Cardiac & Resuscitation, Columns, Patient Care

Tilt Angle Significantly Affects CPR

Issue 3 and Volume 40.

The Research

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;87:38–34.

The Science

The authors of this study had previously noted elevated pressures inside the brain, intracranial pressure (ICP), and hypothesized that raising the head during resuscitation could lower said pressure. They studied 22 pigs that were placed into v fib. The pigs and a LUCAS mechanical CPR device were bolted to a backboard and secured to a table that could be tilted in increments from 0–50 degrees. All pigs were placed in untreated v fib for six minutes followed by two minutes of CPR with an impedance threshold device (ITD) in a horizontal position.

After six minutes of untreated v fib, CPR was performed on 14 pigs at 0 degrees, 30 degrees head up and 30 degrees head down. Microspheres were used to measure organ blood flow in eight pigs. ITD CPR was performed on eight additional pigs at 0, 20, 30, 40 and 50 degrees head up.

They discovered that coronary and cerebral perfusion increased significantly when tilting the table upwards. With 0, 10, 20, 30, 40 and 50 degrees head up tilt, ICP values were 21 ± 2, 16 ± 2, 10 ± 2, 5 ± 2, 0 ± 2, −5 ± 2 respectively (p < 0.001). Tilting the head down resulted in significantly elevated ICP and decreased brain perfusion.

They concluded that cerebral perfusion was significantly affected by the tilt angle of the pig during CPR.

Doc Wesley Comments

My first reaction when I read this study was, “Why didn’t I think of that?” We’ve known for decades that raising the head of the bed is the first step in lowering the pressure in the brain of patients with head injuries. Cardiac arrest research was initially oriented with the goal of resuscitating the heart. Today, we realize there’s no benefit to getting the heart back if the patient is left with poor neurological outcome.

Blood flow to the brain occurs during systole, or in an arrest situation, when we compress on the chest. During CPR, there’s diminished venous drainage due to the body being level. Venous drainage occurs passively but is promoted by raising the head above the heart. The placement of an ITD enhances venous drainage and promotes blood return to the heart. Each time we compress on the chest, a hammerhead of pressure pounds the brain—which is already in shock. This has led some to theorize that traditional CPR may actually harm the brain, as a result of increased cerebral pressure and decreased perfusion.

In this study, the researchers removed the LUCAS for a short period during the 30-degree head up phase and documented that it significantly augmented the effect of the tilt. These same researchers have also completed a study showing that tilting the head upward improves neurological outcome in resuscitated pigs.

Earlier this year, Karen and I, along with several medical directors from across the country, had the opportunity to witness this effect first-hand at an event hosted by Advanced Circulatory System, the maker of the ResQPOD  ITD (of which I have no financial involvement).

Frankly? I was blown away. It just makes sense. Other medical directors and I are in the process of determining how it could be implemented in the field. Using current technology, it seems quite possible to tilt the body at least 30 degrees during both manual and mechanical CPR. This could very well become the new standard for CPR delivery.

Medic Wesley Comments

After 34 years in EMS, and multiple changes in CPR and resuscitation guidelines, I tend to take new updates with a “ho-hum” attitude. This time, I was able to witness the science.

By tilting the head of the subject during compression, the increased ICP seen with manual and mechanical CPR wasn’t present. It’s so simple, as Doc states. Why hasn’t it been thought of before?

We seemed so focused on timing of breaths, quality compressions and early defibrillation that the mechanical damage done to the brain never seemed to come up. Pushing hard and fast may help the heart but at the same time it may actually be harming our patient’s brain. Now that’s just a supposition on my part. But it does bode well for looking at everything from—pardon the pun—a different angle.

Using the current science of compressions, along with the new information suggested in this study, this may be the complete package when it comes to successful resuscitation with good neurological outcome. Any of you who are inventors should probably start figuring out a device for CPR that supports the mechanical device and elevates the patient’s head. After seeing the success of this study, I’m relatively certain we’ll be looking for a way to implement it in our ambulances soon.