Cor pulmonale.

Clinical recognition and prognosis

‘Nobody ever died of peripheral oedema. It took a while for it to accumulate, and it takes a while for it to disappear. Do not try to make it go away too fast.[1]’

Cor pulmonale usually reflects late and irreversible lung damage, and as such the salt and water retention that occurs is secondary – reversing this doesn’t cure the patient. The aim of therapy should be to remove oedema causing discomfort, but not diurese the patient to dryness. It has been suggested that the changes in renal haemodynamics[2] associated with hypercarbia are as important a cause of fluid retention as is the conventional mechanism of pulmonary hypertension and right-sided myocardial ‘failure’. Also, recall that a degree of ‘left’ sided failure may be seen in severe cor pulmonale, possibly based on diastolic ventricular interaction[3].

Management of cor pulmonale.

• Stop non-steroidals anti-inflammatory drugs.
• Restrict sodium intake to at most 2g/d, i.e. no salt on the table, add no salt when cooking, and avoid salty foods – crisps, most ‘manufactured’ foods.
• Avoid unnecessary intravenous infusions, and if a drip is essential for another reason, use 5% DW rather than saline.
• Start furosemide in a dose appropriate to renal function rather than degree of oedema. For instance, 80 mg/day with normal renal function is quite adequate. The main way of determining dose is by response, and doses as high as 250 or 500 mg per day may be needed, but do not start with these doses.
• Avoid digoxin.
• Low flow oxygen will help reduce pulmonary hypertension in the acute phase, but be careful in the situation of loss of hypercarbic drive (if in doubt, monitor blood gases – a rise in PaCO₂ of more than 1.5 kPa  with 20 to 30 minutes should prompt extreme caution).
• Venesection may help to reduce viscosity if the haematocrit is more than 55 although there is no clear evidence of survival benefit.
• Don’t forget to treat associated chest infections (e.g. with oral amoxicillin).
• Be wary of precipitating dangerous hypokalaemia with combinations of theophylline, salbutamol and furosemide – check the [K⁺] if in doubt.
• The use of steroids is dictated by the amount of bronchospasm – if you think the patient will benefit, use prednisone in lowish doses (e.g. 15 mg/day) but remember that sodium retention is a side effect.

[1] Franklin C. 100 thoughts for the critical care practitioner in the new millenium. Crit Care Med. 2000;28:3050-52.

[2] Baudouin SV. Oedema and cor pulmonale revisited. Editorial. Thorax 1997;52:401-2. 

[3] De Bono D. Diastolic ventricular interaction: Starling (and Bernheim) revisited. Lancet. 1997;349:1712.