[Effect of carbachol on intestinal mucosa blood flow and absorption rate of glucose-electrolyte solution during enteral resuscitation for 50% total body surface area full-thickness burn injury in dog].

OBJECTIVE

To investigate the effect of carbachol (CAR) on blood flow of intestinal mucosa and absorption rate of glucose-electrolyte solution (GES) during enteral resuscitation of burn shock in dog.

METHODS

Eighteen male Beagle dogs were subjected to a (51.2+/-2.6)% total body surface area (TBSA) full-thickness flame injury, and fluid resuscitation was given according to Parkland formula 0.5 hour after burn. Animals were randomly divided into intravenous infusion of GES group (VGES group, n=6), enteral infusion of GES group (EGES group, n=6) and EGES containing 0.25 microg/kg of CAR group (EGES/CAR group n=6). In the first 8 hours post burn, intestinal absorption rate of water and Na+, intestinal mucosa blood flow (IBF), the plasma volume (PV) and plasma concentration of Na+ were continuously determined without anesthesia. At the end of 8 hours animals were sacrificed, and specimens of gut tissue were taken to determine the activity of Na+-K+-ATPase.

RESULTS

The intestinal absorption rate of water and Na+ was reduced markedly after burn in two enteral resuscitation groups and much lower than pre-injury levels and the expected infusing rate according to Parkland formula. It was found that the absorption rate of water and Na+ from 1.5 hours and 2.5 hours in EGES/CAR group were significantly higher compared with those in EGES group (all P<0.05). During 8 hours after burn, only 47.1% and 63.8% of fluids enterally infused in EGES and EGES/CAR groups were absorbed by the gut. The volume of fluid absorbed and the fluid absorption rate were significantly higher in EGES/CAR group than those in EGES group (P<0.05). Incidence of gut intolerance (diarrhea) was 83% in EGES group, which was higher than that of in EGES/CAR group (50%). IBF was significantly decreased compared with pre-injury levels in all groups. Enteral infusion of CAR led to a significant elevation of IBF in EGES/CAR compared with GES group from 4 hours after burn, but it was still lower than pre-injury levels and those in VGES group. The Na+-K+-ATPase activity between three groups ranked as follows: VGES group>EGES/CAR group>EGES group (P<0.05). Within 8 hours post injury, PV and plasma concentration of Na+ in two enteral resuscitation groups were much lower than those in VGES group, but from 4 hours after burn the values in EGES/CAR group were higher than those in EGES group (all P<0.05).

CONCLUSION

50%TBSA full-thickness flame injury led to a markedly decrease in intestinal absorption rate of water and Na+. The total volume of fluid absorbed by intestine in 8 hours was significantly lower in enteral resuscitation groups compared to the regime of the Parkland formula. CAR promoted intestinal absorption rate and PV by increasing the intestinal blood flow and Na+-K+-ATPase activity, and it seems to exert a helpful effect on the resuscitation of burn shock with electrolyte solution per oral route.