A new device for continuous assessment of gut perfusion: proof of concept on a porcine model of septic shock.

INTRODUCTION: We evaluate an innovative device consisting of an enteral feeding tube equipped with a photoplethysmography (PPG) sensor in contact with the duodenal mucosa. This study aims to determine if the PPG signal, composed of a continuous (PDC) and a pulsatile part (PAC), is a reliable method to assess gut perfusion in a porcine model of septic shock. METHOD: Fourteen piglets were anesthetized and mechanically ventilated. They were randomly assigned to two groups: the nonseptic (NS) group received an infusion of Ringer's lactate solution (RL) alone, the septic (S) group received in addition a suspension of live Pseudomonas aeruginosa. Heart rate (HR), pulse oximetry (SpO2), mean arterial pressure (MAP), cardiac index (CI) and serum lactates were recorded and gut microcirculation (GM) was monitored with a laser Doppler probe applied on the duodenal serosa. PDC and PAC were given by the PPG probe inserted in the duodenum. Data was collected every 15 minutes (t0, t15…) during 150 minutes (t150). After administration of the bacteria suspension (t0), resuscitation maneuvers were performed following a defined algorithm. GM PAC, and PDC were expressed as variation from baseline (GMvar, PACvar, PDCvar). Analysis of variance (ANOVA) with repeated measures was performed to compare hemodynamic variables, with Bonferroni correction as post hoc analysis on t0, t60 and t150. RESULTS: One piglet was withdrawn from analysis due to a defective probe. S group (six piglets) received resuscitation therapy while NS group (seven piglets) did not. A significant group effect was found for the all parameters except HR. Post hoc analysis found a significant decrease for GM and PAC at t60. The correlation between PAC, PDC and microcirculatory parameters were as follows: rPACvar-GMvar = 0.496, P <0.001, rPDCvar-GMvar = 0.244; P = 0.002. In the septic group, correlations were as follows: rPAC-lactate = -0.772, P <0.001; rPDC-lactate = -0.681, P <0.01). At the onset of shock, a decrease of PAC, PDC and GM occurred before the alteration of MAP. CONCLUSIONS: PAC and PDC decreased at the onset of shock and were correlated with GM and lactate. These results confirm that PPG signal reliably reflects the early perfusion alteration of the gut. Further studies should assess the clinical use of this device.

Hemodynamic assessment of celiaco-mesenteric anastomosis in patients with pancreaticoduodenal artery aneurysm concomitant with celiac artery occlusion using flow-sensitive four-dimensional magnetic resonance imaging.

OBJECTIVES: Many pancreaticoduodenal artery (PDA) aneurysms are associated with celiac artery (CA) stenosis. The pathogenesis of PDA aneurysm may be associated with hemodynamic changes due to CA stenosis/occlusion. The aim of this study was to assess the hemodynamic changes of celiaco-mesenteric anastomosis in patients with PDA aneurysms concomitant with CA occlusion using four-dimensional flow-sensitive magnetic resonance imaging (4D-Flow). METHODS: 4D-Flow was performed preoperatively on five patients. Seven age- and sex-matched individuals were used as controls. Hemodynamic parameters such as flow volume and maximum flow velocity in PDAs, gastroduodenal arteries, common hepatic arteries, and superior mesenteric arteries were compared between both groups. Wall shear stress (WSS) and oscillatory shear index (OSI) were mapped in both groups. RESULTS: In the patient group, 4D-Flow identified retrograde flow of both gastroduodenal arteries and common hepatic arteries. Heterogeneous distribution patterns of both WSS and OSI were identified across the entire PDA in the patient group. OSI mapping showed multiple regions with extremely high OSI values (OSI > 0.3) in all patients. All PDA aneurysms, which were surgically resected, were atherosclerotic. CONCLUSIONS: 4D-Flow identified hemodynamic changes in celiaco-mesenteric arteries in patients with PDA aneurysms with concomitant CA occlusion. These hemodynamic changes may be associated with PDA aneurysm formation.

Stenosis of the third portion of the duodenum due to bleeding from the anterior pancreaticoduodenal artery: assessment by multiphase contrast-enhanced examination with multislice CT.

BACKGROUND: This study was undertaken to analyze the CT findings for the rare pathological process that stenosis of the third portion of the duodenum was presumed to be caused by bleeding from the anterior pancreaticoduodenal artery. METHODS: Four consecutive patients presenting with frequent vomiting, who did not have well-known underlying disorders causing duodenal stenosis, were retrospectively recruited. Multiphase contrast-enhanced CT examinations were performed with 0.5- or 1-mm collimation. Two radiologists evaluated 2-mm axial and multiplanar reformatted images. RESULTS: In all patients, endoscopy demonstrated severe edematous stenosis of the third portion of the duodenum not associated with ulcer, bleeding, or neoplasm. The following CT findings were observed in all patients: homogenous swelling of the third portion of the duodenum associated with luminal stenosis in un-enhanced images, a band-like area of lower contrast-enhancement surrounding the walls of the third portion of the duodenum in pancreatic-phase images, and stenosis of the celiac axis. In three patients, aneurysms of the anterior pancreaticoduodenal artery in arterial-phase images were depicted. In the remaining patient, the diameter of the artery was irregular. CONCLUSIONS: Multiphase contrast-enhanced CT examination using a multislice CT scanner helps to establish the diagnosis of this pathological process.

True pancreaticoduodenal artery aneurysms: a decision analysis.

PURPOSE: True pancreaticoduodenal artery aneurysms are rare. No definitive study evaluating the natural history of these lesions or their preferred method of treatment has been published. The purpose of this study was to evaluate the outcome of preventive treatment of unruptured pancreaticoduodenal artery aneurysms using a Markov model. MATERIALS AND METHODS: With the use of a Markov model, we performed a decision analysis to evaluate the outcome of preventive treatment of unruptured pancreaticoduodenal artery aneurysms. The risk of rupture and the mortality of preventive treatment are unknown. Therefore, we performed sensitivity analysis using these parameters. Effectiveness was measured in life expectancy. RESULTS: For 80-year-old patients, preventive treatment was dominated by no treatment if mortality rates of preventive treatment were greater than 1.4%, greater than 2.6%, greater than 3.8%, and greater than 4.8% at annual rupture rates of 1%, 2%, 3%, and 4%, respectively. For 50-year-old patients, preventive treatment was dominated by no treatment if mortality rates of preventive treatment were greater than 3.3%, greater than 5.9%, greater than 8.0%, and greater than 9.7% at annual rupture rates of 1%, 2%, 3%, and 4%, respectively. CONCLUSION: The effectiveness of preventive treatment of unruptured pancreaticoduodenal artery aneurysms depends on the aneurysm rupture rate, mortality rate of preventive treatment, and patient age. Taking into account the effects of these parameters is important in making treatment decisions.

Small peripancreatic veins: improved assessment in pancreatic cancer patients using thin-section pancreatic phase helical CT.

OBJECTIVE: Recent studies have shown evaluation of the small peripancreatic veins to have potential in improving pancreatic cancer staging. This study was performed to determine the effectiveness of thin-section pancreatic phase helical CT images in visualizing these veins. MATERIALS AND METHODS: Seventy-two patients (30 with pancreatic adenocarcinoma and 42 with no pancreatic disease) underwent dual-phase helical CT with thin-section pancreatic phase acquisition (40-70 sec after i.v. contrast initiation at 3 ml/sec) and hepatic phase acquisition (70-100 sec). Visualization (with diameter measurement) or nonvisualization of the posterior superior pancreaticoduodenal vein (PSPDV), anterior superior pancreaticoduodenal vein (ASPDV), and gastrocolic trunk was recorded for both acquisitions. We also correlated surgical tumor resectability with the status of the small peripancreatic veins. RESULTS: Visualization of peripancreatic veins was significantly better on pancreatic phase images than on hepatic phase images for both healthy individuals (PSPDV, 88% of the veins visualized on the pancreatic phase images versus 50% on the hepatic phase images; ASPDV, 93% on the pancreatic phase images versus 48% on the hepatic phase images; gastrocolic trunk, 98% on the pancreatic phase images versus 76% on the hepatic phase images) and for pancreatic cancer patients (PSPDV, 97% on the pancreatic phase images versus 57% on the hepatic phase images; ASPDV, 77% on the pancreatic phase images versus 43% on the hepatic phase images) (p < .05). The exception was the gastrocolic trunk in cancer patients (83% on the pancreatic phase images versus 77% on the hepatic phase images) (p > .05). In pancreatic cancer patients, 11 dilated peripancreatic veins were identified on the pancreatic phase images compared with six on the hepatic phase images. However, only one of the 11 dilated peripancreatic veins was in a patient with surgically resectable disease. CONCLUSION: In a dual-phase helical CT protocol, thin-section pancreatic phase images provided visualization of the small peripancreatic veins that was superior to hepatic phase images, providing further support for the use of this protocol in pancreatic cancer evaluation.

Assessment of intestinal blood-flux by laser Doppler fluxmetry in mice with altered intestinal iron absorption.

Laser Doppler fluxmetry (LDF) has been used to assess mucosal blood-flux in the intestine of normal CD1 mice and groups of animals with altered iron metabolism (i.e. iron-deficient, hypoxic and hypotransferrinaemic [hpx/hpx]). All experimental animals showed a 2-3-fold increase in duodenal iron absorption, mainly due to changes in the 'mucosal transfer' phase. However, only the hypoxic mice exhibited any increases in duodenal blood-flux. In the hpx/hpx group, blood flux was maintained at control levels despite the anaemia and without any significant alterations in red blood cell velocity. Moreover, these two groups demonstrated a further capacity to increase blood-flux above basal levels during onset of acute hypoxia (inhalation of 10% O2). Changes in duodenal blood-flux were apparent on both the mucosal and serosal surfaces, suggesting that the LDF signal reflects flux throughout the thickness of the mouse intestine. Iron absorption is likely to be more related to plasma flux changes than to blood-flux changes. Deduction of plasma flux changes from blood-flux changes is complicated by vasodilation effects on capillary haematocrits. It is clear from the data, however, that plasma flux changes do not parallel changes in iron absorption in the experimental models. The lack of correlation between the duodenal blood-flux and iron absorption values in the experimental models argues against the possible involvement of blood-flux in the control of duodenal iron absorption.

[Dieulafoy's disease--an uncommon cause of severe gastrointestinal hemorrhage]. / Morbus Dieulafoy--méne castá prícina závazného krvácení do GIT.

Morbus Dieulafoy described in the European literature as exulceratio simplex, in the English and American literature as a gastric aneurysm or submucosal arterial malformation is a life endangering haemorrhage which, if treated conservatively, leads to death by exsanguination. It is haemorrhage from an aroded medium-sized or major artery with a possible mucosal defect with a minimal or no inflammatory reaction. The localization on the anterior or posterior wall of the fundus or body of the stomach is typical. There are, however, also cases of haemorrhage from a submucosal artery in other parts of the GIT--pylorus or even jejunum (3, 5). In the presented case-history the authors describe an atypically located source of haemorrhage in a parapapillary position on the descendent part of the duodenum.

Reflectance spectrophotometry for the assessment of gastroduodenal mucosal perfusion.

Reflectance spectrophotometry in assessing gastroduodenal mucosal perfusion was evaluated. Ischemia without congestion, e.g., during hemorrhagic hypotension or celiac artery occlusion, was associated with a reduction in the indexes of mucosal hemoglobin concentration and of oxygen saturation. Ischemia with congestion, e.g., during portal vein occlusion, or in absolute ethanol or suction-induced mucosal lesions, was associated with an increase in the index of mucosal hemoglobin concentration but a reduction in the index of oxygen saturation. An increase in the index of mucosal hemoglobin concentration associated with a normal index of oxygen saturation was found in the postischemic hyperemia after release of celiac artery occlusion and during the sustained increase in corpus mucosal blood flow induced by vagus nerve stimulation. Thus reflectance spectrophotometric measurements reflected ischemia, without or with congestion, and hyperemia. Additionally, although regional differences in reflectance spectrophotometric measurements were demonstrated in the duodenal, antral, and corpus mucosa, such differences bore no consistent relationship to regional differences in blood flow demonstrated in previous studies.