Ischemic colitis as a cause of massive lower gastrointestinal bleeding and peritonitis. Report of five cases

Intraoperative fluorescence perfusion assessment should be corrected by a measured subject-specific arterial input function

SIGNIFICANCE

The effects of varying the indocyanine green injection dose, injection rate, physiologic dispersion of dye, and intravenous tubing volume propagate into the shape and magnitude of the arterial input function (AIF) during intraoperative fluorescence perfusion assessment, thereby altering the observed kinetics of the fluorescence images in vivo.

AIM

Numerical simulations are used to demonstrate the effect of AIF on metrics derived from tissue concentration curves such as peak fluorescence, time-to-peak (TTP), and egress slope.

APPROACH

Forward models of tissue concentration were produced by convolving simulated AIFs with the adiabatic approximation to the tissue homogeneity model using input parameters representing six different tissue examples (normal brain, glioma, normal skin, ischemic skin, normal bone, and osteonecrosis).

RESULTS

The results show that AIF perturbations result in variations in estimates of total intensity of up to 80% and TTP error of up to 200%, with the errors more dominant in brain, less in skin, and less in bone. Interestingly, error in ingress slope was as high as 60% across all tissue types. These are key observable parameters used in fluorescence imaging either implicitly by viewing the image or explicitly through intensity fitting algorithms. Correcting by deconvolving the image with a measured subject-specific AIF provides an intuitive means of visualizing the data while also removing the source of variance and allowing intra- and intersubject comparisons.

CONCLUSIONS

These results suggest that intraoperative fluorescence perfusion assessment should be corrected by patient-specific AIFs measured by pulse dye densitometry.

An intelligent electronic capsule system for automated detection of gastrointestinal bleeding

In clinical practice, examination of the hemorrhagic spot (HS) remains difficult. In this paper, we describe a remote controlled capsule (RCC) micro-system with an automated, color-based sensor to identify and localize the HS of the gastrointestinal (GI) tract. In vitro testing of the detecting sensor demonstrated that it was capable of discriminating mimetic intestinal fluid (MIF) with and without the hemoglobin (Hb) when the concentration of Hb in MIF was above 0.05 g/ml. Therefore, this RCC system is able to detect the relatively accurate location of the HS in the GI tract.

Intestinal (mesenteric) vasculopathy. I. Acute superior mesenteric arteriopathy and venopathy

Intestinal vasculopathy is not rare, comprising about 1 per 1000 hospital admissions. Primary mesenteric vasculopathy causes cardiovascular disease, whereas secondary mesenteric ischemia causes extrinsic vascular compression or vascular trauma. Acute superior mesenteric arteriopathy is caused by a mesenteric embolus, thrombus, or vasospasm (i.e., nonocclusive vasculopathy). Acute superior mesenteric venopathy is caused by a thrombus, which is often associated with a hypercoagulopathy. The clinical presentation of both diseases is often subtle and nonspecific at an early stage and becomes overt and specific only when advanced and severe, when ischemia progresses to necrosis. The mortality of acute superior mesenteric arteriopathy is still very high, whereas superior mesenteric venopathy is less rapidly progressive and has a lower, but still significant, mortality. Early diagnosis and aggressive therapy significantly reduces the mortality of these life-threatening diseases.

Intestinal (mesenteric) vasculopathy. II. Ischemic colitis and chronic mesenteric ischemia

Ischemic colitis accounts for approximately half of all cases of mesenteric vasculopathy. The clinical presentation varies depending on underlying cause, extent of vascular obstruction, rapidity of ischemic insult, degree of collateral circulation, and presence of comorbidity. Ischemic colitis is usually diagnosed by colonoscopy. Only approximately 20% of patients require surgery because of signs or laboratory findings of peritonitis or because of clinical deterioration. Approximately 20% of patients develop chronic colitis from irreversible colonic ischemic injury, which manifests clinically as persistent diarrhea, rectal bleeding, or weight loss and endoscopically as a colonic stricture or mass. Chronic mesenteric ischemia is almost always caused by significant atherosclerotic stenosis involving at least two mesenteric arteries, usually the superior mesenteric artery and celiac axis. The classic symptomatic triad of postprandial pain, fear of eating, and involuntary weight loss occurs with advanced disease.

Ischemic colitis

Colon ischemia is a well-recognized clinical entity that often occurs spontaneously in patients over the age of 50 years. Many previous cases of nonspecific colitis are now felt to have been secondary to an ischemic event. In contrast to patients with acute mesenteric ischemia and extensive necrosis of the small bowel, the majority of patients with isolated colon ischemia follow a benign clinical course. Most patients present days, weeks, or months after the initial ischemic insult, and many may not have any recognizable antecedent episode of colon ischemia. However, some patients develop a fulminant form of the disease that causes colon infarction and death if not treated early. A high index of suspicion is necessary to make the diagnosis in the hospitalized patient. Endoscopy is recommended to confirm the diagnosis and the extent of injury and to monitor progression or resolution of disease. Aggressive management is of paramount importance to minimize the damage to the ischemic colon and reduce the otherwise high in-hospital mortality rate. Surgical intervention is indicated for patients with evidence of peritonitis or transmural infarction or perforation of the colon and for patients with chronic symptomatic colitis or stricture.

The causes and management of lower GI bleeding: a study based on clinical observations at Hanyang University Hospital

During the period of the study, lower GI bleeding patients comprised a constant 1.6% of the total admitted patients at Hanyang University Hospital annually. There were no statistically significant changes according to year. The 970 cases were classified as follows: hemorrhoid and anal fissure 65.5%, malignant neoplasm 21.1% (rectal cancer 16.9%, sigmoid colon cancer 3.3%, anal cancer 0.9%), benign neoplasm 4.2%, ulcerative colitis 3.3%, infectious colitis 2.3%, ischemic colitis 1.8%, radiation colitis 1.3%, diverticulosis 0.3%, and others 0.2%. Ulcerative colitis and rectosigmoid cancer showed increasing trends, while other disease groups showed no change in the occurrence rate. Hemorrhoid and anal fissure developed mostly in the 30s age group, benign polyp and ulcerative colitis in the 40s age group, malignant neoplasm in the 50s age group, and ischemic colitis and radiation colitis in the 60s age group. There was no sexual predominance of lower GI bleeding. About 10% of the patients admitted to the hospital needed transfusions, particularly patients with ulcerative colitis (21.9%) and radiation colitis (23.1%). 20.2% of the patients improved with supportive measures and medical treatment and 79.8% underwent surgical operation. In particular, 51.2% of the patients with benign neoplasm underwent polypectomies.