Airtightness of lung parenchyma without a closing suture after atypical resection using the Nd:YAG Laser LIMAX 120

Lung Metastatectomy: Can Laser-Assisted Surgery Make a Difference?

BACKGROUND

Resection of lung metastases with curative intention in selected patients is associated with prolonged survival. Laser-assisted resection of lung metastases results in complete resection of a high number of lung metastases, while preserving lung parenchyma. However, data concerning laser lung resections are scarce and contradictory. The aim of this study was to conduct a systematic review to evaluate the utility of laser-assisted pulmonary metastasectomy.

METHODS

An electronic search in MEDLINE (via PubMed), complemented by manual searches in article references, was conducted to identify eligible studies.

RESULTS

Fourteen studies with a total of 1196 patients were included in this metanalysis. Laser-assisted surgery (LAS) for lung metastases is a safe procedure with a postoperative morbidity up to 24.2% and almost zero mortality. LAS resulted in the resection of a high number of lung metastases with reduction of the lung parenchyma loss in comparison with conventional resection methods. Survival was similar between LAS and conventional resections.

CONCLUSION

LAS allows radical lung-parenchyma saving resection of a high number of lung metastases with similar survival to conventional methods.

Initial Airtightness of the Lung Parenchyma After Transection of the Interlobar Fissure - Monopolar Cutter, Stapler Versus Nd: YAG Laser

INTRODUCTION

Every lobectomy requires the transection of the interlobar fissure. Resection surfaces must be airtight in order to avoid leakage and infection. Using an ex vivo model based on porcine lung, we compared three techniques with respect to initial airtightness at different inspiratory pressures.

MATERIALS AND METHODS

In the first technique (group 1), we transected the interlobar fissure with a monopolar cutter and overstitched the edges of the resection area with a monofilament thread. In the second technique (group 2), the interlobar fissure was cut with a stapling device. In the third technique (group 3), the interlobar fissure was cut using a laser fibre connected to an Nd: YAG laser. The resection areas were not overstitched; 15 transections were performed in each group.

RESULTS

In group 1, three parenchymatous bridges leaked starting at a pressure of 25 mbar. In the other two groups, all preparations were airtight at this pressure. If the ventilation pressure was increased up to 40 mbar, all seams in group 1 were leaky at a pressure of 35 mbar. Four staple seams were airtight at a pressure of 40 mbar. In group 3, 11 preparations (73.3 %) were airtight up to a pressure of 40 mbar.

CONCLUSIONS

Based on our results, the use of an Nd: YAG laser is suitable for the transection of the interlobar fissure. In effect, this technique compares well with the other techniques examined.

Local Effects of a 1940 nm Thulium-Doped Fiber Laser and a 1470 nm Diode Laser on the Pulmonary Parenchyma: An Experimental Study in a Pig Model

The lungs are a common site of metastases from malignant tumors. Their removal with a minimal but safe tissue margin is essential for the long-term survival of patients. The aim of this study was to evaluate the usefulness of a 1940 nm thulium-doped fiber laser (TDFL) and a 1470 nm diode laser (DL) in a pig model of lung surgery that involved the incision and excision of lung tissue. Histopathological analysis was performed on days 0 and 7 after surgery. Neither TDFL nor DL caused significant perioperative or postoperative bleeding. Histological analysis revealed the presence of carbonized necrotic tissue, mixed fibrin-cellular exudate in the superficial zone of thermal damage and bands of deeper thermal changes. The mean total width of thermal damage on day 0 was 499.46 ± 61.44 and 937.39 ± 109.65 µm for TDFL and DL, respectively. On day 7, cell activation and repair processes were visible. The total width of thermal damage was 2615.74 ± 487.17 µm for TDFL vs. 6500.34 ±1118.02 µm for DL. The superficial zone of thermal damage was narrower for TDFL on both days 0 and 7. The results confirm the effectiveness of both types of laser in cutting and providing hemostasis in the lungs. TDFL caused less thermal damage to the lung parenchyma than DL.

Determination of initial airtightness after anatomical laser segmentectomy in an ex vivo model

If a pulmonary pathology can be removed by anatomical segmentectomy, the need for lobectomy is obviated. The procedure is considered oncologically equivalent and saves healthy lung tissue. In every segmentectomy, lung parenchyma must be transected in the intersegmental plane. Using an ex vivo model based on porcine lung, three transection techniques (monopolar cutter + suture, stapler, and Nd:YAG laser) are to be compared with respect to their initial airtightness. At an inspiratory ventilation pressure of 25 mbar, all three preparations were airtight. Upon further increase in ventilation pressure up to 40 mbar, the laser group performed best in terms of airtightness. Since thanks to its use of a laser fibre, this technique is particularly suitable for minimally invasive surgery; it should be further evaluated clinically for this indication in the future.

Local lung coagulation post resection: an ex-vivo porcine model

Following non-anatomical resection of lung parenchyma with a Nd:YAG laser, a coagulated surface remains. As ventilation starts, air leakage may occur in this area. The aim of the present study was to investigate, whether additional coagulation either before or after ventilation has an additional sealing effect. Freshly slaughtered porcine heart-lung blocks were prepared. The trachea was connected to a ventilator. Using a Nd:YAG laser (wavelength: 1320 nm, power: 60 W), round lesions (1.5 cm in diameter) with a depth of 1.5 cm were applied to the lung using an 800-μm laser fiber (5 s per lesion). Group 1 (n = 12) was control. Additional coagulation was performed in group 2 (n = 12) without and in group 3 (n = 12) with ventilation restarted. Air leakage (ml) from the lesions was measured. The thickness of each coagulation layer was determined on histological slices. Differences between individual groups were analyzed by one-way ANOVA (significance p < 0.05). After resection, 26.2 ± 2.7 ml of air emerged from the lesions per single respiration in group 1. Air loss in group 2 was 24.6 ± 2.5 ml (p = 0.07) and in group 3 23.7 ± 1.8 ml (p = 0.0098). In comparison to groups 1 and 2 thickness of the coagulation layers in group 3 was significantly increased. After non-anatomical porcine lung resection with a Nd:YAG laser, additional coagulation of the ventilated resection area can reduce air leakage.

Is laser-assisted resection preferable to lobectomy for pulmonary metastasectomy?

The aim of this study was to investigate if laser-assisted resection is appropriate for large and/or central lung metastases, when stapler wedge resection is not feasible, to determine whether this technique can be an alternative to lobectomy. All patients who underwent laser-assisted resection for large and/or central metastases were selected for the study. For comparison, patients who underwent lobectomy for metastases between 2005 and 2017 were reviewed. All resections were performed with a 1318-nm Nd:YAG laser. Perioperative features and long-term oncological outcomes were investigated. Some aspects and drawbacks of laser resection were also investigated. Among 89 patients, 42 (47%) underwent laser resection and 47 underwent lobectomy. Complete resection was achieved in 91% of laser resections and in 98% of lobectomies. The operative time, postoperative drainage time, and length of stay were significantly shorter in patients who underwent laser resection than in those who underwent lobectomy. Severe postoperative complications tended to be more frequent after lobectomy. The 5-year survival was 66% and 54% after laser resection and lobectomy respectively; the 5-year disease-free survival was 35% and 32% after laser resection and lobectomy respectively. No differences were found in long-term outcomes between the two techniques. Our experience showed that laser resection, when performed for large/central metastases, resulted in comparable survival and obtained better perioperative outcomes with respect to lobectomy. We believe that laser resection can be proposed as a reliable and advantageous lung-sparing technique, as an alternative to lobectomy for metastasectomy, when stapler wedge resection is not feasible.

Diode-pumped neodymium:yttrium aluminum garnet laser effects on the visceral pleura in an ex vivo porcine lung model†

OBJECTIVES

Resection of tumour spread on a very thin visceral pleura might be challenging, and collateral damage to the lung parenchyma might occur. We aimed to develop an operative technique, which might facilitate the parenchyma-sparing destruction of the visceral pleura. This experimental work investigated the effects of a neodymium:yttrium aluminum garnet (Nd:YAG) laser on the visceral pleura in an ex vivo porcine lung model.

METHODS

We used a diode-pumped Nd:YAG laser (Limax® 120, KLS Martin, Tuttlingen, Germany) to investigate the effects on the visceral pleural in 20 porcine lungs. The laser was applied on a standardized length in 4 different settings: Group I (80 W, 6 s), Group II (80 W, 12 s), Group III (120 W, 6 s) and Group IV (120 W, 12 s). All specimens were analysed histologically.

RESULTS

The mean thickness of the visceral pleura was 81 ± 10 μm. Increasing power levels and longer application duration resulted in significantly enhanced laser destruction effects. The mean depths of the carbonization zone were 142 ± 42 µm, 378 ± 137 µm, 607 ± 155 µm and 1371 ± 271 μm for Groups I-IV, respectively (P < 0.001). The ratio of carbonization zone to pleural thickness was measured for each section (C/P ratio) to quantify the thermal effects. The corresponding C/P ratio for Groups I-IV were 1.72 ± 0.55, 4.98 ± 1.96, 7.11 ± 1.61 and 17.35 ± 4.35, respectively (P < 0.001).

CONCLUSIONS

Our study showed that increasing power levels and application duration of the laser lead to a significantly increased carbonization and destruction zones. Further in vivo human studies should evaluate the feasibility of laser application for a potential translational relevance for human use.

Suturing of the laser resection area is recommended over a depth of 2 cm in an experimental porcine lung model

Background

Lung metastases can be removed by an Nd:YAG laser to save lung parenchyma. At these sites, a coagulated lung surface remains. Airtightness was investigated in relation to the depth of resection on an ex vivo porcine lung model.

Methods

Freshly slaughtered porcine double lung preparations were connected to a ventilator via a tube. Non-anatomical laser resections were performed with an 800 µm laser fiber and the Nd:YAG laser LIMAX^® 120 (power: 40 and 60 watts). The following resection depths (each n=12) from the lung surface were examined: 0.5, 1, 1.5 and 2.0 cm. After resection the lungs were submerged under water and ventilated (frequency 10/min, P_insp =25 mbar, PEEP =5 mbar). Airtightness of resection surfaces was determined by a leakage score, as well as the measurement of the leakage volume (in mL) per respiration (Group 1). Afterwards, the resection areas were coagulated for 5 seconds with a laser power of 60 watts at a distance of approximately 1 cm from the surface. This was followed by a re-evaluation for airtightness (Group 2). Finally, the resection surface was closed by a suture (PDS USP 4-0) and re-tested for airtightness (Group 3). The individual groups were compared for their significance (P<0.05) using a nonparametric test.

Results

Up to a resection depth of 1.5 cm, the ventilated resection surfaces were completely airtight regardless of the laser power. From a depth of resection of 1.5 cm, a mean air volume loss of 28.9±5.3 mL/respiratory cycle at 40 watts and of 26.4±5.8 mL at 60 watts was found. Additional surface coagulation did not significantly reduce the leakage rate. In contrast, suturing significantly reduced (P<0.0001) to 7.2±3.7 mL/ventilation (40 watts) and 6.0±3.4 mL/ventilation. At a resection depth of 2 cm, the leakage volume was 42.9±3.3 mL/respiratory cycle (40 watt) and 46.3±6.4 mL/respiratory cycle (60 watt). Additional surface coagulation failed to significantly reduce leakage volume, but suture closure provided airtightness.

Conclusions

In non-ventilated porcine lungs, Nd:YAG laser resection surfaces up to a resection depth of 1.5 cm are airtight after ventilation onset. From a depth of 1.5 cm, closure of resection surfaces by an additional suture is needed. Airtightness of resection surfaces was not increased by additional coagulation.

Autologous fat tissue grafting improves pulmonary healing after laser metastasectomy

BACKGROUND

Extensive clinical experience has demonstrated the potential usefulness of autologous fat tissue (AFT) graft in tissue reconstruction, repair or regeneration. In the present study, we evaluated the feasibility and safety of AFT in the repair of surgically injured lung surface.

METHODS

Eighty consecutive procedures of pulmonary metastasectomy by laser precision resection, were performed in 66 patients between March 2010 and December 2012. In the first 20 procedures, AFT graft was applied on the wounded pulmonary surface without closure of parenchymal surface. The following 40 procedures were carried on without AFT (20 leaving the resection margins open and 20 closing the resection margins with a running suture). In the remaining 20 procedures, AFT was applied and the resection margins closed. The efficacy of this technique was evaluated by comparing the AFT group with the non-AFT group, with respect to prolonged alveolar air leakage (PAAL), time to drain removal, length of hospital stay, and patient survival at four years.

RESULTS

The occurrence of PAAL was lower in the AFT group as compared to non-AFT group (17.5% versus 42.5%, p = 0.027), and median time to drain removal shorter (4 versus 6 days respectively, p = 0.016). Overall 4-year survival was 70% for AFT group, and 59% for non-AFT group (p = 0.34).

CONCLUSIONS

This prospective cohort observational study demonstrated the feasibility and safety of AFT pulmonary grafting after laser metastasectomy. AFT graft improved pulmonary healing, by reducing the incidence and severity of PAAL. Moreover, there was no evidence of tumor promotion in the metastatic setting, with a similar overall survival at 4 years.