Heart rate and blood pressure values during a 3-week intermittent hypoxia breathing program in patients with mild COPD

Background and objectives: Intermittent hypoxia (IH) has been proposed as a therapeutic tool in several diseases [Serebrovskaya, High Alt Med Biol 3:205-221, 2002; Burtscher et al., Respir Physiol Neurobiol 165:97-103, 2009; Burtscher et al., Int J Cardiol 96:247-254, 2004]. But it is also known that severe and long lasting repeated hypoxic episodes (e.g. during obstructive sleep apnea) may elevate muscle sympathetic nerve activity and are associated with an increased hypertension risk [Cutler et al., J Appl Physiol 96:754-776, 2004]. Most of the published studies have focused on cardiovascular parameters prior to and after an IH breathing program. In contrast to these studies, the aim of the present analysis was to provide data on cardiovascular responses of patients in the course of an IH breathing program. Methods: Sixteen patients with mild COPD were randomly assigned in a double-blind fashion to a hypoxia (HG, 50± 9 years) or a control group (CG, 56±11 years). Both groups carried out a 3-week breathing program (five sessions per week). During each session, three to five breathing cycles (3 to 5 min, interspersed by 3-min normoxic periods) were completed. The HG received hypoxic air (FiO2 0.15-0.12) during the breathing cycles whereas the CG received normoxic air. HR and BP were recorded before (a) and during the last 30 s of each breathing cycle (b). Differences (b - a) of the 9 to 15 weekly cycles were averaged for heart rate (HRdiff) and systolic and diastolic blood pressure (sBPdiff and dBPdiff). Statistical analyses were performed by paired (within groups) and unpaired (between groups) t tests. Results: HRdiff increased in the HG during the IH programme whereas it remained unchanged in the CG (p=0.004 between groups from weeks 1 to 3). No differences between or within groups were detected for sBPdiff and dBPdiff (Table 1). (Table presented) Conclusion: The increase in HRdiff during the 3 weeks in the HG might be due to the progressive hypoxia (FiO2 0.15 in the first week to 0.12 in the third week) and the resulting higher sympathetic activation. Differences in HRdiff were significant between the HG and the CG, but the applied IH protocol does not seem to provoke clinically relevant changes in the determined parameters.