Dr Ian Drennan

Ian Drennan has a PhD in clinical medicine from the University of Toronto with a focus on resuscitation sciences. He works as an Advanced Care Paramedic with York Region Paramedic Services and an instructor with Sunnybrook Centre for Prehospital Medicine. Ian also holds a part-time faculty position in the health sciences department at Georgian College. His thesis is focused on the development of clinical prediction rules and the treatment of out-of-hospital cardiac arrest patients. Other research interests include clinical aspects of prehospital care including community paramedicine, trauma, and sepsis. He is experienced in research methodology in systematic reviews, observational research through the use of large epidemiologic datasets, and randomized controlled trials in the prehospital setting. Ian has received funding from the Canadian Institute of Health Research (CIHR) and the Heart and Stroke Foundation of Canada, and is the past recipient of a 2014 Young Investigator Award from the American Heart Association. In addition to his PhD work, Ian is a member of a number of committees related to paramedic practice and research. He currently sits as a member of the International Liaison Committee of Resuscitation (ILCOR) Advanced Life Support (ALS) taskforce. and a writing group member for the 2015 and 2020 American Heart Association Guidelines for CPR and ECC. Ian can be reached at ian.drennan@sunnybrook.ca . Follow Ian on Twitter @IanR_Drennan. View his research on PubMed, ResearchGate or ResearcherID

We know that in cardiac arrest, basic life support care –  CPR & defibrillation – saves lives.

With respect to CPR, we want to make sure it’s high quality by optimizing rate (100 to 120 compressions/minute), depth (4.5 to 5.5cm), and minimizing pauses (on the chest >60% of each minute, but high performing services aim for >80%). If you can use them, use CPR feedback devices (AHA 2020).

As part of the conversation about BLS care, we must talk about effective ventilation, and some of the literature is suggesting that we actually do a poor job ventilating our cardiac arrest patients (Chang et al. Resuscitation 2019. 141: 174-181).

In a routine cardiac arrest patient, with effective basic life support care/ventilation, there is no need to prioritize putting in an advanced airway. There are opportunity costs that should be evaluated when making the decision to manage the airway more aggressively; when you spend time inserting an advanced airway upfront it often takes away from other, perhaps more important interventions.

Airways

There are a few observational studies that examined advanced airways and their relationship with patient outcomes. Due to their design however, they have significant limitations. Cardiac arrest management is algorithmic, and by the time you get to the airway in the cardiac arrest algorithm, these patients have been in cardiac arrest for a long time. Those who don’t get an advanced airway usually don’t because they are not in cardiac arrest long enough. It’s therefore impossible from observational studies to determine if the outcome is due to the airway, or due to being in cardiac arrest for a long time. This is something called resuscitation time bias, and cannot be accounted for in observational research studies (Andersen et al. Resuscitation 2018).

Wang (2018) JAMA; Benger (2018) JAMA; Jabre (2018) JAMA

Importantly, we should be measuring our first-pass success rate. The more attempts you take, the worse outcomes become. If your first pass success rate is low, it’s probably best to place a SGA. Having said that, there are a subset of patients who will be impossible/difficult to ventilate without an ETT.

In cardiac arrest, there isn’t a one size fits all approach with respect to airway management. You need to use a tool that will allow you to ventilate properly. Overall, the evidence would say that there’s not much difference between BVM, SGA, & ETT.

One thing that is worth considering is that BVM ventilations are hard. Where possible providers should ensure they have properly positioned the patient prior to ventilation, should use a 2-person ventilation technique, and should use ETCO2 feedback with waveform capnography to monitor ventilations. That being said, it is still difficult to ventilate without some degree of gastric insufflation and the longer you ventilate a cardiac arrest patient the more you should consider insertion of an advanced airway. It reduces gastric insufflation, avoiding associated complications, allows for accurate ETCO2 measurements, and reduces the difficulty of ventilation during transport. The type of advanced airway (ETT vs. SGA) probably does not matter.

Parenteral Access

Before the conversation surrounding epinephrine is to be had, we need to discuss parenteral access – intravenous (IV) vs. intraosseous (IO).

IOs are generally very easy to insert and are thus tempting. However, there is caution around considering IV and IO to be comparable in terms of effectiveness. In a secondary analysis of the ALPS study (Kudenchuk et al. 2016), the authors noted that patients who had antiarrhythmics administered by IV, had better survival than given by IO.

The caveat to all of this is the need to provide medications early to maximize effect. We need more studies to determine whether this is a true difference in routes, or a phenomenon created by the way the different routes are used during care. Currently, based on what we know, if you have IV access that should be your first choice, however if there’s no IV quickly, it’s probably best to jump to IO.

Epinephrine

In the 1960’s researchers induced dogs into cardiac arrest, and found that the dogs that received epinephrine lived, and those that did not died (Pearson. Am Heart J 1963). So 1mg was born as the standard of care for resuscitation. And it was this way for over 50 years until people really started to question the evidence (how much, how often, etc.) behind epinephrine use.

Physiologically, giving epinephrine makes sense, and we give it for its alpha properties (vasoconstriction) to improve coronary perfusion pressure. Epinephrine does have some unwanted beta stimulation (increased myocardial oxygen demand) as well. There is also some research to suggest that although epinephrine increases pressure in larger blood vessels that it may actually reduce blood flow in the cerebral microvasculature.

In 2018, a large randomized control trial (RCT) from the UK, the PARAMEDIC2 trial was published in the NEJM, comparing epinephrine vs. placebo in out-of-hospital cardiac arrest.

Perkins (2018) NEJM

While there was significant debate on the results of the trial the most accurate interpretation fo the results is that there was in increase in survival at discharge and 30-days but no difference in neurological outcomes (the study was not powered to look for this difference). There is now some good evidence that suggests that epinephrine improves survival to hospital discharge, but it is unclear if there is an improvement in neurological outcome.

We know that cardiac arrest interventions are time dependent and perhaps epinephrine is also time dependent. If you administer epinephrine late in a resuscitation it is likely the patient will not have a good outcome but if you administer epinephrine early on and obtain ROSC it is more likely the patient will have a good neurological outcome (Donnino 2014. BMJ). Similarly, the dose of epinephrine may also make a difference. Glover et al. found that survival decreased significantly with increased doses of epinephrine and that administration of more than 3 doses was associated with poor outcomes (Glover 2012. Resuscitation 83(11): 1324-30.).

The use of epinephrine may not be as straight forward as “yes” or “no” but impacted by multitude of factors such as timing, dosage, interval. There are many outstanding questions regarding epinephrine administration.

Antiarrhythmics

There is less evidence for the use of antiarrhythmics than epinephrine. The most significant RCT looking at antiarrhythmics is the ALPS study, comparing amiodarone, lidocaine, and placebo in out-of-hospital cardiac arrest. The ALPS study found no difference between any of the drugs and survival (Kudenchuk 2016. NEJM. 374: 1711-1722).

Similar to epinephrine a subgroup of patients from the ALPS study who were bystander witnessed had improved survival with antiarrhythmics (amiodarone or lidocaine) compared to placebo, suggesting that perhaps there is a time dependent effect and providing antiarrhythmics early on has an advantage.

Scene Times

“Load and Go” or “Stay and Play”? This is a patient level decision. The real question is, “Can the hospital provide treatment that you cannot?”. In the standard run of the mill cardiac arrest, the answer is to probably stay on scene and run the arrest. A 2020 North American study (part of the Resuscitation Outcomes Consortium) found that among patients experiencing out-of-hospital cardiac arrest, intra-arrest transport to hospital compared with continued on-scene resuscitation was associated with lower probability of survival to hospital discharge.

In pediatric out-of-hospital cardiac arrest, survival to hospital discharge has been shown to be highest (10.2%) with on-scene times of 10-35 minutes, compared to the >35 min. group (6.9%) and the <10 min. group (5.3%).
Grunau (2020) JAMA; Tijssen (2015) Resuscitation

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To summarize, high-quality BLS management of cardiac arrest is essential. This includes ensuring CPR and ventilation quality including the use of feedback devices and measuring and providing feedback of performance. Once the BLS stuff is taken care of, treatment/management should be dictated by the patient. This may or may not prioritize the airway.

Perhaps most important, is early access and early drug administration. The evidence points that IV access may be better than IO and that medications are still useful, especially early during the resuscitation.