ETCO2 AS a Predictor of Rescusitation
Utstein style analysis of out-of-hospital cardiac arrest-Bystander CPR and end expired carbon dioxide.
Grmec S, Krizmaric M, Mally S, Kozelj A, Spindler M, Lesnik B. Resuscitation. 2006 Dec 8
A new study has confirmed the prognosticative value of end-tidal carbon dioxide monitoring in cardiac arrest showing that ETCO2 values were higher at every point in time and in every analysis for patients who were resuscitated that those who weren’t. It also reported that “in 81% of patient who had ROSC a rise in ETCO2 was the first evidence of ROSC, before a palpable pulse or measurable blood pressure was established.” No one was resuscitated who had an initial ETCO2 lower than 1.33kP (9.965 mmHG).
Conducted in Slovenia from January 2001 to December 2004, the study used an Utstein style analysis to investigate the effects of various factors on survival, including end tidal carbon dioxide. An Utstien style analysis uses a recognized template for reporting data from resuscitation studies that ensures comparability. The study found that “arrival time, witnessed arrest, bystander CPR, initial ETCO2, final ETCO2 were significantly positively related with ROSC on admission and with survival. They suggest that initial ETCO2 should be included in every Utstein style analysis.
The study observed 592 out of hospital cardiac arrests. Of that group, resuscitation was attempted on 389, which formed the study enrollment. 195 (50%) had ROSC and 82 (21%) were discharged from the hospital. ETCO2 was measured every minute during the resuscitation using a Life pack 12 beginning with the first post intubation reading
The initial ETCO2 of patients with ROSC on admission to the hospital was 18mmHG versus for 6.75 for those without ROSC. The initial value was 19.5 for those who survived versus 11 for those who did not.
The final ETCO2 values of patients with ROSC on admission was 26 mm HG versus 7.5 for those without ROSC. And the final value was 29.25 in those who survived versus 14.25 for those who died.
All patients with ROSC had an initial value of at least 9.965.
When patients had a ROSC, their ETCO2 rose by an average of 13.5mmHG before a palpable pulse or BP was detected.
Here's some info on Utstein style anaylsis:
Recommended Guidelines for Uniform Reporting of Data From Out-of-Hospital Cardiac Arrest: The Utstein Style
End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest.
Levine RL, Wayne MA, Miller CC. N Engl J Med. 1997 Jul 31;337(5):301-6.
End tidal CO2 monitoring can confirm the futility of resuscitation according to this study.
The authors studied 150 prehospital cardiac arrests where the patients were in pulseless electrical activity(PEA). V-fib, v-tack and persistent asystole were excluded as well as patients with hypothermia, trauma, poisioning, hypovolemia, cardiac tamponade, and tension pnemothorax. The group did include post defib patients with electrical activity but no pulse.
There were 115 nonsurvivors and 35 survivors to hospital admission. The initial ETCO2 on intubation were: Nonsurvivors 2-50, Survivors 5-22. After 20 minutes of CPR, the ETCO2 were: Nonsurvivors 0-10, Survivors 18-58.
The authors wrote: “No patient who had an end-tidal carbon dioxide of level of less than 10 mm HG survived. Conversely, in all 35 patients in whom spontaneous circulation was restored, end-tidal carbon dioxide rose to at least 18 mm Hg before the clinically detectable return of vital signs...The difference between survivors and nonsurvivors in 20 minute end-tidal carbon dioxide levels is dramatic and obvious.”
"An end-tidal carbon dioxide level of 10 mmHg or less measured 20 minutes after the initiation of advanced cardiac life support accurately predicts death in patients with cardiac arrest associated with electrical activity but no pulse. Cardiopulmonary resuscitation may reasonably be terminated in such patients.”
Bottom line for EMS: ETCO2 levels after twenty minutes of rescusitation can be used to help make the decision to terminate the rescusitation.
Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes?
Salen P, O'Connor R, Sierzenski P, Passarello B, Pancu D, Melanson S, Arcona S, Reed J, Heller M; Acad Emerg Med. 2001 Jun;8(6):610-5
In this study to To measure the ability of cardiac sonography and capnography to predict survival of cardiac arrest patients in emergency departments, the authors, the authors enrolled one hundred and two patients in cardiac arrest. All patients had cardiac sonography. 53 also had ETCO2 monitoring. Of the two diagnostic tests, only capnography was a significant predictor of survival.
“An ETCO2 value of 16 torr or less successfully discriminated between the survivors and the nonsurvivors in our study because no patient survived with an ETCO2 less than 16 torr. Our logistic regression model further showed that for every increase of 1 torr in ETCO2, the odds of surviving increased by 16%.”
The authors concluded: “Capnography is an outstanding predictor of survival.”
Bottom line for EMS: The higher the initial ETCO2 level, the greater the likelihood of survival. No matter what the patient may look like or the history, a high ETCO2 should ensure the best efforts of EMS to try to achieve resuscitation.
Prediction of outcome of cardiopulmonary resuscitation from end-tidal carbon dioxide concentration.
Callaham M, Barton C. Crit Care Med. 1990 Apr;18(4):358-62.
In this study of 55 nontraumatic arrests, there were 14 resuscitations. The study included patients in v-fib, EMD and asystole. Patients who developed pulse had mean initial ETCO2 of 19, those who did not had mean initial ETCO2 of 5. An initial ETCO2 of 15 correctly predicted eventual ROSC with a sensitivity of 71%, and a specificity of 98%, a positive predictive value of 91%.
“The initial PETCO2, obtained as soon as intubation was accomplished, was highly predictive of whether spontaneous pulse would be restored at any time during resuscitation.”
A key finding in the study however showed that 4 patients who developed a pulse had initial ETCO2 less than 10 mm Hg.
Bottom line for EMS: Don't give up on anyone just because their initial ETCO2 is low. Still the higher the initial reading, the better the chance of successful resuscitation.