Influenza pneumonia - A descriptive study

Objective: To describe the clinical features and complications of patients hospitalized with influenza during the 1999-2000 influenza season, Methods: We reviewed all cases of patients with influenza admitted to a lar ge metropolitan referral hospital during the 1999-2000 season. Results: Thirty-five adult patients (15 men and 20 women) tested positive f or influenza A by direct enzyme immunoassay. A fourfold to sevenfold increa se in the number of influenza cases was observed over previous years. Most patients had serious comorbid illnesses (88%), such as diabetes and chronic respiratory and heart disease, Seventeen patients developed pneumonia; the se patients tended to be older (mean +/- SD, 63 +/- 13 years vs 51 +/- 19 y ears, respectively p = 0.04) and had a higher incidence of chronic lung dis ease (41% vs 6%, respectively; p = 0.02) than the patients without pneumoni a. Shortness of breath was the only symptom that distinguished patients wit h pneumonia from those with an upper respiratory tract illness alone. Antiv iral treatment was begun 4 +/- 3 days from initiation of symptoms in patien ts with pneumonia and consisted of oseltamivir (35.2%), rimantadine (5.8%), or a combination of both (17.6%), Respiratory and/or blood culture results were positive in five patients (29%), Staphylococcus aureus was isolated i n five patients, and Streptococcus pneumoniae was isolated in one patient, Ten of the patients with pneumonia (58.8%) were admitted to the ICU, and 5 patients (29%) died. The length of ICU stay and mechanical ventilation were 28 +/- 26 days and 21.5 +/- 20.5 days, respectively. Death in most pneumon ia patients was attributed to respiratory failure. Conclusion: The recognized number of hospital admissions for influenza incr eased fourfold to sevenfold over previous years, most likely due to the imp lementation of rapid diagnostic tests for influenza, Patients with signs an d symptoms of influenza and shortness of breath should undergo chest radiog raphy. Hospitalization of patients with influenza pneumonia occurred in bot h previously healthy and immunocompromised patients and had a high mortalit y. S aureus was the most common bacterial isolate in patients with influenz a pneumonia, Empiric antibiotics with staphylococcal activity should be use d pending culture results pneumonia remains to be determined, in patients w ith influenza pneumonia. The effectiveness of oseltamivir and rimantadine i n treating patients with influenza pneumonia remains to be determined.