When administering a central nervous system depressant, the nurse should closely observe for drug toxicity in which patient?

Choice A reason: Opioid tolerance does not reduce constipation; it may persist or worsen. Tolerance primarily reduces pain relief, so this is incorrect for the effect.

Choice B reason: Respiratory depression risk may not increase with tolerance, as sensitivity to this effect also diminishes. Analgesia is most affected, so this is incorrect.

Choice C reason: Euphoria typically decreases with tolerance, not increases, as receptor sensitivity drops. Reduced analgesia is the primary effect, so this is incorrect.

Choice D reason: Opioid tolerance leads to decreased analgesic effect, requiring higher doses for pain relief. This is the hallmark of tolerance, making it the correct choice.

Choice A reason: Poor medication compliance may worsen heart failure but isn’t directly linked to crackles and shortness of breath. These symptoms result from fluid overload due to reduced cardiac output, not solely non-adherence. This choice is less specific to the physiological cause described.

Choice B reason: Increased ventricular contraction force, as with inotropes like digoxin, improves cardiac output, reducing fluid backup. Crackles and shortness of breath indicate fluid overload from poor heart function, not enhanced contraction, making this choice incorrect for the symptoms’ cause.

Choice C reason: Decreased ventricular contraction force in heart failure reduces cardiac output, causing blood to back up into the lungs, leading to pulmonary edema. This manifests as crackles and shortness of breath due to fluid accumulation, making this the correct physiological explanation for the symptoms.

Choice D reason: Lack of exercise may contribute to overall heart failure progression but doesn’t directly cause crackles and shortness of breath. These symptoms stem from acute fluid overload due to impaired cardiac pumping, not deconditioning, making this choice incorrect for the immediate cause.