[Clinical value of bronchoalveolar lavage]. / Uitlité clinique du lavage bronchoalvéolaire.

Bronchoalveolar lavage (BAL) is a minimally invasive procedure used to characterize the status of the alveolar space. Standardization of the procedure and the analysis of samples taken is essential for their proper interpretation. In nonresolving or ventilator-associated pneumonia, BAL contributes to the detection of resistant pathogens and noninfectious etiologies. In immunocompromised hosts with radiological infiltrates, BAL should be performed early during work-up since outcome is significantly modified in this population group. In cases of interstitial lung disease, BAL can exclude infectious or neoplastic causes. Associated with a clinical and radiological evaluation, it provides valuables additional diagnostic information.

[Non-invasive central blood pressure measurement: how and why?]. / Mesure non-invasive de la pression artérielle centrale: comment et pourquoi?

Until today, the usual way to measure arterial blood pressure has been cuff sphygmomanometry, at the level of the brachial artery. Yet, for some years, a non invasive tool has been available, that enables an estimation of the aortic pressure. This is done by using an aplanation tonometry technique to record the pulse wave within the radial artery, with subsequent convertion to a central pressure wave by means of a mathematical method (transfer function). This measurement informs us about the pressure near the target organs: this pressure is influenced by the reflected waves, which are responsible for an augmentation of systolic blood pressures when arterial compliance is abnormally low. Recent clinical trials have shown that for the same value of peripheral blood pressure, different antihypertensive treatments may not impact identically on central blood pressure.

Analysis of factors that contribute to treatment failure in patients with community-acquired pneumonia.

To determine the causes of treatment failure and to evaluate the prognostic factors in patients hospitalized for community-acquired pneumonia, a prospective, observational study of 228 adult patients hospitalized for a community-acquired pneumonia in the University Hospital of Geneva and the La Chaux-de-Fonds Community Hospital, Switzerland, was conducted. The percentage of patients who failed to improve (as defined by guidelines of the Infectious Disease Society of America) and the causes of treatment failure were assessed, and patients who failed to improve under antimicrobial therapy were compared with those who did improve. In the 54 (24%) patients who failed to improve, a mean increase in length of hospitalization of 4 days was observed. Most causes of treatment failure could be attributed to host factors (61%) rather than to the pathogen (16%) or to an inappropriate antibiotic regimen (3%). After adjusting for potentially confounding variables, concomitant neoplasia (OR 3.25; 95%CI 1.11-9.56), neurological disease (OR 2.34; 95%CI 1.07-5.13), and aspiration pneumonia (OR 2.97; 95%CI 29-6.86]) were associated with failure to improve, whereas monocytosis improved prognosis (OR 0.40; 95%CI 0.20-0.80). Almost one out of four patients hospitalized for community-acquired pneumonia failed to respond to empirical antibiotic treatment. Aspiration pneumonia, concomitant neoplasia, and neurological disease were factors positively associated with failure to improve, whereas monocytosis was linked to a better prognosis.

Effects of water temperature on performance: a practical evaluation of a neutral buoyancy facility.

Manual and cognitive performance of two female and four male divers was evaluated in "cold" and "warm" water in a Neutral Buoyancy Facility (NBF). A test battery of six manual and cognitive tests was applied in a fixed sequence in three separate, 3-h dives: Dive 1) Water temp.: 18-19 degrees C, wet suit 3-5 mm thick; Dive 2) Water temp.: 32-33 degrees C bathing suit and T-shirt; and Dive 3) Water temp.: 18-19 degrees C, tailor made wet suit 6.5 mm thick. No significant differences in performance between the three conditions were recorded. Mean rectal temperatures decreased by 1 degree C in all dive conditions, except in females in Dive 2. Ventilation was significantly higher in Dive 1 than in Dives 2 and 3. Thermal discomfort was reported only after 2 h in Dive 1. We suggest that support divers may work safely, comfortably and effectively for at least 2 h in water of 18-19 degrees C, if dressed in thermal protective wet suits.

Pulmonary mechanical function and diffusion capacity after deep saturation dives.

To assess the effects of deep saturation dives on pulmonary function, static and dynamic lung volumes, transfer factor for carbon monoxide (T1CO), delta-N2, and closing volume (CV) were measured before and after eight saturation dives to pressures of 3.1-4.6 MPa. The atmospheres were helium-oxygen mixtures with partial pressures of oxygen of 40-60 kPa. The durations of the dives were 14-30 days. Mean rate of decompression was 10.5-13.5 kPa/hour. A total of 43 divers were examined, six of whom took part in two dives, the others in one only. Dynamic lung volumes did not change significantly but total lung capacity (TLC) increased significantly by 4.3% and residual volume (RV) by 14.8% (p less than 0.05). CV was increased by 16.7% (p less than 0.01). The T1CO was reduced from 13.0 +/- 1.6 to 11.8 +/- 1.7 mmol/min/kPa (p less than 0.01) when corrected to a haemoglobin concentration of 146 g/l. Effective alveolar volume was unchanged. The increase in TLC and decrease in T1CO were correlated (r = -0.574, p less than 0.02). A control examination of 38 of the divers four to six weeks after the dives showed a partial normalisation of the changes. The increase in TLC, RV, and CV, and the decrease in T1CO, could be explained by a loss of pulmonary elastic tissue caused by inflammatory reactions induced by oxygen toxicity or venous gas emboli.

Respiratory function in the upright, working diver at 6.8 ATA (190 fsw).

The influence of static lung loading on a number of respiratory parameters was investigated in subjects performing graded leg exercise in an upright posture while submerged and breathing air at ambient pressures up to 6.76 ATA. In comparison with a previous investigation of the prone posture, a lesser tendency to dyspnea was observed. Neutral and moderately positive static lung loads were associated with less dyspnea than were negative loads. Several indices of respiratory function remained relatively normal during exercise and exposure to varying static lung loads. However, there was a tendency for hypoventilation and CO2 accumulation during heavy exercise at 190 fsw; this was not strictly correlated with dyspnea or static lung load. We conclude that, if a full face mask is used, breathing gear for divers should provide a static lung load of approximately 0 to +10 cmH2O regardless of the diver's orientation in the water. When possible, divers should assume an upright posture while engaged in strenuous work.

Weight loss and catabolic adaptations to starvation in grey seal pups.

Five grey seal pups lost from 18 to 32% of their initial body weight during a 21 day starvation period. Blubber fat mass density was 0.93 +/- 0.03 g/cm3. A considerable loss of blubber fat was recorded, but analysis of the weight loss and body size data indicated that blubber fat was retained for thermoregulatory reasons, particularly in the lean, smaller seals. It is possible that phocid seals during periods of negative energy balance have a higher rate of protein catabolism than normal for terrestrial mammals.

Influence of exercise on maximal voluntary ventilation and forced expiratory flow at depth.

Four to six subjects performed maximal voluntary ventilation (MVV) and forced expirations during rest, exercise (50, 125, and 200 W), and inhalation of air and CO2 and air at rest while submerged at pressures of 1.45, 2.82, 4.64, and 6.76 atm. Maximal expiratory flow (at 40% of vital capacity) and MVV at rest decreased as exponential functions of gas density, but the decrease was less than in some earlier studies. Independent of pressure, MVV increased by about 10%-17% at the heavier work loads and expiratory flow increased by 27%-48%; the increase in expiratory flow disappeared within 2 min after exercise. Exercise increased end-tidal CO2 tension by up to 9 mmHg. Carbon dioxide inhalation increasing the end-tidal level by up to about 25 mmHg during rest had no effect on MVV and a slight to moderate effect on flow, increasing it by a maximum of 21% at 4.64 atm. The enhancing effect of exercise on MVV and expiratory flow at depth apparently was mainly due to modified autonomic nervous activity reducing pulmonary flow resistance, CO2 accumulation playing an uncertain role, and passive distension of airways playing no role.

The effect of hypercapnia on respiratory characteristics and diving behaviour of freely diving seals.

Three trained young seals, one harp seal, Pagophilus groenlandicus, and two hooded seals, Cystophora cristata, have been used to study the effect of hypercapnia on respiratory characteristics and diving behaviour. The seals were allowed free movements within a circular pool, while diving and respiratory behaviour were recorded. During the experiments the alveolar CO2 tension was continually recorded. There was a significant decrease in duration of dives with increasing Paco2 for all animals. Ve increased significantly with increasing Paco2. This increase was caused by more frequent surfacing rather than by a higher respiratory frequency during the breathing periods. Tidal volume increased from 3 to 43% when inspired CO2 was increased from 0.03 to 9 vol%. The seals were all found to be less sensitive to CO2 than man. A decreased sensitivity to CO2 with age is suggested from the results.