Monitoring long-term nocturnal non-invasive ventilation for chronic hypercapnic respiratory failure: What are the basic tools?

Abstract

Neuromuscular disorders, obesity, and chest wall disorders can lead to chronic hypercapnic respiratory failure. Non-invasive ventilation (NIV) is used for long-term treatment of these patients. In this thesis, we have shown that it is feasible and important to evaluate the presence of undesired nocturnal respiratory events during NIV. We found that transcutaneous CO2 (PtcCO2) is an accurate tool for monitoring PaCO2 and can be used to detect sleep hypoventilation. In addition, respiratory polygraphy during NIV can be used to detect apnea/hypopnea and patient-ventilator asynchrony (PVA). We found that sleep hypoventilation, hypopnea, and PVA are frequent, often without generating symptoms. A test panel, suggested in a European consensus report, proved to have insufficient accuracy in detecting these events. Also, we observed that daytime arterial blood gases and nocturnal SpO2 are insufficient tests to detect sleep hypoventilation. Obstructive hypopnea was the most frequent event and could be accurately detected by a built-in sensor in the ventilator (AHIsoftware). Therefore, PtcCO2 and evaluation of AHIsoftware should be implemented in the routine follow-up of these patients.