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Biomedical subjects

G Manier

Publications and source records attributed to G Manier.

36 records · Page 2Linked to original sources
PubMed1989

Hemodynamic disturbances and VA/Q matching in hypoxemic cirrhotic patients.

Arterial oxygen desaturation is commonly found in patients with cirrhosis of the liver, but severe hypoxemia is unusual. To investigate the mechanism of the impairment in gas exchange, six severely hypoxemic (mean PaO2, 55.9 +/- 5.9 mm Hg) cirrhotic patients (five confirmed by biopsy), without pulmonary or cardiovascular disease and in the absence of acute hepatic disease, were submitted to right heart catheterization. Inequalities of VA/Q were estimated in the respiratory steady state using the multiple inert gas technique. The mean pulmonary arterial pressure was low (7.2 +/- 2.3 mm Hg) and the cardiac output high (Q = 11.0 +/- 2.06 L/min), indicating a low PVR. The VA/Q mismatching of the ventilated and perfused units ranged from mild to moderate, but a large percentage of Q flowed through unventilated areas. Furthermore, there was a significant difference between predicted and measured PaO2 (9.27 +/- 5.9 mm Hg; p less than 0.01), which was attributed to either an unmeasured postpulmonary shunt (between portal and pulmonary vein) or a diffusion defect. The impairment in gas exchange in these patients is thus due primarily to an intrapulmonary, and possibly extrapulmonary, shunt. This was thought to be due mainly to an impaired regulatory mechanism of the microcirculation by the hepatic dysfunction.

Adult↗
PubMed1988

Pulmonary gas exchange in Andean natives with excessive polycythemia--effect of hemodilution.

Pulmonary gas exchange in Andean natives (n = 8) with excessive high-altitude (3,600-4,200 m) polycythemia (hematocrit 65.1 +/- 6.6%) and hypoxemia (arterial PO2 45.6 +/- 5.6 Torr) in the absence of pulmonary or cardiovascular disease was investigated both before and after isovolemic hemodilution by use of the inert gas elimination technique. The investigations were carried out in La Paz, Bolivia (3,650 m, 500 mmHg barometric pressure). Before hemodilution, a low ventilation-perfusion (VA/Q) mode (VA/Q less than 0.1) without true shunt accounted for 11.6 +/- 5.5% of the total blood flow and was mainly responsible for the hypoxemia. The hypoventilation with a low mixed venous PO2 value may have contributed to the observed hypoxemia in the absence of an impairment in alveolar capillary diffusion. After hemodilution, cardiac output and ventilation increased from 5.5 +/- 1.2 to 6.9 +/- 1.2 l/min and from 8.5 +/- 1.4 to 9.6 +/- 1.3 l/min, respectively, although arterial and venous PO2 remained constant. VA/Q mismatching fell slightly but significantly. The hypoxemia observed in subjects suffering from high-altitude excessive polycythemia was attributed to an increased in blood flow perfusing poorly ventilated areas, but without true intra- or extrapulmonary shunt. Hypoventilation as well as a low mixed venous PO2 value may also have contributed to the observed hypoxemia.

Adult↗
PubMed1986

Heat and water respiratory exchanges: comparison between mouth and nose breathing in humans.

The temperatures (TI, TE) of inspired and expired gas and the mass of expired water (MEH2O) have been measured in four subjects at rest during mouth and nose breathing of dry air at room temperature. TI and TE were measured by copper-constantan thermocouples, MEH2O by freezing and ventilatory parameters by total body plethysmography. During mouth breathing, temperatures are significantly higher (TI = 28.1 degrees C, TE = 31.5 degrees C) and the amount of expired water larger (MEH2O = 27.8 mg dm-3 BTPS) than during nose breathing (TI = 24.8 degrees C; TE = 29.6 degrees C; MEH2O = 26.6 mg dm-3 BTPS). From these experimental data the appropriate computations show clearly that in humans, while either nose or mouth breathing, the expired air is not water saturated; the latent heat exchanges represent the larger part of the respiratory heat exchanges; the counter current expiratory heat recovery is imperfect; in terms of heat and water respiratory exchanges, no large difference exists between the oral and nasal routes. This last point is confirmed by the calculation of a difference less than 10% in the total respiratory heat losses between mouth and nose breathing.

Body Temperature Regulation↗
PubMed1986

Improvement in ventilation-perfusion relationships by almitrine in patients with chronic obstructive pulmonary disease during mechanical ventilation.

Although the respiratory stimulant effects of almitrine bismesylate (AB) via an action on the peripheral chemoreceptors have been demonstrated, the mechanism of its intrapulmonary action has not yet been elucidated. In order to abolish the stimulation of ventilation, observed in studies on spontaneously breathing patients, an investigation of patients suffering from severe COPD under constant mechanical ventilation, with FIO2 = 0.21, during the weaning period was carried out. Eighteen patients were randomly divided into 2 groups (9 receiving 1.5 mg/kg AB and 9 receiving placebo). The ventilatory and hemodynamic variables, blood and alveolar gases, and the VA/Q ratio distributions using the multiple inert gas technique were collected before treatment with drug or placebo, as well as 90 and 180 min afterwards. The PaO2 was found to be raised 90 min after AB administration (+57 +/- 3.9 mm Hg, p less than 0.01) and remained above the baseline value at 180 min (+5.4 +/- 4.6 mm Hg, p less than 0.01). Compared with those in the placebo group, these increases were significant (p less than 0.01). A slight decrease in PaCO2 but similar in the 2 groups was observed despite constant ventilation. The hemodynamic data were the same for the 2 groups. The changes in overall criteria of the distributions (mean VA/Q and SD) were small. The main finding was a decrease in the percentage of the perfusion flowing through the true shunt and the underventilated areas after AB treatment. In the control group, the blood flow percentage in the true shunt and low VA/Q units was either stable or increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Almitrine↗
PubMed1985

Series dead space for inert gases in healthy subjects.

In ten normal subjects, series dead space was determined for six intravenously infused inert gases (SF6, ethane, cyclopropane, fluothane, ether, acetone) from their expired and alveolar concentrations. The method for sampling alveolar gas was based on the criterion of identity of mean alveolar and expired gas exchange ratios. Inert gases were analysed chromatographically. Acetone, the most soluble gas, yielded the lowest dead space, the difference to the other gases being about 4.5%. This is probably due to the non-infinite value of the series dead space ventilation-perfusion ratio (VA/Q) which was estimated at about 2,000. The diffusivity, inversely related to the molecular weight, also played a role, the heaviest gas (fluothane) having a greater dead space than the lightest (ethane). The underestimation of the dead space from acetone is expected to be greater in subjects with low tidal volume and high bronchial blood flow, i. e. in some patients with respiratory disease.

Humans↗
PubMed1985

Acute inflammatory demyelinating polyneuropathy in a diabetic patient: predominance of vesicular disruption in myelin sheaths.

A diabetic woman underwent an incision of the right big toe for an abscess and developed a typical Guillain-Barré syndrome 48 h later. A biopsy of a peripheral nerve, performed 10 days later, showed modifications usually seen in diabetic patients, as well as the characteristic ultrastructural modifications of the Guillain-Barré syndrome (GBS). Moreover, 22% of myelinated fibers exhibited vesicular disruption of the myelin sheaths. This lesion is rarely encountered on the biopsies of peripheral nerve in GBS and concerns only a few myelinated fibers. Such a prominence of myelinic vesicular disruption and its occurrence in a diabetic patient are discussed.

Acute Disease↗
PubMed1985

Determinants of hypoxemia during the acute phase of pulmonary embolism in humans.

The determinants of hypoxemia were studied in 10 patients with acute pulmonary embolism demonstrated by pulmonary angiography. Two patients were mechanically ventilated, and in the 8 who breathed room air spontaneously, the mean arterial PO2 was 61.5 mmHg. Measurements of the distributions of ventilation (VA) and perfusion (Q) against VA/Q ratios by the multiple inert gas infusion technique demonstrated an increase in VA/Q inequality. The major part of pulmonary blood flow was distributed in a mode near to, or slightly above, a VA/Q ratio of 1. The cumulative fraction of blood in true shunt and low VA/Q mode (VA/Q less than 0.01) was 9.1%. For a small part of the AaDO2 (13%), an oxygen diffusional component was found. The remaining hypoxemia was due to the fall in the mixed venous PO2 (PVO2), irrespective of its cause: low cardiac output, low hemoglobin concentration, high oxygen consumption, low P50. The fall in PVO2 led to a fall in end-capillary blood PO2 in both shunt or ventilated and perfused units. We conclude that the major determinant of hypoxemia in these patients suffering from acute pulmonary embolism is the fall in PVO2. This is enhanced by a moderate increase in the fraction of blood flowing through low VA/Q units. Diffusion impairment plays only a minor role.

Acute Disease↗
PubMed1985

Gas exchange alterations in patients with chronic obstructive lung disease.

In a series of 23 patients with COPD, Wagner et al showed three distinct patterns of VA/Q distributions and a correlation between Burrows' clinical classification and the observed distribution patterns. Using the inert gas method, we studied 51 patients suffering from severe but stable COPD (FEV1 = 0.84 +/- 0.38 L; PaO2 = 58.5 +/- 10.5 mm Hg; PaCo2 = 48 +/- 6 mmHg; Ppa = 22 +/- 8 mmHg) breathing room air in a steady state. The H pattern (high mode of VA in high VA/Q) was found in 24 cases. There was an L pattern (Q mode in low VA/Q units) in nine cases and an HL (high-low) pattern in 16 cases (two patients were assigned another group). The analysis of the distribution data confirmed that VA/Q heterogeneity was the main factor underlying gas exchange disturbances in COPD. The PaO2 of the H subjects was higher than that of both HL (p less than 0.02) and L subjects. The true shunt value in the L group was significantly lower than in the H and HL groups. However, the relationship between clinical or functional aspects and distribution was not direct. The fraction of patients of H, HL, or (H + HL) types was nearly identical in the three clinical groups. The H pattern was found to be predominant in cases of COPD.

Aged↗
PubMed1985

[The inert gas method in respiratory physiopathology].

The main results obtained, in healthy or unhealthy man, with the inert gas method are gathered together. The major factor at the source of hypoxemia is the uneven distribution of VA/Q ratios. The fall in the partial pressure of oxygen in mixed venous blood amplifies this effect. Only hypoxemia, during muscular exercise, in patients with interstitial lung diseases could be explained, in part, by a decrease in membrane diffusion and a reduction in the transit time of blood in pulmonary capillaries. The differences between the methods used to analyse pulmonary gas exchange are discussed.

Adult↗
PubMed1985

[Outcome of patients with chronic respiratory insufficiency treated at home with tracheotomy and assisted ventilation].

60 patients were studied with severe chronic respiratory failure (IRC) and a permanent tracheostomy treated with domiciliary ventilation (VADT). The study commenced from the time of the tracheostomy and included length of survival (by the actuarial method) quality of life, subjectively and objectively (progress of blood gases in a stable clinical state and cumulative length of periods in hospital). Factors influencing the decision for tracheostomy and VADT were examined. Restrictive cases benefitted from the technique as much from the improved quality of life as from the duration of survival (77% at 5 years). Patients with an obstructive or mixed pattern had a 5 years survival of 73% after the first episode of acute or chronic respiratory failure which was 73% better than comparable patients given neither a tracheostomy nor oxygen therapy. The five years survival of 42% on VADT in our series compares favourably with the main series published. In our opinion the improved survival in these patients (which tends to rejoin that of the general population) and the improved quality of life justifies the use of this treatment in severe obstructive IRC, despite a greater demand and cost of this treatment than those with a restrictive defect.

Actuarial Analysis↗
PubMed1984

[Influence of almitrine dimesylate on gas exchange. Preliminary results in patients with chronic obstructive bronchopneumopathies under artificial ventilation].

From a study conducted in 1981 in patients with chronic obstructive pulmonary disease breathing spontaneously, it was concluded that almitrine ensured a more even distribution of ventilation-perfusion ratios in the lung. Another study has recently been undertaken to suppress the effects of stimulated ventilation observed and to measure more accurately the pulmonary vascular effect of this new drug. This was a randomized double-blind drug versus placebo trial using the same doses of almitrine (1.5 mg/kg orally) in patients of the same type under stable artificial respiration controlled by repeated measurements of ventilation during the weaning period at the end of an episode of acute respiratory failure. The preliminary results obtained in one-half of the patients (4 under almitrine, 4 under placebo) are reported. There was little difference in haemodynamic values between the two groups. Improvement in PaO2 was maximum 90 min after almitrine was administered and varied from 0.7 to 1.4 kPa; there was no modification in the control group. In the absence of any change in ventilation and respiratory rate, perfusion was reduced in lung areas with low ventilation-perfusion ratio. These partial results seem to confirm that almitrine exerts a moderate, though real, effect on pulmonary vessels.

Almitrine↗
PubMed1983

[Treatment of 3 cases of status asthmaticus with halothane].

Three serious cases of status asthmaticus with severe hypercapnic acidosis unresponsive to adequate conventional therapy were treated by halothane. The efficiency of this treatment was assessed by the clinical state of the patient, the blood gases and the changes in peak airway pressure. Two patients improved dramatically in less than 24 h. No signs of cardiac toxicity of this drug were noted in spite of acid-base disturbances. These three cases showed the beneficial effect of halothane's-beta 2 stimulation in the treatment of status asthmaticus.

Acute Disease↗
PubMedDate not supplied

Effect of 26% oxygen breathing on ventilation and perfusion distribution in patients with cold.

Fourteen patients suffering from severe but stable chronic airway obstruction were studied while breathing room air and mildly hyperoxic mixture (26%). The data were collected at the end of each 30 min randomized breathing period. The multiple inert gas elimination technique was used to detect alterations in ventilation-perfusion (VA/Q) mismatching. Ventilatory, arterial and mixed venous blood gases, and hemodynamic measurements were made simultaneously. To show a possible effect of O2 on hypoxic pulmonary vasoconstriction (HPV), the fractional part of cardiac output perfusing low VA/Q areas was separated using as upper limit of VA/Q the compartments with PAO2 70, 60 and 50 mmHg while breathing oxygen, compared to the percentage of blood flow in the same areas limited by the same VA/Q unit in air breathing conditions. Only a few changes due to O2 are statistically significant: 1) a rise in PaO2 (+20.2 +/- 8.3 mmHg) and PvO2 (+4.2 +/- 2.18 mmHg) without any change in ventilation, respiratory frequency, pH, PaCO2, haemodynamics and overall criterion of distribution; 2) a moderate increase in inert gas dead space; 3) an increase in the percentage of blood flow under the limit when chosen at 50 mmHg (+3 +/- 2.8%). This change could be related to an inhibition of HPV response while breathing O2 in compartments previously placed above the limit in air. Consequently, their VA/Q decrease and their perfusions are summed with those under the limit in O2. These data suggest that mild hyperoxia has a slight but real deleterious effect on pulmonary gas exchange.

Aged↗
PubMedDate not supplied

[Inert gas study of heliox gas exchange in patients with COPD].

Ventilation and perfusion distributions were measured in the patients with COPD breathing room air and normoxic helium-oxygen mixture (heliox) successively, using the multiple inert gas method. The D (A-a) O2 were calculated from ideal alveolar gas (Ai) and with West's gas mean model (A). Measured PaO2 and predicted PaO2 were compared during room air and heliox breathing. There were no change in overall distributions and in D (Ai-a) while D (A-a) O2 increase significantly during heliox breathing and the predicted PaO2 were significantly higher than the measured PaO2. Heliox breathing does not seem to change parallel heterogeneity in COPD. These results suggest an impairment of series heterogeneity and O2 diffusion during heliox breathing.

Helium↗
PubMedDate not supplied

[Toxoplasma encephalitis in acquired immunodeficiency syndrome].

Several outbreaks of fatal opportunistic infections and tumors have recently been reported among homosexual men in the United States. Almost all patients had evidence of cellular immunodeficiency. We have studied a French homosexual man with fatal central nervous system toxoplasmosis. Morphological features (light and electron microscopy) of toxoplasma encephalitis are described.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[Pulmonary edema in pulmonary embolism].

We report a case of severe pulmonary embolism in a 37 years old man admitted to the intensive care unit for severe acute respiratory failure. The presenting signs and symptoms were typical for severe pulmonary oedema. Chest radiograph shortly after admission showed local alveolar shadows. In the absence of sepsis, haemodynamic evidence of left ventricular failure on catheterization of the right heart and because of the history of the recent illness, a tentative diagnosis of pulmonary embolism was made. The diagnosis was confirmed by selective pulmonary angiography. The latter demonstrated that pulmonary oedema had been localized only in areas with patent pulmonary arteries and, in addition, confirmed that left ventricular function was normal. Such a pattern of local pulmonary oedema is uncommon in patients and is reminiscent of that observed in animal experiments with severe pulmonary arterial obstruction and overperfusion of unblocked territories. Possible mechanisms of overperfusion oedema are discussed and the hypothesis that humoral factors may increase the permeability of pulmonary microvasculature in cases of severe pulmonary embolism is put forward.

Adult↗
PubMedDate not supplied

[Effects of oral almitrine on the distribution of VA/Q ratio in chronic obstructive lung diseases (author's transl)].

A double blind study of effects of a low dose of almitrine has been performed in patients with severe chronic obstructive lung diseases. Besides hemodynamic and ventilation data, ventilation-perfusion ratio distribution was measured by the inert gas method in order to try to explain the improvement in blood gases caused by this drug. At the dose of 1.5 mg/kg almitrine produces : 1) an increase in ventilation and PaO2, 2) no change in pulmonary vascular resistances compared to a rise on placebo, 3) a drop of 4% in the percentage of cardiac output perfusing low VA/Q lung units with a concomitant increase in lung units with VA/Q ratio between 0.1 and 10, and 4) no significant change in the distribution of ventilation. The change in the distribution of blood flow is one of the causes of the rise in PaO2, but its mechanism is at yet not clear. The present results suggest arterial vasoconstriction in units with very low VA/Q accompanied by diversion of blood flow towards lung units with higher VA/Q ratio.

Aged↗