Order: Dobutamine 2 mcg/kg/min for a client who weighs 154 lb. Available: Dobutamine 250 mg in 250 ml DSW. Calculate the rate in ml/hr required to infuse 2 mcg/kg/min:

Rationale:

1. 2 mm Hg – Far too low and does not match the calculation.
2. 90 mm Hg –Matches the calculation (MAP − ICP).

Given:

• MAP = 108 mm Hg
• ICP = 18 mm Hg

Calculation:
CPP = 108 − 18
CPP = 90 mm Hg

A CPP of 70–100 mm Hg is generally considered adequate to maintain cerebral perfusion in adults. Values below 60 mm Hg can result in cerebral ischemia

C. 126 mm Hg – This would be MAP + ICP, which is not correct for CPP.
D. 54 mm Hg – Likely results from an incorrect calculation.
Cerebral perfusion pressure (CPP) is calculated using the formula: CPP = MAP − ICP.

Rationale:
A. Excess glucose in the circulating blood is correct because critical illness triggers a stress response mediated by hormones such as cortisol, catecholamines (epinephrine and norepinephrine), and glucagon. These hormones stimulate gluconeogenesis, glycogenolysis, and insulin resistance, leading to hyperglycemia. This is part of the body’s adaptive “fight or flight” response to provide energy for vital organs, but persistent hyperglycemia can contribute to complications such as infection, delayed wound healing, and organ dysfunction.

B. Negative feedback system is reversed is incorrect because the body’s feedback mechanisms are not literally reversed; rather, stress hormones override normal homeostatic regulation, leading to temporary dysregulation of processes like glucose metabolism.

C. Homeostasis is maintained is incorrect because critical illness disrupts homeostasis. The stress response creates a hypermetabolic state, fluid and electrolyte shifts, hormonal changes, and immune activation, all of which temporarily alter normal physiologic balance.

D. Decrease glucose in the circulating blood is incorrect because, in critical illness, stress-induced hormonal responses increase glucose levels rather than decrease them. Hypoglycemia is less common and usually occurs only with specific interventions or underlying conditions.