Correct Answer: D

Rationale: Respiratory alkalosis is caused by hyperventilation, which lowers the carbon dioxide levels in the blood and raises the pH. This is not likely to occur in a client with a nasogastric tube on low suction. Metabolic acidosis is caused by an excess of acids or a loss of bases in the body, which lowers the pH. This can occur in conditions such as diabetic ketoacidosis, renal failure, or diarrhea. This is not likely to occur in a client with a nasogastric tube on low suction. Respiratory acidosis is caused by hypoventilation, which raises the carbon dioxide levels in the blood and lowers the pH. This can occur in conditions such as chronic obstructive pulmonary disease, asthma, or sedative overdose. This is not likely to occur in a client with a nasogastric tube on low suction. Metabolic alkalosis is caused by a loss of acids or an excess of bases in the body, which raises the pH. This can occur in conditions such as vomiting, gastric suction, or diuretic use. This is the most likely acid-base disorder to occur in a client with a nasogastric tube on low suction, as the tube removes gastric acid from the stomach.

Correct Answer: A

Rationale: Narrow, peaked T waves are a sign of hyperkalemia, which is a high level of potassium in the blood. Potassium is an electrolyte that affects the electrical activity of the heart. Hyperkalemia can cause the T waves, which represent the repolarization of the ventricles, to become narrow and peaked, indicating a rapid and excessive repolarization. ST elevation is a sign of myocardial infarction, which is a heart attack. It indicates that the myocardium, or the heart muscle, is damaged and deprived of oxygen. ST elevation is not related to the potassium level, but rather to the coronary artery blood flow. Peaked P waves are a sign of atrial hypertrophy, which is an enlargement of the atria, the upper chambers of the heart. It indicates that the atria are under increased pressure or workload. Peaked P waves are not related to the potassium level, but rather to the atrial function. Prominent U waves are a sign of hypokalemia, which is a low level of potassium in the blood. Potassium is an electrolyte that affects the electrical activity of the heart. Hypokalemia can cause the U waves, which represent the repolarization of the Purkinje fibers, to become prominent and visible, indicating a delayed and prolonged repolarization.

Correct Answer: A

Rationale: Elderly patients are at a higher risk for dehydration due to physiological changes that come with aging, such as decreased kidney function and physical changes to the body's water balance systems. Additionally, fever increases metabolic rate and fluid loss, and nausea and vomiting prevent adequate fluid intake, further increasing the risk of dehydration. While intentionally limiting fluid intake can lead to dehydration, the body's thirst mechanism in a healthy teenager is typically strong enough to prevent severe dehydration. Diarrhea can certainly lead to dehydration, but a young, otherwise healthy patient typically has a stronger ability to recover from fluid loss than an elderly patient. Infants are at a higher risk for dehydration than older children and adults due to their smaller body weight and higher turnover of water and electrolytes, but in this case, the elderly patient's multiple risk factors put them at a higher risk overall.

Correct Answer: D

Rationale: Stroke is not a cause of hyponatremia, but rather a possible complication of it. Hyponatremia is a condition where the sodium level in the blood is too low, which can affect the brain function and cause symptoms such as confusion, seizures, or coma. Stroke is a condition where the blood supply to a part of the brain is interrupted, which can cause brain damage and neurological deficits. Dehydration is not a cause of hyponatremia, but rather a cause of hypernatremia. Dehydration is a condition where the body loses more fluids than it takes in, which can affect the blood volume and the electrolyte balance. Dehydration can cause hypernatremia, which is a condition where the sodium level in the blood is too high, which can also affect the brain function and cause symptoms such as thirst, dry mouth, or lethargy. Increased secretion of aldosterone is not a cause of hyponatremia, but rather a cause of hypokalemia. Aldosterone is a hormone that regulates the sodium and potassium levels in the body by increasing the reabsorption of sodium and the excretion of potassium in the kidneys. Increased secretion of aldosterone can cause hypokalemia, which is a condition where the potassium level in the blood is too low, which can affect the muscle and nerve function and cause symptoms such as weakness, cramps, or arrhythmias. Congestive heart failure (CHF) is a cause of hyponatremia, as it is a condition where the heart is unable to pump enough blood to meet the body's needs. This can lead to fluid retention and edema, which can dilute the sodium level in the blood and cause hyponatremia. CHF can also stimulate the release of antidiuretic hormone (ADH), which increases the reabsorption of water in the kidneys and further lowers the sodium level in the blood.

Correct Answer: A

Rationale: This is correct because an electrolyte is a mineral or salt that dissolves in the body fluids and dissociates into ions, which can conduct electricity and perform various physiological functions.