We focused on comparing the traditional monopolar electric hook and the advanced ultrasonic Harmonic ACE Plus® dissector for VATS lung lobectomy and lymphadenectomy for non-small cell lung cancer. For these two devices we analyzed safety of use during the surgical procedure and potential impact on postoperative short-term outcomes in terms of complications, postoperative drainage fluid production and chest tube removal.
In our cohort no intraoperative complication due to energy devices were recorded, confirming the rarity of these injuries (1–2 cases per 1,000 surgical procedures) . Thermal burn is the most common cause of instrument-related injury and death during surgery and it is correlated with the device lateral thermal spread [13–17]. Monopolar electrocautery is generally associated with greater heat spread, however in our cohort no clinically relevant lesions to nerves or vessels occurred during surgery [13–17]. This suggests that surgeon awareness of energy device technology, application and common injury patterns, and the use of protected-tip cautery, may minimize complications related to energy-based instruments application for VATS lobectomy and lymphadenectomy [14,16].
Postoperatively, no statistically significant difference of chylothorax incidence, chest tube duration and length of stay was detected between electric hook and Harmonic ACE Plus®, despite the increased postoperative pleural drainage in the ultrasonic dissector group that was not confirmed in the matched cohort. Moreover, energy device was not recognized as an independent risk factor of increased postoperative pleural effusion volume, and of prolonged chest tube duration.
Lack of significant differences in postoperative chylothorax and hemothorax incidence between monopolar electrocautery and ultrasonic dissector are consistent with results reported in the literature. Martucci et al., in their prospective randomized study of 119 patients undergoing open lung lobectomy and lymphadenectomy observed a similar postoperative chylothorax rate using the conventional electrocautery or the Ligasure™ (1.61% vs 1.75%, p-value = 1.00) . Likewise, Yoshida et al. in their retrospective cohort of 112 patients did not detect any significant difference in terms of chylothorax incidence when small vessels division and lymph node dissection were performed by manual ligature and conventional electrocautery or by Ligasure™ (1.8% vs 0%; p-value = 1.00) . However, in our study and in that of Yoshida et al., chylothorax rate was slightly higher after using blunt instruments and electrocautery than with the vascular-sealing device. These results could be explained by the mechanical principles underlying the two techniques. In contrast to electrocautery sealing by heat coagulation only, the Harmonic ACE Plus® combines heating and instrument blades mechanical pressure, fusing vessels walls and producing a permanent seal for vessels up to 5 mm [3–8,14,16,18,19]. This sealing ability should prevent any oozing or lymphatic leak. However, the low incidence of chylothorax and the absence of statistically significant difference between the two groups suggest that careful use of electric hook can also lead to satisfying results in terms of lymphatic leakage control.
In our series the total amount of pleural effusion volume collected at 48 hours after surgery was significantly higher after using the ultrasonic than the monopolar dissector. This result is in contrast with previous literature reports. Toishi et al., in their randomized study including 58 patients undergoing VATS lung lobectomy and lymph node dissection, reported significantly higher postoperative drainage volume when blunt dissection, manual ligature and/or electrocautery were preferred to vessels-sealing devices (Harmonic ACE Plus®, LigaSure™ and Enseal®) (613 ± 320 vs 437 ± 213 ml at 48 hours; p-value = 0.0358) . Similar results were reported by Yoshida et al. comparing conventional tissue dissection and vascular ligation to the use of LigaSure™ (postoperative drainage at 72 hours: 705.3 ± 339.3 vs 533.8 ± 264.8 ml; p-value < 0.05) . In our study, the concurrence of other variables may explain the increased postoperative pleural effusion production with the Harmonic ACE Plus®. In fact, the multivariable analysis identified lower lung lobectomies and increased surgery duration, but not energy device as risk factors for increased pleural effusion volume at 48 hours after surgery. Moreover, after matching patients by gender, site of resection and surgeon, these differences were annulled.
Regarding chest tube duration, no differences were detected between electric hook and Harmonic ACE Plus® in our study, even when energy device variable was adjusted for other possible risk factors for late chest tube removal at multivariable analysis. Thus, beside the two cases of chylothorax in monopolar electrocautery group and the larger amount of postoperative pleural drainage in Harmonic ACE Plus® group, the use of one or the other instrument revealed a similar impact on postoperative chest tube duration. These findings are supported by the report of Schuchert et al., who did not observe any differences in terms of postoperative outcomes when Ligasure™ was used in 211 open and VATS anatomical lung resections . No difference in chest tube removal timing has also been reported by Martucci et al. . Conversely, Toishi et al. and Yoshida et al. reported earlier chest tube removal when vessel-sealing devices were used [4,5]. These differences could also be explained by the fact that vessel-sealing devices were not the same in the mentioned studies [4,5,9,10]. Data about postoperative prolonged air-leak, a relevant factor of delayed chest tube removal, were not reported [4,5].
Surgical procedures lasted longer in the Harmonic ACE Plus® group of our series, while previous studies did not observe any differences in the length of surgery using vessel-sealing instruments [4,5]. Considering these observations and our long-term favorable experience with Harmonic ACE Plus®, longer duration of surgery in the ultrasonic dissector group is probably not due to the device itself but to the higher (almost double) proportion of lower lung lobectomies performed using this device type (p-value = 0.005); no difference of surgery duration was detected in the matched cohort.
Finally, in terms of costs, Harmonic ACE Plus® is not disposable and is more expensive than the electric hook, which is also reusable; cost is about fourfold (~ 130 vs 500 Euros) in our institution. Thus, in the absence of documented Harmonic ACE Plus® greater impact on the surgical procedure and on postoperative short-term outcomes, electric hook may be preferred with the aim of saving direct cost of the energy device. However, ultrasonic device sealing ability could reduce the use of endoscopic staplers and ligating clips, that are also costly, and may impact on overall surgical costs [9,14,16,18,20].
This study has several limitations. First, it is an observational study with the choice of electric hook or Harmonic ACE Plus® left to surgeon’s preference. Nevertheless, we performed multivariable analysis and propensity score matching analysis to partly overcome the lack of randomization. Second, we did not analyze the Harmonic ACE Plus® performance in sealing small vessels up to 5 mm, because surgeons in our team preferred to employ endoscopic staplers or clips to close vessels not suitable for coagulation. A strength of this observational study is the evaluation and comparison of electric hook and Harmonic ACE Plus® performance in the real-world daily practice of VATS major lung resections.