What type and amount of intravenous (IV) fluid can be given to a patient with hypotension post-appendectomy who has vomited and is not tolerating oral intake?

Postoperative Hypotension Management in a 17-Year-Old Female Post-Appendectomy

Give isotonic crystalloid fluids (normal saline or balanced crystalloid solution like lactated Ringer's) at an initial bolus of 500-1000 mL over 15-30 minutes, then reassess hemodynamic status before administering additional fluid. 1

Immediate Fluid Resuscitation Strategy

For this hypotensive patient with volume depletion from vomiting:

• Administer isotonic crystalloid solution (normal saline 0.9% or balanced crystalloid like lactated Ringer's solution) as the first-line fluid 1
• Initial bolus: 500-1000 mL rapidly over 15-30 minutes for a 17-year-old (approximately 10-15 mL/kg assuming ~60-70 kg body weight) 1
• Reassess after each bolus by checking blood pressure, heart rate, capillary refill, mental status, and urine output before giving more fluid 1, 2

Clinical Assessment to Guide Fluid Administration

Before giving additional fluid, perform a focused bedside assessment:

• Check for signs of volume depletion: dry mucous membranes, dry/furrowed tongue, sunken eyes, poor skin turgor, postural pulse change >30 beats/min, or severe postural dizziness 1
• Assess fluid responsiveness: Consider a passive leg raise test - if blood pressure improves with leg elevation, additional fluid is likely beneficial 1
• Monitor for fluid overload signs: increasing respiratory distress, crackles on lung exam, or worsening oxygen saturation 1

Ongoing Fluid Management

After initial resuscitation:

• Maintenance fluids: If still unable to tolerate oral intake, provide 25-30 mL/kg/day (approximately 1500-2000 mL/day for a 60-70 kg patient) with no more than 70-100 mmol sodium/day 1
• Replace ongoing losses: Any additional vomiting should be replaced like-for-like (approximately 500 mL isotonic fluid per large volume emesis) on top of maintenance requirements 1
• Transition to oral intake: Encourage oral fluids as soon as she can tolerate them, and discontinue IV fluids once adequate oral intake is achieved 1

Type of Fluid: Balanced Crystalloid vs Normal Saline

Prefer balanced crystalloid solutions (lactated Ringer's or Plasma-Lyte) over normal saline when available, as excessive normal saline causes hyperchloremic acidosis, decreased renal blood flow, and impaired gastric motility - all particularly problematic in a patient already experiencing vomiting 1, 3

When Fluids Alone Are Insufficient

If hypotension persists despite 1-2 liters of fluid:

• This suggests the problem is NOT primarily hypovolemia - only about 50% of postoperative hypotensive patients respond to fluid boluses 1
• Consider vasopressor support (phenylephrine or norepinephrine) rather than continuing aggressive fluid administration, which risks fluid overload 1
• Transfer to higher level of care for continuous monitoring and potential vasopressor infusion 1

Critical Pitfalls to Avoid

• Do not give excessive fluid volumes - fluid overload of as little as 2.5 L causes increased complications, prolonged hospital stay, splanchnic edema, ileus, and impaired wound healing 1
• Do not use colloid solutions (albumin, hydroxyethyl starch) - there is no benefit over crystalloids in surgical patients and potential for harm 1, 3
• Do not delay assessment - persistent hypotension requires immediate evaluation for other causes beyond hypovolemia (bleeding, sepsis, cardiac issues) 1, 2
• Do not ignore antiemetic therapy - address the vomiting with ondansetron, metoclopramide, or combination therapy to prevent ongoing losses 1