[Effect of bronchial drainage on the improvement in gas exchange observed in ventral decubitus in ARDS]. / Influence du drainage bronchique dans l'amélioration des échanges gazeux observée en décubitus ventral au cours du SDRA.

OBJECTIVES: A bronchial secretion draining effect is frequently suggested as a mechanism for oxygenation improvement during prone positioning (PP) in patients with acute respiratory distress syndrome (ARDS). Nevertheless, it has never really been evaluated. The aim of this study was to search for an interrelationship between the volume of the bronchial secretion and the improvement of the PaO2/FIO2 ratio during prone positioning, with NO inhalation or not. STUDY DESIGN: Open prospective clinical study. PATIENTS: The study included 15 consecutive patients with severe ARDS (PaO2/FIO2 < 200 after alveolar recruitment, Murray score > 2.5). METHODS: They were returned to the prone position for 4 hours (h0-h4) combined with an inhalation of 5 ppm NO during 1 hour (h2-h3). Tracheal suction were performed hourly between h-2 and h6 and weighed on a precision scale from h-1 to h6. Haemodynamic, blood gas and respiratory compliance were recorded at h0, h2, h3, h4 and h6. RESULTS: No significant haemodynamic changes were observed in the various phases. Compared with the baseline condition at h0, PP and PP + NO respectively improved PaO2/FIO2 by 102 +/- 62% at h2 (P < 0.005) and 156 +/- 79% at h3 (P < 0.005/h0 and < 0.01/h2). 14/15 patients responded to PP and 15/15 to PP + NO (gain in PaO2/FIO2 > 10%). Concerning secretions, we collected 3.0 +/- 7.5 g, 4.4 +/- 6.1 g, 1.7 +/- 1.4 g and 1.7 +/- 1.6 between h-2 and h0, h0 and h2, h2 and h4, h4 and h6. Individual assessments showed no relationship between the PaO2/FIO2 evolution at any time and the quantity of secretions obtained during the first 2 hours in the prone position. Six patients presented secretions of less than 1 g between h0 and h2, and for whom the improvement in oxygenation was higher than average (115 +/- 53% at h2). CONCLUSION: In patients with little or moderate secretions, the improvement observed in oxygenation, with or without NO, does not depend on their volume.

Haemodynamic conditions enhancing gas embolism after venous injury during laparoscopy: a study in pigs.

This study was designed to determine the conditions that promote carbon dioxide embolism after venous injury during laparoscopy in pigs. Injury to an iliac vein was filmed during laparoscopy in the presence of a pneumoperitoneum created at increasing pressures from 0 to 30 mm Hg in 5-mm Hg increments. At intraperitoneal pressures less than 20 mm Hg, there was a parallel increase in femoral venous pressures, resulting in haemorrhage, with persistent blood flow to the inferior vena cava. At intraperitoneal pressures of 20-30 mm Hg, there was collapse of the femoral vein, occurring earlier in the presence of hypovolaemia. Between these two states (haemorrhage and collapse), there was a point of equilibrium which allowed retrograde venous penetration of carbon dioxide bubbles. During release of the pneumoperitoneum, these bubbles were exteriorized through the area of the injury, but some passed into the inferior vena cava where their presence was detected by an oesophageal Doppler probe.

Serum erythropoietin and reticulocyte counts in inflammatory process.

The role of erythropoietin in the pathogenesis of anaemia associated with inflammatory disorders is unclear. We studied serum erythropoietin levels in patients with inflammatory process of varying aetiologies. Serum erythropoietin levels and reticulocyte counts were prospectively measured in 40 patients with inflammatory syndromes and compared with values obtained in 20 patients with myelodysplastic syndromes. Significant inverse correlation between erythropoietin levels and haemoglobin concentration were noted in the 2 groups. The slope of the regression line for patients with inflammatory disorders was lower as compared with that for the myelodysplastic syndromes. In all cases, when the erythropoietin response in relation to degree of anaemia is compared with that which occurs in patients with myelodysplastic syndromes, the inadequate erythropoietin response in patients with chronic inflammatory process becomes evident. In patients with inflammatory process, a relationship between erythropoietin levels and reticulocyte counts were only noted in patients with mildly anaemia (haemoglobin concentration higher than 10.5 g/dl). This study suggests blunted erythropoietin production and impaired marrow response to this hormone in the anaemia which occurs in inflammatory syndromes and supports the hypothesis that these disorders may contribute to the development of the anaemia associated with inflammatory disorders.