Convert from Fahrenheit to Celsius: 98.6

A. Myocardial contractility × myocardial blood flow: While myocardial contractility and blood flow affect cardiac output, they are not part of the formula for calculating it.

B. Ventricular filling time/diastolic filling time: This ratio does not determine cardiac output. While diastolic filling time affects stroke volume, it is not the standard formula for cardiac output.

C. Stroke volume × heart rate: Cardiac Output (CO) = Stroke Volume (SV) × Heart Rate (HR). Stroke volume is the amount of blood pumped per beat, and heart rate is the number of beats per minute. Multiplying these values gives the total volume of blood pumped per minute, making this the correct formula.

D. Preload/afterload: Preload and afterload influence cardiac function but are not used to directly calculate cardiac output.

A. Respirations: C4 injuries compromise the phrenic nerve, which controls the diaphragm. A high cervical spine injury can lead to respiratory failure, making airway and breathing the top priority.

B. Pulse: While monitoring circulation is important, breathing takes priority in a C4 injury due to the risk of respiratory paralysis.

C. Temperature: Temperature regulation may be affected due to autonomic dysfunction, but airway and breathing remain the priority.

D. Blood Pressure: While spinal cord injuries can cause neurogenic shock (low BP, bradycardia), ensuring airway and breathing comes first.