Initial hepatosplanchnic blood flow distribution and oxygen metabolism in experimental model of hypotensive brain death

Background: Organs from the so-called marginal donors have been used with a significant higher risk of primary non function than organs retrieved from the optimal donors. We investigated the early metabolic changes and blood flow redistribution in splanchnic territory in an experimental model that mimics marginal brain-dead (BD) donor. Material/Methods: Ten dogs (21.3 +/- 0.9 kg), were subjected to a brain death protocol induced by subdural balloon inflation and observed for 30 min thereafter without ally additional interventions. Mean arterial and intracranial pressures, heart rate, cardiac output (CO), portal vein and hepatic artery blood flows (PVBF and HABF, ultrasonic flowprobe), and O(2)-derived variables were evaluated. Results: An increase in arterial pressure, CO, PVBF and HABF was observed after BD induction. At the end, an intense hypotension with normalization in CO (3.0 +/- 0.2 VS. 2.8 +/- 2.8 L/min) and PVBF (687 +/- 114 vs. 623 +/- 130 ml/min) was observed, whereas HABF (277 33 vs. 134 28 ml/min, p<0.005) remained lower than baseline values. Conclusions: Despite severe hypotension induced by sudden increase of intracranial pressure, the systemic and splanchnic blood flows were partially preserved without signs of severe hypoperfusion (i.e. hyperlactatemia). Additionally, the HABF was mostly negatively affected in this model of marginal BD donor. Our data suggest that not only the cardiac output, but the intrinsic hepatic microcirculatory mechanism plays a role in the hepatic blood flow control after BD.

Elevation of Uterine Basal Tone and Fetal Heart Rate Abnormalities After Labor Analgesia A Randomized Controlled Trial

OBJECTIVE: To estimate the effects of combined spinal-epidural and traditional epidural analgesia on uterine basal tone and its association with the occurrence of fetal heart rate (FHR) abnormalities. METHODS: Seventy-seven laboring patients who requested pain relief during labor were randomly assigned to combined spinal-epidural (n=41) or epidural analgesia (n=36). Uterine contractions and FHR were recorded 15 minutes before and after analgesia. Uterine tone was evaluated with intrauterine pressure catheter. Primary outcomes were the elevation of baseline uterine tone and occurrence of FHR prolonged decelerations or bradycardia after analgesia. The influence of other variables such as oxytocin use, hypotension, and speed of pain relief were estimated using a logistic regression model. RESULTS: The incidence of all outcomes was significantly greater in the combined spinal-epidural group compared with epidural: uterine hypertonus (17 compared with 6; P=.018), FHR abnormalities (13 compared with 2; P<.01), and both events simultaneously (11 compared with 1; P<.01). Logistic regression analysis showed the type of analgesia as the only independent predictor of uterine hypertonus (odds ratio 3.526, 95% confidence interval 1.21-10.36; P=.022). For the occurrence of FHR abnormalities, elevation of uterine tone was the independent predictor (odds ratio 18.624, 95% confidence interval 4.46-77.72; P<.001). Regression analysis also found a correlation between decrease on pain scores immediately after analgesia and the estimated probability of occurrence of hypertonus and FHR abnormalities. CONCLUSION: Combined spinal-epidural analgesia is associated with a significantly greater incidence of FHR abnormalities related to uterine hypertonus compared with epidural analgesia. The faster the pain relief after analgesia, the higher the probability of uterine hypertonus and FHR changes. CLINICAL TRIAL REGISTRATION: Umin Clinical Trials Registry, http://www.umin.ac.jp/ctr/index.htm, UMIN000001186

The ventriculoomental bursa shunt

Object The aim of this study is to access the efficacy of the omental bursa (lesser sac) as a receptacle of cerebrospinal fluid (CSF) and to use it as an alternative to the ventriculoatrial or ventriculopleural shunts when the peritoneum reduces or loses its CSF absorption capacity. Methods Three patients with hydrocephalus presented with malfunctioning of ventriculoperitoneal shunts, secondary to peritoneal blockage caused by previous episodes of shunt infections in two and peritonitis in one patient. All patients underwent previous shunt revisions due to ventriculitis and shunt obstruction ranging from three to eight times. In order to keep the peritoneal cavity as the main receptacle of CSF absorption site, the distal catheter was inserted in the omental bursa, through the foramen of Winslow, jointly by a pediatric surgeon. We denominated this new technique of CSF diversion as ventriculoomental bursa (VOB) shunting. The children have been followed at least for 1 year (range 12 to 28 months) with no recurrence of shunt. Conclusions VOB shunting may be considered an acceptable technique to CSF shunting when the anterior peritoneum loses or decreases its CSF absorption capacity.

Effects of sinoaortic Denervation on Hemodynamic parameters during natural sleep in rats

Study Objectives: To analyze the role of arterial baroreflex on hemodynamic changes during synchronized and desynchronized sleep phases of natural sleep in rats. Design: Experimental study. Setting: Laboratory. Participants: Seventeen male Wistar rats. Interventions: No intervention (control, n = 8) or sinoaortic denervation (SAD, n = 9). Measurements and Results: Sleep phases were monitored by electrocorticogram, and blood pressure was measured directly by a catheter in the carotid artery. Cardiac output, as well as total and regional vascular resistances, were determined by measuring the subdiaphragmatic aorta and iliac artery flows with Doppler flow probes, respectively. In contrast to the control group, the SAD group had a strong reduction in blood pressure (-19.9% +/- 2.6% vs -0.7% +/- 2.1%) during desynchronized sleep, and cardiac output showed an exacerbated reduction (-10.4% +/- 3.5% vs 1.1% +/- 1.7%). In SAD rats, total vascular resistance decreased during desynchronized sleep (-10.1% +/- 3.5% vs -1.0% +/- 1.7%), and the increase in regional vascular resistance observed in the control group was abolished (27.5% +/- 8.3% vs -0.8% +/- 9.4%). Conclusions: SAD caused profound changes in blood pressure, cardiac output, and total vascular resistance, with a significant increase in muscle vascular resistance during synchronized sleep. Our results suggest that baroreflex plays an important role in maintaining the normal balance of cardiac output and total vascular resistance during sleep.

Is Silver Nitrate Pleurodesis for Patients with Malignant Pleural Effusion Feasible and Safe When Performed in an Outpatient Setting?

The purpose of this study was to analyze the effectiveness and safety of silver nitrate pleurodesis (SNP) in patients with recurrent malignant pleural effusion (RMPE) when performed in an outpatient setting. Prospective study including patients with RMPE recruited in a tertiary university-based hospital from February 2008 to June 2009. Elected patients underwent pleural catheter insertion (Day 1) followed by 0.5% SNP (Day 2), and on 7th day the drain was removed. All procedures were performed in an outpatient facility. Pleurodesis was considered successful when no additional pleural procedure was necessary by the 30th day. Complications were registered and graded according to the CTCAE3.0. Quality of life was evaluated before and 30 days after SNP. A total of 68 patients (54 female, 14 male, mean age: 57.3 years) were included. In addition, 7 had bilateral pleural effusions; therefore, 75 hemithoraces were drained. Also, 5 were excluded, and 70 hemithoraces (63 patients) underwent SNP. During the period of 30 days postpleurodesis, 8 deaths not related to the procedure occurred, and we lost contact with 10 patients who were followed elsewhere. At the 30th day, 48 hemithoraces (45 patients) were reevaluated, and 2 recurrences observed. The most frequent complication was pain-graded as 3 or more in 7 patients; infection occurred in 2 patients. Physical and environmental aspects of quality of life improved significantly after pleurodesis. In this study, SNP could be performed safely in an outpatient setting, with pain the most frequent complication. Recurrences occurred in 4% of the patients.

Biofilms, Infection, and Parenteral Nutrition Therapy

Parenteral nutrition therapy is used in patients with a contraindication to the use of the gastrointestinal tract, and infection is one of its Frequent and severe complications. The objective of the present study was to detect the presence of biofilms and microorganisms adhering to the central venous. catheters used for parenteral nutrition therapy by scanning electron microscopy. Thirty-nine central venous catheters belonging to patients with clinical signs of infection (G I) and asymptomatic patients (G2) and patients receiving central venous catheters for clinical monitoring (G3) were analyzed by semi-quantitative culture and scanning electron microscopy. The central venous catheters of G1 presented more positive cultures than those of G2 and G3 (81% vs 50% and 0%, respectively). However, biofilms were observed in all catheters used and 55% of them showed structures that suggested central venous catheters colonization by microorganisms. Approximately 53% of the catheter infections evolved with systemic infection confirmed by blood Culture. The authors conclude that the presence of a biofilm is frequent and is all indicator of predisposition to infection, which may even occur in patients who are still asymptomatic. (JPEN J Parenter Enteral Nutr. 2009;33:397-403)

Bacterial colonization in hemodialysis temporary dual lumen catheters: A prospective study

Aims. The use of hemodialysis temporary dual-lumen catheters is often complicated by infections, which may be a significant cause of death among patients with end stage renal disease (ESRD). The aim of this study was to assess the incidence of bacteremia and bacterial colonization related to non-tunneled, non-cuffed, dual-lumen temporary catheters in patients with ESRD submitted to hemodialysis. Methods. This study included 29 patients with ESRD. After catheter implantation, patients were monitored throughout the period of catheter permanence by means of blood samples collected weekly from a peripheral vein. Bacteria were isolated and identified according to CLSI recommendations. When catheters were removed for any reason, their tips were evaluated microbiologically. Results. A total of 194 blood samples from the 29 patients implanted with 55 catheters were analyzed. Of these, 15.5% (30 samples) demonstrated bacterial growth, principally Staphylococcus epidermidis (64.5%). Twenty patients (68.9%) presented at least one positive blood culture during follow-up. The median time for catheter colonization was 18.5 days (95% CI: 16.8-30.3). Of the 55 catheters implanted, 28 (50.9%) showed bacterial colonization, corresponding to 23.4 episodes/1000 catheter/days and 9.2 episodes of bacteremia /1000 catheter/days. Fifteen of 28 catheter tips analyzed showed bacterial growth (53.5%). In 14 of these (93.3%), there was agreement between the isolates from the catheter tip and blood cultures. Of 24 episodes of positive blood cultures from 20 different patients in 17 episodes (70.8%), the patients showed no clinical signs or symptoms of bacteremia. Conclusions. The high incidence of catheter colonization, the correlation between blood and catheter tip cultures, and the occurrence of frequent cases of asymptomatic bacteremia justify the proposal of routine peripheral blood collections to monitor patients undergoing hemodialysis with temporary dual-lumen catheters.

Arteriovenous Fistula Puncture: An Essential Factor for Hemodialysis Efficiency

Objective. To determine the blood recirculation ratio in the vascular access of patients on hemodialysis, and to calculate the Kt/Vs obtained with the different techniques of arteriovenous fistula punctures. Materials and Methods. A total of 174 patients were divided according to the technique used for arteriovenous fistula puncture: group 1, needles in opposite directions and with a distance of 5 cm or more between them; group 2, needles in opposite directions but with a distance of less than 5 cm; group 3, unidirectional needles with both directed to the heart and with a distance of 5 cm or more; group 4, unidirectional needles but separated by a distance of less than 5 cm between needles; and group 5, patients carrying a temporary venous catheter. Blood samples were collected for urea analysis, pre and post-dialysis for Kt/V rate, and other samples for calculation of the access recirculation. Results. Group 1 presented the lowest rate of access recirculation (8.51 +/- 4.90%) and the best Kt/V (1.71 +/- 0.36), while group 4 presented the worst access recirculation (20.68 +/- 4.92%) and Kt/V (1.16 +/- 0.26). All groups differed significantly from group 4 (p < 0.05), except group 5 with regard for Kt/V parameter. Discussion. The technique of arteriovenous fistula puncture is an essential factor to decrease the access recirculation and assure better results of measurement of hemodialysis adequacy. On the basis of the results obtained, insertion of the needles in the same direction and with a distance of less than 5 cm between them should be avoided.

Esophageal Contractions in Patients with Chronic Progressive External Ophthalmoplegia

Background Chronic progressive external ophthalmoplegia is a mitochondrial myopathy that causes muscular or multisystem symptoms and has dysphagia as one manifestation. Aim To evaluate esophageal contractions in patients with chronic progressive external ophthalmoplegia. Methods We studied 14 patients with chronic progressive external ophthalmoplegia and 16 asymptomatic volunteers. The diagnosis of the disease was established by the clinical picture and by mitochondrial DNA analysis in skeletal muscle. We used the manometric method with a perfusion catheter that recorded the esophageal contractions at 2, 7, 12, 17, and 22 cm from the lower esophageal sphincter (LES). All subjects performed in the supine position 20 swallows of a 5-ml bolus of water at room temperature, ten every 30 s and ten every 10 s. Results The amplitude, duration, and area under the curve of contractions at 17 and 22 cm from the LES were lower in patients than in volunteers for swallows performed at 10-s and 30-s intervals (P < 0.01). There was no difference in contractions at 7 and 2 cm, except for the contractions at 2 cm after swallows performed at 30-s intervals. The interval between the onset of contractions between 7 and 2 cm and between 22 and 2 cm was lower in patients than in volunteers, with swallows performed every 10 s and every 30 s. Conclusions There is impairment of esophageal contractions in patients with chronic progressive external ophthalmoplegia, mainly in the proximal esophageal body.

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia

There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries. Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1. HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO. Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility. British Journal of Pharmacology (2009) 157, 568-580; doi:10.1111/j.1476-5381.2009.00165.x; published online 9 April 2009 This article is part of a themed section on Endothelium in Pharmacology. For a list of all articles in this section see the end of this paper, or visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009.

Mechanisms underlying the biphasic effect of vitamin K-1 (phylloquinone) on arterial blood pressure

Phylloquinone (vitamin K-1, VK1) is widely used therapeutically and intravenous administration of this quinone can induce hypotension. We aimed to investigate the mechanisms underlying the effects induced by VK1 on arterial blood pressure. With this purpose a catheter was inserted into the abdominal aorta of male Wistar rats for blood pressure and heart rate recording. Bolus intravenous injection of VK1 (0.5-20 mg kg(-1)) produced a transient increase in blood pressure followed by a fall. Both the pressor and depressor response induced by VK1 were dose-dependent. On the other hand, intravenous injection of VK1 did not alter heart rate. The nitric oxide synthase (NOS) inhibitor N-G-nitro-L-arginine methyl ester (L-NAME, 10 and 20 mg kg(-1)) reduced both the increase and decrease in blood pressure induced by VK1 (5 mgkg(-1)). On the other hand, indometacin (10 mg kg(-1)), a non-selective cyclooxygenase inhibitor, did not alter the increase in mean arterial pressure (MAP) induced by VK1. However, VK1-induced fall in MAP was significantly attenuated by indometacin. We concluded that VK1 induces a dose-dependent effect on blood pressure that consists of an acute increase followed by a more sustained decrease in MAP. The hypotension induced by VK1 involves the activation of the nitric oxide (NO) pathway and the release of vasodilator prostanoid(s).

Sympathetic activity is not increased in L-NAME hypertensive rats

Santos FM, Dias DPM, Silva CAA, Fazan Jr R, Salgado HC. Sympathetic activity is not increased in L-NAME hypertensive rats. Am J Physiol Regul Integr Comp Physiol 298: R89-R95, 2010. First published November 4, 2009; doi:10.1152/ajpregu.00449.2009.-The role played by the sympathetic drive in the development of N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension is not firmly established. Therefore, the present study was undertaken in conscious rats in which hypertension was induced by treatment with L-NAME over the course of either 2 or 14 days. Mean arterial pressure (MAP) was measured via a catheter placed in the femoral artery, drugs were administered via a cannula placed in the femoral vein, and renal sympathetic nerve activity (RSNA) was monitored using an implanted electrode. Despite the remarkable increase in arterial pressure, heart rate did not change after treatment with L-NAME. RSNA was similar in L-NAME-induced hypertensive rats treated over the course of 2 or 14 days, as well as in normotensive rats. It was also demonstrated that L-NAME-induced hypertensive rats displayed a resetting of the baroreflex control of RSNA to hypertensive levels, with decreased sensitivity over the course of 2 or 14 days. Furthermore, the sympathetic-vagal balance examined in the time and frequency domain and the renal and plasma norepinephrine content did not differ between groups. In conclusion, the evaluation of the sympathetic drive in conscious rats demonstrated that the arterial hypertension induced by L-NAME treatment over the course of 2 and 14 days does not show sympathetic overactivity.

Water deprivation increases Fos expression in hypothalamic corticotropin-releasing factor neurons induced by right atrial distension in awake rats

Atrial mechanoreceptors, sensitive to stretch, contribute in regulating heart rate and intravascular volume. The information from those receptors reaches the nucleus tractus solitarius and then the paraventricular nucleus (PVN), known to have a crucial role in the regulation of cardiovascular function. Neurons in the PVN synthesize CRF, AVP, and oxytocin (OT). Stimulation of atrial mechanoreceptors was performed in awake rats implanted with a balloon at the junction of the superior vena cava and right atrium. Plasma ACTH, AVP, and OT concentrations and Fos, CRF, AVP, and OT immunolabeling in the PVN were determined after balloon inflation in hydrated and water-deprived rats. The distension of the balloon increased the plasma ACTH concentrations, which were higher in water-deprived than in hydrated rats (P < 0.05). In addition, the distension in the water-deprived group decreased plasma AVP concentrations (P < 0.05), compared with the respective control group. The distension increased the number of Fos- and double-labeled Fos/CRF neurons in the parvocellular PVN, which was higher in the water-deprived than in the hydrated group (P < 0.01). There was no difference in the Fos expression in magnocellular PVN neurons after distension in hydrated and water-deprived groups, compared with respective controls. In conclusion, parvocellular CRF neurons showed an increase of Fos expression induced by stimulation of right atrial mechanoreceptors, suggesting that CRF participates in the cardiovascular reflex adjustments elicited by volume loading. Activation of CRF neurons in the PVN by cardiovascular reflex is affected by osmotic stimulation.

A randomized trial of 5 versus 7 French guiding catheters for transfemoral percutaneous coronary stent implantation

Comparative studies between 5 French guiding catheter and others of larger size using the transfemoral approach to coronary stenting have not been described. Coronary stent implantation was performed in 90 patients in a randomized trial. The primary end-point was to compare the incidence of successful uncomplicated stent implantation per lesion with the 5F and 7F guiding catheters. Patients were excluded for excessive vessel tortuosity or anticipated need for equipment not fitting through a 5 catheter. Baseline characteristics and the use of direct stenting did not differ between the two groups. The primary success rate was 97.8% per patient in both groups and 98% per lesion in the 5 French and 97.9% in the 7 French. Guiding catheter change was necessary in 1 patient in each group to successfully complete the procedure in both groups. The amount of contrast used was 63 +/- 27.3 mL in the 5 French and 76 +/- 25 mL in the 7 French groups (P < 0.05). Vascular complications and blood transfusions occurred somewhat more frequently in the 7 French group (P = 0.058). The manual compression time after sheath removal was 5.1 +/- 2.0 min and 8.0 +/- 4.3 min, respectively, in the 5 and 7 French groups (P < 0.01). In conclusion, the 5 French guiding catheters showed a similar success rate with coronary stenting when compared to the 7 French, but the amount of contrast used and manual compression time after sheath removal, as well as the rate of vascular and bleeding complications, were reduced in the 5 French group.

Percutaneous Transatrial Access to the Pericardial Space for Epicardial Mapping and Ablation

Background-Puncture of the atrial appendage may provide access to the pericardial space. The aim of this study was to evaluate the feasibility of epicardial mapping and ablation through an endocardial transatrial access in a swine model. Methods and Results-An 8-F Mullins sheath was used to perforate the right (n=16) or left (n=1) atrial appendage in 17 pigs (median weight, 27.5 kg; first and third quartiles [Q1, Q3], 25.2, 30.0 kg). A 7-F ablation catheter was introduced into the pericardial space to perform epicardial mapping and deliver radiofrequency pulses on the atria. The pericardial space was entered in all 17 animals. In 15 (88%) animals, there was no hemodynamic instability (mean blood pressure monitoring, initial median, 80 mm Hg; Q1, Q3, 70, 86 mm Hg; final median, 88 mm Hg; Q1, Q3, 80, 96 mm Hg; P=0.426). In these 15, a mild hemorrhagic pericardial effusion was identified and aspirated (median, 20 mL; Q1, Q3, 15, 30 mL) during the procedure, and postmortem gross analysis revealed that the atrial perforation was closed in these animals. In 2 (12%) of the 17 animals, there was major pericardial bleeding with hemodynamic collapse. On gross examination, it was found that pericardial space was accessed through right ventricular perforation in 1 animal and the tricuspid annulus in the other. After the initial study, we used an occlusion device in 3 other animals to attempt to seal the puncture (2 at the right atrial appendage and 1 at the right ventricle). These 3 animals had no significant pericardial bleeding. Conclusions-Transatrial endovascular right atrial appendage puncture may provide a potential alternative route for pericardial access. Further studies are needed to evaluate its safety with longer and more-complex procedures before being applied in clinical settings. (Circ Arrhythm Electrophysiol. 2011;4:331-336.)