Correct Answer: D

Rationale: Kidney function is not indicated by the PaCO2 level, but rather by the creatinine and blood urea nitrogen (BUN) levels. The kidneys are responsible for regulating the HCO3- level, which is the other component of the carbonic acid-bicarbonate buffer system. Bicarbonate buffers are not indicated by the PaCO2 level, but rather by the HCO3- level. Bicarbonate buffers are substances that can accept or donate hydrogen ions to maintain the pH of the blood. They are part of the carbonic acid-bicarbonate buffer system, which is the main buffer system in the body. Phosphate buffers are not indicated by the PaCO2 level, but rather by the PO4^3^- level. Phosphate buffers are substances that can accept or donate hydrogen ions to maintain the pH of the intracellular fluid and the urine. They are part of the phosphoric acid-phosphate buffer system, which is the second most important buffer system in the body. Lung ventilation is indicated by the PaCO2 level, which is the partial pressure of carbon dioxide in the blood. Lung ventilation is the process of moving air in and out of the lungs, which affects the amount of carbon dioxide exhaled. The lungs are responsible for regulating the PaCO2 level, which is the other component of the carbonic acid-bicarbonate buffer system.

Correct Answer: A

Rationale: This is correct because respiratory acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to impaired gas exchange or hypoventilation, which causes carbon dioxide to accumulate in the blood. COPD is a chronic lung disease that obstructs the airways and reduces the oxygen intake and carbon dioxide output. This leads to respiratory acidosis in the patient. This is incorrect because respiratory alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to hyperventilation, which lowers the carbon dioxide in the blood. COPD does not cause hyperventilation, but rather hypoventilation. This is incorrect because metabolic alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to a loss of acids or an excess of bases in the body. COPD does not affect the metabolic system directly, but rather the respiratory system. This is incorrect because metabolic acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to an excess of acids or a loss of bases in the body. COPD does not affect the metabolic system directly, but rather the respiratory system.

Correct Answer: C

Rationale: This is incorrect because low HCO3- and high PaCO2 are signs of metabolic acidosis, not alkalosis. Metabolic acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to an excess of acids or a loss of bases in the body. This is incorrect because low PaCO2 and low HCO3- are signs of respiratory acidosis, not alkalosis. Respiratory acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to impaired gas exchange or hypoventilation, which causes carbon dioxide to accumulate in the blood. This is correct because low PaCO2 and high HCO3- are signs of alkalosis. Alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to a loss of acids or an excess of bases in the body. There are two types of alkalosis: respiratory and metabolic. Respiratory alkalosis is caused by hyperventilation, which lowers the PaCO2 in the blood. Metabolic alkalosis is caused by vomiting, diuretics, or excessive intake of antacids, which raises the HCO3- in the blood. This is incorrect because high PaCO2 and high HCO3- are signs of compensation, not alkalosis. Compensation is a process where the body tries to restore the normal pH by adjusting the levels of PaCO2 and HCO3- in the opposite direction of the primary disorder.

Correct Answer: A

Rationale: This is correct because an isotonic solution has equal solute concentration on both sides of a semipermeable membrane, resulting in no net movement of water.

Correct Answer: D

Rationale: 60 mL of urine in a 2-hour period is not very concerning for a nurse, as it is within the normal range of urine output. The average urine output for an adult is about 1 to 2 L per day, or 40 to 80 mL per hour. 720 mL of urine in a 24-hour period is slightly below the normal range, but not alarming. It may indicate mild dehydration or reduced fluid intake, but it is not a sign of fluid volume excess or kidney failure. 600 mL of urine in a 10-hour period is also within the normal range of urine output, and does not indicate any problem with fluid balance or renal function. 100 mL of urine in a 5-hour period is the most concerning for a nurse, as it indicates oliguria, or abnormally low urine output. Oliguria is defined as urine output less than 400 mL per day, or less than 20 mL per hour. It may be caused by acute or chronic kidney injury, urinary obstruction, shock, dehydration, or fluid volume excess. Oliguria can lead to fluid overload, electrolyte imbalance, acidosis, and uremia, and requires immediate medical attention.