As in all surgery, first and foremost consideration is to the general condition of the patient and whether the overall health is such that the patient can tolerate the stress of anesthesia and major surgery. If a determination is made that the overall health is sufficiently good to tolerate anesthesia and major surgery, then for patients undergoing abdominal wall reconstruction for complex abdominal wall defects the next consideration would be about the possibility of developing IAH/ACS.

Morbid obesity is associated with a chronic form of IAH [7]. In such patients even minor elevations of IAP will rapidly lead to progression of the IAH to ACS. Pre-operative weight loss ameliorates the chronic IAH and thus reduces the risk of peri-operative IAH/ACS. Additionally, pre-operative weight loss, prior to complex abdominal wall reconstruction will improve the chances of a successful repair. As noted above, the earliest manifestations of IAH/ACS are on the respiratory and cardio-vascular systems, and hence the reserve available in those two organ systems determines the ability of the individual patient to tolerate IAH. In an otherwise healthy individual with relatively normal cardio-respiratory reserve, a 10% drop in venous return and/or ventilation is tolerated without significant ill effects. However, in patients with pre-existing cardiac/respiratory disease, even a <10% reduction may not be tolerated. Without performing detailed functional tests, it is not possible to quantify the state of the organ system or the reserve. However in most patients a judgment can be made as to whether after repair of the defect, the patient will have adequate ventilation. A detailed clinical examination with manual reduction of any hernia and manually “closing” the defect are crude clinical tests that can give a fair idea about the cardio-respiratory tolerance to the final repair. Additionally, a tight abdominal binder can be temporarily placed to reduce the hernia and the patient asked to walk around observing for any shortness of breath. If, based on these simple tests, it is determined the patient has adequate cardio-respiratory reserve , one can proceed with the surgery. If on the other hand, either the tests cannot be performed or after the clinical tests, it is felt that the patient has only borderline reserve, more objective testing with volumetric pulmonary function testing and/or stress tests should be considered. Each patient is truly unique and should be considered as such. It maybe helpful to communicate with the patient’s medical physicians to get as much information as possible before making a final decision about the patient’s ability to undergo repair without development of IAH/ACS.

Patients in whom a long standing large hernia has allowed the abdominal cavity proper to become so small that the herniated contents have lost their intra-abdominal domain, there is a high chance that the patient will develop IAH/ACS after reduction of contents and repair of defect. Even if the patient is able to tolerate the IAH and not develop ACS, the integrity of repair will be threatened unless proper planning is performed. Here too simple clinical tests outlined above allow for a determination to be made about the loss of domain. If there is doubt, computed tomographic (CT) measurements have been suggested that may aid in the determination [8]. However, CT can only perform static measurements of volume. The same available volume may suffice in a patient with laxity of muscle that allows for stretching, while that same volume may not be sufficient in another patient where the abdominal wall is scarred that does not allow stretching. Again a fair amount of judgment is necessary to adequately determine whether there is loss of domain. If there indeed is loss of domain, pre-operative tissue expansion techniques (e.g., pneumoperitoneum) maybe required to increase the overall volume of the abdominal cavity. In less severe cases, the choice of procedure (e.g., component separation) may need to be tailored to achieve a larger cavity and a more secure repair. These techniques are detailed in other chapters.

Even if the size of hernia is not very large and reduction of contents is tolerated well by the patient, it is possible that the defect in the musculo-aponeurotic layer is so large that when closed, will lead reduction in the volume of the abdominal cavity and IAH/ACS. After reduction of the hernia, in the clinic, the edges of the defect should be brought together manually and the patient observed for signs of respiratory embarrassment. If there is no respiratory embarrassment, it is safe to presume that after repair, ACS will not develop. If on the other hand, there is respiratory embarrassment, plans should be made accordingly for either pre-operative or intra-operative expansion of the abdominal cavity.