Efficacy of electrocoagulation hemostasis: a study on the optimal usage of the very-low-voltage mode.

BACKGROUND: The very-low-voltage (VLV) mode in electrosurgery can stably and deeply energize tissues even if the local electrical resistance changes with energization. Therefore, in electrosurgical hemostasis, the VLV mode is more reliable than other coagulation modes. In clinical practice, the appropriate use of combined saline drip and blood suction under the VLV mode can further enhance coagulation ability. However, the detailed mechanism is not known. The current study aimed to evaluate the association between electrosurgical activation time (ET) and hemostatic tissue effect (HTE) under the VLV mode. Further, the effect of saline drip and suction on power consumption and HTE was validated. METHODS: Twelve female pigs weighing 35 kg were included in the experiment. A liver hemorrhage model was established via an open abdominal procedure, and hemostasis in the hemorrhagic lesion was attempted using the VLV mode under different conditions (ET: 3, 6, 9, and 12 s, with/without saline drip and/or continuous suction). Electrical data (such as voltage, current, and resistance) during coagulation were extracted. Then, the vertical/horizontal extent of HTE was assessed, and the hemostasis outcome (successful or failed) was recorded. RESULTS: The vertical/horizontal HTE, power consumption, and integrated current value were positively correlated with the ET. The coagulation depth deepened with saline drip (p < 0.01). However, it was not affected by continuous suction (p = 0.20). The HTE area increased with saline drip (p < 0.01) and decreased with suction (p < 0.01). The power consumption and integrated current increased with saline drip (p < 0.01) and decreased with suction (p < 0.01). The success rate of hemostasis decreased with saline drip alone (31of 48 trials [success rate = 64.5%] in the saline drip group and 44/48 trials (success rate = 91.7%) in the control group). However, it improved with continuous suction (46/48 trials [success rate = 95.8%]). CONCLUSION: The electrosurgical activation time was positively correlated with hemostatic tissue effect. Saline drip increased heat transfer efficiency but decreased the success rate of hemostasis. Therefore, the use of continuous suction in addition to saline drip increased hemostatic efficiency.

A Novel Endoscopic Catheter for "Laparoscopy-Like" Irrigation and Suction: Its Research and Development Process and Clinical Evaluation.

BACKGROUND: Inspired by natural orifice translumenal endoscopic surgery (NOTES), the authors launched a development of novel endoscopic irrigation and suction (I/S) catheter for "laparoscopy-like" I/S in flexible gastrointestinal (GI) endoscopy. The aims were to describe its basic research and development (R&D) process and to estimate its performance in both preclinical and clinical settings. METHODS: In basic R&D phase, a layout of side hole at apex nozzle of endoscopic I/S (EIS) catheter were theoretically calculated and designed. Material of nozzle was selected based on the strength analysis. The performance of final prototype EIS catheter was then assessed preclinically in the porcine stomach, to compare with conventional endoscopic "tip irrigation" and "tip suction" as control. After regulatory clearance, safety and feasibility of I/S using EIS catheter were clinically assessed by endoscopists in small number of patients. RESULTS: Bench tests revealed 0.4 mm in diameter, 24 holes, and 6-8 holes per circumference as most suitable layout of side holes, and polyetheretherketone as an optimal nozzle material, respectively. Time to inject 500 mL saline with the EIS catheter was significantly shorter than tip irrigation (101 ± 3.1 seconds versus 154 ± 3.1 seconds; P < .05). The EIS suction was significantly weaker than conventional endoscopic tip suction, though it remained within the practical range. No mucosal injuries were noted in the EIS suction. In clinical assessments for human use, no adverse events were observed, and high degree of satisfaction for endoscopists was obtained. CONCLUSION: The newly developed EIS catheter is safely used with satisfactory performance in flexible GI endoscopy.