Waveform Capnography Application for the prehospital provider - Maika Dang, MD CMTE University of Washington EMS Fellow

Waveform Capnography
    Application for the
   prehospital provider
Maika Dang, MD CMTE
University of Washington EMS Fellow
                      Maika Dang, MD, CMTE

                University of Washington EMS Fellow

Overview
• Carbon Dioxide
• Waveform Capnography
• Physiology and Pathophysiology

“CO2 is the smoke from the
                             flames of metabolism”
                                      - Raymond Fowler, MD

“Capnos” = Greek for smoke

Carbon dioxide
 byproduct of
   cellular
 metabolism
Glucose + O2 → CO2 + H20

Carbon dioxide diffuses
      into the blood

• Bicarbonate – 70%
• Bound to hemoglobin – 20%
• Dissolved in blood – 10%

Carbon dioxide is eliminated
through the lungs

The Evolution of CO2 Detection

Colorimetric
Capnometry
Capnography

Capnography

• Continuous numerical and
  waveform measurement of
  exhaled CO2 concentration

[CO2]

Lets Get Oriented
       ECG TRACING      O2 SAT

CO2 QUANTITY                     CO2 TRACING

Capnography is not just for the ALS provider

Capnography
Most sensitive
for detecting
hypoventilation

                  Emergency Department
                        Airway Monitoring
                               AMS
                        Procedural Sedation

                                        EtCO2 >>> RR or O2 sat…

Let’s talk bagging

EtCO2

Two Hand
Technique
            Effective Bagging

Effective Bagging
        Two person bagging better than one

• Jaw Thrust
• Face into the mask
• Light downward pressure with thumbs
• Bring face into mask with upward pressure

EtCO2
• Quality of the mask seal
• Current ventilator status
• Potential EtCO2 target

22 yo male reportedly took MDMA found seizing and hyperthermic
                  Requiring airway management

           EXAMPLE USING EtCO2 with BVM

Prior to intubation

    End tidal ~ 25

Intubation

Approximately 45 seconds no ventilations during intubation

                      End tidal ~ 70

Arrival to hospital
What do you think of this patient’s metabolic state?
   How to you want to ventilate this patient?

Lets do a case…
• 34 yo male polysubstance overdose with respiratory depression.
   • RSI - ketamine & rocuronium

The Second
 Attempt

             • Second pass attempt a success!
             • What is happening here?

Cuff leak or hypopharyngeal ETT

          Waveform prior inflating balloon

Rebreathing

Return of spontaneous respirations

    Curare Cleft

The sixth
vital sign

EtCO2
25 mmHg
   DKA
  Sepsis

What is going on here?

      Case of difficulty breathing

Bronchospasm

Changes with treatment

PaCO2 – EtCO2 gadient
When the end tidal reading does not accurately reflect the arterial CO2

Normal PaCO2 – EtCO2 gradient is within 5 mmHg

EtCO2 accurately
reflects PaCO2 when

  Normal perfusion state
         (delivery)
           AND
  Normal ventilatory state
      (gas exchange)

This gradient is
  invariable
    positive

PaCO2 ≥ EtCO2

The CO2 Gradient is determined at the level of the alveoli

Atelectasis                                                         PE
Mucus plug                                                          Reduced CO
Pulmonary edema                                                     Shock
Pneumonia                                                           Cardiac arrest
Mainstem ETT                                                        ETC…
ETC…

For example…
50 yo male s/p total knee arthroplasty 1 week c/o of shortness of breath, chest and
leg pain with swelling.
    • HR 125
    • BP 110/80
    • RR 22
    • O2 88% RA
                                          And
            as your are collecting his history he arrests in front of you…

Post Intubation Initial EtCO2 10

Transported to emergency department with ongoing CPR

          After 50 minutes of resuscitation
                     EtCO2 5-10
         However, ABG pH 6.9 and PaCO2 135

✓   Verification of ETT
✓   Visualization of ventilations
✓   Quality of chest compressions
✓   ROSC
✓   Prognostication

Ventricular Fibrillation

           End tidal ~ 20-25

       What do you do with this?

Bring the lightning!

ROSC

          End tidal ~ 50 (EtCO2 25 prior to defibrillation)

EtCO2 rise > 10 mmHg specific but not sensitive for ROSC
                  LOOK FOR TRENDS

Bicarb administration
       Don’t be fooled…

EtCO2 50

EtCO2 30

EtCO2 20

           EtCO2 10
                      Another case with ROSC!

Termination of resuscitation

EtCO2 ≤ 10 mmHg after 20 mins 100% mortality

                                               ”ACLS is for dentist”

Last case: A fender bender…
         Polytrauma + TBI = bad day

22 yo male MVC. Unresponsive, initial GCS 3 sluggish pupils.
Large hematoma right temple with bruising to chest and
abdomen and a right closed femur deformity.
Intubate with ketamine and rocuronium
    • HR 125
    • BP 90/60
    • O2 95% BVM w/ RR 18 at 100 FiO2

How are you going to ventilate your patient if?
1.   EtCO2 70
2.   EtCO2 20

CO2
         &
Cerebral Blood Flow

Trauma
PaCO2-EtCO2 gradient

EtCO2 accurately
reflects PaCO2 when

  Normal perfusion state
         (delivery)
           AND
  Normal ventilatory state
      (gas exchange)

Polytrauma with TBI

How are you going to ventilate your patient if?
1.   EtCO2 70
2.   EtCO2 20

     If EtCO2 is high → target eucapnia
         If EtCO2 is low → “Let it go”

Summary
                            Ventilation
    Waveform capnography    Perfusion
    reflects                Metabolism

                            Use it to guide ventilations
    Waveform capnography    Recognize common waveforms

    is the 6th vital sign   Guide therapeutics
                            Diagnostic utility

    Understand the PaCO2-EtCO2 gradient and
    how to apply to your patient

References
•   Abramo TJ, Wiebe RA, Scott S, Goto CS, McIntire DD. Noninvasive capnometry monitoring for respiratory status during pediatric seizures. Crit Care Med 1997;25:1242–6.

•   Eberle, B., et al. “Checking the Carotid Pulse Check: Diagnostic Accuracy of First Responders in Patients with and without a Pulse.” Resuscitation, vol. 33, no. 2, 1996, pp. 107–116.,
    doi:10.1016/s0300-9572(96)01016-7.

•   Hunter CL, Silvestri S, Ralls G, et al. A prehospital screening tool utilizing end-tidal carbon dioxide predicts sepsis and severe sepsis. Am J Emerg Med 2016; 34:813.

•   Kolar, M., Krizmaric, M., Klemen, P., and Grmec, S. Partial pressure of end-tidal carbon dioxide successful predicts cardiopulmonary resuscitation in the field: a prospective observational study. Crit
    Care. 2008; 12: R115

•   Levine, R.L., Wayne, M.A., and Miller, C.C. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest. N Engl J Med. 1997; 337: 301–306

•   Lee, Sung-Woo, et al. “Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain Injury.” The Journal of Trauma: Injury, Infection, and Critical Care, vol. 67, no.
    3, 2009, pp. 526–530., doi:10.1097/ta.0b013e3181866432.

•   Mishra, Lal Dhar. “Cerebral Blood Flow and Anaesthesia : a Review.” (2005).

•   Solmeinpur H, et al. Predictive Value of Capnography for Diagnosis in Patients with Suspected Diabetic Ketoacidosis in the Emergency Department. West J Emerg Med 2013;
    (www.escholarship.org/uc/item/5qz744fv).

•   Tat LC, Ming PK, Leung TK. Abrupt rise of end tidal carbon dioxide level was a specific but non sensitive marker of return of spontaneous circulation in patient with out-of-hospital cardiac arrest.
    Resuscitation. 2016; 104:53–58.

•   Tibballs, J., and P. Russell. “Reliability of Pulse Palpation by Healthcare Personnel to Diagnose Paediatric Cardiac Arrest.” Resuscitation, vol. 77, 2008, doi:10.1016/j.resuscitation.2008.03.098.