Respiratory failure due to severe cardiogenic pulmonary edema to get either:

• Oxygen alone

• Oxygen plus CPAP via facemask
  

• After 30 minutes, both RR and PaCO2 had decreased more in the patients who received oxygen plus continuous positive airway pressure.
  
• The mean (+/- SD) respiratory rate at 30 minutes decreased from 32 +/- 6 to 33 +/- 9 breaths per minute in the patients receiving oxygen alone and from 35 +/- 8 to 27 +/- 6 breaths per minute in those receiving oxygen plus continuous positive airway pressure (p = 0.008)
• The PaCO2 decreased from 64 +/- 17 to 62 +/- 14 mm Hg in those receiving oxygen alone and from 58 +/- 8 to 46 +/- 4 mm Hg in those receiving CPAP (p < 0.001).
  
• The patients receiving CPAP also had a greater increase in the arterial pH (oxygen alone, from 7.15 +/- 0.11 to 7.18 +/- 0.18; CPAP, from 7.18 +/- 0.08 to 7.28 +/- 0.06; p < 0.001) and in the ratio of arterial oxygen tension to the fraction of inspired oxygen (oxygen alone, from 136 +/- 44 to 126 +/- 47; CPAP, from 138 +/- 32 to 206 +/- 126; P = 0.01).
  
• No significant difference was found in in-hospital mortality (oxygen alone, 4 of 20 patients; CPAP, 2 of 19; P = 0.36) or the length of the hospital stay.

Patients with acute cardiogenic pulmonary edema (orthopnoea, RR > 25 breaths/min, pulse ox < 90% in room air and diffuse crackles):

• Standard treatment alone

• Standard treatment plus CPAP
  

• CPAP was used for 60 min [40, 65] (median [Q1, Q3]) in the pre-hospital setting and 120 min [60, 242] in ICU and was well tolerated in all patients.
  
• Treatment was successful in 79% of patients in the CPAP group and 63% in the control group (p = 0.01), especially for persistence of inclusion criteria after 2 h (12 vs. 26%) and for intubation criteria (4 vs. 14%). CPAP was beneficial irrespective of the initial PaCO(2) or LVEF.

Prospective, Randomized Study

Patients with acute cardiogenic pulmonary edema and respiratory failure to either receive:

• 30% oxygen with a high-flow face mask apparatus at ambient airway pressure
  
• 10 cm H2O of CPAP

• In the first 10 minutes of CPAP treatment, PaO2 increased 8 +/- 9 mm Hg (mean +/- 1 SD), (p < 0.01) and respiratory rate decreased 5 +/- 5 breaths/min (p < 0.001).
  
• Systolic arterial pressure decreased 12 +/- 21 mm Hg (p < 0.05), and heart rate by 10 +/- 11 beats/min (p less than 0.001).
  
• A decrease in respiratory rate by 2 +/- 5 breaths/min (p less than 0.05) was the only change that occurred in the control group.
  
• Thirteen patients (65%) in the control group and 7 patients (35%) in the CPAP group met our criteria for treatment failure during the study (p = 0.068).

Patients with acute pulmonary edema, characterized by dyspnea, tachypnea, tachycardia, accessory muscle use, bilateral rales, and typical findings of congestion on a chest radiograph to get either:

• n = 13 to receive nasal CPAP (10 cm H2O)
• n = 14 to receive nasal BiPAP (inspiratory and expiratory positive airway pressures of 15 and 5 cm H2O)

• After 30 mins, significant reductions in RR (32 +/- 4 to 26 +/- 5 breaths/min), heart rate (110 +/- 21 to 97 +/- 20 beats/min), BP (mean 117 +/- 28 to 92 +/- 18 mm Hg), and Paco2 (56 +/- 15 to 43 +/- 9 torr [7.5 +/- 2 to 5.7 +/- 1.2 kPa]) were observed in the BiPAP group, as were significant improvements in arterial pH and dyspnea scores (p < .05 for all of these parameters).
  
• Only breathing frequency improved significantly in the CPAP group (32 +/- 4 to 28 +/- 5 breaths/min, p < .05).
  
• At 30 mins; the BiPAP group had greater reductions in Paco2 (p = .057), systolic BP (p = .005), and MAP (p = .03) than the CPAP group.
  
• The myocardial infarction rate was higher in the BiPAP group (71%) compared with both the CPAP group (31%) and historically matched controls (38%) (p = .05).
  
• Duration of ventilator use, intensive care unit and hospital stays, and intubation and mortality rates were similar between the two groups.

To determine the effectiveness and safety of NPPV in the treatment of adult patients with acute cardiogenic pulmonary edema

Blinded or unblinded randomised or quasi-randomised clinical trials, reporting on adult patients with acute or acute-on-chronic cardiogenic pulmonary oedema and where NPPV (CPAP or bilevel NPPV) plus standard medical care was compared with standard medical care alone.

• Compared with standard medical care, NPPV significantly reduced hospital mortality (RR 0.66, 95% CI 0.48 to 0.89) and endotracheal intubation (RR 0.52, 95% CI 0.36 to 0.75).
  
• No difference in hospital length of stay with NPPV; however, ICU stay was reduced by 1 day (WMD -0.89 days, 95% CI -1.33 to -0.45).
  
• Compared with standard medical care, no observed significant increases in the incidence of AMI with NPPV during its application (RR 1.24, 95% CI 0.79 to 1.95) or after (RR 0.70, 95% CI 0.11 to 4.26).
  
• Fewer adverse events with NPPV use (in particular progressive respiratory distress and neurological failure (coma)) when compared with standard medical care.

NPPV in addition to standard medical care is an effective and safe intervention for the treatment of adult patients with acute cardiogenic pulmonary edema. The evidence to date on the potential benefit of NPPV in reducing mortality is based on small-trials and further large-scale trials are needed.