Head-Up CPR May Improve Neurologically Intact Survival Rates

Device-assisted head-up CPR offers a more complex approach that involves timed elevations and specific sequences for elevating the head, thorax and shoulders. Photo courtesy AdvancedCPR Solutions
Device-assisted head-up CPR offers a more complex approach that involves timed elevations and specific sequences for elevating the head, thorax and shoulders. Photo courtesy AdvancedCPR Solutions

Head-up CPR is a novel concept in resuscitation that has the potential to improve neurologically intact survival after cardiac arrest.

Inspired by the clinical question of whether patients in cardiac arrest should be transported either head-up or feet-up in a small elevator, an initial animal study was performed in 2014. In this swine model of cardiac arrest, pigs underwent five-minute periods of automated CPR with an impedance threshold device (ITD-16) in the traditional supine position, then with a 30-degree whole-body head-up tilt, and then a 30-degree whole-body head-down tilt.

The cerebral blood flow and cerebral perfusion pressures (CerPP) were higher in the whole-body tilt-up group vs. the flat group. Intracranial pressure (ICP) was also lower in the whole-body head-up tilt group. Notably, CerPP and ICP were lower and higher, respectively, in the whole-body head-down tilt.1

Subsequent studies refined the body position over a longer period of CPR, where the head and thorax of the pig was elevated during 22 minutes of active compression-decompression (ACD) CPR plus use of an ITD-16 (ACD+ITD) to reduce venous pooling in the lower extremities during resuscitation. CerPP was higher and sustained over this entire period of time in the ACD+ITD head-up group vs. the flat group.2 (See Figure 1.)

Further studies using a similar protocol for a prolonged period of head-up ACD+ITD CPR showed a doubling of cerebral blood after 15 minutes of CPR and also replicated the finding of higher CerPP pressures seen in previous studies.3

The primary mechanism of benefit behind head-up CPR is the use of gravity to enhance venous drainage not only from the brain and cerebral venous sinuses, but also the paravertebral venous plexus, thereby decreasing ICP and creating potential for the forward flow of blood.1,3,4

A secondary mechanism of benefit is thought to be the concept of decreasing the pressure transmitted to the brain via both the venous and arterial vasculature during CPR, effectively reducing a concussive injury with compression.

A third mechanism involves redistributing blood flow through the lungs in a manner similar to what occurs when patients with heart failure sit upright.

Animal studies show head-up CPR is dependent on circulatory adjuncts during CPR, such as the ITD-16 to drive blood “uphill” to maintain an adequate mean arterial blood pressure during resuscitation. When head-up standard CPR is performed, CerPP during resuscitation has been reported in the range of 7–10% of baseline CerPP values.2,5 This is compared to 50–60% of baseline CerPP values when head-up CPR is performed with circulatory adjuncts, such as ACD+ITD CPR or CPR performed with both the LUCAS mechanical chest compression device combined with use of the ITD-16.1–3

Other important considerations when performing head-up CPR includes: performing CPR flat before elevation, which primes the cardio-cerebral circuit; and to use caution when elevating the entire body over a long CPR effort, as blood likely pools in the lower extremities over time.6,7

The finding of lowered ICP and higher CerPP with head-up CPR has subsequently been replicated in a human cadaver model, the strongest translational evidence to date that head-up CPR is ready to move forward into humans in active cardiac arrest.8

More recent animal studies have focused on the optimal head-up CPR height and timing of head and thorax elevation. To date, no optimal angle has been determined,however a sequence effect has emerged, where animals treated with a controlled progressive elevation after two minutes of “priming”—to a final head height of 22 cm and a heart height of 9 cm—had sustained CerPPs and also higher coronary perfusion pressures > 70% of baseline values after > 15 minutes of ACD+ITD CPR.9,10

Most recently, head-up CPR has been incorporated into bundles of care in Palm Beach County, Fla., and Rialto, Calif.

As part of these bundles, survival rates in these two EMS systems have essentially doubled. Head-up CPR, when applied correctly and as part of a bundle of care, has the potential to improve neurologically intact survival rates after cardiac arrest.

References

1. Debaty G, Shin SD, Metzger A, et al. Tilting for perfusion: Head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest. Resuscitation. 2015;87:38–43.

2. Ryu HH, Moore JC, Yannopoulos D, et al. The effect of head up cardiopulmonary resuscitation on cerebral and systemic hemodynamics. Resuscitation. 2016;102:29–34.

3. Moore JC, Segal N, Lick MC, et al. Head and thorax elevation during active compression decompression cardiopulmonary resuscitation with an impedance threshold device improves cerebral perfusion in a swine model of prolonged cardiac arrest. Resuscitation. 2017;121:195–200.

4. Guerci AD, Shi AY, Levin H, et al. Transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs. Circ Res. 1985;56(1):20–30.

5. Putzer G, Braun P, Martini J, et al. Effects of head-up vs. supine CPR on cerebral oxygenation and cerebral metabolism—A prospective, randomized porcine study. Resuscitation. 2018;128:51–55.

6. Park YJ, Shin SD, Song KJ, et al. Abstract 18341: Worsened survival with head-up positional cardiopulmonary resuscitation in a porcine cardiac arrest model. Circulation. 2016;134(Suppl 1):A18341.

7. Moore JC, Segal N, Debaty G, et al. The “do’s and don’ts” of head up CPR: Lessons learned from the animal laboratory. Resuscitation. 2018;129:e6–e7.

8. Moore JC, Holley J, Segal N, et al. Consistent head up cardiopulmonary resuscitation haemodynamics are observed across porcine and human cadaver translational models. Resuscitation. 2018;132:133–139.

9. Moore JC, Salverda B, Lick M, et al. Abstract 17: Controlled progressive elevation maximizes cerebral perfusion pressure during head up CPR in a swine model of cardiac arrest. Circulation. 2018;138(Suppl 2):A17.

10. Rojas-Salvador C, Moore J, Salverda B, et al. Controlled fast head and thorax elevation improves cerebral perfusion pressure during active compression and decompression CPR with an impedance threshold device in a porcine model of cardiac arrest. [Abstract #35.] in Berry C, Kupas D, Olaf M, et al. Abstracts for the 2019 NAEMSP Scientific Assembly. Prehosp Emerg Care. 2018:1-251.

Figure 1: Cerebral perfusion pressures in animals treated with 22 minutes of four styles of CPR2

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