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Effective pulmonary blood flow in children with acute asthma attack requiring hospitalization
1Division of Paediatrics, United Medical School of Guy's Hospital, University of London, England.
Insights
Effective pulmonary blood flow (EPBF) accurately estimates ventilation-perfusion mismatch in children with asthma. Salbutamol treatment significantly improved EPBF, indicating better lung function and gas exchange.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Medical Diagnostics
Background:
- Acute obstructive lung disease in children impairs gas exchange due to ventilation-perfusion mismatch and bronchoconstriction.
- Standard lung function tests do not fully capture gas exchange abnormalities.
- Effective pulmonary blood flow (EPBF) offers a noninvasive method to estimate ventilation-perfusion mismatch.
Purpose of the Study:
- To measure EPBF in children with acute severe asthma.
- To assess the response to nebulized salbutamol using EPBF.
- To determine if baseline EPBF predicts treatment-induced changes.
Main Methods:
- Twenty-four children with acute asthma underwent spirometry and EPBF measurements (argon freon-22 rebreathing technique) before and after salbutamol.
- Eighteen patients were re-tested upon recovery; 4 were on methylxanthines.
- EPBF was measured using triplicate tests to assess variability.
Main Results:
- Forced expiratory volume in 1 sec (FEV1) improved significantly after salbutamol and recovery.
- EPBF was reduced in acute asthma compared to recovered states (P = 0.009), except in children on methylxanthines.
- Salbutamol significantly increased EPBF (P = 0.0003), indicating improved distribution of blood flow to ventilated lung areas.
Conclusions:
- EPBF is a valuable tool for assessing ventilation-perfusion mismatch in pediatric asthma.
- Nebulized salbutamol effectively improves EPBF in children with acute asthma.
- Changes in EPBF correlate with clinical improvement and lung function post-treatment.
Abstract:
In children with acute obstructive lung disease gas exchange is affected by ventilation-perfusion mismatch and the degree of bronchoconstriction. Standard lung function measurements do not reflect the impairment in gas exchange. Alternatively, the effective pulmonary blood flow (EPBF), that is, the proportion of the cardiac output that is supplying well-ventilated lung units, can give accurate and noninvasive estimates of ventilation-perfusion mismatch. We measured EPBF with the argon freon-22 rebreathing technique in children with acute severe asthma to assess their response to nebulized salbutamol and to determine whether induced changes in the EPBF could be predicted from baseline measurements. Twenty-four children admitted with an acute asthma attack had spirometry and triplicate EPBF measurements before and after nebulized salbutamol. Eighteen patients had repeated tests 50 days later when fully recovered; 4 patients were taking methylxanthines on at least one occasion. The mean forced expiratory volume in 1 sec (FEV1) rose from 55% of predicted to 66% after salbutamol and to 83% with recovery. The mean coefficients of variation for EPBF measurements on the three test occasions were 11.3%, 8.2%, and 9%. Except in children on methylxanthines, the EPBF values were reduced during the acute asthma attack (median, 2.53 L/min/m2; range, 1.99-3.60 L/min/m2) compared with paired values obtained after recovery (median, 2.89 L/min/m2; range, 2.28-4.04 L/min/m2) (P = 0.009). Salbutamol caused a highly significant increase in EPBF from 2.88 L/min/m2 (range, 1.86-3.80) before treatment to 3.34 L/min/m2 (range, 2.26-4.65) immediately afterwards (P = 0.0003).(ABSTRACT TRUNCATED AT 250 WORDS)