Value of sublingual microcirculation on hemorrhage severity in the pig

Objective To investigate the value of sublingual microcirculation on hemorrhage severity in the pig. Methods Twenty healthy male pigs were randomized into four groups according to the percentage of blood loss volume (the total blood volume was assessed for 70 ml/kg): sham group, 25% blood loss group, 35% blood loss group and 45% blood loss group, 5 pigs in each group. The levels of mean arterial pressure, cardiac output, blood lactic acid, microvascular flow index (MFI) and perfused vessel density (PVD) were regularly evaluated on 30 min, 1 h, 2 h, 3 h, and 4 h after hemorrhage. The body mass, heart rate, mean arterial pressure, cardiac output, blood lactic acid, MFI and PVD before hemorrhage were compared. Results The body mass, heart rate, mean arterial pressure, cardiac output, blood lactic acid, MFI and PVD before hemorrhage all showed no significant differences among four groups (F = 0.156, 0.260, 0.467, 0.417, 0.434, 1.778, 0.149; all P> 0.05). When the volume of blood loss was gradually increased, the mean arterial pressure and cardiac output on 30 min [(117 ± 8), (56 ± 10), (45 ± 4), (31 ± 5) mmHg, (4.80 ± 0.54), (3.32 ± 0.32), (2.35 ± 0.37), (1.67 ± 0.15) L/min], 1 h [(123 ± 4), (89 ± 6), (67 ± 8), (52 ± 8) mmHg, (4.79 ± 0.63), (3.99 ± 0.37), (2.75 ± 0.35), (2.05 ± 0.39) L/min] after hemorrhage decreased (all P< 0.05), blood lactic acid on 1 h after hemorrhage increased [(1.12 ± 0.33), (2.10 ± 0.25), (3.74 ± 1.38), (5.88 ± 1.48) mmol/L; all P< 0.05], and MFI [(2.92 ± 0.09), (2.47 ± 0.28), (1.30 ± 0.14), (0.87 ± 0.27); all P< 0.05] and PVD [(4.95 ± 0.12), (4.20 ± 0.54), (2.98 ± 0.10), (2.64 ± 0.31); all P< 0.05] on 30 min after hemorrhage declined. Pearson correlationanalysis showed that MFI and PVD were positively associated with mean arterial pressure (r = 0.903, 0.923; all P< 0.05) and cardiac output (r = 0.919, 0.919; all P< 0.05), and negatively correlated with blood lactic acid (r = -0.706, -0.745; all P< 0.05). Conclusion Sublingual microcirculation can indicate the changes of blood loss in real time, and effectively predict the severity of hemorrhage. Key words: Microcirculation; Hemorrhage; Microvascular flow index; Perfused vessel density