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.
Andre Johnson says
What if the capnography number is not what the ABG CO2 is, How can this be useful. Also when intubating a patient for tube placement why would a capnography be better than a colorimetric
for EET placment
ACLS says
Typically the ETCo2 and PaCo2 should be relatively close in comparison. Here’s a good article that explains why there would be a difference between entitle CO2 and arterial CO2.
Understanding the Gap: The Difference Between Arterial and End Tidal CO2
Waveform capnography, can be used to monitor CPR effectiveness and it can also be used to monitor appropriate to placement. There are added benefits with waveform capnography.
Kind regards,
Jeff
Lila O'Mahony says
Any validated EtCO2 readings for pediatric resuscitation?
This comes up more often in our EMS community who routinely resuscitate adults and much less commonly infants/kids.
Thank you!
ACLS says
There is not any validated work with regard to pediatric resuscitation and end ETCO2.
To my knowledge, the only decent review showed no increased survival to hospital discharge with pediatric cardiac arrest even if the ETCO2 was maintained greater than 20 mmHg.
ETCO2 Review
Pediatric values would be treated just as adult values. Here are some major references with regard to ETCO2 monitoring and cardiac arrest in general
38. Falk JL, Rackow EC, Weil MH. End-tidal carbon dioxide concentration during cardiopulmonary resuscitation. N Engl J Med 1988;318:607-11.
39 Treveno RP, Bisera J, Weil MH, Rackow EC, Grundler WG. End-tidal CO2 as a guide to successful cardiopulmonary resuscitation. A preliminary report. Crit Care Med 1985;13:910-11.
40. Weil MH, Besera J, Trevino RP, Rackow EC. Cardiac output and end-tidal carbon dioxide. Crit Care Med 1985;13:907-9.
41. Sanders AB, Kern KB, Otto CW, Milander MM, Ewy GA. End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation. A prognostic indicator of survival. JAMA 1989;262:1347-51.
Kind regards,
Jeff
Angelo says
We recently ran a code and the patient had been worked on for about an hour before he came to us. EMS has shocked him 9 times for vfib and given him 7 doses of epi. He was unlikely to survive and actually became asystolic en route. He had an advanced airway placed in the periphery. During compressions in our ambulance bay I noted that despite no pulse and fixed +dilated pupils, during cpr his end tidal CO2 was 60! I couldn’t believe what I was seeing because 35-45 is considered rosc! What was going on here?!?!? I’m so confused. Were the compressions that good? Or did he have favourable anatomy that allowed for such great gas exchange? I’m having a hard time explaining it.
Any help would be great! 🙂
Thanks
ACLS says
My first gut feeling on this would be that the ETCO2 was in accurate for some reason. I’ve never seen numbers like that with a patient that was clearly deceased. There should be no gas exchange. I really don’t have any explanation. I’m sorry that I could not be of more help.
Kind regards,
Jeff
John Horne says
Was there a long pause without compressions or ventilations just before that reading?
Jeff H says
If you find I good answer to your question I would like to know myself. I have had the same situation. Once with ET tube confirmed placement, square wave form, proper depth on X-ray and over an hour of working the patient still getting CO2 readings in the 50’s. Ulstrasound at ED showed no heart movement with PEA on monitor. I have searched for an answer but haven’t found anything
Louis Sonstegard says
If patient does not have is a tracheal tube in place, with the microstream capnography is satisfactory to determine end-tidal CO2. Other words can I act on a 10 with microstream capnography? And can I reliably follow rosc if the microstream capnography increases from 35 – 45 mm HG.
ACLS says
Unfortunately, the cannula microstream capnography technology will not provide an accurate measurement of etco2 during cpr, and it should not be used in such cases. At this time, proper ETCO2 measurement during cpr can only be performed when an ET tube is in place.
Recently, a miniature in-line capnography device that includes a waveform has received FDA approval and could serve as an ideal device for measurement of EtCO2 by both BLS and ALS providers when ventilating apneic patients or assisting ventilations in patients with respiratory failure. This device will make it possible to monitor etco2 without an ET tube.
Kind regards,
Jeff
Rehana Tanweer says
ET CO 2 35-45 mmhg means that cellular activity is normal. If ET CO2 is less than 10 mmhg during the CPR , the waste is not being circulated to the lungs so it is a poor quality CPR.
Izzy says
Hello I would appreciate if you could explain how the number 10 on the end tidal CO2 came to be. I’ve always had my own theory. I split normal end tidal CO2 (35-45) which would be 40 and then multiplied it by 25%. The highest percentage of effectiveness of compressions during cardiac arrest. Thats how I came to the number 10. I don’t know if I am way off but either way I would love a clinical explanation how that number came to be. Thanks -Izzy
ACLS says
My assumption was that it is because less than 10 mmHg is a high indicator of poor outcomes. Greater than 10mmHg indicates minimal carbon dioxide metabolism in order to sustain life.
When patients have a ETCO2 less than 10 this indicates that normal cellular metabolism is not taking place. Without these normal metabolic functions, life is not sustainable.
I hope that helps. Please let me know if you have any other questions.
Kind regards,
Jeff
Matt says
Jeff,
Question: Will the ETCO2 only show during the ventilation parts (every 6 seconds), or during the whole cycle – including the compressions?
Thanks
ACLS says
A ETCO2 reading will always be visible, but the part that you will be looking at on the monitor for ROSC Will be on exhalation in between your bag ventilations. The exhalation phase is when the CO2 reading is accurate for monitoring ROSC. This will be the highest point on the waveform. The highest point on the waveform indicates peak exhalation.
Kind regards,
Jeff
DrGasPasser says
I am on the Code Committee at my hospital and am an anesthesiologist. I have been approached by multiple practitioners claiming that ETCO2 may be used to detect ROSC (no argument there, we have been using it similarly in low CO states and trauma for a very long time) and therefore having ETCO2 means you never have to stop chest compressions for rhythm checks. I argue that ETCO2 waveform would not be reliably and distinctly different during asystole/PEA versus pVT/VF. If your patient changed rhythm from asystole to pVF/VT (shockable rhythms) and you did not check a rhythm every two minutes, you would delay defibrillation. IS there a consensus regarding ETCO2 and the need for rhythm checks every two minutes as per the ACLS guidelines. Thank you
Jeff with admin. says
Within AHA there is a consensus that ETCO2 is the most accurate way to detect ROSC. With that said however, along with this consensus comes some difficulties and limitations.
First, the patient must be intubated in order to accurately measure ETCO2. Therefore ETCO2 monitoring would be restricted to intubated patients only.
Second, rhythm checks would still be necessary since ETCO2 would not differentiate between rhythms present but would only indicate when ROSC happens. As you stated, this would delay defibrillation in the case you are dealing with the ventricular fibrillation or pulseless ventricular tachycardia.
And third, so many facilities do not have the ETCO2 monitoring capability or do not have proper training with waveform capnography to make definitive guideline changes that eliminate rhythm/pulse checks.
Kind regards,
Jeff
endaz says
Etco2 above 10 during CPR and 35 to 40 for rosc . Once an advanced airway is in, is it still 10 as they have not yet achieved rosc.
Jeff with admin. says
As high-quality CPR continues, the ETCO2 should improve somewhat. For the first minute of CPR, it will probably be less than 12.5 mmHg. If high-quality CPR continues then the ETCO2 should rise to 12.5–25 mmHg in the second and third minutes.
Regardless of whether a advanced airway is in place, the goal for ETCO2 that indicates effective high-quality CPR is greater than 10 mmHg until ROSC is achieved.
Kind regards,
Jeff