A nurse is providing care for a client following a cardiac arrest due to pulseless electrical activity (PEA). Which of the following alterations are causes of PEA? (Select All that Apply.)

A. Respiratory rate of 12/min: A respiratory rate of 12/min is within the normal adult range (12-20 breaths per minute). In the context of increased intracranial pressure (ICP), respiratory rate changes might be noted as part of the Cushing's reflex (which is characterized by bradycardia, hypertension, and abnormal respiratory patterns like Cheyne-Stokes or ataxic breathing), but a rate of 12/min on its own is not indicative of a worsening condition. However, if the patient begins to show signs of irregular or abnormal breathing patterns, this would raise concern.

B. Blood pressure of 108/74 mm Hg: This blood pressure is also within the normal range and does not suggest a worsening of intracranial pressure. In fact, ICP can lead to a rise in blood pressure (due to the body's compensatory mechanisms, known as Cushing's triad), along with bradycardia and abnormal respirations. Thus, a stable blood pressure like 108/74 mm Hg is not concerning in this context.

C. Changes to pupil size and shape: Changes in pupil size, shape, or reactivity are significant indicators of worsening intracranial pressure. Unequal pupils (anisocoria), sluggish or absent response to light, and fixed dilated pupils are signs of brainstem compression or damage, which often occur as ICP increases. This could indicate herniation or severe brain injury, which are worsening conditions.

D. Swelling of the optic nerve: Swelling of the optic nerve, or papilledema, is another important sign of increased intracranial pressure. It occurs due to increased pressure within the skull, which causes congestion and swelling of the optic disc. This finding can be seen on fundoscopy and indicates a worsening condition, as it suggests elevated pressure affecting the brain.

E. Decreasing Glasgow Coma scores: A decreasing Glasgow Coma Scale (GCS) score is a critical indicator of worsening neurologic function in a patient with increased ICP. The GCS is used to assess a patient's level of consciousness, and a decreasing score suggests that the brain's function is deteriorating. This can be caused by worsening edema, brain herniation, or other severe neurological impairments associated with elevated ICP.

Pulseless electrical activity (PEA) refers to a situation in which an electrocardiogram (ECG) shows electrical activity in the heart, but there is no effective mechanical activity and no palpable pulse. PEA can result from various underlying conditions that impair cardiac function or compromise circulation.

A. Hypertension: Hypertension, or high blood pressure, is not typically a direct cause of PEA. While uncontrolled hypertension can contribute to cardiovascular disease and increase the risk of cardiac events such as myocardial infarction, it is not a direct cause of PEA.

B. Hypovolemia: Hypovolemia, or low blood volume, is a common cause of PEA. Reduced circulating blood volume leads to decreased preload and inadequate filling of the heart chambers, impairing cardiac output. This can result in ineffective cardiac contractions and the development of PEA.

C. Hypoxia: Hypoxia, or inadequate oxygenation of tissues, is a significant cause of PEA. Insufficient oxygen delivery to the myocardium impairs cardiac function and can lead to ineffective cardiac contractions. Without adequate oxygenation, the heart is unable to generate sufficient mechanical force to maintain circulation, resulting in PEA.

D. Hyperkalemia: Hyperkalemia, or elevated levels of potassium in the blood, can cause PEA by disrupting cardiac electrical activity. Excessive potassium ions in the extracellular fluid alter the normal myocardial action potential, leading to cardiac conduction abnormalities and potential arrhythmias, including PEA.

E. Hypernatremia: Hypernatremia, or elevated levels of sodium in the blood, is not typically a direct cause of PEA. While severe hypernatremia can lead to neurological symptoms and dehydration, it does not directly impair cardiac electrical activity or mechanical function to the extent that it causes PEA.

F. Hyperthermia: Hyperthermia, or elevated body temperature, is not typically a direct cause of PEA. While extreme hyperthermia can lead to cardiovascular complications such as heat stroke, it is not a common cause of PEA unless it is associated with severe systemic metabolic derangements.