Cardiac influence on mechanical ventilation time and mortality in exacerbated chronic respiratory failure patients. The role of echocardiographic parameters.

OBJECTIVE

To study the influence of cardiac status on the length of mechanical ventilation, outcome and disease severity in patients admitted to an Intensive Care Unit (ICU) with exacerbation of chronic respiratory failure.

DESIGN AND

SETTING

A 30-month prospective study in a 14 bed ICU PATIENTS AND

METHODS

Fifty nine patients were enrolled, with a mean age 74.7 +/- 9.7 years, mean length of ventilator support 10.8 +/- 12.6 days, and mean APACHE II score 23 +/- 8.3. Within the first 24 hours of admittance, cardiac chamber dimensions, inferior vena cava (IVC), and mitral transvalvular Doppler were evaluated using transthoracic echocardiography; the cardiac rhythm was recorded (presence of sinus rhythm or atrial fibrillation). Blood gases were evaluated at discharge.

RESULTS

Greater length of ventilation was observed in patients presenting atrial fibrillation (p=0.027), particularly when a dilated IVC was also present (>20mm, p=0.004). A high level of serum bicarbonate (>35 mEq/l), was also related with longer ventilation (p=0. 04). Twelve patients died. Mortality was related to the presence of a dilated right ventricle (p=0. 03) and a ratio between right and left ventricle> 0. 6 (p=0.04).

CONCLUSION

Patients submitted to mechanical ventilation due to exacerbation of chronic respiratory failure which present atrial fibrillation require a longer ventilation period, particularly if a dilated IVC is also present. Patients with dilated right cardiac chambers are at an increased risk of a fatal outcome.