The nurse is caring for a postoperative client who has a chest tube connected to suction and a water seal drainage system. Which of the following indicates to the nurse that the chest tube is functioning properly?

Choice A Reason: This choice is incorrect because slowing the rate to 50 mL/hr may not be enough to prevent cerebral edema, which is a common complication of head injury. Cerebral edema is a swelling of the brain tissue due to increased fluid accumulation. It can cause increased intracranial pressure (ICP), which can lead to brain damage or death. Therefore, the nurse should limit the fluid intake of the client with head injury to avoid worsening the condition.

Choice B Reason: This choice is incorrect because increasing the rate to 250 mL/hr may cause fluid overload, which can also increase the ICP and worsen the cerebral edema. Fluid overload is a condition in which the body has too much fluid, which can impair the function of the heart, lungs, and kidneys. Therefore, the nurse should avoid giving too much fluid to the client with head injury.

Choice C Reason: This choice is correct because slowing the rate to 20 mL/hr may help to maintain adequate hydration and electrolyte balance, while preventing fluid overload and cerebral edema. This is a conservative approach that can be used until the client's neurological status and ICP are assessed and monitored.

Choice D Reason: This choice is incorrect because continuing the rate at 125 mL/hr may not be appropriate for the client with head injury, depending on their individual needs and condition. The nurse should adjust the fluid rate according to the client's vital signs, urine output, serum osmolality, and ICP. Therefore, the nurse should not assume that this rate is optimal for the client without further evaluation.

Choice A Reason: This choice is correct because respiratory acidosis is a condition in which the lungs cannot eliminate enough carbon dioxide (CO2) from the blood, resulting in a high level of CO2 (PaCO2) and a low level of pH. A normal PaCO2 range is 35 to 45 mm Hg, so a value of 50 mm Hg indicates respiratory acidosis.

Choice B Reason: This choice is incorrect because HCO3 (bicarbonate) is a base that helps to buffer the excess acid in the blood. In respiratory acidosis, the kidneys try to compensate by retaining more HCO3 and excreting more hydrogen ions. Therefore, a high level of HCO3 (above 26 mEq/L) would indicate a chronic or compensated respiratory acidosis, not an acute or uncompensated one.

Choice C Reason: This choice is incorrect because pH is a measure of the acidity or alkalinity of the blood. A normal pH range is 7.35 to 7.45, so a value of 7.45 indicates a neutral or slightly alkaline blood, not an acidic one. A low pH (below 7.35) would indicate respiratory acidosis.

Choice D Reason: This choice is incorrect because potassium is an electrolyte that helps to regulate the nerve and muscle function, as well as the fluid balance in the body. In respiratory acidosis, the increased hydrogen ions in the blood may shift into the cells in exchange for potassium, resulting in a high level of potassium (hyperkalemia).

Therefore, a low level of potassium (below 3.5 mEq/L) would indicate hypokalemia, not respiratory acidosis.