BACKGROUND: Patients receiving an elective total knee replacement (TKR) are frequently older and immobilized. The related decline in respiratory function and structural changes may place these patients at an increased risk of perioperative pulmonary complications.

METHODS: This study reviewed the data of 239 consecutive procedures performed by a single surgeon. The data examined included the patient's characteristics (age, gender, height, weight and body mass index [BMI]); concurrent pulmonary comorbidity (presence vs. absence); anesthetic techniques (general vs. spinal); types of operation (unilateral vs. bilateral); duration of operation (< 4 vs. ≥ 4 hr); duration of tourniquet inflation (< 2 vs. ≥ 2 hr); number of perioperative transfusions (≤ 4 vs. ≥ 5 units); and American society of anesthesiologists (ASA) physical status. Pulmonary complications were grouped together as a single outcome. A Chi-square test and multiple logistic regression analysis were used to identify the risk factors. A P value < 0.05 was considered significant.

RESULTS: Pneumonia, pulmonary edema, pulmonary congestion, atelectasis and pulmonary embolism were the pulmonary complications (n = 28; 11.7%) examined. Age, gender, BMI, pulmonary comorbidity, type and duration of surgery, duration of tourniquet inflation, anesthetic technique and ASA physical status were not associated with pulmonary complications. Only the number of packed cells transfused (≥ 5 units) was found to be associated with the pulmonary complications (odds ratio 5.21; P = 0.015). In particular, transfusions were related to pneumonia, pulmonary edema, pulmonary congestion and pulmonary embolism (P < 0.01). However, atelectasis was not related to any of the potential risk factors including the anesthetic technique.

CONCLUSIONS: Transfusion requirements may be an important risk factor of the early postoperative pulmonary complications in patients receiving a TKR.