Experimental antegrade enema. Effects on water, electrolyte and acid-base balances with different solutions.

Purpose: To study the effects on the water, electrolyte, and acid-base balances in rabbits submitted to antegrade enema with different solutions through appendicostomy.

Methods: Forty male New Zealand rabbits were submitted to appendicostomy, and distributed in 4 groups, according to the antegrade enema solution: PEG group, polyethylene glycol electrolyte solution (n=10); ISS group, isotonic saline solution (n=10); GS group, glycerin solution (n=10); SPS group, sodium phosphate solution (n=10). After being weighed, arterial blood gas analysis, red blood count, creatinine and electrolytes were measured at 4 times: preoperatively (T1); day 6 postop, before enema (T2); 4h after enema (T3); and 24h after T3 (T4).

Results: In PEG group occurred Na retention after 4h, causing alkalemia, sustained for 24h with HCO3 retention. In ISS group occurred isotonic water retention and hyperchloremic acidosis after 4h, which was partially compensated in 24h. GS group showed metabolic acidosis after 4h, compensated in 24h. In SPS group occurred hypernatremic dehydration, metabolic acidosis in 4h, and hypokalemia, hypocalcemia, hypomagnesemia, and metabolic alkalosis with partially compensated dehydration in 24h.

Conclusions: All solutions used in this study caused minor alterations on water, electrolyte or acid-base balances. The most intense ones were caused by hypertonic sodium phosphate solution (SPS) and isotonic saline solution (ISS) and the least by polyethyleneglycol electrolyte solution (PEG) and glycerin solution 12% (GS).