The Effects of Cardiac Surgery on Early and Late Pulmonary Functions

Background: Impaired pulmonary functions are common in cardiac patients. Early and late effects of cardiac surgery on pulmonary function tests (PFTs) are presented.

Methods: Fifty patients undergoing cardiac surgery (coronary artery bypass grafting [CABG, 74%], valve replacement or valvuloplasty [20%] and combined procedures [6%]) were studied. Anginal and cardiac failure symptoms severity, and smoking history, were evaluated preoperatively. PFTs were studied and compared pre-, and 3 weeks and 3.5 months postoperatively.

Results: Pre- and postoperative PFTs were inversely related to severity of preoperative symptoms. Forced vital capacity (FVC) dropped from 98% of predicted preoperatively, to 63% (P < 0.00001) and 75% (P < 0.00001) 3 weeks and 3.5 months postoperatively, respectively. Expiratory volume in the first 1 s of forced expiration (FEV1.0) decreased from 95% to 61% (P < 0.00001) and 70% (P < 0.00001), respectively. Forced expiratory flow at 50% of vital capacity (FEF50) decreased from 85% to 56% (P < 0.00001) and 59% (P < 0.00001). Forced expiratory flow at 75% of vital capacity (FEF75) decreased from 77% to 47% and 47% (P < 0.00001). Peak expiratory flow rate (PEFR) declined from 101% to 66% (P < 0.00001) and 86% (P < 0.003). Maximal voluntary ventilation declined from 103% to 68% (P < 0.00001) and 77% (P < 0.00001). Only FVC (P < 0.0003), FEV1.0 (P < 0.02) and PEFR (P < 0.0001) partially recovered postoperatively. Smoking history did not affect perioperative PFTs. Pre-, but not postoperative FVC, FEV1.0, FEF50 and FEF75 were worse in valve than in CABG patients.

Conclusions: Pulmonary functions deteriorate significantly for at least 3.5 months after cardiac surgery. Preoperative cardiac ischaemic and failure symptoms are inversely related to perioperative PFTs.