Impact of Mannitol on Left Atrial Pressure in Dogs With Mitral Regurgitation

BACKGROUND: Mannitol has been proven effective in treating cerebral oedema, owing to its osmotic diuretic effect. However, its potential to transiently increase plasma volume raises uncertainties about its impact on dogs with mitral avalve insufficiency. OBJECTIVES: This study aimed to investigate the effects of mannitol on haemodynamics and cardiac load in dogs with experimentally induced mitral regurgitation (MR), with a particular focus on the potential adverse effects of high doses of mannitol. METHODS: We used implantable telemetry to monitor MR dogs for 12 consecutive hours, recording and comparing the dynamic changes in their mean left atrial pressure (mLAP) and heart rate at different doses of mannitol (low [0.5 g/kg], medium [1 g/kg] and high [2 g/kg]). RESULTS: Compared with that in the control group, the low- and medium-dose groups demonstrated a proclivity towards increased mLAP after administration, but without statistical significance. The high-dose group exhibited an immediate increase in the mLAP after administration (p < 0.001), followed by a gradual return to baseline 1 h later. CONCLUSIONS: This study provides crucial reference data for the use of mannitol in treating MR. It is particularly important to exercise caution when administering high doses of mannitol to dogs with advanced stages of MR.