The aim of the investigation was to improve the methods of sanitation of purulent foci. Efficacy of the purulent cavity lavage increased due to the changed direction of the flow of antiseptic solution. Experimental investigations showed that the down-flow lavage of purulent wounds with antiseptics was not enough. The drainage tube was irrigated and contact-exposure of the antiseptic with the wound discharge and microbes was not fulfilled completely. The changed flow of the liquid upwards, in vertical drainage the irrigation solution came outside the limits of the drain and irrigated the wound canal walls filling the whole wound cavity. Bacteriological investigations showed decreased bacterial dissemination of the purulent wounds due to the adequate filling of the wound cavity through the drain. The number of complications considerably decreased, the period of hospital treatment was 1.5 times shorter.