The emergency department nurse evaluates that fluid resuscitation for a 70 kg patient in shock is effective by finding which one of the following?

1. Doseinmcg/min=2mcg/kg/min×60kg=120mcg/min

   Convert this to mg/min since the concentration is in mg:

   120mcg/min=0.12mg/min120 \text{ mcg/min} = 0.12 \text{ mg/min}120mcg/min=0.12mg/min

2. Determine the concentration of Dopamine:

   • Total amount of Dopamine: 200 mg in 250 mL of saline
   • Concentration:

   Concentration=200mg250mL=0.8mg/mL\text{Concentration} = \frac{200 \text{ mg}}{250 \text{ mL}} = 0.8 \text{ mg/mL}Concentration=250mL200mg​=0.8mg/mL

3. Calculate the pump rate in mL/min:

   To find the rate in mL/min needed to deliver 0.12 mg/min:

   Pumprate=Desireddose(mg/min)Concentration(mg/mL)\text{Pump rate} = \frac{\text{Desired dose (mg/min)}}{\text{Concentration (mg/mL)}}Pumprate=Concentration(mg/mL)Desireddose(mg/min)​

   Pumprate=0.12mg/min0.8mg/mL=0.15mL/min\text{Pump rate} = \frac{0.12 \text{ mg/min}}{0.8 \text{ mg/mL}} = 0.15 \text{ mL/min}Pumprate=0.8mg/mL0.12mg/min​=0.15mL/min

4. Convert the pump rate to mL/hour:

   Multiply by 60 to convert from mL/min to mL/hour:

   Pumprate=0.15mL/min×60min/hour=9mL/hour\text{Pump rate} = 0.15 \text{ mL/min} \times 60 \text{ min/hour} = 9 \text{ mL/hour}Pumprate=0.15mL/min×60min/hour=9mL/hour

So, you should set the pump to deliver Dopamine at a rate of 9 mL/hour.

Mean arterial pressure (MAP) is a measure of the average pressure within the arteries during one cardiac cycle. It represents the perfusion pressure that drives blood flow to organs and tissues. MAP is calculated using the formula:
MAP = Diastolic blood pressure + 1/3 (Systolic blood pressure - Diastolic blood pressure)
Blood loss, particularly in cases of significant hemorrhage, leads to a decrease in blood volume. When blood volume decreases, there is less circulating blood available to generate pressure within the arterial system. This reduction in blood volume results in decreased MAP.
Therefore, in the case of massive blood loss after trauma, the student can correlate it with a lower blood volume, which in turn leads to a lower MAP. The decrease in blood volume reduces the perfusion pressure, compromising organ and tissue perfusion
A. It causes vasoconstriction and increased MAP in (option A) is incorrect because: While vasoconstriction can occur as a compensatory mechanism to maintain blood pressure, it does not necessarily lead to an increased MAP in the context of significant blood loss.
C. It raises cardiac output and MAP in (option C) is incorrect because Blood loss typically leads to a reduction in cardiac output due to decreased blood volume. Therefore, it does not raise cardiac output and MAP.
D. There is no direct correlation to MAP in (option D) is incorrect because: There is indeed a direct correlation between blood loss and MAP. As blood volume decreases, MAP decreases as well.
Therefore, the correct correlation between blood loss and MAP is that lower blood volume lowers MAP.