The relationships between routine admission blood tests and burn size, and length of stay in intensive care unit

Abstract

Although blood test is a routine in major burns, its relationship with burn size and intensive care unit length of stay (ICULOS) remains undetermined. We investigated the feasibility of using these tests as a reference for definite diagnosis of major burn size, burn size >20% of the total body surface area (TBSA), and their relationships with ICULOS. Data of routine laboratory blood tests within 24h after burns (n=73) were collected retrospectively. Correlation tests and regression analyses were performed. Burns ≥20TBSA had higher incidences of leucocytosis, hypoalbuminaemia, elevated haemoglobin (Hb), and elevated haematocrit (Hct). Burn size was correlated negatively with albumin but positively with Hb, Hct, and white blood cell (WBC) count. For each unit increase in blood urea nitrogen (BUN)/creatinine (Cr), there was an increase of 1.2 days of ICULOS in females, while in males, there was a 6.7 day increase for every unit increase in Hb and a 3.1 day increase for each unit increase in BUN. A female model including Hb and WBC was derived, discriminating burns ≥20TBSA with sensitivity and specificity 0.94 and 1.0 respectively, and area under the receiver operating characteristic curve (AUROC) 0.96 (95% CI 0.91-1.00). The male model had sensitivity 0.96, specificity 1.0, and AUROC 0.96 (95% CI 0.89-1.00). Admission Hb and WBC could be used as a reference for definite diagnosis of major burn size, especially in borderline cases. BUN/Cr in females, and Hb and BUN in males, were related to ICULOS.