Waveform Capnography
Quantitative Waveform Capnography
The 2010 AHA Guidelines for ACLS now recommend using quantitative waveform capnography in intubated patients during CPR. Waveform capnography allows providers to monitor CPR quality, optimize chest compressions, and detect ROSC (return of spontaneous circulation) during chest compressions.
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 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 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 quality of chest compressions and determining when the patient has a ROSC.
This 8 minute video explains waveform capnography, it benefits, and various applications.
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
Hola un poco más sobre la vía aérea.
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.
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.
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
Quisiera saber que forma tienen esas ondas
what is the normal value of ETCO2
The normal Values for ETCO2 is 35-45mmHg
See the link below for details about waveform capnogrophy.
http://acls-algorithms.com/waveform-capnography
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
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