Capnography: Defined and Clinical Applications Becky Logiudice, RN, MS, CCRN Mount Auburn Hospital

What is Capnograhy? Continuous graphic display and recording of carbon dioxide concentrations during the respiratory cycle Capnography provides: Numerical value for end tidal CO2 (EtCO2) CO2 waveform for each breath Respiratory rate (RR) sampled directly from the airway EtCO2 value + Waveform + RR = Ventilation/ Airway status

History Fundamentals of capnography were established in 1943 by Karl Luft, a German Bio-engineer CO2 could absorb infrared radiation 1978: Capnography first used in Holland during anesthesia In 1998 the ASA (American Society of Anesthesiologists) Committee on Standards of Care = Mandatory during general anesthesia Present: Standard of care during anesthesia and being used more during emergency care and procedural sedation

Infrared Spectography The infrared light received is compared to the infrared light transmitted. The difference is then converted by calculations into the partial pressure that you see on the monitor.

Chemical Colorimetric Analysis Uses pH to detect CO2 Good for a quick indicator

Physiology

Process of Respiration Note: Ventilation and Oxygenation are separate, but related, processes

Capnography

Question? Are oxygenation and ventilation separate? How?

Oxygenation Ventilation http://sciencemuseumofvirginia.com

Clinical uses for capnography 1. Monitoring of airway /ventilation during: Moderate sedation General anesthesia Use of a PCA 2. Endotrachial tube placement verification 3. Detect breathing/apnea 4. Ventilator malfunction 5. Estimate cardiac output 6. Monitor adequacy of CPR 7. Identify ROSC (Return of Spontaneous Circulation)

Normal Values and Waveforms ABGs Normal CO2 values: 35 – 45 mmHg Capnography Normal EtCO2 values: 30 – 40 mmHg

Procedural Sedation Depressed ventilation is common, but clinical observation of RR is inadequate Capnography acts as an early warning for a disasterous respiratory event Pulse oximetry/electrocardiography give late warnings

Why Capnography in a code? Background: The 2010 American Heart Association Guidelines for ACLS now recommends using quantitative waveform capnography with intubated patients receiving chest compressions Purpose: Waveform capnography in intubated patients monitors: CPR quality Optimizes chest compressions Can detect return of circulation during chest compressions

CO2 and Cardiac Output

Equipment Needed for Waveform Capnography Ambu Bag Capnography Unit Capnography filter tubing ET Tube

How the Pieces Connect Ambu attaches to Capnography Filter tubing The other end of filter Capnography Filter tubing connects to unit here Filter line ribbed end attaches to ET tube

The Capnography Device Screen On/Off switch PETCO2 Reading here O2 sat here PETCO2 waveform here

What the Numbers Mean? Under normal conditions: During CPR: PETCO2 = 35 to 45mmHg During CPR: PETCO2 10 -20 mmHg = High quality chest Results that require Action: 1. PETCO2: < 10mmHG: * Check endotrachial tube placement: * Check breath sounds * Evaluate quality of chest compressions * Consider switching compressor role 2. PETCO2: 35-45mmHg * Assess for return of spontaneous circulation (ROSC) * Check pulse, check rhythm

Factors affecting CO2 levels Increase in ETCO2 Increased muscular activity (shivering) Increased Metabolism: Sepsis Fever Malignant Hypothermia Increased Cardiac output (during resuscitation) Decreased minute ventilation ( total lung ventilation per minute. Tidal volume and respiratory rate) Two main causes: Increased CO2 production Decreased excretion / alveolar ventilation

Factors affecting CO2 levels Decrease in ETCO2 Decreased muscular activity Hypothermia Decreased cardiac output Pulmonary Embolism Bronchospasm Increased minute ventilation (RR and tidal volume) Two Main Causes Decreased Production Increased Excretion or alveolar ventilation

Case Studies If intubated: Kinked ET tube ET tube dislodged Airway obstruction

Rapidly decreasing waveform Sudden hypotension Early sign of cardiac arrest Pulmonary Embolism Increase in RR

Rising Waveform Rising body temp Increased metabolism Increased BP Decrease in RR

Capnography low (20 mmHg) Hypothermia Sedation / Anesthesia Chest compressions