Objective measurement of plasma fluid deficit, sequestration and redistribution of fluid in body compartments in patients with predicted severe acute pancreatitis.

Extracellular fluid was markedly elevated in patients with predicted severe acute pancreatitis at 48 hours after hospitalization.

• Median measured ECF was 13.8 (9.9–18.8) L at 48 h, representing a 58.6% increase compared to normal reference values.
• ECF was measured using the Body Composition Monitor, a whole-body multifrequency bioimpedance analysis device.
• Study included 20 patients with predicted severe AP presenting within 72 h of onset of pain.
• Median age was 37 years, 75% male.

Intracellular fluid volume was decreased in patients with predicted severe acute pancreatitis at 48 hours.

• Median measured ICF was 16.3 (10.4–23.3) L at 48 h, representing a 20.1% decrease compared to normal reference values.
• ICF was measured using whole-body multifrequency bioimpedance analysis.
• The decrease in ICF contrasted with the substantial increase in ECF, suggesting fluid shift from intracellular to extracellular compartment.

Interstitial fluid volume was more than doubled in patients with predicted severe acute pancreatitis at 48 hours.

• Median interstitial fluid volume was 12.7 (8.9–16.3) L at 48 h, representing a 101% increase.
• Interstitial fluid sequestration was calculated based on the fluid distribution measured by bioimpedance.
• Fluid sequestration in the interstitial compartment was 2.5 (1.2–3.7) L as per the bioimpedance method.

Intravascular plasma volume was substantially reduced at 48 hours compared to baseline in patients with predicted severe acute pancreatitis.

• Median plasma volume was 1.4 (0.5–2.3) L at 48 h compared to 2.4 (1.6–3.1) L at baseline, representing a 48.6% decrease.
• The plasma volume deficit was 1.1 (0.4–2.0) L.
• Plasma volume was measured objectively using the 51Chromium radio-isotope labelled RBC dilution method.
• Despite large interstitial fluid sequestration of 2.5 L, the intravascular plasma volume deficit was only approximately 1.1 L.

The plasma volume deficit in acute pancreatitis was modest relative to the total interstitial fluid sequestration, supporting moderate rather than aggressive fluid resuscitation.

• Plasma volume deficit of 1.1 (0.4–2.0) L was substantially less than the 2.5 (1.2–3.7) L of fluid sequestered in the interstitium.
• The authors concluded that fluid therapy should aim to replenish the plasma volume deficit rather than the total fluid sequestered in the interstitium.
• The findings provide objective measurement-based rationale for moderate fluid therapy in predicted severe AP.

Total body water distribution shifts were characterized by movement of fluid from the intracellular to the extracellular and interstitial compartments in acute pancreatitis.

• ECF increased by 58.6% while ICF decreased by 20.1%, and interstitial fluid increased by 101%.
• Total body water, intracellular fluid, and extracellular fluid were all measured using the Body Composition Monitor (whole-body multifrequency bioimpedance analysis).
• Measurements were taken at 48 h after hospitalization in patients presenting within 72 h of pain onset.