End-Tidal CO2 (EtCO2)
The Wave Of The Future
EtCO2 Basics
EtCO2 measures ventilation
SAo2 measures oxygenation
Uses infra-red light to measure exhaled air
Vacuum in LP15 draws 50mL/min
EtCO2 Basics
Tachypnea - abnormally rapid breathing
Hyperventilation - Increased minute ventilation that results in decreased EtCO2 levels (hypocapnea)
Hypoventilation - Decreased minute ventilation that results in increased EtCO2 levels (hypercapnea)
Cellular Ventilation
Alveolar Ventilation
EtCO2 BasicsEtCO2 monitoring is continuous - changes are immediately seen (CO2 diffuses across membranes < 0.5 sec)
SAo2 monitoring relies on trending
EtCO2 Basics
Normal Values 35-45mmHg <35 = hyperventilation decreased metabolic state >45 = hypoventilation increased metabolic state
EtCO2 Basics< 35mmHg (Hyperventilation) Increased CO2 clearance (tachypnea) Decreased CO2 production (hypothermia, sedation, paralysis) Decreased delivery to lungs (decreased cardiac output) V/Q mismatch (ventilating non-perfused lungs - Pulmonary embolism)
EtCO2 Basics
> 45mmHg (Hypoventilation) Decreased central drive, muscle weakness, diffusion problems Increased CO2 production (Fever, burns, Hyperthyroidism, sz, Bicarb, ROSC, reperfusion)
EtCO2 Basics
Normal Capnogram
EtCO2 Basics
Baseline - CO2-free air in dead spaces
EtCO2 Basics
Expiratory Upstroke (exhalation)
EtCO2 Basics
Expiratory plateau (exhalation of mostly alveolar gases)
EtCO2 Basics
Inspiration (inhalation of CO2-free gases)
Bronchospasm
Normal Bronchospasm(Uneven alveolar emptying)
Emphysema
Pulmonary Edema
Poor Plateau
Differential Lung Emptying
Curare Cleft
Carbonated Beverages
Esophageal Intubation
Ineffective Respirations
Pain Management/Sedation
Hypothermia/Low Metabolic Demand
Malignant Hyperthermia
Metabolic StatesDiabetes/Dehydration EtCO2 tracks serum HCO3 & degree of acidosis ↓EtCO2 = metabolic acidosis
Metabolic States
Sepsis
EtCO2 inversely related to Lactate
The lower the EtCO2, the higher the lactate levels
Lactate levels >4 = sepsis
EtCO2 levels <25 = sepsis alert
Cardiac Output
Cardiac
CHF/Heart Failure
Cardiac Arrest