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Three Part Question

[In patients with acute LVF] is [CPAP better than O2 via normal mask] at [avoiding intubation and improving mortality]?

Clinical Scenario

A 76 year old male is brought in to A&E in a collapsed state. He has a history of ischaemic heart disease. He is agitated, tachypnoeic and sweating profusely. His neck veins are distended and there are widespread coarse crepitations in his chest. He has a diminished oxygen saturation. You make a clinical diagnosis of acute cardiogenic pulmonary oedema. In addition to vasodilator treatment and opiates, you wonder whether you should administer non-invasive continuous positive airways pressure (CPAP).

Search Strategy

Medline 1966-09/00 using the OVID interface.
([exp pulmonary edema OR pulmonary oedema.mp OR exp ventricular dysfunction, left OR exp heart failure, congestive OR exp myocardial infarction OR left ventricular failure.mp OR LVF.mp) AND (exp positive-pressure respiration OR CPAP.mp OR continuous positive airway pressure$.mp OR PEEP.mp OR positive end expiratory pressure$.mp] AND maximally sensitive randomised controlled trial filter) LIMIT to human and english language

Search Outcome

114 papers were found of which 109 were either irrelevant or of insufficient quality for inclusion. The remaining 5 papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Rasanen J et al, 1985, Finland	40 patients with acute cardiogenic pulmonary oedema. RR > 25 and PaO2 < 200 mm Hg CPAP (20) v control (20)	PRCT	Need for intubation	6/20 v 12/20 (NS)	Small numbers Unblinded
			Hospital mortality	17/20 v 14/20 deaths in hospital (NS)
Bersten A et al, 1991, Australia	39 patients with acute cardiogenic pulmonary oedema. PaO2 <70 mm Hg and PaCO2 >45 mm Hg CPAP (19) v control (20)	PRCT	Need for intubation	0/19 v 7/20 (p<0.005)	Small numbers Unblinded Randomisation not concealed
			Hospital mortality	2/19 v 4/20 (NS)
Lin M and Chiang HT, 1991, Taiwan	55 patients with acute cardiogenic pulmonary oedema. RR>22 CPAP (25) v control (30)	PRCT	Need for intubation	7/25 v 17/30 (p<0.05)
			Hospital mortality	2/25 v 4/30 (NS)
			Shunt size	Significantly improved in CPAP group
			PaO2	Significantly improved in CPAP group
Lin M et al, 1991, Taiwan	100 patients with a clinical diagnosis of acute cardiogenic pulmonary oedema CPAP (50) v control (50)	PRCT	Need for intubation	8/50 v 18/50 (P<0.01)	Unblinded
			Hospital mortality	4/50 v 6/50 (NS)
Takeda S et al, 1998, Japan	22 patients with acute cardiogenic pulmonary oedema. PaO2 <80 mm Hg CPAP (11) v control (11)	PRCT	Need for intubation	2/11 v 8/11 (P=0.03)	Small numbers Unblinded
			hospital mortality	1/11 v 7/11 (P=0.02)

Comment(s)

All of these trials have shown significant reductions in the need to intubate patients in acute pulmonary oedema. In these small trials a reduction in mortality could not be seen. The numbers in the trials are not large and there is not yet absolute evidence of benefit from CPAP. A large, well-designed PRCT may provide this. In the meantime it would appear that patients with severe LVF will benefit from CPAP.

Clinical Bottom Line

Patients presenting with severe acute pulmonary oedema should be treated with continuous positive airway pressure (CPAP).

References

1. Rasanen J, Heikkila J, Downs J,et al. Continuous positive airway pressure by face mask in acute cardiogenic pulmonary edema American Journal of Cardiology 1985;55(4):296-300.
2. Bersten AD, Holt AW, Vedig AE, et al. Treatment of severe cardiogenic pulmonary edema with continuous positive airway pressure delivered by face mask. New England Journal of Medicine 1991;325(26):1825-30.
3. Lin M, Chiang HT. The efficacy of early continuous positive airway pressure therapy in patients with acute cardiogenic pulmonary edema. Journal of the Formosan Medical Association. 1991;90(8):736-43.
4. Lin M, Yang YF, Chiang HT, et al. Reappraisal of continuous positive airway pressure therapy in acute cardiogenic pulmonary edema. Short-term results and long-term follow-up. Chest. 1995;107(5):1379-86.
5. Takeda S, Nejima J, Takano T, et al. Effect of nasal continuous positive airway pressure on pulmonary edema complicating acute myocardial infarction. Japanese Circulation Journal. 1998;62(8):553-8.