Palsy of the recurrent laryngeal nerves in association with an ultrasonic activated device during thoracoscopic esophagectomy with three-field lymphadenectomy

Modification of the Thermal Spread by the Blade Shape of an Ultrasonically Activated Device

BACKGROUND

Few studies have focused on the spread of thermal damage from different blade shapes of ultrasonically activated devices (USADs) used during minimally invasive surgery.

METHODS

In vivo experiments using pig arteries, nerves, and mesentery were used to compare the thermal spread of two different blade types of USADs, non-tapered and tapered, under the same conditions. The tissue temperatures were monitored using a high-resolution infrared thermographic camera and calculated using an image analysis program. The spread of heat denaturation was measured histologically.

RESULTS

The temperature was greater at the sides with greater curvature when non-tapered USADs were activated (artery, 1 s, 2 mm: - 0.92 ± 0.5 °C vs. - 0.44 ± 0.5 °C, P = 0.022). This effect was more prominent in the tapered type (artery, 1 s, 0/1/2 mm: 9.14 ± 3.7 °C vs. 28.3 ± 16.2 °C/0.5 ± 1.4 °C vs. 9.76 ± 6.2 °C/ - 0.12 ± 0.9 °C vs. 1.44 ± 1.9 °C, P = 0.044/0.016/0.038, respectively). The temperatures in the tapered USAD were significantly higher at some time- and distance-points than those in a non-tapered USAD (artery, 1 s, 0 mm, Less/1 s, 1 mm, Gre: 4.2 ± 2.9 °C vs. 9.14 ± 3.7 °C /0.36 ± 0.5 °C vs. 9.76 ± 6.2 °C, P = 0.047/0.027; nerve, 2 s, 0 mm, Gre: 6.54 ± 3.9 °C vs. 17.66 ± 6.2 °C, P = 0.012). A three-directional study revealed the thermal spread of the mesentery was greatest at the tip side of the non-tapered type USAD (4.55 ± 2.53 °C vs. 12.43 ± 4.03 °C/12.43 ± 4.03 °C vs. 5.04 ± 1.91 °C, P = 0.003/0.005).

CONCLUSIONS

The thermal spread changed according to the blade shape of the USAD. This knowledge can be applied to more meticulous and complicated procedures, reducing surgical morbidity.

Lateral thermal spread and recurrent laryngeal nerve paralysis after minimally invasive esophagectomy in bipolar vessel sealing and ultrasonic energy devices: a comparative study

BACKGROUND

This study aimed to compare the extent of lateral thermal spread of surrounding tissues after the use of advanced bipolar and ultrasonic coagulation and shearing devices. Association between recurrent laryngeal nerve paralysis (RLNP) and such devices was assessed in patients who underwent minimally invasive esophagectomy (MIE).

METHODS

LigaSure^™ (LS) and Sonicision^™ (SONIC) were used. In ex vivo experiments using the porcine muscle, blade temperature and tissue temperature were measured using a thermometer after the activation of both devices. For the clinical assessment, 46 consecutive patients who received MIE were retrospectively assessed.

RESULTS

The temperature generated at the blade of both devices increased with the activation time. The blade temperature of LS was significantly lower than that of SONIC (P < 0.001). The blade temperature of SONIC exceeded 100 °C after 3-s activation. The temperature of surrounding tissues after a single activation of the devices decreased with the tissue distance from activation blade. The temperatures of tissues at 1 and 2 mm away from the blade side of LS were significantly lower than those of SONIC (P = 0.001 and P < 0.001, respectively). The temperature of tissue 2 mm away from the blade side of LS increased 6.4 °C from the baseline temperature. Furthermore, the incidence of RLNP in the LS group was lower than that in the SONIC group (P = 0.044).

CONCLUSION

This study highlights the necessity of spatial and temporal recognition of the thermal spread of coagulation and shearing devices to reduce the thermal injuries following MIE.