A 60-year-old woman undergoes elective coronary artery bypass surgery and aortic valve replacement. The postoperative course is complicated by acute renal failure, atrial fibrillation, and pulmonary edema. On the third postoperative day, the patient cannot tolerate attempted extubation and requires reintubation. On the fifth postoperative day, she develops a fever to 38.9 C (102 F). Her blood pressure is 110/65 mm Hg, pulse is 110-120/min and irregular, and respirations are 32/min. Chest x-ray shows dense infiltrates in the right middle and lower lobes. White blood cell count is 16,200/mm3 with 8% bands. Which of the following is the most appropriate next step in management of this patient?
Show Explanatory Sources
This intubated patient's presentation suggests ventilator-associated pneumonia (VAP). VAP is a type of nosocomial pneumonia that develops ≥48 hours after endotracheal intubation and is most commonly caused by aerobic gram-negative bacilli (eg, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and gram-positive cocci (eg, methicillin-resistant Staphylococcus aureus, Streptococcus). Patients usually have fever, purulent secretions, difficulty with ventilation (eg, increased respiratory rate, decreased tidal volume), and leukocytosis.
The first step is to obtain a chest x-ray. Patients with a normal x-ray are unlikely to have VAP and should be evaluated for other causes. Those with an abnormal x-ray (eg, alveolar infiltrates, air bronchograms, silhouetting of adjacent solid organs) require lower respiratory tract sampling (ie, tracheobronchial aspiration) for Gram stain and culture. Patients should receive empiric antibiotics (usually gram-positive, antipseudomonal, and gram-negative coverage) until culture susceptibility results return as treatment delay can increase mortality. However, respiratory tract sampling should be done prior to starting antibiotics as treatment can decrease the sensitivity of both Gram stain and culture.
(Choice A) C-reactive protein may be elevated in VAP, but it is a nonspecific marker of inflammation and cannot identify the underlying diagnosis.
(Choice B) CT scan of the chest can identify complications (eg, empyema) in patients that do not improve clinically with therapy. When Gram stain and culture are not suggestive of VAP, CT scan can also be considered to evaluate for alternate causes (eg, pulmonary embolism). VAP is much more likely than pulmonary embolism in this patient with fever, leukocytosis, and dense infiltrates on chest x-ray. In addition, routine prophylactic anticoagulation (eg, subcutaneous heparin) is standard of care in patients in the intensive care unit, and it is likely that this patient who underwent aortic valve replacement and has atrial fibrillation is already receiving therapeutic anticoagulation therapy (eg, intravenous heparin). All these factors make pulmonary embolism less likely than VAP.
(Choice C) D-dimer is used as an initial test for deep venous thrombosis and pulmonary embolism. However, it is nonspecific and may be elevated in inflammatory or infectious conditions (eg, VAP). This patient's fever, leukocytosis, and lobar infiltrates are more consistent with VAP.
(Choice E) This patient with fever, leukocytosis, and x-ray abnormalities needs respiratory tract sampling to identify the causative pathogen and empiric antibiotics to prevent death.
Educational objective:
Ventilator-associated pneumonia occurs ≥48 hours after intubation and usually presents with fever, purulent secretions, and abnormal chest x-ray. Patients should have lower respiratory tract sampling (Gram stain and culture) and receive empiric antibiotics.