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Discussion Starter #1
In the postoperative recovery unit, a 60-year-old patient has a pulse oximetry reading in the low 90s. The patient is status post bilateral carotid endarterectomy for atherosclerosis. An arterial blood gas obtained from this patient reveals a PaCO2 of 55 mmHg. Bilateral breath sounds are clear on auscultation. What is the likely reason for his hypoxia and hypercarbia?

A. Increased metabolic demand commonly seen after surgery
B. Hypoventilation due to pain
C. Asthmatic exacerbation
D. Loss of peripheral chemoreceptors
E. Low FiO2
 

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Discussion Starter #3
Peripheral chemoreceptors located in the carotid and aortic bodies measure the concentrations of various chemicals in the blood. This information is conveyed back to the brain in order to regulate acid/base imbalances. These rapid-response sensors respond to a decreased arterial partial pressure of oxygen or increased partial pressure of carbon dioxide by increasing vagus nerve-mediated minute ventilation. This regulation is often lost after bilateral CEA's which disturb or remove the carotid bodies. These patients can have difficulty maintaining homeostasis (by increasing their minute ventilation) with respect to rising PaCO2
 
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