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Biomedical subjects

F Costes

Publications and source records attributed to F Costes.

26 records · Page 2Linked to original sources
PubMed1997

Accuracy of an automatic and patient-triggered long-term solid memory ambulatory cardiac event recorder.

This study evaluated the R-Test Evolution, a new type of cardiac event recorder bearing both patient-triggered and automatic capabilities. Its 7-day automatic arrhythmia analysis showed promising clinical advantages, especially when investigating patients with unexplained rare events such as syncope, feeling of weakness or faintness, palpitations, stroke, or in patients inconsistent in their use of patient-triggered recordings.

Arrhythmias, Cardiac↗
PubMed1997

Accuracy of pulse oximetry during intense exercise under severe hypoxic conditions.

There is a growing need to measure arterial oxygen saturation with a non-invasive method during heavy exercise under severe hypoxic conditions. Although the accuracy of pulse oximetry has been challenged by several authors, it has not been done under extreme conditions. The purpose of this study was to evaluate the accuracy of a pulse oximeter (Satllite. Datex, Finland) during exercise under hypoxic conditions where arterial oxygen saturation was below 75%, simulating exercise at extreme altitude. Ten healthy non-smoking men performed two exercise studies of 30 min under normoxia and under hypoxia on two consecutive days. The exercise intensity was 80% of maximal O2 consumption of VO2max. Arterial oxygen saturation measured by pulse oximetry was corrected (SpO2[corr]) according to previously published equations and was compared to arterial oxygen saturation (SaO2) in blood samples taken simultaneously from the radial artery. Reference arterial saturation values ranged from 57.2 to 97.6% for the whole data set. This data set was split according to low (SaO2 < or = 75%) and high (SaO2 > 75%) SaO2 values. The error of pulse oximetry (SpO2[corr]-SaO2) was 2.05 (0.87)% [mean (SD)] and 1.80 (1.81)% for high and low SaO2 values, respectively. SpO2[corr] and SaO2 were highly correlated (r = 0.93, SEE = 1.81) for low values. During high-intensity constant workload under severe hypoxic conditions, once corrected, pulse oximetry provides an estimate of SaO2 with a mean error of 2%. Thus, the correction previously described for SpO2 values above 75% saturation applies also to SpO2 values in the range of 57-75% during exercise under hypoxic conditions.

Adult↗
PubMed1996

Comparison of muscle near-infrared spectroscopy and femoral blood gases during steady-state exercise in humans.

Near-infrared spectroscopy (NIRS) is a noninvasive way of measuring muscular oxygenation. We evaluated the relationship between NIRS signal [infrared muscle oxygen saturation (IR-SO2mus)] and the femoral venous oxygen saturation (SfvO2) during cycling exercise. Six healthy subjects performed a 30-min steady-state exercise at 80% maximal oxygen uptake in normoxia and hypoxia (inspired O2 fraction = 0.105). IR-So2mus was recorded continuously throughout the tests with the NIRS probe located on the vastus lateralis. During exercise, blood samples were withdrawn every 5 min from radial artery and femoral vein catheters. In normoxia, IR-So2mus initiated a transient nonsignificant decrease at 5 min, then returned to preexercise level, whereas SfvO2 showed a fast decrease, reaching 18% saturation at 10 min without further change. By contrast, in hypoxia, IR-SO2mus and SfvO2 demonstrated a parallel decrease then stabilized at 10 min. We conclude that IR-SO2mus appears to parallel SfvO2 when both the arterial and venous oxygen contents decrease during steady-state exercise in hypoxia, whereas IR-SO2mus does not follow SfvO2 change in normoxia.

Adult↗
PubMed1995

Efficacy of tracheal and bronchial stent placement on respiratory functional tests.

Stent placement is the only available treatment in patients presenting either a localized external compression or a malacia of the tracheobronchial tree. To assess the functional benefit of prosthesis insertion in these indications, we compared functional respiratory values before, immediately after (48 h), and at sometime after (mean, 10.1 months) operation in 24 patients presenting with a bronchial lesion (B group, n = 5) or a lesion of the intrathoracic part (ITT group, n = 9) or of the extrathoracic part of the trachea (ETT group, n = 10). Before treatment, airflow was severely impaired in most patients without significant differences among the groups. After prosthesis insertion, airflow parameters increased [change in forced expiratory volume in 1 s (delta FEV1 = 440 mL; delta peak expiratory flow (PEF) = 0.92 L.s-1; delta maximum expiratory flow 25/75 (delta MEF25/75) = 0.47 L.s-1; and delta forced inspiratory volume in 1 s (delta FIV1 = 310 mL)] and airway resistances (Raws) decreased (delta Raw = -0.43 kPa.s-1.s-1) without any significant variation in either forced vital capacity (FVC) or total lung capacity. Airflow improvement was more apparent in ITT and ETT groups than in the B group. Moreover, inspiratory flow increase and decrease of FEV1/PEF ratio were only observed in the ETT group. This airflow improvement was maintained for a long time after and was associated with a good clinical tolerance. This study supports the clinical and functional benefits of prosthesis placement both in benign and malignant airway compressions for palliative treatment.

Adult↗
PubMed1995

[Study of chemosensitivity in patients believed to have sleep apnea syndrome].

We performed polysomnography and measured hypoxic ventilatory (HVR), hypercapnic ventilatory responses (HCVR) in 42 patients (60 +/- 11 years) with obesity and a clinical suspicion of sleep apnea syndrome (SAS) in order to determine whether an altered chemosensitivity was associated with SAS. The apnea/hypopnea index was 38 +/- 20 events per hour of sleep in 28 patients (SAS+ group) and less than 10 in the 14 others (SAS- group). The 2 groups differed only by a lower waking PaO2 in SAS+ as compared to SAS- (71.0 +/- 9 vs 77.4 +/- 8 mmHg, p < 0.05). HVR and HCVR were not significantly different in the 2 groups (0.82 +/- 0.58 vs 0.86 +/- 0.37 l.min-1.%-1; 1.41 +/- 0.81 vs 1.40 +/- 0.67 l.min-1.mmHg-1, respectively). In SAS+ group, HVR or HCVR did not change 3 or 12 months after continuous positive airway pressure (CPAP) therapy while both polysomnography and PaO2 returned to normal. We conclude that in patients with mild obesity and SAS there is no difference in chemosensitivity due to the presence of sleep apnea and that CPAP therapy does not alter these measurements. These results suggest no direct effect of SAS on chemosensitivity in the population studied.

Aged↗
PubMed1993

[Postoperative respiratory function and cholecystectomy by laparoscopic approach].

Open cholecystectomy is associated with characteristic changes in pulmonary function showing a restrictive pattern. Laparoscopic cholecystectomy without opening of the peritoneal cavity could be an alternative in reducing postoperative respiratory dysfunction. Having given their informed consent, 13 healthy ASA1 patients (age: 41 +/- 18 yrs) undergoing laparoscopic cholecystectomy were enrolled in this study, in order to assess their postoperative pulmonary function tests (forced vital capacity [FRC], forced expiratory volume [FEV1], functional residual capacity [FRC]) before operation (T0) and 4 h (T4), 24 h (T24), 48 h (T48) after surgery. Anaesthesia technique was the same associating propofol-atracurium-fentanyl, 50% N2O/O2. Ventilation was adapted to maintain end-tidal carbon dioxide pressure up to 30-35 mmHg. Postoperative analgesic regimen consisted of paracetamol-ketoprofen. Mean length of surgery was 84 +/- 15 min; mean duration of anaesthesia was 110 +/- 24 min. An immediate and harmonious restrictive breathing pattern developed postoperatively. Postoperative FVC measured 65% (T4), 63% (T24), 72% (T48) of preoperative function (p < 0.025); postoperative FEV1 measured respectively 60, 66 and 75% of preoperative function (p > 0.001), without change in FEV1/CV and FRC; a significant hypoxia occurred (T0: 86 mmHg, T4: 80 mmHg, T24: 75 mmHg, T48: 81 mmHg [p < 0.05]). Laparoscopic cholecystectomy resulted in less postoperative respiratory dysfunction than conventional cholecystectomy, as previously reported; this restrictive pattern observed without changes in FRC was similar to that following lower abdominal surgery.

Adult↗
PubMed1992

Improvement in exercise performance by inhalation of methoxamine in patients with impaired left ventricular function.

BACKGROUND: Bronchial hyperresponsiveness to cholinergic stimuli such as the inhalation of methacholine is common in patients with impaired left ventricular function. Such hyperresponsiveness is best explained by cholinergic vasodilation of blood vessels in the small airways, with extravasation of plasma due to high left ventricular filling pressure. Because this vasodilation may be prevented by the inhalation of the vasoconstrictor agent methoxamine, we studied the effect of methoxamine on exercise performance in patients with chronic left ventricular dysfunction. METHODS: We studied 19 patients with a mean left ventricular ejection fraction of 22 +/- 4 percent and moderate exertional dyspnea. In the first part of the study, we performed treadmill exercise tests in 10 patients (group 1) at a constant maximal workload to assess the effects of 10 mg of inhaled methoxamine on the duration of exercise (a measure of endurance). In the second part of the study, we used a graded exercise protocol in nine additional patients (group 2) to assess the effects of inhaled methoxamine on maximal exercise capacity and oxygen consumption. Both studies were carried out after the patients inhaled methoxamine or placebo given according to a randomized, double-blind, crossover design. RESULTS: In group 1, the mean (+/- SD) duration of exercise increased from 293 +/- 136 seconds after the inhalation of placebo to 612 +/- 257 seconds after the inhalation of methoxamine (P = 0.001). In group 2, exercise time (a measure of maximal exercise capacity) increased from 526 +/- 236 seconds after placebo administration to 578 +/- 255 seconds after methoxamine (P = 0.006), and peak oxygen consumption increased from 18.5 +/- 6.0 to 20.0 +/- 6.0 ml per minute per kilogram of body weight (P = 0.03). CONCLUSIONS: The inhalation of methoxamine enhanced exercise performance in patients with chronic left ventricular dysfunction. However, the improvement in the duration of exercise at a constant workload (endurance) was much more than the improvement in maximal exercise capacity assessed with a progressive workload. These data suggest that exercise-induced vasodilation of airway vessels may contribute to exertional dyspnea in such patients. Whether or not inhaled methoxamine can provide long-term benefit in patients with heart failure will require further study.

Administration, Inhalation↗