Which factor places a person at risk for developing hepatitis A?

Choice D rationale

A panic attack typically involves hyperventilation, where the person breathes rapidly and deeply. This causes them to blow off excessive amounts of carbon dioxide (CO2). According to the arterial blood gas values, a low PaCO2 (less than 35 mmHg) leads to an increase in pH (greater than 7.45), resulting in respiratory alkalosis. Choice D shows a pH of 7.49 and a PaCO2 of 28 mmHg, with a normal HCO3 of 24 mEq/L, which perfectly illustrates the acute respiratory alkalosis expected during hyperventilation.

Choice A rationale

Choice A represents a state of mild metabolic acidosis or a near-normal result, with a pH of 7.34 and a PaCO2 of 45 mmHg. In a panic attack, the primary change is a decrease in CO2 due to rapid breathing, not an increase or a drop in pH. This profile suggests the body is retaining too much acid or losing base, which is the physiological opposite of what happens when a person hyperventilates during an episode of intense acute anxiety or panic.

Choice B rationale

Choice B reflects respiratory acidosis, indicated by a low pH of 7.32 and an elevated PaCO2 of 49 mmHg. This occurs in conditions where ventilation is inadequate, such as chronic obstructive pulmonary disease or respiratory depression, leading to the retention of carbon dioxide. In a panic attack, the person is over-ventilating, not under-ventilating, so the PaCO2 should be low and the pH should be high, making this result incorrect for the described clinical scenario.

Choice C rationale

Choice C shows a pH of 7.46 and an HCO3 of 28 mEq/L with a normal PaCO2. This indicates metabolic alkalosis. While the pH is high, the cause is an excess of bicarbonate rather than a deficit of carbon dioxide. In a panic attack, the alkalosis is driven by the respiratory system (low PaCO2) rather than a metabolic gain of base. Therefore, this result does not align with the rapid breathing and CO2 loss characteristic of a panic-induced hyperventilation event. .

Choice A rationale

Dehydration leads to a decrease in total plasma volume, which subsequently increases the concentration of cellular components such as red blood cells and platelets. This state of hemoconcentration increases blood viscosity, which slows the flow of blood through the venous system. According to Virchow's triad, venous stasis and changes in blood constituents are major risk factors for the formation of thrombi, thereby significantly increasing the risk of developing a deep vein thrombosis.

Choice B rationale

Trauma to the venous system causes direct injury to the endothelial lining of the vessel wall. Endothelial damage exposes the subendothelial matrix and releases tissue factor, which activates the coagulation cascade and promotes platelet aggregation at the site of injury. This disruption of the normally thromboresistant vascular surface is a primary component of Virchow's triad, making venous damage from trauma a high-risk factor for the initiation and progression of a deep vein thrombosis.

Choice C rationale

Taking anticoagulants is an intervention designed to decrease the blood's ability to clot by interfering with various stages of the coagulation cascade. These medications, such as heparin or warfarin, extend the time it takes for a fibrin clot to form. Consequently, this pharmacological management significantly lowers the risk of developing a deep vein thrombosis. It is a preventative or therapeutic measure rather than a risk factor for the development of new venous clots.

Choice D rationale

Avoiding the crossing of legs is a behavioral strategy used to prevent the mechanical compression of the popliteal veins. Compression of these veins can lead to venous stasis, where blood flow is restricted and pools in the lower extremities, creating an environment conducive to clot formation. By maintaining unhindered venous return, the person reduces one of the key elements of Virchow's triad, thereby placing themselves at a lower risk for developing deep vein thrombosis.

Choice E rationale

Tobacco use introduces various toxins, including nicotine and carbon monoxide, into the bloodstream, which cause systemic inflammation and oxidative stress. These chemicals damage the vascular endothelium and increase the levels of fibrinogen and platelet reactivity, leading to a prothrombotic state. Additionally, smoking is associated with increased blood viscosity. These combined factors significantly elevate the risk of thrombus formation in the deep veins, contributing to the overall cardiovascular burden on the individual.