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Capnography vs. Pulse Oximetry as EMS Tool


Ridryder 911

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Capnography vs. Pulse Oximetry as EMS Tool

http://www.merginet.com/index.cfm?pg=airway&fn=capnog

By Bryan E. Bledsoe, DO, FACEP

February 2006, MERGINET—I am now of the opinion that continuous waveform capnography is a much better EMS tool than pulse oximetry. It took some convincing. After discussing capnography at length with my good friends Sal Silvistri, MD, FACEP in Orlando, Fla. and Ed Racht, MD, in Austin, Texas, it became clear how important this tool is. A study in the October issue of Annals of Emergency Medicine further reinforced this belief. These researchers confirmed what many of us felt to be correct— that end-tidal carbon dioxide (PetCO2) readings correlated with the partial pressure of carbon dioxide (PCO2) in arterial blood gas measurements.

In a prospective cohort of 39 acutely ill asthmatics, researchers compared arterial blood gas readings to capnography. Because of the severity of their asthma, these patients underwent arterial blood gas analysis (not for the purpose of the study). The a priori limits of agreement were ± 5 mm Hg between the PetCO2 and the PCO2. The PetCO2 was recorded during exhalation at the exact same time arterial blood pulsated into the blood gas syringe. The mean difference between the PetCO2 from capnography and the PCO2 from arterial blood gas measurement was 1 mm HG (95% CI: -0.1 to 2.0 mm Hg). The median was 0 mm Hg. Of the 39 patients in the study group, 37 (95 percent) fell within the a priori limits of agreement.

They concluded that in acute asthmatic exacerbations in adults, the PetCO2 correlated with PCO2 levels. While additional validation of these findings is needed, the overall findings look very promising.

Reference

Corbo J, Bijur P, Lahn M, Gallagher EJ. “Concordance Between Capnography and Arterial Blood Gas Measurements of Carbon Dioxide in Acute Asthma.” Annals of Emergency Medicine. 2005; 46:323-327.

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We personally started using EtC02 monitoring more than the usual assessment. We now include for aid in diagnoses of DKA, treatment modalities of using beta[sub:38f0f1ef8b]1[/sub:38f0f1ef8b] etc.. With PROPER education this device is very informative as an ADJUNCT tool in diagnostics. I personally believe it as well to know the ventilation as well as oxygenation perfusion (v/Q) . There are several web sites (www.capnography.com) etc.. I highly recommend Dr. Krauss material. He is a professor emergency medicine at Harvard and has done intense research in capnography in EMS.

Be safe,

R/ R 911

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We are still waiting for capnography to be mandated, so that we can afford to purchase the equipment. What I have learned about it, makes me wonder why it hasn't gotten into more places sooner. One department I know of spent a significant amount of money for waveform capnography, then didn't bother to educate their personnel on how to use it, other than a full arrest. :roll:

Using etCO[sub:8787094a65]2[/sub:8787094a65], along with a pulse oximeter, will almost allow you to predict what treatment is needed, and how they will respond. If I could only have one, I would go with the capnograph, but we already have the pulse ox, so we might as well use them.

One question for you Rid. Did you mean beta-2 agents? I don't recall capnography relaying as much information about the beta-1's, but I could be mistaken.

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Capnography has its advantages, when relating to correct endotracheal tube placement and the obvious monitoring of the lungs [condition and efficiency], and yes rather simple to use, however this analytical instrument is not a robotic doctor, it will not tell you how to treat patients. Moreover, it may provide the medical team with more sustainable respiratory indictors, to help maintain successful respirations, I am sure my Philips MRX has this capability, although I have never used it, but may give it a try, I have seen its extensive use in ICU/CCU. It's like when pulse oximetry first came on to the general market [handheld ect.] many people thought of it as a robotic doctor,and yes we are very fortunate for these instruments, they play a vital role in emergency care/surgical care, but I doubt [in our lifetime] we will see a portable AI doctor :-).

My opinion if it helps the patient, then why of course, use it, or use both until you feel comfortable!

BUT professional training must be a necessity [unless you understands those manuals lol joking]

Stay safe and regards

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What an awesome tool! Our agency just switched from LifePak10's to the Philips MRX monitor w/12 lead & capnography (which rocks!). I monitor almost any patient with SOB or decreased LOC with the non-intubated oral/nasal canula. It's great to see any patient that are broncho-constricted and watch an obstructive waveform change to a normal waveform with treatments. It's the gold standard for intubated patients. It's funny to bring the patient into the ER, the nurses have NO clue what it is...they think your crazy or something.

Also, I think some states in the mid-west are measuring EtCO2 for cardiac arrest patients and anything less than 8mmHg they're ending the code.

I highly suggest getting to any Bob Page lecture, well worth any money being charged. He does "Capnography: Riding the waves" and his 12-Lead course is phenomenal!![/font:4c4fd3ea80]

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Capnography has its advantages, when relating to correct endotracheal tube placement and the obvious monitoring of the lungs [condition and efficiency], and yes rather simple to use, however this analytical instrument is not a robotic doctor, it will not tell you how to treat patients. Moreover, it may provide the medical team with more sustainable respiratory indictors, to help maintain successful respirations, I am sure my Philips MRX has this capability, although I have never used it, but may give it a try, I have seen its extensive use in ICU/CCU. It's like when pulse oximetry first came on to the general market [handheld ect.] many people thought of it as a robotic doctor,and yes we are very fortunate for these instruments, they play a vital role in emergency care/surgical care, but I doubt [in our lifetime] we will see a portable AI doctor :-).

My opinion if it helps the patient, then why of course, use it, or use both until you feel comfortable!

BUT professional training must be a necessity [unless you understands those manuals lol joking]

Stay safe and regards

Agreed Mate;

Thank you, perhaps we are getting lead down the garden path just a touch, the pulse oximeter is a tool to assist in diagnosis of OXYGENATION. The ETCO2 is used to evaluate VENTILATION.

To evaluate changes in EtCO2 wave forms due to bronchodilator therapy is really stretching "the plastic brain" capabilities at this point in time; did I mention the truth as well?

ps Hypoxia kills far more quickly than Acid Blood Base imbalances, don’t throw the Pulse Oximeter out with the bath water, I know that Rid is not suggesting this.

Granted this device has been used very effectively in the OR and ICUs for years alerting ICU Staff and Anesthetists to very serious situations, misplacement or the tube, recovery from paralytic drugs, ventilator failure, loss of volume, and a new trend for use in Dental offices to assess ventilation in the sedated patient in fact Volumes of literature exist concerning these and many other situations.

The efficacy of the ETCO2 in bronchodilator therapy, in a Field setting is not the panacea proposed by some.

I would hope that these newfound tools would be positively used to educate all staff in the Emergency setting, and not used to be brash especially when one does not have the in depth background needed to teach a very complex subject.

Beware as you may look like you have no CLUE! and DHYHOI….don’t hang your hat on it!

In a perfect world:

What is really needed to assess efficacy pre and post bronchodilator therapy is flow volume waveform loop studies (this is a closed system) thus a definitive diagnosis in improvement of ventilation status, some state of the art ICU Vents are capable, and sometimes I believe that they could was laundry too.

I remain very skeptical of the quoted study, unfortunately some believe anything that Bledsoe puts into print is indisputable as his status of a true demigod exists in some populations of EMS community. The quoted SUMMARY of the conclusion of a research paper with a very small demographic in the asthmatic population…. in fact only 39 entered in the study. I do not dispute in the slightest that correlation of PaCO2 and EtCO2 is not valid, the variation could be somewhat misleading as many many variable factors as V/Q mismatch, and underling pathologies may complicate this for example an exacerbation of Asthma preceded by a lobar pneumonia. (All that wheezes is not always Asthma!)

A great in the field tool is serial assessment with the Peak Flow Meter, in the non-intubated patient, asthmatic. In saying so this “nasal cannula application” is frankly a good step forward for paramedics and improvement in understanding the pathophysiology, but it should only be used in my humble estimation be used a effective means for “trending” ventilation and may indicate impending ventilatory failure ie a Rapid Rise in readings.

One point I would like to make for the newer readers and users is that during an Intubation Attempt. Do not rely on the capnography wave form until at least 5 breaths return and are similar morphology, the rational being that during manual (BVM) rebreathed air/CO2 may enter the stomach and artificially produce a positive reading.

squint

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Actually, if you read any literature you will find the standard protocol or operation is to give the patient 7 breaths to perform "a wash-out", before evaluating the wave form. The same is true to allow pre-oxygenation (3 minutes) or 7 breaths.

I totally disagree with you on "peak- Flow " meter. In my opinion it is a WORTHLESS tool and SHOULD NOT be used in the Emergency or pre-hospital setting. First, the patient has to perform deep inspiratory breathing and exhale fully...hence Peak Flow. Then this should be performed at least 3 times over a period of 5 minutes to get an accurate record. Is your patient that stable to perform that tasks ? That is why most ER's have totally abandoned the use of the device. With EtC02 you get an immediate reading without stress to the patient.

There are MANY literature out there in praises of the EtC02, capnography with wave form. Dr. Krauss, describes this tool as important or equal to ECG monitoring. Although Sp02 is essential to monitor the saturation, EtC02 which monitors the ventilation, in which we deal with continuous.

This tool has more applications than just to verify tube placement, monitoring perfusion level in capture of pacing, return of spontaneous pulse (in which Co2 level will improve before perfusion of pulse is felt) as well as effective CPR and PEA syndromes. Many are not aware of ability to use for aid in diagnosing questionable DKA. No it is not a cure all or should not be thought as nothing more than another tool to aid in our diagnostic skills. The same as ECG, etc..

Again, PROPER education, and applying to clinical skills enhances the uses. Yes, it does have its limitation , like other medical equipment, most with improper use or poor maintenance.

If one does a web search you will find MANY research articles out there other than Bledsoe opinion. It is a shame most EMS is not utilizing this device, rather placing money into other equipment which will not be used or provide information.

Good luck,

R/R 911

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Ridryder 911 Actually, if you read any literature you will find the standard protocol or operation is to give the patient 7 breaths to perform "a wash-out", before evaluating the wave form. The same is true to allow pre-oxygenation (3 minutes) or 7 breaths

Hmmm 5 or 7? Sounds just a bit snotty Rid, whatever, the information point here would be that some folks are maybe new to these devices and could benefit from professionals that use this equipment routinely. The recent improvement of this technology and the advantages of qualitative vs the old disposable (quantitative, colored paper) in my personal opinion whatever its worth very dated and not cost effective technology.

I totally disagree with you on "peak- Flow " meter. In my opinion it is a WORTHLESS tool and SHOULD NOT be used in the Emergency or pre-hospital setting. First, the patient has to perform deep inspiratory breathing and exhale fully...hence Peak Flow. Then this should be performed at least 3 times over a period of 5 minutes to get an accurate record. Is your patient that stable to perform that tasks ? That is why most ER's have totally abandoned the use of the device. With EtC02 you get an immediate reading without stress to the patient.

I hear what you are saying, on this point perhaps a Qualifier may the ACUITY of the Patient obviously attempting to do serial Peak flows would be counter productive in the "one word sentence club" it is a matter of the right tool for the right job in clinical application. A single reading is not diagnostic, the whole point of the quoted study was undertaken to establish a correlation between ETCO2 vs PaCO2 my criticism of this study was the very narrow snap shot in clear reference to the very small population base.

A blanket statement "chuck that out Peak Flow Meter down the crapper" is foolish and would infuriate the Pulmonary Specialists that I have had the pleasure to mentored, an inexpensive device to educate the Patient to evaluate there personal values (This in itself could decrease admissions to ERs, morbidity, mortality, and the acuity may decrease the rational being EDUCATION the patient has a tool to indicate when they are getting into trouble and seek help, not when they are in trouble!) Statistics are clear 1 out of 4 asthmatics are not being effectively controlled, some studies are suggestive very much higher.

I think my point may have been understood here, to reiterate: To evaluate changes in EtCO2 wave forms due to bronchodilator therapy is really stretching "the plastic brain" capabilities at this point in time (also) The efficacy of the ETCO2 in bronchodilator therapy, in a Field setting is not the panacea proposed by some.

There are MANY literature out there in praises of the EtC02, capnography with wave form. Dr. Krauss, describes this tool as important or equal to ECG monitoring. Although Sp02 is essential to monitor the saturation, EtC02 which monitors the ventilation, in which we deal with continuous.

A google search on "pros and cons' of capnography may reveal a surprising amount of literature.

This tool has more applications than just to verify tube placement, monitoring perfusion level in capture of pacing, return of spontaneous pulse (in which Co2 level will improve before perfusion of pulse is felt) as well as effective CPR and PEA syndromes. Many are not aware of ability to use for aid in diagnosing questionable DKA. No it is not a cure all or should not be thought as nothing more than another tool to aid in our diagnostic skills. The same as ECG, etc..

I do not dispute most of the applications you state above, if one is producing CO2 in CPR my hat comes off to them but a simple low ETCO2 reading should not be definitive in Dx of DKA I was taught that PmHx, Med Hx, and observation of breathing patterns ie Kusmal and odor may be important factors, do you not use BGL ?

My question is are you treating DKA in the field down south, perhaps I am missing something here, if you could give me a foot up in this area I would be appreciative. Thanks in advance.

Again, PROPER education, and applying to clinical skills enhances the uses. Yes, it does have its limitation , like other medical equipment, most with improper use or poor maintenance.

If one does a web search you will find MANY research articles out there other than Bledsoe opinion. It is a shame most EMS is not utilizing this device, rather placing money into other equipment which will not be used or provide information.

Agreed, just my personal preference when researching I try to be tempered and look at the research done buy the true experts in that particular field of expertise, defiantly EMS does need this device to improve delivery of care, no controversy there.

squint

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I agree with you Squint. The point I am trying to make is that Peak Flow (which many ER and EMS still attempts to get ) is really foolish to try to get in a asthmatic crisis. Sorry about the # of ventilation's, the reason is Medtronics has had so many reports of false reading or no readings only later to find out that a "wash out" was never performed. So a standard of at least 6 breaths is being attempted to be made. The same as research is showing a very low to no Co2 level that no rescitation measures should be made ( M & M has never shown any success)

The uniqueness in this tool, is we are actually bringing into the ER setting more than the opposite. It went from O.R. to ICU to field. Yes, it definitely has it's limitations.

Far as DKA, sure hx. and assessment, but those difficult cases with a glucose of 350mg/dl and they are just starting a Kussmaul respiratory drive, you can assess the Co2 level which will become significant less in time. The same is true when using Beta [sub:521ff2d6ce]1[/sub:521ff2d6ce] respiratory medications, to assess effectiveness or should combination neb.'s be administered.

Respectfully,

R/R 911

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I agree with you Squint. The uniqueness in this tool, is we are actually bringing into the ER setting more than the opposite. It went from O.R. to ICU to field. Yes, it definitely has it's limitations.

Far as DKA, sure hx. and assessment, but those difficult cases with a glucose of 350mg/dl and they are just starting a Kussmaul respiratory drive, you can assess the Co2 level which will become significant less in time. The same is true when using Beta [sub:da3750ee2d]2[/sub:da3750ee2d] respiratory medications, to assess effectiveness or should combination neb.'s be administered.

Respectfully,

R/R 911

RID...PLEASE STOP AGREEING ITS NO FUN AT ALL!! :twisted:

So thats how you spell Kussmaul, damn it! can I say that here? :dontknow:

It has been noted that when trending, in the Acute Asthmatic Patient when (CO2)/ETCO2 start's to Rise, that this can be an ominous sign, as this may be an indication that the Respiratory Pump is crapping out, and time to Chew on Plastic. Most Asthmatics can compensate for the Lactic Acidosis for SOME time, but dependent on reserve, thought I would slip that in there while I was on a roll.

Back at you respectfully: :salute:

squint

Has anyone out there, ever used Ventolin, (sorry I will talk in yall "Albuterol") for very high serum Potassium?

We have had some success in this anecdotal [sp]) but I can not find anything in the lit studies, up to one full point in (mEq/L.)

I read somewhere that it may be a cellular shift, perhaps useful in DKA, I better had qualify that in DKA initially high serum but ( total body potassium decrease.)

???

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We have used in ER for initially tx but, I only it seen it drop the K+ a very points.

The usual tx. of curse is Kayexalate, or (Sodium polystyrene sulfonate ) per mouth if possible (NG tube or per rectal per enema (which I hate administering this way it is very thick and actually has consistency of syrup) . and the usual D50W with Insulin (usual dose is one unit of Insulin Regular IV per each 2 grams of Dextrose) .. some do administer Sodium Bicarbonate to reduce the pH and due to the low sodium as well.

I have read once that it the benefit that it worked fast, however not very effective. Of course just lowering a few points in hyperkalemia is beneficial. Since most of the time we do not have current labs, unless they are dialysis or hospitalized/clinic patients.

Be safe,

R/R 911

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