TY - JOUR T1 - Recovery from dynamic exercise dissociates ventilatory from pulmonary gas exchange responses in patients with chronic thromboembolic pulmonary hypertension JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P5148 AU - Roberta Ramos AU - Eloara Ferreira AU - Arakaki-Ota Jaquelina AU - Luiz Nery AU - J. Alberto Neder AU - Erika Treptow Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P5148.abstract N2 - Background: Exercise is characterized by an excessive ventilatory (V'E) response to metabolic demand (i.e., CO2 output, V'CO2) in chronic thromboembolic pulmonary hypertension (CTEPH). We investigated whether this would also be the case when the neural ventilatory drive (by "feed-forward" mechanisms) is likely to be reduced, e.g, immediately after exercise. Methods: Forty-three patients with CTEPH (50 ± 13 yrs, cardiac index= 2.0 ± 0.5 L/kg/min-1; PVR= 1034 ± 402 dynes.s.cm-2) and 21 sedentary controls performed a ramp-incremental exercise test followed by unloaded recovery. Results: In patients, V'CO2 (and O2 uptake) kinetics were significantly delayed compared to V'E (1st min decrease in % peak values= 13 ± 7 vs 19 ± 1%; 2nd min= 26 ± 13 vs 33 ± 12%; 3rd min= 46 ± 12 vs 53 ± 10 %; 4th min= 54 ± 13 vs 59 ± 13%; 5th min= 61 ± 11 vs 65 ± 4%, p<0.05). This sharply contrasted with results found in the controls in whom V'E kinetics were consistenly slower than V'CO2 throughout the recovery (p<0.05). Consequently, V'E/V'CO2 ratio decreased (and end-tidal CO2 (PETCO2) increased) as exercise ceased in 41/43 (95%) patients with opposite patterns (i.e, V'E/V'CO2 increase and PETCO2 decrease) been found in all controls. Conclusion: Exercise recovery dissociates ventilatory to pulmonary gas exchange responses in patients with CTEPH. Although this might be related to lower post-exercise metabolic drive due to less lactacidosis in patients than controls, it might also indicate that enhanced neural drive - which was suddently reduced at exercise cessation- contributes to patients' excessive exercise V'E. ER -