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Electrocardiographic prediction of hyperinflation in children
S S Krishnan1, J Stewart, N Amin
1Department of Pediatrics, New York Medical College, Valhalla 10595, USA.
Insights
In children with asthma, a vertical P wave axis on an electrocardiogram (ECG) can indicate lung hyperinflation. This electrical marker, along with its change after bronchodilator treatment, helps assess lung volume changes.
Area of Science:
- Pediatric Pulmonology
- Cardiology
- Medical Imaging
Background:
- The P wave axis on an electrocardiogram (ECG) reflects atrial orientation and can be influenced by thoracic anatomy, including diaphragm position.
- Lung hyperinflation, common in pediatric asthma, alters intrathoracic pressures and may affect atrial electrical activity.
Purpose of the Study:
- To investigate the relationship between lung hyperinflation and the P wave axis in children with asthma.
- To evaluate the diagnostic utility of the P wave axis for detecting and quantifying hyperinflation before and after bronchodilator administration.
Main Methods:
- Prospective study of 102 children (ages 6-18) with asthma.
- Pulmonary function tests (plethysmography) to measure thoracic gas volume (TGV) and standard ECGs were performed before and after bronchodilator therapy.
- Statistical analysis to assess correlations between TGV and P wave axis measurements.
Main Results:
- Children with asthma exhibited significant hyperinflation (mean TGV 120.7% predicted).
- A vertical P wave axis (≥60 degrees) was observed in 61% of subjects and was highly prevalent (85%) in those with moderate to severe hyperinflation (TGV ≥130% predicted).
- Bronchodilator therapy reduced TGV and P wave axis, with changes in P wave axis effectively mirroring reductions in TGV.
Conclusions:
- A vertical P wave axis is a sensitive indicator of hyperinflation in pediatric asthma.
- Changes in the P wave axis following bronchodilator use correlate well with improvements in lung volumes, offering a non-invasive method to assess treatment response.
Abstract:
The mean frontal P wave axis in an electrocardiogram (ECG), which reflects the atrial orientation in the thorax, is altered by the relationship between atria and the diaphragm and, therefore, by hyperinflation. To examine this relationship, 102 children (ages 6-18) with asthma were prospectively studied. Lung volumes were estimated by plethysmography and a standard ECG obtained before and after bronchodilator. The mean thoracic gas volume (TGV) was 120.7 +/- 2.1% of predicted and the mean P axis was 54.9 +/- 1.5 degrees. Sixty-two subjects (61%) had a "vertical" P axis (> or = 60 degrees). Of 27 subjects with moderate or severe hyperinflation (TGV > or = 130% predicted), 23 (85%) had a vertical P axis. As a measure of significant hyperinflation, a vertical P axis had a sensitivity of 85%, specificity of 49%, positive predictive value of 38% and a negative predictive value of 90%. After nebulized albuterol, the mean TGV decreased to 96.4 +/- 1.3% predicted and the mean P axis decreased by 7.1 +/-1.6 degrees. Sixty-two of 76 subjects (82%) with > or = 15% decrease in TGV also had a decrease in P axis, and 62/67 subjects (93%) with a decrease in P axis also had > or = 15% decrease in TGV. The sensitivity was 82%, specificity 81%, and positive predictive value 93% for a decrease in P axis as a measure of decrease in TGV. A vertical P axis combined with a decrease in P axis after bronchodilator is highly sensitive and predictive for hyperinflation in children.