The present multicenter epidemiologic study demonstrated that complicating PI, such as strangulation or bowel necrosis, bowel obstruction, adynamic ileus, sepsis, shock, and massive gastrointestinal bleeding, was significantly associated with the small-bowel-involved combined type and the small-bowel-only type. A prospective multicenter study including 127 PI patients sponsored by the Association for Surgery of Trauma also revealed that the small bowel location of PI, peritonitis, and abnormal laboratory values such as an elevated international normalized ratio, decreased hemoglobin, and lactate values greater than 2.0 mmol/L were predictive of pathologic PI defined as the presence of transmural ischemia during surgical exploration or autopsy. A retrospective single-center study including 70 patients with PI or portal vein gas-clarified acute mesenteric ischemia was associated with small bowel PI, abdominal pain, elevated lactate, and the calculated vascular disease score. These studies are in line with the present finding, but in a retrospective single-center study including 97 patients with PI (46% colon, 27% stomach, 5% stomach, and 7% both small and large bowel), Morris et al reported that the location of pneumatosis alone was not predictive of outcome or intervention. The present study has the inherent limitation of its lack of data on blood and physical findings, but a comprehensive diagnosis that includes a physical examination with parameters such as vital and peritoneal signs, laboratory tests, and imaging modalities, is essential to rule out complicating PI. The association of the use of allopurinol/benzbromaron or hyperuricemia with PI remains unknown, but its association seems marginal with P-values of 0.0204.
This small-bowel-involved type was shown to be significantly associated with older age and chronic kidney disease in the present study. Among the four cases with chronic kidney disease, 3 were the small-bowel-only type while 1 was the large-bowel-only type, the difference of which seems marginal with P-values of 0.0468. There have been no reports regarding the association between affected segments of PI and kidney disease, but DuBose et al described that patients with pathologic type were more likely to be older, with a history of enteritis and chronic renal failure.
Regarding treatment, oxygen therapy was significantly associated with patients with a past medical history of bowel obstruction, and surgery was significantly associated with complicating PI. Hyperbaric oxygen therapy is a controversial treatment for adhesive postoperative small bowel obstruction, but Fukami et al described that 143 patients (87.7 %) were treated successfully with hyperbaric oxygen therapy without long-tube decompression. This oxygen therapy was associated with earlier resumption of oral intake and a shorter hospital stay, and the rate of operation was 7.4 % in the hyperbaric oxygen therapy group and 14.8 % in group treated by decompression alone. In this context, patients with PI with a history of bowel obstruction likely underwent oxygen therapy. Duron et al reported that abdominal distention, peritonitis, and lactic academia were predictive of positive intraoperative findings on multivariate analysis in a retrospective multicenter record review of 150 PI patients, 54 (36%) of whom were managed nonoperatively, 72 of whom underwent surgery, and 24 of whom were given comfort measures only. Generally, complicating or pathologic PI is an indication for surgery, as shown in the present study.
The last finding of the present study was that complicating PI was significantly associated with exacerbation of PI and subsequent death, which also makes medical sense. Wiesner et al reported that of seven patients with infarction limited to one bowel segment (jejunum, ileum, or colon), only one patient (14%) died, whereas of the 10 patients with infarction of two or three bowel segments, eight patients (80%) died. These authors concluded that CT findings of PI and portomesenteric venous gas due to bowel ischemia do not generally allow prediction of transmural bowel infarction because these findings may be observed in patients with only partial ischemic bowel wall damage, and the clinical outcomes of patients with bowel ischemia with these CT findings seem to depend mainly on the severity and extent of their underlying disease, which is consistent with our comprehensive finding.
The present study has inherent limitations, including its retrospective design, ethnically homogeneous sample, participation bias in terms of data collection, which was conducted mainly by gastroenterologists and a few surgeons but no radiologists or acute care physicians. Therefore, the proportion of surgery in the treatment was as low as 4.6%.