The association between portal system vein diameters and outcomes in acute pancreatitis.

BACKGROUND/OBJECTIVES: Acute pancreatitis (AP) progresses to necrotizing pancreatitis in 15% of cases. An important pathophysiological mechanism in AP is third spacing of fluids, which leads to intravascular volume depletion. This results in a reduced splanchnic circulation and reduced venous return. Non-visualisation of the portal and splenic vein on early computed tomography (CT) scan, which might be the result of smaller vein diameter due to decreased venous flow, is associated with infected necrosis and mortality in AP. This observation led us to hypothesize that smaller diameters of portal system veins (portal, splenic and superior mesenteric) are associated with increased severity of AP. METHODS: We conducted a post-hoc analysis of data from two randomized controlled trials that included patients with predicted severe and mild AP. The primary endpoint was AP-related mortality. The secondary endpoints were (infected) necrotizing pancreatitis and (persistent) organ failure. We performed additional CT measurements of portal system vein diameters and calculated their prognostic value through univariate and multivariate Poisson regression. RESULTS: Multivariate regression showed a significant inverse association between splenic vein diameter and mortality (RR 0.75 (0.59-0.97)). Furthermore, there was a significant inverse association between splenic and superior mesenteric vein diameter and (infected) necrosis. Diameters of all veins were inversely associated with organ failure and persistent organ failure. CONCLUSIONS: We observed an inverse relationship between portal system vein diameter and morbidity and an inverse relationship between splenic vein diameter and mortality in AP. Further research is needed to test whether these results can be implemented in predictive scoring systems.

Long-Term Results of Endovascular Treatment of Atherosclerotic Stenoses or Occlusions of the Coeliac and Superior Mesenteric Artery in Patients With Mesenteric Ischaemia.

INTRODUCTION: Over the past decade, primary percutaneous mesenteric artery stenting (PMAS) has become an alternative to open revascularisation for treatment of mesenteric ischaemia. Institutes have presented favourable short-term outcomes after PMAS, but there is a lack of data on long-term stent patency. METHODS: One hundred and forty-one patients treated by PMAS for acute and chronic mesenteric ischaemia over an 8 year period were studied. Anatomical success was assessed by duplex ultrasound and/or CT angiography. A stenosis ≥70% was considered to be a failure. RESULTS: Eighty-six coeliac arteries (CA) and 99 superior mesenteric arteries (SMA) were treated with PMAS in 141 patients. Nine CAs (10%) and 30 SMAs (30%) were occluded at the time of treatment. Median follow-up was 32 months (IQR 20-46). The overall primary patency rate at 12 and 60 months was 77.0% and 45.0%. The overall primary assisted patency rate was 90.3% and 69.8%. Overall secondary patency was 98.3% and 93.6%. CONCLUSION: This study shows excellent long-term secondary patencies after PMAS, comparable with published data on long-term patencies after open surgical revascularisation.

Splanchnic artery stenosis and abdominal complaints: clinical history is of limited value in detection of gastrointestinal ischemia.

BACKGROUND: Splanchnic artery stenosis is common and mostly asymptomatic and may lead to gastrointestinal ischemia (chronic splanchnic syndrome, CSS). This study was designed to assess risk factors for CSS in the medical history of patients with splanchnic artery stenosis and whether these risk factors can be used to identify patients with high and low risk of CSS. METHODS: All patients referred for suspected CSS underwent a standardized workup, including a medical history with questionnaire, duplex ultrasound, gastrointestinal tonometry, and angiography. Definitive diagnosis and treatment advice was made in a multidisciplinary team. Patients with confirmed CSS were compared with no-CSS patients. RESULTS: A total of 270 patients (102 M, 168 F; mean age, 53 years) with splanchnic artery stenosis were analyzed, of whom 109 (40%) had CSS and 161 no CSS. CSS-patients more often reported postprandial pain (87% vs. 72%, p = 0.007), weight loss (85% vs. 70%, p = 0.006), adapted eating pattern (90% vs. 79%, p = 0.005) and diarrhea (35% vs. 22%, p = 0.023). If none of these risk factors were present, the probability of CSS was 13%; if all were present, the probability was 60%. Adapted eating pattern (odds ratio (OR) 3.1; 95% confidence interval (CI) 1.08-8.88) and diarrhea (OR 2.6; 95% CI 1.31-5.3) were statistically significant in multivariate analysis. CONCLUSIONS: In patients with splanchnic artery stenosis, the clinical history is of limited value for detection of CSS. A diagnostic test to detect ischemia is indispensable for proper selection of patients with splanchnic artery stenosis who might benefit from treatment.

Predictors for neoplastic progression in patients with Barrett's Esophagus: a prospective cohort study.

OBJECTIVES: Patients with Barrett's esophagus (BE) have an increased risk of developing esophageal adenocarcinoma (EAC). As the absolute risk remains low, there is a need for predictors of neoplastic progression to tailor more individualized surveillance programs. The aim of this study was to identify such predictors of progression to high-grade dysplasia (HGD) and EAC in patients with BE after 4 years of surveillance and to develop a prediction model based on these factors. METHODS: We included 713 patients with BE (≥ 2 cm) with no dysplasia (ND) or low-grade dysplasia (LGD) in a multicenter, prospective cohort study. Data on age, gender, body mass index (BMI), reflux symptoms, tobacco and alcohol use, medication use, upper gastrointestinal (GI) endoscopy findings, and histology were prospectively collected. As part of this study, patients with ND underwent surveillance every 2 years, whereas those with LGD were followed on a yearly basis. Log linear regression analysis was performed to identify risk factors associated with the development of HGD or EAC during surveillance. RESULTS: After 4 years of follow-up, 26/713 (3.4%) patients developed HGD or EAC, with the remaining 687 patients remaining stable with ND or LGD. Multivariable analysis showed that a known duration of BE of ≥ 10 years (risk ratio (RR) 3.2; 95% confidence interval (CI) 1.3-7.8), length of BE (RR 1.11 per cm increase in length; 95% CI 1.01-1.2), esophagitis (RR 3.5; 95% CI 1.3-9.5), and LGD (RR 9.7; 95% CI 4.4-21.5) were significant predictors of progression to HGD or EAC. In a prediction model, we found that the annual risk of developing HGD or EAC in BE varied between 0.3% and up to 40%. Patients with ND and no other risk factors had the lowest risk of developing HGD or EAC (<1%), whereas those with LGD and at least one other risk factor had the highest risk of neoplastic progression (18-40%). CONCLUSIONS: In patients with BE, the risk of developing HGD or EAC is predominantly determined by the presence of LGD, a known duration of BE of ≥10 years, longer length of BE, and presence of esophagitis. One or combinations of these risk factors are able to identify patients with a low or high risk of neoplastic progression and could therefore be used to individualize surveillance intervals in BE.

Pancreatic ductal adenocarcinoma and chronic pancreatitis may be diagnosed by exhaled-breath profiles: a multicenter pilot study.

BACKGROUND: The diagnosis of pancreatic adenocarcinoma and chronic pancreatitis often rely on expensive and invasive diagnostic approaches, which are not always discriminative since patients with chronic pancreatitis and pancreatic adenocarcinoma may present with similar symptoms. Volatile organic compounds (VOCs) in expired breath, could be used as a non-invasive diagnostic biological marker for detection of pancreatic pathology. Detection and discrimination of pancreatic pathology with an electronic nose has not yet been reported. PURPOSE: The objective of this pilot study was to determine the diagnostic potential of an electronic nose to identify pancreatic adenocarcinoma and chronic pancreatitis by analyzing volatile organic compoundg (VOC) profiles in exhaled air. PATIENTS AND METHODS: In a multicenter study, the exhaled air of 56 chronic pancreatitis patients, 29 pancreatic adenocarcinoma patients, and 74 disease controls were analyzed using an electronic nose based on 3 metal oxide sensors (MOS). The measurements were evaluated utilizing an artificial neural network. RESULTS: VOC profiles of chronic pancreatitis patients could be discriminated from disease controls with an accuracy of 0.87 (AUC 0.95, sensitivity 80%, specificity 92%). Also, VOC profiles of patients with pancreatic adenocarcinoma differed from disease controls with an accuracy of 0.83 (AUC 0.87, sensitivity 83%, specificity 82%). Discrimination between chronic pancreatitis and pancreatic adenocarcinoma showed an accuracy of 0.75 (AUC 0.83, sensitivity 83%, specificity 71%). CONCLUSION: An electronic nose may be a valuable diagnostic tool in diagnosis of pancreatic adenocarcinoma and chronic pancreatitis. The current study shows the potential of an electronic nose for discriminating between chronic pancreatitis, pancreatic adenocarcinoma and healthy controls. The results from this proof-of-concept study warrant external validation in larger cohorts.

The Impact of Revascularisation on Quality of Life in Chronic Mesenteric Ischemia.

Background: Chronic mesenteric ischemia (CMI) is characterized by long-standing abdominal symptoms due to insufficient mesenteric circulation. Data on the effect of revascularisation on quality of life (QoL) for CMI are scarce. This study is the first to evaluate the impact of revascularisation on quality of life. Methods: Seventy-nine patients with CMI or acute-on-chronic mesenteric ischemia (AoCMI) underwent an intervention of one or more mesenteric arteries between January 2010 and July 2012. QoL before and after intervention was measured with the EuroQol-5D. Preintervention questionnaires were of standard care. Postintervention data were obtained by resending a questionnaire to the patients between February and May 2013. To investigate the clinical relevance of our findings, the minimal clinically important difference (MCID) was used. Since there is no established MCID for CMI, we used the literature reference MCID of inflammatory bowel syndrome (IBS) of 0.074. Results: Fifty-five (69.6%) of 79 patients returned their questionnaire and 23 (29.1%) were completely filled out. There was a significant increase of the median EQ-index score from 0.70 to 0.81 (p=0.02) and a significant reduction of symptoms in the domains usual activities (34.4%) and pain/discomfort (32.3%). There was a significant improvement of 17% in overall current health condition (VAS) (p=0.001). The MCID between baseline and postoperative EQ-5D index score was 0.162, indicating a clinically relevant improvement of quality of life after revascularisation. Conclusion: Quality of life of CMI patients is improved after mesenteric artery revascularisation.

Comparison of usefulness of C-reactive protein versus white blood cell count to predict outcome after primary percutaneous coronary intervention for ST elevation myocardial infarction.

White blood cell (WBC) count and high-sensitive C-reactive protein (hs-CRP) are both used as markers of inflammation and prognosis after an ST elevation myocardial infarction (STEMI), but it is unknown whether they have independent prognostic value. We investigated the association and independent prognostic importance of WBC and hs-CRP after STEMI. In this subanalysis of the On-TIME trial, in 490 of 507 (97%) patients, either WBC count or CRP, and in 362 (71%) patients, both WBC count and CRP, were measured on admission before primary percutaneous coronary intervention. There was no significant correlation between WBC count and CRP (R = 0.080). Higher levels of CRP were associated with a reinfarction or death within 1 year (mean hs-CRP 14.2 +/- 20.4 vs 6.1 +/- 14.2, p = 0.006), but CRP was not associated with enzymatic infarct size (lactate dehydrogenase, LDHQ48) or left ventricular ejection fraction. A higher baseline WBC count was associated with larger LDHQ48 and lower left ventricular ejection fraction but not with 1-year reinfarction or death. In conclusion, although both WBC count and CRP are markers of inflammation and predictors of outcome after STEMI, we did not find a correlation between baseline WBC count and CRP levels in patients treated with primary percutaneous coronary intervention for STEMI. The mechanisms by which WBC counts predict outcome were related to myocardial infarct size whereas CRP were not.

[Gastrointestinal ischaemia during physical exertion as a cause of gastrointestinal symptoms]. / Maag-darmischemie tijdens lichamelijke inspanning als oorzaak van gastro-intestinale klachten.

Gastrointestinal (GI) symptoms are reported by up to 70% of endurance athletes. Although exercise leads to decreased gastrointestinal blood flow, GI-ischaemia is rarely reported as a cause. Mucosal ischaemia may result in nausea, abdominal cramps and bloody diarrhoea. After exercise, reperfusion damage and endotoxaemia may cause systemic symptoms as well. In three patients, two women aged 46 and 25 respectively and a man aged 40, with a heterogeneous presentation of exercise induced GI-symptoms, GI-ischaemia was demonstrated using gastric exercise tonometry. Gastric tonometry is mandatory for the diagnosis and follow-up. In the first patient, an isolated celiac artery stenosis was found; after incision of the left crus of the diaphragm, she was asymptomatic and the results of gastric tonometry improved. The other two patients had non-occlusive ischaemia associated with high exercise intensity. Reduction of the exercise intensity resulted in the complaints disappearing.

Acute stress-related gastrointestinal ischemia.

We report a case of acute gastrointestinal ischemia during a very stressful event in whom the diagnosis was made by 24-hour tonometry. This case report unequivocally links a stressful event with increased catecholamine release and subsequent severe symptomatic gastrointestinal ischemia. The role of ischemia as potential pathophysiological mechanism has never been studied in detail. The clinical significance of finding such an association is underscored by this case report, where a vasoactive drug normally used for hypertension treatment resulted in greatly improved abdominal symptoms.

Platelet microaggregation inhibition in patients with acute myocardial infarction pretreated with tirofiban and relationship with angiographic and clinical outcome.

BACKGROUND: The relationship between the level of platelet aggregation inhibition in patients with acute myocardial infarction and their clinical outcome is unknown. METHODS: In patients with acute myocardial infarction included in the On-TIME trial and transferred to the primary percutaneous coronary intervention (PCI) center of Zwolle, who were pretreated with tirofiban on top of acetylsalicylic acid and heparin, platelet microaggregation inhibition was assessed on admission and immediately after PCI, using the Sysmex K4500 (Sysmex Corp, Kobe, Japan) platelet microaggregation measurement. The level of platelet microaggregation inhibition was compared with angiographic and clinical outcome. Patients were randomized to early prehospital initiation of tirofiban or to initiation in the catheterization laboratory. Therefore, the effect of tirofiban on platelet microaggregation inhibition could additionally be determined by measuring baseline platelet microaggregation also at entrance into the hospital. RESULTS: In 412 (89%) of 463 patients, platelet microaggregation inhibition was measured after receiving tirofiban. There was no difference between the 4 quartiles of the level of platelet microaggregation inhibition with regard to distal embolization, TIMI-3 flow and blush grade 3 after PCI, mean corrected TIMI frame count, ejection fraction, enzymatic infarct size, and percentage ST-segment resolution (P values .91, .97, .46, .94, .73, .33, and .72, respectively). The baseline platelet microaggregation inhibition in patients treated with tirofiban was 38% +/- 25% (mean +/- SD), and in the patients treated with placebo, 14% +/- 22% (P < .001). CONCLUSIONS: We found no correlation between the level of platelet microaggregation inhibition after tirofiban and outcome, whereas only a modest increase in platelet microaggregation inhibition was observed after a commonly used dose of tirofiban.

Incidence and predictors of subacute thrombosis in patients undergoing primary angioplasty for an acute myocardial infarction.

Subacute thrombosis (SAT) is a major concern in patients undergoing percutaneous coronary intervention (PCI). So far, only little data has been available on characteristics and outcome of patients with SAT after primary PCI for ST elevation myocardial infarction (STEMI). From 1997-2001, 1,548 unselected consecutive patients underwent primary PCI for STEMI as part of a randomized controlled trial stenting vs. balloon angioplasty. All patients received acetylsalicylic acid (500 mg i.v.) and heparin (5,000 IU) before the procedure. After stenting, all patients received ticlopidine 250 mg daily (before July 1999) or clopidogrel 75 mg daily (after July 1999) for one month. Five percent of patients received glycoprotein IIb/IIIa blockers. We prospectively recorded incidence and characteristics of patients with SAT during one year follow-up. SAT occurred in 4.1% (63/1548) and reinfarction in 6.0% of patients. The incidence of SAT did not change over time (1997: 8/175[4.6%],1998: 8/325 [2.5%],1999: 13/358 [3.6%], 2000: 22/426 [5.2%], 2001: 12/264 [4.5%]). SAT occurred in 39/63(62%) patients during hospital stay. The incidence did not differ between patients after ticlopidine 23/681 (3.4%) or clopidogrel 40/867 (4.6%, p = 0.222). Univariate predictors of SAT were: patients with an LAD stenosis (5.4% vs. 2.9%, p = 0.016), with Killip class >1 at presentation (8.6% vs. 3.7%, p = 0.007) and in patients who received a stent (5.1% vs. 2.7%, p = 0.022). After multivariate analysis, Killip class >1 on admission was the only independent predictor of SAT(OR 2.26, 95% CI 1.14-4.47, p = 0.019). SAT was associated with a higher mortality at long-term follow-up (15% vs. 7%, p = 0.026). In a prospectively recorded, unselected consecutive series of patients undergoing PCI for STEMI, SAT occurred in 4.1% of patients at one-year follow-up. Signs of heart failure on admission, anterior myocardial infarction and stenting were predictors of SAT.

Dutch endoscopic capacity in the era of colorectal cancer screening.

BACKGROUND: Future colorectal cancer (CRC) screening programmes should not (greatly) interfere with regular health care. Hence, we analysed the Dutch endoscopic practice to provide a clear insight into endoscopic workload and manpower with a special emphasis on the current ability to facilitate a successful implementation of a faecal occult blood test (FOBT)-based nationwide CRC screening programme. METHODS: A questionnaire was sent to all Dutch endoscopy units (n = 100) in the spring of 2005. The questionnaire included topics ranging from the numbers and specifications of endoscopies performed in 2004 and the numbers of endoscopists per unit to expected vacancies for gastroenterologists and waiting times. RESULTS: The response rate was 98%, representing a total of 49,253 hospital beds. overall, a 26% increase in the number of endoscopies from 325,000 in 1999 to almost 410,000 in 2004 was found, accompanied by a 25% increase in manpower. The total number of endoscopists was 598. regional differences were observed in the number of endoscopists, the total number of endoscopies and colonoscopies, and the number of endoscopies per endoscopist. A biannual FOBT-based screening programme would yield an additional workload of 25,385 colonoscopies a year amounting to a 22% increase in the total number of colonoscopies performed. However, the workload per unit would only have to increase by five extra colonoscopies a week. CONCLUSION: Whereas an FOBT-based CRC screening programme is currently feasible without strongly interfering with regular health care, future plans regarding the scale and preferred mode of screening should incorporate solid data on the (regional) endoscopic capacity and manpower needed for a successful implementation.

Microscopic colitis: prevalence and distribution throughout the colon in patients with chronic diarrhoea.

BACKGROUND: Microscopic colitis presents with chronic diarrhoea with or without abdominal pain. Microscopic colitis is an important cause of chronic diarrhoea. It can be distributed throughout the colon, as well as limited to the right colon. Microscopic colitis is associated with coeliac disease. We studied the prevalence and distribution of microscopic colitis in patients with diarrhoea and normal colonoscopy and we studied the association with coeliac disease. METHODS: Colonoscopy was performed. Biopsies were taken from every segment of the colon. Lymphocytic colitis was defined as the presence of more than 20 lymphocytes per 100 epithelial cells and collagenous colitis was defined as thickening of the basal membrane of more than 10 microm. Upper endoscopy was performed if upper intestinal symptoms were present. If this was the case, small bowel biopsies were taken. RESULTS: Microscopic colitis was found in 13 out of 103 patients. The distribution was diffuse throughout the colon in ten and restricted to the right colon in three patients. In seven patients, upper endoscopy was performed. Marsh I/II lesions were found in six out of seven patients. CONCLUSION: Microscopic colitis was limited to the right colon in 23% of patients. Biopsies of macroscopically normal colonic mucosa in patients with diarrhoea is mandatory.

Ranitidine bismuth citrate with clarithromycin versus omeprazole with amoxycillin in the cure of Helicobacter pylori infection.

AIM: To compare the efficacy of ranitidine bismuth citrate plus clarithromycin (RBC-C) vs. omeprazole plus amoxycillin (OME-AMO) in the cure of Helicobacter pylori infection. METHODS: In this double-blind, multicentre, parallel-group study 122 H. pylori-positive patients with active duodenal ulcer or gastritis, with confirmed history of duodenal ulcer, were randomized to treatment with ranitidine bismuth citrate 400 mg b.d. plus clarithromycin 500 mg b.d. or omeprazole 20 mg b.d. plus amoxycillin 1000 mg b.d. for 14 days, followed by 14 days of ranitidine bismuth citrate 400 mg b.d. or omeprazole 20 mg once daily, respectively, to facilitate ulcer healing. Endoscopy was carried out at the start of the study and 28 days after the end of treatment. At each endoscopy four biopsies were obtained from the antrum and four biopsies from the corpus, for rapid urease test, histology and culture. H. pylori infection was defined as a positive urease test, confirmed by histology or culture. Cure of H. pylori infection was defined as negative urease test, histology or culture from both sites. RESULTS: Per-protocol, all-patients-treated and intention-to-treat cure rates (95% confidence interval) were, respectively, 90% (81-89%), 90% (82-89%) and 84% (74-93%) for ranitidine bismuth citrate plus clarithromycin, and 39% (27-54%), 44% (31-57%) and 41% (29-53%) for omeprazole plus amoxycillin, P < 0.00001. Both regimens were well tolerated. Eight patients were lost to follow-up, for lack of efficacy (one patient), adverse events (three patients) or refusal of second endoscopy (four patients). CONCLUSION: Ranitidine bismuth citrate 400 mg b.d. with clarithromycin 500 mg b.d. is superior to omeprazole 20 mg b.d. with amoxycillin 1000 mg b.d. Ranitidine bismuth citrate with clarithromycin is the first dual therapy with high cure rates and good tolerance, and is easy to take. It may therefore prove a suitable first-line treatment in H. pylori infection.

Type of solution and PCO2 measurement errors during tonometry.

OBJECTIVE: The choice of solution for gastrointestinal tonometry influences the PCO2 measurement bias, precision and the time required for equilibration. We compared saline with buffered solutions during in vitro tonometry, with respect to systematic and accidental measurement errors and equilibration time. DESIGN: A prospective laboratory study. MEASUREMENTS: Saline, phosphate, phosphate bicarbonate and succinylated gelatin solutions were equilibrated in a specialized blood gas tonometer at PCO2s of 2.7, 3.6, 4.5, 6.2 and 9.0 kPa, using calibration gases. Accidental errors were determined: the within-syringe decline of PCO2 and the effects of handling errors (five up and down movements of the plunger). The PCO2 build up in gastrointestinal tonometers was determined in 5000 ml saline baths with fixed PCO2 levels of 2.7 and 9.0 kPa. RESULTS: The build up of PCO2 in phosphate bicarbonate and gelatin was about 4 and 2 times slower than in saline and phosphate, respectively, both for gas and gastrointestinal tonometers. The bias of the measured PCO2 at equilibrium was -15% for saline, and between -1 and 3% for phosphate, phosphate bicarbonate and gelatin. The precision was comparable among the solutions: 2 +/- 1% for saline, 2 +/- 1% for phosphate, 1 +/- 0% for phosphate bicarbonate and 1 +/- 1% for gelatin. The accidental errors were virtually absent with phosphate bicarbonate, intermediate with gelatin and largest with saline and phosphate. CONCLUSION: Phosphate bicarbonate buffer and succinylated gelatin allow accurate PCO2 measurements, but their equilibration is too slow for clinical application. The advantage of phosphate over saline solution is a smaller bias only. Thus, both saline and phosphate are currently the tonometer solutions of choice, provided that strictly anaerobic conditions are applied and the bias by the blood gas analyzer is known.

Reliable gastric tonometry after coronary artery surgery: need for acid secretion suppression despite transient failure of acid secretion.

OBJECTIVE: To study the need for suppression of gastric acid secretion for reliable intragastric partial pressure of carbon dioxide (PCO2) tonometry by evaluating the effect of an oral dose of sodium bicarbonate before and after administration of the H2-blocker ranitidine to mimic CO2 generation following the buffering of acid by bicarbonate in patients after cardiac surgery. DESIGN: Prospective, open, non-randomized clinical study. SETTING: Cardiothoracic intensive care unit at a university hospital. PATIENTS: 10 patients after elective coronary artery bypass surgery. INTERVENTIONS: An oral dose of 500 mg sodium bicarbonate before and after acid secretion suppression by 100 mg ranitidine as an intravenous bolus given at approximately 3 h after surgery (day 0) and on the first postoperative day (day 1). MEASUREMENTS AND RESULTS: Intragastric PCO2 (iPCO2; tonometry), gastric juice pH (aspirate) and arterial blood gas values were measured. On day 0, the iPCO2 was 25 +/- 5 mmHg before and 31 +/- 5 mmHg after the bicarbonate dose, 29 +/- 5 mmHg after ranitidine infusion, and 31 +/- 5 mmHg after the bicarbonate dose following the ranitidine infusion (NS). On day 1, the basal iPCO2 was 32 +/- 4 mmHg and it increased to 56 +/- 25 mmHg following bicarbonate (p < 0.01). After ranitidine, the iPCO2 was 33 +/- 4 mmHg before and 40 +/- 14 mmHg after bicarbonate (NS). Basal gastric juice pH was > 4 in nine of ten patients on day 0 and > 4 in seven of ten patients on day 1. CONCLUSIONS: Pharmacological suppression of gastric acid secretion is mandatory for reliable iPCO2 tonometry after cardiopulmonary bypass surgery, even when gastric acid secretion is transiently inhibited. In fact, gastric acid secretion was inhibited immediately after surgery, but returned on the first postoperative day in most patients, as judged from the bicarbonate back titration of gastric acid, even when gastric juice pH was relatively high.

Exercise induces gastric ischemia in healthy volunteers: a tonometry study.

Heavy physical exercise may cause gastrointestinal signs and symptoms, and, although splanchnic blood flow may decrease through redistribution by more than 50%, it is unclear whether these signs and symptoms relate to gastrointestinal ischemia. In 10 healthy volunteers, we studied the effect of exercise on gastric mucosal perfusion adequacy using air tonometry. Two relatively short (10 min) exercise stages were conducted on a cycle ergometer, aiming for 80 and 100% of maximum heart rate, respectively. The intragastric-arterial PCO(2) gradient (Delta PCO(2)) was elevated by 1.1 +/- 1.0 kPa over baseline values (-0.1 +/- 0.3 kPa) only after maximal exercise (P < 0.001). Delta PCO(2) positively correlated with the arterial lactate level taken as an index of exercise intensity (Spearman's rank test: r = 0.76, P < 0.0001). By bilinear regression analysis, a lactate level of 12 mmol/l, above which a sharp rise in the Delta PCO(2) occurred, was calculated. We conclude that, in healthy volunteers with normal splanchnic vasculature, gastric ischemia may develop during maximal exercise as judged from intragastric PCO(2) tonometry.

Mechanism of clarithromycin resistance in clinical isolates of Helicobacter pylori.

Seventy-three Helicobacter pylori-positive patients were treated with a combination of clarithromycin and ranitidine in order to eradicate the bacterium. Eradication was successful in 79.5%. In 15 patients eradication failed, and in 11 cases this was due to clarithromycin resistance. In one patient the infecting strain was resistant at the onset of treatment, while in the remaining 10 patients resistance developed during therapy. These isolates had also become resistant to various other antibiotics. Random amplified polymorphic DNA and restriction fragment end-labeling analysis of the isolates showed close genetic relatedness between pre- and post-treatment isolates, indicating that resistance was the result of selection of variants of the infecting strain rather then infection with an exogenous resistant strain. Nucleotide sequence comparisons revealed that all resistant isolates had a single base pair mutation in the 23S rRNA. Since this single point mutation results in co-resistance to various antibiotics at high frequencies, caution should be taken when using clarithromycin as a single antibiotic.

Splanchnic tonometry: a review of physiology, methodology, and clinical applications.

The objective of this article is to review splanchnic tonometry. The English literature, involving both animal and human studies, was used for review, with emphasis on papers on physiological and methodological principles and clinical applications. Tonometry involves the measurement of intraluminal PCO2 as a measure of mucosal PCO2 in the gastrointestinal tract via a catheter in, for instance, stomach or sigmoid colon, and the calculation, with help of the blood bicarbonate content and the Henderson-Hasselbalch equation, of the mucosal pH (pHi). The latter is considered as a relatively simple index of the adequacy of mucosal blood flow. Concerning methodology, it is still unclear whether acid secretion should be inhibited for proper assessment of PCO2 in the stomach. Buffering of bicarbonate by gastric acid may elevate the intraluminal PCO2 independently from mucosal PCO2, thereby confounding pHi as a measure of perfusion adequacy. This can be prevented by inhibition of acid secretion. Authors have raised doubts whether the composite variable pHi is of additive value to the acid-base status of arterial blood, so that it is unclear whether a subnormal pHi is a specific and sensitive indicator of mucosal ischemia, as suggested by others on the basis of a decline in the pHi along the gastrointestinal tract in animals subjected to vascular occlusion or circulatory shock. Moreover, tissue PCO2 depends on the PCO2 of supplying blood. Conversely, the bicarbonate concentration in ischemic mucosa may not equal that in arterial blood. Taken together, an elevated tonometer fluid arterial blood PCO2-gradient might be a more sensitive and specific indicator of mucosal ischemia than a decrease in the pHi, analogous to an increase in tissue PCO2 and widening of the venoarterial PCO2 gradient during various types of hypoperfusion, in animals and humans. Although splanchnic ischemia is an early event in shock, the sensitivity and specificity of this index for mucosal ischemia and its clinical value, relative to that of the pHi, have not been formally evaluated yet. Nevertheless, the pHi has been suggested to be of predictive value for gastrointestinal complications, multiple organ failure, success or failure of weaning from mechanical ventilation, and outcome in critically ill patients. Tonometry may be a useful monitoring technique to guide treatment and to improve survival. Splanchnic tonometry is a relatively simple, noninvasive, and thereby promising technique to monitor the critically ill. However, some aspects need further evaluation before the technique can be advocated for routine use.