While monitoring a patient receiving a blood transfusion, the nurse notes an abnormal drop in blood pressure to 90/50 mm Hg and an increase in heart rate to 118 beats per minute. The patient reports chills and lower back pain.
Which type of hypersensitivity reaction is the patient experiencing?

Choice A rationale

Diphenhydramine, an H1-receptor antagonist (first-generation antihistamine), possesses significant anticholinergic properties. These properties can cause urinary retention by inhibiting detrusor muscle contraction and constricting the bladder sphincter. Assessing the bladder for distension first will determine the immediate problem and guide intervention, with a normal post-void residual volume being less than 100 mL.

Choice B rationale

Encouraging increased fluid intake might worsen the patient's condition by increasing bladder volume and potentially exacerbating urinary retention due to the anticholinergic effects of the diphenhydramine. This action should be deferred until bladder emptying status has been accurately assessed, as further filling an already distended bladder is detrimental.

Choice C rationale

While urinary catheterization may be required for severe retention, it is an invasive procedure with risks like urinary tract infection (UTI). It is premature to request this before performing a non-invasive assessment like palpating or scanning the bladder for distension to confirm the need for intervention.

Choice D rationale

Requesting an intravenous (IV) fluid bolus would be contraindicated if the patient is experiencing urinary retention. Similar to encouraging oral fluids, a bolus would increase circulatory volume and urine production, placing greater strain on a distended bladder and potentially leading to bladder overstretching or rupture if not addressed.

Choice A rationale

The Food and Drug Administration (FDA) Emergency Use Authorization (EUA) for nirmatrelvir/ritonavir (Paxlovid) specifies that it is authorized for use in adults and pediatric patients who are 12 years of age and older and weigh at least 40 kg. Stating only the age is insufficient, as the weight criterion is also essential for safe and effective dosing in the pediatric population, ensuring appropriate pharmacokinetics and minimizing toxicity risks.

Choice B rationale

Nirmatrelvir/ritonavir (Paxlovid) must be initiated as soon as possible after diagnosis of COVID-19 and within 5 days of symptom onset. This timeframe is crucial because the drug works by inhibiting the SARS-CoV-2 main protease, which is most effective during the early viral replication phase before the viral load peaks and significant organ damage occurs, thus maximizing therapeutic benefit.

Choice C rationale

A rash, especially one that is severe or progresses, can be a sign of a hypersensitivity reaction to nirmatrelvir or ritonavir, such as Stevens-Johnson syndrome (SJS) or Toxic Epidermal Necrolysis (TEN). The patient must report this immediately so the medication can be discontinued and appropriate supportive care initiated to prevent life-threatening complications.

Choice D rationale

Dysgeusia (altered taste sensation), often described as a metallic taste, is a frequently reported adverse effect of nirmatrelvir/ritonavir (Paxlovid). This occurs due to the drug's excretion in saliva. Informing the patient proactively helps to manage expectations and ensure adherence to the medication regimen despite this temporary and bothersome side effect.

Choice E rationale

Significant weight gain is not a recognized common or serious adverse reaction of nirmatrelvir/ritonavir (Paxlovid). Common side effects include dysgeusia, diarrhea, hypertension, and myalgia. Weight loss might be seen in the context of severe COVID-19 infection, but not as an expected drug effect.