A 76-year-old man comes for outpatient follow-up after recent coronary artery bypass grafting surgery. He has abundant, yellowish wound discharge from the lower part of the surgical midsternal wound. The patient has no chest pain, dyspnea, fevers, or abdominal swelling. He underwent uncomplicated coronary artery bypass grafting surgery for severe coronary artery disease 9 days ago, which included internal thoracic artery harvesting. Medical history also includes hypertension and type 2 diabetes mellitus. The patient is afebrile, and vital signs are within normal limits. On examination, the sternum appears stable to palpation. There is swelling and soft tissue separation at the lower part of the wound with copious discharge. Which of the following is the next best step in managing this patient?
This patient, who recently underwent coronary artery bypass grafting (CABG), has evidence of separation of the sternal wound (dehiscence). Wound dehiscence after CABG is a relatively common complication, and management is determined by the extent of tissue involvement.
Soft tissue dehiscence occurs when only the superficial tissues (eg, skin, muscle) separate. There are no signs of sternal instability or systemic illness; local wound care or debridement followed by primary closure is indicated.
Sternal dehiscence occurs with separation of the edges of the approximated sternum and may occur with or without soft tissue dehiscence. Sternal instability and nonunion is characterized by "clicking" or "rocking" on sternal palpation. It is a surgical emergency and requires sternal rewiring to prevent cardiac trauma.
A high-mortality complication of dehiscence is deep tissue infection (mediastinitis), due to either contiguous spread of superficial infection or intraoperative deep tissue contamination. Although it classically presents with systemic symptoms (eg, fever, tachycardia), chest pain, chest wall edema/crepitus, and purulent wound discharge, atypical presentations can occur; therefore, any patient with significant sternal wound drainage should be evaluated with chest and sternal imaging (eg, mediastinal fluid collections or pneumomediastinum on CT scan). Management includes emergency surgical debridement, tissue cultures, and empiric intravenous antibiotics.
(Choice B) Patients with uncontrolled diabetes are more likely to develop postoperative wound complications; however, given the copious wound drainage, further investigation is warranted to exclude deep infection.
(Choices C and D) Topical and oral antibiotics do not have a role in the initial management of postoperative wound infection due to the risks of underlying deep tissue infection. Broad-spectrum intravenous antibiotics should be initiated if mediastinitis is suspected, but in this hemodynamically stable patient with no signs of sternal instability, imaging and cultures should be pursued first to confirm the diagnosis and guide management.
(Choice E) Wound cultures should be obtained to guide antibiotic therapy. However, observation without imaging would be inappropriate given the risk of substantial morbidity and mortality associated with mediastinitis.
Educational objective:
Mediastinitis is a complication of cardiovascular surgery characterized by infection of the deep tissues; it classically presents with systemic symptoms (eg, fever, tachycardia), chest pain, chest wall edema/crepitus, and purulent discharge; but it can also present atypically. Therefore, any patient with copious drainage from the sternal wound should undergo chest imaging. Radiographic findings include fluid collections or pneumomediastinum.