An Attorney's Guide to Postoperative Pneumonia

Pneumonia is an acute infection of the lungs. Postoperative pneumonia can be defined as either hospital-acquired pneumonia (HAP, pneumonia developing 48-72 hours after hospital admission) or ventilator-associated pneumonia (VAP, pneumonia developing 48-72 hours after endotracheal intubation) occurring in the post-surgical patient.

Reports from the National Healthcare Safety Network (NHSN) in the United States have documented a recent decline in VAP rates related to implementing prevention strategies. However, the highest rates of VAP remain in surgical ICUs.

• Postoperative pneumonia has been shown to be a common complication for general surgical procedures, with incidences ranging from 0.5% to 28%¹
• The most common serious complication after emergency abdominal surgery is a postoperative pulmonary complication with an incidence rate of 20–50%^2-4
• The rate of postoperative pneumonia in emergency surgery patients was 2.4 times greater than that in non–emergency surgery patients.⁵

Individuals of a certain age or having certain medical conditions face a higher risk of developing pneumonia.

Patient-related Risk Factors:

• Older age
• Poor nutrition status
• Preoperative weight loss
• Pre-existing dysphagia
• Swallowing difficulties from neurocognitive or neuromuscular disease
• Pre-existing comorbidities
• Immunosuppression (e.g., diabetes mellitus, chronic alcohol abuse)
• Pulmonary dysfunction with low pre-existing oxygen saturation (related to COPD)
• Pre-existing pneumonia
• Respiratory muscle wasting
• Smoking history
• Functional status (independent preoperative predictor variable)
• Evidence of bilateral aspiration pneumonia⁶

Postoperative Factors:

• Bed rest for more than three days after surgery
• Mechanical ventilation for more than 24 hours
• Nasogastric tube use
• Blood transfusion

Although the diagnosis of pneumonia is based on clinical, microbiological, and radiological criteria in the postoperative period, some classical criteria for pneumonia, such as fever, leukocytosis, and worsening gas exchange, are often present without pneumonia. So, the diagnosis of pneumonia is difficult because the clinical findings are nonspecific.

Also, lung infection can arise from various pathogens with varying clinical and biological markers and imaging manifestations. This is particularly so for postoperative pneumonia with both underdiagnosis and overdiagnosis, depending on diagnostic criteria.

Postoperative pneumonia will be diagnosed when the patient meets both clinical and bacteriological strategies.

Clinical Approach

• The clinical approach means a new or progressive radiographic infiltrate plus at least two of three clinical features (fever greater than 38 °C, leukocytosis or leukopenia, and purulent secretions).

Bacteriological Strategy

• The bacteriological strategy is as follows: Sputum culture was performed at least twice with a fiberoptic bronchoscope or alveolar lavage fluid. Pathogenic bacteria were detected in the sputum culture, and the first positive result appeared within 48 hours after surgery.⁷

Additional Methods

Blood tests for white blood cells (WBC), procalcitonin (PCT), and C-reactive protein (CRP) have been widely done to detect postoperative pneumonia, but their effectiveness is still controversial.⁸

Chest x-rays or chest computed tomography and clinical criteria are of limited accuracy in diagnosing postoperative pneumonia.

CRP is sensitive but not very specific, being increased in all inflammatory disorders. Despite its limitations, PCT differentiates better between infectious and noninfectious causes of critical illness than CRP.⁹

The absolute value of interleukin-6 in the blood is more sensitive in the diagnosis of early postoperative pneumonia than that of PCT and CRP, WBC.

Lactate levels measured at 12 hours after the operation had the highest predictive ability for diagnosis of overall postoperative complications, including postoperative pneumonia and postoperative in-hospital mortality.¹⁰

The initiation of early appropriate empiric antibiotics to treat HAP or VAP significantly improves patient survival.¹¹ To better understand the antibiotic choice, examining the microbiology of VAP is essential

Rapid initiation of appropriate antibiotic therapy has a significant effect on the outcome. Several trials have shown increased mortality in patients who have inappropriate antibiotic therapy. Inadequate antibiotic therapy is a strong predictor of death in patients with postoperative pneumonia, irrespective of the underlying disease state and severity of illness.^12,13 Poor risk factor assessment is one of the main reasons for inadequate antibiotic selection.¹⁴

Antibiotic treatment for postoperative pneumonia lasts 7 to 10 days for sensitive pathogens and 14 to 21 days for resistant organisms.

HAP Prevention

Some institutions have initiated aggressive HAP prevention efforts in surgical patients to reduce postoperative pneumonia. The program consisted of the education of physicians and staff and a standardized postoperative electronic order set consisting of chlorhexidine oral hygiene, early ambulation, and head-of-bed elevation.¹⁵

VAP Prevention

The foremost strategy for VAP prevention is to reduce the duration of mechanical ventilation.¹⁶

The development of VAP is related to:

• bacterial colonization of the aerodigestive tract
• aspiration of contaminated secretions into the lower airway

The strategies to prevent infection are therefore:

• reducing bacterial colonization
• decreasing the incidence of aspiration