The Impact of Culturing the Organ Preservation Fluid on Solid Organ Transplantation: A Prospective Multicenter Cohort Study

Background

We analyzed the prevalence, etiology, and risk factors of culture-positive preservation fluid and their impact on the management of solid organ transplant recipients.

Methods

From July 2015 to March 2017, 622 episodes of adult solid organ transplants at 7 university hospitals in Spain were prospectively included in the study.

Results

The prevalence of culture-positive preservation fluid was 62.5% (389/622). Nevertheless, in only 25.2% (98/389) of the cases were the isolates considered "high risk" for pathogenicity. After applying a multivariate regression analysis, advanced donor age was the main associated factor for having culture-positive preservation fluid for high-risk microorganisms. Preemptive antibiotic therapy was given to 19.8% (77/389) of the cases. The incidence rate of preservation fluid-related infection was 1.3% (5 recipients); none of these patients had received preemptive therapy. Solid organ transplant (SOT) recipients with high-risk culture-positive preservation fluid receiving preemptive antibiotic therapy presented both a lower cumulative incidence of infection and a lower rate of acute rejection and graft loss compared with those who did not have high-risk culture-positive preservation fluid. After adjusting for age, sex, type of transplant, and prior graft rejection, preemptive antibiotic therapy remained a significant protective factor for 90-day infection.

Conclusions

The routine culture of preservation fluid may be considered a tool that provides information about the contamination of the transplanted organ. Preemptive therapy for SOT recipients with high-risk culture-positive preservation fluid may be useful to avoid preservation fluid-related infections and improve the outcomes of infection, graft loss, and graft rejection in transplant patients.

Improving the Outcomes of Organs Obtained From Controlled Donation After Circulatory Death Donors Using Abdominal Normothermic Regional Perfusion

The use of donation after circulatory death (DCD) has increased significantly during the past decade. However, warm ischemia results in a greater risk for transplantation. Indeed, controlled DCD (cDCD) was associated with inferior outcomes compared with donation after brain death. The use of abdominal normothermic regional perfusion (nRP) to restore blood flow before organ recovery in cDCD has been proposed as better than rapid recovery to reverse the effect of ischemia and improve recipients' outcome. Here, the first Spanish series using abdominal nRP as an in situ conditioning method is reported. A specific methodology to avoid restoring circulation to the brain after death determination is described. Twenty-seven cDCD donors underwent abdominal nRP during at least 60 min. Thirty-seven kidneys, 11 livers, six bilateral lungs, and one pancreas were transplanted. The 1-year death-censored kidney survival was 91%, and delayed graft function rate was 27%. The 1-year liver survival rate was 90.1% with no cases of ischemic cholangiopathy. Transplanted lungs and pancreas exhibited primary function. The use of nRP may represent an advance to increase the number and quality of grafts in cDCD. Poor results in cDCD livers could be reversed with nRP. Concerns about restoring brain circulation after death are easily solved.

[Primary graft dysfunction after lung transplantation]

Lung transplantation is a therapeutic option for pulmonary diseases in which the other treatment options have failed or in cases of rapid disease progression. However, transplantation is not free from complications, and primary graft dysfunction is one of them. Primary graft dysfunction is a form of acute lung injury. It characteristically develops during the immediate postoperative period, being associated to high morbidity and mortality, and increased risk of bronchiolitis obliterans. Different terms have been used in reference to primary graft dysfunction, leading to a consensus document to clarify the definition in 2005. This consensus document regards primary graft dysfunction as non-cardiogenic pulmonary edema developing within 72 hours of reperfusion and intrinsically attributable to alteration of the lung parenchyma. A number of studies have attempted to identify risk factors and to establish the underlying physiopathology, with a view to developing potential therapeutic options. Such options include nitric oxide and pulmonary surfactant together with supportive measures such as mechanical ventilation or oxygenation bypass.

[Brain abscess in a third-level hospital: epidemiology and prognostic factors related to mortality]

OBJECTIVE

To document the epidemiology, causes, treatment and prognostic factors associated with mortality of patients with brain abscess in a tertiary medical center.

METHODS

Observational retrospective cohort study of patients with cerebral abscess admitted at a tertiary hospital during 13 years.

RESULTS

The case records of 71 patients admitted to a tertiary hospital between January 1992 and December 2005 and diagnosed of brain abscess were review. Brain abscess occurred at all ages, more frequently in men than in women. Fever, headache and altered mental status were common presenting symptoms. The most common site of infection was the frontal lobe (28 patients). Seventeen patients had multiple abscesses. Staphylococcal infection was seen most commonly. Computed tomography provided sufficient diagnostic information in all cases. Twenty six patients had early surgical drainage. Thirty four patients were admitted to the intensive care Unit (ICU). The overall mortality was 21% (15 patients), all of that related to the infection. Six patients died in ICU. More than 65 years of age (OR, 1.0; CI 95%, 1.0-1.1), medical treatment without surgery (OR, 8.9; CI 95%, 1.1-73.8), presence of multiple abscesses, (OR, 6.0; CI 95%, 1.0-34.9), immunosuppression (OR, 21.5; CI 95%, 2.9-157.2) and delay in starting antibiotherapy (OR, 1.5 per day of delay; CI 95%, 1.0-2.1) were independent predictors of in-hospital death.

CONCLUSIONS

In spite of improvement in diagnosis and treatment of patients with cerebral abscess, mortality is still high. Factors related to patient underlying diseases and the delay in the start an antibiotic treatment were associated with increased mortality (50% increase of mortality risk per day in the delay of starting antibiotherapy).

Prognostic factors and outcome after drowning in an adult population

BACKGROUND

Drowning remains an actual problem. Although medical assistance has improved, it still has high rates of morbidity and mortality. We set out to explore the clinical characteristics and outcome of drowning patients admitted to the intensive care unit (ICU) of tertiary-care university hospital.

METHODS

We designed a retrospective observational study to analyse all drowning patients admitted to our ICU after successful cardiopulmonary resuscitation. The study was conducted during 1 January 1992-31 December 2005. There was no exclusion. We used a univariate analysis to evaluate the effect on patient and management characteristics on survival.

RESULTS

There were 43 patients (five children and 38 adults), with male predominance. Fifteen patients, all adults (34.9%), died. Submersion time, age, Glasgow Coma Score (GCS), pupillary reactivity and acute physiology and chronic health evaluation (APACHE II) at ICU admission were related to mortality. Non-survivors presented a higher glycaemia level at ICU admission than survivors (P=0.005).

CONCLUSIONS

The outcome is closely related to the patient's clinical status on arrival to the hospital. We have found that submersion time, age, GCS, pupillary reactivity and APACHE II at ICU admission were related to mortality. Further research in prospective studies is needed.

Taste aversion learning and aging: a comparison with the effect of dorsal hippocampal lesions in rats

The relationship between hippocampal function and aging was explored in Wistar rats using taste aversion learning by comparing the performance of adult dorsal hippocampal lesioned and fifteen-month-old intact rats with that of adult intact rats. In experiment 1 the conditioned blocking phenomenon was absent in the hippocampal and the aging rats. Unlike the adult intact rats, the hippocampal and aging rats were not impaired in acquiring a learned aversion to a cider vinegar solution (3 %) presented as a serial compound with a previously conditioned saccharin solution (0.1 %). In experiment 2 both the hippocampal and the aging rats developed reduced aversions to a saline solution (0.5 %) followed by an i.p. injection of lithium chloride (0.15 M; 2 % b.w.) if the taste solution was previously preexposed without consequences. This latent inhibition effect was similar to that seen in intact adult rats. In both experiments, the aging rats exhibited enhanced conventional learned taste aversions. It is concluded that aging is not a unitary process but induces both hippocampal dependent and hippocampal independent complex changes in the functioning of the neural circuits, implementing taste aversion learning.

Development of a simple and sensitive technique for detection of point mutations in the K-ras oncogene

We sought to develop a simple and sensitive method based on mutant allele-specific amplification (MASA) for the detection of point mutations in the k-ras oncogene in blood samples. We used MASA and three nested MASA methods to detect a point mutation (GGT-->GAT) in rat DHD cells at codon 12 of exon 1 of the k-ras gene. MASA allowed us to detect one k-ras mutated cell on a background of 10(7) normal cells. The third nested-MASA (nested-MASA.c) method that we developed allowed us to detect one mutated cell among 10(10) normal cells. Our methods should allow the detection of small amounts of mutant k-ras DNA in tissue, serum, and plasma, combining speed with efficiency and specificity.

Differential effects of bicuculline and muscimol microinjections into the nucleus basalis magnocellularis in taste and place aversive memory formation

The role of the nucleus basalis magnocellularis (NBM) in learning and memory has been demonstrated in different learning paradigms such as conditioned taste aversion (CTA) and inhibitory avoidance (IA). This participation has been related to the cholinergic system, but recent studies have reported the potential role of other neurotransmitters such as GABA. The effects of acute intracerebral administration of the GABAergic antagonist bicuculline (0.05 microg) and the GABAergic agonist muscimol (0.05 microg) into the NBM of male Wistar rats were assessed in CTA and IA learning. In both learning tasks, the drug administration was performed before the acquisition. Taste aversion learning was not affected by the infusion of any of the drugs administered. IA acquisition was not affected by the administration of bicuculline or muscimol, requiring similar number of trials to reach the learning criterion. However, when the rats were tested 24 h later, those injected with bicuculline or muscimol showed an impairment of the IA learning. The present results support a role of the GABAergic system in the consolidation process of IA learning.

Dissociation of the associative and visceral sensory components of taste aversion learning by tetrodotoxin inactivation of the parabrachial nucleus in rats

The parabrachial nucleus (PBN) has been proposed as the associative site for conditioned taste aversion. Previous evidence has shown that functional blockade of the PBN by tetrodotoxin (TTX) produces retrograde disruption of lithium-induced taste aversions in rats. However, given the PBN role in processing visceral cues and the long duration of the lithium-induced aversive effects, an interpretation based on lithium chloride processing deficits can not be ruled out. The aim of the present study was to use the unconditioned stimulus (US) pre-exposure phenomenon to explore the effect of PBN inactivation by intracerebral TTX microinjections on visceral processing. Three intraperitoneal (i.p.) lithium chloride injections (0.15 M; 2% b.w.) applied before the conditioning session, but not isotonic saline i.p. injections, interfered with the acquisition of a learned aversion to a cider vinegar solution (3%) in cannulated control rats. Bilateral PBN inactivation by TTX (10 ng) applied immediately after each LiCl injections disrupted the US pre-exposure effect, thus confirming its sensory role. However, PBN inactivation 30 min after LiCl injections did not interfere with the US pre-exposure effect, in spite of the fact that an identically timed PBN blockade after the acquisition trial disrupted the acquisition of taste aversions. These results stand for the associative role of PBN in taste aversion learning induced by lithium chloride, independent of its sensory role. It is concluded that PBN activity is required after the conditioning trial for the taste-visceral association to take place.

Conditioned blocking is re-established by neurotransplantation in mature rats

Aging has been associated with a decay of hippocampal function that may begin well before senescence. Conditioned blocking is a complex learning phenomenon that requires an intact hippocampus in young-adult rats and is absent in middle-aged rats. The aim of the present study was to test the possibility of re-establishing conditioned blocking in 17-month-old Wistar rats by neurotransplantation. Solid embryonic hippocampal or nigral tissue was bilaterally transplanted in the proximity of the dorsal hippocampus (lateral ventricle and alveus). Conditioned blocking of an aversion to a cider vinegar (3%) solution presented in compound with a previously conditioned saccharin solution (0.1%) appeared 14 days after transplantation and persisted 3 months later only in the hippocampal grafted group, showing the possibility of restoring age-related cognitive deficits.

Bilateral tetrodotoxin blockade of the rat vestibular nuclei substitutes the natural unconditioned stimulus in taste aversion learning

The aversive effects of bilateral transient blockade of the lateral vestibular nucleus caused by tetrodotoxin microinjections were tested using conditioned taste aversion in the first experiment. Male Wistar rats received tetrodotoxin injections (10 ng) after drinking a coffee solution (0.5%), either in the lateral vestibular nucleus (LVN), the parabrachial nucleus or the dopaminergic area A8. Two days later they drank a cider vinegar solution (3%) not followed by injections. In a later choice test, only the group receiving the injection in the lateral vestibular nucleus displayed a coffee aversion. In a second experiment the role of the peripheral vestibular symptoms induced by LVN inactivation on substituting the aversive stimulus was explored in the same behavioral task. Rats anesthetized (Pentobarbital, 25 mg/kg) before tetrodoxin LVN blockade, that did not show peripheral symptoms, did not develop learned aversions. The coffee preference ratios did not differ to those animals receiving only anesthesia or those that remained undisturbed. These results showed that the bilateral blockade of the vestibular nuclei may induce peripheral vestibular symptoms that that may substitute the aversive stimulus in taste aversion learning.

Functional blockade of the parabrachial area by tetrodotoxin disrupts the acquisition of conditioned taste aversion induced by motion-sickness in rats

The role of the parabrachial area in conditioned taste aversion (CTA) induced by motion-sickness was studied in male Wistar rats. In the first experiment, one-trial conditioned taste aversion, to a 0.5% decaffeinated coffee solution, was induced by 30 min of vertical rotatory motion (80 rev./min) in intact rats. In the second experiment, reversible blockade of the neural activity in various brainstem sites was induced by bilateral intracerebral injections of tetrodotoxin (TTX) (10 ng/microl) after conditioning. Blockade of the parabrachial area, but neither A8 nor lateral vestibular nucleus, disrupted the acquisition of (CTA). The results are discussed in terms of an associative role of the parabrachial area in body rotation-induced taste aversion learning, as the area was intact during sensory processing and testing.

Measurement of gastric bicarbonate secretion in the human stomach: different methods produce discordant results

Human gastric bicarbonate secretion has been measured by back-titration, from pH and pressure of carbon dioxide (PCO2) determinations (using the Henderson-Hasselbalch formula), and from equations based on gastric juice osmolality and [H+] (osmolality-[H+] method). Since these methods show large quantitative differences in their estimations of gastric bicarbonate secretion, we examined each to define the reasons for these discrepancies and establish guidelines for future work in this area. Bicarbonate recovery from 'non-parietal' secretions (0 to 80 mM HCO3) reacting with 'pure parietal secretion' (160 mM HCl) was studied both in vitro and in the pylorus-occluded healthy human stomach during acid suppression, exogenous acidification, and pentagastrin stimulation. The pH/PCO2 method estimated HCO3- accurately under anaerobic conditions in vitro, whereas the osmolality-[H+] method (with correction factors for osmolality incorporated by us) was accurate under aerobic conditions. In the acid-suppressed stomach back-titration was significantly more accurate than the pH/PCO2 method. In the exogenously acidified and pentagastrin-stimulated stomachs the pH/PCO2 method underestimated bicarbonates, and the osmolality-[H+] method was spuriously elevated in the low range and diminished at high bicarbonate concentrations. Estimates of 'basal' bicarbonate secretion (at zero added bicarbonate) were severalfold higher by the osmolality-[H+] method (5.26 +/- 0.33 mmol/h) than by the pH/PCO2 method (1.20 +/- 0.23 mmol/h) or back-titration (0.65 +/- 0.14 mmol/h). In conclusion, gastric bicarbonate was determined most correctly by back-titration in the acid-suppressed stomach, whereas measurement of bicarbonate in the acid-secreting stomach was not accurate with any method.

Cholinergic regulation of human proximal duodenal mucosal bicarbonate secretion

Cephalic-vagal stimulation affects a number of upper gastrointestinal secretory and motility events. The purpose of this study was to examine the role of vagal-cholinergic regulation on human proximal duodenal mucosal HCO-3 secretion. The duodenal bulb was isolated between balloons and perfused with 154 mM NaCl, and HCO-3 secretion was measured. Although cholinergic stimulation with bethanechol (50 micrograms.kg-1.h-1 iv) produced systemic effects, resting HCO-3 secretion was unchanged. Cephalic-vagal stimulation, induced by sham feeding, significantly increased duodenal HCO-3 secretion from a basal of 177 +/- 17 to 240 +/- 19 mumols.cm-1.h-1 (P less than 0.02). The response to sham feeding was approximately 50% of the peak response to acid-stimulated HCO-3 output. Atropine (22 micrograms/kg iv) inhibited basal HCO-3 secretion significantly (79 +/- 5%). However, the net incremental increases in duodenal mucosal HCO-3 secretion in response to luminal acidification and vagal stimulation were unaltered by atropine pretreatment. Additionally, indomethacin (100 mg po) failed to modify the response to vagal-stimulated HCO-3 secretion. These findings indicate that basal human proximal duodenal mucosal HCO-3 secretion is maintained largely by resting cholinergic innervation and is stimulated by cephalic-vagal stimulation. Furthermore, since the incremental HCO-3 responses to cephalic-vagal stimulation and luminal acidification were unaltered by atropine pretreatment, each is likely mediated by noncholinergic mechanisms.

Human duodenal mucosal bicarbonate secretion. Evidence suggesting active transport under basal and stimulated conditions

When the proximal duodenum of animals or humans is perfused with isoosmolar NaCl, bicarbonate enters the luminal effluent. In addition, duodenal bicarbonate output is stimulated by luminal acidification and prostaglandins of the E class. The hypothesis that in vivo human duodenal bicarbonate transport persists in the absence of a plasma-to-lumen bicarbonate gradient and therefore is probably an active transport process was tested. In healthy subjects, a 4-cm segment of the proximal duodenum was isolated from gastric and pancreaticobillary secretions. Net duodenal bicarbonate secretion remained similar to basal levels during luminal perfusion with either 24 or 32 mM bicarbonate (each isoosmolar with plasma by the addition of NaCl). In addition, peak increases in acid-induced bicarbonate outputs with luminal perfusion of 154 mM NaCl and 32 mM NaHCO3 (+122 mM NaCl) were similar. Moreover, prostaglandin E2-stimulated bicarbonate secretion with perfusion of 154 mM NaCl and 32 mM NaHCO3 (+122 mM NaCl) was similar. It was concluded that in humans, proximal duodenal mucosal bicarbonate transport remains unaltered in the absence of a plasma-to-lumen bicarbonate gradient at rest and after stimulation with HCl or prostaglandin E2. These observations suggest that human proximal duodenal bicarbonate secretion involves active transport.

Bolus or intravenous infusion of ranitidine: effects on gastric pH and acid secretion. A comparison of relative efficacy and cost

STUDY OBJECTIVE

To compare the effects of intravenous bolus injection of ranitidine, continuous intravenous infusion of ranitidine, and placebo on gastric pH, acid secretion, and plasma ranitidine concentration during a 24-hour period, and to determine by survey the use, delivery methods, and costs of histamine H2-receptor antagonists in intensive care units.

DESIGN

Double-blind, Latin-square randomized, prospective measurement of the gastric pH, acid output, and plasma ranitidine concentration over 24 hours in response to six treatment regimens in 12 patients with inactive duodenal ulcer. Eight regional hospitals were surveyed to obtain information on the use of histamine H2-receptor antagonists.

INTERVENTIONS

Gastric acid secretion, pH, and plasma ranitidine were monitored for 24 hours on six separate days in response to placebo, intravenous bolus injection of ranitidine (50 mg every 8 hours and 75 mg every 12 hours), and continuous intravenous infusion of ranitidine (75, 150, and 300 mg every 24 hours).

MEASUREMENTS AND MAIN RESULTS

Intravenous infusions were significantly more effective than bolus injections. After bolus injections, hourly gastric pH values fluctuated widely, from 7.6 to 1.6, whereas during continuous infusion of 150 mg and 300 mg, hourly pH values were 3.8 or greater. The gastric pH was greater than 4.0 in 75% +/- 5% and 83% +/- 6% of determinations done during continuous intravenous infusion of 150 mg and 300 mg, respectively. Fluctuations in the plasma ranitidine concentration corresponded with changes in gastric pH and acid secretion. Histamine H2-receptor antagonists were prescribed for about 75% of patients in intensive care units and were most commonly administered by bolus rather than infusion (5:1); the cost was approximately +40 per day less by infusion.

CONCLUSIONS

On the basis of both efficacy and cost, intermittent bolus injections should be discontinued and replaced by continuous intravenous infusion in hospitalized patients requiring treatment with histamine H2-receptor antagonists. If ranitidine is used, either 150 mg or 300 mg administered as a 24-hour continuous infusion is most effective.

Cyclooxygenase inhibition with indomethacin increases human duodenal mucosal response to prostaglandin E1

In humans, prostaglandins of the E1 class stimulate duodenal mucosal bicarbonate secretion, whereas the cyclooxygenase inhibitor, indomethacin, decreases both mucosal PGE2 and bicarbonate production. The purpose of this study was to determine whether a synthetic prostaglandin E1, enisoprost, diminished the inhibitory effects of indomethacin on mucosal bicarbonate secretion. In seven healthy subjects the proximal 4 cm of duodenum was isolated by occluding balloons. The isolated test segment was perfused with 154 mM NaCl (2 ml/min, 37 degrees C). Each subject participated in four separate tests in random order. Indomethacin, 50 mg, or placebo was given 13 and 1 hr before testing. After measuring basal bicarbonate secretion, either 100 micrograms of prostaglandin E1 or placebo (in 154 mM NaCl) was perfused into the test segment over 30 min. As anticipated, PGE1 significantly increased duodenal mucosal bicarbonate secretion, and indomethacin decreased resting bicarbonate secretion. Indomethacin pretreatment significantly enhanced (P less than 0.03) the mucosa's response to PGE1 compared to PGE1 alone. These results further support the observations that endogenous prostaglandins, in part, regulate human proximal duodenal bicarbonate secretion. Furthermore, suppression of endogenous prostaglandin generation results in an increased sensitivity of the duodenal mucosa to PGE1.