The 3CPO trial suggests that noninvasive ventilation of patients with acute cardiogenic pulmonary edema shortens the initial recovery period but does not change mortality, according to a presentation at the annual meeting of the European Society of Cardiology.

Numerous small studies of 20 to 50 patients have suggested that increasing oxygen pressure may help improve outcome. Noninvasive ventilation can be performed by using continuous positive pressure ventilation or intermittent positive pressure ventilation. The trial was designed to see whether noninvasive ventilation can improve survival and which method should be used. Since the study started, several papers have suggested that the total evidence to date indicates noninvasive ventilation should halve the death rate.

The 3CPO trial, led by Dr Alasdair Gray, was undertaken over three years in 26 Emergency Departments across the UK and recruited over 1,000 patients. At the close of the trial, 1,069 patients had been enrolled and received standard oxygen (367 patients), continuous positive airway pressure (346 patients) or noninvasive intermittent positive pressure ventilation (356 patients).

Compared with standard oxygen treatment, both forms of noninvasive ventilation produced better rates of recovery with a more rapid fall in respiration and heart rate as well as a quicker resolution of acidosis. However, the death rate did not differ. Method of noninvasive ventilation did not change responses.

This first major large-scale clinical trial demonstrated that noninvasive ventilation is a useful treatment to alleviate distress and improve breathing, but it does not improve subsequent chances of survival.