title: Relationship between ventral hernia defect area and intra-abdominal pressure: dynamic in vivo measurement.
abstract: BACKGROUND
  It is an acceptable concept that the ventral hernia defect area will increase with a rise in intra-abdominal pressure (IAP). The literature lacks the evidence about how much this increase is in vivo. The aim of this study was to objectively measure the change in the ventral hernia defect area with increasing intra-abdominal pressure.
  
  
  METHODS
  In a prospective study of laparoscopic ventral hernia repair, the area of hernia defect was measured from inside the abdomen using a sterile paper ruler. The horizontal (width) and vertical (length) measurements of the defect were taken at two pressure points: (IAP = 8 mmHg) and (IAP = 15 mmHg). The hernia defect area was calculated as an oval shape using a standard formula.
  
  
  RESULTS
  Eighteen consecutive patients with a ventral hernia were included in this study (8 males: 10 females). Median age was 60 years (30-81), body mass index (BMI) was 29.9 (22.6-37.6). Changing the IAP significantly, (P < 0.001) changed the values of horizontal and vertical measurements, and the calculated area of the ventral hernia defect. The median calculated defect area, as an oval shape, was 5.6 cm(2) (Q1-Q3 = 3.5-15.5) and 6.9 cm(2) (Q1-Q3 = 4.5-18.7) at 8 and 15 mmHg IAP, respectively. The calculated area of mesh required to cover the defect with a 5 cm overlap increased by a median of 5% (Q1-Q3 = 3-6%). The change in defect area did not differ significantly between obese and non-obese patients (P = 0.5).
  
  
  CONCLUSIONS
  Dynamic, rather than static, measurements of ventral hernia area during laparoscopy provide a simple way of in vivo objective measurement that helps the surgeon choose the appropriate area of mesh. When choosing mesh area, we support the trend toward a larger overlap of at least 5 cm if less precise methods of measuring defect area are been used.
authors.affiliation: Department of Surgery, School of Medicine, University of Glasgow, Glasgow, G12 8QQ, UK. hgbqandeel@yahoo.com.
authors.forename: Haitham
authors.initials: H
authors.lastname: Qandeel
authors.affiliation: Department of Surgery, School of Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: O'Dwyer
mesh_terms: D034841:Abdominal Cavity / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006555:Hernia, Ventral / Q000601:surgery*; D059685:Herniorrhaphy / Q000379:methods*; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D011312:Pressure; D011446:Prospective Studies; D013526:Surgical Mesh
keywords: Defect area; Hernia; Intra-abdominal pressure