Pulmonary physiology Flashcards
Rightward and leftward shit of the oxyhemoglobin curve? happens when?
The oxyhemoglobin dissociation curve explains one of the compensatory mechanisms of the body during a state of shock. The oxyhemoglobin dissociation curve defines the amount of oxygen delivery that occurs in the peripheral tissues. A rightward shift of the oxyhemoglobin dissociation curve indicates that the oxygen is being unloaded to the peripheral tissues and thus assists in the healing process. A leftward shift of the oxyhemoglobin dissociation curve prevents oxygen unloading to the tissues, which, in turn, leads to further problems and worsening of the shock state. Several components occur within the body during a state of shock that shifts the oxyhemoglobin dissociation curve to the right. These include hyperthermia, metabolic acidosis, increased 2,3 diphosphoglycerate, and hypercapnia.
Carbon monoxide exposure should be treated how? what happens?
Patients suffering from exposure to carbon monoxide should be treated with 100% oxygen upon initial presentation to the emergency department. Carbon monoxide poisoning can occur at any age; however, it is more common in persons over the age of 75 years. Acute poisoning presents with malaise, fatigue, lethargy, and demonstration of flu-like symptoms. Tachycardia, cherry red skin (late presentation), skin pallor (early presentation), and flame-shaped retinal hemorrhages are classic findings on physical examination. Administration of 100% oxygen is recommended until the patient is asymptomatic and HbCO levels are below 10%. Pulse oximetry measures the percent of arterial hemoglobin in the oxyhemoglobin concentration using light emitting diodes with different wavelengths in a device typically placed on the finger or forehead. The replacement of oxygen by carbon monoxide changes the hemoglobin molecule to the carboxyhemoglobin configuration, which the pulse oximeter cannot discern from oxyhemoglobin. This is quite problematic in the evaluation of patients exposed to smoke or inhalational toxic gases. The pulse oximeter result will be read as normal or even reading 100%, which is not a true evaluation of the saturation of oxygen in the oxyhemoglobin form. Physiology of carbon monoxide toxicity is based on the super affinity of the carbon monoxide molecule for hemoglobin, which is approximately 230 times greater than that of oxygen. The formed carboxyhemoglobin molecule is unavailable for oxygen transport and shifts the hemoglobin-oxygen dissociation curve to the left, so oxygen is only unloaded then at lower oxygen tension. This formation induces a greater tissue hypoxia than even that seen in simple anemia.
