19. Methemoglobinemia What happens in metHb? The iron within hemoglobin is oxidized from the ferrous (Fe 2+ ) state to the ferric (Fe 3+ ) state, resulting in the inability to transport oxygen and carbon dioxide.
20. *Most common*, enzyme deficiency in RBC ’s… Widespread deficiency of enzyme in multiple tissues, erythrocytes, liver, fibroblasts, and brain. Associated with severe CNS symptoms, MR, cyanosis and premature death… Hemopoietic system involved; platelets, RBC ’s, white cells only main consequence is cyanosis… Similar to type I, isolated erythrocyte involvement resulting in chronic cyanosis…
26. Met-Hgb how do you make the diagnosis? -Diagnosis confirmed by direct measurement of methemoglobin by a multiple wavelength co-oximeter ABG- Normal PaO 2 Concentrations are usually found on analysis ** Clinical cyanosis is the presence of normal arterial oxygen tensions is highly suggestive of methemoglobinemia** The arterial oxygen tension is related to the amount of oxygen dissolved in blood plasma, not the much larger pool that is bound to hemoglobin…
27.
28. Pulse oximeter Pulse oximetry is a simple non-invasive method of monitoring the percentage of hemoglobin (Hb) which is saturated with oxygen. An oximeter detects hypoxia before the patient becomes clinically cyanosed. How does an oximeter work? A source of light originates from the probe at two wavelengths (660nm and 940nm). The light is partly absorbed by hemoglobin, by amounts which differ depending on whether it is saturated or desaturated with oxygen. By calculating the absorption at the two wavelengths the processor can compute the proportion of hemoglobin which is oxygenated . Pulse oximetry cannot distinguish between different forms of hemoglobin. Carboxy-hemoglobin (hemoglobin combined with carbon monoxide) is registered as 90% oxygenated hemoglobin and 10% desaturated hemoglobin - therefore the oximeter will overestimate the saturation. The presence of methemoglobin will prevent the oximeter working accurately and the readings will tend towards 85%, regardless of the true saturation. A CO-oximeter measures absorption at additional wavelengths to distinguish CO from O 2 and determines the blood oxygen saturation more reliably.
29. Pulse oximeter Methemoglobin increases absorbtion of light at both wavelengths (more at 940nm) Met-Hb offers optical interference to the pulse oximetery by falsely absorbing light This leads to the plateau in the oxygen saturation at 85%. Co-oximetry is KEY
30.
31.
32. metHb-Blood Looks Like Chocolate metHb oxygentated blood………….. blood
49. Clinical Characteristics of Angina Characteristic More likely to be angina Less likely to be angina Type of pain Dull, pressure Sharp, stabbing Duration 2 to 5 min, always <15–20 min Seconds or hours Onset Gradual Rapid Location Substernal Lateral chest wall, back Reproducible With exertion With inspiration Associated symptoms Present Absent Palpation of chest wall Not painful Painful, exactly reproduces pain complaint
![History ,[object Object],[object Object],[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)