 “Snapshot in time”  Assists with patient assessment BUT: –Do NOT replace eyes-on/hands-on care –Are just one piece of clinical judgment –ALL have pitfalls/malfunctions/limitations –Is more complex than ever

 Non-invasive method of determining Carbon Dioxide levels in intubated and non-intubated patients  Uses infra-red technology, to monitor exhaled breath to determine CO 2 levels numerically and bywaveform (capnogram).

 EtCO 2 is directly related to the ventilation status of the patient (as opposed to SAo2, which relates oxygenation of the patient)  Capnography can be used to verify endotracheal tube/Combi-Tube & King Airway placement and monitor its position, assess ventilation and treatments, and to evaluate resuscitative efforts during CPR

 Review of Pulmonary Anatomy & Physiology  The primary function of the respiratory system is to exchange carbon dioxide for oxygen.  During inspiration, air enters theupper airway via the nosewhere it is warmed, filtered, and humidified  The inspired air flows through the trachea and bronchial treeto enter the pulmonary alveoliwhere the oxygen diffuses acrossthe alveolar capillary membrane into the blood.

Cellular Ventilation EtCO 2 Monitoring

Alveolar Ventilation

 Measurement methods  Single, one-point-in-time (Easy-Cap).  Electronic devices  Continuous information  Utilize infrared (IR) spectroscopy to measure the CO 2 molecules’ absorption of IR light as the light passes through a gas sample.

 Electronic Devices:  Mainstream  Located directly on the patient’s endotracheal tube  Sidestream  Remote from the patient.  Mainstream sampling  Occurs at the airway of an intubated patient  Was not originally intended for use on non-intubated patients.  Heavy and bulky adapter and sensor assemblies may make this method uncomfortable for non-intubated patients.

 Sidestream sampling  Exhaled CO 2 isaspirated (at 50ml/min) via ETT, cannula, or mask through a 5–10 foot long sampling tube connected to the instrument for analysis  Both mainstream and sidestream technologiescalculate the CO 2 value and waveform.

 A new technology, Microstream, utilizes a modified sidestream sampling method, and employs a microbeam IR sensor that specifically isolates the CO 2 waveform.  Microstream can be used on both intubated and non-intubated patients.

EtCO 2 Monitoring Continuous EtCO 2 monitoring = changes are immediately seen (CO 2 diffuses across the capillary-alveolar membrane <½ second) Sa02 monitoring is also continuous, but relies on trending. - and - The oxygen content in blood can maintain for several minutes after apnea (especially w/ pre-oxygenation)

 Definitions  Tachypnea  Abnormally rapid respiration  Hyperventilation  Increased minute volume that results in lowered CO 2 levels (hypocapnia)  Hypoventilation  Reduced rate & depth of breathing that causes an increase in carbon dioxide (hypercapnia)

 EtCO 2 Numerical Values (Ventilatory Assessment)  Normal = 35-45mmHg  < 35mmHg = Hyperventilation  Respiratory alkalosis  > 45mmHg = Hypoventilation  Respiratory acidosis

 EtCO 2 Numerical Values (Metabolic Assessment)  Normal = 35-45mmHg  < 35mmHg = Metabolic Acidosis  > 45mmHg = Metabolic Alkalosis  Dependant on 3 variables  CO 2 production  Delivery of blood to lungs  Alveolar ventilation

 Increased EtCO 2  Decreased CO 2 clearance  Decreased central drive  Muscle weakness  Diffusion problems  Increased CO 2 Production  Fever  Burns  Hyperthyroidism  Seizure  Bicarbonate Rx  ROSC  Release of tourniquet/Reperfusion

 Decreased EtCO 2  Increased CO 2 Clearance  Hyperventilation  Acidosis ( ↓ HCO3 levels 2° to ↑ Hydrogen)  Decreased CO 2 production  Hypothermia  Sedation  Paralysis  Decreased Delivery to Lungs  Decreased cardiac output  V/Q Mismatch  Ventilating non-perfused lungs (pulmonary edema)

Ventilation/Perfusion Ratio (V/Q) Effective pulmonary gas exchange depends on balanced V/Q ratio Alveolar Dead Space (atelectasis/pneumonia) (V > Q =  CO2 content) Shunting (blood bypasses alveoli w/o picking up o2) (V < Q =  CO2 content) 2 types of shunting: Anatomical – blood moves from right to left heart w/o passing through lungs (congenital) Physiological – blood shunts past alveoli w/o picking up o2

 Ventilation/Perfusion Ratio (V/Q)  V/Q Mismatch  Inadequate ventilation, perfusion or both  3 types  Physiological Shunt (V<Q)  Blood passes alveoli  Severe hypoxia w/ > 20% bypassed blood  Pneumonia, atalectasis, tumor, mucous plug  Alveolar Dead Space (V>Q)  Inadequate perfusion exists  Pulmonary Embolus, Cardiogenic shock, mechanical ventilation w/  tidal volumes  Silent Unit ( V &  Q)  Both ventilation & perfusion are decreased  Pneumothorax & ARDS

More Air Less Blood V > Q Equal Air and Blood V = Q More Blood Less Air V < Q

 Components of the normal capnogram

 A - B =respiratory baseline  CO 2 -free gas in the deadspace of the airways

 B-C (expiratory upstroke)  Alveolar air mixes with dead space air

 C-D (expiratory plateau)  Exhalation of mostly alveolar gas (should be straight)  Point D = measurement point (35-45mmHg)

 D-E =inspiration  Inhalation of CO2-free gas

 Changes in the capnogram or EtCO 2 levels:  Changes in ventilation  Changes in metabolism  Changes in circulation  Equipment failure

 EtCO 2 in specific settings  Non-Intubated patients  Asthma & COPD  CHF/Pulmonary Edema  Pulmonary Embolus  Head Injury  Metabolic Illnesses

 Asthma and COPD  Provides information on the ventilatory status of the patient  Combined with other assessments, can guide treatment

 Asthma and COPD (Cont’d)  Shark fin waveform

 Asthma and COPD (Cont’d)  Ventilatory assistance and/or intubation may be considered with severe dyspnea and respiratory acidosis (EtCO 2 >50mmHg)  18% of ventilated asthma patients suffer a tension pneumothorax  New ACLS standards recommend ETI for asthma patients who deteriorate despite aggressive treatment.

 Emphysema

 EtCO 2 & CHF/Pulmonary Edema  Wave forms will be normal (there is no bronchospasm)  Values may be increased (hypoventilation) or decreased (hyperventilation)

 Pulmonary Embolus  “Normal” waveform but low numerical value (why?)  Look for other signs and symptoms

 Pulmonary Embolus  Note near “normal” waveform, but angled C- Dsection (indicates alveolar dead space)

 EtC0 2 is very useful in monitoring intubated head- injured patients.  Hyperventilation = Hypocapnia =  Cerebral Ischemia  Target EtC0 2 value of mmHg Head Injury

 Hypothermia

 Hyperventilation

 Hypoventilation

 EtCO 2 in the Intubated Patient  Identifies esophageal intubations & accidental extubations (head/neck motion can cause ETT movement of 5 cm)  Waveforms/numerical values are absent or greatly diminished  Do not rely on capnography alone to assure intubation!

 Tracheal –vs- Esophageal Intubation

 Esophageal Intubation

 Esophageal Intubation w/carbonated beverages

 EtCO 2 and cardiac output  Values <20mmHg = unsuccessful resuscitation  Low (20-30mmHg) = good CPR or recovering heart

EtCO 2 and cardiac output Sudden increase in value = ROSC Cardiac arrest survivors had an average ETCO 2 of 18mmHg, 20 minutes into an arrest while non survivors averaged 6. In another study, survivors averaged 19, and non-survivors 5.

EtCO 2 and cardiac output Successful defibrillation = pulses &  EtcO 2

EtCO 2 and cardiac output Because ETCO 2 measures cardiac output, rescuer fatigue during CPR will show up as decreasing ETCO 2. Change in rescuers – Note  values w/ non-fatigued compressor

 Right Mainstem Bronchus Intubation  Numerical Values and Waveforms may/may not change, but SAo2 will drop

Kinked ET Tube No alveolar plateau – very limited gas exchange

 Spontaneous Respirations in the paralyzed patient (Curare Cleft)

 Metabolic States  Diabetes/Dehydration  EtCO 2 tracks serum HCO 3 & degree of acidosis ( EtcO 2 = metabolic acidosis)  Helps to distinguish DKA from NKHHC and dehydration

Metabolic States

Synypnea is seen across the country and is defined as when emergency department waiting room patients have the same respiratory rate.

Troubleshooting Sudden increase in EtCO 2 Malignant Hyperthermia Ventilation of previously unventilated lung Increase of blood pressure Release of tourniquet Bicarb causes a temporary <2 minute rise in ETCO 2

EtCO 2 values 0 Extubation/Movement into hypopharynx Ventilator disconnection or failure EtCO 2 defect ETT kink Troubleshooting

Sudden decrease EtCO 2 (not to 0) Leak or obstruction in system Partial disconnect Partial airway obstruction (secretions) High-dose epi can cause a decrease (unk why) Troubleshooting

Change in Baseline Calibration error Mechanical failure Water in system Troubleshooting

Continual, exponential decrease in EtCO 2 Pulmonary Embolism Cardiac Arrest Sudden hypotension/hypovolemia Severe hyperventilation Troubleshooting

Gradual increase in EtCO 2 Rising body temperature Hypoventilation Partial airway obstruction (foreign body) Reactive airway disease Troubleshooting

Many special thanks to:  JEMS Magazine (  Peter Canning, EMT-P (  Dr. Baruch Krauss  Bhavani-Shankar Kodali MD (  Bob Page, AAS, NREMT-P, CCEMT-P  Steve Berry (  Dr. Reuben Strayer  UTSW/BIOTEL EMS SYSTEM (  Oridion Medical Systems (  Blogborgymi (  University of Adelaide, South Australia (