Suitable patients for single-port laparoscopic adrenalectomy: optimal cut-off value of body mass index
Recently, the single-port approach has attracted attention with evolution to less invasive surgery, but it is considered that single-port surgery should be performed by experienced surgeons because of the difficulties. In this study, we tried to identify the patients who were suitable for single-port laparoscopic adrenalectomy, focusing on the optimal cut-off values of the body mass index (BMI) and the visceral fat area / total fat area (VFA/TFA) ratio. It is hoped that the results will be useful for making decisions about the surgical approach to adrenal tumors.
A retrospective study was conducted in 126 consecutive patients who underwent single-port adrenalectomy between 2009 and 2015. All operations were done via the transperitoneal approach, after a single access port (SILS port) was placed at the umbilicus with a 2.5 cm skin incision. For right adrenalectomy, an additional 2-mm port was used for liver retraction. We used a 5 mm flexible camera, as well as flexible devices (SILS clinch and SILS hook) and energy devices (Enseel or Ligasure). TFA and VFA were measured at the L4 level on preoperative CT scans. The pneumoperitoneum time (PT) was employed as an objective index for the assessment of surgical difficulty.
Figure 1 is a bar graph of the mean PT for each BMI range, demonstrating that the cut-off value for BMI is 24 kg/m2. In 80 patients with a BMI less than 24 kg/m2, PT was significantly shorter than in those whose BMI exceeded 24 kg/m2 (78 vs. 94 minutes, p=0.038). Mean PT was 71 minutes in 27 patients with a BMI less than 20 kg/m2, while mean PT was 134 minutes in 9 patients with a BMI exceeding 28 kg/m2. Figure 2 shows the mean PT in each range of the VFA/TFA ratio, demonstrating a clear cut-off value of 0.4 for this ratio. PT was shorter in 65 cases with a VFA/TFA ratio less than 0.4 than in those with a ratio exceeding 0.4 (78 vs. 91 minutes, p=0.056).
BMI is associated with the PT for single-port laparoscopic adrenalectomy, and the optimal cut-off value is 24 kg/m2. Patients with a BMI less than 20 kg/m2 are thought to be suitable for novice surgeons. Conversely, even experienced surgeons should carefully consider performing single-port surgery in patients whose BMI exceeds 28 kg/m2. The VFA/TFA ratio was also a predictor of the technical difficulty of single-port surgery, and its optimal cut-off value was 0.4.