Effect of sleep on patient/ventilator asynchrony in patients undergoing chronic non-invasive mechanical ventilation

Respir Med. 2007 Aug;101(8):1702-7. doi: 10.1016/j.rmed.2007.02.026. Epub 2007 Apr 19.


Background: Patients who require home non-invasive ventilation (NIV) during sleep normally have the ventilation settings adjusted empirically during daytime wakefulness. However, patient-ventilator asynchrony may occur during sleep. To detect the incidence of ineffective efforts (IE) during the sleep compared to wakefulness, we studied 48 patients already enrolled in a long-term home NIV programme.

Methods: We evaluated arterial blood gases, breathing pattern during spontaneous breathing (SB) and ventilation during wakefulness. In addition, we assessed the breathing pattern and oxygen gas exchange during night-time NIV.

Results: Daytime NIV significantly improved blood gases compared to SB (PaO2 NIV 10.2 +/- 1.95 kPa vs PaO2 SB 8 +/- 1.37, p < 0.001; PaCO2 NIV 5.75 +/- 1.08 kPa, vs PaCO2 SB 6.5 +/- 1.25, p < 0.001). The IE index was higher during sleep compared to wakefulness (48 +/- 39.5 events/h versus 0 +/- 0). The IE index was correlated with the time spent with SaO2 < 90% (r = 0.39, p < 0.01), but not with ventilator parameters, underlying disease, ventilation mode or type of mask. Eight patients had an IE index >100 events/h; these patients had a faster respiratory rate, required a higher level of inspiratory assistance and had poor gas exchange during sleep.

Conclusions: We conclude that IE to breath are common during nocturnal NIV and that they may be associated with desaturations even in patients who are considered compliant and effectively treated.

MeSH terms

  • Aged
  • Home Care Services, Hospital-Based
  • Humans
  • Middle Aged
  • Obesity Hypoventilation Syndrome / therapy*
  • Polysomnography
  • Pulmonary Disease, Chronic Obstructive / therapy*
  • Respiration, Artificial / methods*
  • Respiratory Insufficiency / therapy*
  • Sleep / physiology*