Cardiogenic Pulmonary Oedema. Management.

Author: Victoria L Henson / Editor: Jason M Kendall / Reviewer: Louise Burrows / Code: CAP6, CAP7, HAP8 / Published: 09/11/2017 Review Date: 09/11/2020

The priorities are to relieve symptoms and to restore haemodynamic stability and tissue perfusion. The approach to management is summarised in Box 5.

Box 5: Emergency Management of CPO:

Airway	Positioning
Breathing	High flow O2 CPAP/BiPAP
Circulation	Nitrates Furosemide
Disability	Morphine
Exposure	Positioning

(a) Airway

Allow the patient to find the best position for their airway and breathing. If the airway is compromised intervene as required. This may be due to (i) a reduction in conscious level due to hypoxia, hypercapnoea or excessive opiate administration, or (ii) due to pulmonary oedema fluid exuding from the lungs.

(b) Breathing

(i) Oxygen

• High flow O2: 15L/minute with a reservoir bag is required for most patients (unless known to retain CO2), as hypoxia is frequently the key problem.
• British Thoracic Society Guidelines suggest supplemental O2 is required only if saturations are < 95% and the patient is short of breath(2).
• Patients with coexistent COPD need careful monitoring. When feasible the inspired O2 can be reduced to achieve saturations of 90-92%.
• Once non-invasive ventilation (NIV) is initiated O2 supplementation will still be required.

(ii) Non-invasive Ventilation (NIV)

The aim of NIV is to improve oxygenation, decrease the work of breathing and increase cardiac output. Continuous Positive Airways Pressure (CPAP) provides a constant level of positive airways pressure preventing alveolar collapse. Bi-level Positive Airways Pressure (BiPAP) enables increased CO2 clearance by providing a higher level of positive pressure on inspiration.

Box 6: Evidence Base for Non-invasive ventilation in CPO

A Cochrane Review (2008) systematically reviewed the research data published prior to 2005 and concluded that NIV should be considered and implemented in all CPO patients early unless contraindicated. The Review reported that: (i) CPAP decreased intubations, mortality and length of ITU stay and that (ii) BiPAP may be of use in CO2-retaining patients but that more research was required. In order to avoid 1 death, the number needed to treat (NNT) with CPAP was 9 and to avoid 1 intubation the NNT with CPAP was 6(3).

The 3CPO trial also published in 2008 is the largest multicentre RCT which compared standard medical therapy to BiPAP and CPAP(4). This study found no reduction in mortality or intubation rates in either of the NIV groups but patients felt better more quickly. There was no evidence of additional harm.

The ESC recommends that all CPO patients should be considered for NIV early on in their management (unless contraindicated)(1).

Learning Bite

Consider NIV early in the management of all patients with cardiogenic pulmonary oedema, unless contraindicated

Table 3: Practical aspects related to Non-invasive Ventilation in CPO

Indications	Consider in all patients with CPO Particularly pH<7 .35="" li=""> Respiratory rate >20/min
Cautions	Right ventricular failure Cardiogenic shock Severe obstructive airways disease Agitated patient
Contraindications	Immediate endotracheal intubation indicated Respiratory arrest or inadequate spontaneous ventilation Worsening life threatening hypoxia Unconscious patient unable to protect own airway
How to deliver NIV	Correctly fitting mask Supplemental O2 Commence PEEP at 5-7.5 cm H2O and increase to 10cm as tolerated Continue for 30min/hr until reduction in dyspnoea and saturations are maintained off NIV
Complications	Intolerance due to anxiety, skin/eye discomfort, dry mouth Worsening right ventricular failure Hypercapnoea Pneumothorax Aspiration

(c) Circulation

(i) Diuretics:

Loop diuretics reduce preload by preventing sodium chloride reabsorption in the ascending Loop of Henle, which increases fluid excretion. Preload is also reduced by their vasodilatory action. Both of these actions should be beneficial in a patient with CPO and fluid overload.

For decades diuretics have been the accepted mainstay of treatment in CPO despite a lack of randomised controlled trials demonstrating beneficial outcome; there is some evidence suggesting a detrimental effect at high doses(1,5,6,7,8). Specifically, their use may dehydrate the euvolaemic patient and cause hyponatraemia and hypotension. Also, due to their effect on the renin/angiontensin/aldosterone system and stimulation of the sympathetic system, diuretics may increase afterload thereby decreasing stroke volume and cardiac output.

Patients with CPO generally have elevated systemic vascular resistance and reduced renal perfusion and consequently diuretic action may be delayed by up to 1 hour. It is probably only the vasodilatory action of diuretics that is initially beneficial and this can also be achieved with IV nitrates(5).

The ESC Guidelines advocate small intravenous boluses of furosemide at 20-40mg for patients with CPO and symptoms of fluid overload or congestion. It advocates high dose diuretic use only for those patients with clinical evidence of fluid overload and a history of chronic oral diuretic use(1)

Learning Bite

High dose diuretics should be used with caution and only in those with evidence of fluid overload and a history of long term diuretic use

ii) Vasodilators:

These agents have positive physiological effects by off-loading the heart through their venous and/or arteriolar vasodilatory effects causing a reduction in pre-load and/or after-load. Vasodilators should not be used in patients with a systolic blood pressure of less than 90mmHg or in those with aortic stenosis (who are dependent on sufficient preload to force blood across the gradient).

Nitrates

The majority of patients with CPO have a high-end-of-normal blood pressure at presentation and are able to tolerate nitrates.
Initially administer sublingual nitrates until intravenous access is established and then commence at a rate of 10-20mcg/min increasing every 3-5min by 5-10 mcg/min as needed and as BP allows.(1)

Nitroprusside

This is an alternative vasodilator which reduces preload and afterload. It is particularly useful in the rare cases of extreme hypertension precipitating CPO (ie. in a hypertensive emergency).
It can precipitously drop the systolic blood pressure but tolerance is not an issue as it is with nitrates.
The ESC 2008 Guidelines suggest cautiously commencing an infusion at 0.3 mcg/Kg/min (titrated up to 5 mcg/Kg/min) with invasive blood pressure monitoring (1).

Nesiritide

This is a recombinant B-type natriuretic peptide with both a diuretic and natriuretic effect, as well as being a venous and arterial vasodilator.
It is currently used in the USA but has limited licensing in the UK and Europe.(1)

(iii) Inotropes:

Inotropes should be considered if hypotension or signs of end organ hypoperfusion persist despite use of vasodilators/diuretics. They should be commenced early once the need is recognised and stopped as soon as adequate tissue perfusion is achieved. Their use is associated with increased mortality, as they increase cardiac oxygen demand and myocardial injury.

Dobutamine is probably the first choice agent. Infusion is commenced at 2-3mcg/kg/min and increased as required.(1)

(d) Disability

Morphine should be given early for patients who are agitated and distressed or complaining of chest pain. Opiates also provide a potential physiological benefit due to their vasodilatory effects and resultant reduction in pre-load. Only small boluses of 2.5-5mg are recommended as opiates may cause hypotension and/or respiratory depression.