Objective and design: Experimental studies in our laboratory showed that hypertonic saline dextran (HSD; 7.5 NaCl in 6% dextran 70) given as a small bolus (4 mL/kg) immediately after burn injury in guinea pigs improved cardiac contractile performance and reduced the total fluids requirements. Although these data confirm the cardioprotective effects of HSD given immediately postburn, prehospital and early inhospital management of severely burned patients consists of aggressive crystalloid fluid resuscitation to correct intravascular volume deficits. The question arose as to whether delaying HSD for several hours after initiating crystalloid resuscitation would provide cardioprotection.
Materials and methods: Third-degree scald burns comprising 45 +/- 1% of the total body surface area (burn groups, n = 40) or 0% for controls (group 1, n = 12) were produced; in groups 2 to 5, lactated Ringer's (LR) resuscitation was initiated immediately postburn according to the Parkland formula, 4 mL/kg/% burn. In group 2, (n = 12), LR was continued for 24 hours. HSD was administered as an i.v. bolus at either 1 hour (group 3, n = 10), 4 hours (group 4, n = 9), or 8 hours postburn (group 5, n = 9); immediately after HSD administration, LR was continued (1 mL/kg/% burn) until 24 hours postburn.
Results: Compared to sham burn controls, hearts from burned animals treated with LR alone had significant cardiac dysfunction, as indicated by a lower left ventricular pressure and +/- dP/dt. Compared with hearts from LR-treated animals, hearts from burned animals treated with HSD 1 hour (HSD-1) and 4 hours (HSD-4) after burn injury had significantly higher LVP and +/- dP/dt. Ventricular function curves calculated for HSD-1 and HSD-4 groups were comparable to those calculated for hearts from sham burns. Delaying HSD administration until 8 hours after burn provided little cardioprotection.
Conclusions: Our data indicate that HSD effectively maintains cardiac function and reduces overall total fluid requirements if administered within 4 hours after burn injury.