NIPSV for acute cardiogenic pulmonary oedema does not increase the risk of myocardial infarction compared to CPAP

Abstract

Question

Acute cardiogenic pulmonary oedema (ACPO) can be managed with either non-invasive pressure support ventilation (NIPSV) or non-invasive continuous positive airway pressure (CPAP). Does management with NIPSV increase the risk of myocardial infarction compared to management with CPAP?

Design

Randomised controlled trial with concealed allocation.

Setting

High-dependency unit of a hospital emergency department in Turin, Italy.

Patients

52 adults with severe ACPO, defined as acute dyspnoea, > 30 breaths per minute, use of accessory respiratory muscles, oxygen saturation (SpO₂) < 90% with F_iO₂ 60%, and radiological signs of ACPO. Patients with signs of acute coronary syndrome (ACS) on hospital admission were excluded from the study.

Interventions

All patients received standard medications (diuretic, nitroglycerin, morphine) and oxygen. NIPSV was applied by a Pulmonetics Systems LTV 1000 ventilator. CPAP was administered by means of a flow generator (Whisper-Flow) with an expiratory (PEEP) valve. Patients randomised to NIPSV (n = 25) received sufficient inspiratory pressure (IPAP) to generate a tidal volume of ∼7 mL/kg, and oxygen to maintain SpO₂ at ∼93%, via an oronasal mask. Expiratory pressure (EPAP) was gradually increased until SpO₂ ≥ 96% (maximum of 12 cmH₂O). Those randomised to CPAP (n = 27) commenced at 5 cmH₂O via an oronasal mask with oxygen to maintain SpO₂ at ∼93%. The CPAP was gradually increased until SpO₂ ≥ 96% (maximum of 12 cmH₂O). Treatment failure was defined as cardiac arrest, respiratory distress and arterial blood gas deterioration for > 60 min, PaO₂/F_iO₂ < 100 mmHg, coma or psychomotor agitation, haemodynamic instability, or life-threatening arrhythmias. Otherwise, treatment continued until the participant met objective criteria of recovery.

Outcomes

The primary outcome was the rate of acute myocardial infarction (AMI). Secondary outcomes included rate of endotracheal intubation, death, duration of ventilatory assistance, and lengths of stay in the hospital and high-dependency unit.

Results

In the NIPSV group, the average EPAP and IPAP applied were 7 ± 1 and 15 ± 3 cm H₂O, respectively. In the CPAP group, the mean pressure applied was 9 ± 2 cm H₂O. AMI occurred in four patients on NIPSV and eight patients on CPAP, which was not significantly different, absolute risk reduction (ARR) 0.14, 95% CI –0.10 to 0.34. Also not significantly different were the number of intubations with only one in the NIPSV group, ARR –0.04, 95% CI –0.20 to 0.09, and the number of deaths with three in the NIPSV group and two in the CPAP group, ARR –0.05, 95% CI –0.23 to 0.13. The lengths of stay in hospital and in the high-dependency unit also did not significantly differ between the groups.

Conclusion

This study demonstrated no significant difference in AMI among patients with ACPO managed with NIPSV versus CPAP.