Authors: Cetin E et al.
BMC Anesthesiology, 2026
This prospective, randomized, observer-blinded clinical trial examined how low-pressure (8 mmHg) versus high-pressure (14 mmHg) pneumoperitoneum affects optic nerve sheath diameter (ONSD)—a surrogate marker for intracranial pressure—during laparoscopic cholecystectomy.
Laparoscopic surgery with pneumoperitoneum is known to increase intra-abdominal pressure, which can impact venous return, cerebral venous drainage, and potentially intracranial pressure. ONSD measured by ultrasound has emerged as a practical, noninvasive way to track these changes in real time.
In this study of 76 ASA I–II patients, ONSD was measured at multiple time points from baseline through the intraoperative period and into early recovery. Both groups experienced increases in ONSD after pneumoperitoneum was initiated, confirming that even standard laparoscopic pressures influence intracranial dynamics.
However, the magnitude of change differed significantly. Patients in the high-pressure group (14 mmHg) had greater and more pronounced increases in ONSD, particularly early after insufflation. This suggests a higher transient rise in intracranial pressure compared to the low-pressure group (8 mmHg).
Importantly, these changes were not permanent. By the second postoperative hour, ONSD values in both groups had returned close to baseline, indicating that the effect is reversible in otherwise healthy patients.
Clinical outcomes also differed. The high-pressure group experienced significantly higher rates of postoperative nausea, vomiting, and headache. These symptoms may reflect transient intracranial pressure changes, altered cerebral venous drainage, or other physiologic effects of higher insufflation pressures.
The findings reinforce the physiologic trade-offs of pneumoperitoneum. While higher pressures may improve surgical exposure, they come at the cost of greater systemic and cerebral physiologic disturbance.
Limitations include the relatively healthy study population, which may underestimate effects in higher-risk patients such as those with neurologic disease, obesity, or impaired cerebral compliance. Additionally, ONSD is an indirect measure of intracranial pressure and may not capture all aspects of intracranial physiology.
Key Points
- Pneumoperitoneum increases optic nerve sheath diameter in all patients
- High-pressure (14 mmHg) causes significantly greater increases than low-pressure (8 mmHg)
- Changes are transient and return toward baseline postoperatively
- Higher pressure associated with increased postoperative nausea, vomiting, and headache
- ONSD ultrasound provides a useful noninvasive marker of intracranial dynamics
What You Should Know
This study adds to the growing argument for using the lowest effective insufflation pressure during laparoscopy. The difference is not just theoretical—higher pressures measurably affect intracranial physiology and patient symptoms. In routine cases, especially in healthier patients, these effects are transient. But in patients with limited intracranial compliance or other risk factors, this could matter more. If the surgeon can work at lower pressures, it is likely the safer physiologic choice.
We want to thank BMC Anesthesiology for allowing us to summarize and share this important work with the anesthesia community.