Renal, Fluids, Electrolytes & Acid-Base · Topic 9 of 22

IV Fluid Therapy & Fluid Responsiveness

Fluids & electrolytes · resuscitation

IV Fluid Therapy & Fluid Responsiveness

Resuscitate with crystalloid — balanced over saline — then give more only when a dynamic test shows the patient is fluid responsive.

Key numbers

Sepsis: 30 mL/kg crystalloid in 3 hours30 mL/kg in 3 h

Passive leg raise: CO up ≥ 10%CO ↑ ≥ 10%

PPV over 12% only in ventilated patientsPPV > 12%

Reassess urine output, capillary refill, lactateUO > 0.5 mL/kg/h

01 · The numberSepsis: 30 mL/kg crystalloid in 3 hours

For sepsis-induced hypoperfusion or septic shock, give at least 30 mL/kg of IV crystalloid within the first 3 hours, individualized to the patient; dose by adjusted or ideal weight when BMI > 30.

02 · GiveBalanced crystalloids over 0.9% saline

Crystalloids are the first-line resuscitation fluid; for initial resuscitation in sepsis, use balanced crystalloids (lactated Ringer's, Plasma-Lyte) rather than 0.9% saline.

03 · Defined byPassive leg raise: CO up ≥ 10%

Passive leg raising is a reversible preload challenge of about 300 mL of blood; a rise in directly measured cardiac output or stroke volume of 10% or more predicts fluid responsiveness without giving fluid.

The rules

Know these

Guide further fluid with dynamic measures must knowAfter the initial bolus, guide fluid with dynamic measures — passive leg raise or a bolus with stroke volume, stroke volume or pulse pressure variation — not examination or static values like CVP.

No hypotonic fluids for resuscitationHypotonic fluids (0.45% saline, D5W) stay intravascular even less than isotonic fluid and are never used for resuscitation; they replace a free-water deficit.

Diagnosis & monitoring

Work-up

PPV over 12% only in ventilated patientsPulse pressure variation above about 12% predicts fluid responsiveness only in passively ventilated patients in sinus rhythm with adequate tidal volume — not with spontaneous breathing, arrhythmia or low lung compliance.

Reassess urine output, capillary refill, lactateReassess perfusion after each bolus: urine output above 0.5 mL/kg/h, capillary refill time and lactate trend; do not keep giving fluid just to normalize lactate.

Do right now

In this order

First moves

Sepsis: 30 mL/kg crystalloid in 3 hours30 mL/kg in 3 h

→

Guide further fluid with dynamic measures

→

Reassess urine output, capillary refill, lactateUO > 0.5 mL/kg/h

Why each step

Sepsis: 30 mL/kg crystalloid in 3 hoursFor sepsis-induced hypoperfusion or septic shock, give at least 30 mL/kg of IV crystalloid within the first 3 hours, individualized to the patient; dose by adjusted or ideal weight when BMI > 30.

Guide further fluid with dynamic measuresAfter the initial bolus, guide fluid with dynamic measures — passive leg raise or a bolus with stroke volume, stroke volume or pulse pressure variation — not examination or static values like CVP.

Management

Orders

Albumin only after large crystalloid volumesUse crystalloids alone rather than adding albumin routinely; supplemental albumin may be appropriate after large crystalloid volumes or in cirrhosis.

Bolus 1 L and reassess; caution cardiogenic shockIn hypovolemic shock give 1 L of crystalloid rapidly and reassess; large rapid boluses are usually contraindicated in cardiogenic and obstructive shock.

Persistent hypotension after bolus: start vasopressorsIf sepsis-induced hypotension persists after the initial crystalloid bolus, add vasopressors; in unstable shock start them alongside fluid. After 30 mL/kg, a liberal or restrictive strategy is acceptable.

Red flags & don'ts

Avoid harm

Traumatic brain injury: 0.9% saline, no albumin avoidIn traumatic brain injury use 0.9% saline rather than balanced fluid, and avoid albumin, which was associated with higher mortality in TBI.

Never use hydroxyethyl starch for resuscitation avoidDo not resuscitate with hydroxyethyl starch (strong recommendation: more kidney injury, renal replacement therapy and death) and avoid gelatin.

Saline causes hyperchloremic metabolic acidosis complicationLarge volumes of 0.9% saline cause hyperchloremic metabolic acidosis and renal vasoconstriction; in the SMART trial's sepsis subgroup, balanced solutions lowered 30-day mortality.

Fluid overload: pulmonary edema, compartment syndrome complicationExcess or too-rapid fluid causes pulmonary edema, worsens ARDS and can precipitate abdominal or extremity compartment syndrome.

Balanced crystalloid or 0.9% saline?

Commonly confused

Sepsis resuscitation	Preferred
Traumatic brain injury	Not preferred
Acid–base effect	Less hyperchloremic acidosis
Outcome signal	Lower mortality in sepsis subgroup (SMART)

Commonly confused

Tell apart

CVP does not predict fluid responsivenessStatic markers — CVP, heart rate and blood pressure — are poor guides to fluid responsiveness; a single CVP value should not decide whether to give fluid.

Hemorrhage needs blood, not more crystalloidIn severe hemorrhagic shock replace volume with blood products (plasma, platelets and red cells about 1:1:1) rather than more crystalloid.

More detail

Reference

Show 4 reference facts

Only about 15–25% of an infused isotonic crystalloid remains intravascular once it redistributes; the rest moves to the interstitium.

Other dynamic tests: end-expiratory occlusion in ventilated patients (cardiac output rise ≥ 5%) and a 100-mL mini-fluid challenge; a conventional 500-mL challenge itself risks overload if repeated.

Pulse pressure variation values of 9–13% fall in a grey zone where it cannot reliably classify fluid responsiveness.

A sick patient with CVP < 3 mmHg is presumed volume depleted, and CVP above 12–15 mmHg suggests hypovolemia is not the only cause of hypoperfusion — but CVP is often unreliable.

Pearl

Fluid is a drug: after the initial bolus, test before you give — a passive leg raise costs no fluid.

Sources · Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2026 — SCCM recommendations page · Guideline Central — 2026 SCCM/ESICM Sepsis Guideline: key changes from 2021 · Evans L et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021. Intensive Care Med 2021;47:1181–1247 · Monnet X, Marik PE, Teboul JL. Prediction of fluid responsiveness: an update. Ann Intensive Care 2016;6:111 · Merck Manual Professional — Intravenous Fluid Resuscitation (2026) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).