What is the best course of action for a patient with symptoms of vomiting and anorexia, potentially leading to dehydration and electrolyte imbalances, with possible underlying conditions like diabetes or impaired renal function?

Management of Vomiting with Inability to Maintain Oral Intake

Patients presenting with vomiting and inability to maintain oral intake require immediate assessment for volume depletion and should receive isotonic intravenous fluids (0.9% normal saline) to restore intravascular volume, followed by correction of electrolyte abnormalities and treatment of the underlying cause. 1

Immediate Assessment and Triage

Signs Requiring Emergency Intervention

Contact emergency services (911) or seek urgent care immediately if the patient has: 1

• Reduced level of consciousness or new confusion 1
• Vomiting >4 times in 12 hours or complete inability to keep fluids down 1
• Low blood pressure (systolic BP <80 mmHg or drop of 20 mmHg systolic/10 mmHg diastolic) 1
• Increased heart rate (increase by 30 bpm from baseline) 1
• Difficulty or rapid breathing 1

Signs of Moderate to Severe Volume Depletion

A patient having at least four of the following seven signs indicates moderate to severe volume depletion requiring immediate fluid resuscitation: 1

• Confusion
• Non-fluent speech
• Extremity weakness
• Dry mucous membranes 1, 2
• Dry tongue
• Furrowed tongue
• Sunken eyes

Initial Fluid Resuscitation

Route Selection

Isotonic fluids should be administered via the most appropriate route based on severity: 1

• Intravenous route is preferred for moderate to severe volume depletion with inability to tolerate oral intake 1
• Oral or nasogastric routes only if mild dehydration and patient can tolerate 1
• Subcutaneous route may be considered in geriatric patients with mild-moderate depletion 1

Fluid Type and Rate

• Start with isotonic saline (0.9% NaCl) for initial resuscitation 1, 2, 3
• In adults: administer boluses as needed to restore hemodynamic stability, monitoring blood pressure, pulse, and mental status 1
• Avoid overly rapid correction - induced change in serum osmolality should not exceed 3 mOsm/kg/H2O per hour 1
• Fluid replacement should correct estimated deficits within the first 24 hours 1

Laboratory Assessment

Essential Initial Tests

Obtain immediately: 1, 4

• Serum electrolytes (sodium, potassium, chloride, bicarbonate) 1, 4
• Serum glucose 1
• Blood urea nitrogen (BUN) and creatinine 1
• Serum osmolality (directly measured preferred, >300 mOsm/kg indicates dehydration) 1
• Arterial blood gas if severe symptoms or altered mental status 1

Electrolyte Correction Priorities

Potassium replacement is critical once renal function is confirmed: 1

• Once urine output is established and serum potassium is known, add 20-30 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO4) 1
• Do not give potassium if K+ <3.3 mEq/L until corrected 1
• Hypokalemia is extremely common with vomiting and often undertreated 5

Sodium disorders require careful management: 6, 3

• Hyponatremia with severe symptoms (confusion, seizures) requires 3% hypertonic saline 6
• Correction rate must not exceed 10 mmol/L in first 24 hours to avoid osmotic demyelination syndrome 3
• Hypernatremia requires hypotonic fluid replacement when severe 6

Antiemetic Therapy

First-Line Agents

Administer antiemetics to control vomiting and allow transition to oral intake: 1, 7

• 5-HT3 antagonists (ondansetron, granisetron) are first-line for most causes 1, 7
• Consider intravenous or rectal routes if oral not tolerated 1
• Add dexamethasone for enhanced efficacy in severe cases 1

Breakthrough Management

If vomiting persists despite initial therapy: 1

• Add agents from different drug classes (metoclopramide, haloperidol, olanzapine) 1
• Consider multiple concurrent agents through alternating routes 1
• Ensure adequate hydration and correct electrolyte abnormalities before next antiemetic dose 1

Medication Management During Acute Illness

Temporarily Stop These Medications

Patients should hold the following medications until symptoms resolve or for maximum 72 hours: 1

• SGLT2 inhibitors (empagliflozin, dapagliflozin) - risk of ketoacidosis 1
• ACE inhibitors/ARBs (perindopril, candesartan) - risk of acute kidney injury 1
• Diuretics (furosemide, hydrochlorothiazide, spironolactone) - worsens volume depletion 1
• NSAIDs - risk of acute kidney injury 1
• Insulin/sulfonylureas/meglitinides if blood glucose is low 1

Monitoring and Follow-Up

When to Seek Healthcare Provider Support

Contact healthcare provider if: 1

• Patient feels unable to cope with self-management 1
• Symptoms have not resolved within 72 hours 1
• Cannot maintain adequate fluid intake 1
• Recurrent low blood glucose readings (for diabetics) 1

Success Indicators

Monitor for improvement in: 1

• Blood pressure normalization 1
• Heart rate returning to baseline 1
• Mental status clearing 1
• Urine output restoration 1
• Ability to tolerate oral fluids 1

Common Pitfalls to Avoid

• Do not rely on clinical signs alone (skin turgor, mouth dryness) to assess hydration status in older adults - these are unreliable 1
• Do not use vasopressors until adequate fluid resuscitation is achieved, as they worsen mesenteric perfusion 1
• Do not correct sodium too rapidly - risk of permanent neurological damage from osmotic demyelination 3
• Do not forget potassium replacement - solutions often contain insufficient potassium for replacement needs 5
• Do not delay treatment while pursuing diagnostic workup if patient has severe symptoms 6