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Biomedical subjects

R Marcelle

Publications and source records attributed to R Marcelle.

At least 37 records · Page 2Linked to original sources
PubMed1991

Use of PEEP in management of life-threatening status asthmaticus: a method for the recovery of appropriate ventilation-perfusion ratio.

In 15 patients with asthma attack, evidence of the uneven distribution of air flow during controlled ventilation was obtained by detection of ventilatory asynchronism expressed by the incurvated profile of tracheal pressure waves associated with the repetitive interruptions of air flow. It was observed that low values of PEEP (mean: 5 +/- 2.5 cm H 2O) induced an increase in transbronchial pressure able to overcome ventilatory asynchronism. In these conditions, an appropriate ventilation-perfusion ratio was restored and improved gas exchanges as indicated by the mean increase of arterial PO 2 from 66.3 mmHg (+/- 2.57) to 96.89 mmHg (+/- 4.41) (p = 0.0005) associated with a mean decrease in arterial PCO 2 from 53.66 mmHg (+/- 2.71) to 42.07 mmHg (+/- 1.64) (p = 0.0005). Simultaneously hemoglobin oxygen saturation rose from 82.31% (+/- 1.97%) to 95.74% (+/- 0.5%). In our patients, such values of PEEP were not high enough to influence the pulmonary arterial circulation. The means of the pulmonary arterial pressures obtained before (syst.: 32.3; diast.: 15.1; mean: 22.00 mmHg) were quite the same (p greater than 0.2) as with PEEP (syst.: 32.00; diast.: 14.00; mean: 21.1 mmHg). The mean of the wedge pressure was found to be 8.3 (+/- 74 mmHg) prior to and 8.4 (+/- 0.68 mmHg) after PEEP (p greater than 0.3). Mean cardiac output rose slightly from 5.27 l/min (+/- 0.24) to 5.77 l/min (+/- 0.38) during PEEP (p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Accuracy in early prediction of prognosis of patients with septic shock by analysis of simple indices: prospective study.

In 26 consecutive septic shock patients, we analyzed the clinical, hemodynamic, and metabolic data before and during volume infusion to test their circulatory reserve in response to fluid repletion. These patients were investigated to identify early variables that could predict outcome. There were 15 survivors (group A) and 11 nonsurvivors (group B). As a mean, group A patients were hemodynamically evaluated 2.3 h after onset of the sepsis syndrome, whereas group B patients underwent cardiac catheterization after a 12-h interval. At the initial evaluation, both groups demonstrated similarly decreased mean arterial pressure, mean heart rate, and mean cardiac filling pressure. Only group A patients evidenced elevated cardiac index (CI) (greater than 4 L/min.m2) associated with low systemic vascular resistance index (less than 7400 dyne.sec/cm5.m2), which is generally recognized as hyperdynamic cardiac state. However, none of the initial cardiovascular variables could serve as a predictor for survival. Fluid challenge increased left ventricular preload from 6 to 12.4 and from 7.8 to 12.7 mm Hg in group A and group B, respectively. The increases were associated with significant increases in CI from 4.4 to 6.9 and from 3 to 3.8 L/min.m2. However, at the end of fluid challenge, only group A patients exhibited normal cardiac response, as evidenced by the change in left ventricular stroke work index (LVSWI) for a given increase in the pulmonary capillary wedge pressure (WP) that was referred to as left cardiac preload.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Pathogenesis and management of acute pulmonary embolism.

Pulmonary embolism can produce severe cardiopulmonary dysfunction characterized by pulmonary artery hypertension, right ventricular failure, and hypoxemia. The search for the source of a pulmonary embolus, by exploration of the veins of the lower limbs and the inferior vena cava should be systematically carried out in all cases of pulmonary embolus which are not immediately life-threatening to the patient. The treatment of deep vein thrombosis associated with pulmonary embolism with thrombolytic agents has been proposed and utilized for approximately 20 years. Although superior results have been claimed with thrombolytic agents, the use of this type of treatment remains limited to massive or sub-massive pulmonary embolism. Fibrinolytic agents with high specificity for fibrin in the thrombi and little systemic activation of the fibrinolytic system have been developed and tested in preliminary clinical trials of patients with acute pulmonary embolism. The largest published experience available has been with recombinant tissue plasminogen activator (rtPA). The acylated streptokinase-plasminogen complex (APSAC) and pro-urokinase also gave promising results. All these agents were accompanied by unexpectedly high incidence of systemic activation of the fibrinolytic system and by hemorrhagic complications with frequencies similar to those that follows the use of first generation products (urokinase and streptokinase). Hence, their superior clinical efficacy must be clearly proven before they are substituted for a more widely available and less expensive drug, such as streptokinase.

Acute Disease↗
PubMed1989

Contribution of peripheral blood pooling to central hemodynamic disturbances during endotoxin insult in intact dogs.

The aim of the present study was to determine possible effects of Escherichia coli endotoxin on peripheral vascular compliance and relate them to concomitant central hemodynamic disturbances. Endotoxin was infused at 0.25 micrograms/kg.min during 2 h in six anesthetized dogs, while six additional animals served as controls. Vascular compliance of the systemic circulation was calculated in intact animals from the changes in CVP after known changes in systemic blood volume. In control dogs, vascular compliance averaged 2.3 ml/mm Hg.kg body weight. During slow endotoxin infusion, cardiovascular effects were measurable only after a certain period of time had elapsed from the start of endotoxin insult and consisted of hypotension associated with systemic vasodilation. Systemic BP decreased gradually from 124 to 68 mm Hg while vascular compliance was finally increased by 100%, when compared to control values. This latter rise was responsible for a reduction in the cardiac preloads. Pulmonary wedge pressure and CVP were decreased from 7.1 to 3.4 and from 4.5 to 2.6 mm Hg, respectively. However, parallel to the decrease in left ventricular preload, endotoxin induced a progressive decrease in left ventricular afterload. Because of the balance in ventricular loading, cardiac output remained almost unchanged. After volume loading (dextran 30 ml/kg), cardiac output was remarkably increased from 3.28 to 6.24 L/min.m2 while peripheral vasodilation was not affected by this maneuver. It is concluded that low dose endotoxin infusion induces in dogs a hemodynamic pattern similar to human sepsis. The left ventricular loading changes are related to an enhanced systemic vascular compliance from 2.3 to 4.5 ml/mm Hg.kg. High flow shock state is encountered provided peripheral blood pooling is compensated by adequate volume replacement.

Animals↗
PubMed1987

Effects of intravascular volume expansion on lung fluid balance in a canine model of septic shock.

We tested the early effects of endotoxin on both the permeability of capillary membranes and microvascular pressure. One group of dogs (n = 8) were fluid loaded (30 ml/kg dextran-40) after having been subjected to a 2-h Escherichia coli endotoxin infusion (0.25 micrograms/kg X min). A second control group of animals (n = 6) was submitted to a similar (25 ml/kg) volume loading over an equivalent 30-min period. We estimated extravascular lung water (EVLW), calculated the effective pulmonary capillary pressure, and determined the alveolar-capillary filtration coefficient (Kf) after volume loading. Only the septic animals consistently showed elevated EVLW values consistent with pulmonary edema. The results showed, however, that the Kf calculated for the dogs that received endotoxin was no different from that of control group (Kf = 0.005 ml/kg X min X mm Hg). Instead, endotoxin constricted the pulmonary veins which led to a considerable rise in microvascular hydrostatic pressure above the level at which the lungs could not resist edema formation. We conclude that acute pulmonary edema that follows endotoxin insult and subsequent therapeutic volume replacement is due to an increased filtration force instead of an alteration in the microvascular permeability.

Animals↗
PubMed1987

A comparison of Escherichia coli endotoxin single bolus injection with low-dose endotoxin infusion on pulmonary and systemic vascular changes.

The purpose of this study was to compare effects of single bolus endotoxin injection with sustained low-dose endotoxin infusion on systemic and pulmonary hemodynamics in anesthetized dogs. When administered as a bolus (.01 mg/kg), endotoxin induced systemic vascular changes whose evolution could be divided into two consecutive phases. In the early phase, marked hepatic venoconstriction caused a rise in portal pressure followed by abrupt decreases in both cardiac output and blood pressure. Mean pulmonary artery pressure remained unchanged. Because of lowered blood flow, both peripheral and pulmonary resistances increased. The rise in the latter was due to a prominent vasoconstriction of pulmonary arteries. Following a partial spontaneous recovery from shock, the late phase was characterized by a low-output state combined with high systemic vascular resistances. In contrast, when endotoxin was given at a slow infusion rate (250 ng/kg/min) over a 2-hour period of time, cardiovascular effects were basically different from the preceding ones, and they were measurable only after a certain period of time had elapsed from the start of endotoxin insult. First, blood pressure decreased gradually, while cardiac output remained almost unchanged. Therefore, peripheral resistance was decreased. Second, in the pulmonary circulation, the site of vasoconstriction was shifted from arteries to veins. We conclude that there is a fundamental difference in the response of the dog's systemic and pulmonary circulation as a function of endotoxin administration as either a bolus or slow infusion. This difference might be due to sudden elevated portal pressure responsible for an abrupt cardiovascular collapse in dogs subjected to bolus injection.

Animals↗
PubMed1987

Pulmonary hydrostatic microvascular pressure changes and lung fluid balance during histamine infusion in intact dogs.

The effects of histamine on systemic and pulmonary hemodynamics of dogs were studied in six intact animals. Histamine infusion resulted in an almost immediate, precipitous fall in blood pressure (BP), pulmonary capillary wedge pressure (PCWP), and right atrial pressure (RA) as well as an increase in heart rate. Partial recovery occurred about 5 minutes after infusion was stopped. Cardiac output did not change significantly. Consequently, the calculated peripheral resistance decreased afterwards. Hepatic portal pressure rose significantly after 2 minutes of histamine infusion with partial recovery in about 5 minutes. Suprahepatic venous pressure did not change significantly. Although pulmonary arterial pressure did not necessarily rise, total pulmonary vascular resistance increased in every dog. If the absolute level in pulmonary arterial resistance remained greater (Ra 105 mm Hg/liter-1 min X kg-1) than the level of venous resistance (Rv 70 mm Hg/liter-1 min X kg-1), the relative increase in venous resistance (100%) was higher than the increase in Ra (35%). On the other hand, effective capillary pulmonary pressure remained unchanged. Central blood volume and extravascular lung water increased upon histamine infusion and returned rapidly to baseline when histamine infusion was stopped. No significant changes occurred in either effective pulmonary compliance and arterial blood gas values. Our data lead us to conclude that histamine's major action occurs in the venous pulmonary segments; pulmonary and splanchnic blood pooling is responsible for a fall in cardiac preload; and an increase in extravascular lung water and central blood volume with unchanged effective pulmonary pressure might be explained by an increase in microvascular surface area.

Animals↗
PubMed1986

Effects of Escherichia coli endotoxin on pulmonary vascular resistance in intact dogs.

The effects of endotoxin on pulmonary hemodynamics were studied in seven intact dogs. The distribution of pulmonary vascular resistance was estimated by the effective pulmonary capillary pressure, which was derived from the pressure transient recorded while the pulmonary artery catheter was rapidly wedged. After the injection of endotoxin, cardiac output and aortic pressure consistently fell. Pulmonary artery occlusion (wedge) pressure also decreased, but not significantly. Although pulmonary artery pressure did not necessarily rise, total pulmonary vascular resistance increased in every dog. The absolute increase in pulmonary artery resistance was greater (142 mm Hg/L X min/kg); than in venous resistance (111 mm Hg/L X min/kg); however, the relative increase in venous resistance was higher (410% for venous resistance vs. 220% for pulmonary artery resistance). As a result of venoconstriction, there was a consistent increase in effective pulmonary capillary pressure (from 2.5 to 6.3 mm Hg). Our data indicate that the pulmonary vascular response to endotoxin injection is characterized by constriction of both pulmonary arteries and pulmonary veins. The capillary wedge pressure did not reflect the pulmonary microvascular pressure, since it varied in the opposite direction to the effective capillary pressure.

Animals↗
PubMed1986

Lack of defective cardiac oxidative metabolism in intact dogs subjected to a prolonged low-dose infusion of Escherichia coli endotoxin.

The aim of the present study was to determine possible direct adverse effects of a 2-hour Escherichia coli endotoxin infusion (50 ng kg-1 min-1) on myocardial oxidative carbohydrate metabolism. The experiments were performed in intact dogs to assay glucose and lactate cardiac uptake and relate them to oxygen consumption (MVO2), CO2 production, and myocardial hemodynamics. Coronary sinus blood flow (CSBF) was measured by thermodilution, and the arteriovenous differences in glucose, lactate, pyruvate, O2, and CO2 were determined by blood samples obtained simultaneously from the carotid artery and sinus coronary. The adequacy of CSBF in meeting cardiac oxygen needs was evaluated by calculating the percentage of anaerobic metabolic rate (% AMR). During endotoxin infusion, CSBF was significantly lowered by 33% while mean aortic blood pressure was decreased by 43%. Cardiac index exhibited a minimal reduction of 14%. Mean arterial blood glucose decreased 30% and arterial lactate increased 100%. Despite the progressively developing hypoglycemia, cardiac glucose uptake increased 140%. Although MVO2 was reduced to 70% of control value, lactate uptake increased 50%. Throughout the experimental period, the % AMR remained negative. Under endotoxin infusion, up to 78% of the cardiac CO2 production was derived from carbohydrate utilization, as compared to 40% prior to endotoxin infusion. Our findings suggest the absence of any toxic action by an endotoxin-sustained infusion on cardiac oxidative metabolism.

Animals↗
PubMed1985

[Hemodynamic and respiratory effects of the perfusion of low-dose endotoxin in intact heparinized dogs].

In the anesthetized dog, a low dose perfusion of endotoxin (50 ng X kg-1 X min-1) produces hemodynamic and metabolic perturbations generally similar to those clinically found in man during the hemodynamic phase of septic shock. These modifications are observed after about 30 minutes following the beginning of the perfusion. They constitute: 1) an arterial vasodilatation responsible for a hypotension without a significant modification of the cardiac output; 2) a drop in the left ventricular filling pressure; 3) a progressive metabolic acidosis; 4) a moderate arterial hypoxia that is independent of an alveolar hypoventilation. To these perturbations is added the contemporary development of a leucopenia associated with a thrombopenia. This mode of endotoxin administration seems to us to constitute a satisfactory experimental model for studying the circulatory injuries due to hyperdynamic septic shock.

Animals↗
PubMed1985

Hemodynamic effects of nifedipine on secondary pulmonary hypertension in man.

We evaluated the hemodynamic effects of the calcium antagonist nifedipine in 13 consecutive patients admitted to the intensive care unit with secondary pulmonary hypertension. Etiology of secondary pulmonary hypertension was: chronic obstructive pulmonary disease (n = 9), pulmonary emboli (n = 2), pulmonary fibrosis (n = 2). We obtained the resting hemodynamic parameters before, and 60, 120, 180 minutes after the sublingual administration of nifedipine 20 mg. All patients had normal pulmonary artery wedge pressure before nifedipine. After 60 minutes, systolic pulmonary artery pressure fell from 72.3 +/- 7 to 57.3 +/- 5.4 mm Hg (p less than 0.005) and mean pulmonary artery pressure from 44.6 +/- 4.0 to 33.6 +/- 3.2 mm Hg (p less than 0.001). Cardiac output rose from 6.36 +/- 0.56 to 7.65 +/- 0.64 l/min (p less than 0.005). The pulmonary vascular resistance fell from 431 +/- 58 to 238 +/- 36 dynes. sec. cm-5 (p less than 0.001). Heart rate, mean systemic arterial pressure, pulmonary artery wedge pressure, total systemic vascular resistance and arterial partial pressure of O2 (PaO2) remained unchanged. In this heterogenous population we were unable to reproduce the results of other authors, showing a correlation between PaO2 and fall of pulmonary vascular resistance. These findings confirm the pulmonary vasodilating effect of nifedipine in patients with secondary pulmonary hypertension.

Blood Pressure↗
PubMed1984

The use of low doses of dopamine in intensive care medicine.

The dopamine alpha- and beta-adrenoceptor dose-response curves are investigated in four patients who are exempt from cardiovascular disease. A dose-related increase in CO, HR and SV is observed with infusion rates of up to 3 micrograms kg-1 min-1. With concentrations greater than 10 micrograms kg-1 min-1, both BP and SVR increase. Low-dose dopamine infusion less than 3 micrograms kg-1 min-1 is investigated in ten other patients. With this infusion rate, a selective renal vasodilation is induced without peripheral or cardiac beta-adrenoceptor activation. Dopamine is responsible for an increase in diuresis FENa, GFR and RBF. These properties are indicated in renal failure, and when haemodynamic support is required in cardiac failure, if an infusion rate of up to 10 micrograms kg-1 min-1 is able to reverse cardiac insufficiency.

Critical Care↗
PubMed1984

[Reciprocal potentiation of the bronchoconstrictor activity of histamine and 5-hydroxytryptamine in the guinea pig].

Bronchoconstriction due to aerosolized histamine (H), 5-hydroxytryptamine (5-HT) and combined administration of both substances has been studied on 53 guinea-pigs. The results are consistant with: a major bronchoconstrictor effect obtained with H than with 5-HT; a potentiation of the individual effects of H and 5-HT in two thirds of the guinea-pigs, by the combined administration of the two drugs simultaneously; a more potent antagonistic effect of Ketanserin against 5-HT than against H; potentiation due to the combined administration of 5-HT and H is suppressed by Ketanserin; neither vagal reflexes nor cholinergic receptors seem to interfere with the bronchospastic response of the guinea-pig to H and 5-HT.

Animals↗
PubMed1984

Pulmonary lymphangiomyomatosis.

Pulmonary lymphangiomyomatosis is a rare disease of smooth muscle proliferation in the walls of lymphatic vessels and in the interstitial areas of the lungs. It only affects women of reproductive age. The majority of patients die from respiratory failure within 10 years. A new observation of pulmonary lymphangiomyomatosis is reported in a woman of 36 years. The disease was discovered at an advanced stage of respiratory failure. Left-sided pleurectomy and treatment with medroxy-progesterone and tamoxifen did not improve the patient's condition.

Adult↗