Analyse de données médicales

@article{pmid32116800,

title = {Hyperoxia During Exercise: Impact on Adenosine Plasma Levels and Hemodynamic Data},

author = {Alain Boussuges and Sarah Rives and Marion Marlinge and Guillaume Chaumet and Nicolas Vallée and Régis Guieu and Olivier Gavarry},

doi = {10.3389/fphys.2020.00097},

issn = {1664-042X},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {Front Physiol},

volume = {11},

pages = {97},

abstract = {INTRODUCTION: Adenosine is an ATP derivative that is strongly implicated in the cardiovascular adaptive response to exercise. In this study, we hypothesized that during exercise the hyperemia, commonly observed during exercise in air, was counteracted by the downregulation of the adenosinergic pathway during hyperoxic exposure.



METHODS: Ten healthy volunteers performed two randomized sessions including gas exposure (Medical air or Oxygen) at rest and during exercise performed at 40% of maximal intensity, according to the individual fitness of the volunteers. Investigations included the measurement of adenosine plasma level (APL) and the recording of hemodynamic data [i.e., cardiac output (CO) and systemic vascular resistances (SVR) using pulsed Doppler and echocardiography].



RESULTS: Hyperoxia significantly decreased APL (from 0.58 ± 0.06 to 0.21 ± 0.05 μmol L,  < 0.001) heart rate and CO and increased SVR in healthy volunteers at rest. During exercise, an increase in APL was recorded in the two sessions when compared with measurements at rest (+0.4 ± 0.4 vs. +0.3 ± 0.2 μmol L for medical air and oxygen exposures, respectively). APL was lower during the exercise performed under hyperoxia when compared with medical air exposure (0.5 ± 0.06 vs. 1.03 ± 0.2 μmol L, respectively  < 0.001). This result could contribute to the hemodynamic differences between the two conditions, such as the increase in SVR and the decrease in both heart rate and CO when exercises were performed during oxygen exposure as compared to medical air.



CONCLUSION: Hyperoxia decreased APLs in healthy volunteers at rest but did not eliminate the increase in APL and the decrease in SVR during low intensity exercise.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31156454,

title = {Mental Workload Alters Heart Rate Variability, Lowering Non-linear Dynamics},

author = {Stéphane Delliaux and Alexis Delaforge and Jean-Claude Deharo and Guillaume Chaumet},

doi = {10.3389/fphys.2019.00565},

issn = {1664-042X},

year  = {2019},

date = {2019-01-01},

urldate = {2019-01-01},

journal = {Front Physiol},

volume = {10},

pages = {565},

abstract = {Mental workload is known to alter cardiovascular function leading to increased cardiovascular risk. Nevertheless, there is no clear autonomic nervous system unbalance to be quantified during mental stress. We aimed to characterize the mental workload impact on the cardiovascular function with a focus on heart rate variability (HRV) non-linear indexes. A 1-h computerized switching task (letter recognition) was performed by 24 subjects while monitoring their performance (accuracy, response time), electrocardiogram and blood pressure waveform (finger volume clamp method). The HRV was evaluated from the beat-to-beat RR intervals (RRI) in time-, frequency-, and informational- domains, before (Control) and during the task. The task induced a significant mental workload (visual analog scale of fatigue from 27 ± 26 to 50 ± 31 mm,  < 0.001, and NASA-TLX score of 56 ± 17). The heart rate, blood pressure and baroreflex function were unchanged, whereas most of the HRV parameters markedly decreased. The maximum decrease occurred during the first 15 min of the task (P1), before starting to return to the baseline values reached at the end of the task (P4). The RRI dimension correlation (D2) decrease was the most significant (P1 vs. Control: 1.42 ± 0.85 vs. 2.21 ± 0.8,  < 0.001) and only D2 lasted until the task ended (P4 vs. Control: 1.96 ± 0.9 vs. 2.21 ± 0.9,  < 0.05). D2 was identified as the most robust cardiovascular variable impacted by the mental workload as determined by posterior predictive simulations ( = 0.9). The Spearman correlation matrix highlighted that D2 could be a marker of the generated frustration ( = -0.61,  < 0.01) induced by a mental task, as well as the myocardial oxygen consumption changes assessed by the double product ( = -0.53,  < 0.05). In conclusion, we showed that mental workload sharply lowered the non-linear RRI dynamics, particularly the RRI correlation dimension.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31281261b,

title = {High Bubble Grade After Diving: The Role of the Blood Pressure Regimen},

author = {Alain Boussuges and Guillaume Chaumet and Nicolas Vallée and Jean Jacques Risso and Jean Michel Pontier},

doi = {10.3389/fphys.2019.00749},

issn = {1664-042X},

year  = {2019},

date = {2019-01-01},

urldate = {2019-01-01},

journal = {Front Physiol},

volume = {10},

pages = {749},

abstract = { Previous studies have suggested that the circulatory system was involved in the production of circulatory bubbles after diving. This study was designed to research the cardio-vascular function characteristics related to the production of high bubble grades after diving.  Thirty trained divers were investigated both at baseline and after a 30-msw SCUBA dive. At baseline, the investigations included blood pressure measurement, echocardiography, and assessment of aerobic fitness using VO peak measurement. Blood samples were taken at rest, to measure the plasma concentration of NOx and endothelin-1. After diving, circulating bubbles were detected in the pulmonary artery by pulsed Doppler at 20-min intervals during the 90 min after surfacing. The global bubble quantity production was estimated by the KISS index.  Divers with a high bubble grade (KISS > 7.5) had systolic blood pressure, pulse pressure, weight, and height significantly higher than divers with a low bubble grade. By contrast, total arterial compliance, plasma NOx level, and percentage of predicted value of peak oxygen uptake were significantly lower in divers with a high bubble grade. Cardiac dimensions, left ventricular function, and plasma endothelin-1 concentration were not significantly different between groups. The multivariate analysis identified blood pressure as the main contributor of the quantity of bubble production. The model including pulse pressure, plasma NOx level, and percentage of predicted value of peak oxygen uptake has an explanatory power of 49.22%.  The viscoelastic properties of the arterial tree appeared to be an important contributor to the circulating bubble production after a dive.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}