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

Refining postoperative monitoring of recurrent laryngeal nerve injury in esophagectomy patients through transcutaneous laryngeal ultrasonography

BACKGROUND

Recurrent laryngeal nerve injury (RLNI) leading to vocal cord paralysis (VCP) is a significant complication following minimally invasive esophagectomy (MIE) with upper mediastinal lymphadenectomy. Transcutaneous laryngeal ultrasonography (TLUSG) has emerged as a non-invasive alternative to endoscopic examination for evaluating vocal cord function. Our study aimed to assess the diagnostic value of TLUSG in detecting RLNI by evaluating vocal cord movement after MIE.

METHODS

This retrospective study examined 96 patients with esophageal cancer who underwent MIE between January 2021 and December 2022, using both TLUSG and endoscopy.

RESULTS

VCP was observed in 36 out of 96 patients (37.5%). The incidence of RLNI was significantly higher on the left side than the right (29.2% vs. 5.2%, P < 0.001). Postoperative TLUSG showed a sensitivity and specificity of 88.5% (31/35) and 86.5% (45/52), respectively, with an AUC of 0.869 (P < 0.001, 95% CI 0.787-0.952). The percentage agreement between TLUSG and endoscopy in assessing VCP was 87.4% (κ = 0.743).

CONCLUSIONS

TLUSG is a highly effective screening tool for VCP, given its high sensitivity and specificity. This can potentially eliminate the need for unnecessary endoscopies in about 80% of patients who have undergone MIE.

Short-term and long-term effects of recurrent laryngeal nerve injury after robotic esophagectomy

BACKGROUND

Robot-assisted minimally invasive esophagectomy (RAMIE) was reported to have superiority in upper mediastinal lymph nodes dissection than traditional approach, but related injuries to recurrent laryngeal nerve (RLNI) cannot be avoided. Considering that there is no study centering on RLNI during robotic manipulation, this study aimed to investigate the impact of RLNI on the short-term and long-term outcomes after RAMIE.

METHODS

Patients with esophageal cancer (EC) who underwent RAMIE from June 2015 to July 2019 were collated from a prospectively maintained database. Short-term and long-term outcomes of RLNI were analyzed.

RESULTS

A total of 409 patients were included with the incidence of RLNI being 18.6% (76/409). A higher rate of postoperative pulmonary complications including pneumonia (P < 0.001) and acute respiratory distress syndrome (ARDS) (P = 0.041) was associated with RLNI, requiring more interventions for bronchoscopy airway suction (P < 0.001), tracheal reintubation (P = 0.013) and tracheostomy (P < 0.001). Patients with RLNI had a prolonged length of hospitalization and intensive care unit (ICU) stay (P < 0.001). With the median follow-up time of 48.7 (interquartile range [IQR]:27.6-60.9) months, recurrence in regional lymph nodes at mediastinum did not differ between groups (P = 0.351). Similarly, the Kaplan-Meier curves revealed no significant divergency for overall survival after RLNI (P = 0.452).

CONCLUSIONS

RLNI after robotic esophagectomy is a serious morbidity associated with an increased rate of pulmonary complications, prolonged length of hospitalization with limited influence on long-term prognosis.

Detection of the Lateral Thermal Spread during Bipolar Vessel Sealing in an Ex Vivo Model-Preliminary Results

Background: As an unwanted side effect, lateral thermal expansion in bipolar tissue sealing may lead to collateral tissue damage. Materials and Methods: Our investigations were carried out on an ex vivo model of porcine carotid arteries. Lateral thermal expansion was measured and a calculated index, based on thermographic recording and histologic examination, was designed to describe the risk of tissue damage. Results: For instrument 1, the mean extent of the critical zone > 50 °C was 2315 ± 509.2 µm above and 1700 ± 331.3 µm below the branches. The width of the necrosis zone was 412.5 ± 79.0 µm above and 426.7 ± 100.7µm below the branches. For instrument 2, the mean extent of the zone > 50 °C was 2032 ± 592.4 µm above and 1182 ± 386.9 µm below the branches. The width of the necrosis zone was 642.6 ± 158.2 µm above and 645.3 ± 111.9 µm below the branches. Our risk index indicated a low risk of damage for instrument 1 and a moderate to high risk for instrument 2. Conclusion: Thermography is a suitable method to estimate lateral heat propagation, and a validated risk index may lead to improved surgical handling.

Improving Outcome of Superior Mediastinal Lymph Node Dissection During Esophagectomy: A Novel Approach Combining Continuous and Intermittent Recurrent Laryngeal Nerve Monitoring

OBJECTIVE

This study aimed at demonstrating the effects and learning curve of utilizing combined intermittent and continuous recurrent laryngeal nerve (RLN) monitoring for lymphadenectomy during esophagectomy.

BACKGROUND

RLN lymphadenectomy is oncologically important but is technically demanding. Vocal cord (VC) palsy as a result from RLN injury, carries significant morbidities.

METHODS

This is a retrospective study of consecutive esophageal squamous cell carcinoma (ESCC) patients who underwent transthoracic esophagectomy from 2010 to 2020. Combined nerve monitoring (CNM) included: CNM which involved a periodic stimulating left vagal electrode and intermittent nerve monitoring which utilized a stimulating probe to identify the RLNs. The integrity of the RLNs was assessed both intermittently and continuously. This technique was introduced in 2014. Patients were divided into "before CNM" and "CNM" groups. The primary outcome was the difference in number of RLN lymph nodes harvested and VC palsy rate. Learning curves were demonstrated by cumulative sum (CUSUM) analysis.

RESULTS

Two hundred and fifty-five patients were included with 157 patients in "CNM" group. The mean number of RLN lymph nodes harvested was significantly higher (4.31 vs 0.45, P < 0.0001) for the "CNM" group. VC palsy rates were significantly lower (17.8% vs 32.7%, P = 0.007). There was an initial increase in VC palsy rate, peaked at around 46 cases. The increase in lymph nodes harvested above the mean plateaued at around 96 cases.

CONCLUSIONS

CNM helped improve bilateral RLN lymphadenectomy. Lymph node harvesting was increased with reduction of VC palsy after a learning curve.

Diagnosis of recurrent laryngeal nerve paralysis following esophagectomy by evaluating movement of the vocal cords and arytenoid cartilages using ultrasonography

Advancements in thoracoscopic surgery have provided us with a deeper anatomical understanding of recurrent laryngeal nerve paralysis (RLNP), which is likely to occur after lymph node dissection. Taking a novel approach to researching the diagnosis of RLNP, we evaluated movement of the vocal cords and arytenoid cartilages using ultrasonography in patients who underwent thoracoscopic esophagectomy. RLNP occurred in six of the 24 patient cohort. The rate of hoarseness and difficulty in discharging sputum was significantly higher in the paralyzed group than in the non-paralyzed group. The diagnostic accuracy of RLNP by ultrasonography had a sensitivity of 83.3% (5/6), a specificity of 88.8% (16/18), a false positive rate of 5.6% (1/18), and a false negative rate of 0% (0/6). Although it is not completely accurate, our findings indicate that ultrasonography is quite effective for diagnosing RLNP, more so in combination with clinical symptoms. Ultrasonography may also be effective for identifying patients who are amenable to laryngoscopy for diagnosing RLNP, or for evaluating the recovery status of nerve paralysis.

Optimization of robot-assisted thoracoscopic esophagectomy in the lateral decubitus position

BACKGROUND

On the introduction of robot-assisted thoracoscopic esophagectomy (RATE), we refined the robotic system application to enhance our surgical experience obtained through thoracoscopic esophagectomy (TE) in the lateral decubitus position (LDP). Herein, we evaluate our methods introduced to optimize RATE in the LDP.

METHODS

We performed RATE in the LDP with camera rotation and manual hand control assignment to reproduce the surgical view and manipulation of open esophagectomy. Forty patients underwent RATE between July 2018 and August 2020. After the initial 30 cases (initial RATE group), we optimized the port arrangement and robot settings in the most recent ten cases (recent RATE group). The surgical results of RATE were compared with those of 30 patients underwent TE between April 2014 and May 2019 selected by propensity score-matched analysis based on cStage (TE group).

RESULTS

Operative duration was significantly longer in the initial RATE group than the TE group and the recent RATE group. Thoracic blood loss was significantly less in the initial RATE group than the TE group. Console time was significantly shorter in the recent RATE group than the initial RATE group. There was no surgical mortality in RATE and the surgical morbidity rate was similar in the three groups.

CONCLUSIONS

Camera rotation and manual hand control assignment during RATE in the LDP reproduced the surgical view and manipulation of open esophagectomy and TE in the LDP. The robotic platform enabled meticulous dissection and reduced blood loss, but was initially time-consuming. Optimization of the port arrangement minimized operative duration.

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.

Assessment of Quality Outcomes and Learning Curve for Robot-Assisted Minimally Invasive McKeown Esophagectomy

BACKGROUND

This study aimed to identify the results of the quality assessment and the learning curve of robot-assisted minimally invasive McKeown esophagectomy (RAMIE-MK).

METHODS

The study retrospectively reviewed the data of 400 consecutive patients with esophageal cancer who underwent RAMIE-MK by a single surgeon from November 2015 to March 2019. Cumulative summation analysis of the learning curve was performed. The patients were divided into decile cohorts of 40 cases to minimize demographic deviations and to maximize the power of detecting statistically significant changes in performance.

RESULTS

The 90-day mortality rate for all the patients was 0.5% (2 cases). The authors' experience was divided into the ascending phase (40 cases), the plateau phase (175 cases), and the descending phase (185 cases). After 40 cases, significant improvements in operative time (328 vs. 251 min; P = 0.019), estimated blood loss (350 vs. 200 ml; P = 0.031), and conversion rates (12.5% vs. 2.5%; P < 0.001) were observed. After 80 cases, a decrease in the rates of anastomotic leakage (22.5% vs. 8.1%; P = 0.001) and vocal cord palsy (31.3% vs. 18.4%; P = 0.024) was observed. The number of harvested lymph nodes increased after 40 cases (13 vs. 23; P < 0.001), especially for lymph nodes along the recurrent laryngeal nerve (3.0 vs. 6.0; P < 0.001).

CONCLUSIONS

The learning phase of RAMIE-MK consists of 40 cases, and quality outcomes can be improved after 80 procedures. Several turning points related to the optimization of surgical outcomes can be used as benchmarks for surgeons performing RAMIE-MK.

Lymph node dissection and recurrent laryngeal nerve protection in minimally invasive esophagectomy

Until now, neoadjuvant therapy plus surgical resection of the primary tumor and potential metastatic lymph nodes (LNs) has been the current optimal treatment for locally advanced thoracic esophageal cancer (EC). LN metastasis is one of the most negative prognostic factors for thoracic esophageal squamous cell carcinoma (ESCC). However, the extent of LN dissection for thoracic ESCC has long been controversial worldwide. LNs along the recurrent laryngeal nerve (RLN) were reported to have the highest frequency of metastases in thoracic ESCC, so lymphadenectomy along the bilateral RLN is necessary but quite challenging because of a high frequency of recurrent nerve palsy and related postoperative complications. With the development of minimally invasive devices and techniques in recent years, minimally invasive esophagectomy (MIE) has been widely applied in EC surgery. The topics of what the optimal extent of lymphadenectomy is and how the recurrent nerve should be well protected during MIE have been debated in recent years. The purpose of our review is specifically to address the patterns of LN metastasis, the extent of LN dissection, and the protection of the RLN in MIE for thoracic ESCC.