Herpes simplex virus-1 (HSV-1) is a common virus, most commonly presenting as a mucocutaneous infection, and sporadically it is a common cause of viral encephalitis.1, 2 HSV-1 also is responsible for pneumonia in ill patients with normal and suppressed immune systems.3, 4, 5 The following is a case of HSV-1 pneumonia presenting as unexplained failure to wean from a respirator.
Illustrative case
The patient was a 67-year-old woman with a medical history of diabetes mellitus, hypertension, myocardial infarction, resolved MALT lymphoma, who had fatigue and dyspnea on exertion, of recent onset. The patient had normal vital signs and was in no apparent distress. Chest radiograph showed no infiltrates. Spiral computed tomography scan showed a new small lung mass in the right upper lobe and mild pulmonary edema. The patient was pancytopenic; white blood cell count was 1.8 k/mm3 and platelet count was 55 k/mm3. The patient was given trimethoprim-sulfamethaxole and prednisone for Pneumocystis carinii pneumonia prophylaxis; transfused platelets and packed red blood cells were given. The patient refused bronchoscopy for additional evaluation of her lung mass. On hospital day 3, the patient had abdominal pain. A surgical evaluation on hospital day 5 revealed a strangulated umbilical hernia. The surgery was uncomplicated, and the patient was alert and comfortable afterward. She received additional transfusions of red blood cells and platelets. Attempts to wean her from the respirator began one day after surgery.
All weaning attempts failed for the next week, although she remained alert and afebrile. Beause she did not have pre-existing lung disease, her white blood cell count remained between 2.6 and 6.2 k/mm3. During this time, she was mildly hypoxic. On hospital day 12, the patient underwent bronchoscopy to determine the cause of her new lung mass. Cytology of bronchoscopic obtained fluid for bronchoalveolar lavage revealed HSV-1. These results were reported on hospital day 15, and 500 mg of intravenous acyclovir was given every 8 hours. Two days later the patient was successfully weaned. Unfortunately she suffered a heart attack about a week later and died.
Discussion
Our case serves as a reminder that HSV-1 pneumonia may present as failure to wean from a respirator. Asymptomatic HSV-1 pneumonia presents clinically with dyspnea, fever, and hypoxemia, which may contribute to failure to wean.3, 4, 5 Recent antecedent mucocutaneous HSV-1, if present, may be a clue to HSV-1 pneumonia, but is not frequent.3, 6, 7 Asymptomatic HSV-1 shedding in the oropharynx may occur.2, 8
Diagnosis of HSV-1 pneumonia is best done by culture of pulmonary secretions. HSV-1 grows well on most viral culture media and remains the gold standard for diagnosis.5 Positive cytopathologic effects are usually achieved in 48 to 72 hours.2, 5 Polymerase chain reaction is a faster diagnostic technique (ie, approximately 24 hours), which provides sensitivity and specificity of 95% and 100%, respectively.9,10 Polymerase chain reaction may soon become the gold standard for diagnosing HSV-1 pneumonia. Chest radiograph patterns vary in cases of HSV-1 pneumonia and range from completely normal to infiltrates with no particular pattern.5 Once diagnosed, treatment of HSV-1 pneumonia is with acyclovir (Table I).5, 6, 7
Table I.
Clinical characteristics of HSV-1 pneumonia
Symptoms
Unexplained dyspnea
Failure to wean off a respiratory, especially in patients without preexisting lung disease
Signs
Unexplained hypoxemia with normal or near normal chest radiograph
Low-grade fever
Laboratory Tests
Arterial blood gas
↑ A-a gradient
Hypoxemia
Gallium scan
Bilateral symmetrical diffuse uptake
Indium scan
Bilateral symmetrical diffuse uptake
Spiral computed tomography
Normal or diffuse ground glass opacities
Chest radiograph
Normal or diffuse ground glass opacities
Our case reminds the physician that HSV-1 pneumonia may present failure to wean from a respirator. Treatment with acyclovir permitted our patient's successful wean after a long and unexplained failure to wean. We suggest that physicians consider HSV-1 pneumonia when encountering a patient who inexplicably fails to wean. HSV-1 should also be considered in patients with normal chest radiographs and unexplained hypoxemia. Appropriate viral cultures of HSV-1 should be obtained by bronchoalveolar lavage.5, 6, 7, 8
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From the Infectious Disease Division, Winthrop University Hospital, Mineola; and the State University of New York School of Medicine, Stony Brook, New York
☆ Reprint requests: Burke A. Cunha, MD, Chief, Infectious Disease Division, Winthrop University Hospital, Mineola, NY 11501.
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