterial blood pressure (MABP), end-tidal carbon dioxide (ETCO(2)), stroke volume index (SVI), cardiac index (CI), systemic vascular resistance index (SVRI) and Heather index (HI) were recorded before (B), at 3 (A(3)), 5 (A(5)) and 8 (A(8)) minutes after induction in each group. RESULTS: After induction, a significant decrease in CI, MABP, HR and HI was recorded in both groups. In the study group, significantly lower values of HR (66 vs. 78 beat/min) and higher values of SVI (42.9 vs. 40.6 ml/min/m(2)) were measured at A(3) compared with the control group. After induction, no difference in CI and SVRI was found between the two groups. CONCLUSION: The present study shows that cardiac performance is not improved by Trendelenburg positioning after propofol/fentanyl induction of anaesthesia in children.     

Haemodynamic effects of intravenous bupivacaine during high thoracic epidural anaesthesia

Administration of small doses of bupivacaine epidurally at the upper thoracic level will partially block the cardiac sympathetic nerves but not the sympathetic outflow via the adrenals. Local anaesthetics have direct systemic effects on the myocardium and the systemic circulation. The present study aimed to examine the effect of high thoracic epidural anaesthesia (TEA) in elderly patients, and to examine the effect of raising plasma bupivacaine concentrations in these patients, who had earlier had the sympathetic innervation of the heart blocked by thoracic epidural anaesthesia. Fifteen elderly patients scheduled for thoracotomy took part in the study. All received high thoracic epidural anaesthesia including the upper five thoracic dermatomes. When epidural block was established, ten patients received bupivacaine 3 mg/min intravenously for 20 min, while five patients received a corresponding volume of normal saline solution. After TEA was established, heart rate, mean arterial blood pressure and cardiac output decreased. When bupivacaine was given to these patients intravenously during the block, mean arterial blood pressure increased, while cardiac output decreased still more. The mechanisms behind these effects seem to be a direct constriction of the systemic blood vessels and a depressive effect on the myocardium, which was blocked from the influence of the cardiac sympathetic nerves by the high thoracic epidural block.     

Anaesthesia for a non cardiac surgery in a patient with an Eisenmenger syndrome. Interest of a non invasive haemodynamic monitoring

Patients with an Eisenmenger syndrome have an instuble hemodynamic status. During a general anaesthesia, the intracardiac shunt has to maintain the correct orientation and volume, adapted to each patient, in such a condition, to avoid the risk of hypoxemia and cardiac failure. The haemodynamic monitoring with a Swan Ganz catheter could be useful. But it is necessary to evaluate the advantage and the risks when the technique is used in these pathological circumstances. Moreover, when the cardiac output is measured with the thermodilution technique, the right-left intra cardiac shunt volume, is not taking into account. The continuous haemodynamic monitoring, with a simplified transoesophageal echo-Doppler system, as it was done in this case, allows appreciate the real quantitative variations of the shunt. In this way the more adequate calculation of some others haemodynamic parameters, over all the total systemic vascular resistances, allows a more precise therapeutic approach.