# Survival with one versus three centimeters of active decompression during automated head-up CPR in a porcine cardiac arrest model

## TL;DR

A study in pigs found that using 3 cm of active lift during a special CPR technique improved survival and blood flow more than using 1 cm.

## Contribution

This study identifies that 3 cm of active lift during automated head-up CPR improves survival and hemodynamics compared to 1 cm.

## Key findings

- 24-hour survival was 41.7% with 3 cm active lift versus 16.7% with 1 cm.
- Return of spontaneous circulation occurred in all pigs with 3 cm active lift but only half with 1 cm.
- Hemodynamics and other physiological parameters were significantly better with 3 cm active lift.

## Abstract

Automated head-up (AHUP) CPR, combining controlled head/thorax elevation, active compression-decompression CPR, and an impedance threshold device, has shown improved survival with favorable neurological outcomes versus conventional (C) CPR. The optimal amount of active lift (AD) during AHUP-CPR to optimize survival remains unknown. This study focused primarily on 24-h survival with 1-cm of active lift (AL-1 cm) with a rectilinear waveform versus 3-cm of active lift (AL-3 cm) with a trapezoidal waveform during AHUP-CPR.

Anesthetized pigs (n = 24, ∼40 kg) were randomized to AL-1 cm or AL-3 cm after 10 min of ventricular fibrillation. CPR began with 2 min of C-CPR (21% AP depth, sinusoidal waveform, 100/min), followed by 18 min of AHUP-CPR using the assigned AL. Asynchronous ventilation (10 ml/kg, 10/min) was provided. Epinephrine and amiodarone were administered after 19 min of CPR with defibrillation 1 min later. Primary outcome: 24-h survival; Secondary outcomes: return of spontaneous circulation (ROSC), hemodynamics, epinephrine response, and neurological function (Neurological Deficit Score [NDS], 0 = normal, 320 = death). Statistical analyses included t-test, Kaplan-Meier, log-rank, and Mann-Whitney U tests.

ROSC occurred in 6/12 pigs with AL-1 cm vs 12/12 with AL-3 cm (p = 0.03), and 24-h survival rates were 16.7% vs 41.7%, respectively (p = 0.04). Hemodynamics, ETCO2, epinephrine response, and changes in rSO2 values were significantly higher with AL-3 cm. NDS was 286 ± 79 (AL-1 cm) vs 213 ± 130 (AL-3 cm, p = 0.09).

24-h survival rates were significantly higher with AL-3 cm vs AL-1 cm during AHUP-CPR. Together with improved hemodynamics observed with AL-3 cm, these outcomes underscore the critical importance of AL-3 cm to optimize AHUP-CPR.