Abstract 134: Standard CPR versus CPR with an Intrathoracic Pressure Regulator versus Active Compression Decompression CPR Plus an Impedance Threshold Device During Out-of-Hospital Cardiac Arrest: An Acute Hemodynamic Clinical Feasibility Study
Background: During cardiopulmonary resuscitation (CPR), augmentation of negative intrathoracic pressure following compressions lowers intracranial pressure, enhances cardiac preload, and increases cardiac and cerebral perfusion.
Methods: This feasibility study, performed under FDA Investigation Device Exemption (21CFR812), focused on two new CPR methods to lower intrathoracic pressure in patients with out-of-hospital cardiac arrest. Standard (S)-CPR was compared with (1) S-CPR with an intrathoracic pressure regulator designed to lower airway pressures to -12cmH2O after positive pressure ventilation (S-CPR+IPR) and (2) active compression decompression (ACD) CPR with a new adhesive-based device + impedance threshold device (ACD+ITD). Subjects were prospectively randomized and met final inclusion criteria if femoral arterial access was established in the field and ≥5 minutes of hemodynamic data were recorded. Subjects who presented in unwitnessed asystolic arrest were excluded. Systolic blood pressure (SBP) was the primary endpoint. A one-way ANOVA was used for statistical comparison with p<0.05 considered statistically significant.
Results: Of 48 initially enrolled patients, 15 met final inclusion criteria (3 S-CPR+IPR, 6 ACD+ITD, and 6 S-CPR). The time from 911-call to first measured pressures averaged 41 ± 13 minutes (range was 24-73 min), in part due to design of the study. SBP increased with S-CPR+IPR to 141 ± 11mmHg compared to 63 ± 8mmHg with ACD+ITD (p<0.01) and 59 ± 12mmHg with S-CPR (p<0.01). DBP was 52 ± 28 with S-CPR+IPR, 16 ± 5 with ACD+ITD, and 21 ± 7 with S-CPR (NS between groups). Peak EtCO2, a measure of circulation during CPR, trended higher with S-CPR+IPR (48 ± 24mmHg) and ACD+ITD (42 ± 7mmHg) compared with S-CPR (38 ± 212mmHg), but the differences were not significant. Interpretation is limited due to the low number of patients meeting final enrollment.
Conclusion: Use of S-CPR+IPR provided the highest SBP observed in this feasibility study. Augmentation of negative intrathoracic pressure with S-CPR+IPR and ACD+ITD provided higher blood pressure and ETCO2 values than S-CPR alone. Further studies are needed to correlate improved BP and perfusion associated with these new devices with long-term clinical outcomes.
- © 2013 by American Heart Association, Inc.