[Interest of the brain natriuretic peptide as a marker of acute cor pulmonale in acute respiratory distress syndrome]. / Analyse du peptide natriurétique de type B comme marqueur du coeur pulmonaire aigu dans le syndrome de détresse respiratoire aiguë.

OBJECTIVE: The aim of this study was to evaluate the accuracy of the BNP as a marker of acute cor pulmonale in patients with ARDS. STUDY DESIGN: Prospective clinical trial. PATIENTS AND METHODS: At day 2 or 3 after the onset of the ARDS, an echocardiography was performed. Patients with left ventricular dysfunction were excluded. Right ventricular area (RVA) and RVA/LVA ratio were measured. ACP was defined as RVA/LVA > 0.6 associated with septal dyskinesia. Simultaneously, 5 ml of blood was collected for BNP measurement. RESULTS: 26 patients were studied. BNP levels were higher in 10 patients with ACP: 585.5 [189-4830] vs 145.5 [36.5-346] pg/ml (P=0.01) but in those with creatinine clearance < 90 ml/min: 602 [331-3530] vs 125 [39-189] pg/ml (P=0.007). BNP was correlated with RVA (r=0.5; p=0.01), RVA/LVA ratio (r=0.61; p=0.001), sPAP (r=0.58; p=0.002) and with age, cardiac index and creatinine clearance (r=0.61; p=0.001). In multivariate analysis, BNP was only correlated with creatinine clearance (p=0.03), and RVA (p=0.06). CONCLUSION: In ARDS patients without left ventricular dysfunction, BNP level is more elevated in patients with acute cor pulmonale than patients without cor pulmonale.

Exhaled carbon monoxide in mechanically ventilated critically ill patients: influence of inspired oxygen fraction.

OBJECTIVE: To assess the feasibility of exhaled carbon monoxide (CO) measurements in mechanically ventilated critically ill adult patients and to determine the influence of inspired oxygen fraction on this measurement. DESIGN: Prospective physiologic study. SETTING: Medical ICU in a community hospital. PATIENTS: The study was performed on nine mechanically ventilated patients with varying diagnoses. MEASUREMENTS AND RESULTS: Carbon monoxide concentration was determined with an infrared CO analyzer on exhaled breath collected at the outlet of the ventilator. We assessed the stability of exhaled carbon monoxide concentration over a 4-hour period and determined its course during a 7-hour period after inspired oxygen fraction had been abruptly increased from baseline to 1. Carbon monoxide was detected in exhaled breath in each patient at a higher concentration than in inspired gas (0.64 +/- 0.1 ppm vs 0.25 ppm, approximately). Exhaled carbon monoxide did not vary during a 4-hour period in five hemodynamically stable patients. When inspired oxygen fraction was increased from baseline (0.52 +/- 0.04) to 1, exhaled carbon monoxide concentration increased abruptly from baseline (0.63 +/- 0.13 ppm) to a peak value of 1.54 +/- 0.16 ppm within 15 min and returned slowly to baseline values within 7 h. CONCLUSION: CO was easily detected in the exhaled breath of mechanically ventilated patients and CO lung excretion was markedly but transiently dependent on inspired oxygen fraction. Other studies are warranted in order to determine the different factors that might influence CO lung excretion in critically ill patients.

Antibiotic levels in bronchial tree and in serum during selective digestive decontamination.

Selective digestive decontamination has been found to prevent pulmonary infections in mechanically ventilated patients. The aims of this study were: 1) to determine whether detectable levels of antibiotics could be found in bronchial tree secretions of patients receiving SDD, and 2) to evaluate antibiotic serum levels. In 15 patients receiving mechanical ventilation and SDD for 10 days or more, tobramycin and amphotericin B levels were determined every 3 days in the following specimens: tracheal aspirates, distal bronchial secretions and blood samples. 82% of tracheal aspirates contained detectable (greater than 0.18 mg/l), tobramycin concentrations; the levels varied widely between patients and large day-to-day variations were observed. Every patient had at least 1 tracheal aspirate with tobramycin level higher than 0.5 mg/l during his course. 40% of distal specimens contained detectable tobramycin levels (10 patients). Serum determinations showed detectable concentration of tobramycin in 50% of the specimens (9 patients). Two patients with renal failure had serum tobramycin levels higher than 2 mg/l. In 13 tracheal aspirates cultures were positive and 15 species were isolated; 13 had a MIC higher than the corresponding tobramycin level in tracheal secretions. We conclude that substantial levels of antibiotics can be found frequently in respiratory tract specimens of patients receiving SDD. Therefore, the usual microbiological criteria used to assess respiratory tract infection may be unreliable in this setting and other criteria may be required. Follow-up of antibiotic serum levels is required, especially in patients with renal failure.

[Humidification and aspiration of the respiratory tract in patients with mechanical ventilation]. / Humidification et aspiration des voies aériennes du malade sous ventilation mécanique.

Mechanical ventilation through endotracheal prosthesis, suppresses the nose functions and stops elimination of secretions. It is mandatory to heat artificially, humidify insufflated gas and to suction tracheobronchial secretions. Heating humidifiers are very efficient for the first purpose but heat and moisture exchangers, a little less efficient, seem to be a good alternative as they are easiest to use and offer a good bacterial protection. Tracheobronchial suctioning has to be carried out at least each four hours and at the best as soon as adventitious sound are heard in the chest. Suction catheters have to be atraumatic; vacuum has to be between -200 to -400 cm H2O; catheter have not to be pushed further than the carina; suction hypoxemia can be reduced by shortening suction maneuver, by using suction catheter with little diameter, by conducting the suction on mechanical ventilation.