Nighttime nasal high flow therapy (NHF) at 20 L/min reduced sympathetic drive, most likely through washout of anatomical dead space, in patients with precapillary pulmonary hypertension (PH) and obstructive sleep apnea (OSA), according to study results published in Sleep and Breathing.
Pharmacologic treatment of PH may restore sympathovagal balance (SVB), at least partially. Therefore, researchers from Europe and the United States investigated the effects of NHF on SVB, OSA, and sleep in patients with PH and compared this treatment option to positive airway pressure (PAP) therapy.
A total of 12 patients (age, 68.4±11.1 years) with Nice class 1 pulmonary arterial hypertension of class 4 chronic thromboembolic PH and confirmed OSA were included in the study. Only patients with PH and sleep-disordered breathing (SDB) with predominant OSA were recruited. All patients underwent full diagnostic polysomnography to identify SDB with predominant OSA. Predominant OSA was defined as an apnea hypopnea index ≥10/h, with ≥50% of apneic events being obstructive.
Investigators also performed noninvasive monitoring of SVB parameters, including spectral analysis of heart rate and diastolic blood pressure variability. To study the effects of NHF at nighttime, study nights were split into 4 parts, with each part consisting of a 2-hour duration. The first part consisted of no treatment of SDB. Then, automatic PAP, NHF at 20 L/min (NHF20), and NHF 50 L/min (NHF50) were administered for 2 hours each in a randomized fashion. The investigators conducted an in-depth SVB analysis on 10-minute epochs during the day and stable N2 (nonrapid eye movement stage 2) sleep at nighttime.
Compared with no treatment, both NHF20 and NHF50 were associated with a flow-dependent increase in peripheral oxygen saturation at daytime. No change in hemodynamic parameters was observed during NHF20 compared with no treatment. There was a shift towards predominance of parasympathetic drive over sympathetic drive during N2 sleep. Additionally, NHF20 was associated with improvements in sleep efficiency and increased parasympathetic drive at nighttime, whereas NHF50 was poorly tolerated. Treatment with NHF20 was not associated with alterations in OSA severity. Treatment with PAP improved OSA.
Limitations of this study included its small sample size, the limited duration of interventions, and the lack of invasive measurement for sympathetic drive.
The investigators added that additional long-term studies “of NHF20 are needed to test whether this intervention favorably alters sympathetic drive and improves the functional status of patients with precapillary PH.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Spiesshoefer J, Bannwitz B, Mohr M, et al. Effects of nasal high flow on sympathovagal balance, sleep, and sleep-related breathing in patients with precapillary pulmonary hypertension. Sleep Breath. Published online August 22, 2020. doi:10.1007/s11325-020-02159-1