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Biomedical subjects

D M Payen

Publications and source records attributed to D M Payen.

30 records · Page 2Linked to original sources
PubMed1987

No involvement of antidiuretic hormone in acute antidiuresis during PEEP ventilation in humans.

Decreased urinary output (Vu ml/min) after institution of PEEP is attributed to a variety of mechanisms including decreased cardiac output and renal blood flow (RBF), activation of neurohormonal reflexes, increased catecholamines, plasma renin activity (PRA), and antidiuretic hormone (ADH) release. To evaluate these factors, seven normovolemic patients (36 yr +/- 13 SD), free of preexisting lung, cardiac, or renal disease, requiring continuous mandatory ventilation for neurologic reasons were studied. The authors measured or calculated: total blood volume (TBV) (51Cr); right atrial, pulmonary arterial, pulmonary wedge, and systemic pressures, cardiac index (CI); renal plasma flow (RPF) (iodohippurate sodium 131I [131I PAH] clearance); glomerular filtration rate (GFR) (creatinine clearance), free water clearance (CH2O), osmolal clearance (Cosm), fractional excretion of sodium (FENa+) and potassium (FEK+); and plasma renin activity (PRA) (ng X ml-1 X h-1), plasma ADH (pg/ml; radioimmunoassay), epinephrine (E in pg/ml), and norepinephrine (NE in pg/ml) (double-isotope radioenzymatic assay). Two conditions were studied after 90-min steady state: 1) zero PEEP (ZEEP); and 2) 15 cmH2O PEEP. PEEP caused a significant decrease in CI (-21%; P less than 0.01) and RPF (-19%; P less than 0.05) without significant decrease in GFR. A significant decrease in Vu (-55%; P less than 0.05), FENa+ (-39%; P less than 0.05) and Cosm (-36%; P less than 0.25) occurred without modification in CH2O. Plasma ADH remained in the normal range and did not increase when PEEP was applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗
PubMed1987

Hemodynamic, gas exchange, and hormonal consequences of LBPP during PEEP ventilation.

Hemodynamic, gas exchange, and hormonal response induced by application of a 25- to 40-mmHg lower body positive pressure (LBPP), during positive end-expiratory pressure (PEEP; 14 +/- 2.5 cmH2O) were studied in nine patients with acute respiratory failure. Compared with PEEP alone, LBPP increased cardiac index (CI) from 3.57 to 4.76 l X min-1 X m-2 (P less than 0.001) in relation to changes in right atrial pressure (RAP) (11 to 16 mmHg; P less than 0.01). Cardiopulmonary blood volume (CPBV) measured in five patients increased during LBPP from 546 +/- 126 to 664 +/- 150 ml (P less than 0.01), with a positive linear relationship between changes in RAP and CPBV (r = 0.88; P less than 0.001). Venous admixture (Qva/QT) decreased with PEEP from 24 to 16% (P less than 0.001) but did not change with LBPP despite the large increase in CI, leading to a marked O2 availability increase (P less than 0.001). Although PEEP induced a significant rise in plasma norepinephrine level (NE) (from 838 +/- 97 to 1008 +/- 139 pg/ml; P less than 0.05), NE was significantly decreased by LBPP to control level (from 1,008 +/- 139 to 794 +/- 124 pg/ml; P less than 0.003). Plasma epinephrine levels were not influenced by PEEP or LBPP. Changes of plasma renin activity (PRA) paralleled those of NE. No change in plasma arginine vasopressin (AVP) was recorded. We concluded that LBPP increases venous return and CPBV and counteracts hemodynamic effects of PEEP ventilation, without significant change in Qva/QT. Mechanical ventilation with PEEP stimulates sympathetic activity and PRA apparently by a reflex neuronal mechanism, at least partially inhibited by the loading of cardiopulmonary low-pressure reflex and high-pressure baroreflex. Finally, AVP does not appear to be involved in the acute cardiovascular adaptation to PEEP.

Adult↗
PubMed1986

[Noninvasive determination of stroke volume with impulse Doppler echocardiography: comparison with the Fick method].

Pulsed Doppler echocardiographic studies were performed in 14 patients (eleven with mitral valve disease, two with coronary artery disease, one with aortic and mitral valve replacement) for determination of cardiac output and the results compared with those obtained from simultaneous measurements carried out according to the Fick principle. Determination of cardiac output and stroke volume was achieved with a pulsed Doppler instrument specifically designed in our laboratory (repetition frequency 10 kHz, maximal penetrance 7.7 cm, ultrasonic beam diameter 3 cm at a distance of 5 cm from the transducer). Doppler measurements of the instantaneous blood flow velocity in the ascending aorta were obtained with the transducer in a suprasternal position. Through integration of the mean spatial velocity over an entire cardiac cycle, the distance traversed by the blood during one heart beat was obtained and then multiplied by the echocardiographically-determined cross-section area of the aorta and the heart rate to yield the cardiac output. There was a statistically-significant linear correlation between the cardiac output determined by Doppler (CO-D) and Fick (CO-F): CO-D = 0.92 CO-F X 0.48, r = 0.85, n = 14. The mean values for the two methods were 3.89 and 3.68 1/min, respectively. The correlation between the two methods improved if only those patients with sinus rhythm were taken into consideration (CO-D = 1.05 CO-F - 0.21, r = 0.93, n = 11). The results show that the pulsed Doppler method used enables accurate determination of cardiac output. The method can be carried out in all patients without aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Sustained ventricular unloading action of the alpha-adrenergic antagonist nicergoline in the dog.

Preliminary studies indicate that nicergoline, a new alpha-antagonist, can lower HR at doses which decrease arterial BP. The present animal study was designed to quantitate the systemic and carotid (pulsed Doppler) hemodynamic and renin release consequences of nicergoline ventricular unloading, and to investigate the hemodynamic mechanisms of hypotension. In 11 anesthetized dogs, nicergoline infusion induced progressive, moderate, and prolonged hypotension associated with reduced vascular resistance and capacitance. Hypotension resulted from decreased HR and cardiac output, without an increase in plasma renin activity. The effects on carotid hemodynamics were less marked than those on the systemic circulation. Hypotension was caused primarily by vasoplegia, and was magnified subsequently by inhibition of the reflex rapid pressor control mechanisms. This suggests that repeated iv doses of nicergoline are preferable to prolonged infusion.

Animals↗
PubMed1985

Lower body positive pressure vs. dopamine during PEEP in humans.

The application of lower body positive pressure (LBPP) of approximately 40 Torr was used to increase cardiac index (CI) in eight patients with acute respiratory failure (ARF) during positive end-expiratory pressure (PEEP) ventilation. The effects of LBPP on hemodynamics and gas exchange were compared with those of dopamine at the same level of CI without blood volume expansion. LBPP increased CI via an increase in stroke index without associated tachycardia, whereas dopamine combined both effects. A positive linear relationship (r = 0.82) was evidenced between CI and right atrial pressure (Pra) during application of LBPP according to the Frank-Starling mechanism, whereas dopamine did not increase Pra. The increase in CI with dopamine was associated with a significant rise in venous admixture (r = 0.84, P less than 0.001), whereas no such effect was observed with LBPP (r = 0.088). Changes in venous admixture were directly related to changes in mixed venous O2 pressure (PVO2) in both situations (r = 0.733, P less than 0.01), but the increase in PVO2 was more pronounced with dopamine than with LBPP (P less than 0.04). We conclude that LBPP can effectively counterbalance peripheral venous blood pooling during PEEP ventilation in humans with ARF and that changes in PVO2 appear as a major determinant of venous admixture in this setting.

Acute Disease↗
PubMed1984

Common carotid haemodynamic and metabolic effects of acutely administered nifedipine in human subarachnoid haemorrhage.

Although the drugs known as "calcium antagonists" exert inhibitory actions on vascular smooth muscle, there are no quantitative data concerning the clinical use of these vasodilator agents in human subarachnoid haemorrhage. In the present clinical study, we have measured the effects of nifedipine (20 mg tablet) on common carotid artery diameter (D) blood flow velocity (V) common carotid blood flow (CCBF) as an index of cerebral blood flow, systolic (Qs) and diastolic (Qd) blood flow fractions using a pulsed Doppler apparatus and on carotid arterial pressure (CAP), heart rate (HR) and oxygen consumption (VO2). Eight patients with subarachnoid haemorrhage were studied during anaesthesia for cerebral angiography. Thirty minutes after sublingual nifedipine, diameter (P less than 0.05), blood flow velocity (P less than 0.001), CCBF (P less than 0.001), Qs (P less than 0.05), and Qd (P less than 0.05) increased with a decrease in Qs/Qd ratio (P less than 0.05). carotid vascular resistance (CVR) fell (P less than 0.02) and oxygen consumption of the brain increased (P less than 0.01). Systolic, diastolic, and mean carotid blood pressure, heart rate, and arteriovenous difference in oxygen were unchanged. The increase in CCBF was closely correlated with the vascular resistance in the control state (r = 0.928, P less than 0.001) and with oxygen consumption (r = 0.869, P less than 0.001). We conclude that in vivo, nifedipine exerts a preferential action on cerebral vessels, vasodilating large arteries and arterioles. This action is more powerful if the vessels are already vasoconstricted. Thus, the use of nifedipine could be fruitful in cerebral ischaemia that is secondary to subarachnoid haemorrhage.

Adult↗
PubMed1984

Effects of nifedipine on pulmonary arterial hypertension in patients with respiratory insufficiency without acute failure.

Permanent pulmonary arterial hypertension is a standard part of the prognosis for patients with chronic respiratory insufficiency. As a decrease of pulmonary arterial hypoxic vasoconstriction may be obtained by calcium antagonists, we studied the effects of nifedipine (10 mg sublingually) in 10 patients with chronic respiratory insufficiency without acute respiratory failure. Our results show that maximal expiratory air flow was not altered. The pulmonary antihypertensive action of this drug, which is less effective than oxygen breathing at low concentration, was associated with a constant decrease of arterial oxygen partial pressure; the oxygen transport was not sustained for every patient. This result suggests that considerable caution should be exercised in using this drug for the treatment of pulmonary arterial hypertension in patients with chronic respiratory insufficiency without acute failure.

Aged↗
PubMed1984

Systemic and carotid haemodynamics and plasma renin activity during deliberate hypotension in dogs: a comparison of sodium nitroprusside with nicergoline.

This study was designed to compare at the same level of hypotension (-30%) nitroprusside (SNP) and nicergoline (NIC) effects on systemic haemodynamics and carotid haemodynamics (pulsed Doppler) and on plasma renin activity (PRA) in 20 anaesthetized dogs before and at the 20th minute of hypotension. In SNP group (n = 9) cardiac output (CO) and heart rate (HR) increased. Stroke volume (SV), pulmonary wedge pressure (PWP), central venous pressure (CVP) and systemic vascular resistance (SVR) decreased. Common carotid diameter (D) increased and blood flow velocity (V) decreased with constant common carotid blood flow (CCBF). CCBF/CO ratio was unchanged. PRA levels increased. In NIC group (n = II), HR, CO, SV were unchanged and PWP, CVP, SVR decreased. D, V and CCBF were unchanged. CCBF/CO ratio increased and PRA was unchanged. NIC provoked mild hypotension without reflex sympathetic activation unlike SNP. Only SNP dilated large arteries. The autoregulation of CCBF is maintained with both drugs but CCBF/CO ratio is increased only with NIC.

Anesthesia↗
PubMed1982

Prospective study of predictive factors determining borderline hypertensive individuals who develop sustained hypertension: prognostic value of increased diastolic orthostatic blood pressure tilt-test response and subsequent weight gain.

Repeat hemodynamic determinations in supine and tilting positions were performed in 23 young men with borderline hypertension (HBP). The mean duration of follow-up was 48 months. During the study 11 patients had no change in hemodynamic parameters (group II), while 12 patients exhibited significant increase in systolic (p less than 0.001) and mean (p less than 0.01) arterial pressures (BP) and in body weight (p less than 0.05) (group I). In this latter group, the initial hemodynamic pattern included supine elevations in cardiac output (CO) and heart rate (HR) and significant increase in diastolic orthostatic BP. After follow-up, the group I primary supine increases in CO and HR were followed by secondary supine increases in total peripheral resistance (p less than 0.01) and systolic (p less than 0.001) and mean (p less than 0.01) BP with lower CO (p less than 0.05) and HR (p less than 0.001). In addition, it was shown during long-term follow-up in group I patients that : (1) the increase in systolic BP per unit age was negatively correlated with initial age (p less than 0.001), (2) the increase in BP was positively correlated with weight gain (p less than 0.05), and (3) the diastolic orthostatic hypertension disappeared. This study provides evidence that, in patients with borderline HBP having supine elevations of CO and HR, the subsequent development of sustained HBP can be expected, with follow-up observation of lower supine HR and disappearance of diastolic orthostatic hypertension accompanied by rapid weight gain.

Adult↗
PubMedDate not supplied

Non-invasive ultrasonic cardiac output measurement in intensive care unit.

A non-invasive method for measuring cardiac output utilizing M-mode echography and pulsed Doppler ultrasound is described. Measurements were obtained in 26 of 29 randomly selected, mechanically ventilated patients. These values were compared with simultaneously measured cardiac outputs by thermodilution. There was a statistically significant linear relationship between Cardiac Output measured by Doppler (DCO) and Thermodilution (TDCO): DCO = 0.86 TDCO + 0.29 l/min (r = 0.96, n = 26, SEE = 0.45 l/min) over the range of 1.75-8.5 l/min. DCO had the additional advantage of measuring peak flow velocity and maximal blood flow acceleration during early systole, indices of left ventricular pumping ability. Ultrasonic monitoring of cardiac output may be an important supplement to invasive methods in critical care.

Adult↗
PubMedDate not supplied

Evaluation of human hemispheric blood flow based on non invasive carotid blood flow measurements using the range-gated Doppler technique.

Common carotid blood flow (CCBF) was measured in 11 anesthetised patients without extracranial arterial disease (nine acute subarachnoid haemorrhages and two cases of head injury). The range-gated Doppler flowmeter with an adjustable range-gated time system and a double transducer probe was used to determine diameter, blood velocity, and blood flow of the common carotid artery. Values were, respectively, 5.9 +/- 1.1 mm, 13.8 +/- 6.1 cm . sec-1 and 387 +/- 183 cm3 . min-1. Mean cerebral blood flow (rCBF) measurements were simultaneously made by 133Xenon intra-arterial method, with a value of 22.28 +/- 5.96 ml . min-1 . 100 g. High correlation coefficient was found between CCBF and mean rCBF (r = 0.73, p less than 0.001). The range-gated Doppler flowmeter thus provides a non invasive and easily duplicated method for monitoring cerebral blood flow in anesthetized patients.

Adult↗