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

BACKGROUND

Fluid resuscitation is critical in patients with acute pancreatitis (AP) but there is no consensus regarding the amount of fluid to be infused. This is primarily due to difficulty in assessing the fluid deficit accurately. Our objective was to measure the amount of fluid sequestration and intravascular plasma volume deficit by measuring fluid in various body compartments in patients with AP.

METHODS

Patients with predicted severe AP presenting within 72 h of onset of pain were included prospectively. These patients underwent analysis of the body fluid composition (distribution of fluid in different compartments) by the Body Composition Monitor, a whole-body multifrequency bioimpedance analysis device. Total body water (TBW), intracellular fluid (ICF), and extracellular fluid (ECF) were measured. Intravascular plasma volume was measured objectively by 51Chromium radio-isotope labelled RBCs dilution method. Fluid sequestration in the interstitial compartment was calculated based on the fluid distribution.

RESULTS

Twenty patients with predicted severe AP were included in the study [median age 37 years, 75 % male]. The median measured ECF was 13.8 (9.9-18.8) L [58.6 % increase], ICF was 16.3 (10.4-23.3) L [20.1 % decrease], and interstitial fluid volume was 12.7 (8.9-16.3) L [101 % increase] at 48 h after hospitalization. The median plasma volume was 1.4 (0.5-2.3) L at 48 h as compared to 2.4 (1.6-3.1) L at baseline i.e. 48.6 % decrease with a plasma volume deficit of 1.1 (0.4-2.0) L. Fluid sequestration was 2.5 (1.2-3.7) L as per bioimpedance method.

CONCLUSION

The objective measurement of fluid distribution in body compartments revealed a modest plasma volume deficit in AP, supporting the rationale behind moderate fluid therapy to replenish the plasma volume deficit, rather than the total fluid sequestered in the interstitium.