# Situation: A 68-year-old woman weighing 60 kg is admitted to the intensive care unit (ICU) with fever, flank pain, and confusion from an acute kidney infection. Her temperature is 39.4 °C, heart rate 124/min, respiratory rate 28/min, blood pressure 82/44 mmHg (mean arterial pressure 57 mmHg), and serum lactate 4.8 mmol/L (43 mg/dL). Two sets of blood cultures have been drawn and the first antibiotic dose has been given. The provider orders lactated Ringer's solution 30 mL/kg intravenously over 3 hours. At how many mL/h should the nurse set the infusion pump? Round off to the nearest whole number.

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> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 68-year-old woman weighing 60 kg is admitted to the intensive care unit (ICU) with fever, flank pain, and confusion from an acute kidney infection. Her temperature is 39.4 °C, heart rate 124/min, respiratory rate 28/min, blood pressure 82/44 mmHg (mean arterial pressure 57 mmHg), and serum lactate 4.8 mmol/L (43 mg/dL).

Two sets of blood cultures have been drawn and the first antibiotic dose has been given. The provider orders lactated Ringer's solution 30 mL/kg intravenously over 3 hours. At how many mL/h should the nurse set the infusion pump? Round off to the nearest whole number.

## 보기

1. 10 mL/h
2. 400 mL/h
3. 600 mL/h **✔ 정답**
4. 1,800 mL/h

**정답: 3**

## 해설

For sepsis-induced hypoperfusion, at least 30 mL/kg of intravenous crystalloid is given within the first 3 hours, with frequent reassessment for response and fluid overload. The total is 30 mL/kg × 60 kg = 1,800 mL, and 1,800 mL ÷ 3 hours = 600 mL/h. Balanced crystalloids such as lactated Ringer's are preferred over 0.9% saline.

## 심화 해설

The question asks for a simple infusion rate calculation, but the clinical context is a patient with sepsis-induced hypoperfusion. The calculation itself is straightforward, yet understanding why the fluid is ordered and how the rate fits into the larger resuscitation bundle is essential for nursing licensure exams.

First, confirm the patient’s weight-based fluid order. The provider prescribed lactated Ringer’s solution 30 mL/kg over 3 hours. For a 60 kg patient, the total volume is 30 mL/kg × 60 kg = 1,800 mL. Dividing by the infusion time gives 1,800 mL ÷ 3 h = 600 mL/h. The pump should be set at 600 mL/h.

This order reflects the sepsis resuscitation guideline that recommends at least 30 mL/kg of intravenous crystalloid within the first 3 hours for sepsis-induced hypoperfusion. The patient’s presentation supports this diagnosis: fever, tachycardia, tachypnea, hypotension with a mean arterial pressure of 57 mmHg, and an elevated serum lactate of 4.8 mmol/L (43 mg/dL). Lactate above 2 mmol/L with hypotension indicates inadequate tissue perfusion, which is the trigger for aggressive initial fluid resuscitation.

The choice of lactated Ringer’s over 0.9% saline is clinically meaningful. Balanced crystalloids such as lactated Ringer’s are preferred because their electrolyte composition more closely resembles plasma and they are associated with less hyperchloremic metabolic acidosis than normal saline. The evidence base supports this preference, though it also highlights ongoing debate about whether a fixed 30 mL/kg approach is optimal for every patient.

A cohort study by Munroe et al. examined whether 30 mL/kg or more of fluid within 6 hours was associated with 30-day mortality in community-onset sepsis, specifically questioning benefit in patients with severe cardiac or kidney comorbidities or intermediate lactate elevation (18.0–36.0 mg/dL) [1]. This reminds the nurse that while the initial order is standardized, ongoing reassessment is required because fluid responsiveness varies. A meta-analysis by Nagy et al. compared fixed-volume versus personalized fluid resuscitation and suggested that individualized strategies may reduce mortality in septic shock, though the evidence is not yet definitive . The narrative review by Mansoor et al. describes the evolution from early goal-directed therapy toward more personalized resuscitation, emphasizing that protocolized initial fluids remain a cornerstone but must be paired with dynamic reassessment . Huang and Zou’s retrospective study specifically examined timing of lactated Ringer’s administration relative to Sepsis-3 diagnosis and found that timing may influence 28-day mortality, reinforcing that early administration is important .

For nursing practice, the calculation is only the first step. The nurse must monitor for both under-resuscitation and fluid overload during and after the 600 mL/h infusion. Reassessment includes repeat lactate, urine output, blood pressure, lung sounds, and signs of pulmonary edema, especially in an older adult with possible cardiac or renal limitations.

| Parameter | Finding | Clinical significance |
| --- | --- | --- |
| Mean arterial pressure | 57 mmHg | Below target of 65 mmHg; indicates hypoperfusion |
| Serum lactate | 4.8 mmol/L (43 mg/dL) | Above 2 mmol/L; marker of tissue hypoxia |
| Initial fluid | 30 mL/kg over 3 hours | Minimum recommended crystalloid for sepsis-induced hypoperfusion |
| Infusion rate | 600 mL/h | Calculated from total volume divided by time |

Watch out! The 30 mL/kg bolus is a starting point, not a fixed endpoint. The nurse must reassess fluid responsiveness frequently because patients with heart failure or chronic kidney disease may not tolerate the full volume without pulmonary edema. Key point! The infusion pump is set at 600 mL/h for a 60 kg patient receiving 30 mL/kg over 3 hours, and lactated Ringer’s is preferred over normal saline for sepsis resuscitation.References (research sources)

- [1]Comorbidities, Weight-Based Initial Fluid Resuscitation, and Mortality in Patients With Sepsis.Research articleMunroe ES, Walzl E, Seelye S, Cahill M, Czilok T, Jones J, Kenes MT, Posa PJ, Parks Taylor S, Prescott HC. (2026) · DOI: 10.1001/jamanetworkopen.2026.18232

## 임상 시나리오

Sepsis Fluid Resuscitation: Rate CalculationWeight-based crystalloid bolus within the first 3 hours
For sepsis-induced hypoperfusion, administer at least 30 mL/kg of intravenous crystalloid within the first 3 hours. For a 60 kg patient, the total volume is 1,800 mL, so the infusion pump should be set at 600 mL/h.

Recognize the clinical trigger: fever, tachycardia, tachypnea, hypotension with MAP 2 mmol/L indicate inadequate tissue perfusion requiring aggressive initial resuscitation.

Prefer balanced crystalloids such as lactated Ringer's over 0.9% saline to reduce the risk of hyperchloremic metabolic acidosis.

CautionReassess frequently for fluid responsiveness and signs of fluid overload, especially in older adults or those with heart failure or chronic kidney disease. The 30 mL/kg bolus is an initial target, not a fixed endpoint.

## 핵심 개념

- **Sepsis-induced hypoperfusion** — Inadequate tissue perfusion caused by sepsis, identified by hypotension (MAP 2 mmol/L).
- **Lactated Ringer's** — A balanced crystalloid solution with an electrolyte composition similar to plasma, preferred over 0.9% saline to reduce hyperchloremic acidosis.
- **Mean arterial pressure (MAP)** — Average arterial pressure during one cardiac cycle; target is ≥65 mmHg in septic shock.
- **Serum lactate** — A marker of tissue hypoperfusion; levels above 2 mmol/L indicate anaerobic metabolism and inadequate oxygen delivery.
- **30 mL/kg crystalloid bolus** — The minimum initial fluid volume recommended within the first 3 hours for sepsis-induced hypoperfusion or septic shock.

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