The Development Of A Neotype Cryoprobe Used In Bronchial Interventional Therapy

Epidemic situation of tuberculosis is severe and measures of tuberculosis control have to be enforced urgently. Endobronchial tuberculosis is paied more attention because of its high disease incidence and virulence. Systemic anti-tuberculosis chemotherapy and atomizing inhalation drug treatment of endobronchial tuberculosis have unsatisfactory therapeutic effects, therefore the interventional therapy is absolutely necessary. For the past few years, several kinds of bronchoscopic interventional techniques were utilized in clinic treatment of endobronchial tuberculosis, including local administration, laser therapy, high frequency electrotherapy, microwave therapy, argon plasma coagulation, cryotherapy, balloon dilation, stent placement. Cryotherapy has become a superiority skill because it has some good qualities: high security, short and long-term effect, inhibition of granulation hyperplasia, immunologic enhancement. There are distinct disadvantages in conventional cryoprobe because of its straight form. The conventional cryprobe can not touch the lesions located in special position such as bilateral apical segmental of upper lobes and posterior segment of lower lobes, so that interventional therapy can not be applied. The superior part and inferior part of lesions can not be treated at the same time with conventional cryprobe, so that treatment opportunity is missed and treatment efficiency is reduced. We have urgent need to develop a neotype cryprobe.In this research, a neotype cryprobe used in bronchial interventional therapy was developed that was designed to has self-bending fuction. The region is augmentated with combination of neotype cryprobe's self-bending and bronchoscope operation. The treatment efficiency is increased by cryotherapy of the superior part and inferior part of lesions simultaneously with neotype cryoprobe.Firstly, options screening and materials optimization of neotype cryoprobe were completed. We designed several solutions such as machine dragging, memory alloy, gas pressure. Among these solutions, memory alloy method was selected as a final project. Mechanical properties and service life of new materials were observed. We selected the diameter of 0.6mm, 0.1mm wall thickness of the Ni-Ti shape memory alloy capillary probe as material for a neotype cryoprobe.Secondly, trial production and testing were completed. We took special measures for high-strength Ni-Ti shape memory alloy capillary processing, abandoned the conventional probe dug in cutting pipe welding method for refrigeration, adopted creatively the orifice means for refrigeration. We conducted a new production process of neotype cryoprobe testing to ensure product quality, and conducted the test parameters of some products, cryoprobe to the medical quality management requirements. Thirdly, serialization and simulation touching experiment of neotype cryoprobe were completed. According to assembly of angle and length of Ni-Ti shape memory alloy capillary, we manufactured specifications of the Ni-Ti shape memory alloy capillary to serialized neotype cryoprobes. Simulation touching experiment was carried out with bronchoscope operating model, in vitro and in vivo canine bronchial - lung specimens. We found that the difficulty of the operation was greatly reduced and touch regions were augmentated with the series of neotype cryoprobe compared to with the conventional cryoprobe.Fourthly, the performance of neotype cryoprobe was evaluated preliminary. After endobronchial cryotherapy of experimental rabbits and dogs, vital signs and local tissue reactions were observed, general situation, blood routine and arterial blood gas analysis were monitored, local tissue pathology and ultramicrostructure changes were observed. We found that endobronchial cryotherapy had no effect to vital signs of experimental animals, the red blood cells, white blood cells of systemic blood circulation of and arterial blood gas. The tissue injury of endobronchial cryotherapy has selectivity. Endobronchial cryotherapy can damage the tracheal mucosa and submucosa, connective tissue and cartilage had no significant damage. Cryotherapy is a kind of treatment of non-immediate effect. Cell damage can only be observed from the microstructure instantly, morphological changes can not be found in general and with light microscope. Freezing effects often reached a peak at about 72h, the damaged structure recoveried by tissue repair. In this aspect, the effects caused by neotype cryoprobe and conventional cryoprobe have no significant difference.Fifthly, Changes in immune status of experimental dogs were observed after endobronchial cryotherapy. T cell subsets and IL-1β,IL-6,IL-8,IL-10,TNF-αin peripheral blood were detected after endobronchial cryotherapy. We found that the levels of some cytokines in peripheral blood changed but T cell subsets in peripheral blood had no change. In this aspect, the effects caused by neotype cryoprobe and conventional cryoprobe have no significant difference.Conclusions: 1. Memory alloy method can be a solution for a neotype cryoprobe, Ni-Ti shape memory alloy capillary can be used as a good material to produce a neotype cryoprobe. 2. Based on memory alloy method and Ni-Ti shape memory alloy capillary, neotype cryoprobes can be produced successfully and have good cooling and security. 3. Series of neotype cryoprobes could meet a variety of different length and angle of bronchus. The touch regions were augmentated with the series of neotype cryoprobe compared to with the conventional cryoprobe. 4. The effects caused by neotype cryoprobe and conventional cryoprobe have no significant difference. Endobronchial cryotherapy has a high security and is a kind of treatment of non-immediate effect. 5. Endobronchial cryotherapy could stimulate the body's immune response and gain immune effects. In this aspect, the effects caused by neotype cryoprobe and conventional cryoprobe have no significant difference.