Transcapillary colloid osmotic pressures in injured and non-injured skin of seriously burned patients.

Thermal skin injury is accompanied by rapid and excessive oedema formation implicating a dramatic increase in the transcapillary fluid transport. In order to clarify the pressure changes occurring across the microvasculature after a thermal skin injury we have measured colloid osmotic pressures (COP) in interstitial fluid (COPi) of injured and non-injured skin as well as in plasma (COPp) from patients suffering major cutaneous burns. Interstitial fluid was collected with a wick-technique and analysed for COP. Measurements were performed as early as 6 h and continued until 56 h after injury. A severe hypoproteinaemia occurred in all patients with a marked reduction in COPp down to about 10 mmHg. Up to 12h post-burn we found a higher COPi in injured skin than in plasma. The first measurement of COPp averaged 9.8 mmHg as compared to an average COPi of 11.1 and 9.3 mmHg in injured and non-injured skin respectively. Measurements performed later than 12h showed a return of the transcapillary COP gradient towards the normal direction (COPp greater than COPi). The gradient was considerably less than in a normal situation. Based on the present observations of transcapillary COP it is suggested that colloids should be withheld until the transcapillary COP gradient returns to the normal direction.