Chapter 14 Progressive Preoperative Pneumoperitoneum for Hernias with Loss of Abdominal Domain 
1 Clinical Anatomy
1 Features/Characteristics of the Defect
Definition of Loss of Abdominal Domain
There is no consensus in the literature on the definition of loss of abdominal domain. Determination of this condition is subjective and typically refers to massive hernias with a significant amount of intestinal contents that have herniated through the abdominal wall into a hernia sac that forms a secondary abdominal cavity. On physical exam, the inability to reduce the herniated contents below the level of the fascia when the patient is lying supine should raise suspicion of the diagnosis. Although the surgeon can often make the assumption that a patient has loss of domain on physical exam, we utilize computed tomography (CT) to determine the true nature of the hernia.2 Measuring Loss of Domain
We define a loss of abdominal domain on CT scan as greater than 50% of the intestinal contents lying outside the native abdominal cavity in the hernia sac. This may be more accurately defined when the ratio of the volume of the hernia sac to the volume of the abdominal cavity is ≥0.5.
A sagittal reconstruction of the CT scan is used to measure the length of the hernia sac from the top to the bottom of the sac. The length of the abdominal cavity is measured from the top of the diaphragm to the inferior aspect of the symphysis pubis (Fig. 14-1, A).
Axial reconstructions are used to measure the width of the hernia sac and abdominal cavity at their widest point. The height of the hernia sac is measured from an imaginary line drawn across the hernial orifice to the apex of the hernia sac at its tallest portion. The height of the abdominal cavity is measured from the anterior portion of the fourth lumbar space to an imaginary line drawn across the hernial orifice (see Fig. 14-1, B).
Physiology of Hernias with Loss of Abdominal Domain
In patients with loss of abdominal domain, the bowels reside outside the abdominal cavity. As intraabdominal pressure decreases to approach atmospheric pressure, abdominal viscera become edematous and their vasculature becomes engorged. This makes simple hernia reduction nearly impossible. In addition, respiratory function is altered secondary to the loss of diaphragmatic support, and anterior spinal support fails, leading to lordosis.4 Physiology of Progressive Preoperative Pneumoperitoneum
The immediate reintroduction of viscera and abdominal reconstruction in patients with loss of domain can result in a significant increase in intraabdominal pressure, which can lead to abdominal compartment syndrome and its resultant ill effects. Progressive preoperative pneumoperitoneum (PPP) attenuates the adverse physiologic effects associated with ventral hernia repair in patients with a loss of abdominal domain.
2 Preoperative Considerations
1 Physical Examination
The physical exam alone is often helpful in determining whether a patient has loss of domain. With the patient lying supine on the examination table, the surgeon should attempt to reduce the herniated contents below the fascia. If the hernia does not reduce because of the amount of herniated contents, the patient likely has loss of domain
2 Computed Axial Tomography
As previously described, the volume of the hernia sac and abdominal cavity are calculated and compared. A volume ratio of the hernia sac to the abdominal cavity of ≥0.5 should raise the suspicion of loss of abdominal domain.
