Systemic TNF concentration and haemodynamic parameters. Peak TNF plasma levels during/or after ILP and haemodynamic parameters in 38 patients who underwent TIM- or TM-ILP. Bioactive peak TNF concentrations ranged from 0.03 ng/ml to 1,728 ng/ml (right ordinate). Indexed resistance of vascular system (IRVS) and maximal arterial pressure (MAP) are expressed as a percentage of the baseline value. They represent the worst value measured at any time during or after ILP. In spite of the very large range of systemic TNF concentrations, there was no correlation with haemodynamic parameters. There was evidence for extremely variable individual sensitivity to TNF.