Radiological assessment of the adult chest: implications for chest compressions.

The recommended depth for chest compression during adult cardiopulmonary resuscitation (CPR) is 4-5 cm, and for children one-third the anterior-posterior (AP) chest diameter. A compression depth of one-third of the AP chest diameter has also been suggested for adult CPR. We have assessed chest CT scans to measure what proportion of the adult AP chest diameter is compressed during CPR. Measurements of AP diameter of chest CT scans were taken from the skin anteriorly at the middle of the lower half of the sternum, perpendicularly to the skin on the posterior thorax. The anatomical structure that would be compressed at this level was also noted. One hundred consecutive CT scans were examined (66 males and 34 females). The age (mean +/- S.D.) was 68+/-12 years. AP chest diameter was 253 +/- 27 mm for males and 235 +/- 30 mm for females. The proportion of total AP chest diameter compressed with current compressions is 15.8-19.8% for males and 17.0-21.3% for females. The commonest anatomical structures that would be compressed are the ascending aorta (38%) and the top of the left atrium (36%). There is also a wide anatomical variation in the shape of the adult chest. A chest compression depth of 4-5 cm in adults equates to approximately one-fifth of the AP diameter of the adult chest.