The influence of haemorrhage and fluid resuscitation with either Plasma-Lyte A or Ringer’s Lactate in Beagle dogs under sevoflurane anaesthesia—part 1: Macrocirculation

OBJECTIVE: To compare macrocirculatory effects of haemorrhage followed by fluid resuscitation with Plasma-Lyte A (PA) or Ringer's Lactate (RL) crystalloid solution in dogs under sevoflurane anaesthesia. STUDY DESIGN: Single-centre, randomised, blinded, experimental study. ANIMALS: A group of 12 adult, healthy, intact, purpose-bred Beagle dogs. METHODS: PA or RL administered intravenously over 10 minutes. Data were compared using a linear mixed model with group and time points as fixed factors and dogs as a random factor, and corrections for multiple comparisons. A p value < 0.05 was considered significant. RESULTS: , p < 0.001]. The increase of MAP in RL was significant at B1 [15 (1-29) mmHg, p < 0.028] and B2 [16 (2-30) mmHg, p < 0.016] compared with HV, while MAP in PA was not significantly different at B1 [3 (-11 to 17) mmHg, p = 0.995] and B2 [4 (-9 to 18) mmHg, p = 0.943] compared with HV. CONCLUSIONS AND CLINICAL RELEVANCE: In this small experimental study, both fluids tested led to a clinically significant increase in CO. No consistent increase in MAP was observed across fluid types. Alterations in MAP should not be used as a surrogate for flow variables to assess fluid responsiveness.