One of the major fears in the management of COPD is the potential need of admission to the Intensive Care Unit. The reason is the difficulty in weaning from ventilatory support that very severe patients may develop during the ICU stay. Ventilatory support at the ICU sometimes is very particular in these patients. They may have already adjusted their body to chemical changes in terms of arterial gases.
Acute exacerbation of COPD in ICU
Predicting which patients may require ICU seriously is a challenge. In an issue ofChest(Chest 2008;133:1088-1094) a team from the Department of Internal Medicine and Clinic for Pneumology and Respiratory Cell Research at the University Hospital Basel, Switzerland tested the hypothesis about a marker of cardiac stress as predictor of ICU admission requirement due to acute exacerbation of COPD (AECOPD).
BNP in the heart of COPD
The marker was the B-type natriuretic peptide or BNP which is mainly released from the heart to control different functions related to the adjustment of the body to a damaged heart.
In AECOPD is expected the sudden reduction in the oxygenation due to abrupt insults to the lung. The decreased oxygen (hypoxemia) leads to a heart response to try to support the rest of the organs. According tho D. Stolz and colleagues, the hypoxemic constriction of the vascular pulmonary bed could be paramount in the increased cardiac work. Then, the release of BNP from the heart may be an indicator of potential bigger deterioration of patients with AECOPD.
In their single centered trial of 208 patients wit an AECOPD presenting to the ER, they found that levels of BNP were significantly elevated when compared to the recovery phase of the episode.
A research found…
A total of 9% of patients with AECOPD required ICU treatment to receive mechanical ventilation and cardiovascular intensive management. These group of patients had higher values of BNP.
One of the most interesting findings was that lung function (measured through FEV1) was not correlated with BNP levels. This fact points to a more complex reality of staging systems of COPD. Maybe having a less severe disease does not exclude the possibility of being admitted to ICU, but the general status of the patient (including the cardiac state).
Taking the heart in mind
Although cardiovascular events seem not to be the predominant dangerous factors in AECOPD with fatal results, they need to be under the scope when considering the severity of AECOPD. The cardiac status may define the need of ICU in most COPD patients with exacerbations. One point is clear: exacerbations are more frequent in advanced stages of the disease when the cardiac health may have been injured especially when diagnosis is made late.