Key Clinical Questions
What risk factors predict postoperative pulmonary complications?
What role does diagnostic testing play in the evaluation of perioperative pulmonary risk?
What objective tools are available for performing a preoperative pulmonary risk assessment?
What strategies are effective to reduce and manage postoperative pulmonary risk?
A comprehensive preoperative evaluation must include assessment of the risk of postoperative pulmonary complications. While few would argue this point, pulmonary risk is often underappreciated as clinicians typically focus the majority of their energy on the preoperative cardiac evaluation and preventing venous thromboembolic complications. Highlighting the risk of this approach, postoperative respiratory problems occur with similar frequency and greater morbidity than cardiovascular complications.
Pulmonary complications following anesthesia and surgery result from central nervous system suppression and altered respiratory dynamics. Administration of sedating agents and neuromuscular blockade exposes the patient to the risk of aspiration. Furthermore, regardless of the type of anesthetic technique utilized, patients will experience a reduction in lung volumes perioperatively. Reduction in lung volumes is the primary mechanism that may lead to atelectasis and predispose a patient to the additional complications of pneumonia and respiratory failure. This reduction in lung volumes is greatest for patients undergoing thoracic and upper abdominal surgery. Table 51-1 lists specific postoperative pulmonary complications and diagnostic considerations for each.
TABLE 51-1Common Postoperative Pulmonary Complications ||Download (.pdf) TABLE 51-1 Common Postoperative Pulmonary Complications
|Condition ||Diagnostic Considerations |
|Atelectasis || |
|Pneumonia || |
Diagnostic criteria vary—utilize same as nosocomial pneumonia
Often polymicrobial—common pathogens include Pseudomonas, Staphylococcus aureus, Streptococcus pneumoniae and enteric Gram-negative bacilli
Though aspiration of secretions is a likely contributor to development, anaerobic bacteria rarely cause postoperative pneumonia
|Respiratory failure || |
Inability to wean off ventilator support within 48 h of surgery or unplanned reintubation
Typically, a combination of hypoxic and hypercapnic respiratory failure
|COPD exacerbation || |
Clinicians intuitively recognize several risk factors for pulmonary complications, but some predictors of postoperative respiratory problems are not obvious. Additionally, clinicians may struggle with the appropriate utilization of preoperative pulmonary diagnostic testing. Recently published risk indices and practice guidelines provide valuable assistance in the identification of risk factors and the performance of evidence-based preoperative evaluation.
PATIENT-SPECIFIC RISK FACTORS
Several different patient characteristics increase postoperative pulmonary risk (Table 51-2). While most of these patient-specific factors are nonmodifiable, their identification is important for providing patients, surgeons and anesthesiologists with an accurate assessment of perioperative risk and to identify patients for whom one should employ risk reduction strategies.
TABLE 51-2Patient-Specific Risk Factors for Postoperative Pulmonary Complications