# Situation: A 58-year-old woman weighing 68 kg is brought to the emergency department with fever, flank pain, and new confusion. A urinary source of infection is suspected. She has no history of heart failure or kidney disease and no known drug allergies. The full 30 mL/kg crystalloid volume has been infused and antimicrobials have been given. Her findings now are: Blood pressure: 84/46 mmHg Heart rate: 116/min Serum lactate: 3.8 mmol/L (normal < 2 mmol/L) Urine output: 20 mL in the past hour Which conclusion should guide the next orders?

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> subject: Nursing Practice V — Care of Clients with Maladaptive Patterns of Behavior; Care of Clients with Life-Threatening Conditions, Acute Multi-Organ Problems, High Acuity and Emergency Situations

## 문제

Situation: A 58-year-old woman weighing 68 kg is brought to the emergency department with fever, flank pain, and new confusion. A urinary source of infection is suspected. She has no history of heart failure or kidney disease and no known drug allergies.

The full 30 mL/kg crystalloid volume has been infused and antimicrobials have been given. Her findings now are:
Blood pressure: 84/46 mmHg
Heart rate: 116/min
Serum lactate: 3.8 mmol/L (normal < 2 mmol/L)
Urine output: 20 mL in the past hour
Which conclusion should guide the next orders?

## 보기

1. Sepsis without shock, since the systolic pressure is still above 80 mmHg
2. Adequate resuscitation, since the lactate level is now below 4 mmol/L
3. Septic shock, which calls for a vasopressor to raise perfusion pressure **✔ 정답**
4. Persistent hypoperfusion that calls for a second 30 mL/kg fluid bolus

**정답: 3**

## 해설

Her mean arterial pressure is (84 + 2 × 46) ÷ 3 ≈ 59 mmHg, below the usual target of 65 mmHg, and lactate stays above 2 mmol/L after adequate fluids. Needing a vasopressor to hold a mean arterial pressure of at least 65 mmHg with lactate above 2 mmol/L despite fluids defines septic shock. Urine output of 20 mL/hour is also below 0.5 mL/kg/hour (34 mL/hour).

## 심화 해설

Clinical situation A 58-year-old woman with suspected urosepsis has completed the initial 30 mL/kg crystalloid bolus and received antimicrobials. Her current blood pressure is 84/46 mmHg, heart rate 116/min, serum lactate 3.8 mmol/L, and urine output 20 mL/hour. The question asks which conclusion should guide the next set of orders.

Step 1: Calculate the mean arterial pressure (MAP)

MAP is estimated as (systolic + 2 × diastolic) ÷ 3. For this patient, that is (84 + 2 × 46) ÷ 3, which equals approximately 59 mmHg. The resuscitation target for most patients with sepsis is a MAP of at least 65 mmHg. A MAP below this threshold indicates that perfusion pressure to vital organs is inadequate, even if the systolic pressure alone remains above 80 mmHg. Blood pressure should never be interpreted using only the systolic number when MAP is the hemodynamic variable that determines organ perfusion.

Step 2: Interpret the lactate level

Serum lactate is a marker of tissue hypoperfusion and anaerobic metabolism. The normal value is below 2 mmol/L. This patient’s lactate remains elevated at 3.8 mmol/L after the full crystalloid volume has been infused. A lactate above 2 mmol/L that persists despite adequate fluid resuscitation is a defining feature of septic shock, not simply sepsis without shock. The fact that the lactate is below 4 mmol/L does not mean resuscitation is complete; the threshold for abnormality is 2 mmol/L, and any value above that is clinically significant in this context.

Step 3: Apply the definition of septic shock

According to the current standard of care, septic shock is defined by three simultaneous criteria: persistent hypotension despite fluid resuscitation, a serum lactate greater than 2 mmol/L, and the need for a vasopressor infusion to maintain a MAP of at least 65 mmHg. This patient meets all three criteria. Her MAP is below 65 mmHg, her lactate is above 2 mmol/L, and she has already received the initial fluid bolus without achieving hemodynamic stability. The presence of these three findings together means the next step is to initiate a vasopressor, most commonly norepinephrine, to raise perfusion pressure.

Step 4: Evaluate urine output as a perfusion marker

Urine output is a direct indicator of renal perfusion. The expected minimum is 0.5 mL/kg/hour. For a 68 kg patient, that threshold is 34 mL/hour. Her actual output of 20 mL/hour is below this target, confirming that end-organ perfusion remains compromised. This finding reinforces the conclusion that the patient is in septic shock and needs vasopressor support rather than additional fluid alone.

Why not the other options?

Option 1 is incorrect because septic shock is not excluded by a systolic pressure above 80 mmHg. The MAP, not the systolic value, is the hemodynamic target, and her MAP of 59 mmHg is clearly inadequate. Option 2 is incorrect because the lactate threshold for abnormality is 2 mmol/L, not 4 mmol/L. A lactate of 3.8 mmol/L is still elevated and indicates ongoing hypoperfusion. Option 4 is incorrect because the patient has already received the full 30 mL/kg crystalloid volume. Watch out! Administering a second large fluid bolus without vasopressor support can worsen outcomes by causing fluid overload, pulmonary edema, and further hemodynamic instability. In septic shock, vasopressors are started when fluids alone fail to restore adequate perfusion pressure.

Clinical reasoning summary

The sequence of assessment is: calculate MAP, check lactate, evaluate urine output, and then determine whether the patient meets the septic shock definition. This patient has a MAP below 65 mmHg, lactate above 2 mmol/L, and oliguria despite adequate initial fluid resuscitation. The correct conclusion is septic shock, and the next order should be a vasopressor to raise MAP to at least 65 mmHg. Key point! The defining triad of septic shock is persistent hypotension after fluids, lactate above 2 mmol/L, and the requirement for vasopressor support to maintain a MAP of 65 mmHg or higher.

## 임상 시나리오

Septic Shock Recognition After Fluid ResuscitationMAP and lactate guide vasopressor initiation
Calculate MAP as (SBP + 2×DBP)/3. A value below 65 mmHg indicates inadequate perfusion pressure, regardless of systolic pressure.

Persistent lactate above 2 mmol/L after 30 mL/kg crystalloid defines septic shock, not sepsis without shock.

Start a vasopressor such as norepinephrine to achieve MAP ≥65 mmHg; do not give additional fluid boluses routinely.

CautionUrine output below 0.5 mL/kg/hr confirms hypoperfusion. A second fluid bolus risks volume overload without correcting vasoplegia.

## 핵심 개념

- **Mean arterial pressure (MAP)** — Average arterial pressure during one cardiac cycle, estimated as (SBP + 2×DBP)/3; target ≥65 mmHg in sepsis.
- **Septic shock** — Sepsis with persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg and lactate >2 mmol/L despite adequate fluids.
- **Lactate** — Marker of tissue hypoperfusion; normal
- **Vasopressor** — Agent such as norepinephrine that raises blood pressure by increasing systemic vascular resistance.
- **Fluid resuscitation** — Initial 30 mL/kg crystalloid bolus for sepsis-induced hypoperfusion or septic shock.

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