A nurse is caring for a client who has a subarachnoid hemorrhage and asks why they are having a CT angiography. Which of the following should the nurse understand about CT angiography?

Tonometer intraocular pressure reading 8 mm Hg (Option A): A low intraocular pressure reading may indicate a detached retina. In a detached retina, the vitreous humor (gel-like substance in the eye) may leak into the space behind the retina, causing a decrease in intraocular pressure. However, it's important to note that intraocular pressure alone cannot definitively diagnose a detached retina, and further diagnostic tests, such as a dilated eye examination or retinal imaging, would be needed for confirmation.

Smooth retina edges identified on slit-lamp biomicroscope examination (Option B): In the case of a detached retina, the edges of the retina may appear irregular or undulating rather than smooth. This irregularity is often observed during a dilated eye examination rather than with a slit-lamp biomicroscope.

Visual acuity of 20/20 using the Snellen eye chart (Option C): Visual acuity may be affected in a detached retina, depending on the extent and location of the detachment. However, visual acuity alone cannot confirm a detached retina, as other factors such as refractive errors or cataracts can also affect visual acuity.

Lens and cornea appear intact during ophthalmoscope exam (Option D): While a detached retina may be visualized during an ophthalmoscope examination as a gray or whitish area behind the lens, the appearance of the lens and cornea being intact does not definitively diagnose a detached retina. A thorough dilated eye examination by an ophthalmologist is necessary for accurate diagnosis.

A. Creatine kinase (CK) test: While creatine kinase isoenzymes, including CK-MB, can be elevated following myocardial infarction (MI), they are not specific to cardiac muscle injury. CK is found in various tissues throughout the body, so elevated levels can also indicate damage to skeletal muscle or brain tissue, among other sources.

B. Creatine kinase-myocardial band (CK-MB) test: CK-MB is a cardiac-specific isoform of creatine kinase, and elevated levels can indicate myocardial injury, particularly in the context of an acute MI. However, troponin T is a more sensitive and specific marker for myocardial injury.

C. Brain natriuretic peptide (BNP) test: Brain natriuretic peptide is primarily used in the diagnosis and management of heart failure. While elevated BNP levels can indicate heart muscle strain or stress, they are not specific markers for acute myocardial infarction or early injury to the cardiac muscle.

D. Troponin T test: This is the correct answer. Troponin T is a highly specific marker for cardiac muscle injury. Elevated troponin levels can be detected within hours of myocardial infarction and persist for several days, making it an essential tool in the diagnosis of acute coronary syndromes, including myocardial infarction. Troponin T is considered one of the gold standard biomarkers for detecting early injury to the cardiac muscle.