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.

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

7 comments:

  1. I think most anaesthetists would say that a supraglottic airway device does not provide a complete barrier against aspiration. Also not all SGAs are the same; how would these devices perform in cold patients (in relation to seal pressures etc.)? The obsession with initial ventilations in drowning, and ILS recommendations on in-water resuscitation based on weak evidence is concerning. As this study shows, rescue times are prolonged, and as we know, chest compressions cannot be performed in the water. We should be advising lifeguards/water rescue professionals to get patients back to shore as soon as possible, then start CPR. The notion of using syringes to inflate cuffs of airway devices, or use a bag-mask as a single operator (as opposed to how it should be used with one person holding the mask and another squeezing the bag) and achieve a good seal/adequate tidal volume is absurd, even more so in moving water or surf. I can just see LMAs inserted upside down/back to front. What about the effect of cold water on the rescuer's dexterity?? Good on these guys for an interesting study, which conclusively proves what a bad idea it is to use adjuncts in the water, as opposed to mouth-to-mouth whilst awaiting for a rescue craft/helicopter, which is probably okay (but taught by very few lifesaving agencies) versus just swimming them back to shore

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  2. Agreed. A point to note is this trial "consisted of towing a resuscitation manikin over a 100 meter distance in an inland lake". It would be interesting to see this study replicated in surf conditions. I would suggest it is virtually impossible to perform adequate ventilations on a patient without experiencing aspiration in a surf zone environment. I believe we need to be teaching lifeguards to return a patient to land without delay.

    This is reinforced by the recent study profiled here, which reveals of 336 cases of cardiac arrest following drowning (70.5% of which occurred in the ocean) there were no survivors when EMS response time was greater than 12 minutes.

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  3. If the heart has stopped there isn't much point in ventilations so we in GB teach '5 initial breaths and the back to shore as fast as possible for CPR'.

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  4. I don't disagree with either of the above posters nor the study. My question is: do we need a set procedure? There are so many variables to consider. If the submersion has been a matter of seconds in relatively (relative to the rescuers ability) and if fins, a rescue can or board is used, a couple of breaths maybe all that's needed. Without these breaths the hypoxia is increased while the victim is moved to shore. Make the same situation a large victim in pounding surf with little equipment and just getting the victim in will be a struggle.
    We need these kinds of studies! They may not be perfect and the results may leave more questions than answers, but they move us forward.

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  5. Great thoughts Bob. As anyone who has been involved in open water lifesaving knows, the best practice rescue and resuscitation procedures don't always survive the wave impact zone. Performing rescues in a surf environment is so often part art and part science. Which is why these sorts of randomized trials are so important - and as you rightly say, continue to push us forward with an evidence based approach.

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  6. i'm sorry if i misunderstand this, but i cant see how a patient would survive this, there seems to be too much time being taken. Why mess about? an IRB, is the best and fastest way to rescue the patient and commence CPR. Please forgive me if i have this wrong, i understand that rescue boats are not always available, but one person rescuing? wouldn't the rescuer be better use, focusing on getting the patient to shore?

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  7. Interesting to note the lack of both mouth to nose IWR and IWR with a pocket mask.

    The former is the the preferred method of IWR in the UK, and the latter is often issued to LG's and having used it in a diving environment, if provides a good seal. It is also a lot easier to swim out with than some of the other options! However, it also is unlikely to stay on in surf!

    My next question is whether the the LG's was wearing fins. I think this should be pushed as a priority for open water LG's, not only quicker to reach a casualty but also quicker to return and easier to perform IWR.

    As open water LG's we need to train for worse possible scenario - i.e. there is not always a powered craft available. Let's not forget the 3 minute target regarding lack of O2 and the brain.

    On the whole I think the key thing is not to over-think the rescue but focus on having well-trained and experienced LG's who can think for themselves and make decisions supported by researched evidence. This way they have options. There are far too many variables to be able to make open water protocols cut and dried.

    Provide the necessary tool box - equipment, knowledge, training and experience, and then do not second guess the actions of the rescuer, post-rescue.

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