Examkin

Question

Difficulty: Very hardPhysiological Adaptation

A client is in the intensive care unit 48 hours after sustaining a severe traumatic brain injury. The nurse assesses the following clinical data:

ParameterCurrent Value
Blood pressure78/48 mm Hg
Heart rate134 beats/min (thready)
Respiratory rate26 breaths/min
Central venous pressure1 mm Hg
Urine output (last 2 hr)1,100 mL/hr (pale)
Serum sodium158 mEq/L (158 mmol/L)
Serum osmolality328 mOsm/kg
Urine specific gravity1.002

The client is lethargic and responds only to noxious stimuli. Which of the following is the priority nursing action?

  1. Administer a rapid intravenous bolus of 0.9% sodium chloride.Answer
  2. B
    Administer the prescribed intravenous desmopressin acetate.
  3. C
    Initiate a continuous intravenous infusion of 0.45% sodium chloride.
  4. D
    Obtain a STAT arterial blood gas to assess for respiratory alkalosis.

Answer

The priority action is to administer a rapid intravenous bolus of 0.9% sodium chloride.
The client's profound polyuria, hypernatremia, elevated serum osmolality, and dilute urine indicate central diabetes insipidus, a common complication of traumatic brain injury. However, the client is currently in hypovolemic shock (blood pressure 78/48 mm Hg, heart rate 134 beats/min, CVP 1 mm Hg) due to massive fluid loss. According to the ABCs (Airway, Breathing, Circulation) of prioritization, restoring cardiovascular perfusion is the immediate life-saving priority. Isotonic crystalloids, such as 0.9% sodium chloride, remain within the intravascular space to expand circulating volume and restore blood pressure. Failing to treat the profound hypovolemia immediately will lead to cardiovascular collapse.

Step-by-Step Solution

1
Analyze the clinical data to identify the physiological problem.
The combination of severe polyuria, hypernatremia, and low urine specific gravity following a brain injury indicates central diabetes insipidus.
Traumatic brain injury can disrupt the hypothalamus or posterior pituitary, halting antidiuretic hormone (ADH) secretion.
2
Evaluate the client's hemodynamic status.
Hypotension (78/48 mm Hg), tachycardia (134 beats/min), and a critically low CVP (1 mm Hg) confirm the client has progressed to hypovolemic shock due to massive fluid loss.
Urine output exceeding 500 mL/hr rapidly depletes intravascular volume, leading to decreased venous return and cardiac output.
3
Apply principles of prioritization (ABCs).
Circulation is severely compromised. Restoring intravascular volume to maintain organ perfusion takes priority over correcting the serum sodium level or administering hormonal therapy.
Without immediate volume resuscitation, the client will suffer irreversible ischemic organ damage or cardiac arrest.
4
Determine the appropriate fluid for shock resuscitation.
Isotonic fluids (0.9% sodium chloride) are required to rapidly expand the intravascular space. Hypotonic fluids (0.45% NaCl) will leave the vascular space and fail to reverse the shock state.
Although the client is hypernatremic, 0.9% NaCl is the standard for hypovolemic shock. Interestingly, with a serum osmolality of 328 mOsm/kg, 0.9% NaCl (308 mOsm/L) is technically hypotonic to this specific client's blood.

Key Concept

In clients with diabetes insipidus who develop hypovolemic shock, immediate intravascular volume resuscitation with isotonic crystalloids takes absolute priority over correcting hypernatremia with hypotonic fluids or administering antidiuretic hormone.
Rate this question

Topics

Physiological Adaptation

More questions from this topic