Monday, November 4, 2019

Bystander-initiated conventional vs compression-only cardiopulmonary resuscitation and outcomes after out-of-hospital cardiac arrest due to drowning.

Title: Bystander-initiated conventional vs compression-only cardiopulmonary resuscitation and outcomes after out-of-hospital cardiac arrest due to drowning.
Authors: Fukuda, et al.
Journal: Resuscitation, Article in press (Nov 2019)

This article sought to answer the question of whether compression only CPR or conventional CPR (with rescue breaths) is better for improving survival in cardiac arrest due to drowning. This is obviously a very difficult topic to study given the overall quality of this kind of data, but the authors of this study did their best using a large national registry.

This study is important for a few reasons:

  1. This is a very important question with big education and treatment implications
  2. Misinterpreting the data from this specific paper can easily lead to incorrect assumptions regarding the treatment of the average drowning patient
Study design
  • Retrospective analysis with propensity matching
  • Inclusion
    • Out of hospital cardiac arrest (OHCA) due to drowning 
    • Received bystander CPR (with or without breaths)
  • Cohort
    • 5121 patients with OHCA due to drowning and bystander CPR
      • 928 conventional CPR
      • 4153 compression only CPR
      • 48.5% male
      • Median age 79 years
    • Propensity matched 928 in to conventional and compression only CPR groups
Results

  • 90% unwitnessed and asystole
  • No differences in favorable outcome. one month survival, and pre-hospital ROSC
Discussion

On the surface, this article would seem to suggest that there is no difference in survival benefit between compression-only CPR and CPR with breaths. These results go against our knowledge and teachings that drowning is defined by hypoxemia and that the goal of treatment should be its reversal. For this reason, evidence-based guidelines call for the inclusion of breaths in the CPR algorithm for drowning, despite the constant push for bystander compression-only CPR for cardiac arrest of cardiac origin.

As with any study like this, it is very important to understand WHO you are studying before you apply the results generally. In most studies done on drowning, the majority of patients are 1-4 years of age, or around there. In this study, 81% of patients were above 65; this is a very unusual and skewed drowning cohort. In Japan, multiple studies have found a higher rate of elderly drownings, especially while bathing which may explain these results. This issue with this is the high probability that many of these deaths were actually cardiac in nature and just happened to occur in water. Also, given the fact that 90% were witnessed and were found to be in asystole, the outcome can be expected to be dismal no matter what.

Even when looking at the younger age groups (more common for drowning), the small numbers and wide confidence intervals (without significance) don't reveal any useful conclusions.

Conclusions

While the authors did meet their goals of the paper, the unusually old study cohort makes it so the results of this paper can't be generalized to the average drowning patient. Researchers, educators, and public health officials should use caution when applying these results to practice and education.


Reference:

Fukuda T, Ohashi-Fukuda N, Hayashida K, Kondo Y, Kukita I. Bystander-initiated conventional vs compression-only cardiopulmonary resuscitation and outcomes after out-of-hospital cardiac arrest due to drowning. Resuscitation. 2019 Aug 22.