Association of severe acute lower respiratory tract infections with pulmonary hypertension in infants aged 2 months to 1 year, a prospective study

Introduction: Acute lower respiratory tract infection (LRTI) is the major cause of morbidity and mortality in infants. Acute LRTI is known to affect the pulmonary pressure. Noninvasive early diagnosis of pulmonary arterial hypertension (PAH) and intervention in infants with acute LRTI may reduce the progression of disease to advanced stage and improves the survival rate. Objective: To determine hospital based incidence and association of pulmonary hypertension in infants aged 2 months to 1 year with severe acute lower respiratory tract infections. Materials and Methods: A prospective cross sectional study was conducted in a tertiary care hospital of south India. The study included 80 infants aged between 2 months to 1 year, admitted in PICU with severe acute lower respiratory infections (diagnosed as per WHO criteria). Majority of cases included under acute LRTI were Bronchopneumonia (58), remaining 14 cases had bronchiolitis and 8 cases had wheeze associated lower respiratory infection (WALRI). Infants with congenital heart diseases, infants with PPHN, with portal hypertension and familial pulmonary hypertension are excluded from the study. Pulmonary pressure was measured using 2D Doppler Echocardiography once within 24 hours of admission in all study subjects. Repeat 2D Doppler ECHO was done after treatment of acute LRTI at the time of discharge in infants with pulmonary hypertension to know the degree of decrease in pulmonary pressures and outcome. Appropriate statistical methods were used to calculate the incidence. Results: There was a direct correlation between severe lower respiratory tract infections and pulmonary pressure. Hospital based incidence of pulmonary arterial hypertension in severe acute LRTI was 56.3%. Infants between age group of 2-4 months had higher incidence of PAH, which contributes to 47.5%. Incidence of PAH in males was 58.3% and in females was 50%. Incidence of PAH in bronchopneumonia was 53.4%, in Bronchiolitis it was 64.2% and in WALRI it was 62.5%. Repeat 2D Doppler ECHO after treatment of severe acute LRTI revealed decrease in pulmonary pressure. Conclusion: This study revealed a direct correlation between severe lower respiratory tract infections and increase in pulmonary pressure. Treatment of severe acute LRTI has resulted in decrease in pulmonary pressure. 2D Doppler Echocardiography may be a simple non invasive tool to diagnose pulmonary hypertension in children with severe LRTI.