NAPLEX Question of the Week: Becoming Fluent in Fluids

How well do you know your IV fluids? Find out this week!
NAPLEX Question of the Week: Becoming Fluent in Fluids
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AP is a 67-year-old male presenting with shortness of breath, tachycardia, hypotension, confusion, and a fever. After determining probable sepsis, the acute care team initiates the sepsis bundle immediately. They draw lactate levels, cultures, and are beginning the process of initiating antimicrobials and fluids. The attending physician would like your recommendation for fluid resuscitation. Can you help AP?

Past Medical History: Hypertension, Hyperlipidemia

Allergies: Penicillin

Outpatient Medications: Lisinopril 20mg once daily, Atorvastatin 40mg once daily

Vitals: 

Heart Rate: 110 bpm  Blood Pressure: 85/62 mmHg  Weight: 70kg  Height: 5’11”  Temperature: 101.4F

Labs: 

Na: 140 mEq/L  K: 6.7 mEq/L  Cl: 102 mEq/L  Lactate: 5 mmol/L  Cultures: pending

Which of the following IV fluids would be an appropriate choice for AP’s fluid resuscitation? Multiple Choice. 

A. Lactated Ringers 30mL/kg IBW

B. Plasmalyte 30mL/kg IBW 

C. Normal Saline 30mL/kg IBW

D. D5W 30mL/kg IBW

Brands/Generics:

Zestril/Lisinopril; Lipitor/Atorvastatin

Rationale: 

Sepsis is an acute inflammatory syndrome requiring immediate treatment. It is the body’s response to an inflammatory cascade due to an infection. Patients that present with sepsis syndromes present with hemodynamic instability including hypotension (low BP/MAP). In order to ensure appropriate perfusion to organs, intravenous fluid resuscitation and sometimes vasopressors are necessary to raise the blood pressure (SBP >90mmHg; MAP >65mmHg) in septic shock. The recommended amount for initial fluid resuscitation is 30mL/kg of IBW. The recommended type of fluid to use is isotonic fluids. Isotonic fluids work by keeping around 25% of the fluid inside the blood vessels to raise blood pressure and perfusion. Hypotonic fluids are not recommended, as they leak out of the vessel and do not improve perfusion. If fluid resuscitation is not enough to maintain organ perfusion, vasopressors may be required.

Choice A is not correct due to the patient’s potassium level. Lactated Ringers contains 4 mEq/L and is not recommended in hyperkalemia. Hyperkalemia can cause dangerous arrhythmias including Torsade de pointes and cardiac arrest. It is more specifically recommended to avoid Lactated Ringers in patients whose potassium is above 6.5 mEq/L. Other situations in which Lactated Ringers should be avoided is in patients with traumatic brain injury, patients with end stage liver disease, and patients that have recently received a blood transfusion.

Choice B is not correct also due to the patient’s potassium level. Plasmalyte contains even more potassium than Lactated Ringers at 5 mEq/L and should also be avoided in patients with hyperkalemia. Hyperkalemia can cause dangerous arrhythmias including Torsade de pointes and cardiac arrest. It is more specifically recommended to avoid Plasmalyte in patients whose potassium is above 6.5 mEq/L. Other situations in which Plasmalyte should be avoided is in patients with traumatic brain injury.

Choice C is correct. Normal saline is the appropriate choice for this patient as it does not contain any potassium. Normal saline (0.9% sodium chloride) is made up of 154mEq/L of both sodium and chloride. Since this is an isotonic fluid appropriate for fluid resuscitation and the patient’s sodium and chloride levels are within normal limits, this fluid would be the appropriate answer.

Choice D is incorrect. Patients with sepsis are hypotensive, meaning they should generally be fluid resuscitated with 30mL/kg of IBW of an isotonic fluid to bring their blood pressure up, restoring perfusion to vital organs. D5W is a hypotonic fluid and would not be appropriate to fluid resuscitate the patient, as the fluid would leak out of their vessels and not improve their blood pressure.

NAPLEX Competencies Covered: 

Area 1: Obtain, Interpret, or Assess Data, Medical, or Patient Information

1.1 From instruments, screening tools, laboratory, genomic or genetic information, or diagnostic findings

Area 2: Identify Drug Characteristics 

2.1 Pharmacology, mechanism of action, or therapeutic class

2.2 Commercial availability; prescription or non-prescription status; brand, generic, or biosimilar names; physical descriptions; or how supplied 

Area 3: Develop or Manage Treatment Plans 

3.3 Medication reconciliation; indication or therapeutic uses; lack of indication; inappropriate indication; duplication of therapy; omissions 

3.6 Drug contraindications, allergies, or precautions

3.11 Evidence-based practice  

Congrats on all who are graduating! Finishing up our last live review of the season at Wingate University School of Pharmacy here in North Carolina with the Class of 2023.

Keep studying hour by hour, day by day. The reward is coming!

Dr. B

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