RESUMEN
OBJECTIVE: To investigate the changes in myocardial dynamics in early phases of burn shock of dogs and the effects of rapid fluid infusion in delayed resuscitation. METHODS: Twelve mongrel dogs were randomly divided into control (n=6) and burn (n=6) groups. The dogs in burn group were subjected to 35% total body surface area (TBSA) III degree burn and were resuscitated with lactate Ringer's solution 6 hours postburn. The volumes and rates of fluid infusion were controlled basically on the urinary output of 1.0 mlxkg(-1)xh(-1) and cardiac output (CO) of 70%-80% of pre-burn values. The mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), maximum rate of intraventricular pressure rise/down (+/-dp/dt max) and cardiac index (CI) were determined at 0.5, 1,2, 6, 7, 8, 10 and 24 hours postburn. RESULTS: The MAP, LVSP, +/-dp/dt max and CI were significantly lowered from their baseline and those of control group at 0.5 hour postburn, and they kept declining until 6 hours postburn. They showed a tendency of elevation and reached or approached the levels of that in control group within 2 hours of resuscitation, and the differences were not significant between the two groups 4 hours after burn (all P>0.05). The amount of infusion fluid within the first 4 hours of resuscitation was (3.63+/-0.99) ml/kg per 1% TBSA. CONCLUSION: The myocardial dynamics is depressed in the early stage of burn, the effective way to improve it is to infuse a large amount of fluid rapidly when resuscitation is delayed.