Use of visible light spectroscopy to diagnose chronic gastrointestinal ischemia and predict response to treatment.

BACKGROUND & AIMS: Chronic gastrointestinal ischemia (CGI) is more common than previously thought. Visible light spectroscopy (VLS) allows for noninvasive measurements of mucosal capillary hemoglobin oxygen saturation during endoscopy. We evaluated the response of patients with occlusive CGI to treatment after evaluation by radiologic imaging of the vasculature and VLS. We also identified factors associated with response to treatment in these patients. METHODS: In a prospective study, we collected data from 212 patients referred for evaluation of suspected CGI from November 2008 through January 2011. Patients underwent an extensive evaluation that included visualization of gastrointestinal arteries and assessments of mucosal perfusion by means of VLS. Treatment response was evaluated in patients with occlusive CGI. Factors associated with response to therapy were assessed by using multivariate logistic regression analysis. RESULTS: Occlusive CGI was diagnosed in 107 patients (50%); 96 were offered treatment (90%). After median follow-up period of 13 months, data on treatment response were available from 89 patients (93%); 62 patients had a sustained response (70%). Weight loss before treatment (odds ratio [OR], 1.93), presence of an abdominal bruit (OR, 2.36), and corpus mucosal saturation level <56% (OR, 4.84) were the strongest predictors of a positive response to treatment. CONCLUSIONS: Treatment of CGI, diagnosed by a multimodal approach, provides a substantial long-term rate of response (70% in 13 months). Weight loss, abdominal bruit, and low corpus mucosal saturation identify patients most likely to respond to treatment. Multiple techniques should therefore be used to assess patients with CGI, including VLS measurements, to detect mucosal hypoxia.

Patients with chronic gastrointestinal ischemia have a higher cardiovascular disease risk and mortality.

OBJECTIVES: We determined the prevalence of classical risk factors for atherosclerosis and mortality risk in patients with CGI. METHODS: A case-control study was conducted. Patients referred with suspected CGI underwent a standard work-up including risk factors for atherosclerosis, radiological imaging of abdominal vessels and tonometry. Cases were patients with confirmed atherosclerotic CGI. Controls were healthy subjects previously not known with CGI. The mortality risk was calculated as standardized mortality ratio derived from observed mortality, and was estimated with ten-year risk of death using SCORE and PREDICT. RESULTS: Between 2006 and 2009, 195 patients were evaluated for suspected CGI. After a median follow-up of 19 months, atherosclerotic CGI was diagnosed in 68 patients. Controls consisted of 132 subjects. Female gender, diabetes, hypercholesterolemia, a personal and family history of cardiovascular disease (CVD), and current smoking are highly associated with CGI. After adjustment, female gender (OR 2.14 95% CI 1.05-4.36), diabetes (OR 5.59, 95% CI 1.95-16.01), current smoking (OR 5.78, 95% CI 2.27-14.72), and history of CVD (OR 21.61, 95% CI 8.40-55.55) remained significant. CGI patients >55 years had a higher median ten-year risk of death (15% vs. 5%, P = 0.001) compared to controls. During follow-up of 116 person-years, standardized mortality rate was higher in CGI patients (3.55; 95% CI 1.70-6.52). CONCLUSIONS: Patients with atherosclerotic CGI have an increased estimated CVD risk, and severe excess mortality. Secondary cardiovascular prevention therapy should be advocated in patients with CGI.

Small bowel Crohn's disease: MR enteroclysis and capsule endoscopy compared to balloon-assisted enteroscopy.

New modalities are available to visualize the small bowel in patients with Crohn's disease (CD). The aim of this study was to compare the diagnostic yield of magnetic resonance enteroclysis (MRE) and capsule endoscopy (CE) to balloon-assisted enteroscopy (BAE) in patients with suspected or established CD of the small bowel. Consecutive, consenting patients first underwent MRE followed by CE and BAE. Patients with high-grade stenosis at MRE did not undergo CE. Reference standard for small bowel CD activity was a combination of BAE and an expert panel consensus diagnosis. Analysis included 38 patients, 27 (71%) females, mean age 36 (20-74) years, with suspected (n = 20) or established (n = 18) small bowel CD: 16 (42%) were diagnosed with active CD, and 13 (34%) by MRE with suspected high-grade stenosis, who consequently did not undergo CE. The reference standard defined high-grade stenosis in 10 (26%) patients. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value of MRE and CE for small bowel CD activity were 73 and 57%, 90 and 89%, 88 and 67%, and 78 and 84%, respectively. CE was complicated by capsule retention in one patient. MRE has a higher sensitivity and PPV than CE in small bowel CD. The use of CE is considerably limited by the high prevalence of stenotic lesions in these patients.

Single-balloon enteroscopy, magnetic resonance enterography, and abdominal US useful for evaluation of small-bowel disease in children with (suspected) Crohn's disease.

BACKGROUND: The usefulness of single-balloon enteroscopy (SBE) has not been evaluated in children with known or suspected Crohn's disease (CD). OBJECTIVE: The objectives of this study are to evaluate the diagnostic yield of SBE for pediatric CD by comparing it with US and magnetic resonance enterography (MRE). DESIGN: Single-center prospective study. SETTING: Tertiary-care referral hospital. PATIENTS: Between February 2009 and April 2010, 20 pediatric patients (ages 8-18 years) with suspected inflammatory bowel disease (IBD) or with a previous diagnosis of CD with suspected persistent small-bowel disease were enrolled. INTERVENTIONS: All patients underwent proximal and distal SBE, 17 patients also underwent US combined with Doppler flow measurements, and 18 underwent MRE. MAIN OUTCOME MEASUREMENTS: The findings of US with Doppler flow measurements and MRE were compared with those with SBE. RESULTS: The mean patient age was 15.0 years (range 11.3-18 years, 70% male). Of 14 patients with suspected IBD, 8 had a diagnosis of CD made after SBE. Activity in the small bowel was found in 14 patients (70%) with both suspected and previously diagnosed CD. Twelve patients (60%) had small-bowel disease that was out of reach of conventional endoscopy. Three patients (15%) had small-bowel activity solely in the jejunum, which was not detected by either MRE or US. LIMITATIONS: Single-center study with small sample size. CONCLUSIONS: SBE can be used in children to accurately assess small-bowel disease and CD. Small-bowel activity may be identified by SBE in some patients in whom it may not be apparent despite use of conventional upper endoscopy, ileocolonoscopy, US with Doppler flow measurements, or MRE.

Double balloon enteroscopy and capsule endoscopy for obscure gastrointestinal bleeding: an updated meta-analysis.

BACKGROUND AND AIM: Uncertainty remains about the best test to evaluate patients with obscure gastrointestinal bleeding (OGIB). Previous meta-analyses demonstrated similar diagnostic yields with capsule endoscopy (CE) and double balloon enteroscopy (DBE) but relied primarily on data from abstracts and were not limited to bleeding patients. Many studies have since been published. Therefore, we performed a new meta-analysis comparing CE and DBE focused specifically on OGIB. METHODS: A comprehensive literature search was performed of comparative studies using both CE and DBE in patients with OGIB. Data were extracted and analyzed to determine the weighted pooled diagnostic yields of each method and the odds ratio for the successful localization of a bleeding source. RESULTS: Ten eligible studies were identified. The pooled diagnostic yield for CE was 62% (95% confidence interval [CI] 47.3-76.1) and for DBE was 56% (95% CI 48.9-62.1), with an odds ratio for CE compared with DBE of 1.39 (95% CI 0.88-2.20; P = 0.16). Subgroup analysis demonstrated the yield for DBE performed after a previously positive CE was 75.0% (95% CI 60.1-90.0), with the odds ratio for successful diagnosis with DBE after a positive CE compared with DBE in all patients of 1.79 (95% CI 1.09-2.96; P = 0.02). In contrast, the yield for DBE after a previously negative CE was only 27.5% (95% CI 16.7-37.8). CONCLUSIONS: Capsule endoscopy and double balloon enteroscopy provide similar diagnostic yields in patients with OGIB. However, the diagnostic yield of DBE is significantly higher when performed in patients with a positive CE.

Endoscopic visible light spectroscopy: a new, minimally invasive technique to diagnose chronic GI ischemia.

BACKGROUND: The diagnosis of chronic GI ischemia (CGI) remains a clinical challenge. Currently, there is no single simple test with high sensitivity available. Visible light spectroscopy (VLS) is a new technique that noninvasively measures mucosal oxygen saturation during endoscopy. OBJECTIVE: To determine the diagnostic accuracy of VLS for the detection of ischemia in a large cohort of patients. DESIGN: Prospective study, with adherence to the Standards for Reporting of Diagnostic Accuracy. SETTING: Tertiary referral center. PATIENTS: Consecutive patients referred for evaluation of possible CGI. INTERVENTIONS: Patients underwent VLS along with the standard workup consisting of evaluation of symptoms, GI tonometry, and abdominal CT or magnetic resonance angiography. MAIN OUTCOME MEASUREMENTS: VLS measurements and the diagnosis of CGI as established with the standard workup. RESULTS: In 16 months, 121 patients were included: 80 in a training data set and 41 patients in a validation data set. CGI was diagnosed in 89 patients (74%). VLS cutoff values were determined based on the diagnosis of CGI and applied in the validation data set, and the results were compared with the criterion standard, resulting in a sensitivity and specificity of VLS of 90% and 60%, respectively. Repeated VLS measurements showed improvement in 80% of CGI patients after successful treatment. LIMITATIONS: Single-center study; only 43% of patients had repeated VLS measurements after treatment. CONCLUSIONS: VLS during upper endoscopy is a promising easy-to-perform and minimally invasive technique to detect mucosal hypoxemia in patients clinically suspected of having CGI, showing excellent correlation with the established ischemia workup.

Radiological imaging and gastrointestinal tonometry add value in diagnosis of chronic gastrointestinal ischemia.

BACKGROUND & AIMS: The diagnosis of chronic gastrointestinal ischemia (CGI) remains a clinical challenge. We aimed to assess the diagnostic value of clinical features, visualization of the gastrointestinal arteries, and evaluation of mucosal perfusion in patients clinically suspected of CGI. METHODS: A total of 186 patients referred for suspicion of CGI were prospectively included and followed up. All patients had an extensive diagnostic work-up, including visualization of the gastrointestinal arteries with computed tomography, magnetic resonance, or conventional angiography, and mucosal perfusion with tonometry. The reference standard for CGI was persistent clinical response after adequate therapy. The diagnostic value of individual and combined tests was assessed with multivariable logistic regression analysis. RESULTS: A total of 116 (62%) patients were diagnosed with CGI. In a multivariable model solely based on clinical features, the strongest predictors for CGI were the presence of postprandial pain, weight loss per month in kilograms, concomitant cardiovascular disease, and presence of an abdominal bruit. However, this model showed limited discriminative ability for the presence or absence of CGI (c-statistic, 0.62). Adding radiologic imaging to the prediction model improved the discriminative ability substantially (c-statistic, 0.81). Adding tonometry to the prediction model further improved the discriminative ability of the model (c-statistic, 0.90). The combination of clinical features and tonometry with a c-statistic of 0.88 approximated the discriminative ability of the latter model. CONCLUSIONS: Clinical features alone have a limited value to assess CGI correctly. Visualization of the gastrointestinal arteries and evaluation of mucosal perfusion substantially improve the diagnosis of CGI. The strongest diagnostic contribution comes from mucosal perfusion assessment.

Chronic gastrointestinal ischaemia: shifting paradigms.

Chronic gastrointestinal ischaemia (CGI) is generally considered to be a rare disease entity. The majority of patients with CGI are only diagnosed after a long period of slowly progressive abdominal symptoms, in some cases with impressive weight loss. These patients may have a broad range of clinical signs and quite often undergo repeated extensive evaluation of their symptoms with negative outcome. The classical triad of symptoms, also known as 'abdominal angina', is defined as the combination of postprandial pain, weight loss due to fear of pain after eating, and an abdominal bruit during physical examination. Recent studies have shed new lights on these long unchallenged concepts. These studies first showed that CGI is more prevalent than previously thought and can occur in patients with both single- and multi-vessel disease. Second, the disease presents with a much wider range in symptoms, and only a minority of patients present with the classical triad. Third, long-term positive outcomes can be achieved after endovascular or surgical revascularisation therapy in large proportion of patients. This knowledge results from a combination of clinical research by dedicated focus groups, the current widespread availability of new imaging techniques such as CT-angiography, the development of new functional tests for assessment of mucosal perfusion, and the evolution of endovascular stenting options. Clinicians diagnosing and treating patients with acute and chronic abdominal conditions have to be aware of these new developments. We therefore here review the new insights on CGI with a focus on epidemiology, pathophysiology, current diagnostics and treatment.

Serum markers and intestinal mucosal injury in chronic gastrointestinal ischemia.

BACKGROUND: Diagnosing chronic gastrointestinal ischemia (CGI) is a challenging problem in clinical practice. Serum markers for CGI would be of great diagnostic value as a non-invasive test method. AIMS: This study investigated serum markers in patients with well-defined ischemia. Furthermore, intestinal mucosal injury was also evaluated in CGI patients. METHODS: Consecutive patients suspected of CGI were prospectively enrolled and underwent a diagnostic work-up consisting of gastrointestinal tonometry and either CT or MR angiography. Blood samples for analysis of intestinal fatty acid-binding protein (I-FABP), D-dimer, lactate dehydrogenase (LDH), leucocyte counts, C-reactive protein (CRP), and L-lactate were drawn before and after a standard meal. Intestinal mucosal injury was assessed with glutamine, citrulline and arginine in blood samples and compared to a sugar absorption test (SAT). Test reproducibility was validated in healthy subjects. RESULTS: Forty patients and nine healthy subjects were included. Ischemia was diagnosed in 32 patients (80%). I-FABP, leucocyte counts, LDH, CRP, glutamine, citrulline, arginine and SAT levels did not differ between patients with and without ischemia. L-lactate concentration showed a significant elevation in ischemia patients as compared to non-ischemia patients. In ischemia patients, D-dimer levels showed a significant elevation postprandially as compared to D-dimer levels at baseline. However, these ischemia patients did not show intestinal mucosal injury. CONCLUSIONS: I-FABP, leucocyte counts, LDH and CRP levels are not clinically useful for the diagnosis of CGI. However, postprandial rises in L-lactate and D-dimer serum levels can serve as non-invasive indicators of CGI.

Single-balloon-assisted colonoscopy in patients with previously failed colonoscopy.

BACKGROUND: Despite advances in training and equipment, complete colonoscopy fails, even in experienced hands, in up to 10% of cases. Double-balloon endoscopy (DBE) has been successfully used to complete colonoscopy in these patients. Single-balloon endoscopy (SBE) has become established for small-bowel enteroscopy. However, it has yet to be studied for use in colonoscopy. OBJECTIVE: To assess the efficacy, performance, and safety of single-balloon colonoscopy. DESIGN: Prospective cohort study. SETTING: Academic tertiary referral center. PATIENTS: Patients with previously failed conventional colonoscopy. RESULTS: 23 single-balloon colonoscopy procedures were performed in 22 patients: median age 53 (range 19-75) years; 14 females, 8 males. SBE colonoscopy succeeded in cecal intubation in 22 (96%) procedures, with a median total procedure time of 30 (range 20-60) minutes. SBE colonoscopy was normal in 9 cases but resulted in a positive diagnosis in 13 (57%) procedures, including polyps (n = 6), active Crohn's disease (n = 4), Crohn's-related stricture (n = 1), and diverticulosis (n = 2). Seven (30%) procedures were therapeutic including 1 case with balloon dilation and 6 cases with polypectomy. No complications were encountered. LIMITATIONS: Limited sample size, no direct comparison with double-balloon endoscopy. CONCLUSIONS: Single-balloon-assisted colonoscopy seems a safe and effective method for completing colonoscopy in patients with previously failed or difficult colonoscopy. The outcomes are similar compared with previous studies with DBE colonoscopy in this patient group.

Primary balloon-assisted enteroscopy in patients with obscure gastrointestinal bleeding: findings and outcome of therapy.

GOALS: The aim of this study was to evaluate the diagnostic and therapeutic outcome of a primary balloon-assisted enteroscopy (BAE) approach in obscure gastrointestinal bleeding (OGIB) patients. BACKGROUND: In the diagnostic approach of OGIB, both wireless capsule endoscopy (WCE) and BAE are used. The advantage of the primary wireless capsule endoscopy approach is its noninvasiveness. The main advantage of the primary BAE approach is the excellent diagnostic accuracy and the possibility to perform treatment during the same procedure. STUDY: A retrospective analysis of our BAE database with patients evaluated for OGIB was performed. BAE data, findings, and follow-up were obtained and evaluated. RESULTS: One hundred and thirty-two patients (81 male, mean age 62 (11-88) years) were included. In 60 (45%) patients with follow-up, a likely cause for OGIB was found in the small bowel during BAE: angiodysplasia or vascular malformations in 42 (70%), ulcerative lesions in 7 (12%), tumors in 3 (5%), and other findings in 8 (13%) patients. Follow-up was available in 118 (89%) patients; mean time of follow-up was 18 (1-47) months. Thirty-eight (76%) patients with findings at BAE received endoscopic treatment, 27 (71%) of them improved, but anemia also improved spontaneously in 34 patients (63%) with normal findings during BAE. The total number of angiodysplasia per patient was not related to the outcome after treatment. CONCLUSIONS: The primary BAE approach in OGIB patients has an acceptable diagnostic yield. Therapy seems successful at mid-term follow-up. A high frequency of spontaneous resolution of anemia in patients with normal findings during BAE was observed.

Impact of double-balloon enteroscopy findings on the management of Crohn's disease.

OBJECTIVE: It is estimated that 10%-30% of Crohn's disease (CD) patients have small-bowel lesions, but the exact frequency and clinical relevance of these findings are unknown. Double-balloon enteroscopy (DBE) enables endoscopic visualization of the small bowel. The aim of this study was to evaluate the use of DBE for detecting small-bowel lesions in CD patients suspected of having small-bowel involvement. Furthermore, the clinical impact of adjusting treatment in these patients was assessed. MATERIAL AND METHODS: A prospective study was performed in a tertiary referral center. CD patients suspected of small-bowel involvement and in whom distal activity had previously been excluded were included. All patients underwent DBE, followed by step-up therapy in patients with small-bowel lesions. The presence of small-bowel lesions during DBE was noted and clinical outcome was assessed after adjusting therapy. RESULTS: Thirty-five patients (70%) showed small-bowel lesions; these lesions could not be assessed by conventional endoscopy in 23 (46%). At 1-year follow-up, step-up therapy in 26 patients (74%) led to clinical remission in 23 (88%). This was confirmed by a significant decrease in Crohn's disease activity index and mucosal repair on second DBE. CONCLUSIONS: DBE showed a high frequency of small-bowel lesions in known CD patients with clinically suspected small-bowel activity. Most of these lesions were not accessible for conventional endoscopy. Adjusting treatment in patients with small-bowel CD involvement led to clinical remission and mucosal repair in the majority of cases.

Reproductive wish represents an important factor influencing therapeutic strategy in inflammatory bowel diseases.

OBJECTIVE: Inflammatory bowel disease (IBD) affects patients in reproductive age but little is known about the peri-conceptional use of medication for IBD. The aim of this study was to assess the type of medication used by IBD patients with the desire to reproduce and changes in medication in the peri-conceptional period. MATERIAL AND METHODS: IBD patients with active conception plans and pregnant patients were prospectively recruited from the outpatient clinic of a single academic medical center. IBD-related medication and changes in this medication for reasons of a desire to conceive or pregnancy were analyzed. RESULTS: In total, 61 patients (51 females; 40 with Crohn's disease, 21 with ulcerative colitis) were included. Thirteen patients (21%) used no medication, 44 (72%) used monotherapy and four (7%) used combination treatment. Of patients on monotherapy, 11 (19%) used 5-aminosalicylates, five (9%) used steroids, 11 (19%) used thiopurines, five (9%) used methotrexate and 11 (19%) used anti-tumor necrosis factor agents. Thirty-seven patients (61%) consulted a physician prior to conception. About one-third of these patients required a change in their medication due to their conception plans. CONCLUSIONS: In a referral center, the majority of IBD patients with conception plans require medication for which limited information on the safety of peri-conceptional use is available. In addition, the desire to reproduce leads to medication changes in about one-third of these patients.

Transient postprandial ischemia is associated with increased intestinal fatty acid binding protein in patients with chronic gastrointestinal ischemia.

BACKGROUND: Chronic gastrointestinal ischemia (CGI) is still a difficult diagnosis to make. Currently, the only diagnostic with an acceptable sensitivity for actual mucosal ischemia is gastrointestinal tonometry. However, tonometry is a cumbersome and invasive diagnostic test. We are in need of a more simple, noninvasive test for diagnosing mucosal ischemia. A sensitive and early serum marker could be of great use in this setting. The aim of this study was to evaluate the use of promising serum markers for mucosal ischemia [intestinal fatty acid binding protein (I-FABP), D-lactate, and lipopolysaccharide] and compared findings with corresponding gastrointestinal tonometry measurements. METHODS: Patients referred for evaluation of CGI were included. All patients had visualization of abdominal arteries and gastrointestinal tonometry. Before, during, and after tonometry blood samples were drawn for measurements of serum markers. RESULTS: Forty-nine patients were eligible for evaluation. CGI was diagnosed in 24 (49%) patients. The baseline measurements showed a significant increase in I-FABP before exercise tonometry in the abnormal-response groups compared with the normal-response group, respectively, 0.45 and 1.3 microg/l (P=0.04). An abnormal response on meal tonometry was associated with increased I-FABP levels, 1, 2, and 4 h after tonometry, compared with the patients with a normal response, respectively, 1.26, 1.11, and 0.58 microg/l (P=0.048, 0.01, and 0.03). The measurements of D-lactate and lipopolysaccharide were undetectable, or low, at all different points of time. CONCLUSION: Transient postprandial mucosal ischemia, as detected with gastrointestinal tonometry, is associated with increased I-FABP levels, indicating epithelial damage. Late markers for mucosal ischemia remained negative.

Single vessel abdominal arterial disease.

The long-standing discussion concerning the mere existence of single vessel abdominal artery disease can be closed: chronic gastrointestinal ischaemia (CGI) due to single vessel abdominal artery stenosis exists, can be treated successfully and in a safe manner. The most common causes of single vessel CGI are the coeliac artery compression syndrome (CACS) in younger patients, and atherosclerotic disease in elderly patients. The clinical symptoms of single vessel CGI patients are postprandial and exercise-related pain, weight loss, and an abdominal bruit. The current diagnostic approach in patients suspected of single vessel CGI is gastrointestinal tonometry combined with radiological visualisation of the abdominal arteries to define possible arterial stenosis. Especially in single vessel abdominal artery stenosis, gastrointestinal tonometry plays a pivotal role in establishing the diagnosis CGI. First-choice treatment of single vessel CGI remains surgical revascularisation, especially in CACS. In elderly or selected patients endovascular stent placement therapy is an acceptable option.

Therapeutic balloon-assisted enteroscopy.

Since the introduction of the first balloon-based enteroscopic technique in 2001, therapeutic balloon-assisted enteroscopy (BAE) using either the single or double balloon enteroscopy technique (respectively SBE and DBE) has evolved rapidly. Argon plasma coagulation (APC), polypectomy, dilation therapy of strictures, and therapy of the pancreatico-biliary system in patients with surgical altered proximal intestinal anatomy: all have been successfully introduced to treat pathological findings in all segments of the small bowel. The clinical impact of treatment of vascular malformations, strictures caused by chronic inflammation (especially Crohn's disease) and polypectomy therapy (especially in the Peutz-Jeghers syndrome) seems evident. The decrease of, often repeated, surgical therapy after successful therapeutic BAE in the latter 2 patient groups appears to be a big step forward in treatment. The development of newer enteroscopes, specialized equipment and improved sedation of patients adds positively to the clinical management of undergoing therapeutic BAE. The overall complication rate of therapeutic BAE seems acceptable, but is higher compared to therapeutic colonoscopy which needs further attention in future.

Twenty-four hour tonometry in patients suspected of chronic gastrointestinal ischemia.

BACKGROUND AND AIMS: Gastrointestinal tonometry is currently the only clinical diagnostic test that enables identification of symptomatic chronic gastrointestinal ischemia. Gastric exercise tonometry has proven its value for detection of ischemia in this patients group, but has its disadvantages. Earlier studies with postprandial tonometry gave unreliable results. In this study we challenged (again) the use of postprandial tonometry in patients suspected of gastrointestinal ischemia. METHODS: Patients suspected for chronic gastrointestinal ischemia had standard diagnostic work up, including gastric exercise tonometry and 24-h tonometry using standard meals. RESULTS: Thirty-three patients were enrolled in the study. Chronic gastrointestinal ischemia was diagnosed in 17 (52%) patients. The 24-h tonometry correctly predicted the presence of ischemia in 13/17 patients, and absence of ischemia in 15/16 patients. CONCLUSIONS: The use of 24-h tonometry after meals in patients suspected of gastrointestinal ischemia seems feasible, with promising accuracy for the detection of ischemia.

Triggering for submaximal exercise level in gastric exercise tonometry: serial lactate, heart rate, or respiratory quotient?

Gastric exercise tonometry is a functional diagnostic test in chronic gastrointestinal ischemia. As maximal exercise can cause false-positive tests, exercise buildup should be controlled to remain submaximal. We evaluated three parameters for monitoring and adjusting exercise levels (heart rate [HR], respiratory quotient [RQ], and serial lactate measurements) in 178 tests in both healthy volunteers and patients suspected of gastrointestinal ischemia. Exercise levels above submaximal occurred in 20% of HR-, 2% of RQ-, and 5% of lactate-monitored tests (P<0.05 for HR vs. RQ and lactate). Low levels were seen in 5% of HR-, 10% of RQ-, and 41% of lactate-monitored tests (P<0.01 for lactate vs. HR and RQ). High levels resulted in 43% false-positive tonometry results compared to 19% of all tests (P<0.001); low levels did not result in more false negatives (5% vs. 6%). Although RQ monitoring yielded the greatest proportion of optimal exercise tests, serial lactate monitoring is our method of choice, combining optimal diagnostic accuracy, low cost, and simplicity.