The influence of haemorrhage and fluid resuscitation with either Plasma Lyte A or Ringer’s Lactate in Beagle dogs under sevoflurane anaesthesia Part 2: buccal mucosal microcirculation

To compare the effects of haemorrhage and subsequent fluid resuscitation with Plasma-Lyte A (PA) or Ringer’s Lactate (RL) on buccal microcirculation. Single centre, randomized, blinded, experimental study. Twelve adult healthy intact purpose-bred Beagle dogs. In sevoflurane anaesthetised Beagle dogs , a sidestream dark field (SDF) imaging device was positioned on the buccal mucosa to evaluate microcirculatory variables, which included perfused De Backer density (pDBD) and proportion of perfused vessels. Videos were recorded at baseline, following the removal of 30 mL kg -1 of blood to induce hypovolaemia (HV), and after each 10 mL kg -1 IV fluid bolus (B1 and B2) according to the assigned treatment group. Data were compared between groups and over time using a linear mixed model with group and timepoint as fixed and dogs as random factors. Post hoc multiple comparisons were performed with Sidak’s corrections. A p value < 0.05 was considered significant. The haemorrhage resuscitation model resulted in significant changes in microcirculation over time. In group RL, pDBD was significantly more reduced compared to group PA at HV [RL: 1.3 (0.9–1.8) mm -1 (median ± 95% confidence interval), PA: 2.3 (1.6–2.7) mm -1 , p = 0.004] and B2 [RL: 2 (1.7–2.7), PA: 3.3 (2.7– 4.2), p < 0.001]. Proportion of perfused vessels was also more reduced in group RL compared to group PA at HV [RL: 57 (53–77) %, PA: 78 (69–93) %, p < 0.001] and B2 [RL: 72 (65–96) %, PA: 85 (77–99) %, p = 0.012]. Dogs given PA showed fewer changes in pDBD and proportion of perfused vessels values after haemorrhage and resuscitation with 20 mL kg -1 PA compared to dogs given RL. Due to the small sample size these preliminary findings warrant further research.