OBJECTIVETo investigate the effect of carbachol(CAR) on oxygen dynamic parameters and hyperlactacidemia during oral fluid resuscitation of burn shock.

METHODSTwelve male Beagle dogs were surgically prepared for cannulation of carotid and jugular vein, and enterostomy, 24 hours later they were subjected to a 50% (total body surface area, TBSA) full-thickness flame injury under a 10-15 minute anesthesia by IV injection of propofol. The dogs were randomized to gastric fluid infusion group (GI group)and gastric fluid infusion plus CAR group (GI + CAR). Either a glucose-electrolyte solution(GES) or GES containing CAR (20 microg/kg) were intragastricly given to animals in GI group or GI+ CAR groups. The delivery rate and volume of GES was in accordance with that of Parkland formula. Mean arterial pressure (MAP), intestinal mucosal blood flow (IMBF) and blood lactic acid were determined, and blood gas analysis evaluated for oxygen delivery (DO2), oxygen consumption (VO2) and oxygen uptake (O2ext) at 0, 2, 4, 8, 24, 48 and 72 hours after injury.

RESULTSThe levels of MAP and IMBF markedly reduced, and LAC obviously increased in both groups after burn. MAP returned to 0 h level at 72 h post burn, while IMBF, and LAC were still higher or lower than 0 h levels. The level of MAP of GI + CAR group was significantly higher than that of GI group at 2 h, and those showed no significant differences between two groups after then. Carbochol administration led to a markedly higher levels of IMBF, and significant lower levels of LAC from 8 h after burn compared with those of GI group (P < 0.05 or P < 0.01). The levels of DO2 VO2 and Oext were reduced markedly after burn in both groups. At 72 h after burn, DOQ returned to 0 h level; while VO2 and Oext though still much lower than 0 h levels. The level of DO2. VO2 and Oext of GI + CAR group were significantly higher than those of GI group from 8 h after burn (P < 0.05 or P < 0.01). Three of six animals died in GI+ CAR group, which was lower than two of six in GI group.

CONCLUSIONThe results indicates that carbachol promotes intragastric fluid resuscitative effect of burn shock by increasing oxygen delivery and decreasing hyperlactacidemia.