The effects of vasopressors with and without dobutamine on haemodynamics, metabolism and gut injury during endotoxic shock in rabbits. A controlled study.

INTRODUCTION: Vasopressors increase arterial pressure but they may have deleterious effects on mesenteric blood flow. We aimed to evaluate the response of gut biomarkers and superior mesenteric blood flow to different vasopressors with and without dobutamine. MATERIAL AND METHODS: Thirty New Zealand rabbits were included and randomly allocated to 5 groups: group A - sham group; group B - norepinephrine; group C - norepinephrine plus dobutamine; group D - vasopressin; and group E - vasopressin plus dobutamine. Mean arterial pressure (MAP) target was greater than 60 mmHg. Endotoxic shock was induced by intra-venous injection of lipopolysaccharide (LPS) in four of the five groups. Aortic blood flow (Qao), superior mesenteric artery flow (QSMA) and lactate were measured after LPS injection. Enterocyte damage was evaluated by measurements of serum citrulline and intestinal fatty acid-binding protein (I-FABP) after 4 h. RESULTS: The largest reduction in Qao occurred in group D (64 ± 17.3 to 38 ± 7.5 mL min-1; P = 0.04). QSMA also declined significantly in groups D and E and remained lower than in the other groups over 4 h (group D - baseline: 65 ± 31; 1 h: 37 ± 10; 2 h: 38 ± 10; 3 h: 46 ± 26; and 4 h: 48 ± 15 mL min-1; P < 0.005; group E - baseline: 73 ± 14; 1 h: 28 ± 4.0; 2 h: 37 ± 6.4; 3 h: 40 ± 11; and 4 h: 48 ± 11; P < 0.005; all in mL min-1). Serum citrulline was significantly lower in groups D (P = 0.014) and E (P = 0.019) in comparison to group A. The fluid administration regimen was similar in all groups. CONCLUSIONS: Vasopressin seems to negatively impact gut enterocyte function during endotoxic shock despite the association of an inodilator and adequate fluid replacement.

Efeito da solução de Ringer com lactato sobre os equilíbrios hidroeletrolítico e acidobase de equinos, ovelhas e bezerros sadios / Effect of lactated Ringer’s solution on fluid, electrolyte and acid-base balances of healthy horses, ewes and calves

O objetivo deste trabalho foi investigar os efeitos da solução de Ringer com lactato (SRL) sobre os equilíbrios hidroeletrolítico e acidobase de equinos, ovelhas e bezerros hígidos. Equinos adultos (n=6), ovelhas adultas (n=6) e bezerros (n=5) receberam a SRL em volume correspondente a 10% do peso corporal, administrada por infusão contínua intravenosa durante quatro (ovelhas e bezerros) ou seis (equinos) horas. Amostras de sangue venoso e de urina foram colhidas antes do início da infusão, na metade do volume infundido, ao término da infusão e duas (ovelhas e bezerros) ou três (equinos) horas após. Foram determinados valores de pH sanguíneo e urinário, de pCO2, HCO3- e BE no sangue, de Na+, K+, Cl- e SID no soro, de AG, PPT, Atot e lactato L no plasma e das excreções fracionadas urinárias de Na+, K+, Cl- e lactato L. A SRL provocou hemodiluição e não afetou os equilíbrios eletrolítico e acidobase nas três espécies estudadas, não sendo capaz de promover aumento da reserva alcalina. Por outro lado, deve ser considerada segura para a terapia de manutenção com infusão de grandes volumes porque não provoca desequilíbrios eletrolíticos.

The effects of lactated Ringer's solution (LRS) on fluid, electrolyte and acid-base balances were investigated in healthy horses, ewes and calves. LRS was intravenously infused in six adult horses, six adult ewes and five calves in a volume corresponding to 10% of body weight, continously during four (ewes and calves) or six (horses) hours. Venous blood and urine samples were taken before the beginning, in the middle, at the end of the infusion and two (ewes and calves) or three (horses) hours after. Blood and urine pH, blood pCO2, HCO3- and BE, serum Na+, K+ and Cl-, and plasma TP and L lactate were measured. Na+, K+, Cl- and L lactate fractional clearance and plasma SID, AG, and Atot were calculated. In all species LRS caused hemodilution but didn't change electrolyte and acid-base balances. It was not able to increase alkali reserve. On the other hand, LRS must be considered safe for maintenance therapy with large volume infusions because it doesn't induce electrolyte imbalances.