Evaluation of the Neonatal Resuscitation Program's recommended chest compression depth using computerized tomography imaging

Background: Neonatal Resuscitation Program (NRP) guidelines recommend chest compression depths of 1/3 the anterior-posterior (AP) chest depth. Appropriateness of this recommendation has not been rigorously assessed.

Objective: To compare the efficacy and safety of neonatal chest compression depths of 1/4, 1/3, and 1/2 AP chest depth during cardiopulmonary resuscitation.

Design/methods: Anterior-posterior internal and external chest depth, heart dimensions, and non-cardiac thoracic tissue depth were measured from neonatal chest CTs. Using these measurements, residual internal chest depth, the remaining depth of the chest between the sternum and spine after external compression, was calculated for compression depths of 1/4, 1/3 and 1/2 anterior-posterior chest depth. Compression sufficient to compress the chest to <10mm of residual internal chest depth was defined as over-compression. Using a mathematic model, an estimated ejection fraction (EF) was calculated for each chest compression depth. Compression inadequate to obtain a predicted 50% EF was defined as under-compression. Descriptive statistics, Fisher's exact test and Student's t-test were used to analyze data, where appropriate.

Results: Fifty-four neonatal chest CT scans were evaluated. Estimated chest compression induced EF increased incrementally with increasing chest compression depth (EF was 51+/-3% with 1/4 AP chest depth vs 69+/-3% with 1/3 AP chest depth, and 106% with 1/2 AP chest depth, p<0.001). Under-compression was predicted in 29/54 patients with 1/4 AP compression depth, but none of the patients with 1/3 or 1/2 AP compression depth, p<0.001. Over-compression, or lack of adequate residual chest depth, was predicted in 49/54 patients with 1/2 AP compression depth, but none of the patients with 1/4 or 1/3 AP compression depth, p<0.001.

Conclusions: Mathematical modeling based upon neonatal chest CT scan dimensions suggests that current NRP chest compression recommendations of 1/3 AP chest depth should be more effective than 1/4 compression depth, and safer than 1/2 AP compression depth.