Which diagnostic test provides the most definitive information about pulmonary function and gas exchange in patients with lower respiratory tract disorders?

A. Improved kidney function:Sodium polystyrene sulfonate is a cation-exchange resin that works within the gastrointestinal tract and does not have a direct therapeutic effect on the nephrons. While lowering potassium can prevent cardiac complications of renal failure, the drug itself does not reverse underlying kidney pathology. It is a symptomatic treatment for electrolyte imbalance.

B. Decreased serum potassium levels:This medication works by exchanging sodium ions for potassium ions across the intestinal mucosa, which are then excreted in the feces. The primary therapeutic goal is the significant reduction of potentially cardiotoxic extracellular potassium levels. It is a standard intervention for managing non-emergent hyperkalemia.

C. Increased bowel motility:While the drug can sometimes be administered with a laxative to prevent impaction, its primary pharmacological mechanism is ion exchange, not peristaltic stimulation. In some cases, it can actually cause constipation if not managed correctly. Increased motility is a side effect or secondary effect rather than the primary anticipated outcome.

D. Elevated serum sodium levels:Because the resin releases sodium in exchange for potassium, a modest increase in serum sodium can occur as a side effect. However, this is a secondary consequence that the nurse monitors for safety rather than a goal they anticipate as a therapeutic success. The focus remains on the reduction of potassium.

A. Opioids can cause constipation: This is a well-documented physiological fact rather than a myth. Opioids bind to mu-receptors in the gastrointestinal tract, leading to decreased peristalsis and delayed colonic transit time. This side effect is so consistent that a prophylactic bowel regimen is often required for patients on long-term opioid therapy.

B. Opioids interfere with over-the-counter medications: This is a factual pharmacological concern regarding drug-drug interactions. For example, combining opioids with sedating antihistamines or alcohol can lead to dangerous levels of central nervous system depression. Patients must be educated on these interactions to ensure safety during pain management.

C. Opioids are the only option for severe pain: This is a misconception, as multimodal analgesia often includes ketamine, nerve blocks, or high-dose NSAIDs to manage severe pain effectively. While opioids are powerful, they are not the sole tool available in modern pain management. Combining different classes of medications can often provide superior relief.

D. Opioids always result in addiction: This is a prevalent myth that can lead to the undertreatment of legitimate pain. While opioids have a high potential for misuse, when managed correctly under medical supervision for acute pain, the risk of developing a substance use disorder is statistically low. Addiction involves complex biopsychosocial factors.