Background
Although cardiac autonomic modulation has been studied in several respiratory diseases, the evidence is limited on lung transplantation, particularly on its acute and chronic effects. Thus, we aimed to evaluate cardiac autonomic modulation before and after bilateral lung transplantation (BLT) through a prospective study on patients enrolled while awaiting transplant.
Methods
Twenty-two patients on the waiting list for lung transplantation (11 women, age 33 [24–51] years) were enrolled in a prospective study at Ospedale Maggiore Policlinico Hospital in Milan, Italy. To evaluate cardiac autonomic modulation, ten minutes ECG and respiration were recorded at different time points before (T0) and 15 days (T1) and 6 months (T2) after bilateral lung transplantation. As to the analysis of cardiac autonomic modulation, heart rate variability (HRV) was assessed using spectral and symbolic analysis. Entropy-derived measures were used to evaluate complexity of cardiac autonomic modulation. Comparisons of autonomic indices at different time points were performed.
Results
BLT reduced HRV total power, HRV complexity and vagal modulation, while it increased sympathetic modulation in the acute phase (T1) compared to baseline (T0). The HRV alterations remained stable after 6 months (T2).
Conclusion
BLT reduced global variability and complexity of cardiac autonomic modulation in acute phases, and these alterations remain stable after 6 months from surgery. After BLT, a sympathetic predominance and a vagal withdrawal could be a characteristic autonomic pattern in this population.
The aim of the present study was to investigate the cumulative effects of two bouts of maximal exercise on heart rate (HR) by spectral and detrended fluctuation analysis (DFA). Rowers (n=14, 11 males, 24±6 years old) performed two maximal (2k1 and 2k2) tests. HRV and DFA were calculated before (PRE1) and after 2k1 (POS1), four hours after POS1 (PRE2) and after 2k2 (POS2). The HF power was reduced from PRE1 (1527±1349 ms2) to POS1 (224±339 ms2) and from PRE2 (908±861 ms2) to POS2 (214±234 ms2, respectively, p<0.05) and in PRE2 was lower than PRE1 (p<0.05), with similar reductions in POS1 and POS2 (p>0.05). DFA in the time domain was used as a non‐linear method to quantify HR fluctuations detrended from its nonstationary background, giving a more precise measure of the fractality and long‐range correlations in the time series. DFA analysis is able to assess that HR fluctuations in POS2 were lower that POS1, moreover, the exponent α related to the fractal measure departs from a purely random one (α=0.5), evidencing long‐range correlations in HR variability, with slightly different exponents in PRE and POS groups. DFA showed that after 2k2 there was an additional reduction on HR fluctuations. These data suggest cumulative effects of exercise on HR dynamics and both methods give complementary information.Support: CNPq 481434/2008‐9 and FAPERJ E‐26/111.345/2011
The aim of the present study was to investigate the influence of continuous positive airway pressure (CPAP) on time to exhaustion (TLIM), rating of perceived exertion (RPE) and cardiovascular hemodynamics. Healthy male subjects (n= 10, 24±3 years old and VO2max= 41.09 ± 7.37 mL.kg−1.min−1) performed sustained heavy cycling exercise (80%VO2max) with CPAP (20cmH2O of inspiratory and 0cmH2O of expiratory pressures) and without CPAP (NO‐CPAP). There were two days for protocol adaptation (M1 and M2) and two experimental exercise sessions (M3 and M4) executed in NO‐CPAP and CPAP modes, in random order. Exercise days M3 and M4 were used for calculations. Heart rate (HR), systolic blood pressure (SBP) and cardiac output (CO) were obtained by infrared photopletysmograph. The RPE was determined (Borg, 0–10) for dyspnea (B.dys) and for locomotor muscles (B.loc). With CPAP, TLIM increased (555±67 to 639±127 sec, p<0.05) and B.Dys (8±3 to 6±2, p<0.05) and B.Loc (9±2 to 8±2, p<0.05) were reduced as compared to NO‐CPAP. No differences were found for HR (174±13 and 176± 12 bpm, p> 0.05), SBP (210± 32 and 211±21 mmHg, p> 0.05) and CO (16±5 and 15±5 L.min−1, p> 0.05) for NO‐CPAP and CPAP situations, respectively. CPAP during heavy exercise increased TLIM without presenting hemodynamic changes in healthy subjects.Financial support: CNPq 481434/2008‐9 and FAPERJ E‐26/111.345/2011
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