Experimental study in protecting lung with controlled lung collapse

Abstract

Objective To investigate the protective effect of controlled lung collapse using a new type single-cavity lung isolation catheter ventilation tool in dogs undergoing thoracotomy. Methods Eighteen dogs were randomly divided into three groups (n=6). After induction of general anesthesia, all dogs were intubated with the controlled intrapulmonary balanced gas lung isolation catheter, and then two Swan-Ganz floating catheters were inserted into the femoral artery and the right internal jugular vein respectively for blood pressure monitoring and blood sample collection. After 20 min of two-lung ventilation (TLV), one-lung ventilation (OLV) was performed to collapse the right lung. The degree of collapse in the right lung in group A, B and C was respectively maintained at 100%, 90% and 50% by a microcapsule. Blood samples from the femoral artery and jugular vein were collected at the following time points: 1 min before OLV (T1), 30 min (T2), 60 min (T3) and 120 min (T4) after OLV. The intrapulmonary shunt rate (Qs/Qt) was determined by blood gas analysis, and serum levels of intercellular adhesion molecule 1 (ICAM-1), malondialdehyde (MDA) and superoxide (SOD) were analyzed by ELISA. HR, femoral arterial blood pressure (ABP), mean pulmonary arterial pressure (MPAP), PEtCO2, rectal temperature and other vital signs were continuously monitored during the whole procedure. Results All physiological indices did not differ in all groups during TLV (P>0.05). OLV significantly elevated Qs/Qt, reduced production of serum ICAM-1 and MDA, and increased serum SOD production in a time dependent manner among all groups. The dogs with 90% and 50% lung collapse showed reduced MPAP, lower serum ICAM-1 and MDA, higher SOD production and lower Qs/Qt as compared to dogs with complete one lung collapse. Furthermore, when compared with 90% lung collapse, 50% lung collapse induced better lung protection as indicated by lower production of serum ICAM-1 and MDA and higher serum SOD production. Conclusions Controlled one lung collapse has beneficial effect on acute lung injury by minimizing inflammatory responses and attenuating impairment of lung function. Especially, 50% one lung collapse has better lung protective effect than 90% collapse. Key words: One-lung ventilation; Controlled lung collapse; Lung protection; Dogs