Abstract 88: Changes in Chest Compression Force Required to Achieve Adequate Compression Depth Throughout a Cardiac Arrest Resuscitation Event
Background: A recent study demonstrated decreases in compression depth over time suggesting rescuer performance decay, but remodeling of the chest secondary to compressions has not been excluded as a potential explanation. CPR is known to induce trauma, including broken ribs and pulmonary hemorrhage. Yet, the effects of these changes on chest wall compliance, and therefore the force required to achieve the same depth of chest compressions, is unknown.
Objective: To measure differences in the elastic force required to generate the same compression depth over time during actual in-hospital CPR.
Methods: Consecutive index adult in-hospital cardiac arrests from a single academic medical center were enrolled between June 2007 and May 2010, which were recorded using a CPR-sensing defibrillator (MRX with QCPR, Philips Healthcare). Cases were included if they had concurrently available accelerometer and force data, lasted more than 10 minutes, and had an average accelerometer displacement of at least 50 mm (to offset the expected mattress compression component of displacement). Data from each case were analyzed in 5 minute blocks, comparing elastic force required to reach 50 mm depths throughout the resuscitation.
Results: Fifty patients met inclusion criteria. The average age was 60±17 and 16(32%) were men. 27(54%) occurred in the ICU and the average BMI was 27.4±7.9 kg/m2. The average elastic force required to achieve an accelerometer displacement of 50 mm was 23.1±4.8 kg, and did not vary significantly over time in unadjusted analysis (see Figure). Paired analyses and cluster-adjusted multivariable logistic regression accounting for patient characteristics confirmed these results.
Conclusions: The elastic force required to achieve adequate chest compression depth does not significantly change over time. This supports the notion that measured decreases in compression depth over time are a product of rescuer performance decay and not changes in chest wall dynamics.
- © 2010 by American Heart Association, Inc.