Abstract
NIV is effective to treat respiratory failure. Sometimes, the effects of NIV are less than expected. Abnormal events (AE) including upper airway obstruction with (UAO/IE+) or without (UAO/IE-) inspiratory efforts, leaks or asynchrony (ASY), can occur that may affect NIV efficacy on hypercapnia and nocturnal desaturation. PG can detect these events
Objectives: 1) Describe and score AE in patients treated by NIV for respiratory failure related to neuromuscular (NMD), parenchymal (PAR) and thoracic disorders (THO). 2) Evaluate their relationship with ventilator settings, type of mask, clinical status at the time of PG (performed at NIV initiation either in the acute setting or electively, or at steady state), and their consequences on nocturnal SaO2 and daytime PaCO2.
Methods: Observational study. Demographic and functional data, ventilator's settings, ABG and PG's results (SaO2, events) were collected
Results: We analysed 123 PG performed in patients on NIV (65.7±16 y; 57 men, 46 PAR, 48 THO, 29 NMD). Median % time spent with events was 11.5 (4.5-27 %) and was longer in THO (p<0,04). Ventilator settings do not influence the incidence of events. Events are more frequent in the acute setting (p<0,04). Facial mask was associated with more UAO/IE+ (p<0.007). A greater number of events was associated with higher PaCO2 (p<0,03) and lower nocturnal SaO2 (p<0,001). Among the AE, UAO/IE+ (p<0,01) and ASY (p<0,003) were correlated to hypercapnia (p<0,003) whereas desaturation was only correlated to ASY (p<0,002).
Conclusion: AE under NIV are frequent and associated with daytime hypercapnia and nocturnal desaturation. PG is useful to monitor NIV efficacy.
- © 2014 ERS