Introduction:
The functional purpose of a bioresorbable pleural implant is to provide a reversible collapsosurgical effect on the area of lung tissue in which the tuberculous cavity of destruction (cavity, fibrous cavity) is located, by preserving the volume and shape of the implant for a given time, followed by bioresorption and restoration of the volume and function of the affected lung.

Objective:
To evaluate changes in the volume and shape of highly porous implants based on polylactide (PLA) and polycaprolactone (PCL) during intrapleural implantation in an experiment.

Material and Methods:
The objects of research are porous disks with a diameter of 20 mm and a height of 10 mm of two compositions. Sample No. 1 consists of a mixture of PLA/PCL with a polymer ratio of 3:1 (3 wt.%). Sample No. 2 is made of PLA/PCL with a polymer ratio of 1:1 (1.7 wt.%). Laboratory samples of pleural implants were obtained by cryoliophilization. The porosity ranges from 97.0 to 98.3%, and the Young's modulus is from 100 to 1800 kPa.
Implantation was performed in 5 rabbits simultaneously in both pleural cavities under endotracheal anesthesia. The duration of implantation was 7-21-54-76-78 weeks. The consistency, dynamics of changes in the volume and shape of the implants were evaluated.

Results:
There is a stable preservation of the volume and shape of both samples for 21 weeks. After 54 weeks, the volume of samples No. 1 and No. 2 decreases only by 10 and 20%, which is not a clinically significant decrease in volume. A significant decrease in volumes is observed in the fourth and fifth periods of implantation, for samples No. 1 and No. 2 – 90% and 96%, respectively. The loss of volume occurs mainly due to a decrease in the thickness of the implant. At all implantation periods, the soft-elastic consistency of both samples is preserved.

Conclusions:
The clinically significant preservation of the volume and shape of the samples until the third implantation period (54 weeks) indicates the prospects of both studied laboratory samples in clinical use. Considering that the terms of bioresorption of pleural implants in living organisms correlate with the level of metabolism, it can be assumed that in clinical conditions the studied highly porous pleural implants will provide a collapsosurgical effect in the target time from 1 to 3 years or more.