11 capnography

CAPNOGRAPHY presented by: Fred Halazon , NREMT-P Mike Burke , NREMT-P Cunningham Fire

What is Capnography? Noninvasive, continuous measurement of exhaled carbon dioxide concentration over time Digital display provides EtCO 2 value Provides a distinct waveform for each respiratory cycle

Overview History Anatomy & Physiology Capnographic waveform Diagnosing different waveforms Case studies

Relevance ETT Verification Cardiac Arrest Ventilation Bronchospastic Disease Early detection of cellular hypoxia

History of capnography Used by anesthesiologists since the 1970s Standard of care in the OR since 1991

History of Capnography in EMS Colormetric- Useful device to confirm ET tube placement in patients not in cardiac arrest Tube could be in esophagus or that circulation is not bringing CO 2 to the lungs Prone to contamination, leads to false negatives

History of Capnography in EMS Pulse oximetry preceded capnography Pulse oximetry measures oxygenation Capnography measures ventilation New technologies now allow use in EMS

Capnometry Provides only a numerical measurement of carbon dioxide ( EtCO 2 )

Capnogram A waveform display of carbon dioxide over time

Definition of Capnography Numerical value of the EtCO 2 AND Waveform of the concentration present in the airway Respiratory rate detected from the actual airflow

Definitions PACO 2 —Partial pressure of CO 2 in the alveoli PaCO 2 —Partial pressure of CO 2 in arterial blood PEtCO 2 —Partial pressure at the end of expiration PvCO 2 —Partial pressure of CO 2 in mixed venous blood PCO 2 —Partial pressure of CO 2

Definitions PaO 2 —Partial pressure of O 2 in arterial blood (hypoxemia) SPO 2 —Saturation of arterial blood (POX) percent SaO 2 —Percentage of arterial hemoglobin saturated with O 2 (POX) PO 2 —Partial pressure of O 2

What is Carbon Dioxide? Capnos comes from the Greek word for “smoke” Smoke from the Fire of metabolism Natural waste product of cellular activity CO 2 is a compound molecule 2 elements of oxygen and 1 element of carbon Colorless and heavier than air

Carbon Dioxide Transport CO 2 + H 2 O H 2 CO 3 Carbonic acid dissociates: H 2 CO 3 H + + HCO 3 _

Gas Transport in Blood O 2 carried in blood Dissolved in blood plasma Bound to hemoglobin with iron CO 2 carried in blood Dissolved in plasma (5-10%) Chemically bound to hemoglobin in (RBC’s) (carbaminohemoglobin) (20-30%) Most carried as bicarbonate ions (HCO3-) (60-70%)

Physiology of CO 2 End of inspiratory cycle, airways filled with CO 2 free gas CO 2 is a product of cellular metabolism CO 2 is continuously diffused across the cell membrane into the circulating blood

Physiology of CO 2 Transported to the lungs in the blood stream Diffused across cell membrane into alveoli Eliminated during exhalation

Oxygen > lungs> alveoli> blood Muscles + organs Oxygen + Glucose O 2 CO 2 CO 2 CO 2 O 2 cells energy blood lungs breath

Physiology of CO 2 The evolution of CO 2 from the alveoli to the mouth during exhalation, and inhalation of CO 2 free gases during inspiration gives the characteristic shape to the CO 2 curve which is identical in all humans with healthy lungs

Capnographic Waveform Expiration Inspiration Inspiration

Physiology of CO 2 Alveoli in lower lung is more perfused, but less ventilated In the more proximal respiratory tract, the CO 2 falls gradually to zero at some point

Physiology of CO 2 Concentration of CO 2 in alveoli is determined by: PERFUSION (Q) VENTILATION (V)

Physiology of CO 2 Concentration of CO 2 in alveoli: Varies INDIRECTLY with ventilation Increase Ventilation: Decrease CO 2 in Alveoli Decrease Ventilation: Increase CO 2 in Alveoli Varies DIRECTLY with perfusion Decrease Perfusion: Decrease CO 2 in Alveoli Increase Perfusion: Increase CO 2 in Alveoli

Oxygenation and Ventilation What is the difference? Oxygenation : is the transport of O 2 via the bloodstream to the cells Oxygen is required for metabolism Ventilation : is the movement of air into and out of the lungs exhaling of CO 2 via the respiratory tract Carbon dioxide is a byproduct of metabolism

Oxygenation Measured by pulse oximetry (SpO 2 ) Noninvasive measurement Percentage of oxygen in red blood cells Changes in ventilation take several minutes to be detected Affected by motion artifact, poor perfusion, temperature

Ventilation Measured by the end-tidal CO 2 Partial pressure (mm Hg) or volume (%) of CO 2 in the airway at end of exhalation Breath-to-breath measurement provides information within seconds Not affected by motion artifact, distal circulation, temperature

Distinguishing between oxygenation and ventilation

Normal Ventilation/Perfusion Ratio The volume of blood returning to the lungs matches the capacity of the lungs to exchange gases Ventilation Cardiac Output

Ventilation-Perfusion (V/Q) Mismatch Phenomenon where either perfusion or ventilation to an area of lung decreases; results in diminished gas exchange, hypoxemia, and hypercapnia

If ventilation is held constant, then changes in EtCO 2 are due to changes in cardiac output

36 5 32 4 28 3 20 2 EtCO2 (mm Hg) Cardiac Output (L)

Value of the Capnographic Waveform Provides valid EtCO 2 value Visual assessment of patient airway integrity Verify proper ET tube placement (with pulmonary perfusion) Waveforms have characteristic shape like an ECG

Capnographic Waveform Height shows amount of CO 2 Length depicts time

Phases of Capnogram Expiratory segment Consists of the following three phases

Phase I Phase I - Represents CO 2 free gas from airways (Dead Space)

Phase I Beginning of exhalation A B I

Phase II Phase II - Consists of rapid upswing (due to mixing of dead space gas with alveolar gas (Ascending Phase)

Phase II II A B C Ascending Phase

Phase III Phase III - Consists of an alveolar plateau, CO 2 rich gas, positive slope, rise in PCO 2 (Alveolar Plateau)

Phase III A B C D I I I Alveolar Plateau

Slope of Phase III CO 2 is being continuously excreted into the alveoli Late emptying of alveoli with lower (V/Q) ratios, produces higher PCO 2 End-tidal End of the wave of exhalation

Expiratory segment cont… Alpha angle - Angle between phase II and phase III (V/Q status of lung)

Phases of Capnogram Inspiratory segment Beta Angle - Angle between phase III and descending limb of inspiratory segment

Inspiratory segment Phase 0 - Inspiration, fresh gases inhaled and CO 2 falls rapidly to zero (Descending Phase)

Phase 0 A B C D E 0 Descending Phase Inhalation

End-tidal CO 2 (EtCO 2 ) Allows monitoring for changes in Ventilation —Asthma, COPD, airway edema, FBAO, stroke Diffusion —Pulmonary edema, alveolar damage, CO poisoning (COHb), smoke inhalation, hydrogen cyanide Perfusion —shock, pulmonary embolus, cardiac arrest, severe dysrhythmias

Decreased EtCO 2 Decreased Metabolism Analgesia/ sedation Hypothermia Circulatory System Cardiac arrest Embolism Sudden hypovolemia or hypotension Respiratory System Alveolar hyperventilation Bronchospasm Mucus plugging Equipment Leak in system Partial obstruction ETT in hypopharynx

Increased EtCO 2 Increased Metabolism Pain Hyperthermia Malignant hyperthermia Shivering Circulatory System Increased cardiac output with constant ventilation Respiratory System Respiratory insufficiency Respiratory depression Obstructive lung disease Equipment Defective exhalation valve Exhausted CO 2 absorber

Major Benefits in Pre-Hospital Verifying ETT placement and continuous monitoring of position during transport Cardiac Arrest Effectiveness of cardiac compression Predictor of survival Ventilation Bronchospastic Disease

Benefits in Hospital Verification of ETT placement and continuous monitoring Cardiac Arrest Ventilation Procedural sedation

ETT Displacement Most likely occurs when patient is moved

CPR Force, depth, and rate of chest compressions 100% mortality if unable to achieve an EtCO2 of 10 mm Hg after 20 minutes 4 5 0

CPR Positive pressure ventilation Increased intrathoracic pressure Pressure on Vena Cava, decreased preload Increased RR does not allow for exhalation

CPR Increased intrathoracic pressure leads to Decrease in cardiac output, coronary artery perfusion, and CPP

Optimize Ventilation Titrate carbon dioxide levels in patients sensitive to fluctuations Head Injuries Stroke Brain tumors Brain infections

Optimize Ventilation Carbon dioxide affects cerebral blood flow (CBF) Influencing intracranial pressure Hypercapnia causes vasodilation Hyperoxygenate, NOT hyperventilate Hyperventilation does not improve oxygenation Maintain CO 2 of 35-40 mm Hg

Hyperventilation Hypocapnia < 35 mmHg Normal range is 35-45 mm Hg (5% vol) How would hyperventilation change the waveform? (26-30) Frequency Duration Height Shape

Hypoventilation Hypercapnia > 45 mmHg How would hypoventilation change the waveform? (4-12) Frequency Duration Height Shape

Bronchospasm Alveoli unevenly ventilated on inspiration Asynchronous emptying during expiration Alters Phase II— “Shark Fin” shaped waveform

Bronchospasm 4 5 0 Bronchospasm

15 Sec Triage Tool Rapidly assess pt Toxins, chemical agents Spontaneous respirations Patent airway with adequate ventilation and perfusion Most acute pts Seizures

15 Sec Triage Tool Terrorism (BNICE) Absorption skin and respiratory tract Respiratory depression Trends

6 year old female Status seizure Found supine in bed with L disconjugate gaze Unresponsive to stimuli Vomiting B/P- 136/66 HR- 136 RR- 40 Skin- warm, dry, acyanotic

6 year old Tx pt to pram controlling airway Supplemental O2 Unable to establish IV Administer 5mg Valium PR B/P- 108/70 HR- 116 RR- 36

6 year old Heent- Clr Perrla Chest = rise/fall w/clr BS B/L ABD= snt Pelvis= stable SmoeX4 w/o angulation Back Clr No visual signs of Trauma

6 year old No recent medical hx or illnesses NKDA Clonidine for sleep aid at night Capnographic waveform

Decreased Cardiac Output 94 y.o. Female DNR Respiratory distress Skin- ashen, cool, dry

Case 35 y.o. male DK, combative Possible OD

Documentation Continuous waveform allows for legal documentation Proof of correct tube placement, RR, EtCO 2 Effectiveness of treatment in patient care, early detection of deterioration

The era is over when we can justify not knowing whether an ETT is in place or not. We may not be able to intubate everybody, but we must always know when the tube is in place or not.

What is up coming and how Capnography will assist The newest phase in CPR Protocols. How it will effect our decisions to work a patient or not. The CPR first protocols. Therapeutic Hypothermia.

What is Therapeutic Hypothermia Is an evidence based change in Cardiac Arrest patients This change effects treatment of the patient with a return to spontaneous pulses. The studies show good stats that back up this method of treating patients

The European Study This study was conducted in Nine hospitals and 5 countries. The Study was performed completely random. The patients were accepted into the study based on speed of response to V-fib arrest.

The Australian study Less involved study. This study took place in Melbourne and involved four hospitals This study was done Pseudo random format with patients selected based on an odd or even day.

Criteria The patient to be accepted into the study had to be a persistent V-fib arrest and still in coma state u/a to hospital. The patient must have Resuscitation efforts performed by trained personnel within 5-15 minutes of collapse. The patient must also have ROSC in under sixty minutes. The patient must also be intubated and ventilated.

European Study Procedures The patient was cooled to 32 to 34 degrees Celsius. This temp was reached in the first four hours of the resuscitation. Pt was held at this temp for twenty four hours and then passively re-warmed.

Australian Study Pt. Accepted on the same criteria however it was based on if it was an odd or even day. The pt were cooled to 33 degrees Celsius and kept there for 12 hours and the actively re-warmed after 18 hours.

The Results and they were impressive! In the European Study 75 of 136 patients(55%) had a favorable neurological outcome. In the normothermic patients the results were still good but not great at 39% The Australian Study showed a 49% save rate in the hypothermic pt and a 26% in the normothermic pt.

Why do this work? The proof is in the pudding for its benefits. However the actions is slightly more theoretical. Fist is hypothermia lowers the cerebral metabolic rate for oxygen by 6% for every 1 degree C Second hypothermia suppresses chemical reactions.

If this so great why don’t we use it! Simple Logistics The patient once taken to the hypothermic state must remain there to have benefit. A Rolla coaster approach is not going to work. The equipment to do this efficiently and controlled is expensive but is expected to fall in price as it becomes more widely spread.

Barton, C. & Wang, E. (1994). Correlation of End-Tidal CO2 Measurements to Arterial PaCO2 in Nonintubated Patients. Annals of Emergency Medicine, 23 (3): 561-562. Bergenholtz, K.F., RN, MSN, CRNP-CS. (2004). Using and understanding Capnography. Microstream capnography solutions. [email_address] Bhavani-Shankar, K., MD, Philip, JH. Defining segments and phases of a time capnogram. Anesthesiology Analg (2000). 91(4): 973-977. Bhavani-Shankar, K., MD. http://capnography.com/ Falk, J.L., Rackow, E.C., Weil, M.H. End-tidal carbon dioxide concentration during cardiopulmonary resuscitation. New England Journal of Medicine (1998) 318(10): 607-611. Fowler, Ray, MD, FACEP. www.rayfowler.com Fowler, W.S. Lung Function studies, II. The respiratory deadspace. American Journal of Physiology. (1998) 154: 405-416. Kanowitz, A., MD, FACEP, EMS Director, Arvada, CO. (2004). [Capnography in EMS]. Unpublished raw data. References

Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Annals of Emergency Medicine (2001) 37(1): 32-37. Medtronic Physio-Control Corporation (2005). http://www.healthcareeducation.org 9. Raff, Hershel, PhD, (2003). Physiology Secrets (2 nd ed.) Philadelphia, PA: Hanley & Belfus. 10.Scanlon, V.C. & Sanders, T., (1999). Essentials of Anatomy and Physiology (3 rd ed.) Philadelphia, PA: F.A. Davis Co. 11.Thompson, J.E., RRT, FAARC, Jaffe, M.B., PhD. (2005 Jan). Capnography waveforms in the mechanically ventilated patient. Respiratory Care. 50(1): 100-109. 12.Wik L, et al: “Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest.” JAMA. 293(3): 299-304, 2005. 13.Woodruff, D.W., RN, CNS, CCRN, MSN. (2006 Jan/Feb) Deciphering Diagnostics. Nursing made incredibly easy!, 4(1): 4-10.

11 capnography

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