The nurse notes that there is a difference in a patient's blood pressure (BP) and heart rate (HR) when the patient changes position from supine to standing. The differences are a decrease of 20 mm Hg in systolic BP, a decrease of 10 mm Hg in diastolic BP, and an increase in the HR of 20 beats/minute.
Which interpretation would the nurse make about the patient's condition?

The correct answer is Choice D. Then start with Choice A rationale:

Choice A is incorrect because it representsmetabolic alkalosis, not respiratory alkalosis. Metabolic alkalosis occurs when there is a primary increase in the bicarbonate (HCO3) level, which causes the pH to rise above the normal range (7.35-7.45). The PaCO2 is normal in this case, indicating that the respiratory system is not involved in the acid-base imbalance.Some causes of metabolic alkalosis include vomiting, diuretic use, excessive antacid intake, and mineralocorticoid excess1.

Choice B is incorrect because it representsrespiratory acidosis, not respiratory alkalosis. Respiratory acidosis occurs when there is a primary decrease in the PaCO2 level, which causes the pH to fall below the normal range. The HCO3 is normal in this case, indicating that the metabolic system is not involved in the acid-base imbalance.Some causes of respiratory acidosis include hypoventilation, airway obstruction, chest trauma, neuromuscular disorders, and chronic lung diseases2.

Choice C is incorrect because it representsmetabolic acidosis, not respiratory alkalosis. Metabolic acidosis occurs when there is a primary decrease in the HCO3 level, which causes the pH to fall below the normal range. The PaCO2 is normal in this case, indicating that the respiratory system is not involved in the acid-base imbalance.Some causes of metabolic acidosis include diabetic ketoacidosis, lactic acidosis, renal failure, diarrhea, and poisoning3.

Choice D is correct because it representsrespiratory alkalosis. Respiratory alkalosis occurs when there is a primary decrease in the PaCO2 level, which causes the pH to rise above the normal range. The HCO3 is normal in this case, indicating that the metabolic system is not involved in the acid-base imbalance. Some causes of respiratory alkalosis include hyperventilation, anxiety, panic, fever, pain, tumor, trauma, severe anemia, liver disease, overdose of certain medicines, pulmonary embolism, pregnancy, and any lung disease that leads to shortness of breath . Respiratory alkalosis is characterized by symptoms such as breathlessness, dizziness, numbness, tingling, muscle spasms, chest discomfort, confusion, and fainting.

Choice A rationale:

Eliminating excess H+ ions (hydrogen ions) is a primary mechanism the kidneys use to buffer acidosis. In acidosis, there is an excess of hydrogen ions in the body, leading to a decrease in pH. The kidneys help regulate the body's pH by excreting hydrogen ions to lower acidity.

Choice B rationale:

Excreting excess water is not a specific acid-base mechanism related to acidosis. While maintaining proper hydration is important for overall health, it does not directly influence the body's acid-base balance in the context of acidosis.

Choice C rationale:

Eliminating excess CO2 is primarily a respiratory mechanism, not a kidney function. CO2 elimination is more related to the lungs' ability to regulate the body's pH by adjusting respiratory rate and depth.

Choice D rationale:

Reabsorbing additional HCO3- ions (bicarbonate ions) is a renal mechanism to buffer acidosis. Bicarbonate ions act as a base and can neutralize excess hydrogen ions, raising the pH of the body fluids.

Choice E rationale:

Reabsorbing additional sodium ions is not a specific acid-base mechanism related to acidosis. While sodium ions are important for various physiological processes, they do not play a direct role in buffering acidosis.