Abdominal compliance may influence intracranial pressure

We read with interest the recently published article by Kim et al., which speculates the relationship between obesity and optic nerve sheath diameter (ONSD) in patients undergoing laparoscopic gynecological surgery [1]. As the authors note, high abdominal pressure levels may further elevate intracranial pressure (ICP) during the steep Trendelenburg position and pneumoperitoneum. In the current article, Kim et al. stated they accepted patients with a history of ophthalmological, cerebrovascular, or brain tumor surgery as exclusion criteria. However, patients with a history of abdominal surgery or pulmonary diseases were not accepted as an exclusion criteria. This may complicate the results in this article somewhat. Understanding abdominal compliance (AC) is essential for grasping the efects of mentioned factors on abdominal pressure [2]. AC is defned as a change in abdominal volume per alteration of the intraabdominal pressure. Previous abdominal surgery may change abdominal compliance by gradually pre-stretching the abdominal muscles or decreasing the distensibility of the abdominal wall by scarring the muscle fbers and fascial layers [3]. On the other hand, these patients' compliance changes are observed less during surgery than in those without prior surgical experience [3]. Additionally, abdominal compliance (AC) is associated with not only altering the capacity of the abdominal wall but also with the stretching and pressurization capabilities of the diaphragm, which could be afected in individuals with chronic pulmonary lung disease [4]. This may impact ICP and ONSD by causing changes in thoracoabdominal pressure. Another noteworthy point in the article is that the cut-of value of body mass index (BMI) for classifying individuals as obese or non-obese is set at 30 kg/m2 . Therefore, the nonobese group also includes the data for overweight patients (BMI, 25 kg/m2 to 29.9 kg/m2 ). To clearly distinguish the impact of obesity on ONSD, it would be ideal to focus exclusively on individuals with a BMI above 30 kg/m2 for those classifed as obese and below 25 kg/m2 for those considered non-obese. This approach will efectively highlight the differences between these two groups [5]. This way, it can highlight the diferences between these two groups meaningfully. Based on the above, it may be more suitable to mention the surgical and pulmonary histories of patients. It would be more appropriate not to include overweight patients in the non-obese group to show the actual efect of obesity on ONSD during laparoscopic gynecological surgeries.