Hemodynamics — MCQs

Q: A 31-year-old female with a history of anxiety has a panic attack marked by dizziness, weakness, and blurred vision. Which of the following most likely accounts for the patient’s symptoms?

Decreased cerebral blood flow. ***Decreased cerebral blood flow*** - During a panic attack, **hyperventilation** leads to a drop in arterial CO2, causing **cerebral vasoconstriction** and reduced blood flow to the brain. - This reduction in cerebral blood flow manifests as neurological symptoms like **dizziness, blurred vision, and weakness**. *Oxygen toxicity* - This typically occurs with exposure to **high partial pressures of oxygen**, often in diving or hyperbaric oxygen therapy. - Symptoms include **seizures, visual changes, and nausea**; it is not associated with panic attacks or their physiological responses. *Increased arterial CO2* - Panic attacks involve **hyperventilation**, which causes a decrease, not an increase, in arterial CO2 (hypocapnia). - Increased arterial CO2 (hypercapnia) usually leads to **vasodilation**, which would increase cerebral blood flow rather than decrease it. *Carotid artery obstruction* - This condition involves a physical blockage in the carotid arteries, reducing blood flow to the brain, which can cause symptoms similar to those described. - However, such an obstruction is a **structural problem** and not an acute physiological response to a panic attack in a young patient without other risk factors. *Decreased respiratory rate* - Panic attacks are characterized by **hyperventilation**, meaning an increased respiratory rate and depth, not a decreased one. - A decreased respiratory rate would lead to an **increase in arterial CO2**, which is contrary to the physiological changes seen in a panic attack.

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