GI, GU, Nutrition, and Hydration Supportive Care

GI, GU, Nutrition, and Hydration Supportive Care

Chemotherapy-Induced Nausea and Vomiting (CINV)

GI symptoms are the most common reason oncology patients call between visits, and chemotherapy-induced nausea and vomiting (CINV) is high-yield on the OCN. Memorize the five types, because prophylaxis differs:

The principle is prophylaxis before emesis starts, matched to regimen emetogenicity. Highly emetogenic regimens (cisplatin, AC) get a 5-HT3 antagonist (ondansetron, palonosetron) + NK-1 antagonist (aprepitant/fosaprepitant) + dexamethasone, often with olanzapine. Moderate regimens use a 5-HT3 antagonist plus dexamethasone. Teach scheduled versus as-needed dosing, timing before infusion, and when to call. Escalate persistent vomiting, inability to keep fluids down for 24 hours, confusion, or dehydration signs.

Diarrhea, Constipation, and Mucositis

Know two named diarrhea patterns: irinotecan (CPT-11) causes early cholinergic diarrhea (treated with atropine) and late secretory diarrhea (high-dose loperamide); immune-checkpoint colitis can be severe and is treated with corticosteroids, not antimotility agents alone. CTCAE grades diarrhea by stools above baseline (Grade 1: <4/day; Grade 3: >=7/day or incontinence). Opioid-induced constipation is predictable and is prevented, not just treated, with a stimulant laxative plus softener.

Nutrition, Hydration, and Cachexia

Assess usual weight, recent loss, appetite, dysphagia, dentition, taste change, food access, cost, and caregiver support. Refer to a dietitian early for unintentional weight loss (a loss of >=5% in one month or >=10% in six months is a malnutrition red flag), poor intake, enteral/parenteral needs, or head-and-neck/esophageal/pancreatic/gastric disease. Practical teaching: small frequent high-protein meals, oral supplements, bland foods for nausea, and team-set hydration goals.

Critically, cancer cachexia is an inflammatory, metabolic wasting syndrome driven by cytokines, not simple starvation, so it is not fully reversed by forcing calories. Explaining this reduces caregiver blame and guilt. Do not push oral intake when obstruction, severe dysphagia, aspiration risk, or end-of-life goals call for a different plan.

GU Symptoms and Renal Safety

GU concerns include dysuria, retention, hematuria, incontinence, sexual-health changes, and renal impairment. A named emergency is hemorrhagic cystitis from cyclophosphamide and ifosfamide, prevented with aggressive hydration and mesna (which binds the toxic metabolite acrolein); teach the patient to void frequently and report pink or bloody urine. Other GU risks: obstructive tumors, immunotherapy nephritis (rising creatinine), and radiation cystitis/proctitis. Escalate inability to urinate, gross hematuria with clots, fever with urinary symptoms, flank pain, sudden creatinine rise, or confusion.

Reassess every intervention: did the antiemetic work, did stool frequency fall, is the patient urinating, is weight stabilizing, and were supplies obtained before discharge.

Mucositis and Oral Care in Depth

Oral and gastrointestinal mucositis is among the most distressing toxicities, peaking around 7-14 days after many regimens and after head-and-neck radiation. Because the mucosal barrier breaks down while counts are low, mucositis is both a comfort problem and an infection portal. The cornerstone is a structured oral-care protocol: brushing with an extra-soft brush, frequent bland rinses (normal saline or a salt-and-baking-soda solution every few hours), and removal of dentures when they irritate.

The nurse teaches patients to avoid alcohol-based mouthwash, tobacco, hot or spicy foods, and acidic juices, all of which sting and worsen breakdown. Pain control may include topical agents and systemic analgesics, and severe mucositis that prevents swallowing can require IV hydration or nutrition support. Watch for white plaques or a sudden pain change suggesting candidiasis or herpes simplex reactivation, which need antifungal or antiviral therapy, not just comfort measures.

Hydration, Electrolytes, and the High-Risk Patient

Dehydration is a final common pathway for many GI and GU problems and quietly undermines treatment. The nurse tracks intake and output, daily weights when available, mucous-membrane moisture, capillary refill, orthostatic vitals, and trends in sodium, potassium, magnesium, and creatinine. Vomiting and diarrhea deplete potassium and magnesium; obstruction and renal injury can elevate them. A patient with an ileostomy, severe mucositis, head-and-neck radiation, or repeated vomiting can decompensate within a day, so the threshold for same-day evaluation is low.

Teach realistic home goals such as sipping oral rehydration fluids steadily, using anti-emetics before meals, and calling when fluids will not stay down for more than a few hours. Effective supportive care intervenes before the patient arrives in the emergency department dehydrated, hypokalemic, and too weak to continue therapy, which is the outcome these OCN questions are designed to help nurses prevent.

A practical rule the exam rewards is to quantify rather than accept vague reports: ten watery stools with dizziness, or vomiting that has prevented any fluids for twelve hours, defines urgency far better than the word diarrhea or vomiting alone, and the documented numbers drive both the triage decision and the provider's orders.