Traumatic diaphragmatic injuries

Conclusions: These results suggest, for the first time, that tissue-engineered intestine develops a mature immune system in response to luminal antigenic stimuli. Our neointestine may be suitable for clinical application in patients suffering from short bowel syndrome. 15 Traumatic diaphragmatic injuries Alsoufi B, Islam S, Lancey RW. From the University of Massachusetts Medical School, Worcester, Massachusetts. Purpose: Traumatic injuries to the diaphragm have been increasing, mainly because of increased road traffic accidents and violence. The diagnosis of this injury poses a challenge to the surgeon and is frequently missed or delayed. We try in this study to identify the mode of presentation and the associated injuries, complications, and factors affecting the morbidity and mortality. In addition we evaluate the efficacy of the different diagnostic tests to identify these patients. Methods: A retrospective review of all trauma admissions from 1989 to 2001 was performed, and cases of diaphragmatic injury were identified. Trauma information, demographics, and outcome data were compiled and analyzed. Results: A total of 85 patients were identified during the study period, 54 males and 31 females, with 58 patients (68%) having blunt trauma and 27 (32%) having penetrating stab wounds (18) and GSW (9). The left hemidiaphragm was involved in about 76% of cases and the right side in 21 cases. In three blunt traumas, bilateral involvement was included. Signs and symptoms varied according to the associated injuries that were present in all patients. Most common injuries were in the spleen (55%), liver (43%), stomach, colon, and mesentery (14%) each; also, pneumothorax was present in 42% of patients and hemothorax in 48%. Aortic and cardiac injuries were present in 6% and 7% respectively. Other injuries included pelvic Fx (21%), upper and lower extremities Fx (33%), rib Fx 48%, spinal injury (31%), and CHI (46%). One-third of the patients had displacement of abdominal contents to the chest, with the stomach, colon, and spleen being the most common organs to herniated, respectively. CXR was the most helpful study; however, it was normal in 34% of patients. DPL was performed in 26 patients and was positive in 19. Computed tomography scan was able to detect the injury in 9 patients. Fifty-eight patients required laparotomy alone, 3 laparoscopy, 20 laparotomy and thoracotomy, and 4 were repaired by thoracotomy alone. Mortality was 24 patients (41%), with almost half of those secondary to intractable bleeding. Complications occurred in 26 patients (31%) and were most commonly pulmonary. Patients with higher ISS and GCS had more incidence of complications and longer intensive care stay and ventilator requirements. Conclusions: Diaphragmatic injury is not uncommon or easy to diagnose, and it should be suspected in all patients with blunt or penetrating injury to the thoracoabdominal trunk; otherwise, it can be missed. Radiographic assessment is not adequate in ruling out the injury. Associated injuries are common and are the determining factors for morbidity, mortality, and length of stay. Most cases can be managed by laparotomy, with laparoscopy possible in stable cases. 16 Type II error in randomized controlled trials with negative results—are methods improving? Orseck M, Johnson J, Orr R. From the Department of Medical Education (Surgery), Spartanburg Regional Medical Center, Spartanburg, South Carolina. Purpose: In 1994, Moher and colleagues (JAMA 272:122-124) noted that most published randomized controlled trials (RCTs) with negative results did not have enough statistical power to detect 25% or 50% relative differences between trial groups, and they proposed a more standardized reporting of sample size and power calculations. The objective of this study is to describe the pattern of reporting in recently published RCTs with special attention to statistical power and appropriate sample size.

Methods: A total of 30 consecutive negative RCTs were analyzed: 10 from prestigious multispecialty journals (JAMA, NEJM), 10 from internal medicine journals (Ann Int Med, Arch Int Med), and 10 from surgical journals (Surgery, Arch Surg). All analyzed articles were published from 1998 to 2000. For each trial, we recorded the presence or absence of an explicit power analysis, and we calculated each study’s ability to detect 25% or 50% relative differences between study groups. (Power calculations were not possible for 23% of the included series because of lack of information in the article.) Results: Power calculations were formally stated in 43% of RCTs surveyed (60% for JAMA/NEJM, 50% for medical, but only 20% for surgical). A total of 52% of the RCTs had enough statistical power (80%) to detect a 50% difference between groups, but only 30% had enough statistical power to detect a 25% difference between groups. Several studies had fewer than 10% of the subjects required to exclude a 50% difference between groups. In many cases (especially in the 2 surgical journals), RCTs with grossly inappropriate sample sizes presented data contrary to the “accepted” literature, advising physicians to change their usual practices. Conclusions: This analysis highlights the continued problem with type II statistical error. These results are consistent with data published in 1994, which show minimal improvement in the interval. Results are particularly poor in the 2 sampled surgical journals. Journal editors (and readers) must be made aware of the potential pitfalls of drawing conclusions from studies subject to type II error.

17 Use of cryopreserved cadaver vein allograft for hemodialysis precludes renal transplantation due to allosensitization Benedetto B,* Lipkowitz G,* Madden R,* Kurbanov A,* Hull D.† From the *Department of Surgery, Transplant Division, Baystate Medical Center, Tufts University School of Medicine, Springfield, Massachusetts and the †Department of Surgery, Transplant Division, Hartford Hospital, University of Connecticut Medical Center, Farmington, Connecticut. Purpose: Dimethyl sulfoxide (DMSO) cryopreserved cadaver vein allografts have recently been proposed as an alternative to prosthetic grafts in the problem hemodialysis population. The transfer of mismatched major histocompatibility complex (MHC) I and MHC II molecules in association with these allografts can potentially lead to allosensitization in nonimmunosuppressed individuals. Setting: University affiliated medical center. Design: Retrospective. Patients: Twenty consecutive patients receiving technically successful upper arm cadaver vein allograft fistulae (CAVF) for hemodialysis between April 1999 and April 2000. A control cohort of 20 renal transplant waiting list patients was selected by transplant nurses blinded to the study. These patients were matched for age, sex, history of transfusion, pregnancy, cause of renal failure, and prior transplantation. PRA values were recorded in this group over the same time period as in the CAVF group. Results: Patients receiving CAVF had a mean panel reactive antibody (PRA) assay value of 84.1% (median, 96.5%) at an average of 3.1 months postengraftment (median, 1.5 months). Pre-engraftment PRA values were available for 7 patients who were on the transplant waiting list. Six of these patients had nonreactive PRA assays before CAVF creation. All of these patients converted to positive PRA assays after CAVF creation, with a mean value of 92.3% (median, 98%) at 2.85 months follow-up (median, 1.3 months). The mean PRA value for the control cohort was 5.5% (median, 2.5%), with no patients converting from a nonreactive to a reactive PRA assay during this same time interval. Conclusions: The use of DMSO cryopreserved cadaver vein allografts for hemodialysis access leads to broad allosensitization as measured by PRA assay. Cryopreserved cadaver vein allografts should not be used for hemodialysis access in potential renal transplant recipients.

CURRENT SURGERY • Volume 58/Number 6 • November/December 2001

561