Serotonin kinetics in patients with burn injuries: A comparison between the local and systemic responses measured by microdialysis—A pilot study

ObjectivesTo investigate serotonin (5HT) locally in burned and uninjured skin (intracutaneous) by microdialysis, and simultaneously record urinary and blood values in the same subjects. For comparison, serotonin values were also measured in skin of healthy controls.Design and settingAn experimental study in burned patients with of more than 25% TBSA (total burn surface area) % in an 8-bed tertiary burns unit, serving about 3.5 million persons.Patients and methodsSix subjects with a median TBSA% of 59% (range 33.5–90), and five healthy controls were examined by intracutaneous microdialysis of the skin.Results5HT was increased in burned patients, compared with controls. This increase was tenfold in skin and was noted both in uninjured and burned skin. The highest values were recorded on day 1 (median 16.1 nmol in uninjured and 9.5 nmol in burned skin) and day 2 (15.6 nmol in uninjured and 13.4 nmol in burned skin). A rapid reduction was noted on day 3 (4.9 nmol in uninjured and 3.8 nmol in burned skin). The corresponding value for control subjects was 1.3 nmol. The 5HT in blood was twice normal on day 2, and gradually reduced on days 3 and 4 (3189, 3035 and 2573 nmol, respectively). Urinary 5HT concentrations were increased only on day 2 at 1755 nmol and thereafter returned to the normal range on days 3 and 4 (1248 and 1344 nmol, respectively).ConclusionsWe showed that microdialysis may be used in the critical care of burns, and local skin serotonin concentrations examined continuously for several days. The findings of significantly raised tissue serotonin concentrations, compared to that in blood and urine, suggests that serotonin may be important in local vascular control and formation of oedema.