Gastric distention, BVM, CPR Ratios

[jjdjld1]

Hi all,

Have a small query that i thought i would run past everyone here. I've started noticing lately that a few EMS providers have been ventilating a non-intubated PT continously (via BVM/Ambubag and OPA) and ignoring the 30/2 CPR ratio. So in otherwords they are ventilating continously while chest compressions are being performed on a PT that has no patent airway. It was my understanding that this would cause severe gastric distention and increase the risk of aspiration. I was always taught that a PT without a patent airway gets a 30/2 ratio, and chest compressions need to be paused before each ventilation.

What are your thoughts on this? I apologise in advance for a boring question.

[PCP]

It's not a boring question at all. What causes the gastric distention and please if I am wrong anybody feel free to correct me, as I am fairly new medic. My understanding is gastric distention is caused by when someone is using the BVM and is pushing too fast and too hard and not letting the bag on the BVM to fill back up with oxygen before ventilating again . You want to be just giving enough air by pocket mask or BVM to make the chest rise, if you give too much air it will just go straight into the abd and start to cause the gastric distention. I am not sure how long it takes or how much air needs to be exposed to the abd. before this starts to happen.( Time to do some research tonight for myself) You are correct that gastric distention does increase the risk of aspiration and that is why the person at the head needs to be careful when ventilating a patien and watch for the signs of the distension.

I know in my OFA level course that I just had recert, they taught us to ventilate the pt. every 5 seconds while doing continous chest compresions, but in my paramedic program we did the 30/2 standard and that is what I use.

When a paramedic inserts a OPA that is keep the tongue from falling back into the throat and occluding the airway which then would deem as a patient not having a patent airway because the tongue is blocking the airway passage, but once the OPA is incerted and in place the patient is now deemed as having a patent airway. This is because the OPA is allowing as a device that as mentioned keeps the tongue from falling back and occluding the airway and allows for an air passage and for draining of any vomit which may occlude the airway deeming the airway not pantent do to the occluding vomit chunks or blood.

Hope I was able to answer you question for you and if I missed anything or made any mistakes in my answer anybody feel free to correct me as I do not want to be leading someone down the wrong path!

[jjdjld1]

Hey PCP,

Thanks for your response. My question was more along the lines of whether or not continuous positive pressure ventilation should occur while chest compressions are being performed in a pt that has no advanced airway (because of the potential of causing gastric distention). Or should compressions be stopped momentarily while ventilations are being done and then continue afterwards? In other words, in a CPR situation, with no advanced airway, would you stop every 30 compressions to allow your partner to ventilate or carry on pumping the chest anyway.

[PCP]

hey sorry about that my friend. guess I kinda went off on a different path. I would say yes they should be stopping compressions to give the two ventilations. Now that being said that is based on my training through the Heart and Stroke foundation. I am not sure where you are from and what your protocol is down there. I would talk to someone in your area and confirm what is expected in a CPR situation.

I find it very confussing at times, as I was shown one way on how to do CPR and it is alway 30 compressions to 2 ventilations and then I take my OFA training again and they are telling me to give a breath once every 5 seconds while your partner is still doing compressions. Another thing I just learned through the organization I work for is when the AED is charging to deliver a shock, we are to be doing chest compressions during the charging portion. But in school and through the Heart and Stroke Foundation we were told not to touch the pt. while the AED is charging..grrr why can't they make the same rules for everybody!

[Kiwiology]

Oxygenation and ventilation are not the same thing. Blindly squeezing the bag is not the way to go, think about each breath.

Squeeze the bag and in your mind say "release, release, release" and then squeeze the bag again.

Chest compressions should never be paused, well thats obviously not possible, so as little as possible and not for ventilation.

[Happiness]

The Rules just changed to NOT to stop compression until your AED is analyzing or going to shock. PCP you have to follow the rules of your organization.

There is a forum on the new rules but I was unable to find it.

[DwayneEMTP]

Though I know not a direct answer to your question, perhaps it will give you a bit of information explaining the 'why' of the answers you've already been given.

Also, though it's relatively easy to find research showing that PPV during CPR causes issues, I was unable to find any studies that show it to be a benefit in that instance. (Though was terribly committed to the task.) Has anyone heard of recent studies that show a benefit of PPV in an arrest?

Edit: I would think that PPV during compressions would increase the likelihood of Abd distention, but that's intuitive only. Though I have run across information that says that it takes very little pressure, surprisingly little, during PPV to cause distention.

http://www.dshs.stat...entilatory2.pdf

(Words in Italics indicate paragraph breaks created by me for ease of reading.)

"Purpose of review

In recent years, it has become increasingly apparent that

resuscitative ventilatory procedures, classically thought to

be life saving, may have profound detrimental effects.

Recent findings

Most assisted breathing techniques during resuscitation

involve the provision of intermittent positive pressure

ventilation to inflate lung zones for erythrocyte

oxygenation and clearance of carbon dioxide.

A growing number of studies involving low-flow states, however,

have demonstrated that provision of overzealous (or even

'normal') ventilatory rates with intermittent positive

pressure ventilation can significantly diminish both

systemic and coronary circulation, most likely through

inhibition of venous return.

Recent laboratory studies of hemorrhage have shown not only a direct detrimental

impact of each positive pressure ventilation breath on

coronary perfusion, but also how dramatic improvements

in blood flow can be achieved, without loss of

oxygenation, by delivering breaths infrequently during

such low-flow states. Likewise, in cardiac arrest models,

studies have shown that interrupting chest compressions,

even to provide breaths, can be extremely deleterious by

abruptly (and continually) lowering the aortic pressure

head to the coronary arteries, thus impairing restoration of

spontaneous circulation.

Even with endotracheal intubation and uninterrupted chest compressions,

frequent positive pressure ventilation still inhibits

circulation during cardiopulmonary resuscitation. Despite

directed training, paramedics (and other rescuers) have

been shown to still excessively ventilate during cardiac

arrest resuscitations. (Bold added by me)

Summary

Ventilation can have profound detrimental hemodynamic

effects in low-flow states, exacerbating the circulatory

compromise. This underappreciated confounding variable

may be one of the reasons many clinical trials of

resuscitative interventions have failed despite dramatic

successes in the laboratory."

Hope this helps man...great question..

Dwayne

Edited November 23, 2010 by DwayneEMTP

[Happiness]

The reason (explained to me)for the changes with ventilations in CPR is mostly to make easier for the lay person (public)to do CPR. They panic and by not doing the vents they can concentrate on chest compressions.

If you look at chest compression and the heart the same as an old fashion water pump you will see the following. When you start pumping on the old water pump it takes a few pumps to get the water flowing nicely and when you stop pumping it stops instantly. Then you start pumping again it take again a few pumps to get it flowing nicely again. It is the same with the heart if you stop pumping to assit with vents you are going to have to reprime the heart. The object of CPR is to keep the blood flowing as consistanly as possible.

When you are doing chest compressions you are creating enough force to make the lungs both inhale and exhale enough 02 to sustain life until you are able to administer life saving drugs or get your pt to a higher level of care.

Now that is not to say if you have help not to use the BVM but it is not the priority that it use to be.

Also in the public world generally (unless your a wacker)you are not carring any pocket masks or other devices that protect you from diseases.

[jjdjld1]

Thanks to everyone for your response. It puts things into perspective for me.

[tniuqs]

Greetings:

Hmm: the the 30/2 ratio is primarily for one "person CPR" but when there are minimum 2 practised individual, for example on a CODE TEAM in a hospital its quite a different thing the breath is interposed, YES shocking 5 to 1. Some research is indicating breath on the down stroke as opposed to "interposed" on upstroke is a higher success rate in outcomes. The intent of increasing the rate was "in theory" in people to increase and maintain higher pulsatile inter-thorasic pressures for a longer time period.

Forward blood flow /perfusion improves on average at the 14 to 16 th compression confirmed by Dopplar ultrasound studies in dogs. In 2 geographical areas in "out of hospital arrest" ie Vancouver BC and Seattle WA. there is an improvement with "cardiac saves" of up to 3% higher. In hospital cardiac saves are closer to 25 % in a study I participated University of Alberta that is just "cardiac save" to admission of ICU door to qualify.

Discharge to door is abysmal, quite frankly.

The no "breathing" CPR is exactly what most believe, lay people have a higher tenancy to step forward and try CPR without having to swap spit. Is that going to improve out of Hospital Arrests and TO-DOOR discharge ? I dunno .. and to the best of my knowledge has yet to be proven. I have a very difficult time believing that in-hospital or out-of-hospital arrests and NO Breathing Part for professionals (well that dog aint goin to hunt)

What we ARE seeing as a "trend" in protocols to "call them" dead earlier ... end tirade.

Though I know not a direct answer to your question, perhaps it will give you a bit of information explaining the 'why' of the answers you've already been given.

Also, though it's relatively easy to find research showing that PPV during CPR causes issues, I was unable to find any studies that show it to be a benefit in that instance. (Though was terribly committed to the task.) Has anyone heard of recent studies that show a benefit of PPV in an arrest?

Edit: I would think that PPV during compressions would increase the likelihood of Abd distention, but that's intuitive only. Though I have run across information that says that it takes very little pressure, surprisingly little, during PPV to cause distention.

<snip for brevity><edit for quotes> we have to keep Dwayne happy. te he.

Even with endotracheal intubation and uninterrupted chest compressions, frequent positive pressure ventilation still inhibits circulation during cardiopulmonary resuscitation.Despite directed training, paramedics (and other rescuers)have been shown to still excessively ventilate during cardiac arrest resuscitations. (Bold added by me)then screwed up by ME !

Summary

Ventilation can have profound detrimental hemodynamic effects in low-flow states, exacerbating the circulatory compromise. This underappreciated confounding variable may be one of the reasons many clinical trials of resuscitative interventions have failed despite dramatic successes in the laboratory."

Hope this helps man...great question..

Dwayne

Edited November 24, 2010 by tniuqs