Effects of nasal high flow on sympathovagal balance, sleep, and sleep-related breathing in patients with precapillary pulmonary hypertension

Abstract

Background In precapillary pulmonary hypertension (PH), nasal high flow therapy (NHF) may favorably alter sympathovagal balance (SVB) and sleep-related breathing through washout of anatomical dead space and alleviation of obstructive sleep apnea (OSA) due to generation of positive airway pressure. Objectives To investigate the effects of NHF on SVB, sleep, and OSA in patients with PH, and compare them with those of positive airway pressure therapy (PAP). Methods Twelve patients with PH (Nice class I or IV) and confirmed OSA underwent full polysomnography, and noninvasive monitoring of SVB parameters (spectral analysis of heart rate, diastolic blood pressure variability). Study nights were randomly split into four 2-h segments with no treatment, PAP, NHF 20 L/min, or NHF 50 L/min. In-depth SVB analysis was conducted on 10-min epochs during daytime and stable N2 sleep at nighttime. Results At daytime and compared with no treatment, NHF20 and NHF50 were associated with a flow-dependent increase in peripheral oxygen saturation but a shift in SVB towards increased sympathetic drive. At nighttime, NHF20 was associated with increased parasympathetic drive and improvements in sleep efficiency, but did not alter OSA severity. NHF50 was poorly tolerated. PAP therapy improved OSA but had heterogenous effects on SVB and neutral effects on sleep outcomes. Hemodynamic effects were neutral for all interventions. Conclusions In sleeping PH patients with OSA NHF20 but not NHF50 leads to decreased sympathetic drive likely due to washout of anatomical dead space. NHF was not effective in lowering the apnea-hypopnoea index and NHF50 was poorly tolerated.

Effects of hyperventilation length on muscle sympathetic nerve activity in healthy humans simulating periodic breathing

“…HRV (expressed as ms 2 based on continuously recorded variability in RR intervals) reflects sympathovagal balance and heart-brain interactions. Data were computed by frequency domain analysis and presented as the high frequency component (HF; 0.15–0.40 Hz), the low frequency component (LF; 0.04–0.15 Hz) and their relative ratio (LF/HF) ( ESC Guidelines, 1996 ; Davies et al, 1999 ; Karemaker, 2017 ; Woehrle et al, 2017 ; Spiesshoefer et al, 2020 ; Spiesshoefer et al, 2021 ).…”

State-of-the-Art Opinion Article on Ventilator-Induced Diaphragm Dysfunction: Update on Diagnosis, Clinical Course, and Future Treatment Options

“…This could represent a problem that warrants future research to advance understanding because the impact of potentially ventilating the lungs against the intrinsic activity of the diaphragm in onethird of all breaths remains uninvestigated. Studying the physiological impact of something as complex as asynchronous MV would likely necessitate analyses of not only respiratory and ventilatory, but also cardiovascular, parameters, as indicated in other works by our group [46][47][48].…”