So just an update before I get to the real post: I’ve started my Emergency Medical Responder course, which is the most basic level one can work as a paramedic in BC, other provinces or countries call it EMT-B. The course is very similar to OFA3 and AMFR, in fact I think it’s best to say it’s a merger of the two courses with some slight differences and more advance protocols. For those who are curious about the differences/similarities between the courses, I will write a post on that once I am done the course.
I had a good class today, we were mostly running full cardiac arrest codes in class including transport. What I wanted to share are actually some videos our teacher showed us. I found them interesting because I’ve seen demonstrations or acting of what decorticate posturing and agonal breathing is like, but have never seen it in real life/outside of acting and photos. Another interesting topic is the infamous sudden death of an athlete taking a blow to the chest. Anyways I’ll start with the decorticate posturing and agonal breathing video.
The video shows some lifeguards having a photo session but ended up helping a near-drowning. You can see agonal breathing (1:31, 1:36) in the beginning before the third shock, and also decorticate posturing (2:26), with the arms and wrists flexing in after the first shock. This video goes to show the effectiveness of early access to CPR and defibrillation:
For those who don’t know:
Agonal breathing is ineffective breathing and often occurs in 40% of patients in cardiac arrest (AEM, 1992: 21;12). This “gasp of death” is caused by lack of oxygen to the anterior brain (responsible for complex sensory and neural functions and initiation/coordination of voluntary activity) called cerebrum. Therefore the scientific name for the cause is cerebral ischemia.
Decorticate Posturing is abnormal rigidity, extension of the legs, flexion of the arms to the body, and wrists and fingers bent and held to the chest. This is rated as 3 in the motor response part of the GCS scale and indicates brain damage to the corticospinal tract (the pathway between the brain and the spinal cord). There are many causes to decorticate posturing such as stroke, head injury, increased ICP, and brain tumor to name a few. In this case, it could be from lack of oxygen, or he may have hit his head (we really don’t know what happened to him other than he was found floating in the water).
This next video shows a very rare form of sudden death resulting from a sudden blunt blow to the chest called Commotio Cordis or Agitation of the Heart in Latin:
I was curious about commotio cordis and decided to do some light research to get more information about this almost surreal cardiac arrest. It seems almost mythical, something that belongs in the movies. During my search, I found an article from The New England’s Journal of Medicine called Blunt Impact to the Chest Leading to Sudden Death from Cardiac Arrest During Sports Activities by Barry J. Maron, et al. In the study, only 2 out of 19 patients were resuscitated (10.5%). What is interesting is that often the blunt blow doesn’t cause traumatic injury and that the casualties are usually healthy and absent of cardiac diseases. So I was curious as to how this sudden cardiac arrest occurs.
It appears that one has to be really “lucky” to go into cardiac arrest by a sudden blunt blow to the chest. Basic mechanism of injury for commotio cordis involves direct impact over the precordium (area of the chest just in front of the heart), and, yes, the “lucky” part: The person must be hit when their heart is in the T-wave phase. In other words, the heart must be specifically in the ascending phase of the T-wave which is a specific 10-30ms in the cardiac cycle. During this phase, the ventricles of the heart is undergoing repolarization. It is believed that during this phase, the heart is vulnerable for ventricular excitability and a hit can cause ventricular fibrillation resulting in cardiac arrest. So it seems that a single-punch-death-blow isn’t all that far fetched after all. However, you must have impeccable timing, down to the milliseconds to deliver this blow effectively.