Date: April 22nd, 2016
Guest Skeptic: Jay Loosley. Jay is a Registered Nurse, Paramedic and Research Assistant. He was a Professor at Fanshawe College but is currently the Superintendent of Education for Middlesex-London Emergency Medical Services.
Case: A 43 male patient calls with chest pain from 14th floor of a downtown high-rise apartment building. After the 911 dispatcher gets the address and details of the chest pain, the patient stops responding and the dispatcher can hear no voice. The paramedic response time is 4 minutes with lights and sirens to the apartment. The paramedics enter the controlled access area and buzz the apartment number. Of course the patient doesn’t answer because he is vital signs absent. The paramedics look on the control panel for a building superintendent, and attempt to buzz them. Of course he isn’t in his apartment at the time, so it goes to voicemail. The paramedics start picking random names on the list to buzz. “Hi this is the paramedics, could you please let us in?” Click, they hang up. They try another name, and another name until someone buzzes them in. Upon entering the lobby, the first elevator that opens won’t fit the stretcher, so they have to send it up, and wait for the second one. After it comes down, they take it to the 14th floor, where of course the apartment door is locked. One medic goes back down to the lobby to get the superintendent’s number and after a few minutes, they arrive at the 14th floor to open the patient’s door and allow us access to the building. Ten to fifteen minutes after the arrival of the Paramedics, they gain access and meet their patient, a 43-year-old male, vital signs absent, with the phone in his hand.
Background: Recent data from the AHA estimates about 350,000 EMS-assessed OHCA happen in the United States each year. The median age is 65 years. Half of these arrests are witnessed (bystander 38% and EMS provider 12%) with the other half being unwitnessed. The majority of these cardiac arrests happen at a home or residence (70%). Of those EMS-treated patients with OHCA about ¼ have an initial shockable rhythm. Survival to discharge from hospital for adults with OHCA assessed by EMS is around 6% (AHA Statistical Update 2016).
The American Heart Association came out with updated CPR & ECC Guidelines in 2015 that included its “Chain-of-Survival”. There are five steps in the Chain-of-Survival for OHCA:
- Step One – Recognition and activation of the emergency response system
- Step Two – Immediate high-quality CPR
- Step Three – Rapid defibrillation
- Step Four – Basic and advanced emergency medical services
- Step Five – Advanced life support and post arrest care
Clinical Question: Is there an association between floor of patient contact and survival of out of hospital cardiac arrest?
Reference: Drennan et al. Out-of-hospital cardiac arrest in high-rise buildings: delays to patient care and effect on survival. CMAJ 2016.
- Population: Adults with OHCA of not obvious cause at private locations
- Excluded: Children, witnessed arrests by first responders, traumatic arrests or with another obvious cause, or in a public location
- Intervention (prognostic factor): On or above the 3rd floor
- Comparison: Below the 3rd floor
- Primary Outcome: Survival to hospital discharge
- Secondary Outcomes: Subgroup analyses
Author’s Conclusions: “In high-rise buildings, the survival rate after out-of-hospital cardiac arrest was lower for patients residing on higher floors. Interventions aimed at shortening response times to treatment of cardiac arrest in high-rise buildings may increase survival.”
- Did the study address a clearly focused issue? Yes
- Did the authors use an appropriate method to answer their question? Yes. You can not randomize people for their OHCA.
- Was the cohort recruited in an acceptable way? Yes. All consecutively treated adults with OHCA of no obvious cause at a private location.
- Was the exposure accurately measured to minimize bias? Yes.
- Was the outcome accurately measured to minimize bias? Yes. Dead or alive is fairly easy to accurately measure.
- Have the authors identified all important confounding factors? No. We will discuss this in detail in the talk nerdy section.
- Was the follow up of subjects complete enough? Yes.
- How precise are the results/is the estimate of risk? Point estimates were provided for OR with 95% confidence intervals.
- Do you believe the results? Yes.
- Can the results be applied to the local population? Yes. In urban areas with high-rise buildings.
- Do the results of this study fit with other available evidence? Yes. While no other studies have specifically investigated this question of elevation, we do know that delays to CPR and defibrillation for OHCA decrease chance of survival.
Key Results: 7,842 cases of OHCA met inclusion. 5,998 (76.5%) were below the 3rd floor and 1,844 (23.5%) were on the 3rd floor or higher.
There were baseline differences between the two groups. Those on or above the 3rd floor were more likely to be female; less often witnessed; took EMS longer to reach; and were less likely to have a shockable rhythm.
Overall survival to hospital discharge was 3.8% regardless of what floor you were on.
- Primary Outcome: Lower survival was associated with 3rd floor or above OR 0.70 (95% CI 0.50–0.99)
Survival below 3rd floor vs. 3rd floor or above:
4.2% vs. 2.6% p=0.0002
- Subgroup Analysis: A subgroup analysis was done based on building type. They found 2,363 cases of OHCA in adults living in apartment buildings. Survival was 35/667 (5.2%) for those cases below a 3rd floor apartment and 46/1,696 (2.7%) for those cases above the 3rd floor apartment.
- Time to Patient Contact: They measured the time of arrival of 911-initiated first responders on scene to actual patient contact and found a difference of almost two minutes longer for patients on the higher floors (4.9min vs. 3.0min; p=0.01)
- Variables Associated with Lower Survival to Hospital Discharge (Adjusted):
- Older Age OR 0.96 (95% CI 0.95–o.97)
- Male Sex OR 0.72 (95% CI 0.54–0.95)
- Longer 911 Response Time OR 0.86 (95% CI 0.79–0.92)
- Variables Associated with Higher Survival to Hospital Discharge (Adjusted):
- Initial Shockable Rhythm OR 10.68 (95% CI 7.98–14.29)
- Witnessed Arrest OR 2.93 (95% CI 2.16–3.98)
- Other Results:
- Survival rate above the 16th floor was 0.9% (2/216).
- Survival rate was zero percent for those above the 25th floor (0/30).
This was an interesting study asking about delays in care of OHCA in unique way. Once again we reached out to the lead author Ian Drennan who agreed to come on the show.
Ian is a PhD candidate at Rescu, St. Michael’s Hospital and the Institute of Medical Science at the University of Toronto. He works as an advanced care paramedic with York Region Paramedic Services and is an instructor with Sunnybrook Centre for Pre-hospital Medicine. Ian also holds faculty positions in the health sciences department at both Georgian College and Centennial College.
Listen to the podcast to hear Jay’s full responses to our questions:
- Observational Trial: The biggest limitation to this study is that it was an observational trial. In this type of study design only associations can be demonstrated, not causation.
- You are absolutely right, as with all observational research designs there are inherent limitations that are associated with this type of study design. Although we found an association between higher floors and decreased survival after controlling for some well-known predictors of survival, we are unable to determine a cause and effect relationship with observational research. This is because we are unable to account for all possible confounding variables that may affect the relationship between our variables and outcome of interest.
- I would not think that there is anything physically about the higher floors that all of a sudden you survive less if you cross over the third floor so there must be other confounders, beyond what we controlled for in our analysis, that are at least partially responsible for the result.
- I think the reasons why this association was seen need to be further investigated, but it is interesting that there was an association in our data between having a cardiac arrest on higher floors and poor outcome.
- Associations Beyond Elevation: You found other associations besides elevation with increasing or decreasing chance of survival.
- Yes, as part of the analysis we examined the effect of the floor of the arrest and survival while controlling for some other known predictors of survival such as age, initial cardiac rhythm, witness status, bystander CPR, and 911 response time.
- What we found was that after controlling for these variables, older age, male sex and longer 911 response times were all independently associated with worse outcomes.
- We also found that initial shockable cardiac rhythms and bystander-witnessed cardiac arrests were associated with higher rates of survival. All of these factors are typically found to be associated with patient outcomes after out-of-hospital cardiac arrest so none of these results were surprising.
- CPR Rates: What was your overall rate of CPR in this study?
- Overall we had about 35% bystander CPR rate, however rate of AED use was <1%.
- You did not find a difference in survival with bystander CPR? Was that just a no difference between above and below the 3rd floor or no difference in CPR in general for survival? (OR 1.07, 95% CI 0.83–1.39)?
- No that is correct. The rate of bystander CPR was actually the same on higher and lower floors. When we looked at bystander CPR on survival, the unadjusted analysis was significant but when we adjusted for other variables there was a non-significant effect.
- Now I wouldn’t suggest based on this one study then that bystander CPR is not important. My interpretation is that first survivors and non-survivors both had relatively decent rates of bystander CPR (45% vs 35%), second it appears in our adjusted analysis that much of the effect on survival is run by the variables initial rhythm, and witness status, which is common in OHCA research, and that these can sometimes overpower some of the other variables.
- Overall Survival to Hospital Discharge: You found the overall survival to hospital discharge for adult OHCA was 3.8%. This is less than the 5% found in the OPALS study. Why do you think there was a difference?
- Good question. So a few reasons why the survival was slightly lower in our study. First, our population was different than OPALS as we required a specific population to answer our research question; specifically private residences (which are known to have lower survival than public cardiac arrests) and we excluded EMS witnessed cases (again a group known to have higher survival than non-EMS witnessed cases).
- Second, some of the other factors that are associated with higher survival such as witnessed arrests and initial shockable rhythm were lower in our study as well.
- Patient Oriented Outcome: You reported survival to discharge but not survival to discharge in good neurologic condition. Wouldn’t that be a very important patient oriented outcome?
- Correct, so we only reported on survival to hospital discharge (yes/no) and did not specifically look at neurological outcomes of our patients at hospital discharge.
- Patients not only want to survive but they want to be neurologically intact. If the increase in survival to hospital discharge was just to be institutionalized in a long-term facility with poor neurologic function it would not be considered by most to be a positive outcome.
- I can tell you from our research that the vast majority of patients who survive do so with a good neurologic status, but this would be an interesting and important outcome to look at as well.
Comment on author’s conclusion compared to SGEM Conclusion: We generally agree with the authors’ conclusions.
SGEM Bottom Line: We need to find ways to maximize bystander CPR, improve access to AEDs and eliminate barriers for first responders.
Case Resolution: Paramedics arrive to the patient, CPR is started, defibrillator pads are applied and the first rhythm analysis shows a fine ventricular fibrillation, which is shocked once at 200 joules. An intravenous line is started, 1mg of epinephrine is given, and the next rhythm check is asystole. The patient is intubated, more epinephrine is given, and the patient has an end tidal CO2 that has dropped to 10. A call to the physician is made, a consult takes place, and the patient is pronounced dead at the scene
Clinically Application: Listen to the podcast for Ian’s full response.
- Maximize CPR (Bystander)
- Access to AEDs (Place in Elevators)
- Minimize Delays for 911- Responders (Universal Keys)
What do I tell my patient? The patient is dead Ken. However, on the way out, the neighbor says; “what took you so long to get up here? I saw your ambulance parked outside long before you came up here. What were you doing?” A short discussion takes place regarding what the paramedics were doing, and how they were trying to gain access, but simply could not get into the building. The building superintendent over hears the discussion, and now we are working with the city to create a bylaw for Paramedic access into buildings.
Keener Kontest: Last weeks winner was Crystal McLeod an Emergency Department nurse from Hanover, Ontario. She knew the Heart Score was first published in 2008.
Listen to the podcast this week for the keener question. If you think you know the answer then email TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will win a cool skeptical prize.