Compressions only

[firetender]

Could someone please link me to the best study available documenting the efficacy of compressions only (and at what rate) and/or a study that best establishes the optimum ratio of Compressions to breaths.

Thanks!

 

[mycrofft]

2010 edition of CIRCULATION announcing the standards...

http://circ.ahajournals.org/content/122/18_suppl_3.toc

Hope that helps, just a hipshot. See messages

 

[firetender]

AHA guidelines still call for interposing breaths. I recall hearing about studies showing that persistent compressions well done at the rate of 100/minute with all focus on them and no attention to breaths are what works.

Can't find it/them

 

[46Young]

I read this in one of the recent trade mags - IIRC, do continuous compressions, and deliver a quick breath of approx 300 cc's every tenth compression during recoil, and even beginning to deliver the breath just before recoil occurs, to take advantage of neg. pressure. I can't remember what this is called, though.

 

[Medic Tim]

Cardiocerebral Resuscitation or CCR.

google or pubmed it and there are numerous studies that show it improves survival to discharge in most pts.

 

[mycrofft]

Curmudgeonly sidebar:

A. The type of "code" most likely to survive and revive is due to airway embarrassment.

B. In unconscious victims, and especially if you did not see them before they went down, the only way to know if their issue is a blocked airway is to attempt to ventilate.

1. The only differences raised by doing rounds of compressions and interposed attempted inflations are to check the airway after a round of compressions and attempt to sweep out blockages if seen.

"Hands only" means no "round" and no "check". If the airway is the primary problem and can be cleared very promptly you have one case with a significanty better outlook than if treated like all the others. Might even sit up and cough at you.

One possible change (2015 is coming around) in the "unconscious choking" or "unwitnessed man down" patients: in the "compress-check-sweep if indicated-attempt inflation" scenario, maybe do that about five minutes, then settle down to basic CPR either with or without inflations because anoxia has done its work. Or, maybe not.

 

[Tigger]

I read this in one of the recent trade mags - IIRC, do continuous compressions, and deliver a quick breath of approx 300 cc's every tenth compression during recoil, and even beginning to deliver the breath just before recoil occurs, to take advantage of neg. pressure. I can't remember what this is called, though.

The JEMS article was about upstroke ventilation.

 

[mycrofft]

AHA guidelines still call for interposing breaths. I recall hearing about studies showing that persistent compressions well done at the rate of 100/minute with all focus on them and no attention to breaths are what works.

Can't find it/them

ARC still teaches breaths for CPRO (CPR for professional responders) and hands-only as an option for laypersons (but it is not on the basic layperson video we use as canon, it is in the "bonus material" I think).

 

[mycrofft]

300 cc of ventilation?

The tracheao-bronchial "tree" is 10 cubic inches.
300 CC =18.3071232 cubic inches.

So the volume for gas exchange potentially reaching alveolar tissue (assuming total exhalation of the prior breath) is 8 1/3 cubic inches, about the volume of two decks of standard playing cards (4X2X1 inches).
No danger of hyperinflation there unless the exhalations are extremely poor (COPD?).

 

[GoldcrossEMTbasic]

Could someone please link me to the best study available documenting the efficacy of compressions only (and at what rate) and/or a study that best establishes the optimum ratio of Compressions to breaths.

Thanks!

"Push Fast Push Hard!"

 

[46Young]

The JEMS article was about upstroke ventilation.

Yep, that's it! Here's the link for everyone else:

http://www.jems.com/article/patient-care/using-upstroke-ventilation-optimize-coro-0

 

[Handsome Robb]

I read this in one of the recent trade mags - IIRC, do continuous compressions, and deliver a quick breath of approx 300 cc's every tenth compression during recoil, and even beginning to deliver the breath just before recoil occurs, to take advantage of neg. pressure. I can't remember what this is called, though.

Now that could be interesting

 

[mycrofft]

I wonder if passive high flow O2 (not pressurized) during hands-only CPR would make a difference?

 

[MonkeyArrow]

I wonder if passive high flow O2 (not pressurized) during hands-only CPR would make a difference?

I suppose that if the airway is open, the lungs would be able to passively take in some O2 through diffusion. How efficient it would be, not only in diffusing, but also in the gas exchange and distribution is the real question? Are you thinking about this as an alternative to PPV during CPR or as a means between CCR.

Here's this advocating no PPV for the first few mins. on scene:

Initial airway management is delayed until a second rescuer is available and is initially limited to placement of an oral-pharyngeal airway and administration of oxygen by non-rebreather mask. Insertion of an invasive airway and assisted ventilation are not performed until either return of spontaneous circulation or after three cycles of chest compressions, analysis and, when needed, shock. Most who have ROSC are intubated prior to transportation.

From: http://www.emsworld.com/article/10321029/cardiocerebral-resuscitation?page=2

 

[OnceAnEMT]

Here's this advocating no PPV for the first few mins. on scene:

I guess I am confused by this. I was under the impression that "hands only" was for non-trained bystanders who didn't feel comfortable providing PPV via rescue breaths. Yes it is more effective than nothing, and certainly more effective than only rescue breaths, but what is the negative to having a controlled airway while doing CPR, even at the beginning?

From what I'm getting here, a medic would withhold intubating, and anything else airway related, until after a cycle of compressions only. Am I collecting that correctly?

 

[NomadicMedic]

Yes. Intubation has moved far down the arrest algorithm.

 

[OnceAnEMT]

Yes. Intubation has moved far down the arrest algorithm.

...Huh. What were they teaching us What's the reason behind that? Didn't see it in this thread. Is it hindering rhythm analysis? or is it just not useful enough to take up the initial time?

 

[MonkeyArrow]

...Huh. What were they teaching us What's the reason behind that? Didn't see it in this thread. Is it hindering rhythm analysis? or is it just not useful enough to take up the initial time?

Its just not useful for the time it takes up. Per the article I cited in my last quote, if it is witnessed, the blood can still be oxygenated for up to 15 minutes after arrest reducing the need for immediate ventilations. Couple that with the heart's and brain's need for oxygenated blood and the amount of time it takes vs the relative reward that early on vs the failure rates, they found it better to just keep pumping. It takes too much time away from pumping, which is what keeps your survival rates high, for marginally effective results, at best.

On an another note, I wonder if someone is coming up with a way to non-invasively cross-clamp the aorta. I know in thoracotomies, that is what they to reduce unnecessary blood loss and only direct blood to the heart and brain, so I wonder if that can be looked at for SCA as a means of preventing neurological compromise.

 

[OnceAnEMT]

Its just not useful for the time it takes up. Per the article I cited in my last quote, if it is witnessed, the blood can still be oxygenated for up to 15 minutes after arrest reducing the need for immediate ventilations. Couple that with the heart's and brain's need for oxygenated blood and the amount of time it takes vs the relative reward that early on vs the failure rates, they found it better to just keep pumping. It takes too much time away from pumping, which is what keeps your survival rates high, for marginally effective results, at best.

Ok, so its not so much that intubation/any airway management interferes with equipment or procedure, it just doesn't win in the cost-benefit analysis of a witnessed MI. Makes sense. Now, bring out the whats ifs. Lets say there is a fire crew of 4 already on scene and doing compressions. After getting a monitor and pads and IO all on board, then you'd do airway? (Sorry, I'm a Basic, but love knowing what's going on at the higher level)

 

[Handsome Robb]

Ok, so its not so much that intubation/any airway management interferes with equipment or procedure, it just doesn't win in the cost-benefit analysis of a witnessed MI. Makes sense. Now, bring out the whats ifs. Lets say there is a fire crew of 4 already on scene and doing compressions. After getting a monitor and pads and IO all on board, then you'd do airway? (Sorry, I'm a Basic, but love knowing what's going on at the higher level)

Even with multiple people on scene airway is further down the algorithm depending on the etiology of the arrest. If it's respiratory in nature we're going to start trying to correct the hypoxia that was the cause of the arrest whereas if it's caused by something else that needs to be corrected first, to put it very simply.

Positive pressure ventilation increases intrathoracic pressure which reduces blood return to the heart which reduces ventricular filling which reduces cardiac output. So ventilating a patient can actually clause your compressions to be less effective than they would be when using passive oxygenation techniques.

Also, witnessed MI isn't the right vocabulary, witnessed cardiac arrest is what you're looking for. MI doesn't equal cardiac arrest.