Development of a Gastight Thoracotomy Model for Investigation of Carbon Dioxide Field-Flooding Efficacy

Abstract

Carbon dioxide (CO 2 ) field-flooding during cardiac surgery is a prevention technique to avoid blood-air contact and subsequent embolization. Although it was first used more than 60 years ago, there is still some perplexity around its efficacy, mainly because the gas is invisible and air embolization is difficult to quantify.An accurate assessment of field-flooding can, therefore, best be performed in models where various methods can be tried in a controlled environment and evaluated with industrial-grade sensors. Multiple options are available for anatomically correct models that reproduce a sternotomy situation, but models for minimally invasive cardiac surgery are expensive and normally meant for training of surgical techniques where only the top side of the model is important.We created a low-cost and "home-made" gastight mini-thoracotomy model with internal organs and left atrial incision to investigate CO 2 insufflation in a simulated minimally invasive mitral valve surgery. The model was validated with CO 2 field-flooding tests with a commercial diffuser, while three sensors continuously registered the local concentration of CO 2 gas.

Patient Tilt Improves Efficacy of CO2 Field-flooding in Minimally Invasive Cardiac Surgery

“…As known from sternotomy model studies, the higher the ow rate, the faster the surgery eld gets ooded and the higher the concentration in the thorax can get 9,11 . This is clearly a dynamic process where the gas delivery needs to continue because otherwise diffusion and convection rapidly increase the air content inside the thorax 9,10,12 . The same statements are valid for this MICS model, where a ow rate of only 1 l/min has some speci c concerns that fade at higher ows.…”

“…The patient thorax is simulated by a hollow mannequin torso lled with a set of orthotopically organized models of various organs (heart, aorta, lungs, trachea, diaphragm, ribs, spine) embedded in a gastight mediastinum 10 . To simulate minimally invasive cardiac surgery, a hole (~skin incision) was cut in the torso around the 5th intercostal space and the ribs were spread such that a soft retractor could be inserted (see Figure 1).…”

“…In this laboratory model study we tried to achieve a better understanding on how CO 2 gas behaves during MICS surgery, while it is delivered in the patient cavity, comparing different ow rates, commercial gas delivery tools and patient's orientation (simulating a tilted OR table). This was achieved by a realistic gastight torso model foreseen with an intraventricular CO 2 concentration sensor 10 and by a simpli ed transparent thorax model where gas clouds could be visualized via the Schlieren imaging technique 9 .…”

Patient tilt improves efficacy of CO2 field-flooding in minimally invasive cardiac surgery

“…The patient thorax is simulated by a hollow mannequin torso filled with a set of orthotopically organized models of various organs (heart, aorta, lungs, trachea, diaphragm, ribs, spine) embedded in a gastight mediastinum [ 10 ] with approximately 7 L of volume, including the organs. To simulate minimally invasive cardiac surgery, a hole (~ skin incision) was cut in the torso around the 5th intercostal space and the ribs were spread such that a soft retractor could be inserted (see Fig.…”

“…In this laboratory model study we tried to achieve a better understanding on how CO 2 gas behaves during MICS surgery, while it is delivered in the patient cavity, comparing different flow rates, commercial gas delivery tools and patient’s orientation (simulating a tilted OR table). This was achieved by a realistic gastight torso model foreseen with an intraventricular CO 2 concentration sensor [ 10 ] and by a simplified transparent thorax model where gas clouds could be visualized via the Schlieren imaging technique [ 9 ].…”