The document provides an overview of capnography, which is the noninvasive measurement of exhaled carbon dioxide levels. It discusses the history and use of capnography, the physiology of carbon dioxide transport and the capnographic waveform. Key benefits of capnography include verifying endotracheal tube placement, assessing effectiveness of CPR and detecting changes in ventilation early. Therapeutic hypothermia for cardiac arrest patients has shown benefits in studies, improving neurological outcomes. Capnography can help monitor patients during therapeutic hypothermia protocols.
70% in patients in cardiac arrest– clogged, no CO2-O2 exchange taking place (cellular metabolism) 5%= 35-37 mmHg Yellow could by gastric acid, drugs
CO2 enters blood, most diffuses into red blood cells, which contain the enzyme CARBONIC ANHYDRASE. The enzyme catalyzes the reaction of carbon dioxide and water to form carbonic acid: Carbonic acid then dissociates. The Bicarbonate ions diffuse out of the red blood cells into the plasma, leaving HYDROGEN IONS (HEMOGLOBIN BUFFERS THE IONS, CL- (CHLORIDE IONS) enter the red blood cell When the blood reaches the lungs, an area of lower PCO2, these reactions are reversed, CO2 is re-formed and diffuses into the alveoli. Eliminated during exhalation
O2 carried by weak bond with hemoglobin (98.5%) each hemoglobin can bind FOUR molecules of O2 (HbO2) oxyhemoglobin 10%= dissolved in blood 20%= HbCO2= carbaminohemoglobin 70%= bicarbonate ions
Stroke volume- amount of blood ejected by the left ventricle with each contraction approximately 60-80ml. Varies with age, sex, health. Tidal volume- amount of air inspired and expired in a normal breath.
Low cardiac output caused by cardiogenic or hypovolemia resulting from hemorrhage wont carry as much co2 back to the lungs, resulting in lower co2. Doesn’t mean the pt is hyperventilating, or their arterial co2 level will be reduced. Reduced perfusion to the lungs alone causes this phenomenon. Lung function is perfectly normal.
Beta angle increases with rebreathing
Hydrogen cyanide byproduct of combustion, plastics in house fires. CO= Leading cause of death from fire. Hemoglobin’s affinity for CO is over 240 times greater than O2. CO forms CARBOXYHEMOGLOBIN (COHb)
Stop compressions for 20 seconds decreased survival by 50%.
A sudden rise in EtCO 2 indicates increased cardiac output. Cardiac output immediately after ROSC is often low and drugs such as epinephrine can produce peripheral vasoconstriction, so palpating a pulse may be very difficult. The presence of an organized rhythm on the monitor accompanied by a sudden increase in EtCO 2 indicates ROSC has occurred and cardiac output has improved despite questionable pulses.
Hypercapnia causes cerebral vasodilation, which causes increased CBF, and further elevates ICP. Hypocapnia causes cerebral vasoconstriction, reduce ICP. Resulting in hypoperfusion. MAP-ICP=CPP