Metabolomics is a comprehensive method for metabolite assessment that involves measuring the overall metabolic signature of biological samples. We used this approach to investigate biochemical changes due to acute and chronic physical exercise. Twenty-two women using identical oral contraceptives were segregated into an untrained (n = 10) or trained (n = 12) group depending on their physical training background. The subjects performed two exercises in a randomized order: a prolonged exercise test (75% of their VO(2 max) until exhaustion) and a short-term, intensive exercise test (short-term, intensive exercise anaerobic test). Urine specimens were collected before and 30 min after each test. The samples were analyzed by (1)H NMR spectroscopy, and multivariate statistical techniques were utilized to process the data. Distinguishing characteristics were observed only in the urine profiles of specimens collected before vs. 30 min after the short-term, intensive exercise test. The metabolites responsible for such changes were creatinine, lactate, pyruvate, alanine, beta-hydroxybutyrate, acetate, and hypoxanthine. In both groups, the excretion of lactate, pyruvate, alanine, beta-hydroxybutyrate, and hypoxanthine increased similarly after the completion of the short-term, intensive exercise test (p < 0.03). However, acetate excretion increased to a lesser extent in trained than in untrained subjects (p < 0.05). In conclusion, metabolomics is a promising tool in order to gain insight into physiological status and to clarify the changes induced by short-term, intense physical exercise.

Sleep is markedly altered in intensive care unit (ICU) patients and may alter respiratory performance. Our objective was to assess the impact of sleep alterations on weaning duration.We conducted a prospective physiological study at a French teaching hospital. ICU patients intubated for at least 24 h and difficult to wean were included. Complete polysomnography (PSG) was performed after the first spontaneous breathing trial failure. Presence of atypical sleep, duration of sleep stages, particularly rapid eye movement (REM) sleep, and electroencephalogram (EEG) reactivity at eyes opening were assessed by a neurologist.20 out of 45 patients studied (44%) had atypical sleep that could not be classified according to the standard criteria. Duration of weaning between PSG and extubation was significantly longer in patients with atypical sleep (median (interquartile range) 5 (2-8) 2 (1-2) days; p=0.001) and in those with no REM sleep compared with the others. Using multivariate logistic regression analysis, atypical sleep remained independently associated with prolonged weaning (>48 h after PSG). Altered EEG reactivity at eyes opening was a good predictor of atypical sleep.Our results suggest for the first time that brain dysfunction may have an influence on the ability to breathe spontaneously.

It has long been claimed that the active expiratory glottic closure observed in newborns, especially during hyaline membrane disease, is related to hypoxia. However, we recently showed that hypoxia does not lead to active expiratory glottic closure in nonsedated lambs. In this study, we test the hypothesis that glottic closure is related to an excess of lung water present at birth. We studied 17 nonsedated lambs after inducing a permeability pulmonary edema via intravenous of either oleic acid (8 lambs) or halothane (9 lambs). We recorded airflow via a facial mask and pneumotachograph, as well as the electromyographic activity (EMG) of the thyroarytenoid muscle (TA), a glottic adductor. Blood gases were measured in 8 lambs via a brachial artery catheter. We identified laryngeal expiratory airflow braking on the breath-by-breath computed flow-volume loop and TA expiratory EMG as evidence of active expiratory glottic adduction. After the injection of oleic acid or halothane, an active expiratory glottic closure was recorded in all lambs but 1, usually throughout the recording period (60 to 300 min). The active expiratory glottic closure was not inhibited after correction of the hypoxia. We conclude that, in nonsedated lambs, a permeability pulmonary edema induces an active expiratory glottic closure. We hypothesize that the expiratory glottic closure commonly observed in newborns could help to ameliorate the alveolocapillary gas exchange by reopening the flooded alveoli.