Evaluation of the safety and efficacy of suction-tip forceps, a new tool for laparoscopic surgery, in patients with gastric cancer: Preliminary results from a prospective trial

Background Laparoscopic surgery is widely accepted as minimally invasive surgery; however, obstacles to its functional optimization remain. One such challenge is that each surgical port can accommodate only one instrument at a time. Complex manipulations are therefore necessary to exchange one laparoscopic tool with another during surgery (e.g., removal of forceps and placement of a suction tube), which increases operation times and risk to patients. We developed a new laparoscopic instrument that functions as both forceps and a suction tube, which renders intraoperative tool exchange unnecessary. This prospective pilot study was undertaken to evaluate the safety and efficacy of this novel dual-function device in laparoscopic surgery for gastric cancer. Methods This single-center prospective pilot study was undertaken with 15 patients who required laparoscopic distal gastrectomy for gastric cancer. To assess patient safety, intraoperative video was used to document any tissue damage associated with the new instrument. To evaluate instrument efficacy, we measured the time interval between the start of bleeding and the start of aspiration (“suction access time”) and compared this time with that of a conventional surgical setup. Results All procedures were successful, and no excess tissue damage occurred during surgery with the suction-tip forceps. Bleeding occurred 158 times. Suction access time was significantly shorter in cases of bleeding when the suction-tip forceps were used (2.01 seconds) than when an ordinary suction tube was used for aspiration (12.5 seconds; P < 0.01). Conclusion These findings suggest that our new suction-tip forceps are a useful, safe, and efficacious operative tool. This surgical innovation may considerably simplify gastric laparoscopic surgery. This pilot study was registered with Japan Clinical Trial Registration on June 22, 2017 (registration number: UMIN000027879).


Introduction
Since 1994, when Kitano et al. first reported successful laparoscopy-assisted gastrectomy [1], this technique has been widely adopted as a less invasive operative procedure for gastric cancer. However, in comparison with open surgery, laparoscopic surgery is more technically complex and tends to take more time [2][3][4][5]. One reason for this is that each surgical port in the abdominal cavity is able to accommodate only one surgical instrument at a time. When bleeding inevitably occurs during laparoscopic surgery, the surgeon must temporarily withdraw the ultrasonic laparoscopic coagulation shears (LCS) and substitute them with a suction tube for blood aspiration. This one-handed substitution is somewhat complex and takes time. If a substitution period takes too long, small intra-operative bleeding is likely to penetrate the surrounding tissue, which discolors the surrounding tissues with a reddish hue making identification of dissection layers difficult even after blood aspiration [6]. To address this limitation, here is one surgical tool, composed of the conventional forceps (inserted through an incision) and connected with an external suction tube, developed for use in uniportal video-assisted thoracoscopic surgery [7].
However, that tool could not be inserted through a 5-mm diameter port, which is standard in laparoscopic surgery; furthermore, it is not designed for free rotation.
To better address the practical challenges of laparoscopic surgery, we developed a novel type of forceps that is inlaid with a suction tip for simultaneous aspiration. During surgery, the surgeon can use these suction-tip forceps with one hand to begin aspiration as soon as bleeding occurs and, without changing instruments, use the LCS in the other hand to coagulate the origin of bleeding. Our instrument is the first of its kind to be narrow enough for insertion into the standard 5-mm port standard used in laparoscopic surgery, to function as both forceps and as a suction device, and to have 360-degree rotational capacities. This prospective single-center pilot study was undertaken to evaluate the safety and efficacy of this tool in a real-world setting. Forceps and suction tubes for laparoscopic surgery are very basic tools that have demonstrated safety that is widely recognized. Therefore, our suction-tip forceps, which combines these two treatment modalities, was considered safe for human research and was approved by our institution's ethics committee.

Patients And Methods
Between June 2017 and April 2018, 15 patients with gastric cancer underwent laparoscopic surgery with the suction-tip forceps at Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan.
Because this was a feasibility study, power analysis to calculate sample size was not necessary. The study protocol was reviewed and approved by the institutional review board of Nippon Medical School Chiba Hokusoh Hospital (Ethics Committee of Nippon Medical School Chiba Hokusoh Hospital, Approval No. 583). All patients who were older than 20 years, were not suitable candidates for endoscopic mucosal resection or endoscopic submucosal dissection, and were judged to be candidates for laparoscopic treatment, were approached for participation in this study. Participants provided written informed consent prior to surgery. Additionally, this study was registered in Japan Clinical Trial Registration database (registration number: UMIN000027879) with the title: Safety Examination of Endoscopic Surgical Forceps which can Absorb at the Tip. It adheres to CONSORT guidelines appropriate for non-randomized pilot studies.

Suction-tip forceps
The suction-tip forceps (Hope Denshi Co., Ltd., Chiba, Japan) used in this study can be smoothly inserted and withdrawn through ordinary 5-mm surgical ports. They have an inlaid 2.5-mm suction tunnel, and thus are capable of aspirating matter from the tip of the forceps' jaws to the handle ( Fig. 1a and f) for evacuation via a vacuum system. If the jaws are closed, a 2.5-mm diameter tunnel is formed between the jaws (Fig. 1b, c and f), and blood can be aspirated from this tip (Fig. 1b, c and g). If the jaws are open, surgical mist can be aspirated from the pivot joint to the handle (Fig. 1d, e, and h).

CO 2 insufflation and foot-controlled suction system
A UHI-4 device (Olympus Medical Systems, Tokyo) was used to perform abdominal insufflation. This device is designed to provide CO 2 when the foot pedal is pushed in the event of mist or smoke discharge in the surgical field. In our setup (modified from Shinsuke S et al. [8]) one end of the discharge tube was connected to a negatively pressurized suction bottle and the other end was connected to an outlet above the handle of the suction-tip forceps. In this way, we created a system by which negative pressure could be applied to the suction-tip forceps when the foot pedal is pushed, which allows aspiration of mist or smoke, as well as blood, through the tip of the forceps (Fig. 2). A conceptual schematic of suction-tip forceps use is shown in Fig. 3.

Operative procedure
All surgical procedures were conducted by three surgical specialists (NS, JH, and FA). In the event of bleeding, blood was aspirated with suction-tip forceps held in the operator's left hand. Simultaneously, the operator used the right hand to establish hemostasis with cauterization via the LCS. While the suction tip forceps were used by default during surgeries, in cases of massive bleeding or other complications, the operator occasionally withdrew the LCS (with the right hand) and replaced it with an ordinary suction tube that had a monopolar soft-coagulation tip for hemostasis.
Our intraoperative approach was as follows: gastrocolic ligaments were dissected with the LCS so as to enter the omental bursa. The left gastroepiploic artery and vein were then identified, clipped, and dissected. Next, the right gastroepiploic vein and artery were identified, clipped, and dissected. The duodenum was dissected with a stapler. After that, the right gastric artery and vein were identified, clipped, and dissected. The 8a lymph nodes along the common hepatic artery were then excised. Next, the left gastric artery was double-clipped and dissected. The stomach was dissected with a stapler (distal gastrectomy). This wound in the umbilical region was dilated to 4 cm, and specimens were removed. The residual portion of the stomach was anastomosed to the duodenum (Billroth-I, delta anastomosis). Finally, after washing of the surgical cavity and confirmation of hemostasis, a drain was inserted into the anastomosed area, and the abdomen was closed.

Endpoints
To evaluate the clinical safety of the new suction-tip forceps, outside experts (HA, KK, SM, and YK) independently reviewed the surgical video to detect any unnoticed damage that may have occurred during used (e.g., tearing or piercing of tissue); they did not attend any surgeries in-person. Postoperative complications were evaluated according to the Clavien-Dindo classification [9,10].
To evaluate the efficacy of the suction-tip forceps, we assessed suction access time, defined as the time interval between the start of bleeding and the start of aspiration. We compared suction access time as when the suction-tip forceps were used with that of the conventional substitution technique (withdrawal of the LCS with the surgeon's right hand, switching to an ordinary suction tube, and reinsertion into the source of bleeding). Use of the suction-tip forceps was the default method during surgery; the conventional method was used in certain situations as judged by the operator (e.g., when LCS alone could not stop bleeding properly and extra suction stabilization was required). From data analysis, we excluded cases in which both suction methods were used for one bleeding instance.

Statistical analysis
Statistical analysis was performed with the R software suite (version 3.3.2; The R Foundation for Statistical Computing, Vienna). The distribution of data was not normally distributed as determined by Kolmogorov-Smirnov test, so we assessed the data by using the Mann-Whitney test. A P level of >0.05 was regarded as indicative of statistical significance. Table 1 lists the characteristics and surgical outcomes of 15 patients with gastric cancer who underwent laparoscopic distal gastrectomy in this trial. The mean age of the patients was 72.5 years, the mean length of surgery was 244.3 minutes, and the mean amount of blood loss was 18.0 g. The length of hospitalization after the surgery had a mean of 12.9 days and the mean length of follow-up after discharge was 17.3 months. Histopathological and radiological evaluation of the tumors revealed stage IA cancer in nine cases, stage IB in four cases, and stage IIB in two cases. In all cases, R0 surgery was successful (Table 1).

Patient characteristics and surgical outcomes
Only one non-related post-surgical complication occurred out of 15 surgical cases; patient no. 5 developed a Clavien-Dindo postoperative complication (grade 3). This patient had a history of previous heart failure with angina pectoris, and postoperative computed tomography showed no abnormalities such as pancreatic fistula or leakage in the abdomen after surgery. It was concluded that this complication was diagnosed as pleural effusion caused by worsening of heart function, not by intra-abdominal surgery. It was alleviated with thoracic drainage. This patient later died of heart failure 12 months after surgery.
Another case, patient no. 3 died from cerebral hemorrhage 16 months after surgery; the remaining 13 patients remained stable without disease recurrence through June 2019. poorly differentiated adenocarcinoma (non-solid type); Sig: signet ring cell carcinoma; Tub 1: well-differentiated tubular adenocarcinoma. Tub 2: moderately differentiated tubular adenocarcinoma. When used gauzes were dry and aspiration bottle was empty, we estimated the final blood loss as 10 g to account for blood remaining in the transparent vinyl tube connected to the suction bottle.

Safety of the suction-tip forceps
There was no tissue damage observed by the suction-tip forceps according to independent video analysis.

Efficacy of the suction-tip forceps for aspiration of bleedings
There were a total of 158 bleeding instances in 15 patients. As seen in Fig. 4, these instances of bleeding were divided into 111 in which only the suction-tip forceps were used, 38 in which only substitution with an ordinary suction tube was used, and 9 in which both methods were used (not included in analysis). Suction access time with the suctiontip forceps was compared with the suction access time for the conventional method (replacement of the LCS with an ordinary suction tube). The medians were 2.01 seconds (range: 0.28 to 9.29 seconds) and 12.5 seconds (range: 5.53 to 32.2 seconds), respectively (P < 0.01).
For hemostasis of the 158 bleeding instances, aspiration was performed with the suctiontip forceps without any further manipulation (no further bleeding after aspiration) in 37 such instances; hemostasis was achieved with LCS use soon after aspiration with the suction-tip forceps in 47 instances; compressive hemostasis was needed after aspiration with the suction-tip forceps in 24 instances; clipping was necessary in three instances; and the suction-tip forceps required follow-up treatment with an ordinary suction tube to achieve hemostasis in 47 instances (Fig. 4). The suction-tip forceps could aspirate volumes of blood ranging from small to massive (Fig. 5 and 6).
Qualitatively, the suction-tip forceps quickly and effectively evacuated the surgical mist created by the LCS in the surgical field many times, according to video analysis (Fig. 7).

Discussion
This is the first report of a new surgical forceps design. This novel tool has a tip that is capable of intraoperative aspiration, can be passed through a 5-mm port and can be rotated 360 degrees without restriction.

Safety of the suction-tip forceps
Our analysis showed that the use of this type of forceps in laparoscopic gastrectomy was technically feasible and R0 surgery was accomplished in all 15 cases. No complications or tissue damage associated with the use of the suction-tip forceps were observed in any patient.

Efficacy of the suction-tip forceps
In laparoscopic gastrectomy, five ports are usually employed; the operator holds the LCS with the right hand and the forceps with left hand, the assistant holds the forceps with both hands, and the scopist holds a laparoscope at the umbilical port [11]. When aspiration is needed to address bleeding or exudate, the operator usually withdraws the LCS and inserts a suction tube via a port. The suction-tip forceps designed by our team has an inlaid suction tube. This allows for immediate aspiration upon detection of bleeding (median time: 2.01 seconds; number of instances of bleeding: 111; Fig. 4), without the need for substitution with another suction tool. In the conventional surgical technique (replacement of the LCS in the right hand with an ordinary suction tube upon the detection of bleeding) mandated a median of 12.5 seconds before aspiration could be started (in 38 cases; Fig. 4). The suction-tip type of forceps allowed aspiration to be started more rapidly after the onset of bleeding and also reduced the complexity of intra-surgical manipulations; namely, replacement of the LCS held in the right hand with a suction tube.
Without the need to perform a complex instrument substitution, operational stress is significantly reduced as well.
The measures taken after bleeding are shown in Fig. 4. There were 37 additional instances of bleeding that were minor or in which the blood pool was very small and did not necessitate hemostasis after aspiration. In the case of sudden massive bleeding, a surgeon was able to begin aspiration with the left hand as quickly as 0.28 seconds with the suction-tip forceps after detection of bleeding. The operator was able to address bleeding with suction-tip forceps in 111 (70.3%) of 158 instances of intraoperative bleeding without the need for coagulation with an ordinary suction tube. The remaining 47 instances of intraoperative bleedings were addressed with an ordinary suction tube that we used with a monopolar soft-coagulation at the tip [12][13][14], because the suction-tip forceps did not have a coagulation function.

Aspiration of mist and smoke
The mist and smoke (mixed) generated from the LCS and moisture during surgery can obscure the surgical field of vision [15,16]. Surgical smoke has been reported to be hazardous to physicians, nurses, and other medical staff involved in the operation if it escapes from the patient's body [17,18], but it also has adverse effects on the patient, if it spreads within the peritoneal cavity as mist [19]. We observed that the suction-tip forceps aspirated any surgical gases created by moisture in the intraoperative field many times during video analysis. This evidence suggests that the suction-tip forceps can aspirate both gas (mist in Fig. 7) and liquid (blood and leachate in Figs. 5 and 6), thereby consistently maintaining a clear surgical field.

Distance from mist origin
During conventional laparoscopic surgery, mist that has spread within the peritoneal cavity is ventilated with a smoke extraction apparatus. The surgical ports are the point of evacuation but only after the mist has spread from the tip of LCS and obstructed the surgical field. Mist can be aspirated more efficiently if the aspiration is performed close to the point of origin of the mist before it diffuses within the peritoneal cavity [20,21].
Aspiration of intraoperative mist with the suction-tip forceps is advantageous in terms of the proximity to the origin of the mist. The distance from LCS's tip to port (conventional evacuation setting) is far longer than that for the suction-tip forceps tip nearby in the surgical field (Fig. 8). If the suction-tip forceps is held with the left hand, the mist and smoke generated from the LCS held with the right hand can be aspirated at a very short distance, thus efficiently improving the visual field, and absorption of the surgical smoke may be more efficient.
One limitation of this study was that it was conducted at a single center. In addition, the number of treated patients and instances of bleeding were small, which limited statistical power. Finally, the assessment of surgical mist cleared by our tool remains anecdotal.    Results of different approaches to controlling bleeding.    operator's right hand; STF: suction-tip forceps.