Ex-vivo human lung tumor model: use for temperature measurements during thermal ablation of NSCLC

BipoJet Scissors as an Alternative to Laser in Lung Wedge Resection

INTRODUCTION

An important goal in every lung resection is airtight closure of the resected lung surface. This can be achieved with several techniques, including clamp resection, stapler, laser, and various high-frequency methods. By quantitatively measuring the air fistula across the resection surface of porcine lungs, two resection techniques were compared in our study: BipoJet dissecting scissors (Aesculap, Inc., Tuttlingen, Germany) and laser (Ceralas HPD®, Biolitec Inc., Jena, Germany).

METHODS

Following a stencil, wedge resections were performed in porcine lungs using water-irrigated bipolar scissors and laser (1350 nm, 40 watts, non-contact mode). The volume of the air fistula was then measured. The irrigation technique involved the attachment of an irrigation channel to a pair of standard surgical scissors. A sodium chloride (NaCl) solution was fed at a defined flow rate, along the blades of the scissors onto the parenchyma. This technique was used on a total of 10 specimens each.

RESULTS

Somewhat better pneumostasis was achieved with laser resection, though the difference was small and not statistically significant. The flow rate was 124 mL/min/cm² after laser resection and 145 mL/min/cm² after using the BipoJet scissors. The difference was not statistically significant. Water irrigation during resection with the BipoJet scissors prevents the temperature in the tissue from exceeding 100°C thus avoiding tissue carbonization. These scissors offer the following advantages: ease of use, no need to change instruments, no need for staff training, no protective measures, all-in-one incision/coagulation/dissection, low cost, and a clear surgical field due to the irrigation effect.

CONCLUSIONS

Resection of lung parenchyma, e.g., during resection of metastases, is easier with BipoJet scissors and comparable to laser resection. This was established both experimentally and by resecting lung metastases.

The Effect of Cooling Fluid Composition on Ablation Size in Hepatic Laser Ablation: A Comparative Study in an Ex Vivo Bovine Setting

PURPOSE

Hyperthermic ablation is a minimally invasive mode of tumour therapy which serves as a viable alternative to surgical intervention. However, one of the major drawbacks, besides the heat sink effect and the risk of damaging adjacent organs, is limited ablation size. The use of a cooling fluid during ablation has been shown to increase the ablation volume and decrease the carbonisation rate. The aim of this study was to investigate whether the composition of the cooling fluid has an effect on ablation size and carbonisation rate during hepatic laser ablation in an ex vivo bovine setting.

METHOD

In this study bovine hepatic tissue was ablated in an ex vivo setting using an internally cooled laser applicator. A total of 45 tissue samples were assigned to three groups: 0.9% saline infusion (n = 15), distilled water infusion (n = 15) and a 50%/50% mixture of 0.9% saline and distilled water (n = 15). Ablation was conducted using a 1064 nm Nd:YAG laser at a wattage of 25 W and time interval of 10 min. The ablation volume and carbonisation rate were then measured and recorded through postprocedural MRI. One-way ANOVA and post-hoc testing were performed to assess the effect of the cooling fluid composition on the ablation volumes.

RESULTS

We found that using a mixture of saline and distilled water as a cooling fluid during hyperthermic ablation resulted in a larger ablation volume (mean ± SD: 22.64 ± 0.99 cm3) when compared to saline infusion (21.08 ± 1.11 cm3) or distilled water infusion (20.92 ± 0.92 cm3). This difference was highly significant (p < 0.001). There was no significant difference in ablation size between the saline group and the distilled water group. The highest carbonisation rate occurred in the saline group (12/15), followed by the mixed infusion group (3/15) and the distilled water group (1/15).

CONCLUSIONS

The results of this study suggest that cooling fluid composition during hepatic laser ablation affects ablation volume in an ex vivo bovine setting. There was no statistically significant difference when comparing ablation volumes during saline infusion and distilled water infusion, but the carbonisation rate was significantly higher when using saline. The combination of saline and distilled water in a 50%/50% mixture as cooling fluid appears to be an auspicious alternative, as ablation volumes created with it are larger when compared to saline and distilled water alone, while carbonisation rate remains low. This might improve patient outcome as well as patient eligibility for hyperthermic ablation.

Implementation of an experimental isolated lung perfusion model on surgically resected human lobes

Isolated lung perfusion (ILP) is an ideal model to study treatment effects on a variety of pathologies. As published research mostly relies on rejected donor lungs or animal organs, this study investigates the use of surgically resected human lobes as an alternative and novel model for personalized experimental research. Ten surgically resected lobes were perfused in acellular and normothermic condition. The indication for surgery was lung cancer. Perfusion and ventilation were adapted to the size of the lobes and both functional and metabolic parameters were assessed during ILP. Patients (age 67.5 y (59–81)|♀n = 3|♂n = 7) underwent anatomic pulmonary lobectomy. Ischemic time between arterial ligation and ILP was 226 minutes (161–525). Median duration of ILP was 135 (87–366) minutes. Gas exchange and mechanical respiratory parameters remained steady during ILP (pulmonary venous pO₂ 196(151–219) mmHg | peak AWP: 14.5(11–22) cmH₂O). Metabolism stayed constant during ILP (Glucose consumption: 1.86 mg/min/L_TLC (95%CI: −2.09 to −1.63) | lactate production: 0.005 mmol/min/ L_TLC (95%CI: 0.004 to 0.007)). ILP of surgically resected human lobes is a feasible and promising method. By maintaining a near physiological setting, this model may pave the way for future experimental lung research including cancer research, transplantation, physiology, pharmacology and mechanical ventilation.