Also, according to the AHA, continuous waveform capnography along with clinical assessment is the most reliable method of confirming and monitoring correct placement of an ET tube.
What is Waveform Capnography
Quantitative waveform capnography is the continuous, noninvasive measurement and graphical display of end-tidal carbon dioxide/ETCO2 (also called PetCO2). Capnography uses a sample chamber/sensor placed for optimum evaluation of expired CO2. The inhaled and exhaled carbon dioxide is graphically displayed as a waveform on the monitor along with its corresponding numerical measurement.
As an assessment tool during CPR, capnography can help the ACLS provider determine a number of things. It is a direct measurement of ventilation in the lungs, and it also indirectly measures metabolism and circulation. For example, a decrease in perfusion (cardiac output) will lower the delivery of carbon dioxide to the lungs. This will cause a decrease in the ETCO2 (end-tidal CO2), and this will be observable on the waveform as well as with the numerical measurement.
Normal ETCO2 in the adult patient should be 35-45 mmHg.
Two very practical uses of waveform capnography in CPR are: 1.) evaluating the effectiveness of chest compressions, and 2.) identification of ROSC. Evaluating the effectiveness of chest compressions is accomplished in the following manner: Measurement of a low ETCO2 value (< 10 mmHg) during CPR in an intubated patient would indicate that the quality of chest compressions needs improvement.
High quality chest compressions are achieved when the ETCO2 value is at least 10-20 mmHg.
When ROSC occurs, There will be a significant increase in the ETCO2. (35-45 mmHg) This increase represents a drastic improvement in blood flow (more CO2 being dumped in the lungs by the circulation) which indicates circulation.
For the intubated patient in cardiac arrest, quantitative waveform capnography is now considered the desired method for monitoring the quality of chest compressions and determining when the patient has a ROSC.
This video explains waveform capnography, it benefits, and various applications.
Joe Joe says
Hello, I try to keep this brief. The other day I was talking to a flight medic, when he stated that a low Co2 less than 10 is what you want in a cardiac arrest. I just want to know does he know something we dont.
Jeff with admin. says
The following is a quote directly from the AHA ACLS provider manual page 67:
“Persistently low petCO2 values less than 10 mmHG during CPR in intubated patients suggests that ROSC (return of spontaneous circulation) is unlikely.”
On the same page it says: “If the petCO2 is less than 10 mmHG during CPR, it is reasonable to try to improve chest compressions and vasopressor therapy.”
Either you misunderstood your friend or he does not understand end tidal CO2 monitoring during cardiac arrest.
Kind regards,
Jeff
steven ortiz says
….more better……!
Brittany says
What would a typical capnography readying be during cardiac arrest? such as the normal is 35 to 45. would it be much lower as in like 10 or 25 or would it be higher?
Jeff with admin. says
I will give a couple of answers for this question and there are different scenarios.
1. During cardiac arrest if the patient is not breathing or being ventilated, the capnography reading would be 0. (no CO2 is being exhaled from the lungs)
2. During cardiac arrest if the patient is receiving CPR (chest compressions and ventilation) that are not effective then you would have a reading < 10 mmHg. 3. During cardiac arrest if the patient is receiving CPR (chest compressions and ventilation) that is effective then you would hopefully see a reading between 10-20. One important note is that any break in chest compressions will significantly decrease end-tidal CO2 and compromise ROSC (return of spontaneous circulation). This is why it is so important to maintain effective chest compression and adequate ventilation. Note the chart at the top of page 69 in the AHA provider manual. It shows a nice graph of 5 minutes of CPR. Notice that it takes about 90 seconds of effective CPR to build arterial pressure enough to get the etCO2 above 10 and keep it there. I hope this helps. Kind regards, Jeff
Debyspen says
I work in community Er n we don’t have capnography! We only have co 2 detectors ! I wish this was mandatory
medic77 says
I’m surprised you don’t use it on a regular basis Deb. In upstate NY it is standard practice in pre-hospital and hospital as well I believe.
moemoeone says
I hate abbreviations what is ROSC I’m really feeling dumb
Jeff with admin. says
Return of spontaneous circulation
Mary Albert says
Isn’t this tool also used on non-intubated patients also? Please advise.
Jeff with admin. says
You are correct. Waveform capnography can be monitored on the non-intubated patient using a special type of nasal cannula with a ETCO2 monitor on it. However, for the purposes of ACLS, its primary function is to confirm placement of the ET tube and to monitor effectiveness of chest compressions and for ROSC. —Jeff
Dr.VIJESH JEYAKUMAR says
PRECISE & SIMPLE . THIS IS MORE THAN ENOUGH FOR A BEGINNER. THIS EXPLANATION WOULD HAVE BEEN EVEN MORE BETTER IF THE METHOD OF MEASUREMENT & A PICTORIAL REPRESENTATION WERE GIVEN.
andrea o connor says
I never fully understood the reason for being so careful with bicarb until now. Your explanation made it so simple to understand in a way that no one else has been able to do for me. thanks and by the way….i love this site annie
Gregorio says
Hola un poco más sobre la vía aérea.
Shaun Stamnes says
The Physio-Control LP-12 and LP-15 both have wave form EtCO2 on them as an option. They collect the samples through direct sampling on an ET tube adapter or as nasal prongs. They work very well.
Sandman says
Hi Jack and Chris.
I’m teaching life support courses and found out that our defibs. has no means of capturing PetCO2. Is there any other means to check the end tidal CO2 so as to be in line with the new standards of AHA?
regards.
Jeff with admin. says
They have portable EtCO2 units out there. They are stand alone. That would work just as well. I don’t know of any others that on the defibs or the portables. There is not way to extrapolate the EtCO2 that I know of.
Jeff
Male castillo says
Quisiera saber que forma tienen esas ondas
solymolj says
what is the normal value of ETCO2
Chris with admin. says
The normal Values for ETCO2 is 35-45mmHg
See the link below for details about waveform capnogrophy.
https://acls-algorithms.com/waveform-capnography
cmjack says
Hi Glenn,
Great question. First off, in states of metabolic acidosis, the body has an overabundance of H+ ions. Excess H+ ions react with Sodium Bicarbonate (NaHCO3), and the biproducts of this reaction are CO2 and H2O. If the patient has not been intubated and ventilated adequately, the CO2 that has been created will not be effectively removed. Elevated levels of PaCO2 blunt myocardial function and correlate with myocardial ischemia and decrease myocardial contractility.
Hence, it is best and most important to correct any source of respiratory acidosis prior to administration of NaHCO3. Some possible exceptions would be Cardiac arrest with suspected hyperkalemia, tricyclic antidepressant overdose, significant crush injury.
A blood gas would be most beneficial to verify the source of acidosis. Thank goodness for istat machines!
On a side note, 1) Excessive administration of NaHCO3 can shift the oxy-hemaglobin dissociation curve to the left, causing hemoglobin to hold onto oxygen and not give it off to the tissues. 2) Also, there is some evidence that administration of NaHCO3 can worsen coronary perfusion and impair cardiac contractility during cardiac arrest this may be due to the fact that NaHCO3 significantly reduces plasma ionized calcium. Several studies that I have reviewed demonstrated that NaHCO3 does not improve hemodynamics in critically ill, severely acedemic patients.
I hope this helps. Let me know if you have any other questions. I will be glad to help.
Blessings,
Chris
AL. says
CHRIS: A GREAT EXPLANATION AND SIMPLE TO FOLLOW. AB0UT 20-30 YEARS AGO, I USE TO SEE LOADS OF BICARB. BEING PUSHED ONTO THE PATIENT. THE EXPLANATION WAS THAT THE CODE HAD BEEN LONG, THE PATIENT MOST LIKELY IN A ACIDOTIC STATE AND WHAT DO WE HAVE TO LOOSE. BIG NICE CHANGES SINCE THEN.
AL.
Glenn Johnson says
Hello would you please explain why it is so important to have a pt intubated prior to given bi carb i am trying to understand the acid base balance.I know the pt gets acodotic during cardiac arrest, but is it to control resp. for the pt to blow off carbion dixiode to regulate resp please e mail me back to help me thanks Glenn Johnson