ELECTROCARDIOGRAPHIC PREDICTION OF HYPERINFLATION IN CHILDREN

The mean frontal P wave axis in an electrocardiogram (ECG), which refl ects the atrial orientation in the thorax, is altered by the relations hip between atria and the diaphragm and, therefore, by hyperinflation. To examine this relationship, 102 children (ages 6-18) with asthma we re prospectively studied. Lung volumes were estimated by plethysmograp hy and a standard ECG obtained before and after bronchodilator. The me an thoracic gas volume (TGV) was 120.7 +/- 2.1% of predicted and the m ean 9 axis was 54.9 +/- 1.5 degrees. Sixty-two subjects (61%) had a '' vertical'' P axis (greater than or equal to 60 degrees). Of 27 subject s with moderate or severe hyperinflation (TGV greater than or equal to 130% predicted), 23 (85%) had a vertical P axis. As a measure of sign ificant hyperinflation, a vertical P axis had a sensitivity of 85%, sp ecificity of 49%, positive predictive value of 38% and a negative pred ictive 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 greater than or equal to 15% decrease in TGV also had a decrease in P axis, and 62/67 subjec ts (93%) with a decrease in P axis also had greater than or equal to 1 5% decrease in TGV. The sensitivity was 82%, specificity 81%, and posi tive predictive value 93% for a decrease in P axis as a measure of dec rease in TGV. A vertical P axis combined with a decrease in P axis aft er bronchodilator is highly sensitive and predictive for hyperinflatio n in children.