**Question:** Which of the following is first line vasopressor in case of cardiogenic shock?

A. Norepinephrine
B. Epinephrine
C. Phenylephrine
D. Vasopressin

**Core Concept:** Vasopressors are medications used to increase blood pressure by constricting blood vessels, ensuring adequate perfusion to vital organs. Cardiogenic shock occurs when the heart is unable to pump blood efficiently, leading to low blood pressure.

**Why the Correct Answer is Right:** Norepinephrine (A) is a first-line vasopressor in cardiogenic shock because it has a wide range of effects on different types of vascular beds, including the peripheral, coronary, and cerebral circulation. Norepinephrine increases heart rate, cardiac output, and systemic vascular resistance, thereby improving blood pressure and perfusion to vital organs.

**Why Each Wrong Option is Inaccurate:**

B. Epinephrine: While epinephrine (B) has similar effects as norepinephrine, it has a much shorter half-life and may cause more severe tachycardia and arrhythmias, making it less suitable for long-term use in cardiogenic shock.

C. Phenylephrine (C): Phenylephrine is a selective alpha-1 agonist, causing peripheral vasoconstriction but does not increase cardiac output directly. In cardiogenic shock, the primary goal is to improve cardiac output, making phenylephrine an inadequate choice.

D. Vasopressin (D): Vasopressin (also known as antidiuretic hormone) primarily acts on renal vasculature and does not significantly affect systemic vascular resistance or cardiac output. It is less effective in increasing blood pressure compared to norepinephrine in cases of cardiogenic shock.

**Clinical Pearl:** In cases of cardiogenic shock, the primary goal is to improve cardiac output and systemic vascular resistance, which norepinephrine achieves effectively due to its extensive vascular targeting. The other options do not achieve this goal as efficiently and may cause undesirable side effects.