Hypoalbuminemia after surgery accelerated by presence of inflammation, finds study

Circulating albumin escapes from the plasma pool at a rate of 5% per hour, corresponding to an intravascular half-life (T1/2) of 7–10 hours. This leakage is accelerated after surgery and acute inflammation and is thought to be the cause of severe disease-related hypoalbuminemia.

These considerations cast doubt on the therapeutic usefulness of 20% albumin, which is often used to expand the plasma volume in major surgery and critical care, when the endothelium glycocalyx layer is frequently harmed. Volume expansion is strongly correlated with increased albumin levels in the circulation, and thus 'leaky capillaries' may impair administered albumin's intravascular persistence. Although inflammation and major surgery enhance albumin transcapillary leakage, it is unknown if exogenous albumin likewise departs more rapidly.Recently published study has given the insight useful in clinical scenarios.

In this study, Over a 30-minute period, 70 participants received an intravenous infusion of 3 mL/kg of 20% albumin: 15 healthy volunteers, 15 post-burn patients, 15 patients who had surgery with moderate bleeding, 10 patients who underwent surgery with substantial bleeding (mean, 1.1 L), and 15 postoperative patients. Blood haemoglobin and plasma albumin were tested 15 times during a 5-hour period. The rate at which albumin degrades in the plasma was quantified using population kinetics and expressed as the half-life (T1/2).

There were no variations in T1/2 between volunteers, post-burn patients, patients who had mild bleeding during surgery, and postoperative patients. The average T1/2 was 16.2 hours, which equates to 3.8 percent of the quantity injected every hour. Two groups exhibited plasma C-reactive protein concentrations of around 60 mg/L but had a similarly long T1/2 for albumin. By contrast, patients requiring significant hemorrhage-associated surgery had a shorter T1/2, equal to 15% of the albumin administered each hour. Additionally, our results demonstrate that the T1/2 values vary significantly depending on whether plasma volume changes and blood losses are included in the computations.

The intravascular T1/2 for excess albumin is significant for the therapeutic effectiveness of a 20% albumin solution, since one gramme of albumin binds 10–11 mL of plasma water. The 20% albumin preparation contains only 5 mL of fluid per gramme albumin, implying that an infusion recruits fluid from extravascular sources to the plasma. The maximal volume expansion of plasma is roughly double the volume injected.

When albumin was administered as a 20% solution to patients with inflammation secondary to post-burn damage, to patients having surgery without severe bleeding, or to patients evaluated one day after major surgery, no faster disappearance rate was seen. Albumin administered into these conditions persisted in the plasma for the same amount of time as seen in volunteers.

Clinical relevance –

Numerous clinical scenarios previously linked with endothelial injury did not exhibit a short T1/2 for exogenous albumin. Albumin was eliminated at rates that were not statistically different from those observed in healthy volunteers throughout moderately severe inflammatory conditions, during surgery without large bleeding, and during postoperative recovery after major surgery. In comparison, surgery involving significant bleeding showed a much shorter intravascular persistence.

Reference-

Zdolsek, M., Wuethrich, P.Y., Gunnström, M. et al. Plasma disappearance rate of albumin when infused as a 20% solution. Crit Care 26, 104 (2022). https://doi.org/10.1186/s13054-022-03979-1