INTRODUCTION
Lung dysfunction after cardiac surgery remains an important cause of
postoperative morbidity despite continuing improvement in
cardiopulmonary bypass techniques and postoperative intensive care
management. There is a significant co-existence of cardiac and pulmonary
disease. Moreover, most of the patients who are candidates for cardiac
surgery have pre-existing pulmonary pathology. The important correlation
of lung function and cardiac surgical outcomes is emphasized by the
prognostic value of chronic lung disease assessment in the Society of
Thoracic Surgeons (STS) and EuroSCORE II operative mortality estimation
tools 1. This led some centers to perform pulmonary
function testing (PFT) routinely before any elective cardiac surgery
procedure based on the evidence that spirometry evidence of obstructive
ventilatory pattern may predict the duration of mechanical ventilation
and intensive care unit (ICU) stay following elective cardiac surgery2. Additionally, different levels of chronic
obstructive pulmonary disease (COPD) severity may impact the prediction
of postoperative morbidity and prolonged lengths of ICU and hospital
stay in patients undergoing coronary artery bypass grafting (CABG)3.
However, pulmonary congestion secondary to heart failure or left-sided
heart valve disease is known to cause both obstructive and restrictive
abnormalities in PFT, which obviously could influence the preoperative
spirometry results of cardiac surgical patients. It is debatable whether
abnormal PFT results in those patients represent a real risk of
postoperative pulmonary complications or they are just a reflection of
the left-sided heart congestion. This led some centers to adopt the
selective performance of preoperative spirometry at the discretion of
the individual physician or departmental standards based on patient
history of respiratory symptoms or smoking habits. Some authors did not
even include PFT in their proposed model for predicting patients who
require prolonged ventilation post cardiac surgery 4,
that included parsonnet score, ejection fraction (EF), age, and
emergency re-operation for bleeding or cardiac arrest.
Very few studies have looked at the interaction between left-sided heart
valve dysfunction or ventricular dysfunction and the results of lung
spirometry and suggested that lung function parameters may provide
prognostic information in patients with heart failure and may help to
guide treatment decisions 5.
Hence, our study aimed to focus on this subgroup of cardiac surgery
patients with congestive heart failure caused by left ventricular
dysfunction or left-sided heart valve disease and study the prognostic
value of performing preoperative PFT on their postoperative outcomes.