Vol. 25 Fall
By now most of you are aware of the “new” standards and changes in CPR. What many of you may not be aware of is that most lay people and even First-responders (Physicians and CPR instructors included!) are reluctant to perform the necessary mouth to mouth component. Of course this is mostly due to the intimate nature of the contact and anyone who has performed mouth to mouth knows exactly what I’m talking about. This has been a problem for most ‘out-of-hospital’ cardiac arrest victims whose very survival may depend on early intervention and defibrillation.
The major issue that seems to be supporting the ‘newer’ CCR (Cardio cerebral Resuscitation) is perfusion pressures. The pressures in question are in two areas; cardiothoracic perfusion (which is stipulated as the hemodynamic aspect) and cerebral perfusion (this is the neurological component) that is so critical to overall survival. These necessary pressures drop dramatically when the compressions are stopped, even for ventilation of the patient. Once chest compressions have been initiated, it takes time for these pressures to build up to necessary levels and with the halting of the pumping for rescue breathing there is just not enough sustainable pressures generated. This, according to the latest science, impairs the overall survivability without significant neurological deficit. This is really what we strive for in EMS as there is no success in a resuscitation that leaves the patient brain dead.
Some other criteria that oppose current practices are also called into question, namely early defibrillation, endotracheal intubation, and the ventilator cycles. Some studies have shown that, depending on when the rescuer arrives on the scene (plus or minus five minutes) it may be more beneficial to start compressions and give a full cycle of pumping BEFORE initiating electrical defibrillation (more than five minutes). This involves the conception that the first five minutes involves the ‘electrical phase’ of the cardiac arrest and defibrillation performed during this phase may be successful in restoring a perfusion rhythm. After this five minute window the patient is said to be in the ‘hemodynamic phase’ and defibrillation performed first (before chest compressions) often lands the patient in a non-perfusing “pulseless electrical activity” (PEA); formerly called EMD, “electro-mechanical dissociation” for you dinosaurs) or asystole (flat-line). This may be related to “re-perfusing” the heart as much of the blood still in the system is oxygenated. It has also been shown the endotracheal intubation may NOT need to be the highest priority. Studies show that bag-valve-mask delivered in appropriate time parameters should be sufficient. It also states that providers should be VERY aware of the ventilation rates that are being applied as too fast may be detrimental as this causes a decrease in venous return and perfusion pressures. Averages studied in-hospital and pre-hospital typically end up in the range around 36-37/minute, way over the recommended 12-15/minute. Remember, it’s the perfusion pressures we are trying to maintain.1
Some “test runs” are being done on this CCR concept as it is inconsistent with current American Heart Association guidelines. One local fire department here in the Las Vegas Valley has undertaken a new protocol for this concept under a trial run. Scott Vivier, an EMS Division Chief for the Henderson (NV) Fire Department, was recently quoted in a local neighbor paper stating “this new protocol will simplify CPR for citizens” and notes “demonstrable improvement has been shown since instituting the new CCR protocols.” (Summerlin View, vol. 17, num. 38, 11AA)
One additional protocol that may be of benefit to the out-of-hospital cardiac arrests is the use of hypothermic treatments. Using rationals similar to cold-water drowning and the mammalian diving reflex, administering ice-cold IV fluids to patients found in the hemodynamic post arrest and lowering their core body temps one-to-four percent may improve survivability by lowering cellular metabolic needs. (Vivier, Summerlin View, vol. 17, num. 38, 12AA) This needs to be continued in-hospital for up to 14 hours.
So where does this leave other providers relative to their treatment protocols? More research needs to be done of course. We may end up seeing instead of CPR or the ABC’s in initial management of cardiac arrest turned into a conceptual model of CCR and CBA (chest compressions-breathing-airway). This dramatically alters the way we currently approach patients in cardiac arrest and will greatly simplify the citizen participation (this is argued to increase citizen involvement and by making the process very straightforward for laypersons emphasizing rapid and continual compressions without mouth to mouth) causing more to get involved and assist. It is also clearly stated in the research that interruption of chest compressions (even for brief periods of time) can be lethal. This may be of issue to municipal providers who make patient removals from multi floor residences and have to use staircases (impossible to continue compressions and carry the patient) and some institution of mechanical compression devices must be considered. Those aside, look for changes in the current standards of how we approach and treat our field cardiac arrests.