The use of the cyclical sigh function in long term non-invasive ventilation (NIV) as a method of lung volume recruitment to control hypercapnia in a patient with severe chronic obstructive pulmonary disease (COPD)

Abstract

Rationale: A common cause of hypercapnic respiratory failure in patients with severe COPD is nocturnal hypoventilation. Dreher et al. (Thorax 2010;65: 303-308) found high intensity NIV (HI-NIV) to be superior at controlling hypoventilation in this population. Long term ventilation is only considered to be effective in stable COPD if a specified decrease in pCO2 is demonstrated. Effective ventilation is necessary to prevent mortality associated with severe exacerbations.

Background: A 77 year old lady diagnosed with severe COPD (MRC score 5) 5 years ago. Despite commencement of NIV in a pressure control mode with settings of IPAP 27 EPAP 3 Ti 1.20 Rate 16, after 12 weeks she remained hypercapnic with little change in pCO2 of 7.97kpa. She was unable to tolerate a higher IPAP to support more adequate ventilation due to discomfort.

Objective: To ascertain if the use of the cyclical sigh breath can improve ventilation further than high intensity ventilation alone.

Methods: A cyclical sigh breath of 33cmH₂0 was activated on the (Nippy 3+) ventilator, programmed to deliver once every 30 breaths whilst used nocturnally.

Results: After 4 weeks, daytime capillary gas demonstrated improvement in CO2 clearance (pCO2 - 7.20kpa) with no ventilation discomfort reported.

Conclusion: This case study suggests the use of the cyclical sigh function prevented de-recruitment during sleep and reduced pCO2 levels further than HI-NIV alone. It could be considered in cases where ventilation need and patient discomfort are problematic. Frequency of sigh should be considered as to not distrub sleep.