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Biomedical subjects

W Hess

Publications and source records attributed to W Hess.

At least 55 records · Page 3Linked to original sources
PubMed1985

Comparison of phentolamine and urapidil in controlling acute intra-operative hypertension in patients subjected to coronary artery bypass surgery.

Intra-operative hypertensive episodes are a frequent problem in patients undergoing coronary artery bypass grafting. The haemodynamic effects of the alpha-adrenergic blocking drugs phentolamine and urapidil, two alpha-adrenergic blocking drugs with a different alpha-receptor subtype specificity, when used to control intra-operative hypertension were evaluated. Ten patients received phentolamine (about 25 micrograms kg-1 min-1) and ten patients received urapidil (about 100 micrograms kg-1 min-1) to return arterial blood pressure to control levels. Both drugs decreased arterial pressure to baseline values within 2-3 minutes by reducing the elevated systemic vascular resistance. Treatment with phentolamine was accompanied by a marked increase in heart rate with a concomitant increase in cardiac index and the rate-pressure product. Urapidil caused no change in heart rate, but the cardiac index increased. Urapidil lowered the rate-pressure product significantly. Both drugs reduced mean pulmonary artery and pulmonary capillary wedge pressures. The different selectivity of phentolamine and urapidil to alpha 1-and alpha 2-adrenergic receptors induces the diverse haemodynamic effects. We conclude that the use of urapidil is the superior regimen when an alpha-adrenergic blocking agent is favoured as a vasodilator.

Acute Disease↗
PubMed1985

[Dose-dependent effect of amrinone on hemodynamics, myocardial circulation and myocardial energy requirement. An experimental study].

This study was designed to assess the dose-dependent effects of amrinone (1, 2 and 4 mg/kg i.v.) on hemodynamics, myocardial blood flow and myocardial oxygen consumption in anesthetised closed chest dogs (n = 8). Heart rate (HR), cardiac output, mean aortic pressure (MAP), left ventricular end-diastolic pressure (LVEDP), maximum dp/dt (dp/dtmax), myocardial blood flow (MBF) and aorto-coronary sinus oxygen difference (AVDO2 cor) were measured. Cardiac index (CI), stroke volume index (SVI), ejection fraction (EF), total peripheral resistance (TPR), coronary vascular resistance (CVR) and myocardial oxygen consumption (MVO2) were calculated from standard formulas. Amrinone improved myocardial pump function by a direct positive inotropic effect on the myocardium. EF and SVI increased to a maximal degree with 1 mg/kg amrinone (28% resp. 30%). dp/dtmax increased dose dependent (46, 64, 71%). Following a systemic vasodilation due to amrinone, left ventricular filling pressure and TPR decreased significantly. With 1 and 2 mg/kg amrinone MAP remained unchanged. 4 mg/kg produced a distinct fall in MAP accompanied by an increase in HR. The improvement in myocardial contractility did not cause a comparable increase of myocardial oxygen consumption. Due to an unloading of the heart 1 and 2 mg/kg amrinone induced no significant and prolonged augmentation of the myocardial oxygen demand. In the coronary circulation a non energy dependent vasodilation occurred followed by a marked decrease of AVDO2 cor (10, 18, 28%).

Aminopyridines↗
PubMed1984

Nifedipine versus nitroprusside for controlling hypertensive episodes during coronary artery bypass surgery.

Intraoperative hypertensive episodes are a common problem in patients undergoing coronary artery bypass grafting. Twenty patients who developed acute hypertension (mean arterial pressure increase to 110 mmHg) were studied. Ten patients received nifedipine (about 3 micrograms kg-1 min-1) and ten patients nitroprusside (about 0.75 micrograms/kg-1 min-1) to return arterial blood pressure to control levels. All patients were anaesthetized with flunitrazepam, fentanyl, pancuronium and N2O/O2. The study compares the effects of nifedipine and nitroprusside on systemic and pulmonary haemodynamics. Both nifedipine and nitroprusside decreased arterial pressure to baseline values within about 3 min by reducing the elevated systemic vascular resistance. Cardiac filling pressures and pulmonary artery pressure decreased significantly only with nitroprusside. Following nitroprusside cardiac output remained unchanged whereas nifedipine increased cardiac output and stroke volume when blood pressure was lowered by a comparable degree. The data suggest that nifedipine primarily affects resistance vessels in the systemic circulation without significantly changing venous tone as opposed to the effect of nitroprusside. Thus, nifedipine appears to be an appropriate vasodilator for controlling arterial hypertensive episodes in patients with coronary artery disease and normal left ventricular function.

Adult↗
PubMed1984

Combined effects of halothane anesthesia and verapamil on systemic hemodynamics and left ventricular myocardial contractility in patients with ischemic heart disease.

The interaction of halothane anesthesia and intravenous verapamil (0.15 mg/kg over 10 min) was investigated in eight patients scheduled for coronary artery bypass surgery. All patients had a normal left ventricular (LV) function at rest and were on chronic beta-blocker therapy. Halothane produced a marked reduction in mean arterial pressure (MAP), cardiac index, and in LV contractility as documented by a decrease in LV peak positive dP/dt. Verapamil caused an additional depression (16%) of LV peak positive dP/dt accompanied by a small increase (3 mm Hg) in LV end-diastolic pressure. The combined negative inotropic propensities of halothane and verapamil did not produce any overt untoward effects even in the presence of chronic low dose beta-blocker therapy. The predominant hemodynamic effect of verapamil was a systemic vasodilation resulting in a further reduction in MAP (12%) while heart rate remained unaffected. Despite reducing myocardial oxygen demand, caution must be exercised in dose selection in each drug to avoid regional myocardial ischemia due to the combined hypotensive effects of halothane and verapamil.

Adult↗
PubMed1984

[Blood pressure control with an inhalation anesthetic in acute intraoperative hypertension. Hemodynamic profile of halothane, enflurane and isoflurane in coronary surgery patients].

The haemodynamic effects of isoflurane, halothane and enflurane when used to control intraoperative hypertension were evaluated in 30 patients undergoing coronary artery bypass grafting. The patients were anaesthetized with flunitrazepam, fentanyl, pancuronium and N2O-O2. Control measurements were made after skin incision. When mean arterial pressure increased to 110 mmHg due to sternal spread or surgical manipulation of the aorta, halothane, enflurane or isoflurane were administered to return arterial pressure to control levels. Using a non-rebreathing system, inspired halothane concentrations of 1.0-1.5 vol.%, enflurane concentrations of 2.0-2.5 vol.% and isoflurane concentrations of 1.5-2.0 vol.% were necessary. Measurements were repeated during the hypertensive episodes and after treatment with halothane, enflurane or isoflurane while surgical stimulation continued. During the hypertensive episodes marked elevations in systemic vascular resistance were observed, four patients developed ischaemic ST-segment changes. Each of the three inhalational anaesthetics decreased mean arterial pressure to baseline values within 5 to 10 minutes. The fall in blood pressure caused by halothane was mainly due to a reduction in cardiac index, since the elevated systemic vascular resistance almost remained unaffected. Enflurane produced a similar fall in cardiac index, although left ventricular afterload was significantly reduced, suggesting that enflurane caused more impairment of cardiac performance than halothane. In contrast, the administration of isoflurane was associated with an increase of the cardiac index in the presence of marked systemic vasodilation and a slight decrease in left ventricular filling pressure. Halothane, enflurane and isoflurane reduced the rate-pressure product by a comparable degree and, when present, abnormalities in the ST-segments disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1983

[Meckel's diverticulum - results of 155 resections].

A total of 155 cases of Meckel's diverticulum were analyzed: 122 were uncomplicated as opposed to 33 that were complicated. Resection of all uncomplicated diverticula had a course free of difficulty, while there was one death in the cases with complicated diverticula as a result of peritonitis after perforation of the diverticulum. The diagnosis and differentiation of diverticulum from other abdominal clinical pictures, as well as from appendicitis, is usually not possible preoperatively, although differential diagnosis must always be kept in mind. If there are no special contraindications, Meckel's diverticulum is searched for instead and then resected.

Adolescent↗
PubMed1983

The effects of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside on haemodynamics, coronary blood flow and myocardial oxygen consumption - an experimental study.

The influences of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside intravenously on haemodynamics, coronary circulation and myocardial oxygen consumption were investigated in closed chest dogs (n = 8). In an attempt to simulate heart failure the dogs received blood transfusion (15 ml/kg) in the presence of halothane-induced myocardial depression. All three nitrates reduced the loads for the left ventricle. With isosorbide dinitrate and sodium nitroprusside the preload and pulmonary pressure decreased to a greater extent than with glyceryl trinitrate. The haemodynamic results suggest that sodium nitroprusside is the favourable nitrate in left ventricular failure because it produces a balanced reduction in the ratio of pre- and afterload. Four micrograms/kg X min sodium nitroprusside induced marked coronary dilatation; glyceryl trinitrate had only a slight coronary vasodilating effect. With isosorbide dinitrate the myocardial blood flow remained well adapted to oxygen demand, the coronary vascular resistance did not change. Sodium nitroprusside produced a significant change of the transmural myocardial blood distribution-expressed as the epi/endocardial blood flow ratio. The ratio was increased by sodium nitroprusside, much more than by glyceryl trinitrate or isosorbide dinitrate.

Animals↗
PubMed1983

Postoperative malignant hyperthermia and dantrolene therapy.

A case of malignant hyperthermia (MH) in a three-year eight-month-old girl is presented. Definite symptoms of MH developed in the awake patient 30 min after termination of anaesthesia which had lasted five hours. This postoperative MH-episode resolved promptly following intravenous administration of dantrolene (2.5 mg X kg-1 initially, followed by 5 mg X kg-1 over 12 hours). Results of serial serum samples revealed a steady increase in creatine kinase (CK) concentration with the highest value being observed at the second day, despite dantrolene therapy. The unusual occurrence of MH in the postoperative period, when the major effects of anaesthesia were no longer an important consideration, is discussed with regard to the "human stress syndrome." The necessity to give this information to people usually not familiar in diagnosing MH (e.g., medical personnel in surgical wards) is stressed.

Child, Preschool↗
PubMed1983

Cardiovascular interactions of halothane anesthesia and nifedipine in patients subjected to elective coronary artery bypass surgery.

The effects of intravenous (iv) nifedipine (7.5 micrograms/kg over 10 min) on systemic hemodynamics and myocardial contractility were investigated under steady state conditions of halothane anesthesia (0.5 MAC) in 8 patients scheduled for elective coronary artery bypass surgery. All patients received long-term medication in the form of beta adrenergic receptor blockers and had a normal global left ventricular function at rest. Halothane produced a marked reduction in left ventricular contractility as documented by a considerable fall in LV max dP/dt. Nifedipine caused a small additional depression of LV max dP/dt without affecting LVEDP significantly. The slight myocardial depressant effect of nifedipine was counterbalanced by a concomitant reduction in left ventricular afterload due to a decrease in the systemic vascular resistance resulting in unchanged or even improved cardiac output. The results indicate that iv nifedipine in the doses used here is safe for patients with ischemic heart disease, even in the presence of already compromised myocardial contractility due to halothane anesthesia and chronic low-dose beta blocker therapy.

Aged↗
PubMed1983

Comparison of isoflurane and halothane when used to control intraoperative hypertension in patients undergoing coronary artery bypass surgery.

The hemodynamic effects of isoflurane and halothane when used to control intraoperative hypertension were evaluated in 20 patients undergoing coronary artery bypass grafting. The patients were anesthetized with flunitrazepam, fentanyl, pancuronium, and N2O-O2. Control measurements were made after skin incision. When mean arterial pressure increased to 110 mm Hg due to sternal spread or surgical manipulation of the aorta, isoflurane or halothane were used to return arterial pressure to control levels. Using a non-rebreathing system, inspired isoflurane concentrations of 1.5-2.0 vol% or halothane concentrations of 1.0-1.5 vol% were necessary. Measurements were repeated during the hypertensive episode and after treatment with isoflurane or halothane while surgical stimulation continued. Both inhalation anesthetics decreased arterial pressure to baseline values within 5-10 min. The lowering of arterial pressure with halothane was not accompanied by significant decreases in the elevated systemic vascular resistance and pulmonary capillary wedge pressure. Cardiac index and stroke volume index decreased markedly when halothane was used (18% and 25%, respectively). In contrast, isoflurane significantly decreased systemic vascular resistance (42%). This reduction of left ventricular afterload was associated with an increase in cardiac index (22%) and a decrease in left ventricular filling pressure. Heart rate did not change significantly. These findings indicate that isoflurane is superior to halothane for controlling intraoperative hypertension during coronary artery bypass surgery.

Adult↗
PubMed1983

[Cyanosis as a result of drug-induced methemoglobinemia. A case report].

A 39-old, anaemic woman, admitted to hospital because of a fistula between bladder and bowel, developed a moderate degree of methaemoglobinaemia (19% of total haemoglobin) after prescription of 3 X 200 mg/die phenazopyridine (Pyridium) for 4 weeks. She showed a greyish discoloration of the skin; lips and nailbeds were cyanosed. On the basis of a glucose-6ph-dehydrogenase deficiency (71 mU/10(9) RBCs instead of 131 +/- 13 mU/10(9) RBCs - the normal value for adults) the medication with phenazopyridine induced methaemoglobinaemia. The coincidence of anaemia (8.7 g/dl Hb) and methaemoglobinaemia (19%) caused mild signs of hypoxia (fatigue, headache, feebleness and dyspnoea on exertion).

Adult↗
PubMed1982

Haemodynamic responses to induction of anaesthesia using midazolam in cardiac surgical patients.

The cardiovascular effects of midazolam 0.2 mg kg-1 i.v. were studied during the induction of anaesthesia in 16 premedicated patients subjected to cardiac surgery. In eight patients with coronary artery disease in whom global resting left ventricular function was normal the haemodynamic changes were small and observations on arterial pressure, cardiac index, stroke index, cardiac filling pressures, systemic and pulmonary vascular resistance appeared to parallel those accompanying deep sleep in healthy volunteers. In eight patients with valvular heart disease and haemodynamic evidence of moderately impaired cardiac performance, pump function during induction with midazolam was maintained, probably as a result of the tendency towards a decrease in systemic vascular resistance. Midazolam appears to be a valuable alternative to conventional induction agents without adverse effects on the cardiovascular system.

Adult↗
PubMed1982

Pulmonary vascular responses to nitrous oxide in patients with normal and high pulmonary vascular resistance.

The pulmonary vascular responses to 50 per cent nitrous oxide were studied in 32 anesthetized patients ventilated to maintain normal PaCO2. One group consisted of sixteen patients with coronary artery disease (CAD) and normal pulmonary vascular resistance (PVR) about to undergo coronary artery bypass surgery. A second group consisted of 16 patients with markedly elevated PVR values due to chronic mitral valve stenosis (MVS). CAD patients showed a significant increase in PVR irrespective of whether halothane or fentanyl was used as background anesthetic. Individual changes, however, did not exceed the upper limit of normal and therefore are not considered to be of clinical importance in these patients. In patients with MVS subjected to fentanyl anesthesia, N2O caused a marked increase in PVR from 357 to 530 dyn . s. cm-5. Halothane anesthesia did not significantly attenuate the effect of nitrous oxide on the pulmonary vasculature as mean PVR increased from 351 to 451 dyn . s. cm-5. These results suggest that the preexisting PVR value is of more importance for the pulmonary vascular response to N2O than the influence of background anesthesia. We conclude that nitrous oxide should be used with caution in patients with elevated pulmonary vascular resistance, particularly in the presence of right ventricular dysfunction and/or right coronary artery disease.

Coronary Disease↗
PubMed1982

[Hemodynamic analysis of 6 different anesthesia induction procedures in coronary surgery patients].

We investigated the cardiovascular effects of intravenous thiopentone (3.0 mg/kg), etomidate (0.3 mg/kg), althesin (0.07 ml/kg), ketamine (1.5 mg/kg), diazepam (0.15 mg/kg) and flunitrazepam (0.015 mg/kg) alone and after the addition of fentanyl (0.01 mg/kg) during induction of anaesthesia in 46 premedicated patients subjected to coronary artery bypass surgery. Thiopentone, etomidate or diazepam caused only small changes in the haemodynamic determinants of myocardial oxygen supply and demand (arterial pressure, heart rate, left and right ventricular filling pressure) in patients with coronary artery disease in whom global resting left ventricular function was normal. Althesin and flunitrazepam produced a significant fall in arterial pressure, cardiac index and stroke index; heart rate increased after the administration of althesin. Ketamine markedly elevated systemic and pulmonary pressure, heart rate, systemic and pulmonary vascular resistance, right and left ventricular filling pressure. The subsequent administration of fentanyl was associated with a further decrease in arterial pressure in the althesin and flunitrazepam group. The circulatory stimulating effects of ketamine were largely abolished by fentanyl. None of the induction procedures was associated with cardiovascular stimulation during laryngoscopy and tracheal intubation.

Alfaxalone Alfadolone Mixture↗
PubMed1982

[The influence of pressure loading upon haemodynamics and myocardial metabolism during beta-adrenoreceptor blockade (author's transl)].

This study compares the effects of a primary increase in afterload (induced by angiotensin) upon haemodynamics, myocardial function and metabolism of anaesthetized, closed chest dogs with (n = 7) and without (n = 7) beta-adrenoreceptor blockade. In both groups cardiac index (-20%) and stroke index (-30 resp. 40%) decreased by afterload increase. Pressure loading and beta-adrenoreceptor blockade were associated with a higher left ventricular enddiastolic pressure (+60%) and a higher heart rate (+35%) than in the control group. The high left ventricular enddiastolic pressure is supposed to be induced by the loss of homoiometric autoregulation. The increase in heart rate is due to the Bainbridge reflex. In the group of dogs with beta-adrenoreceptor blockade the myocardial oxygen consumption rose in proportion more than in the control group. The clinical implications are discussed.

Angiotensin II↗
PubMed1981

[Monitoring of cerebral electrical activity during cardiac surgery (author's transl)].

Continuous recording of cerebral activity by the Cerebral Function Monitor is a useful supplementation to anaesthetic monitoring in cardiac surgery. It is a simple and reliable method for early detection of cerebral damage during heart surgery and in other situations with possible cerebral impairment. The operating principles of the Cerebral Function Monitor and the interpretation of the electrical activity tracings are presented. Therapeutic considerations to minimize or to prevent anoxic brain damage are offered.

Age Factors↗
PubMed1981

[Systemic and coronary haemodynamic effects of dobutamine and norepinephrine during metabolic acidosis].

The effects of clinical doses of dobutamine (5 microgram/kg x min) and norepinephrine (0.2 microgram/kg x min) on systemic haemodynamics and coronary circulation were studied during normal pH and during metabolic acidosis (pH 7.0) induced by hydrochloric acid in 9 anaesthetized closed chest dogs. Metabolic acidosis per se failed to show any significant depression of cardiac function, indicating that animals with intact sympathoadrenal system are highly resistant to acidaemia. Our results further demonstrated that a significant circulatory response to clinical doses of dobutamine and norepinephrine was still present during metabolic acidosis. However, the increase in cardiac output, max dp/dt and mean arterial pressure after dobutamine was found to be significantly reduced at low pH-values, whereas the vasopressor response to norepinephrine was not affected. From these results it may be speculated that metabolic acidosis differently influences the responsiveness of alpha- and beta-adrenergic receptors. Finally our results show that metabolic acidosis did not compromise the coronary adjustment to catecholamine-induced increases in myocardial oxygen demand.

Acidosis↗