Heparin protects local skin microcirculation in 210 minutes-long intravital microscopy observations under general anaesthesia

Prolonged immobilization of severely-ill, bed-ridden patients results in fo rmation of pressure ulcers following inappropriate tissue blood perfusion, and local activation of leukocyte-endothelial cell interactions (L/EC). Var ious treatment modalities were implemented to improve local microcirculatio n with controversial results. The aim of our study was to investigate the i nfluence of heparin and buflomedil, drugs improving the microcirculation, o n local skin blood perfusion using intravital fluorescent microscopy (IVM) technique. Material and Methods: Experiments were carried out on 24 male hairless mice under inhalatory isofluran anaesthesia. Intravenous injection of FITC-dext ran (150 kD, 5%) allowed to visualize capillaries during IVM, after immobil isation of hind limb, in an observation chamber. Observations were performe d after i.v. injection of heparin (66 IU/kg b.w., n = 8) or buflomedil (6 m g/kg b.w., n = 8) 30, 120 and 210 minutes after chamber installation. Obser vations were recorded in 30 sec sequences on S-VHS tapes and evaluated usin g special software. Functional capillary density (FCD), defined as a total length of red cells perfused capillaries per observation field (expressed i n cm/cm(2)), postcapillary venule diameters, and number of sticking leukocy tes per 0.2 mm vessel length during 30 sec observation time, served as para meters of skin blood perfusion and activation of L/EC interactions. Results: A statistically significant decrease of FCD from 152.7 +/- 38.5 to 100.7 +/- 36.7 cm/cm(2) (p<0.05) was observed in control animals during 21 0 min lasting observation. Administration of heparin prevented decrease in FCD occurring in control animals during intravital microscopy, whereas bufl omedil was found ineffective. Both drugs induced a nonsignificant reduction in the number of sticking leukocytes, whereas no changes in postcapillary venule diameters could be observed. Conclusion: The results suggest a protective effect of heparin in clinical therapeutic doses against impairment of skin perfusion during IVM. This obs ervation may justify a trial on the effects of heparin in prevention of dev elopment of pressure ulcers.