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 is correct because a pulmonary artery catheter is a device that measures the pressures and flows in the heart and lungs, such as the pulmonary artery pressure, the pulmonary artery wedge pressure, the cardiac output, and the mixed venous oxygen saturation. These parameters reflect the hemodynamic status of the client, which is the balance between the cardiac output and the systemic vascular resistance.

Choice B Reason: This is incorrect because a pulmonary artery catheter does not measure spinal cord perfusion, which is the blood flow to the spinal cord. Spinal cord perfusion can be affected by spinal cord injury, spinal anesthesia, or spinal surgery.

Choice C Reason: This is incorrect because a pulmonary artery catheter does not measure renal function, which is the ability of the kidneys to filter waste products and maintain fluid and electrolyte balance. Renal function can be assessed by urine output, blood urea nitrogen, creatinine, and glomerular filtration rate.

Choice D Reason: This is incorrect because a pulmonary artery catheter does not measure intracranial pressure, which is the pressure inside the skull. Intracranial pressure can be increased by brain injury, stroke, tumor, infection, or hydrocephalus.

Choice A Reason: This choice is incorrect because providing a brightly lit environment may stimulate the client and increase the intracranial pressure. A brightly lit environment is an environment that has a high level of illumination or brightness. It may be used for clients who have depression, seasonal affective disorder, or insomnia, but it does not help to reduce the intracranial pressure.

Choice B Reason: This choice is incorrect because teaching controlled coughing and deep breathing may increase the intrathoracic pressure and increase the intracranial pressure. Controlled coughing and deep breathing are techniques that help to clear the airway and improve lung expansion. They may be used for clients who have respiratory infections, chronic obstructive pulmonary disease, or postoperative complications, but they do not help to reduce the intracranial pressure.

Choice C Reason: This choice is incorrect because encouraging a minimum intake of 2000 mL (67.5 oz) of clear fluids per day may cause fluid overload and increase the intracranial pressure. 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, restricting fluid intake and using diuretics may be indicated for clients who have increased intracranial pressure.

Choice D Reason: This choice is correct because elevating the head of the bed 20° may help to improve the venous drainage and decrease the intracranial pressure. As explained above, positioning the client in a semi-Fowler's or high-Fowler's position can facilitate breathing and prevent further complications. However, elevating the head of the bed more than 30° may decrease the cerebral perfusion pressure (CPP), which is the difference between the mean arterial pressure (MAP) and the intracranial pressure (ICP). A normal CPP range is 70 to 100 mm Hg, and a low CPP (<50 mm Hg) can cause cerebral ischemia, herniation, or death. Therefore, elevating the head of the bed to a moderate angle (20°) may be optimal for clients who have increased ICP.