Cardiovascular control mechanisms during anesthesia.
Explore the source record for details and available documents.
Anesthesia↗
Biomedical subjects
J Marty
Publications and source records attributed to J Marty.
Effects of propofol on baroreflex control of heart rate and on plasma noradrenaline levels.
The effects of propofol induction (2.5 mg kg-1) and of two continuous infusion rates of propofol (100 and 200 micrograms kg-1 min-1) on baroreflex control of heart rate and on plasma noradrenaline concentration were investigated in 11 unpremedicated patients. Baroreflex function was assessed using a pressor test (phenylephrine) and a depressor test (sodium nitroprusside). In addition, samples for subsequent determination of plasma noradrenaline levels and blood propofol levels were collected before each test. Baroreflex sensitivity and plasma noradrenaline concentrations were not significantly changed at any time of the study. By contrast, a significant and sustained resetting of baroreflex set point was observed, allowing unchanged heart rate at lower arterial pressure. It is concluded that the effects of propofol on baroreflex function and noradrenaline concentration are moderate.
Adult↗
[Prevention of per- and postoperative myocardial ischemia in non-cardiac surgery by intravenous diltiazem].
A controlled double-blind trial was carried out to assess the efficacy and safety of a continuous intravenous infusion of diltiazem in preventing perioperative myocardial ischaemia in patients with coronary artery disease. Sixty-six patients undergoing non cardiac surgical procedures (vascular surgery, n = 37; other, n = 29) were randomly chosen to receive either diltiazem (group D, n = 32); or placebo (group P, n = 34); there was no difference between these groups in the number of patients in each NYHA class (I: 13/16; II: 14/14; III: 5/4) or having had a previous myocardial infarct (20/22). ECG leads CM5 and CL5 were recorded continuously with an ICR 7200 Holter monitor. After starting recording, either placebo or a loading dose (0.5 mg.kg-1) of diltiazem was given, followed by an infusion of 5 micrograms.kg-1.min-1. Anaesthesia was induced by thiopentone and suxamethonium, and maintained with nitrous oxide (50%), fentanyl and either halothane or droperidol. The number of myocardial ischaemic episodes was significantly (p less than 0.05) lower in group D (2 ST depressions in two patients) than in group P (8 ST depressions in six patients, 2 myocardial infarcts and 1 pulmonary oedema). No conduction disturbance was observed; the lowest cardiac frequency was found in group P (32 b.min-1). Systolic and diastolic arterial blood pressures were lower in group D than in group P, but no difference was found in heart rate and rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Haemodynamic responses following reversal of benzodiazepine-induced anaesthesia or sedation with flumazenil.
Explore the source record for details and available documents.
Anesthesia↗
[Orodental care in long-term geriatric facilities].
Explore the source record for details and available documents.
Aged↗
[Effects of flunitrazepam on the baroreflex control of heart rate and on adrenergic activity].
The effects of intravenous flunitrazepam (25 micrograms . kg-1) on the baroreflex control of heart rate and plasma catecholamine levels were determined in ten ASA 1 unpremedicated patients. Plasma concentrations of flunitrazepam were also measured. The data was obtained before and 5, 10 and 15 min after flunitrazepam administration. The baroreflex gain was significantly decreased at 5 min, the time of the highest flunitrazepam plasma concentration. Catecholamine plasma levels were decreased at each study time. It was concluded that flunitrazepam induced a transient depression in baroreflex function and a sustained decrease in adrenergic activity.
Adult↗
Effects of droperidol on sympathetic activity and baroreflex control of heart rate in humans.
The effects of intravenous droperidol, 0.2 mg . kg-1, on baroreflex control of heart rate and on plasma catecholamine levels were determined in 10 ASA physical status I unpremedicated patients. Baroreflex control of heart rate was assessed by a pressor test using phenylephrine. Plasma concentrations of norepinephrine and epinephrine were determined by high pressure liquid chromatography, and plasma droperidol concentrations were measured by radioimmunoassay, from blood samples withdrawn before baroreflex evaluation. All data were obtained before and 5, 10, and 15 min following droperidol administration. Baroreflex response was significantly decreased after droperidol at each time of the study with the maximal decrease (-47% from control) observed at 5 min. No resetting of baroreflex was present since the pulse interval at the reference pressure was unchanged. Plasma norepinephrine concentrations were moderately but significantly increased only at 5 min, while no significant change in epinephrine concentrations was observed. It is concluded that droperidol induces a moderate but sustained alteration of baroreflex function and a transient increase in plasma norepinephrine concentrations.
Adult↗
The effects of halothane on the human beta-adrenergic receptor of lymphocyte membranes.
The effects of halothane on beta-adrenergic receptor antagonist interaction were studied using the membranes of human lymphocytes as a model. Membrane preparations of lymphocytes were obtained from blood samples withdrawn from seven healthy young volunteers. Beta-receptor studies were performed using (-)125I iodocyanopindolol (125ICP) binding. Non-specific binding was determined in the presence of (-)isoproterenol. Beta-receptor density (Bmax) and the dissociation constant (KD) for 125ICP were determined from saturation curves. Beta-receptor affinity for agonists evaluated by the IC50 (the concentration of isoproterenol required to inhibit 50% of specific 125ICP binding) and the dissociation constant (KL) for isoproterenol was established from competition curves. The effect of halothane 1%, in an air oxygen mixture (oxygen fraction: 0.3) administered by tonometry during ligand membrane incubation, on beta-adrenergic receptor, was compared to that of control experiments not exposed to halothane. Halothane produced a moderate but significant decrease of Bmax (-10%) and a significant increase in non-specific binding (+30%), while KD, IC50, and KL were unchanged. The authors conclude that halothane, in vitro, decreases beta-adrenergic receptor density. This effect could be mediated by an alteration of the receptor in the membrane due to action of halothane on the lipid phase of the membrane.
Adult↗
Effects of droperidol on peripheral vasculature: use of cardiopulmonary bypass as a study model.
The effects of droperidol on the systemic vascular resistance (SVR) and the venous capacitance were studied during cardiopulmonary bypass (CPB) in 24 patients. CPB was performed with either pulsatile or non-pulsatile flow. During non-pulsatile flow, droperidol (0.15 mg X kg-1 and 0.30 mg X kg-1) decreased SVR and increased venous capacitance. These values were significantly different after the 2nd and the 7th min, respectively. During pulsatile flow, the initial SVR was lower. The decremental effect of 0.30 mg X kg-1 droperidol on SVR was proportional to the preinjection level of SVR (r = 0.64). The increase in venous capacitance related to droperidol was independent of the dose and of the type of flow in all patients. It can be concluded that the vasodilating action of droperidol during CPB on the arterial bed is transient, independent of dose, and related to the preinjection level of SVR. The effect of droperidol on venous capacitance is not as rapid but has a longer duration.
Blood Vessels↗
Effects of midazolam on the coronary circulation in patients with coronary artery disease.
The effects of midazolam on coronary sinus blood flow (CSBF), myocardial oxygen consumption (MVO2), and myocardial lactate balance were investigated in eight patients with stable coronary artery disease undergoing cardiac catheterization. Coronary sinus blood flow was measured by continuous thermodilution. Arterial and coronary sinus blood were analyzed for oxygen and lactate content. The determinants of left ventricular (LV) performance were obtained from the cardiac output measured by thermodilution and from left heart catheterization data. All data were obtained before, and 5 and 15 min after midazolam, 0.2 mg X kg-1 iv. Sleep was induced in all patients after administration of midazolam and persisted throughout the entire study period. Mean aortic and LV end-diastolic pressure were decreased from control values (-15 and -44%, respectively), as well as cardiac index and stroke index (-10 and -15%, respectively). Heart rate increased moderately (+8%), while no change in systemic vascular resistance and maximum velocity of shortening (Vmax) were observed. Midazolam administration was followed by a decrease of CSBF (-24%) and of MVO2 (-26%). Coronary vascular resistance did not change, but coronary sinus oxygen tension increased slightly, suggesting a mild alteration in normal autoregulation. However, no evidence of myocardial ischemia occurred, as judged by the absence of changes in the: 1) ECG, 2) myocardial lactate extraction, and 3) relaxation time constant. These results suggest that midazolam may be used safely in patients with coronary artery disease.
Anesthesia↗
Effects of diazepam and midazolam on baroreflex control of heart rate and on sympathetic activity in humans.
The effects of induction of anesthesia with diazepam and midazolam on baroreflex control of heart rate and on plasma levels of catecholamines were investigated in this study. Group 1 subjects (n = 10) received diazepam, 0.4 mg/kg. Group 2 subjects (n = 10) received midazolam, 0.3 mg/kg. Baroreflex function was assessed using a pressor test (phenylephrine). In addition, samples for subsequent determination of plasma norepinephrine and epinephrine levels and plasma diazepam or midazolam concentrations were collected before and 5, 10, and 15 min after intravenous drug administration. The pressor baroreflex slope declined significantly after diazepam or midazolam administration with the maximal changes (-45 and -43%, respectively) observed when plasma diazepam or midazolam concentrations were the highest. Norepinephrine plasma concentrations decreased at each measurement with both drugs. In contrast, epinephrine concentration decreased only after midazolam. The authors conclude that diazepam or midazolam used for induction of anesthesia results in a transient depression of baroreflex function and a sustained decrease of sympathetic tone. This study also indicates that the depression of arterial baroreflex heart rate responses under diazepam or midazolam anesthesia are less pronounced than the depression of baroreflex responses reported by other investigators with potent inhalational anesthetics. However, this disruptive effect of diazepam and midazolam on sympathetic control of circulation might induce a limited ability to compensate for hemodynamic alterations related to hypovolemia.
Adult↗
The bone marrow biopsy: a diagnostic strategy.
Explore the source record for details and available documents.
Biopsy↗
[Computerization of pain treatment].
Explore the source record for details and available documents.
Analgesics, Opioid↗
Alfentanil pharmacokinetics in patients with cirrhosis.
The pharmacokinetics of alfentanil were studied in 11 patients with alcoholic cirrhosis and 10 control patients during general anesthesia. All patients received 50 micrograms . kg-1 alfentanil as an intravenous bolus injection. Plasma concentrations were measured at intervals up to 10 h, using a specific radioimmunoassay technique. Protein binding was measured by equilibrium dialysis. Patients with cirrhosis had a significantly lower (P less than 0.01) plasma clearance of alfentanil of 1.6 +/- 1.0 ml . min-1 . kg-1 (mean +/- SD) instead of 3.1 +/- 1.6 ml . min-1 . kg-1 in the controls. The total apparent volume of distribution was similar in the two groups. The elimination half-life was prolonged from 90 +/- 18 min in the controls to 219 +/- 128 min in the cirrhotics (P less than 0.01). Patients with cirrhosis had a higher (P less than 0.01) alfentanil plasma-free fraction (18.6 +/- 9.4%) compared with the control patients (11.5 +/- 3.9%). When kinetic parameters were corrected for protein binding, the unbound volume of distribution and the free drug clearance were decreased significantly in patients with cirrhosis. Since the concentration alpha 1-glycoprotein to which alfentanil mainly is bound in plasma did not differ in the two groups, it is suggested that the increase in the free fraction is caused by an alteration of binding sites of this protein in patients with cirrhosis. Owing to its delayed elimination and increased free fraction, alfentanil will exert a prolonged and pronounced effect in patients with cirrhosis.
Adult↗
Neural induction: embryonic determination elicits full expression of specific neuronal traits.
In Pleurodeles waltl, the early neuronal differentiation of precursor cells from late gastrula stage has been studied by culture in vitro from either isolated neural plate (NP) or isolated neural fold (NF). The aim of this study was to delineate the information acquired by ectodermal target cells during neural induction. By culturing these cells in vitro either with or without the underlying chordamesoderm, we showed that in the absence of chordamesodermal influence such NP or NF cells exhibited a high degree of biochemical and morphological differentiation as revealed by the synthesis and the storage of neurotransmitters, the activity of specific enzymes, as well as by the expression of neuronal markers: specific changes in cell surface carbohydrates, tetanus toxin binding sites and neurofilament polypeptides. Remarkable changes in the cell adhesive properties were the first events observed in the different central (NP) and peripheral (NF) types. In cocultures the chordamesodermal cells exert a beneficial influence on this differentiation, specially increasing acetylcholine synthesis. There are some differences between central (NP) or peripheral (NF) neuroblast response to this further notochord or mesodermal influence.
Acetylcholine↗
Use of immunologic tumor markers in body fluid analysis.
Sensitive and specific tumor markers will increase the accuracy of present cytologic techniques and will teach us more about the biology and pathogenesis of tumors. Immunoenzyme studies may also be useful in quality control and may accelerate the development of automated screening techniques for cytology.
Alkaline Phosphatase↗
Hypertensive responses during operation for phaeochromocytoma: a study of plasma catecholamine and haemodynamic changes.
Virtually all patients undergoing resection of a phaeochromocytoma exhibit hypertensive crises at some period perioperatively. In order to study the events associated with hypertensive responses, cardiovascular variables were measured with a Swan-Ganz pulmonary artery catheter and plasma catecholamine levels were determined simultaneously in eight patients during surgery for phaeochromocytoma. Hypertensive responses requiring vasodilator treatment occurred in five patients, i.e. systolic blood pressure (BP) greater than 200 mmHg for more than 1 min. Transient elevation, at least in systolic BP, to greater than 200 mmHg occurred in all patients. Hypertensive responses were identified associated with two circumstances: the first in association with noxious stimuli, i.e. intubation, skin incision, etc., but were not generally accompanied by an elevation in plasma noradrenaline and adrenaline levels; the second occurring during tumour manipulation were more severe and were always accompanied by elevated plasma noradrenaline and adrenaline levels. Transient left ventricular dysfunction, defined by increased pulmonary capillary wedge pressure (PCWP) and decreased cardiac index (CI) secondary to a marked increase in systemic vascular resistance (SVR), was observed in four patients during palpation of the tumour, while one patient exhibited more marked and prolonged ventricular dysfunction. It is concluded that hypertensive responses associated with noxious stimuli may be controlled with deep anaesthesia while those due to tumour manipulation cannot be prevented and are best treated with vasodilators.
Adrenal Gland Neoplasms↗
Absorption and metabolism of butyric acid in rabbit hind gut.
Butyrate absorption in the large intestine of the rabbit was evaluated by the variation of concentrations in the bowel, the arterio-venous plasma and the intestinal loops. The metabolic transformations were studied with (3-4 C14) butyrate. The caeco-colonic epithelium oxidized negligible quantities of butyrate to ketone bodies and other metabolic pathways were found. These pathways were of different intensity according to the region of the gut and both phases of the excretory cycle. A portion, which may be large, was metabolized in the caeco-colonic wall and in the liver where radioactivity was found in free amino acids, carboxylic acids and sugars. The oxidation to CO2 in TCA cycle yields energy for metabolic activities. This study of metabolism takes account of the endoflora participation.
Absorption↗