title: Impact of controlled intraabdominal pressure on the optic nerve sheath diameter during laparoscopic procedures.
abstract: BACKGROUND
  Acute elevations of intraabdominal pressure (IAP) are seen in many clinical scenarios with a consequent elevation in intracranial pressure (ICP). With the optic nerve sheath (ONS) being a part of the dura mater and the optic nerve surrounded by cerebral spinal fluid, a change in pressure within the subarachnoid space would be detected by ultrasonography, and invasive methods could be avoided. The study objective was to evaluate ultrasonographic modifications observed on the optic nerve sheath diameter during acute elevations of IAP in patients undergoing laparoscopic procedures.
  
  
  METHODS
  We prospectively collected data from patients who underwent laparoscopic procedures between July and August 2013. The optic nerve sheath diameter was measured sagittally with a 12-MHz transducer. The measurements were obtained at baseline, 15 and 30 min, and at the end of surgery.
  
  
  RESULTS
  There were 16 females (36.4%) and 28 males (63.6%), with a mean age of 44.22 ± 10.44 years (range 23-66) and body mass index of 29.45 ± 6.53 kg/m(2) (range 21-39). The mean optic nerve sheath diameter was 4.8 ± 1.0 mm at baseline, 5.5 ± 1.1 mm at 15 min, 5.9 ± 1.0 mm at 30 min, and 5.1 ± 1.2 mm after deflation of pneumoperitoneum. The diameter increased significantly at 15 min by a median of 0.6 mm (interquartile range 0.3, 0.8; p < 0.0001) and at 30 min by a median of 1.0 mm (interquartile range 0.7, 1.4; p < 0.0001), returning close to baseline after surgery.
  
  
  CONCLUSIONS
  The acute elevation in IAP during laparoscopy significantly increased the optic nerve sheath diameter. The changes in the ONSD reflect a temporary and reversible increase in the ICP due to the acute elevation of IAP.
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: Fernando
authors.initials: F
authors.lastname: Dip
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: David
authors.initials: D
authors.lastname: Nguyen
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: Armando
authors.initials: A
authors.lastname: Rosales
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: Morris
authors.initials: M
authors.lastname: Sasson
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Lo Menzo
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA.
authors.forename: Samuel
authors.initials: S
authors.lastname: Szomstein
authors.affiliation: The Bariatric and Metabolic Institute and Section of Minimally Invasive Surgery, Department of General Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd., Weston, FL, 33331, USA. rosentr@ccf.org.
authors.forename: Raul
authors.initials: R
authors.lastname: Rosenthal
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects*; D011446:Prospective Studies; D014463:Ultrasonography
keywords: Intracranial pressure; Laparoscopy; Minimally invasive surgery; Optic sheath nerve diameter