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

Non-Invasive Mechanical Ventilation Versus Continuous Positive Airway Pressure Relating to Cardiogenic Pulmonary Edema in an Intensive Care Unit

The aim of the present study was to demonstrate that an Non-Invasive Ventilation (NIV) performs better than a Continuous Positive Airway Pressure (CPAP) in the management of Cardiogenic Pulmonary Edema (CPE) within an Intensive Care Unit (ICU) setting.

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.

Non-invasive ventilation,, continuous positive airway pressure, cardiogenic pulmonary oedema,, acute respiratory failure

For the NIV group, a BiPAP Vision was used, by setting the Inspiratory Positive Airway Pressure (IPAP) at a level that was required to achieve a tidal volume of approximately 8-10 ml/kg. Also an Expiratory Positive Airway Pressure (EPAP) was set at a minimum of 5 cmH20 during the first hour, gradually increasing until there was a clinical improvement. Fraction inspiratory of oxygen (FiO2) was applied to maintain a transcutaneous arterial oxygen saturation (SaO2) of 92%-94%. NIV was continuously applied until there was a clinical and/or a gasometrical improvement, at which time they were replaced by a Venturi mask with FiO2 of 0.4.

The CPAP was applied by using a flow generator with adjustable fractional inspired oxygen (FiO2). This was connected to the Positive End-Expiratory Pressure (PEEP) valve that was placed in the face mask. In the second instance, the CPAP system that was used was a Boussignac CPAP System Flow Jet. The Boussignac valve takes gas from a single source and splits it in order to create four high flow jets. These jets converge in the chamber creating a virtual valve. A initial level of 5cmH20 of PEEP was recommended for the first hour of ventilation, with subsequent increments (up to 15cmH20) until a clinical improvement was obtained. CPAP was continuously applied until there was a clinical and/or a gasometrical improvement, at which time it was replaced by a Venturi mask.

Need for an Endotracheal Intubation Within Seven Days After Onset of Cardiopulmonary Edema at the Intensive Care Unit

Period of ventilation (either noninvasive ventilation or continouos positive airway pressure) while the patient suffers from acute respiratory failure secondary to cardiopulmonary edema

Time (hours) from start of ventilation until the removal of both devices because of improve or failure

Mortility of patients within of the first 28 days after randomization (either at intensive car unit or at hospital)

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).