A nurse is caring for a patient who is postoperative and receiving fentanyl via patient-controlled analgesia. The patient has a prescription for naloxone.
What is the purpose of naloxone?

Choice A rationale:

Awaiting biopsy results can certainly cause anxiety and stress, but it doesn't directly impact the physiological mechanisms that modulate pain perception.

While a patient awaiting biopsy results may be more attentive to their bodily sensations, including pain, the anxiety itself is not the primary driver of a lowered pain threshold.

It's important to address the patient's concerns and provide emotional support, but this alone may not be sufficient to manage pain effectively if anxiety is not the primary factor.

Choice B rationale:

Anxiety activates the sympathetic nervous system, which triggers the "fight-or-flight" response. This cascade of physiological changes includes:

Increased heart rate and blood pressure Muscle tension

Dilated pupils

Heightened awareness of bodily sensations

These physiological changes can amplify pain signals and lower the pain threshold, meaning that a person who is anxious may perceive pain more intensely than someone who is calm and relaxed.

This is because anxiety can reduce the effectiveness of the body's natural pain-inhibiting mechanisms, such as the release of endorphins and serotonin.

Choice C rationale:

Difficulty sleeping can also contribute to pain, but its effect on pain threshold is less direct than that of anxiety. Sleep deprivation can lead to:

Increased irritability Decreased pain tolerance Impaired cognitive function

These factors can make it more difficult to cope with pain, but they don't directly lower the threshold at which pain signals are perceived.

Choice D rationale:

Pain threshold varies among individuals due to a variety of factors, including: Genetics

Past experiences with pain Psychological factors Cultural beliefs

Coping mechanisms

It is incorrect to assume that all patients who have had surgery will have the same pain threshold.

Choice A rationale:

Metabolic alkalosis is characterized by a high pH (above 7.45), high bicarbonate (HCO3-) levels, and normal or low PaCO2. The patient's ABGs show a low pH (7.26), low bicarbonate (14 mEq/L), and low PaCO2 (30 mm Hg), which are not consistent with metabolic alkalosis.

Choice C rationale:

Respiratory alkalosis is characterized by a high pH (above 7.45), low PaCO2, and normal or slightly elevated bicarbonate levels. The patient's ABGs do show a low PaCO2, but the pH is low (acidic) and the bicarbonate is low, which are not consistent with respiratory alkalosis.

Choice D rationale:

Respiratory acidosis is characterized by a low pH (below 7.35), high PaCO2, and normal or slightly elevated bicarbonate levels. The patient's ABGs do show a low pH, but the PaCO2 is also low, which is not consistent with respiratory acidosis.

Rationale for the correct answer, B:

Metabolic acidosis is characterized by a low pH (below 7.35), low bicarbonate levels, and normal or low PaCO2. The patient's ABGs are consistent with metabolic acidosis because they show a low pH (7.26), low bicarbonate (14 mEq/L), and low PaCO2 (30 mm Hg).

Acute kidney injury is a common cause of metabolic acidosis. The kidneys play a vital role in regulating acid-base balance by excreting acids and reabsorbing bicarbonate. When the kidneys are damaged, they are unable to excrete acids effectively, leading to an accumulation of acids in the blood and a decrease in bicarbonate levels.

Additional Information:

It's important to note that the patient's low PaCO2 is likely a compensatory mechanism for the metabolic acidosis. In response to acidosis, the respiratory system tries to increase ventilation to blow off more carbon dioxide, which helps to raise the pH. However, this compensatory mechanism is often not enough to fully correct the acidosis.