Short Answer 
Understanding the relationship between Mean Arterial Pressure (MAP), Intracranial Pressure (ICP), and Cerebral Perfusion Pressure (CPP) is essential; a calculated low CPP indicates cerebral hypoperfusion. In a patient with traumatic brain injury, hypotension may worsen as the body attempts to increase MAP to restore adequate cerebral blood flow.
Step 1: Understand Brain Pressure Dynamics
To grasp why hypotension is expected, we must first understand the interaction between Mean Arterial Pressure (MAP), Intracranial Pressure (ICP), and Cerebral Perfusion Pressure (CPP). CPP is crucial for ensuring that the brain receives adequate blood supply and is calculated using the formula: CPP = MAP ‚à à ICP. In this case, a low CPP indicates potential issues in cerebral blood flow, which is vital for the brain’s metabolism.
Step 2: Calculate and Analyze CPP
In the scenario, the patient’s MAP is 65 mm Hg, and ICP is 22 mm Hg, leading to a CPP of 43 mm Hg. This calculation suggests that the CPP is below the normal range of 50-70 mm Hg, which is a clear sign of cerebral hypoperfusion. This condition means that the brain is not receiving sufficient blood flow, prompting the body to respond by attempting to raise blood pressure to improve CPP and restore adequate cerebral blood flow.
Step 3: Implications of Hypotension in the Context
Given the calculated low CPP, the anticipated finding in this patient with a traumatic brain injury is that hypotension may continue or worsen. Although the question’s context implies hypotension is already present, the underlying physiological response to low CPP indicates that the body will strive to increase MAP as a compensatory mechanism. Other options, such as widening pulse pressure, tachycardia, or increased respiratory effort, are not directly tied to the observed MAP and ICP values and illustrate how important monitoring these parameters is for patient management.