VTS have been used in patients with gastrointestinal, gynecologic, and urologic diseases, and it is proven safe and feasible with no increase in overall complication rates. However, studies involving VTS in bariatric surgery are very rare. Physiologically, morbidly obese patients have a higher intra-abdominal pressure at 2 to 3 times that of non-obese patients. Therefore, higher pressure of CO2 pneumoperitoneum may be required to create a well-exposed surgical view, which increase not only the risk of bradycardia and subcutaneous emphysema but also CO2 absorption by the patient and the value of EtCO2.[7, 10] Herati et al. showed that the use of the VTS significantly reduced CO2 absorption during laparoscopy renal surgery when compared with the standard trocar. However, there was no difference in bradycardia and EtCO2 regarding laparoscopic bariatric surgery in our study.
VTS provides a stable pneumoperitoneum with continuous smoke extraction, allowing surgeons to focus on surgical details rather than being distracted by smoke-block visualization, smudged camera, or loss of insufflation. Theoretically, optimization of operative time is one of the advantages of VTS. However, a systemic review showed that the impact of VTS in terms of operative time was not significantly different for the majority of studies. Only four studies that investigated urologic surgeries such as prostatectomy or nephrectomy, including three robotic procedures and one laparoscopic procedure reported significantly shorter mean operative time of VTS than conventional trocar insufflation.[6, 11–13] This observed difference in operative time in various surgical fields may be due to the following reasons: (1) above-mentioned urologic surgeries require frequent instrument changes and (2) more intraoperative bleeding resulting in increased frequency of electrocautery and suction. These conditions highlight the role of VTS in keeping stable pneumoperitoneum and continuous smoke suction. In our study, as there was no significant difference in operative time between groups, we postulate that it may be related to less bleeding as in bariatric surgeries. Surgical field was easily maintained in both groups because suction and electrocautery were not frequently needed. Therefore, the effects of VTS on operative time and blood loss were not significant.
Despite no significant difference in operative time between groups in our study, a better visualization was noted in the VTS group especially when using energy devices. There was seldom sudden decrease of intra-abdominal pressure in the VTS group, which disrupted the surgical exposure and affected surgical performance. VTS enabled lower intra-abdominal pressure to perform laparoscopic surgery. However, a systematic review on gynecological surgery showed that low-pressure laparoscopic surgery was associated with decreased surgical field, which can increase the risk of complications.
Since VTS provides lower and more stable pressure of pneumoperitoneum, postoperative shoulder pain is another commonly discussed subject. Shoulder pain is a multifactorial symptom possibly related to the irritative effect of CO2 and diaphragmatic stretching. A systematic review on low-pressure versus standard-pressure pneumoperitoneum during laparoscopic cholecystectomy showed significant reductions in shoulder pain and analgesic requirements in low-pressure group. Sroussi et al. conducted a randomized controlled trial and reported that the incidence of shoulder pain was significantly lower in the VTS group. However, lower intra-abdominal pressure with 7 mmHg was used in VTS group compared to control group with 15 mmHg pneumoperitoneum. Another randomized controlled trial used equal intra-abdominal pressure (12 mmHg) in the VTS and control groups and revealed an unexpected result that the VTS group had higher shoulder pain. They assumed that it might be due to the constant pressure pneumoperitoneum compared to the standard insufflator where the pressure changes during some maneuvers such as suction. In our study, an equal intra-abdominal pressure (12 mmHg) was established. All the patients underwent the same strategy of using a low flow rate to induce pneumoperitoneum followed by a high-flow rate to maintain the pressure. This strategy can reduce the severity of shoulder pain, compared with continuous high-flow rate insufflation in laparoscopic cholecystectomy. There was no significant difference in the incidence and severity of shoulder pain between groups. However, the analgesic agents, which were routinely prescribed after surgery, may shade the real effects of VTS on shoulder pain.
The limitations of this study are the retrospective nature and relatively small number of patients. However, to the best of our knowledge, this is the first study on PubMed to compare VTS and SID in laparoscopic bariatric surgery. Large-scale, randomized control trials are needed to demonstrate the impact of VTS on operative time and patient outcomes in laparoscopic bariatric surgery.
In conclusion, bradycardia during insufflation, operative time, blood loss, and complications, as well as shoulder pain were not significantly different between VTS and SID groups in this study. The VTS group showed a better surgeon’s satisfaction on the surgical field visualization than the SID group.