Why does hypoxia occur when a person has pneumonia?
Hyperinflation of the alveoli reduces surface area for gas exchange.
The infection causes blood to thicken, which reduces oxygen flow.
Exudate enters the alveoli, which impairs the diffusion of oxygen.
Swelling in the trachea results in a complete airway obstruction.
The Correct Answer is C
Choice A rationale
Hyperinflation of the alveoli is a characteristic of obstructive lung diseases like emphysema, where air becomes trapped. In pneumonia, the problem is not usually air trapping but rather the filling of the air sacs with fluid. While hyperinflation does reduce surface area in chronic conditions, the acute hypoxia seen in pneumonia is driven by the presence of inflammatory materials that physically block the interface where oxygen enters the blood and carbon dioxide exits the lungs.
Choice B rationale
While systemic infection can sometimes lead to changes in blood viscosity or coagulation, pneumonia-induced hypoxia is primarily a pulmonary ventilation and perfusion issue. The blood does not typically thicken enough to reduce oxygen flow as the primary mechanism for hypoxia. Instead, the lack of oxygenation happens at the alveolar level. The problem is not the movement of the blood itself, but the fact that the blood passing through the lungs cannot pick up enough oxygen.
Choice C rationale
Pneumonia is an inflammatory process where the alveoli fill with exudate, which is a mixture of fluid, white blood cells, and cellular debris. This exudate creates a physical barrier that increases the distance oxygen must travel to reach the pulmonary capillaries. This impaired diffusion means that even if the patient is breathing, the oxygen cannot effectively cross into the bloodstream. This ventilation-perfusion mismatch is the direct cause of decreased arterial oxygen saturation and subsequent hypoxia.
Choice D rationale
While severe infections can cause airway swelling, pneumonia specifically affects the lower respiratory tract, namely the parenchyma and alveoli. A complete airway obstruction in the trachea would result in total respiratory arrest and is not the standard mechanism for hypoxia in pneumonia. Pneumonia typically causes localized or diffuse impairment of gas exchange in the lung tissue itself. Tracheal obstruction is more commonly associated with foreign body aspiration or severe anaphylaxis rather than a typical lung infection.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
Changing positions frequently and early ambulation are essential postoperative interventions to prevent venous stasis. Venous stasis is a major component of Virchow's triad, which contributes to the formation of deep vein thrombosis in the lower extremities. If a thrombus dislodges, it can travel through the venous system to the pulmonary vasculature, causing an embolism. Physical movement promotes the skeletal muscle pump, which enhances venous return and maintains healthy circulatory flow.
Choice B rationale
Oral contraceptive medications containing estrogen and progestin are known to increase the risk of thromboembolic events. Estrogen increases the plasma concentration of clotting factors and decreases the levels of natural anticoagulants like antithrombin III. Therefore, starting these medications would increase the likelihood of developing a pulmonary embolism rather than preventing it. Patients at risk for clots are typically advised to avoid hormonal contraceptives to maintain a more balanced coagulation profile.
Choice C rationale
Reducing fluid intake can lead to dehydration and increased blood viscosity, which are significant risk factors for thrombus formation. Hemoconcentration makes the blood more prone to clotting because the ratio of formed elements to plasma increases. Adequate hydration is necessary to maintain blood volume and prevent the sludging of blood in the peripheral veins. For prevention, patients are encouraged to maintain a sufficient fluid intake unless they have a contraindication like heart failure.
Choice D rationale
Applying cold packs to the legs is not a recognized method for preventing pulmonary embolism and could potentially be harmful. Cold causes peripheral vasoconstriction, which might further slow down blood flow and increase the risk of stasis. Standard preventative care involves the use of sequential compression devices, anti-embolism stockings, and pharmacological prophylaxis. Cold therapy is generally reserved for reducing localized inflammation or swelling and does not address the systemic or mechanical risks of thromboembolism.
Correct Answer is A
Explanation
Choice A rationale
Syndrome of inappropriate antidiuretic hormone involves the excessive release of ADH, leading to significant water reabsorption in the renal collecting ducts. This process results in the production of highly concentrated urine and a marked decrease in total urine volume, known as oliguria. Normal urine output is typically ≥ 0.5 mL/kg/hr. In SIADH, the kidneys continue to retain water inappropriately despite the body being in a state of fluid volume excess, leading to concentrated urine.
Choice B rationale
Patients with SIADH typically experience rapid weight gain rather than weight loss. This weight gain is the direct result of excessive free water retention caused by the high levels of circulating antidiuretic hormone. The retained water expands the extracellular and intracellular fluid compartments. Unlike heart failure or renal failure, this fluid accumulation usually does not present with visible peripheral edema because the water is distributed evenly throughout all body fluid compartments.
Choice C rationale
Increased thirst is generally suppressed in SIADH because the patient is already in a state of fluid overload and has low serum osmolality. Thirst is a physiological response usually triggered by dehydration or high serum sodium levels. In SIADH, the serum is diluted by excess water, dropping the sodium concentration often below 135 mEq/L. Consequently, the brain's thirst center is not stimulated, and patients must often be restricted to less than 800 mL of fluid daily.
Choice D rationale
SIADH is characterized by dilutional hyponatremia, not hypernatremia. The excessive retention of free water dilutes the total amount of sodium in the extracellular fluid, resulting in serum sodium levels that are lower than the normal range of 135 to 145 mEq/L. Hypernatremia would involve a sodium concentration > 145 mEq/L and is typically seen in conditions where water is lost in excess of solute, such as diabetes insipidus, which is the physiological opposite of SIADH.
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