Effects of Chest Tube Position on Drainage and Pressure

Chest tube (CT) drainage has become a common practice in a variety of units not only in military but in civilian hospitals as well. The standard length of drainage tubing makes it difficult to prevent the formation of dependent loops even under the best conditions in a hospital. It is more difficult to prevent the formation under the austere conditions of wartime, contingencies, and aeromedical evacuation. The results of this study have the potential of maximizing chest drainage systems, thus reducing treatment time, patient discomfort, and health care costs. The purpose of this study was to examine the effects of differences in positioning of chest drainage tubes on pressure and volume of drainage for one hour. The following research questions were addressed: (1) Are there differences in the amount of drained fluid that accumulate in one hour between tubes that are straight, coiled, or in dependent loops (with and without periodic lifting and draining)? (2) Are there differences in pressure at the connection between the chest tube and the drainage tube between tubes in the four positions? (3) Are there differences in pressure where the drainage tube enters the drainage collection device between tubes in the four positions? (4) Are there differences in the pressure difference between the beginning of the drainage tube and the end when the tubes are in the four positions? CTs and a large bore intravenous catheter were inserted into eight pigs, and the chest tube was connected to a standard drainage system with a suction level of -20 cm H₂O. 500 mL of normal sterile saline were injected into the pleural space through the intravenous catheter over a 45- minute period. The volume of fluid drained and the pressure within the drainage system were measured at intervals over one hour for the following positions: tubing straight, tubing coiled, tubing allowed to hang in an dependent loop and tubing in a dependent loop but with tubing lifted. A repeated measures analysis of variance (ANOVA) was used to examine the relationship between the volume of fluid drained and the drainage tube position. After 60 minutes, significantly less fluid (least significant difference test, p=0.03) was drained with the dependent-loop tubing position than with the other three positions. The amount of fluid drained was not significantly different among the lift and drain (250 mL), coiled (301 mL) or straight (337 mL) tubing positions. Throughout the entire study, pressure at the connection between the chest tube and drainage tube was significantly higher (least significant difference test, p =0.03) for the dependent loop with and without periodic lifting and draining. The conclusion is that straight and coiled tube positions are optimal for draining fluid from the pleural space. If a dependent loop cannot be avoided, lifting and draining it every 15 minutes will maintain adequate drainage.