Continuous positive airways pressure therapy and cardiovascular dysautonomia among obstructive sleep apnea patients in Yaoundé, Cameroon: a pilot study

Objective We aimed to study the association between cardiovascular dysautonomia and CPAP in patients with obstructive sleep apnea in Yaoundé, Cameroon. Methods From December 2020 to May 2021, we enrolled obstructive sleep apnea patients, treated with CPAP (CPAP+) or not (CPAP-). We assessed cardiovascular dysautonomia using functional tests (deep breathing, stand test and orthostatic hypotension) and heart rate variability (HRV). The latter was studied using the Kubios HRV Standard 3.5.0 software, and included low frequency (LF), high frequency (HF) and LF/ HF ratio. We compared qualitative and quantitative variables between the two patient groups with the Fisher exact and Wilcoxon tests respectively. The significance threshold was set at p < 0.05 . Results We enrolled 8 CPAP + and 11 CPAP-, with median ages (25th, 75th percentiles) 55.5 (52.6, 60.7) and 59 (53.0, 64.0) years respectively. CPAP therapy was associated with LF area (p = 0.033), HF area (p = 0.041) and heart rate difference on deep breathing test (p = 0,006). All patients had at least one feature of cardiovascular dysautonomia. Compared to CPAP+, CPAP- presented a greater proportion of abnormal LF (72.7% vs 25.0%, p = 0.069), HF (63.64% vs 12.5%, p = 0.058), deep breathing (100.0% vs 75.0%, p = 0.163) and stand test (100.0% vs 62.5%, p = 0.058), SNS dysautonomia (72.7% vs 37.5%, p = 0.122) and PNS dysautonomia (100.0% vs 87.5%, p = 0.421). Conclusion In this small sample size pilot study, CPAP + patients presented greater LF and HF powers, and higher average heart rate difference on deep breathing test. Regarding single features, only decreased LF was lower in CPAP + compared to CPAP-.