Covariates associated with pulmonary complications including unplanned intubation after total knee arthroplasty

Total knee arthroplasty (TKA) is widely regarded as a safe procedure. Yet pulmonary complications do occur sometimes, requiring unplanned intubation, creating difficulties with ventilator weaning, or resulting in pneumonia. Our goal was to identify which risk factors are most strongly associated with these respiratory complications after TKA using the American College of Surgeons National Surgical Quality Improvement Program database (NSQIP) database.

The NSQIP database is a comprehensive de-identified registry of surgical outcomes. Our analytical approach proceeded in two phases. Initially, we conducted univariate analyses to screen individual factors for associations with our three primary outcomes: unplanned intubation, failure to wean from mechanical ventilation, and the development of pneumonia.Factors showing statistical significance in this preliminary screening then advanced to multivariate logistic regression modelling. Variables included patient demographics, such as age and sex, relevant comorbidities (such as diabetes, chronic obstructive pulmonary disease (COPD), and congestive heart failure (CHF), functional status, key laboratory parameters (such as white blood cell (WBC) and platelet counts), American Society of Anesthesiologists (ASA) classification, and anesthesia approach. Statistical significance was defined as p < 0.05.

The strongest predictors across the three outcomes of unplanned intubation, failure to wean, and pneumonia, in descending order, were age, ASA classification, history of COPD, and history of CHF.

Our study found that the risk of pulmonary complications within 30 days following total knee arthroplasty was independently associated with older age, higher ASA class, and history COPD or CHF, increased operative time, and elevated preoperative WBC count.