Fluid status of terminally ill cancer patients with intestinal obstruction: an exploratory observational study

Although the dehydration-rehydration problem in end-of-life care is one of the most important issues, clinical indications of hydration therapy have not been clarified because the pathophysiology is poorly understood. To explore the physiological changes of fluid status in terminally ill cancer patients, a prospective observational study was performed. We obtained 9 pairs of blood samplings from hospice inpatients with irreversible bowel obstruction who underwent two or more laboratory examinations during the admission periods. The plasma renin activity (PRA) and brain natriuretic peptide (BNP) were measured, in addition to basic laboratory tests performed as clinically required. A chart review evaluated the degree of fluid retention symptoms. In 7 patients receiving intravenous rehydration of 700-2200 ml/day, the mean PRA level significantly increased from 3.5+/-2.5 ng ml(-1) h(-1) to 11+/-8.2 ng ml(-1) x h(-1) ( P=0.047), and the mean BNP level significantly decreased from 52+/-34 pg/ml to 22+/-14 pg/ml ( P=0.047). Edema, ascites, and pleural effusion/pulmonary edema deteriorated in 5, 3, and 5 patients, respectively. In 2 patients without rehydration therapy, peripheral edema deteriorated with increased PRA levels (0.5 to 20 ng ml(-1) x h(-1), 0.4 to 8.7 ng ml(-1) x h(-1), respectively). In conclusion, intravenous volume depletion with fluid retention symptoms was observed in terminally ill cancer patients with intestinal obstruction both receiving and not receiving intravenous hydration. The pathological mechanism hypothesized is the fluid shift from the intravascular compartment to the interstitial spaces.