Comparison of demographic, clinical, radiological characteristics and comorbidities in mechanically ventilated and nonventilated, adult patients admitted in ICU with confirmed diagnosis of influenza A (H1N1).

Introduction: Influenza A(H1N1) infection affected Indian population in 2009. Patients needed ICU admission and monitoring. Simple demographic, clinical and radiological variables are described in this article in mechanically ventilated and nonventilated patients.

Objectives: To describe and correlate demographic, clinical, radiographic characteristics and comorbidities in mechanically ventilated and nonventilated, adult patients admitted in ICU with confirmed diagnosis of Influenza A(H1N1) infection.

Material And Methods: Retrospective study of records of 100 RT-PCR confirmed patients with Influenza A (H1N1) infection from August 2009 to March 2010 was done. Each patient underwent an evaluation to determine demographic, clinical and radiographic features, comorbidities, mechanical ventilator required or not.

Results: 35 Patients required mechanical ventilation. 27 required IMV, 4 required NIMV while 4 patients initially were put on NIMV required IMV subsequently. 19 (40.42%) female patients required mechanical ventilator. Mean age of mechanically ventilated patients was 33 years, mean duration of illness was 7.9 days, mean duration of hospital stay was 6.8 days. 07 (20.00%) patients with pregnancy, 05 (14.29%) with DM, 05 (14.29%) with HT, 04/11.43%) with obesity required mechanical ventilator. 97.14% patients with fever, 88.54% with breathlessness, 11.43% with haemoptysis, 31.42% patients with throat pain required mechanical ventilator. However except Tachypnoea (p <0.01) no other symptom was statistically significant for mechanical ventilation 33(36.26%) patients with abnormal X ray,16 (80.00%) patients with right sided, 09(60.00%) patients with left sided and 40(71.43%) patients with bilateral disease required mechanical ventilator, right sided (p < 0.01) and bilateral (p <0.01) disease is statistically significant for requirement of mechanical ventilator. 33(47.14%) patients with lower zone involvement, 44 (67.70%) patients with middle zone and 23 (47.92%) patients with upper zone involvement required mechanical ventilator. Upper zone disease (p < 0.01) and middle zone disease (p < 0.01) is statistically significant for requirement of ventilator. 23 (47.92%) patients with right upper zone, 29 (42.64%) patients with right middle zone, 29 (46.77%) with left middle zone, 32 (42.67%) with right lower zone involvement required mechanical ventilator. RUZ (p < 0.01), RMZ (p < 0.01), LMZ (p < 0.001) and RLZ (p < 0.01) involvement had statistical significance for requirement of mechanical ventilator. 20 (33.89%) patients with patchy consolidation, 08 (36.36%) patients with reticulonodular and 05 (50.00%) patients with nodular pattern required mechanical ventilator however none of the pattern is statistically significant for mechanical ventilator. 08 (72.72%) patients with 6 zone involvement, 05 (50.00%) patients with single zone, 08 (40.00%)patients with 4 zone and 06 (33.33%) patients with 3 zone involvement required mechanical ventilator,however none was statistically significant for mechanical ventilator. All four patients requiring NIMV survived, while 28 died out of 31 on IMV.

Conclusions: Mechanical ventilation requirement was more in females, in presence of comorbidities like pregnancy, DM, HT, in presence of tachypnoea, in presence of bilateral disease and in presence of middle zone and right upper zone disease and with multiple zone disease. All patients with heart involvement required mechanical ventilator. If there is radiological finding of right upper zone involvement, then, there is more probability that these patients require mechanical ventilator for case management. Similarly, RMZ, LMZ and RLZ and cardiomegaly if shown in X-ray, the necessity of ventilator management is more.