Evolution of hematocrit in burn patients as a marker of early fluid management during acute phase

Objective: To evaluate the value of hematocrit for monitoring fluid resuscitation of burn patients in the acute phase of their care.

Method: We conducted a single-center retrospective study focused on patients admitted with a burn surface of more than 20 % of the total body surface area (TBSA) from 2014 to 2021. We investigated the relationship between the change in hematocrit and the volume administered for patient resuscitation. The change in hematocrit is the difference between an admission hematocrit and a second one taken between the eighth and twenty-fourth hour.

Results: We included 230 patients with an average burn size of 39.1 ± 20.3 % TBSA, in 94.4 % by a thermal mechanism. The management seems to be in accordance with the current recommendations, with a volume administered during the first 24 h of 4.3 ± 2.5 ml/kg/ % BSA, allowing to obtain an hourly diuresis of 0.9 ± 0.7 ml/kg/h. We did not find any correlation between the pre-hospital volume administration and the hematocrit at admission (p = 0.36). Hematocrit decreased on average to -4.5 ± 8.1 % between admission and a control performed after the 8th hour. This decrease was weakly correlated with the volumes infused between the two samples (r² =0.13, p < 0.001). A resuscitation above 5.2 ml/kg/ % Burn surface area is an independent factor for excess mortality.

Conclusion: Hematocrit or its variations in our limited data base appears to not reliably detect over-resuscitation, therefore it is possible that it may not be a relevant marker. These conclusions should be clarified in a multi-institutional prospective or real-world analysis to validate the findings and null hypothesis.