We thank Losanoff et al for their interest in recurrent ACS when a TAC has been used during a damage control procedure.1 In response to the authors' concerns about ongoing bleeding as an undiscovered cause of ACS, we submit the following: at reexploration for our patients with open abdomen ACS, the intra-abdominal findings were almost uniformly the same and no doubt the result of ongoing reperfusion injury. All patients had massively distended, thickened bowel walls with free serous fluid and no evidence of surgical bleeding. As previously reported,2,3 the technique of vacuum-pack open abdominal dressing is designed to drain free abdominal fluid from beneath the dressing via the negative pressure created from suction through the Jackson-Pratt drains. These lie between the intra-abdominal, nonadherent towel and the overlying Ioban drape (3M Health Care, St Paul, Minn). None of the patients in our series had expanding retroperitoneal hematomas or ongoing bleeding as the source of their open abdomen ACS. All suspicious retroperitoneal hematomas were explored and controlled either in the operating room during the original damage control procedure or postoperatively in the interventional radiology suite. The opacity of our temporary abdominal coverage does not preclude our ability to diagnose intra-abdominal complications such as bleeding, and enteral leakage can be assessed by the quantity and quality of the effluent from these drains. Last, with respect to the question of the vacuum pack's expansion capacity compared with other temporary abdominal closure systems, we offer the following observations. The average length and width of our open abdomen fascial defects are approximately 36 cm and 30 cm, respectively. The vertical height of the protuberant abdominal contents with the patient lying supine is routinely 8 cm above skin level. The outer Ioban drape is laid over this portion of the abdomen without any tension. This equates to roughly 1700 cm3 of additional abdominal cavitary capacity without exerting direct inward (medial) pull on the opened fascial walls. This system also maintains a clean intra-abdominal waterproof barrier and is durable enough to allow for prone position ventilation. No other temporary abdominal closure, to our knowledge, provides this amount of neoabdominal domain and versatility. Some new commercially available vacuum appliances market the ability to aid in fascial closure by exerting traction on fascial planes. This, in fact, prompted our study, because we feared that such dynamics might contribute to the development of intra-abdominal hypertension as viscera swelled during ongoing postoperative resuscitation. Despite the markedly enhanced survival rate of our damage-controlled open abdomen patients during the past decade,4 we continue to evaluate new strategies that might lessen the associated morbidity of this critical condition.