-30°→90°
Dominant QRS direction (positive or negative) can be used to approximate<unk> 
Normal<unk>  if positive QRS in leads I and aVF
Normal<unk>  if positive QRS in leads I and aVF
ECG axis
ECG rhythms
Vital signs 
ECG Stampede
Ventilation modes
Apneic oxygenation
Apgar score
T wave changes