Journal Club #2: Otten et al. Comparison of BVM Hand techniques... Ann Emerg Med 2013

[Brandon O]

Otten D, Liao MM, Wolken R, et al. Comparison of Bag-Valve-Mask Hand-Sealing Techniques in a Simulated Model. Ann Emerg Med. 2013 Aug 9. pii: S0196-0644(13)00693-8. doi: 10.1016/j.annemergmed.2013.07.014. [Epub ahead of print]

Everyone's encouraged to participate -- ask questions, share your thoughts, suggest considerations. As before, try to answer at least one of the questions below in your reply!

1. What's the question we're looking at? Why do we care in EMS?
   
2. What type of study was this? If observational, was it retrospective or prospective?
   
3. What is the PRIMARY outcome? (Was there more than one?) What were the SECONDARY outcomes? (Were there more than three?) Do we care about these outcomes?
   
4. Any reason to suspect bias? Conflicts of interest among the authors? Who sponsored the study?
   
5. Who was the study population (what were the inclusion/exclusion criteria)? 1. Is it suitable to answer the question? 2. Is this population relevant for us?
   
6. What was the comparison/control? Was it appropriate? If randomized, what was the allocation method, was it concealed, and were the groups initially similar? If observational, are there potential variables that were not controlled, and what effect might they have?
   
7. Is there any reason why control patients might have been treated differently after enrollment, and was this controlled? If not, what effect might it have?
   
8. Were there any losses/failures after enrollment, and if so, were they analyzed using intention-to-treat?
   
9. Were patients blinded? Providers? Evaluators of the gold standard? Statistical analysts?
   
10. How reliable was the gold standard? How long was study follow-up, and was this adequate? Was the study stopped early?
    
11. What are the results? Are they statistically significant? Clinically meaningful? Are they the same primary/secondary outcomes initially described? Are they plausible?
    
12. What are the results in terms of NNT (for therapy) or LR (for diagnostics/risk)? What were the harms? Were benefits greater than harms?
    
13. What were the authors' conclusions, and are they supported by the results?

 

[Brandon O]

I'll get things started...

* What's the question we're looking at? Why do we care in EMS?

Should we be using the one-handed "EC" technique we're usually taught, or is a two-handed technique better? If so, which method (the "double EC" or the "thumbs down"), and how much better?

* What type of study was this? If observational, was it retrospective or prospective?

A small, prospective trial using a convenience sample (i.e. whomever was around); providers were asked to hold a mask to a dummy using the different techniques and the results were measured. It was a partial cross-over -- both groups did one-handed first, but then tried both two-handed techniques in opposite orders.

 

[Christopher]

My bad, I just noticed this!

What is the PRIMARY outcome? (Was there more than one?) What were the SECONDARY outcomes? (Were there more than three?) Do we care about these outcomes?

Primary outcome(s): expired tidal volume, defined as percentage of total possible expired tidal volume during a 5-minute bout.

Secondary outcome(s): none.

Additional measurement(s): gender, education/profession, BVM experience, hand size (breadth, length), handedness, grip strength.

Do we care about these outcomes?

Yes and no. The outcome as defined provides a decent measure of the ability to deliver ventilations to a test lung in a manner comparable throughout all participants in this study. However, it would not necessarily be comparable between setups or studies.

Any reason to suspect bias? Conflicts of interest among the authors? Who sponsored the study?

No device itself is at play, no new medications are at play, instead the efficacy of three techniques are examined. Potentially bias could be introduced due to the design of the study, providing insight to the subjects as to the measured outcome. Some subjects who favor one technique over the other could potentially tip the scales in their techniques' favor.

Who was the study population (what were the inclusion/exclusion criteria)? 1. Is it suitable to answer the question? 2. Is this population relevant for us?

The study population was a convenience sample of, "current health care providers at Denver Health Medical Center, Denver, CO. Recruitment included respiratory therapists, medical students, resident physicians, attending physicians, critical care or emergency department registered nurses, and paramedics."

The only exclusionary criteria was the inability to physically perform the task.

This population is relevant as it includes pre-hospital providers, but it may not accurately reflect a general population of pre-hospital providers (e.g. in a 2008 study by Alexandrou et al of patient positions for intubation the three paramedics and one physician who was previous a paramedic ended up favoring a technique disliked by all other participants).

What was the comparison/control? Was it appropriate? If randomized, what was the allocation method, was it concealed, and were the groups initially similar? If observational, are there potential variables that were not controlled, and what effect might they have?

Comparison was 1-handed technique to each of the 2-handed techniques and then between the two 2-handed techniques. Due to the nature of the study, there is no way to blind the participants to the techniques in question. Randomized allocation simply determined which of the 2-handed techniques a person began with.

This has the possibility of introducing bias as participants could learn the outcome.

Were there any losses/failures after enrollment, and if so, were they analyzed using intention-to-treat?

All 52 participants completed the study.

Were patients blinded? Providers? Evaluators of the gold standard? Statistical analysts?

All participants were blinded to the outcome measure but not the techniques. However, due to the design of the study it seems feasible that the participants could guess the study outcomes.

What are the results? Are they statistically significant? Clinically meaningful? Are they the same primary/secondary outcomes initially described? Are they plausible?

The results found that a 2-handed BVM technique was superior w.r.t. the outcome measure as compared to a 1-handed BVM technique.

Comparison of the 2-handed techniques with each other was non-significant.

The outcomes discussed are the same as those measured.

These findings are plausible and consistent with prior studies.

What were the authors' conclusions, and are they supported by the results?

The authors conclude that a 2-handed BVM technique (either standard or modified) is superior to a 1-handed BVM technique w.r.t. to volume of delivered ventilations. This measure provides a reasonable surrogate for efficacy of ventilation.

Additionally, the authors concluded that the 2-handed techniques enable female providers to deliver similar ventilations to males. However, because of the small sample size, multivariate analysis was not completed so further inferences from the descriptive data were not made.

What's your take home message Christopher?

My biases have been enhanced and I will continue to preach the 2-handed, two-thumbs-down thenar eminence technique for BVM ventilation. My EMT students will continue to sigh whenever a BVM gets brought out. Dr. Reuben Strayer will rest easy knowing his technique survives another day.

 

[EpiEMS]

I know I'll continue to do two-handed BVM!

I'd love to see this done with a totally naive sample.

 

[Brandon O]

One of my favorite parts of this is the numbers. Although it's a small trial and we shouldn't hang our hats on the figures, still -- the median amount of expired air with the one-handed technique was only 31% of what they tried to squeeze in. Less than a third! No wonder we need such big bags; most of it's going anywhere but into the patient. "Experienced" providers were NOT any better, and female providers had a median of only 10% air vs 57% for males.

But it's cool... because with two hands, everybody got over 80%

 

[unleashedfury]

What I like about the study is it shows that there is no hat to hang on experience level.

Experience level did not change the outcome of the 2 handed technique

I am a firm believer in the two hand technique as individuals with small hands or women could have difficulty applying a firm seal. And your study proves that anyone regardless of anatomical features are capable of providing a good two handed seal with similar results.

now to get this practice to be applied amongst the healthcare field could prove difficult you still have the old schoolers who believe that the technique they use is best and they have been doing this way for years with no adverse effects.