Surgical fluids & resuscitation

Q: In a lean adult, approximately what percentage of body weight is total body water, how is it divided between intracellular and extracellular compartments, and which cation predominates in each compartment?

Total body water accounts for approximately 60% of lean adult body weight, divided into two-thirds intracellular fluid and one-third extracellular fluid (interstitial fluid plus plasma). Sodium predominates in the extracellular space (so isotonic crystalloids expand extracellular fluid), whereas potassium predominates inside cells.

Q: Why is 5% dextrose (50 grams of glucose per liter of water) unsuitable for intravascular resuscitation of a patient in shock?

5% dextrose supplies 50 grams of glucose per liter and contains no electrolytes. Once the glucose is rapidly metabolized by cells, the remaining free water distributes across all total body water compartments (two-thirds intracellular, one-third extracellular), making it ineffective for shock resuscitation.

Q: What are the sodium and chloride concentrations of 0.9% normal saline, and what acid-base disorder is caused by infusing large volumes of it?

0.9% normal saline contains 154 millimoles per liter of sodium and 154 millimoles per liter of chloride. While useful for replacing chloride depletion from vomiting, infusing large volumes causes chloride excess and hyperchloremic normal-anion-gap metabolic acidosis, whereas balanced crystalloids (Hartmann's solution, Ringer's lactate, Plasma-Lyte) contain buffers and a lower chloride load.

Q: What are the standard daily maintenance water, electrolyte (sodium, potassium, chloride), and glucose requirements for a non-frail adult surgical patient?

Adult daily maintenance fluid requirements are 25 to 30 milliliters per kilogram per day of water (about 1.5 to 1.8 liters per day, or 63 to 75 milliliters per hour, for a 60-kilogram adult), approximately 1 millimole per kilogram per day each of sodium, potassium, and chloride, and 50 to 100 grams per day of glucose to limit starvation ketosis.

Q: Using the Holliday-Segar daily maintenance formula, what is the total daily maintenance fluid requirement for a 25-kilogram child?

The pediatric Holliday-Segar daily formula provides 100 milliliters per kilogram per day for the first 10 kilograms (1,000 milliliters), 50 milliliters per kilogram per day for the next 10 kilograms (500 milliliters), and 20 milliliters per kilogram per day for every kilogram above 20 kilograms (5 x 20 = 100 milliliters), totaling 1,600 milliliters per day (or approximately 65 milliliters per hour using the 4-2-1 hourly rule).

Surgical fluid therapy and resuscitation require a physiological approach to restoring tissue perfusion, meeting daily maintenance requirements, and...

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Surgical fluid therapy and resuscitation require a physiological approach to restoring tissue perfusion, meeting daily maintenance requirements, and replacing preexisting deficits and ongoing abnormal losses. Understanding body water distribution, crystalloid composition, daily electrolyte requirements, and targeted replacement of gastrointestinal losses prevents dangerous complications such as hyperchloremic metabolic acidosis, postoperative hyponatremia, and fluid overload. Mastery of adult and pediatric Holliday-Segar maintenance formulas, resuscitation bolus protocols, and safe potassium replacement is essential for surgical rotations and clinical examinations.

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1.In a lean adult, approximately what percentage of body weight is total body water, how is it divided between intracellular and extracellular compartments, and which cation predominates in each compartment?

2.Why is 5% dextrose (50 grams of glucose per liter of water) unsuitable for intravascular resuscitation of a patient in shock?

3.What are the sodium and chloride concentrations of 0.9% normal saline, and what acid-base disorder is caused by infusing large volumes of it?

4.What are the standard daily maintenance water, electrolyte (sodium, potassium, chloride), and glucose requirements for a non-frail adult surgical patient?

5.Using the Holliday-Segar daily maintenance formula, what is the total daily maintenance fluid requirement for a 25-kilogram child?

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