Interposed abdominal compression-cardiopulmonary resuscitation: are we missing the mark in clinical trials?

Straightforward considerations of abdominal anatomy in human beings set tight constraints on the theoretically optimal technique for abdominal compressions during interposed abdominal compression (IAC)-CPR. The location and extent of the abdominal aorta lead naturally to the recommendation that IAC be applied at a level corresponding to the lower two thirds of the sterno-umbilical line. The force vector required to achieve contact compression of the abdominal aorta is inclined in the transverse plane at an angle of 11 degrees from the vertical toward the left. Such slightly angled compression subjects the abdominal aorta to maximally flattening; while the inferior vena cava on the right is sheltered somewhat from direct compression by the crest of the spine. Physics suggests that the optimal pressure for IAC is the same as the contact pressure required to best palpate the abdominal aortic pulse. Constraints of human anatomy also suggest an optimal posture for the rescuer applying IAC. A straight-arm technique from the left side is less tiring, so that the weight of the torso and a rocking motion can be used. Placement of the rescuer’s knees close to the victim’s side will help to support most of the rescuer’s weight and so avoid overly forceful abdominal compression. The proposed leftsided, angled technique for selective aortic compression is easy to teach, to remember, and to apply with minimal fatigue.