Select the Manifestations of increased intracranial pressure

Choice A rationale

When dehydration occurs, the total blood volume decreases, leading to a drop in blood pressure. The body compensates through the baroreceptor reflex, which detects the decrease in stretch within the carotid sinuses and aortic arch. This triggers the sympathetic nervous system to increase the heart rate, known as tachycardia. By increasing the heart rate, the body attempts to maintain adequate cardiac output and ensure that vital organs continue to receive sufficient oxygenated blood despite the lower circulating volume.

Choice B rationale

Dehydration leads to a decrease in skin elasticity, often referred to as poor skin turgor. When the body is dehydrated, fluid is pulled from the interstitial spaces and intracellular compartments to maintain vascular volume. This loss of fluid from the dermal layers causes the skin to lose its resiliency. Scientifically, skin that stays "tented" when pinched is a classic sign of dehydration, representing a failure of the compensation mechanism to keep peripheral tissues hydrated during a fluid deficit.

Choice C rationale

In response to dehydration and increased serum osmolality, the posterior pituitary gland actually increases the secretion of antidiuretic hormone, also known as vasopressin. This hormone acts on the collecting ducts of the kidneys to increase water reabsorption, thereby concentrating the urine and conserving as much fluid as possible. A decrease in antidiuretic hormone secretion would lead to more fluid loss through urine, which would exacerbate the dehydration rather than serving as a compensatory mechanism.

Choice D rationale

Dehydration typically causes an increase in hematocrit, not a decrease. Hematocrit is the ratio of the volume of red blood cells to the total volume of blood. When the plasma volume decreases due to water loss, the concentration of red blood cells becomes relatively higher, a condition called hemoconcentration. A decreased hematocrit would suggest anemia or fluid overload. Therefore, an elevated hematocrit level is a common laboratory finding that reflects the state of fluid volume deficit in the body.

Choice A rationale

The most serious and life-threatening complication of hyperkalemia is the development of cardiac dysrhythmias. Potassium is vital for maintaining the resting membrane potential of cardiac myocytes. When serum levels exceed 5.0 mEq/L, the heart becomes hyper-excitable, leading to changes such as peaked T waves, widened QRS complexes, and potentially progressing to ventricular fibrillation or asystole. Because these rhythm disturbances can cause sudden cardiac arrest, they represent the most critical risk associated with elevated potassium.

Choice B rationale

Oliguria, which is a urine output of less than 400 mL per day, is often a cause of hyperkalemia rather than a complication of it. In many cases, hyperkalemia develops because the kidneys are failing to produce enough urine to excrete potassium. While decreased urine output is a sign of renal dysfunction that needs to be addressed, it does not carry the same immediate, fatal risk as the cardiac instability caused by high extracellular potassium levels affecting the heart.

Choice C rationale

Paresthesias, or sensations of tingling and numbness, are common neurological symptoms of hyperkalemia. They occur because the elevated potassium levels affect the excitability and conduction of peripheral nerves. While uncomfortable and an important clinical sign for the nurse or physician to monitor, paresthesias are not inherently life-threatening. They serve as a warning sign that potassium levels are high, but they do not cause the acute physiological collapse seen with cardiac complications.

Choice D rationale

Muscle weakness is a frequent manifestation of hyperkalemia as the abnormal potassium gradient interferes with the ability of muscles to repolarize and contract effectively. In severe cases, this can lead to flaccid paralysis. While profound muscle weakness can involve the respiratory muscles and lead to breathing difficulties, the immediate risk of death from a sudden cardiac arrhythmia usually precedes the onset of fatal respiratory failure, making the cardiac effects the most serious complication.