[Clinical characteristics of patients with infection due to Influenza A (H1N1) 2009 and critical pathology].

Objective: Retrospective, observational study in children hospitalized due to Influenza A (H1N1) between October 2009 and February 2010, emphasizing on those who required intensive therapy.

Material And Methods: Risk factors, symptoms, course, complications, mortality, time of disappearance of RT-PCR Influenza A (H1N1), average length of stay and duration of treatment with oseltamivir, were studied, comparing critically ill patients (group I) with the rest of hospitalized patients (group II).

Results: A total of 38 children, with a mean age of 5.03±4.6 years were admitted during the study period. Six patients required intensive care, 83.3% had risk factors for influenza A (H1N1) compared with 62.5% in group II. Fever > 38°C was the predominant symptom (92.1%). Respiratory symptoms were significantly more frequent in group I (83.3% vs. 33.6; P<.01). Two critically ill patients required mechanical ventilation due to ARDS (acute respiratory distress syndrome). One patient with exacerbation of chronic respiratory failure responded favourably to high-flow oxygen. One patient developed fulminant myocarditis and required ECMO (Extracorporeal Membrane Oxygenation) because of secondary cardiogenic shock, which developed into multiple organ dysfunction and brain death. Oseltamivir therapy was given for an average of 8.6 days in group I and 4.5 days in group II (P<.05), checking the negativity of RT-PCR Influenza A (H1N1) in 7±2 days. The average stay was significantly higher in group I. Two patients admitted to PICU died.

Conclusions: The presence of risk factors increases the likelihood of unfavourable outcome: high mortality among patients requiring intensive care. Monitoring of RT-PCR Influenza A (H1N1) could help establish the duration of isolation measures.