Proper compression landmark and depth for cardiopulmonary resuscitation in patients with pectus excavatum: a study using CT.

Objective: To determine by chest CT the proper compression landmark and depth for cardiopulmonary resuscitation in patients with pectus excavatum (PE).
Methods: The chest CT of 22 patients with PE (mean age=27 years; range 16-53 years, 10 male) from March 2002 to September 2011 were retrospectively evaluated as follows: length of sternum, external thickness/internal thickness (ET/IT) of the chest and the intrathoracic structures in the level of lower half (LH) of the sternum. In addition, Haller index (HI) and the degree of leftward displacement of the heart were measured. Finally, variables were also measured in an age/sex-matched control group (n=22) with no evidence of any chest wall deformity.
Results: The sternal length was not different and LH of the sternum was adequate to compress left ventricle (LV) in both groups. Patients had a significant higher HI and showed a greater leftward displacement of LV centre with a mean difference of 11 mm. PE patients showed a lesser ET/IT with a mean difference of approximately 20 mm than controls (mean ET/IT=174±18/70±10 mm vs 199±23/93±15 mm, p<0.001).
Conclusions: The LH of the sternum is an appropriate chest compression landmark in PE patients to compress LV, although the centre of LV shows slightly leftward displacement. Since PE patients have sunken chest, a 3-4 cm may be the proper compression depth in the patients when considering the current compression guideline in normal subjects is 5-6 cm.
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