Search PubMed⌕ Search

Biomedical subjects

G Annat

Publications and source records attributed to G Annat.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Peranesthetic monitoring of ventilation in children: value of capnometry].

Continuous measurement of the end-expiratory partial pressure of carbon dioxide (PETCO2) during anaesthesia has been proposed for non-invasive monitoring of arterial PCO2 (PaCO2). The values and the stability of the difference (PaCO2-PETCO2) during anaesthesia were studied for two ventilatory settings in eight children with healthy lungs and normal cardiac function undergoing minor surgery. PaCO2 values were all within a physiological range (30.2-43.6 mmHg). PaCO2-PETCO2 values ranged from 0.2 to 9.9 mmHg. With either mode of ventilation, there was no significant variation in PaCO2-PETCO2. It is concluded that estimation of PaCO2 was reliable during anaesthesia when haemodynamic and ventilatory states were stable, but a first determination of the PaCO2-PETCO2 gradient remained necessary for each child.

Anesthesia, General↗
PubMed1986

Pulmonary gas exchange during hemodialysis.

UNLABELLED: Pulmonary gas exchange was continuously measured in 13 mechanically ventilated patients during 24 hemodialyses for acute renal failure. Minute-ventilation was maintained constant by controlled ventilation and gas exchange was continuously measured by a mass-spectrometer system. Three groups were compared: a cuprophan membrane with an acetate dialysate; a polyacrilonitrile membrane (PAN) with an acetate dialysate; and PAN with a bicarbonate dialysate. Arterial PO2 and the O2 alveolar-arterial gradient were the same regardless of the membrane used. [H+] mildly decreased with all dialysates used. Arterial PCO2 decreased only with the acetate dialysate. O2 consumption increased, up to 20 +/- 5% of the initial values during hemodialysis, and remained increased during the two hours following the hemodialysis. Respiratory exchange ratio was lower after than before the hemodialysis. IN CONCLUSION: the maintenance of a constant minute ventilation prevented hemodialysis induced hypoxemia. VO2 increased during hemodialysis.

Acute Kidney Injury↗
PubMed1986

Arterial-alveolar oxygen partial pressure ratio: a theoretical reappraisal.

The relationship between the arterial-alveolar oxygen partial pressure ratio (PaO2/PAO2) and different fractions of inspired oxygen (FIO2) was studied using a bicompartmental computer model. PaO2/PAO2 was found to be less stable than in previous clinical works probably because the venous admixture varied with changes in the FIO2.

Blood Pressure↗
PubMed1986

Oxygen delivery and uptake in the adult respiratory distress syndrome. Lack of relationship when measured independently in patients with normal blood lactate concentrations.

This study was designed to determine whether acute alterations in oxygen delivery (DO2) induced by the institution of positive end-expiratory pressure (PEEP) would affect oxygen uptake (VO2) in patients with adult respiratory distress syndrome (ARDS). In 8 patients with ARDS who exhibited normal blood lactate concentrations, we evaluated the relationship between DO2 and VO2 during 3 consecutive periods: intermittent positive pressure ventilation (IPPV), continuous positive pressure ventilation (CPPV) with a 10 cm H2O PEEP, and finally CPPV with volume loading. Oxygen uptake was measured directly with a mass spectrometer system. Oxygen delivery was calculated as the product of cardiac output (thermodilution) and arterial blood oxygen content (Lex-O2-Con analyzer). By comparison with the IPPV period, application of PEEP led to a decrease of DO2, which returned to baseline values when volume loading was added to PEEP. In none of the patients did VO2 parallel the changes of DO2. They demonstrated, therefore, a properly enhanced oxygen extraction during the PEEP-induced decrease of DO2. We conclude that, when measured independently, DO2 and VO2 are not correlated in patients with ARDS with normal blood lactate who are mechanically ventilated with PEEP.

Adult↗
PubMed1985

Epinephrine, norepinephrine, and dopamine during a 4-day head-down bed rest.

Head-down bed rest at an angle of 6 degrees was used as an experimental model to simulate the hemodynamic effects of microgravity, i.e., the shift of fluids from the lower to the upper part of the body. The sympathoadrenal activity during acute (from 0.5 to 10 h) and prolonged (4 days) head-down bed rest was assessed in eight healthy men (24 +/- 1 yr) by measuring epinephrine (E), norepinephrine (NE), dopamine (DA), and methoxylated metabolite levels in their plasma and urine. Catecholamine (CA) and methoxyamine levels were essentially unaltered at any time of bed rest. Maximal changes in plasma were on the second day (D2): NE, 547 +/- 84 vs. 384 +/- 55 pg/ml; DA, 192 +/- 32 vs. 141 +/- 16 pg/ml; NS. After 24 h of bed rest, heart rate decreased from 71 +/- 1 to 63 +/- 3/min (P less than 0.01). Daily dynamic leg exercise [50% maximum O2 uptake (VO2 max)] used as a countermeasure did not alter the pattern of plasma CA during bed rest but resulted in a higher urinary NE excretion during postexercise recovery (+45% on D2; P less than 0.05). The data indicate no evident relationship between sympathoadrenal function and stimulation of cardiopulmonary receptors or neuroendocrine changes induced by central hypervolemia during head-down bed rest.

Adult↗
PubMed1983

Effect of PEEP ventilation on renal function, plasma renin, aldosterone, neurophysins and urinary ADH, and prostaglandins.

To explore the main factors which could be involved in the fluid retention induced by continuous positive pressure ventilation (CPPV), hemodynamics, renal, and hormonal parameters were measured in seven intensive care patients during three consecutive 60-min periods; one of intermittent positive pressure ventilation (IPPV), one of CPPV (PEEP 10 cmH2O), and finally one of IPPV. During CPPV, a 15% decrease in cardiac output was observed, without alteration in arterial pressure or right atrial transmural pressure. In addition, decreases were observed in urinary output by 34%, glomerular filtration rate by 19%, renal blood flow by 32%, sodium excretion by 33%, and potassium excretion by 26%. There was no change in the fractional excretion of sodium and free water. Institution of PEEP also led to a significant increase in plasma renin activity, plasma aldosterone, and urinary antidiuretic hormone, without significant variation in plasma neurophysins and urinary prostaglandins E and F alpha. All of the changes that occurred during CPPV were reversed when PEEP was withdrawn. It is concluded that the short-term antidiuretic effect of PEEP is mainly due to a hemodynamic impairment of renal function. The water- and sodium-retaining hormonal systems also are stimulated and could participate in the fluid retention during more prolonged respiratory support with PEEP.

Adolescent↗
PubMed1982

[The renin-angiotensin system and the sympathetic nervous system in essential hypertension].

In 112 patients with essential hypertension (HTA), free of any therapeutic and receiving the standard ward, a significant inverse relationship was found between age and plasma renin activity (PRA) and plasma aldosterone (PA), measured in the supine and upright position. Urinary epinephrine and norepinephrine were not related with age. When dividing the patients in 4 different age groups, it appeared that those younger than 30 years exhibited a significantly higher PRA and PA values and a higher frequency of borderline hypertension (45 p. 100) than the older ones (12 p. 100). So as to determine the characteristics associated with borderline HTA, it was necessary to eliminate the influence of age. This was achieved by comparing two groups of carefully age-matched patients, one with borderline HTA and the other with stable HTA. The only significant difference found was a significantly more marked increase in PRA in response to orthostatism, in patients with borderline HTA. Since renin responses to an orthostatic stress are largely mediated by renal nerves, this result suggest that borderline HTA could be associated with an increased reactivity of the sympathetic nervous system.

Adult↗
PubMed1981

Relationships between blood pressure and plasma renin, aldosterone and dopamine-beta--hydroxylase in the elderly. Studies in patients over 70 years of age.

Plasma renin activity (PRA), aldosterone (PA) and dopamine-beta-hydroxylase activity (DBH) were measured in 49 subjects over 70 years of age, selected for normal or high blood pressure level. By comparison with younger controls, elderly subjects exhibited lower supine or upright PRA, but similar PA and DBH. No relationship could be found between individual blood pressure, and PRA, PA or DBH. The data favor the view that the renin-angiotensin-aldosterone system does not play an important causative role in elderly hypertension. They also point to the necessity of age-matched controls when this system is being studied in elderly patients.

Aged↗
PubMed1981

A longitudinal study of plasma renin activity during normal and preeclamptic pregnancy.

In 68 pregnant women, blood samples were obtained at 12, 20, 25, 29, 32 and 36 weeks. Plasma renin activity (PRA) was measured in 10 of them, who developed "pregnancy induced hypertension" ("PIH") and in 10 normal pregnant women, matched with the hypertensive patients for age, parity and body weight. Towards the end of pregnancy, PRA showed a tendency to increase in the "PIH" group, and to decrease in the control group. However, these variations were not statistically significant. There was no significant difference between the two groups, except for the last measurement, obtained at the 36th week of gestation. At this time, PRA was more elevated in the PIH group. We conclude that PRA measurements early in pregnancy are of no value in predicting if women are going to develop PIH.

Female↗
PubMed1981

[Plasma renin activity (PRA) and aldosterone (PA) during submaximal exercise. Effect of training (author's transl)].

The effect of training on PRA, PA, hematocrit and weight loss was studied at rest and following an exercise performed until exhaustion. Two groups of subjects were used, the first, a group of 4 young well trained men (88.6% +/- 7.7 V02 max) and the second a group of 4 young untrained men (77.5% +/- 7 V02 max). PRA and PA displayed highly significant increases after exercise in both groups, but PRA resting values were lower in the well trained subjects (p less than 0.05). PRA values were also lower in the latter group after exercise, but the difference in this case was not significant. Further, the variation of hematocrit was less (p less than 0.05) and the weight loss greater in the well trained subjects. In an additional experiment, the same parameters were studied in four subjects submitted to a five month training programme (87% V02 max). Though resting values for PA remained unchanged after training, PRA resting values and PRA post exercise values were significantly lower. A comparison between the magnitude of weight loss and hematocrit variation showed that when untrained subjects became trained, the variation of hematocrit was smaller (p less than 0.05) while weight loss was larger (p less than 0.01). These observations could be explained in terms of the change in blood volume, and/or a decrease in sympathetic nervous activity induced by training.

Adult↗
PubMed1980

[Primary postural hypotension. Physiopathological study of 8 cases (author's transl)].

Physiological tests showed that both branches of the baroreflex arc-vagal cardiomoderator and, predominantly, sympathetic vasoconstrictor--were affected. There was no rise in serum and urinary noradrenaline levels in standing position, and adrenaline concentrations were rarely increased under induced hypoglycaemia. Dopamine beta-hydroxylase activity and reactivity of the renin-angiotensin-aldosterone system remained normal in most cases. Physiopathologically, the two clinical forms described (i.e. with and without central nervous symptoms) cannot be differentiated.

Aged↗
PubMed1980

Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men.

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.

Adult↗
PubMed1980

Plasma renin activity, aldosterone and dopamine beta-hydroxylase activity as a function of age in normal children.

In 149 children between 6 days and 15 years of age, plasma renin activity (PRA) and aldosterone (PA) were measured by radioimmunoassay and plasma dopamine beta hydroxylase activity (DBH) by the method of Nagatsu. PRA and PA decreased with age from 496 +/- 119 ng/1/min for PRA and 643 +/- 158 pg/ml for PA in 6 to 30 day-old newborns to 37.8 +/- 4.7 ng/1/min for PRA and 43. 1+/- 8.3 ph/ml for PA in 9 to 15 year-old children. DBH increased with age from less than detection limit values (< 2 IU) in 6 day to 3 month-old newborns to 17.2 +/- 5.1 IU in 9 to 15 year-old children. In addition a significant relationship was found between PRA and PA (log PA = 0.99 log PRA -0.058, r = 0.732, n = 104, p < 0.001) and PRA and DBH (log DBH = -0.41 log PRA +1.62, r = 0.404, n = 80, p < 0.001). These results demonstrate the opposite evolution of the Renin-Angiotensin-Aldosterone System and of the sympathoadrenal system during development.

Adolescent↗