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This study aimed to investigate the changes in blood viscosity, pulmonary hemodynamics, nitric oxide (NO) production, and maximal oxygen uptake () during a maximal incremental test conducted in normoxia and during exposure to moderate altitude (2,400 m) in athletes exhibiting exercise-induced hypoxemia at sea level (EIH). Nine endurance athletes with EIH and eight without EIH (NEIH) performed a maximal incremental test under three conditions: sea level, 1 day after arrival in hypoxia, and 5 days after arrival in hypoxia (H5) at 2,400 m. Gas exchange and oxygen peripheral saturation (SpO2) were continuously monitored. Cardiac output, pulmonary arterial pressure, and total pulmonary vascular resistance were assessed by echocardiography. Venous blood was sampled before and 3 min after exercise cessation to analyze blood viscosity and NO end-products. At sea level, athletes with EIH exhibited an increase in blood viscosity and NO levels during exercise while NEIH athletes showed no change. Pulmonary hemodynamics and aerobic performance were not different between the two groups. No between-group differences in blood viscosity, pulmonary hemodynamics, and were found at 1 day after arrival in hypoxia. At H5, lower total pulmonary vascular resistance and greater NO concentration were reported in response to exercise in EIH compared with NEIH athletes. EIH athletes had greater cardiac output and lower SpO2 at maximal exercise in H5, but no between-group differences occurred regarding blood viscosity and . The pulmonary vascular response observed at H5 in EIH athletes may be involved in the greater cardiac output of EIH group and counterbalanced the drop in SpO2 in order to achieve similar than NEIH athletes.

The practice of physical activity in a variable climate during the same competition is becoming more and more common due to climate change and increasingly frequent climate disturbances. The main aim of this pilot study was to understand the impact of cold ambient temperature on performance factors during a professional cycling race. Six professional athletes (age = 27 ± 2.7 years; height = 180.86 ± 5.81 cm; weight = 74.09 ± 9.11 kg; % fat mass = 8.01 ± 2.47%; maximum aerobic power (MAP) = 473 ± 26.28 W, undertook ~20 h training each week at the time of the study) participated in the Tour de la Provence under cold environmental conditions (the ambient temperature was 15.6 ± 1.4 °C with a relative humidity of 41 ± 8.5% and the normalized ambient temperature (Tawc) was 7.77 ± 2.04 °C). Body core temperature (Tco) was measured with an ingestible capsule. Heart rate (HR), power, speed, cadence and the elevation gradient were read from the cyclists’ onboard performance monitors. The interaction (multivariate analysis of variance) of the Tawc and the elevation gradient has a significant impact (F(1.5) = 32.2; p < 0.001) on the variables (cadence, power, velocity, core temperature, heart rate) and on each individual. Thus, this pilot study shows that in cold environmental conditions, the athlete’s performance was limited by weather parameters (ambient temperature associated with air velocity) and race characteristics. The interaction of Tawc and elevation gradient significantly influences thermal (Tco), physiological (HR) and performance (power, speed and cadence) factors. Therefore, it is advisable to develop warm-up, hydration and clothing strategies for competitive cycling under cold ambient conditions and to acclimatize to the cold by training in the same conditions to those that may be encountered in competition.

Olympic distance cross-country cycling (XCO) is a discipline subject to wide performance variability due to uncontrollable environmental factors such as altitude, ambient temperature and/or humidity. This study therefore aimed to investigate the impact of environmental factors on XCO performance in under-23 and elite female and male categories. Individual data were collected from Continental Cup, World Cup, World Championship, and Olympics Games for U23 and elite female and male categories from 2009 to 2018. Factors included were race time (range: 55–157 min), average speed (range: 7.6–32.2 km/h), distance (range: 15.2–48.4 km), altitude (range: 50–2680 m), ambient temperature (range 7–41°C), relative and absolute humidity (range: 8–97% and 2.4–25.3 g/m(3), respectively), and categories. The analysis represents 10,966 individual data which indicate a continuous progression of the performance for all categories. Principal component analysis reveals that the slowest XCO performance was resulting from high ambient temperature and absolute humidity. Regressions revealed that only altitude (P

Because progressive respiratory muscle weakness leads to decreased chest-wall motion with eventual ribcage stiffening, the purpose was to compare vital capacity (VC) and contributions of chest-wall compartments before and after volume recruitment–derecruitment manoeuvres (VRDM) in Duchenne muscular dystrophy (DMD). We studied nine patients with DMD and VC lower than 30% of predicted. VRDM was performed using 15 insufflations–exsufflations of +30 to −30 cmH2O. VC and three-dimensional chest-wall motion were measured, as well as oxygen saturation, transcutaneous partial pressure of carbon dioxide and the rapid shallow breathing index (respiratory rate/tidal volume) before (baseline) and immediately and 1 hour after VRDM. VC increased significantly immediately after VRDM (108% ± 7% of baseline, p = 0.018) but returned to baseline within 1 hour, and the rapid shallow breathing index increased significantly. The non-dominant side systematically increased immediately after VRDM ( p = 0.0077), and in the six patients with abnormal breathing asymmetry (difference >10% of VC) at baseline, this asymmetry was corrected immediately and/or 1 hour after VRDM. VRDM improved VC and reduced chest-wall motion asymmetry, but this beneficial effect waned rapidly with respiratory muscle fatigue, suggesting that VRDM may need to be repeated during the day to produce lasting benefits.

Plethysmography is an indispensable component of clinical lung function testing. However, lung volume measurement in the supine position using an optoelectronic system requires the placement of reflective markers on the anterior and lateral torso surface. The conventional method computes breath-by-breath changes in the volume between the markers and the bed, which serves as the reference plane. In contrast, the surface method consists of measuring the volume delineated by the surface area of the marker network at the onset and end of inspiration. We compared these 2 methods to spirometry during spontaneous breathing in 11 healthy volunteers and in 14 patients receiving routine visits for neuromuscular disease. Bland-Altman plots showed that agreement with spirometry was better for the surface method that the conventional method. Our results open up prospects for integrating these methods in the development of new devices.

International audience; : Neurally adjusted ventilator assist (NAVA) assists spontaneous breathing in proportion to diaphragmatic electrical activity (EAdi). Here, we evaluate the effects of various levels of NAVA and PSV on the breathing pattern and, thereby, on [Formula: see text] homeostasis in 10 healthy volunteers. For each ventilation mode, four levels of support (delivered pressure 0 i.e. baseline, 5, 8, and 10cmH2O) were tested in random order. EAdi, flow, and airway pressure were recorded. Optoelectronic plethysmography was used to study lung volume distribution. During both PSV and NAVA, EAdi decreased with the level of assistance (P

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ([Formula: see text]) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with [Formula: see text] by computing the phase angles [Formula: see text] (for SB) and the correlation r (for VC) between them. Analysis of [Formula: see text] and r of the outward translation parameter [Formula: see text] of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities.

Purpose Arterial blood gas measurement is frequently performed in critically ill patients to diagnose and monitor acute respiratory failure. At a given metabolic rate, carbon dioxide partial pressure (Pa co 2) is entirely determined by CO2 elimination through ventilation. Transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring permits a noninvasive and continuous estimation of arterial CO2 tension (Pa co 2). The accuracy of PtcCO2, however, has not been well studied. To assess the accuracy of different CO2 monitoring methods, we compared PtcCO2 and end-tidal CO2 concentration (EtCO2) to Pa co 2 measurements in nonintubated intensive care unit (ICU) patients with acute respiratory failure. Methods During a 2-month period, we conducted a prospective observational cohort study in 25 consecutive nonintubated and spontaneously breathing patients admitted to our ICU. Arterial blood gases were measured at study inclusion, 30, 60, and 120 minutes later. At each sampling time, EtCO2 was continuously monitored using a Philips Smart Capnoline Plus, and PtcCO2 was measured using was measured using SenTec device. The aim of the study was to assess agreement between PtcCO2 and Pa co 2 and between EtCO2 and Pa co 2 in nonintubated ICU patients with acute respiratory failure. Bland-Altman techniques and Pearson correlation coefficients were used. The differences over time (at 30, 60, and 120 minutes) between Pa co 2 and EtCO2 and between PtcCO2 and Pa co 2 were evaluated using 1-way analysis of variance. Results Transcutaneous partial pressure of carbon dioxide and Pa co 2 were well correlated (R = 0.97), whereas the correlation between EtCO2 and Pa co 2 was poor (R = 0.62) probably due to the presence of an alveolar dead space in a few patients, most notably in the group with chronic obstructive pulmonary disease. The difference over time remained stable for both Pa co 2 vs EtCO2 (analysis of variance; P = .88) and Pa co 2 vs PtcCO2 (P = .93). Conclusion We found large differences between EtCO2 and Pa co 2 in spontaneously breathing nonintubated ICU patients admitted for acute respiratory failure. Our study argues against the use of EtCO2 monitoring in such patients but raises the possibility that PtcCO2 measurement may provide reasonable estimates of Pa co 2.

The objective was to determine whether optoelectronic plethysmography (OEP) can detect asymmetric ventilation related to unilateral or asymmetric diaphragmatic weakness, suggesting usefulness as a diagnostic tool.Thirteen patients with suspected asymmetric diaphragmatic weakness based on dyspnea and hemidiaphragm elevation on the chest radiograph were studied as well as three patients with maltase acid deficiency (a cause of symmetrical diaphragmatic weakness). The transdiaphragmatic pressure response to unilateral magnetic stimulation (lateral twitch transdiaphragmatic pressure [latPdiTw]) and the diaphragm compound muscle action potentials (CMAPs) elicited by transcutaneous electrical stimulation of each phrenic nerve as well as OEP were performed.The CMAPs and latPdiTw showed unilateral or predominantly unilateral diaphragmatic weakness in nine of the 13 patients. By OEP, the affected side of the thorax and abdomen contributedlt; 45% of the inspiratory capacity in each of these nine patients, whereas no asymmetry was noted in the other four patients or in the three patients with maltase acid deficiency. All patients preferred OEP over CMAP or latPdiTw.OEP detected asymmetric ventilation in all patients diagnosed with unilateral diaphragm weakness and in no patients without this diagnosis. Thus, OEP is an effective noninvasive alternative that is preferred by the patients over CMAP response and latPdiTw.