Constant infusion transpulmonary thermodilution for the assessment of cardiac output in exercising humans

To determine the accuracy and precision of constant infusion transpulmonary thermodilution cardiac output (CITT-Q) assessment during exercise in humans, using indocyanine green (ICG) dilution and bolus transpulmonary thermodilution (BTD) as reference methods, cardiac output (Q) was determined at rest and during incremental one- and two-legged pedaling on a cycle ergometer, and combined arm cranking with leg pedaling to exhaustion in 15 healthy men. Continuous infusions of iced saline in the femoral vein (n=41) or simultaneously in the femoral and axillary (n=66) veins with determination of temperature in the femoral artery were used for CITT-Q assessment. CITT-Q was linearly related to ICG-Q (r=0.82, CITT-Q=0.876×ICG-Q+3.638, P<0.001; limits of agreement ranging from -1.43 to 3.07L/min) and BTD-Q (r=0.91, CITT-Q=0.822×BTD+4.481L/min, P<0.001; limits of agreement ranging from -1.01 to 2.63L/min). Compared with ICG-Q and BTD-Q, CITT-Q overestimated cardiac output by 1.6L/min (≈10% of the mean ICG and BTD-Q values, P<0.05). For Q between 20 and 28L/min, we estimated an overestimation <5%. The coefficient of variation of 23 repeated CITT-Q measurements was 6.0% (CI: 6.1-11.1%). In conclusion, cardiac output can be precisely and accurately determined with constant infusion transpulmonary thermodilution in exercising humans.5275181,613,331Q1Q1SCI

Femoral fracture during breech vaginal delivery: A case report

International audienc

Cerebral Blood Flow During Sprint Exercise

Se desconocen los efectos del entrenamiento interválico de alta intesidad (HIIT) sobre el flujo sanguíneo cerebral (FSC) y la oxigenación cerebral. Por ello reclutamos a 20 voluntarios que realizaron una sesión de HIIT (4 test de Wingate con recuperaciones de 4 minutos). Se midió la oxigenación del lóbulo frontal (OLF) y el Vastus lateralis (VL) a través de espectrofotometría cercana a los infrarrojos (NIRS). También se registró la velocidad de la sangre en las arterias cerebrales medias (vACM) mediante Doppler. La vACM disminuyó entre un 5 y 10 % en el primer esprint. En los siguientes esprints se redujo aún más. La vACM descendió en cada esprint coincidiendo con la disminución de la presión tele-espiratoria de dióxido de carbono (PETCO2) y con valores superiores de ventilación pulmonar (VE). Al interrumpirse el pedaleo se redujo bruscamente la vACM. Sin embargo, la OLF se mantuvo estable en el primer esprint sólo reduciéndose ligeramente durante el segundo y tercer Wingate (el cuarto fue similar al tercero). Este estudio muestra que la vACM disminuye durante los ejercicios de esprint, posiblemente debido a la hipocapnia. La reducción de la vACM no ejerce efectos funcionales ni relevantes sobre la oxigenación cerebral, gracias al ajuste de la conductancia vascular a través de los mecanismos de autoregulación, sin que parezca afectar negativamente al rendimiento.The effect of high-intensity interval training (HIIT) on cerebral blood flow (CBF) and cerebral oxygenation remain unknown. Therefore, we recruited 20 voluntaries who performed one HIIT session (4x30s Wingate tests with 4 minutes recovery between them). We measured frontal lobe (FLO) and Vastus lateralis (VL) oxygenation with NIRS. Middle cerebral artery blood flow velocity (MCAv) was measured by Doppler. MCAv decreased between 5 and 10 % during the first sprint. MCAv decreased slightly more during the subsequent sprints. Nevertheless, FLO remained stable during the first sprint and was only reduced slightly during the second and third Wingate (the fourth was similar to the third). MCAv decreased on each sprint with the reduction of End-tidal carbon dioxide pressure (PETCO2), the latter due to hyperventilation. When subjects stopped pedaling MCAv was dropped markedly. The decrease in MCAv did not produce any functional or relevant effect on frontal lobe oxygenation due to the adjustment of cerebral vascular conductance by the auto-regulatory mechanisms and did not seem to negatively affect performance.0

Flujo sanguíneo cerebral durante el ejercicio de esprint

The effect of high-intensity interval training (HIIT) on cerebral blood flow (CBF) and cerebral oxygenation remain unknown. Therefore, we recruited 20 voluntaries who performed one HIIT session (4x30s Wingate tests with 4 minutes recovery between them). We measured frontal lobe (FLO) and Vastus lateralis (VL) oxygenation with NIRS. Middle cerebral artery blood flow velocity (MCAv) was measured by Doppler. MCAv decreased between 5 and 10 % during the first sprint. MCAv decreased slightly more during the subsequent sprints. Nevertheless, FLO remained stable during the first sprint and was only reduced slightly during the second and third Wingate (the fourth was similar to the third). MCAv decreased on each sprint with the reduction of End-tidal carbon dioxide pressure (PETCO2), the latter due to hyperventilation. When subjects stopped pedaling MCAv was dropped markedly. The decrease in MCAv did not produce any functional or relevant effect on frontal lobe oxygenation due to the adjustment of cerebral vascular conductance by the auto-regulatory mechanisms and did not seem to negatively affect performance.Se desconocen los efectos del entrenamiento interválico de alta intesidad (HIIT) sobre el flujo sanguíneo cerebral (FSC) y la oxigenación cerebral. Por ello reclutamos a 20 voluntarios que realizaron una sesión de HIIT (4 test de Wingate con recuperaciones de 4 minutos). Se midió la oxigenación del lóbulo frontal (OLF) y el Vastus lateralis (VL) a través de espectrofotometría cercana a los infrarrojos (NIRS). También se registró la velocidad de la sangre en las arterias cerebrales medias (vACM) mediante Doppler. La vACM disminuyó entre un 5 y 10 % en el primer esprint. En los siguientes esprints se redujo aún más. La vACM descendió en cada esprint coincidiendo con la disminución de la presión tele-espiratoria de dióxido de carbono (PETCO2) y con valores superiores de ventilación pulmonar (VE). Al interrumpirse el pedaleo se redujo bruscamente la vACM. Sin embargo, la OLF se mantuvo estable en el primer esprint sólo reduciéndose ligeramente durante el segundo y tercer Wingate (el cuarto fue similar al tercero). Este estudio muestra que la vACM disminuye durante los ejercicios de esprint, posiblemente debido a la hipocapnia. La reducción de la vACM no ejerce efectos funcionales ni relevantes sobre la oxigenación cerebral, gracias al ajuste de la conductancia vascular a través de los mecanismos de autoregulación, sin que parezca afectar negativamente al rendimiento

Cerebral blood flow during sprint exercise

Se desconocen los efectos del entrenamiento interválico de alta intesidad (HIIT) sobre el flujo sanguíneo cerebral (FSC) y la oxigenación cerebral. Por ello reclutamos a 20 voluntarios que realizaron una sesión de HIIT (4 test de Wingate con recuperaciones de 4 minutos). Se midió la oxigenación del lóbulo frontal (OLF) y el Vastus lateralis (VL) a través de espectrofotometría cercana a los infrarrojos (NIRS). También se registró la velocidad de la sangre en las arterias cerebrales medias (vACM) mediante Doppler. La vACM disminuyó entre un 5 y 10 % en el primer esprint. En los siguientes esprints se redujo aún más. La vACM descendió en cada esprint coincidiendo con la disminución de la presión tele-espiratoria de dióxido de carbono (PETCO2) y con valores superiores de ventilación pulmonar (VE). Al interrumpirse el pedaleo se redujo bruscamente la vACM. Sin embargo, la OLF se mantuvo estable en el primer esprint sólo reduciéndose ligeramente durante el segundo y tercer Wingate (el cuarto fue similar al tercero). Este estudio muestra que la vACM disminuye durante los ejercicios de esprint, posiblemente debido a la hipocapnia. La reducción de la vACM no ejerce efectos funcionales ni relevantes sobre la oxigenación cerebral, gracias al ajuste de la conductancia vascular a través de los mecanismos de autoregulación, sin que parezca afectar negativamente al rendimiento.The effect of high-intensity interval training (HIIT) on cerebral blood flow (CBF) and cerebral oxygenation remain unknown. Therefore, we recruited 20 voluntaries who performed one HIIT session (4x30s Wingate tests with 4 minutes recovery between them). We measured frontal lobe (FLO) and Vastus lateralis (VL) oxygenation with NIRS. Middle cerebral artery blood flow velocity (MCAv) was measured by Doppler. MCAv decreased between 5 and 10 % during the first sprint. MCAv decreased slightly more during the subsequent sprints. Nevertheless, FLO remained stable during the first sprint and was only reduced slightly during the second and third Wingate (the fourth was similar to the third). MCAv decreased on each sprint with the reduction of End-tidal carbon dioxide pressure (PETCO2), the latter due to hyperventilation. When subjects stopped pedaling MCAv was dropped markedly. The decrease in MCAv did not produce any functional or relevant effect on frontal lobe oxygenation due to the adjustment of cerebral vascular conductance by the auto-regulatory mechanisms and did not seem to negatively affect performance.Sin financiaciónNo data JCR 2016No data SJR 20160.420 IDR (2016) C2, 17/42 Deport

Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans

Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min−1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced PETCO2, CBF and frontal lobe oxygenation decreased in parallel (r = 0.93, P &amp;lt; 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4–6 mmHg lower PaCO2 in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO2 in hypoxia, leading to a similar brain O2 delivery during the sprints regardless of PIO2. In conclusion, when a conflict exists between preserving brain O2 delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O2 delivery. © 2017, © The Author(s) 2017

Impact of data averaging strategies on V̇O2max assessment: Mathematical modeling and reliability

Background: No consensus exists on how to average data to optimize (Formula presented.) O2max assessment. Although the (Formula presented.) O2max value is reduced with larger averaging blocks, no mathematical procedure is available to account for the effect of the length of the averaging block on (Formula presented.) O2max. Aims: To determine the effect that the number of breaths or seconds included in the averaging block has on the (Formula presented.) O2maxvalue and its reproducibility and to develop correction equations to standardize (Formula presented.) O2max values obtained with different averaging strategies. Methods: Eighty-four subjects performed duplicate incremental tests to exhaustion (IE) in the cycle ergometer and/or treadmill using two metabolic carts (Vyntus and Vmax N29). Rolling breath averages and fixed time averages were calculated from breath-by-breath data from 6 to 60 breaths or seconds. Results: (Formula presented.) O2max decayed from 6 to 60 breath averages by 10% in low fit ((Formula presented.) O2max &apos; 40 mL kg−1 min−1) and 6.7% in trained subjects. The (Formula presented.) O2max averaged from a similar number of breaths or seconds was highly concordant (CCC &apos; 0.97). There was a linear-log relationship between the number of breaths or seconds in the averaging block and (Formula presented.) O2max (R2 &apos; 0.99, P &apos; 0.001), and specific equations were developed to standardize (Formula presented.) O2max values to a fixed number of breaths or seconds. Reproducibility was higher in trained than low-fit subjects and not influenced by the averaging strategy, exercise mode, maximal respiratory rate, or IE protocol. Conclusions: The (Formula presented.) O2maxdecreases following a linear-log function with the number of breaths or seconds included in the averaging block and can be corrected with specific equations as those developed here. © 2019 John Wiley &amp; Sons A/S. Published by John Wiley &amp; Sons Lt