Evolution of early fluid therapy in acute pancreatitis: Balancing perfusion needs with fluid toxicity

Abstract

Hemoconcentration, vomiting, and third-space losses make early fluid administration in acute pancreatitis (AP) seem almost reflexive. The first few hours often justify this approach. What changes faster than most ward rounds capture, however, is the physiological target itself. By the time a severe case is re-examined, capillary leak and endothelial barrier injury may already be redirecting that same crystalloid into the interstitium. The first 24 hours therefore carry two opposing imperatives: Correcting hypoperfusion and recognizing the moment at which infusion becomes injury. The WATERFALL trial reframed this trade-off by counting fluid overload as a treatment effect rather than a late mishap of usual care. Aggressive hydration produced more harm without measurable clinical gain. The trial nonetheless left a familiar bedside scenario unanswered: The patient whose hematocrit refuses to fall while a new oxygen requirement appears overnight, or whose abdomen tenses while urine output drops. Such patients were too few in the trial to define a rescue rule. Endothelial injury and glycocalyx loss explain why crystalloid escapes the vessel; for the clinician, what matters is the point at which continued infusion has stopped helping. We frame this review around fluid tolerance rather than total volume. Lactated Ringer’s remains a defensible first crystalloid, though its edge over saline is clearer for inflammatory and intermediate endpoints than for harder outcomes. The bedside practice we advocate is brief, repeated reassessment—typically near the 2-hour and 6-hour marks—drawing on blood urea nitrogen trajectory, urine output, oxygenation, abdominal status, and cardiorenal reserve as a combined picture. Infusion should be slowed, paused, or redirected when tolerance markers worsen. The margin is narrowest in phenotypes that constrain the patient before AP does: Obesity, limited respiratory reserve, and prior cardiac or renal disease.

Keywords: Acute pancreatitis; Fluid therapy; Dextran; Ringer’s lactate; Randomized controlled trial; Systemic inflammatory response syndrome; C-reactive protein

Core Tip: In early acute pancreatitis, fluid is usually started for the right reason—and continued for the wrong one. The same admission order may persist while the patient underneath it has changed. A patient with persistent hemoconcentration or oliguria may still appear under-resuscitated, but a new oxygen requirement, basal crackles, or a tense abdomen should interrupt the next bolus, not justify it. The bedside question shifts from “Is perfusion adequate?” to “Can this patient still tolerate volume?”—and the answer rarely comes from a single number. Our argument is simple: Reassess early, adjust by tolerance, and resist the inertia of the admission prescription.