Study of application of Non Invasive Ventilation in patients of severe pneumonia and acute respiratory failure caused by novel influenza A H1N1 virus

Abstract

Background: Respiratory system is the most common organ system affected in patients of H1N1influenza. Many patients requires mechanical ventilation for treatment as they develop ALI/ARDS due to primary viral or secondary bacterial pneumonia. In resource poor countries like us, providing ICU ventilator to all patients can produce a difficult task for health care system. Noninvasive ventilation can be an option provided appropriate patients are chooses at right stage of disease-probably in early stage of acute hypoxic respiratory failure. Aim: (1) To identify the patients suitable for non-invasive ventilation in patients of swine flu with signs of respiratory failure (2) To study outcome of NIV in these patients with aim to identify factors for the so called “late failure of NIV”. Materials and Methods: This study is meant to analyze data from patients of Novel H1N1 influenza patients admitted to swine flu isolation ward during January to December 2015 at PDU Hospital, Rajkot. From 650 patients admitted as suspected case, 283 were confirmed by RTPCR. Among 84 patients who were offered NIV 43 died during course of treatment. It is a retrospective study to analyze the patients who remains stable on NIV for at least 24 hrs. There were 66 such patients. Results: Out of 66 patients studied, 40 successfully treated with NIV. After initial 24 hrs factors which were statistically significantly associated with NIV late failure were-pregnancy (including postpartum period), tachycardia on admission and high total count during course of treatment (suggesting developing bacterial pneumonia). Conclusion: NIV can be used in selected patients of viral pneumonia. In pregnant or postpartum patients NIV should be used with caution. Signs of developing of bacterial pneumonia and MODS herald the chances of NIV failure. Co morbidities are not a strong predictor for NIV failure. Avoiding intubation can decrease complications particularly in immunocompromised patients. Use of steroid does not have significant effect on respiratory function improvement. Key words: H1N1 influenza A infection, severe pneumonia, NIV late failure