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Sunday, March 18, 2012
Sunday, April 3, 2011
Welcome
Welcome to CardiAction Detroit! CardiAction is a non-profit organization developed with the goal of improving the quality of CPR that is administered by both healthcare professionals and the general public to cardiac arrest patients in Detroit. This site highlights the most important aspects of CPR and gives some background physiology to explain the reasons why these steps are so critical. This information is a supplement to the 2010 Basic Life Support and Advanced Cardiac Life Support guidelines published by the American Heart Association.
There are very few medical emergencies as dramatic and time-sensitive as cardiac arrest, and there are few other opportunities as members of the medical community and Detroit at large to make such a meaningful impact on lives outside of the hospital. Quick action and good technique truly do make the difference between life and death.
This site is published as a blog in order to provide you the opportunity to comment, respond, or provide additional resources for other readers. Ideally, this space will serve as a resource for our community to refer healthcare professionals and interested members of our community to improve CPR, and your input will make that happen.
Thank you for visiting, come back often, and please share with your friends and colleagues.
There are very few medical emergencies as dramatic and time-sensitive as cardiac arrest, and there are few other opportunities as members of the medical community and Detroit at large to make such a meaningful impact on lives outside of the hospital. Quick action and good technique truly do make the difference between life and death.
This site is published as a blog in order to provide you the opportunity to comment, respond, or provide additional resources for other readers. Ideally, this space will serve as a resource for our community to refer healthcare professionals and interested members of our community to improve CPR, and your input will make that happen.
Thank you for visiting, come back often, and please share with your friends and colleagues.
The Importance of Good CPR
The heart is a pump. Its job is to draw blood from the circulation into its chambers, and then eject that blood back out. It doesn’t think or make decisions, just slows down or speeds up based on the instruction of the brain. It is an amazing piece of machinery that begins in the eighth week of life and never takes a break…..ever. But sometimes the pump fails. There are dozens of causes that lead to its failure, but the when the heart stops, so does the body, and no matter why it stops, if the pump doesn’t get re-started, life ends.
The heart receives its oxygen supply from the coronary arteries, the very first vessels that branch from the aorta as it leaves the left ventricle. The coronaries receive their blood during the diastolic, or relaxation, phase of a heartbeat, and the blood that courses through them is rich in oxygen. Other muscles in the body take a small percentage of the oxygen out of the blood as it passes through the capillaries, but the heart is greedy and takes nearly all of the oxygen out of the blood, so there isn’t much reserve. When the heart stops beating, the muscles don’t get that valuable oxygen, and they aren’t able to contract or do any work, so they can’t provide any new blood. The pump runs out of fuel.
Cardio-pulmonary resuscitation aims to fix the broken pump. By compressing the chest, the idea is to move blood around the body to make sure tissues get oxygen, which buys time until the heart can be restarted. Even more important, however, is CPR which moves un-oxygenated blood out of the coronary arteries and bring oxygenated blood back in to supply the hungry cardiac tissue. In effect, CPR primes the pump, giving it the valuable fuel that it needs to resume its tireless beating.
The earlier proper chest compressions are started, the sooner that oxygen-rich blood gets to the heart and other fragile tissues in the body. Keeping that blood circulating keeps the patient alive. It also moves the ACLS medications given to restart the heart from the veins to the heart tissue where it can actually do its job.
Great CPR saves lives, so let’s looks at how we can make good CPR great.
The heart receives its oxygen supply from the coronary arteries, the very first vessels that branch from the aorta as it leaves the left ventricle. The coronaries receive their blood during the diastolic, or relaxation, phase of a heartbeat, and the blood that courses through them is rich in oxygen. Other muscles in the body take a small percentage of the oxygen out of the blood as it passes through the capillaries, but the heart is greedy and takes nearly all of the oxygen out of the blood, so there isn’t much reserve. When the heart stops beating, the muscles don’t get that valuable oxygen, and they aren’t able to contract or do any work, so they can’t provide any new blood. The pump runs out of fuel.
Cardio-pulmonary resuscitation aims to fix the broken pump. By compressing the chest, the idea is to move blood around the body to make sure tissues get oxygen, which buys time until the heart can be restarted. Even more important, however, is CPR which moves un-oxygenated blood out of the coronary arteries and bring oxygenated blood back in to supply the hungry cardiac tissue. In effect, CPR primes the pump, giving it the valuable fuel that it needs to resume its tireless beating.
The earlier proper chest compressions are started, the sooner that oxygen-rich blood gets to the heart and other fragile tissues in the body. Keeping that blood circulating keeps the patient alive. It also moves the ACLS medications given to restart the heart from the veins to the heart tissue where it can actually do its job.
Great CPR saves lives, so let’s looks at how we can make good CPR great.
Don't Look, Listen, or Feel
Classically, the first step to CPR after making sure the scene is safe was “look, listen, and feel”. The idea was that by using three of the five senses, rescuers would be able to determine whether a patient needed resuscitation. With the new guidelines from the American Heart Association, “look, listen, and feel” is out the window. Now, rescuers are asked to feel for a pulse for a maximum of ten seconds, and if no pulse is palpated after ten seconds, CPR should be started.
Get Fit
Chest compressions are hard work. Anyone can do it, but you have to give yourself the advantage. Be sure to position yourself OVER the patient, not next to them. If that means you have to climb on the stretcher and straddle them, do it. If the bed is too high, ask for a step stool. Lock your arms, and push with your core.
This image illustrates proper CPR positioning and form. Thank you to the El Paso Fire Department in El Paso, TX for sharing.
If chest compressions are being performed correctly, two minutes of CPR should make an Olympian tired. When a patient arrests in the hospital, an appropriate code allows three to four healthcare professionals to rotate through two minutes of compressions, followed by rest. In the field, this isn’t possible, and we recognize this. Nonetheless, your compressions are the only thing keeping this person alive (and EMS already performs many super-human feats that we in the hospital could never replicate – ie carry a 400 lb patient UP basement stairs).
If chest compressions are being performed correctly, two minutes of CPR should make an Olympian tired. When a patient arrests in the hospital, an appropriate code allows three to four healthcare professionals to rotate through two minutes of compressions, followed by rest. In the field, this isn’t possible, and we recognize this. Nonetheless, your compressions are the only thing keeping this person alive (and EMS already performs many super-human feats that we in the hospital could never replicate – ie carry a 400 lb patient UP basement stairs).
Between A Rescue and A Hard Place
The first task in performing good CPR is positioning the patient correctly. CPR will not be effective if the patient is not lying flat on a hard surface, whether that is placing a board beneath the patient or placing them on the floor. If a patient is lying in a bed at home, roll them onto a backboard or place them on the floor. If they are on a stretcher or hospital bed, roll them onto one of the half-length CPR boards typically kept on the side of the crash cart, or remove the headboard from the bed and pass it beneath the patient.
Compressions
Cardiac output = stroke volume x heart rate
A high cardiac output means that the organs that need blood are getting perfused, so improving the cardiac output in a patient in arrest (output = zero) is the ultimate goal of CPR. We can’t magically change output, but we have control over the heart rate by changing the number of compressions per minute, and we change stroke volume by adjusting the depth of chest compressions.
Cardiac output = stroke volume x heart rate
The limiting factor in changing the stroke volume is that the heart is protected from direct access by the chest wall. Instead of just pumping the heart, we have to pump the entire chest. The chest is compressed, and the pressure in the thorax ejects blood from the ventricle. The ribcage provides recoil, and the negative pressure produced by the recoil pulls blood from the peripheral circulation into the atrium and ventricles so that the next compression actually has blood to eject back into circulation. Not pushing deep enough means stroke volume is decreased, and that lowers the cardiac output. However, deep compressions break ribs and that means a loss of recoil. Contrary to popular belief, breaking someone’s ribs does NOT mean you are doing good CPR.
The balance of adequate stroke volume and appropriate recoil in a good chest compression depresses the sternum 2 inches, or 1/3 the depth of the chest. Ribs may break, and if it’s because you are compressing the chest to the correct depth, that’s ok, but don’t make it your goal.
There are lots of devices coming onto the market to measure chest compressions. Small sensors ride between patients' chests and rescuers' hands and give continuous feedback. Many hospital systems are even looking to review this data after-the-fact to evaluate the quality of CPR.
Cardiac output = stroke volume x heart rate
If increasing the stroke volume is so difficult with CPR, the only other option we have to improve cardiac output is to maintain a high heart rate. In CPR, this means lots of compressions, 100 compressions, each minute. Slower than 100, and cardiac output drops to a point where CPR is not doing any good. Compressions faster than 100, and the heart does not have enough time to refill with blood before the next compression.
A high cardiac output means that the organs that need blood are getting perfused, so improving the cardiac output in a patient in arrest (output = zero) is the ultimate goal of CPR. We can’t magically change output, but we have control over the heart rate by changing the number of compressions per minute, and we change stroke volume by adjusting the depth of chest compressions.
Cardiac output = stroke volume x heart rate
The limiting factor in changing the stroke volume is that the heart is protected from direct access by the chest wall. Instead of just pumping the heart, we have to pump the entire chest. The chest is compressed, and the pressure in the thorax ejects blood from the ventricle. The ribcage provides recoil, and the negative pressure produced by the recoil pulls blood from the peripheral circulation into the atrium and ventricles so that the next compression actually has blood to eject back into circulation. Not pushing deep enough means stroke volume is decreased, and that lowers the cardiac output. However, deep compressions break ribs and that means a loss of recoil. Contrary to popular belief, breaking someone’s ribs does NOT mean you are doing good CPR.
The balance of adequate stroke volume and appropriate recoil in a good chest compression depresses the sternum 2 inches, or 1/3 the depth of the chest. Ribs may break, and if it’s because you are compressing the chest to the correct depth, that’s ok, but don’t make it your goal.
There are lots of devices coming onto the market to measure chest compressions. Small sensors ride between patients' chests and rescuers' hands and give continuous feedback. Many hospital systems are even looking to review this data after-the-fact to evaluate the quality of CPR.
Cardiac output = stroke volume x heart rate
If increasing the stroke volume is so difficult with CPR, the only other option we have to improve cardiac output is to maintain a high heart rate. In CPR, this means lots of compressions, 100 compressions, each minute. Slower than 100, and cardiac output drops to a point where CPR is not doing any good. Compressions faster than 100, and the heart does not have enough time to refill with blood before the next compression.
Stay On The Chest
The American Heart Association recommendation is 5 seconds off-chest-time, MAX. That means there should never be more than five seconds that a patient in cardiopulmonary arrest is not getting chest compressions, and it's one of the biggest mistakes in performing good CPR. The good news? It's really easy to fix - stay on the chest!
This graph illustrates the idea that in order for blood to be supplied to the body, a pressure-head must be built up. In fact, the first ten to fifteen compressions after every break in CPR works solely to get the blood moving from a standstill, and it is only after those first compressions get the blood moving does CPR actually provide perfusing blood flow to the organs. Every break in CPR leads to a sudden drop of pressure back to zero, and then the next 15 compressions build the pressure-head back up again. Limiting off-chest time is clearly paramount to survival.
This means when you are switching CPR performers, the new provider has their hands over yours and you are providing compressions together until you pull away from the patient’s chest. This also means that you should be performing chest compressions while the defibrillation paddles are being charged, and even while they are being placed on the chest. Only when the charger shouts, “clear!” should you stop compressions and step back.
Interesting side-note: A recently published article showed that bi-phasic defibrillators with sticky pads (rather than paddles) do not require the person performing chest compressions to stop during defibrillation. Attempt at your own risk.
This graph illustrates the idea that in order for blood to be supplied to the body, a pressure-head must be built up. In fact, the first ten to fifteen compressions after every break in CPR works solely to get the blood moving from a standstill, and it is only after those first compressions get the blood moving does CPR actually provide perfusing blood flow to the organs. Every break in CPR leads to a sudden drop of pressure back to zero, and then the next 15 compressions build the pressure-head back up again. Limiting off-chest time is clearly paramount to survival.
This means when you are switching CPR performers, the new provider has their hands over yours and you are providing compressions together until you pull away from the patient’s chest. This also means that you should be performing chest compressions while the defibrillation paddles are being charged, and even while they are being placed on the chest. Only when the charger shouts, “clear!” should you stop compressions and step back.
Interesting side-note: A recently published article showed that bi-phasic defibrillators with sticky pads (rather than paddles) do not require the person performing chest compressions to stop during defibrillation. Attempt at your own risk.
What About Breathing?
With all this emphasis on chest compressions and limiting off-chest time to 5 seconds, when do we help the patient breath?
New CPR guidelines tell lay population to ignore the breathing altogether. The main reason for this is that the airway part of CPR is the most difficult (jaw-thrust, chin-lift, pinch nose, give two breaths), and the reality is no one wants to make-out with a passed-out stranger anyway!
Healthcare professionals are a different story – you have the skills to bag-valve mask, place supra-glottic airways, and intubate – but the principle remains the same. Circulation is the most important action in a cardiac arrest patient. Start with chest compressions, and unless the patient is intubated, keep doing the 30:2 ratio (compressions:breaths) that you remember from before.
Once an airway is secured, asynchronous ventilation takes over; one breath is now delivered by whoever is manning the airway every 8 seconds irrespective of the chest compressions.
This is so important that the American Heart Association has changed the order of approach to arrest patients. No longer is it “A-B-C, Airway, breathing, circulation,” but now “C-A-B, Circulation, Airway, Breathing”. There is evidence to suggest that appropriate depths of chest compressions move enough air on their own that the blood flowing through the vessels with your constant CPR is oxygenated enough to support the tissues for quite some time!
New CPR guidelines tell lay population to ignore the breathing altogether. The main reason for this is that the airway part of CPR is the most difficult (jaw-thrust, chin-lift, pinch nose, give two breaths), and the reality is no one wants to make-out with a passed-out stranger anyway!
Healthcare professionals are a different story – you have the skills to bag-valve mask, place supra-glottic airways, and intubate – but the principle remains the same. Circulation is the most important action in a cardiac arrest patient. Start with chest compressions, and unless the patient is intubated, keep doing the 30:2 ratio (compressions:breaths) that you remember from before.
Once an airway is secured, asynchronous ventilation takes over; one breath is now delivered by whoever is manning the airway every 8 seconds irrespective of the chest compressions.
This is so important that the American Heart Association has changed the order of approach to arrest patients. No longer is it “A-B-C, Airway, breathing, circulation,” but now “C-A-B, Circulation, Airway, Breathing”. There is evidence to suggest that appropriate depths of chest compressions move enough air on their own that the blood flowing through the vessels with your constant CPR is oxygenated enough to support the tissues for quite some time!
The Trouble With Ventilation
Every time a breath is given to the patient, the intra-thoracic pressure in the chest increases. This increase in intra-thoracic pressure halts the return flow of blood to the heart. For this reason, even if a patient is intubated in the resuscitation bay in an ED, one breath every ten to 20 seconds would be more than adequate to support life until return of spontaneous circulation.
Breaths every two to five seconds are DETRIMENTAL to patients who do not have spontaneous circulation. One breath every two seconds means there is positive pressure in the chest (and no return blood) half the time CPR is being performed! Providing ventilations requires a calm provider who is consciously providing breaths to the patient MUCH less often than with any other type of patient.
It is also imperative that rescue breaths are given during the recoil phase of chest compressions so the person providing oxygen is not working against the person performing chest compressions.
Interesting side-note: In the hospital setting, some physicians attach a ventilator to the bag-valve mask and set the machine to deliver one breath every 15 seconds, eliminating the human temptation to over-breathe during CPR. Over-ventilating a patient is enough to negate all your hard work in CPR, but it's easy to prevent if you keep it in mind.
Breaths every two to five seconds are DETRIMENTAL to patients who do not have spontaneous circulation. One breath every two seconds means there is positive pressure in the chest (and no return blood) half the time CPR is being performed! Providing ventilations requires a calm provider who is consciously providing breaths to the patient MUCH less often than with any other type of patient.
It is also imperative that rescue breaths are given during the recoil phase of chest compressions so the person providing oxygen is not working against the person performing chest compressions.
Interesting side-note: In the hospital setting, some physicians attach a ventilator to the bag-valve mask and set the machine to deliver one breath every 15 seconds, eliminating the human temptation to over-breathe during CPR. Over-ventilating a patient is enough to negate all your hard work in CPR, but it's easy to prevent if you keep it in mind.
End-tidal CO2
Quantitative End-tidal CO2 has quickly become the standard of care for monitoring the efficiency of CPR. By monitoring the CO2 coming from the lungs, we can not only confirm placement of an endotracheal tube after intubation, but using new technology with real-time electronic monitoring we can determine the levels of CO2 with each breath.
With each chest compression, some volume of air will also be expelled from the lungs. Initially this air contains residual CO2 from the lungs, but those levels will disappear to zero quickly. In an arrest patient, the end-tidal CO2 will remain at zero. However, if blood is moving through the lungs (no matter how slow), gas exchange from the capillaries to the alveoli will still occur. Good chest compressions WILL move enough blood that oxygen will still be delivered to the tissues, and CO2 will be brought to the lungs to be exhaled and measured.
Using this knowledge, the quality of CPR can now be monitored – if adequate chest compressions are circulating blood it will be reflected by end-tidal CO2. If the person performing CPR gets tired, or someone is doing bad compressions, ETCO2 will decrease.
ETCO2 has also eliminated the need to stop chest compressions in order to check a pulse. ETCO2 is lower with CPR than in patients with spontaneous circulation. Now, instead of stopping CPR to feel the carotids for a subjective pulse, monitoring ETCO2 will show a significant jump when spontaneous circulation returns (illustrated in the image below), and a pulse has likely returned. If ETCO2 is being monitored during CPR and a sustained increase in CO2 by 15 mmHg is noted, return of spontaneous circulation has likely occurred.
Even after a jump in ETCO2 is noted, compressions should be continued for a full minute before halting chest compressions to check for a pulse.
This image illustrates ETCO2 monitoring during CPR, with a sharp, sustained increase with ROSC.
By the numbers:
Bad CPR = ETCO2 <15
Good CPR = ETCO2 >15
ROSC = ETCO2 increases suddenly by 15
With each chest compression, some volume of air will also be expelled from the lungs. Initially this air contains residual CO2 from the lungs, but those levels will disappear to zero quickly. In an arrest patient, the end-tidal CO2 will remain at zero. However, if blood is moving through the lungs (no matter how slow), gas exchange from the capillaries to the alveoli will still occur. Good chest compressions WILL move enough blood that oxygen will still be delivered to the tissues, and CO2 will be brought to the lungs to be exhaled and measured.
Using this knowledge, the quality of CPR can now be monitored – if adequate chest compressions are circulating blood it will be reflected by end-tidal CO2. If the person performing CPR gets tired, or someone is doing bad compressions, ETCO2 will decrease.
ETCO2 has also eliminated the need to stop chest compressions in order to check a pulse. ETCO2 is lower with CPR than in patients with spontaneous circulation. Now, instead of stopping CPR to feel the carotids for a subjective pulse, monitoring ETCO2 will show a significant jump when spontaneous circulation returns (illustrated in the image below), and a pulse has likely returned. If ETCO2 is being monitored during CPR and a sustained increase in CO2 by 15 mmHg is noted, return of spontaneous circulation has likely occurred.
Even after a jump in ETCO2 is noted, compressions should be continued for a full minute before halting chest compressions to check for a pulse.
By the numbers:
Bad CPR = ETCO2 <15
Good CPR = ETCO2 >15
ROSC = ETCO2 increases suddenly by 15
What You Should Expect At The Hospital
As we have mentioned before, CPR is hard work and chest compressions should be exhausting. With this in mind, EMS providers should not be expected to continue chest compressions AND unload patients from an ambulance with only a two-man crew. More appropriately, medical staff (whether physicians, nurses, techs, or students) should meet the ambulance at the hospital doors and immediately take over chest compressions while EMS unloads the patient (and takes a breath!). It is the responsibility of EMS providers to inform the hospital that a patient is being brought with CPR in progress, last known vital signs and time, and an estimated time of arrival; it is the responsibility of the doctors to ensure someone is waiting for the patient to arrive.
Overwhelming evidence supports the use of therapeutic hypothermia for patients with cardiac arrest who undergo return of spontaneous circulation after CPR, and you should be able to expect this for your patients as well. Hypothermia has become the standard of care for patients post-cardiac arrest; please see our entire page dedicated to describing the process, physiology, and research behind therapeutic cooling.
Overwhelming evidence supports the use of therapeutic hypothermia for patients with cardiac arrest who undergo return of spontaneous circulation after CPR, and you should be able to expect this for your patients as well. Hypothermia has become the standard of care for patients post-cardiac arrest; please see our entire page dedicated to describing the process, physiology, and research behind therapeutic cooling.
Pearls
The most important person in a code is the one doing chest compressions.
A thready pulse is not a reason to stop CPR! The American Heart Association suggests CPR until a strong, bounding pulse can be easily palpated.
Sometimes during resuscitation, the patient’s heart will transiently slip from an un-shockable rhythm to a shockable rhythm, and suddenly back to an un-shockable rhythm. In order to catch this shockable rhythm, the person manning the defibrillator should keep the paddles/pads charged throughout the process, and should re-charge the paddles/pads immediately after shocking in order to be ready.
Asystolic patients who receive electrical shocks do WORSE than those who do not. Remember, asystole is not a shockable rhythm.
Calcium and sodium bicarbonate are at the bottom of the ventricular fibrillation algorithm, but maybe they shouldn’t be? Consider giving both early in your resuscitation.
A thready pulse is not a reason to stop CPR! The American Heart Association suggests CPR until a strong, bounding pulse can be easily palpated.
Sometimes during resuscitation, the patient’s heart will transiently slip from an un-shockable rhythm to a shockable rhythm, and suddenly back to an un-shockable rhythm. In order to catch this shockable rhythm, the person manning the defibrillator should keep the paddles/pads charged throughout the process, and should re-charge the paddles/pads immediately after shocking in order to be ready.
Asystolic patients who receive electrical shocks do WORSE than those who do not. Remember, asystole is not a shockable rhythm.
Calcium and sodium bicarbonate are at the bottom of the ventricular fibrillation algorithm, but maybe they shouldn’t be? Consider giving both early in your resuscitation.
American Heart Association 2010 ACLS Guidelines
In 2010, the American Heart Association unveiled new guidelines for CPR, as well as new algorithms.
Here is the 2010 algorithm for the general public:
The 2010 algorithm for healthcare providers:
Link to the full text in the American Heart Association Journal, Circulation http://circ.ahajournals.org/content/vol122/18_suppl_3/.
Here is the 2010 algorithm for the general public:
The 2010 algorithm for healthcare providers:
Link to the full text in the American Heart Association Journal, Circulation http://circ.ahajournals.org/content/vol122/18_suppl_3/.
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