Non-invasive Ventilation Versus Continuous Positive Airway Pressure in Cardiogenic Pulmonary Edema

Continuous Positive Airway Pressure (CPAP) and Non-Invasive Ventilation (NIV), has played a decisive role in the treatment of Acute Respiratory Failure (ARF) secondary to Cardiogenic Pulmonary Edema (CPE). The use of either CPAP or NIV has resulted in greater clinical improvements than the ones that have been previously obtained by using a standard medical therapy. Although there is a strong indication for NIV in hypercapnic patients, the situation whether NIV is superior to CPAP remains unclear, and hence, both have been recommended.

NIV and CPAP have both been successfully used in patients admitted to an Intensive Care Unit (ICU) suffering from CPE. However, few trials have been published on the ICU scenario. In addition, Acute Coronary Syndrome (ACS) has been considered to be an exclusion criterion in several trials.

At the time of the onset of CPE, either in the Emergency Department (ED) or in the ward, all participants received a standard medical therapy (oxygen through a Venturi mask, morphine, intravenous nitroglycerin if their systolic blood pressure >160 mmHg, together with loop diuretics), all at the discretion of the attending physician. In the absence of a clinical improvement [dyspnea, respiratory rate >25rpm, transcutaneous arterial oxygen saturation (SaO2) <90%], the participant was admitted to the ICU and assigned to the NIV group or the CPAP group, regardless of the treatment that they had received in the ED. The participants that were admitted to the ICU at the onset of CPE were randomised without a trial of medical treatment. The assignment of each group was performed by opening a sealed envelope following a prior randomisation by using a computerised system.

Statistical. A comparative analysis was conducted by using the Student's t-test or the Mann-Whitney test for a comparison of the quantitative variables for the parametric and non-parametric characteristics, respectively. For the qualitative variables, the investigators used the Chi-Square statistic or Fisher's exact test. A statistical significance was reached if P<0.05. The cumulative probability of survival was compared by using a Kaplan-Meier estimation of survival and a Log-Rank Test to compare both of the groups.

Inclusion criteria

• Participants suffering from CPE, defined as having the presence of dyspnea, respiratory rate >25 breaths/minute, the use of accessory respiratory muscles, cyanosis, cold sweats, bilateral crackles and/or wheezing on pulmonary auscultation, hypoxaemia, hypertension, and a predominance of bilateral pulmonary infiltrates upon a chest radiography (if available).
• The potential causes of CPE have been understood to be Acute Coronary Syndrome (ACS) with or without a persistent ST-segment elevation, hypertensive emergency, valvulopathy, acute arrhythmia, endocarditis, or decompensation due to a chronic heart failure.

Exclusion criteria

• The exclusion criteria were: a refused consent, the patient's inability to cooperate, severe encephalopathy (Glasgow Coma Score <10)
• Anatomical difficulty when adjusting the face mask, non-cardiogenic Acute Respiratory Failure (pneumonia, blunt chest trauma, or chronic obstructive pulmonary disease)
• Respiratory or cardiac arrest on admission, together with the need for an immediate intubation.
• Specific cardiac contraindications were also considered, including: cardiogenic shock on admission established by systolic blood pressure (SBP) <90 mmHg, or a dependence on vasoactive drugs (norepinephrine >0.5 µg/kg/min).