Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 343 records · Page 19Linked to original sources

PubMed1991

[Pharmacokinetics and pharmacodynamics of local anesthetics].

In clinical practice the efficacy of local anaesthesia is judged by the time of onset, duration and the quality of sensory and motor blockade. Apart from the physicochemical properties of local anaesthetics, a sufficient blockade depends on the volume and the concentration which are applied. Generally increasing the dose leads to a better quality of blockade as well as a higher risk of toxicity. This dilemma is evident in procedures, where, due to continuous or repetitive application within one day, the applied total dosage exceeds the recommended maximum limit. The values regarding maximum doses published in the German Pharmacopeia ("Rote Liste") can be defined as being more or less the product of the volume of distribution and the toxic concentration in the plasma. According to that formula the maintainance doses for continuous techniques in regional anaesthesia are derived from the product of the elimination half-life and the toxic plasma concentration. The values for toxic plasma concentrations are difficult to define since only the free protein-unbound fraction of a local anaesthetic is responsible for undesired side-effects. This fraction can be influenced by acidosis, body temperature and shortage of specific binding protein. Some well documented case reports show that another major cause of acute toxicity is nearly always due to inadvertent intravascular injections. This event can occur nearly unnoticed and leads to life-threatening complications even with lower doses than the recommended maximum doses. Only the application of high concentrations into well vascularised regions is followed by a similarly quick development of high plasma levels. Typical kinetics of local anaesthetics are presented for various methods of regional anaesthesia informing the anaesthetist on corresponding plasma concentrations if the recommended maximum doses are exceeded and thus he gets useful information for his daily work.

Anesthesia, Conduction↗

PubMed1991

[Absorption of adrenaline after local administration to the eye].

Twenty patients undergoing surgery for correction of strabismus under general anesthesia were randomly selected to receive conjunctival application of 100 microliters (20 micrograms) adrenaline in both eyes or in neither (controls). A further 20 patients undergoing cataract surgery with local anesthesia were randomly selected to receive 1 ml adrenaline 1:10 000 (100 micrograms) or 1 ml balanced salt solution (controls) in the anterior chamber. Adrenaline in plasma was measured in six time points within 15 min (correction of strabismus) or at seven within 30 min (cataract surgery). Plasma levels of adrenaline, mean arterial pressure, and heart rate were comparable in treatment groups and controls. No severe arrhythmias were observed. Neither conjunctival application of 20 micrograms adrenaline or instillation of 100 micrograms adrenaline into the anterior chamber increases adrenaline levels in plasma, and there is no reason to suspect cardiovascular interactions.

Adolescent↗

PubMed1991

[Hemodynamic effects of enoximone--comparative studies of heart surgery patients].

Treatment of depressed myocardial pump function during cardiac surgery is usually based on catecholamines. Development of selective phosphodiesterase (PDE)-III-inhibitors such as enoximone seems to be an interesting aspect in treating myocardial dysfunction in this situation. In patients undergoing aorto-coronary bypass grafting, who where unable to be weaned from cardiopulmonary bypass (CPB) without pharmacologic support, i.v. injection of enoximone (0.5 mg/kg) resulted in significant better hemodynamics than after infusion of dobutamine in comparable patients. The mechanisms for improvement in ventricular function induced by enoximone appear to be enhanced contractility, owing to its positive inotropic effects, and a decrease in ventricular outflow resistance, resulting from peripheral vasodilation. The positive hemodynamic effects in patients additionally treated with catecholamines (epinephrine) may be of particular interest in patients with beta-receptor down-regulation phenomenon.

Blood Pressure↗

PubMed1991

[Bronchial rupture. Diagnosis and therapy of a rare complication of the use of double-lumen tubes].

For anesthesia during thoracic surgery, it is common to use a double-lumen endotracheal tube for one-lung ventilation. Double-lumen tubes protect the bronchial system of the healthy lung from being occluded by blood or pus coming from the operated lung. Therefore, in cases of lung abscess, bronchial hemorrhage, lung cyst, or localized lung infection the use of a double-lumen tube is advisable. Facilitating operation and reduced operating time are further advantages of intubation with a double-lumen tube for independent ventilation of both lungs. Due to the rigidity of these tubes, however, there are disadvantages such as injuries to the trachea and bronchial system. We report a case of rupture of the left main bronchus after insertion of a Carlens tube. The intraoperative symptoms of airway leakage are demonstrated, the process of locating and repairing the injury is described. In our case the postoperative course was not complicated; the patient left the hospital 10 days after operation. Causes of bronchial rupture, its therapy, and prophylactic measures are also discussed.

Bronchi↗

PubMed1991

[Ultrafiltration as a fast and simple method for determination of free and protein bound prilocaine concentration. Clinical study following high-dose plexus anesthesia].

Ultrafiltration as a Fast and Simple Method to Separate Free and Protein Bound Concentrations of Local Anesthetics/Pharmacokinetic studies following high-dose anesthesia of the axillary plexus. As many other drugs amide-type local anesthetics are protein bound in plasma. The extent of binding varies between local anesthetics. The free, non protein-bound fraction of these drugs is mainly responsible for cardiovascular and central-nervous side effects. If high doses are necessary for regional anesthetic procedures it seems reasonable to determine the pharmacological active, non protein-bound fraction in addition to the total concentration of the local anesthetic drug. Analyses of protein binding was performed using an ultrafiltration method which is discussed in this paper. Total (HPLC) and unbound plasma levels (combination of ultrafiltration and HPLC) of the local anesthetic drug in central venous blood were studied in 20 healthy orthopedic patients, undergoing plastic surgery of the upper limb (elbow, forearm, hand), over a time period of 90 min, when performing axillary plexus block with 30 ml prilocaine (CAS 721-50-6) 2% (= 600 mg). Separation of the local anesthetic fractions was achieved using the ultrafiltration system MPS-1, equipped with a YMT-membrane. These membranes have a narrow pore size retaining molecules larger than 30000 Dalton. Ultrafiltration was accomplished by subjecting 1.2 ml of plasma to centrifugation at 2000 x g for 60 min at 30 degrees C using a clinical centrifuge equipped with a 35 degree angle head rotor. The plasma samples were adjusted to physiological pH (7.40) with a sodium-potassium-phosphate buffer. The tightness of the used membrane was controlled by a micromethod for protein estimation (sensitivity 10 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗

PubMed1991

[Is the plasma protein binding of lidocaine modified by the simultaneous administration of midazolam?].

Perioperative antiarrhythmic therapy with lidocaine (bolus dosage 100 mg followed by infusion of 200 mg/h) was performed in 24 patients; 12 of them simultaneously received an intravenous injection of 10 mg midazolam with the bolus of lidocaine (group I: with midazolam; group II: without midazolam). Central venous blood samples were collected over a period of 1 h (1, 3, 5, 10, 20, 30, and 60 min after the bolus) to evaluate unbound and total (protein-bound + unbound) plasma concentrations of lidocaine, thus calculating plasma protein binding. One minute after intravenous administration of lidocaine peak plasma concentrations occurred: in group I 5.38 +/- 1.99 micrograms/ml (mean +/- SD), in group II 5.25 +/- 1.90. Up to 60 min there was only a gradual decrease in plasma concentrations in both groups. There was no significant difference between the two groups (group I: mean free concentration 0.67-0.80 micrograms/ml; mean total concentration 4.84-5.38 micrograms/ml; mean plasma protein binding 83%-86%; group II: 0.69-0.89 micrograms/ml; 4.62-5.25 micrograms/ml; 82%-85%). We draw the conclusion that midazolam administration is safe in patients undergoing antiarrhythmic therapy or regional anesthesia with lidocaine.

Adult↗

PubMed1991

[The stress reaction in the recovery phase from halothane and isoflurane anesthesia].

This study was undertaken to investigate the influences of halothane and isoflurane as well as different extubation techniques on the endocrine stress response during recovery from general anesthesia. Forty patients scheduled for herniorrhaphy and cholecystectomy were randomly allocated to 4 groups: 20 received halothane and 20 received isoflurane anesthesia. Within the halothane and isoflurane groups, 10 patients each were extubated during anesthesia (1/2 MAC) and a further 10 had awake extubation. Premedication, induction of anesthesia, and intraoperative anesthetic management were standardized in all groups. Plasma levels of endocrine stress parameters as well as mean arterial pressure (MAP), heart rate (HR), and arterial oxygen saturation (SaO2) were measured at nine time points up to 60 min after extubation. Biometric data and duration of operation and anesthesia were comparable in all groups. In the recovery period, epinephrine levels were higher in the isoflurane groups than in the halothane groups (P = 0.02). With respect to time course, earlier and more marked increases of epinephrine, norepinephrine, and antidiuretic hormone (ADH) levels were observed in the isoflurane groups compared to the halothane groups (P less than 0.01), representing the more rapid elimination of isoflurane. The sympathoadrenergic stress response was more pronounced in patients with extubation during anesthesia than in those with awake extubation: epinephrine levels were slightly higher and group levels of norepinephrine were significantly increased (P = 0.02). No influence of the extubation techniques was observed on ADH, ACTH, and cortisol levels or on MAP, HR, or SaO2. In summary, extubation during anesthesia did not reduce the endocrine stress response. It is concluded that awake extubation should be preferred unless the operation or the patient's condition requires extubation during anesthesia.

Adult↗

PubMed1991

[Pharmacokinetic studies of blood protein binding of bupivacaine following acute preoperative hemodilution].

This randomized study was designed to determine the effects of isovolemic hemodilution and lumbar epidural anesthesia on plasma concentrations of bupivacaine in patients scheduled for endoprosthetic hip surgery. PATIENTS, MATERIALS AND METHODS. The patients were randomly assigned to two groups. In a hemodilution group (n = 15), which included patients undergoing lumbar epidural anesthesia following isovolemic hemodilution (15 ml/kg body weight), withdrawn blood was substituted by colloidal solution (hydroxyethyl starch solution 6%, 450/0.7; ratio of replacement 1:1). Controls were 15 patients who were not subjected to isovolemic hemodilution; epidural anesthesia only was performed. Both groups had identical fluid pretreatment (1000 ml Ringer's solution) before injection of the epidural bupivacaine dose (mean 14 ml, 0.75%); central venous blood samples were drawn at short intervals over 180 min. Both, the total plasma concentrations and the free bupivacaine fractions were determined by HPLC and ultrafiltration. RESULTS. Peak bupivacaine plasma levels (mean 1.30 microgram/ml) were found 10 min after application of the analgesic dose in the control patients. In contrast, in hemodiluted patients mean maximum plasma levels of bupivacaine were measured between the 20th and 30th min, with peak levels of only 0.75 microgram/ml plasma. The unbound bupivacaine levels were not significantly different in both groups over the entire measuring period despite the differing total bupivacaine concentrations. Therefore, protein binding of bupivacaine was about 6% lower in the hemodilution group, especially during the period shortly after injection. DISCUSSION. We conclude that isovolemic hemodilution leads to lower plasma bupivacaine concentrations after epidural anesthesia, probably due to an increased volume of distribution. Protein binding of bupivacaine is reduced by hemodilution; the free, non-protein-bound concentrations of local anesthetic were not associated with any systemic side effects in this study.

Aged↗

PubMed1991

[The use of ketamine and midazolam for analgesia and sedation in ventilated patients subject to obligatory treatment with catecholamines].

This study was undertaken to compare two regimens for analgesic sedation in intensive care patients with exogenous catecholamine therapy, giving special regard to catecholamine demand and hemodynamic parameters. A total of 20 ventilated patients in a surgical intensive care unit were investigated in a prospectively randomized design. Exogenous catecholamine therapy with epinephrine and/or norepinephrine was started at systolic pressure (SAP) less than 85 mmHg or mean arterial pressure (MAP) less than 65 mmHg to maintain cardiovascular function. For analgesic sedation, patients received bolus injections of about 0.2 mg/h fentanyl and 2.5 mg/h midazolam (fentanyl group, n = 10) or an infusion of about 50 mg/h ketamine and 2.5 mg/h midazolam by syringe pump (ketamine group, n = 10). Before the investigation, all patients received fentanyl and midazolam. The study period was 48 h. During the course of the study, mean catecholamine dosage increased significantly in the fentanyl group from 12.1 to 16.3 micrograms/min (+33%, P = 0.003). In the ketamine group, mean catecholamine dosage decreased from 43.9 to 38 micrograms/min (-13%, P = 0.19). No significant differences in group levels or time course were observed with regard to MAP, heart rate, cardiac index, pulmonary capillary wedge pressure, and shunt volume. Levels of pulmonary artery pressure (PAP) were comparable in both groups (ketamine group 29 mmHg, fentanyl group 26 mmHg). In time course, PAP increased by about 5 mmHg in the ketamine group but not in the fentanyl group (P = 0.009). The average central venous pressure (CVP) was 12 mmHg in both groups. At the end of the investigation, CVP decreased in the fentanyl group and increased in the ketamine group (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

The new phosphodiesterase inhibitor enoximone in patients following cardiac surgery--pharmacokinetics and influence on parameters of coagulation.

Enoximone is a selective inhibitor of the phosphodiesterase-III enzyme (PDE-III) and possesses positive inotropic and vasodilatory properties. The PDE-inhibitor amrinone has been associated with adverse effects on coagulation by decreasing platelets. To investigate the influence of enoximone on hemostasis, 18 patients undergoing elective aorto-coronary bypass grafting and receiving enoximone were compared to a control group (n = 18). In addition, the plasma levels of enoximone and its major metabolite (enoximone-sulfoxide) were studied following a single injection (0.5 mg/kg) and during a continuous infusion (5 and 10 micrograms/kg.min) before, during and after extracorporeal circulation (ECC). No difference between study and control groups was found for the parameters of coagulation during the investigation period; in particular there were no differences in platelet count and platelet function (thrombelastography). Following the single bolus, peak plasma levels decreased during ECC to ineffective levels. Continuous infusion, however, maintained effective plasma levels of enoximone; sulfoxide levels were twice as high as enoximone concentrations up until the end of the investigation period. It is concluded that enoximone can be judged to be safe in respect to its effects on coagulation even following ECC and at relatively high doses. The use of continuous infusion results in plasma levels which remain at an effective concentration through to the time that the patient is transferred to the intensive care unit.

Aged↗

PubMed1990

Comparative effects of enoximone and theophylline on plasma catecholamines and haemodynamics in cardiosurgical patients.

The release of endogenous catecholamines in aorto-coronary bypass graft patients receiving either 0.5 mg/kg enoximone (n = 10), 4.0 mg/kg theophylline (n = 10) or saline solution (control, n = 10) has been studied, as well as certain haemodynamic parameters. Adrenaline (A) and noradrenaline (NA) concentrations were not significantly changed by the administration of enoximone. Theophylline caused a small increase in NA (+40% in the 1st min) and a marked increase in A (approximately +7000% in the 1st min), which still remained elevated at the end of the investigation period (+220% in the 30th min). The major haemodynamic effects of enoximone were a significant increase in cardiac index (CI; +35%) and a decrease in pulmonary capillary wedge pressure (PCWP; -27%), pulmonary artery pressure (PAP; -21%), RVEDV and RVESV, while the heart rate (HR) remained almost unchanged. The dominant haemodynamic effects of theophylline were an increase in HR (+26%; arrhythmia in 3 patients), PAP (+22%), and RVEDV (+19%), while RVESV (+26%), MAP (-16%), CI (-14%), and RVEF (-15%) fell significantly. It is concluded that the haemodynamic actions of enoximone are not mediated by catecholamine release, whereas the adverse cardiovascular effects of theophylline might partly be explained by the significant increase in plasma adrenaline.

Cardiac Catheterization↗

PubMed1990

RETRACTED: Acute preoperative plasmapheresis and established blood conservation techniques.

Plasmapheresis performed weeks before an operation producing autologous plasma has proved to be of benefit in elective operations. First experiences in acute plasmapheresis, which is performed immediately before the operation, have been reported recently. When acute plasmapheresis is used in cardiac operations, however, it must be viewed in connection with other techniques for reducing blood consumption such as the Cell Saver (CS) and ultrafiltration devices. In 60 patients undergoing elective aortocoronary bypass grafting, acute plasmapheresis was performed, producing either platelet-poor plasma or platelet-rich plasma, in combination with either the Cell Saver or hemofiltration. Fluid balance during cardiopulmonary bypass was significantly lower in the hemofiltration patients. Postoperatively, none of these patients received donor blood, whereas 4 patients of the Cell-Saver groups needed packed red blood cells. AT-III, fibrinogen, the number of platelets, albumin, total protein, and colloid osmotic pressure were less compromised when hemofiltration was used in combination with acute plasmapheresis in contrast to combination with the Cell-Saver technique. Plasma hemoglobin was without differences during the investigation period, and polymorphonuclear elastase was less increased when platelet-rich plasma was produced preoperatively. On the first postoperative day, most of the differences between the groups had already disappeared. We conclude that when acute plasmapheresis is used in cardiac operations, discarding of plasma by the Cell Saver should be avoided and ultrafiltration devices should replace centrifugation techniques for blood conservation.

Blood Coagulation Factors↗

PubMed1990

Enoximone treatment of impaired myocardial function during cardiac surgery: combined effects with epinephrine.

Enoximone belongs to a new class of noncatecholamine-positive inotropes, which selectively inhibit phosphodiesterase type III and increase cyclic AMP (cAMP). This study was performed in 30 coronary artery surgery patients with impaired myocardial function (ejection fraction [EF] less than 50%). The study's two purposes were to investigate the hemodynamic effects of enoximone, 0.5 mg/kg, administered following induction of anesthesia (phase I), and to assess whether enoximone can potentiate the actions of sympathomimetic agents during weaning from cardiopulmonary bypass (CPB) (phase II). Starting with already reduced hemodynamics, induction of anesthesia led to a further deterioration of blood pressure and cardiac output (CO). Administration of enoximone produced a significant increase in cardiac index (CI) (+47%), whereas pulmonary capillary wedge pressure (PCWP) (-37%), pulmonary artery pressure (PAP) (-17%), and systemic vascular resistance (SVR) (-17%) were significantly reduced. Heart rate (HR) was not increased, and no dysrhythmias occurred during the investigation. The hemodynamic effects were maintained for 30 minutes until the start of the operation. In phase II, where weaning from CPB was not possible without pharmacological support, either enoximone (0.5 mg/kg) + epinephrine (0.1 micrograms/kg/min) or only epinephrine (same dosage) was randomly selected. Weaning was successful in both groups, but the combined therapy produced a larger increase in cl and a more pronounced decrease of the elevated filling pressure (PCWP). PAP was not changed in the combined therapy group, but increased in the patients receiving epinephrine alone. It is concluded that enoximone has beneficial hemodynamic effects in the perioperative period, and that potentiation of the effects of epinephrine in severe heart failure may be one of the drug's most useful features.

Aged↗

PubMed1990

Acute plasmapheresis during cardiac surgery: volume replacement by crystalloids versus colloids.

Acute plasmapheresis (APP) is an additional tool for blood conservation during cardiac surgery. In a randomized study of 60 aortocoronary bypass patients undergoing APP, the influence of replacement of the withdrawn autologous plasma (10 mL/kg) by either colloids (low molecular weight hydroxyethyl starch solution [6% HES 200/0.5]) or crystalloids (Ringer's solution) was investigated. APP was performed by means of a centrifugation technique producing platelet-poor plasma. During and after cardiopulmonary bypass (CPB), either a cell saver (CS) or a hemofiltration (HF) device was also used for blood concentration. Almost three times as much crystalloid as HES solution was necessary for replacement of autologous plasma. Fluid balance during CPB was significantly more positive in the crystalloid patients, particularly when a CS was used. Blood loss was highest in the crystalloid patients in whom a CS was used in addition to APP, and these were the only patients who needed packed red cells. The platelet count, AT-III and fibrinogen plasma concentrations, colloid osmotic pressure, albumin, and total protein were significantly less compromised in the patients with colloid volume replacement. These parameters were closest to control values in patients receiving colloid replacement and HF. It is concluded that colloid is preferred for replacement of autologous plasma withdrawn by APP, and HF is superior to the CS when the combined technique for blood conservation is used.

Coronary Artery Bypass↗

PubMed1990

Lung management during cardiopulmonary bypass: influence on extravascular lung water.

Progressive respiratory insufficiency secondary to cardiopulmonary bypass (CPB) is still a hazard after cardiac surgery. Pathophysiologically, impaired capillary endothelial integrity seems to be the fundamental lesion, followed by increased interstitial fluid accumulation. The reasons for this pulmonary damage are controversial; however, management of the nonperfused lungs during CPB has been widely neglected and may be partly responsible. In this study, 90 patients undergoing coronary artery bypass grafting were randomly divided into six groups (15 patients each) with different management of the lungs during CPB: group 1, lungs collapsed (0/0); group 2, static inflation with +5 cm H2O and F1O2 1.0 (+5/1.0); group 3, static inflation with +5 cm H2O and F1O2 0.21 (+5/0.21); group 4, static inflation with +15 cm H2O and F1O2 1.0 (+15/1.0); group 5, static inflation with +15 cm H2O and F1O2 0.21 (+15/0.21); and group 6, controlled mechanical ventilation as before start of CPB (positive end-expiratory pressure [PEEP] +5 cm H2O; F1O2 1.0) (ventilation). In addition to hemodynamic monitoring, extravascular lung water (EVLW) was measured by means of a double-indicator dilution technique with heat and indocyanine green. Measurements were performed after induction of anesthesia, before onset of CPB, and immediately after weaning from bypass, as well as 60 minutes and 5 hours after termination of CPB. Pulmonary gas exchange (PaO2) and intrapulmonary shunting (Qs/Qt) were also measured. Starting from comparable, normal baseline values, EVLW was increased in all groups after weaning from CPB, with the most pronounced increase in group 4 (maximum, +35%) and group 5 (+40%).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

PubMed1990

Transcranial Doppler sonography and somatosensory evoked potential monitoring in carotid surgery.

Ninety-seven patients undergoing 103 carotid operations were studied intraoperatively using somatosensory evoked potentials after median nerve stimulation (SEP) and transcranial Doppler sonography (TCD). SEP were recorded from the scalp (C3'-Fz or C4'-Fz) and from the second cervical vertebra. The amplitude of the primary cortical response (N20P25) was measured peak-to-peak. Central conduction time (CCT) resulted from the difference between the first negative cortical (N20) and cervical (N14) response. TCD was performed using a pulsed 2-MHz-Doppler device to record the mean blood flow velocity of the middle cerebral artery (Vm-MCA) transtemporally. TCD and SEP variables were registered prior to and after carotid clamping, at short intervals during the clamping period, and after declamping. Critical SEP alterations (N20P25 less than 50% and/or CCT greater than 20% compared to the preceding values) were regarded as significant indicators of cerebral ischaemia, and selective intraluminal shunting was generally based on SEP criteria. The incidence of critical SEP changes was compared to Vm-MCA reductions greater than 60% using the Chi2-test. With SEP always recordable, additional TCD monitoring was possible in only 78 patients in our series for technical or anatomical reasons. Vm-MCA reductions greater than 60% were associated with critical SEP alterations in six cases. In five patients, Vm-MCA was reduced greater than 60% without relevant SEP changes, whereas one patient with critical SEP findings had only a minor Vm-MCA reduction (33%). In the remaining 66 cases, carotid clamping was tolerated without critical SEP changes associated with Vm-MCA reductions not exceeding 60%.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗

PubMed1990

Effects of nitrous oxide on endocrine stress response and haemodynamic parameters during coronary artery surgery.

To compare simultaneously the influence of nitrous oxide on haemodynamic parameters and on surgical stress response, 20 patients scheduled for coronary artery bypass graft were investigated during standardized modified neurolept anaesthesia. Before onset of cardiopulmonary bypass, one group received nitrous oxide and oxygen (2:1), whereas in the other group air with oxygen (F10(2) 0.33) was used. Increases in adrenaline, noradrenaline, ADH, and cortisol were slightly less and mean arterial pressure and cardiac output reached markedly lower levels in the nitrous oxide group. When nitrous oxide is not acceptable for a cardiac surgery patient during modified neurolept anaesthesia due to haemodynamic side effects enhancing intravenous application of anaesthetics to compensate the analgetic properties of the substance should be considered.

Adrenocorticotropic Hormone↗

PubMed1990

Haemodynamic effects of the phosphodiesterase inhibitor enoximone in comparison with dobutamine in esmolol-treated cardiac surgery patients.

In a randomized study, the haemodynamic effects of the new phosphodiesterase-III-inhibitor, enoximone, were compared with dobutamine in acutely beta-adrenoceptor blocked patients. Twenty patients scheduled for aorto-coronary bypass grafting suffering from tachycardia (heart rate (HR) greater than 100 beat min-1) were treated by infusion of esmolol, an ultra-short acting, selective beta 1-blocker. Twenty minutes after the start of esmolol, either enoximone 0.5 mg kg-1 as a bolus (n = 10) or dobutamine 5 micrograms kg-1 min-1 was administered. Haemodynamic effects were monitored for 40 min, including measurement of left ventricular haemodynamics. Esmolol reduced HR (-27%) and dP/dtmax (-38%) significantly in both groups. Cardiac index (CI) was decreased also. Enoximone increased Cl (+35%) and dP/dtmax (+39%) significantly, while no change in dobutamine-treated patients was observed. Systemic vascular resistance increased only in the dobutamine group (+44%).

Adrenergic beta-Antagonists↗