Most likely to benefit – COPD or hypercapnic acute cardiogenic pulmonary edema
Caution in severely hypoxemic patients
- Delay in endotracheal intubation should not occur because of NIPPV
- Favorable response is usually apparent in the first 2 hours
- Key is appropriately selecting the right patients for NIPPV
COPD
2004 Cochrane database review showed decrease in mortality, decreased intubation, and faster clinical improvement associated with NIPPV.
Dangers of inadequate ventilation
- Transdiaphragmatic pressure generation is high -> risk of respiratory muscle fatigue
Acute cardiogenic pulmonary edema
Decreases work of breathing and improves cardiovascular function
Cardiovascular function
- Decreases LV afterload
- Reduces RV and LV preload
3CPO study showed that in patients with clinical dx of CPE (RR > 30, pH < 7.35, CXR w/ edema) randomized to NIPPV or standard oxygen tx had improved physiologic outcomes with NIPPV, but no difference in intubation rates and 7 and 30 day mortality.
- Crossover – There was a high incidence of crossover (~15%) from the standard oxygen group. This could make argument that higher rates of intubation could have happened in standard oxygen group.
- Sick patients excluded – Severely ill patients w/ need for lifesaving intervention were excluded.
- CPAP vs. PSV+PEEP – Similar outcomes (re: intubation, mortality, clinical changes) between the two modes of NIPPV.
Hypoxemic respiratory failure
Difference between CPAP and PSV+PEEP
CPAP
- Early benefit with dyspnea and oxygenation
- But, no difference with ETI, mortality, or ICU LOS
- CPAP alone not recommended in mild to severe ARDS
PSV+PEEP
- Multiple RCTs (Martin 2000, Ferrer 2003) found benefits regarding intubation and mortality. Though importantly these studies had heterogenous patient populations with ARDS from multiple etiologies.
- Despite some benefit seen in the studies above, there have been high rates of NIPPV failure in PNA and severe hypoxemia patients (Meduri 1996, Jolliet 2001, Domenighetti 2002, Antonelli 2001).
