Friday, February 22, 2013

Efficacy of ventilation and ventilation adjuncts during in-water-resuscitation

Efficacy of ventilation and ventilation adjuncts during in-water-resuscitation
Winkler BE, et al
Resuscitation, 2013

This was a randomized trial performed to evaluate the effectiveness of in-water resuscitation using different airway adjuncts.  This study has many weaknesses, but overall it is always exciting to see randomized trials being conducted within the open water lifesaving community.  Here is a synopsis of the study and its findings:

  • Study design
    • 19 lifeguards participated
    • Each performed 4 rescues in randomized order
      • No ventilations
      • Ventilation with mouth-to-mouth
      • Ventilation with bag valve mask
      • Ventilation with laryngeal tube (supraglottic device)
    • Each rescue was 100 meters
      • Manikin with measurement capabilities used
      • Ventilation performed every 10 seconds
  •  Measurements
    •  Rescue Time: from time of obtaining manikin to crossing finish line
    • Number of manikin submersions
    • Tidal volume and minute volume
    • Aspirated lung fluid in manikin
    • Subjective difficulty per rescuer
  • Results
    • Rescue times longer when ventilations performed
    • More submersions occurred when ventilations performed
    • Increased aspiration with mouth-to-mouth and bag-valve mask
    • Highest tidal volumes with laryngeal mask
      • Lowest with bag-valve
      • Laryngeal mask had stable tidal volumes
      • Adequate minute ventilations with mouth-to-mouth and bag-valve
 As stated before, what I like about this study was it was a fairly nicely designed and standardized look at in water resuscitation.  One weakness of the study is that it only deals with the time between contact with the victim and reaching land.  What it doesn't account for is the difficulty of reaching the patient with airway adjuncts (i.e. getting a bag valve mask out to the patient).  Another weakness was the use of manikins, which can't properly simulate a human's airway or evolving lung compliance due to aspiration, but this is likely the only study design possible.  The idea of using a supraglottic device is enticing since it gives adequate minute ventilations and would theoretically provide a barrier against aspiration, but I do question the feasibility of carrying a device and a bag valve mask to deliver ventilations during a rescue.

Winkler BE, et al. Efficacy of ventilation and ventilation adjuncts during in-water-resuscitation–a randomized cross-over trial. Resuscitation; 2013.

Wednesday, February 6, 2013

Drowning related out-of-hospital cardiac arrests: characteristics and outcomes.

Drowning related out-of-hospital cardiac arrests: Characteristics and outcomes
Authors: Dyson K, Morgans A, Bray J, Matthews B, Smith K
Journal: Resuscitation, January 2013

This article is a retrospective review of data from the Victorian Cardiac Arrest Registry (VACAR), which aimed to answer the following questions:

  • Of those in cardiac arrest following drowning, what is the survival to hospital rate?
  • Of those in cardiac arrest following drowning, what is the survival to discharge rate?
  • What are some factors which determine these rates?
A total of 336 cases were analyzed, 77% of each involved patients < 18 years of age. The following are important findings:
  • 70.5% occurred in the ocean
  • 17.9% were witnessed
    • These individuals were more likely to receive bystander CPR
    • No significant difference in outcome directly related to bystander CPR
  • EMS resuscitation attempted in 48%
    • Only 8% of these survived to discharge
    • Poor survival for those who did not achieve return of spontaneous circulation with EMS
    • No survivors when EMS response time > 12 min
    • Upon arrival of EMS, majority of patients in PEA arrest of asystole
      • PEA: 20% survival to discharge
      • V fib: 30% survival to discharge
      • Asystole: 3% survival to discharge
This study has the following limitations
  • Performed in single region
  • Retrospective (although introduction stated "prospective")
  • Did not include data on lifeguard involvement, especially in cases of delayed EMS arrival
All in all I was very excited to see this study come out.  It is the type of study I would love to see done more in the US, as It gives Emergency Medicine professionals some objective data to base clinical prognosis on.  Unfortunately is does show an overall dismal outcome for those experiencing cardiac arrest due to drowning.  Further study should aim to include major interventions which may affect outcome and neurological outcome at discharge.