A pt is brought to the emergency as a case of head injury, following a head on collision road traffic accident. His BP is 90/60 mmHg. Tachycardia is present. Most likely diagnosis is
**Core Concept**
Shock is a clinical syndrome characterized by inadequate tissue perfusion, leading to cellular hypoxia and organ dysfunction. Hypovolemic shock, in particular, results from a decrease in effective circulating blood volume, often due to blood loss or fluid loss. In the context of head injury, this can occur due to internal bleeding or external bleeding from wounds.
**Why the Correct Answer is Right**
In this scenario, the patient's low blood pressure (90/60 mmHg), tachycardia, and head injury suggest hypovolemic shock. The likely cause is internal bleeding from the head injury, which has led to a decrease in circulating blood volume. The body's compensatory response to maintain adequate perfusion is manifest as tachycardia, an attempt to increase cardiac output. However, the blood pressure remains low, indicating inadequate perfusion.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because while hypovolemic shock is a possibility, the question stem does not provide enough information to rule out other types of shock, such as cardiogenic or distributive shock. However, given the context of head injury and hypotension, hypovolemic shock is the most likely diagnosis.
**Option B:** This choice is incorrect because while tachycardia is a component of hypovolemic shock, it is not a standalone diagnosis. Tachycardia can occur in various conditions, including anxiety, pain, or other forms of shock.
**Option C:** This choice is incorrect because while head injury can lead to a range of complications, including bleeding, the question stem specifically asks for a diagnosis based on the patient's presentation (hypotension and tachycardia). This choice is too broad and does not directly address the patient's clinical condition.
**Option D:** This choice is incorrect because while hypovolemic shock can lead to organ dysfunction, including renal failure, the question stem does not provide enough information to diagnose renal failure specifically.
**Clinical Pearl / High-Yield Fact**
In trauma patients, early recognition of hypovolemic shock is critical, as it can progress rapidly to multi-organ failure. The classic "shock index" (heart rate/systolic blood pressure) can be useful in identifying patients at risk of shock.
**Correct Answer: A. Hypovolemic shock.**