Fluid Therapy in the Critically Ill
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Direct answer
Balanced crystalloids — Ringer's lactate or Plasma-Lyte — given in boluses only when the patient demonstrates fluid responsiveness, are the default fluid strategy in critical care; 30 mL/kg remains the opening dose in septic shock, after which every additional millilitre is a drug with a titration, an indication and a stopping rule. Hydroxyethyl starches are contraindicated, albumin has narrow specific indications, and positive cumulative fluid balance is treated as a toxic exposure to be reversed once shock resolves.
What you must remember
- SMART and BaSICS fixed the saline-versus-balanced question: balanced crystalloids modestly reduce major adverse kidney events, so they are the default; saline remains acceptable when chloride-loading is intended, as in hyponatraemia or metabolic alkalosis.
- Starches (HES 130/0.4) increase renal replacement therapy and, in sepsis, mortality (VISEP, 6S, CHEST) — the single most quotable contraindication in fluid therapy.
- SAFE established 4 per cent albumin as equivalent to saline for resuscitation; albumin earns specific roles in septic shock requiring large volumes, cirrhosis with spontaneous bacterial peritonitis (1.5 g/kg then 1 g/kg), and hepatorenal syndrome with terlipressin.
- The ROSE framework: rescue (life-saving boluses), optimisation (responsiveness-guided aliquots), stabilisation (maintenance only), and escalation-to-de-escalation (active fluid removal by diuretics or filtration).
- Maintenance prescription for a stable ICU patient: roughly 25 to 30 mL/kg per day of water, about 1 mmol/kg per day each of sodium and potassium, and 2 to 3 g per kg per day of glucose, with balanced solutions preferred.
- Fluid responsiveness is assessed before each elective bolus by pulse pressure variation, passive leg raise or stroke volume response — never by CVP alone.
- Cumulative positive balance independently associates with worse ARDS, AKI and mortality; CLASSIC and CLOVERS together argue for neither liberal drowning nor reflexive rationing — assess, then decide.
Four phases, one patient
A 40-year-old with acute severe pancreatitis maps the whole topic. Phase one, rescue: hypotensive with lactate 6 — 30 mL/kg balanced crystalloid in the first hours is non-negotiable. Phase two, optimisation: she stabilises at MAP 68 on low norepinephrine; further 250 to 500 mL aliquots are given only when the passive leg raise shows a stroke volume rise above 10 per cent, and two non-responding trials end the volume chapter for the day. Phase three, stabilisation: the abdomen is the third space of modern textbooks' caution, but the prescription is now maintenance — 25 to 30 mL/kg per day with potassium and glucose — plus replacing measured losses. Phase four, de-escalation: by day five she is 6 litres positive, hypoxic with bilateral infiltrates; furosemide infusion or, if oliguric, ultrafiltration drives the balance negative, and oxygenation improves as EVLW falls. The teaching point is that the question changes at each phase — from "how fast" to "should I at all" to "how do I remove it" — and answering phase-four questions with phase-one instincts is how patients drown.
Where students slip
Old habits masquerade as knowledge. "Third-space replacement" with litres of saline belongs to an era before trial evidence — fixed backgrounds ignore the glycocalyx and leak. CVP-guided boluses are still written in some answer sheets and remain wrong. Lactate treated as a pure volume order forgets it is also produced aerobically in stressed cells and cleared by the liver. The Indian exam convention adds a practical twist: Ringer's lactate is often blamed for hyperkalaemia in renal failure, yet its potassium (4 mmol/L) is trivial against the acidosis it corrects — knowing that distinction scores. Finally, know what de-resuscitation means: active removal of accumulated fluid in the stabilisation-to-recovery window, a term examiners increasingly expect.
Frequently asked questions
Which crystalloid is preferred for initial resuscitation?
A balanced solution — Ringer's lactate or Plasma-Lyte — per SMART and BaSICS; normal saline when deliberate chloride loading is acceptable or intended.
Why are starches contraindicated?
HES 130/0.4 increases acute kidney injury, renal replacement therapy and, in sepsis, mortality across VISEP, 6S and CHEST.
When does albumin have a defined role?
Septic shock needing large crystalloid volumes, cirrhosis with spontaneous bacterial peritonitis, hepatorenal syndrome with terlipressin, and symptomatic hypoalbuminaemia is not one of them.
What are the ROSE phases of fluid therapy?
Rescue, optimisation, stabilisation and de-escalation (with escalation overlapping the first two) — each phase carries a different fluid question and risk.
How is fluid responsiveness assessed at the bedside?
Pulse pressure or stroke volume variation above about 10 to 13 per cent when valid, otherwise a passive leg raise with a real-time stroke volume or end-tidal CO2 response.
What is an appropriate maintenance prescription?
About 25 to 30 mL/kg per day of water with 1 mmol/kg per day each of sodium and potassium and 2 to 3 g per kg per day of glucose in a balanced crystalloid.