AIPGMEE 2016 SurgeryMCQ

Postoperative fluid therapy
Q- 70 kg patient is 1 day following total hip replacement. He has not started
eating and drinking. He is being rehydrated with dextrose/saline (4% dextrose
and 0.18% saline). Which one of the following best describes this type of fluid
therapy?
A. It is an inappropriate fluid therapy for a postoperative patient
B. It contains 120 mmol of Na+ ions
C. Potassium supplementation is not required
D. Its osmolality is almost isotonic with plasma (286 mOsm/kg)
E. It has a pH of 7.35
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Answer - D Its osmolality is almost isotonic with plasma (286 mOsm/kg)
Dextrose/saline is a useful fluid therapy in the early postoperative
period because it does not cause salt and water overload and provides
some energy to the patient. Dextrose/saline solution, otherwise known
as one-fifth normal saline, has an osmolality that is nearly isotonic
with plasma because of the 4% content of dextrose. It has a slightly
alkaline pH and contains approximately 30 mmol of sodium and chloride
ions. It does not contain K+ ions and so potassium supplementation
is important if the patient is not yet established on oral intake. It
predominantly replaces pure water losses that are common following
surgery. It is less useful in hypovolaemic resuscitation as it is a less
effective plasma expander than colloid or normal saline and in patients
who are losing excess salts.