An increase in rib fractures was observed at autopsy in infants who had undergone CPR, which is temporally related to the introduction of guidelines stressing the hand-encircling two-thumb method of CPR and compression depths of 1/3 – 1/2 the anteroposterior diameter of the chest, which has been shown in previous studies to produce higher coronary perfusion pressures and more consistently correct depth and force of compression than the “two-finger” technique.
Previous posts here have reported a CT scan-based mathematical modelling study that suggested compressing to 1/3 anteroposterior chest wall diameter should provide a superior ejection fraction to 1/4 depth and should generate less risk for over-compression than 1/2 AP compression depth, and another post described a small case series of 6 PICU patients requiring CPR for cardiac arrest due to primary cardiac disease in which blood pressure as measured by an arterial line increased when the depth of chest compression was increased from one third to one half of the chest wall diameter (using the hand-encircling method).
What should we do about this? I think the take-home message is to be mindful of the risk of rib fractures and to avoid over-compression, but to follow the guidelines. Another valuable point was made by the authors:

“Regardless of the reason for the increased incidence, the possibility of CPR-related rib fractures needs to be seriously considered in the evaluation of any infant presenting with rib fractures, when there is a history of CPR, so as not to misinterpret the finding as evidence of non-accidental/inflicted injury.”

OBJECTIVE: A recent increase in the number of infants presenting at autopsy with rib fractures associated with cardio-pulmonary resuscitation (CPR) precipitated a study to determine whether such a phenomenon was related to recent revision of paediatric resuscitation guidelines.

METHODS: We conducted a review of autopsy reports from 1997 to 2008 on 571 infants who had CPR performed prior to death.

RESULTS: Analysis of the study population revealed CPR-related rib fractures in 19 infants (3.3%), 14 of whom died in the 2006-2008 period. The difference in annual frequency of CPR-related fractures between the periods before and after revision of paediatric CPR guidelines was statistically highly significant.

CONCLUSIONS: The findings indicate that CPR-associated rib fractures have become more frequent in infants since changes in CPR techniques were introduced in 2005. This has important implications for both clinicians and pathologists in their assessment of rib fractures in this patient population.

Increased incidence of CPR-related rib fractures in infants-Is it related to changes in CPR technique?
Resuscitation. 2011 May;82(5):545-8