Mechanisms of the systemic inflammatory response

Physiological strategies in wild rodents: immune defenses of commensal rats

The importance of issues associated with urban/commensal rats and mice (property damage, management costs, and health risks) press upon research on these animals. While the demography of commensal rodents is mostly studied, the need for understanding factors influencing their natural morbidity/mortality is also stressed. In this respect, more attention is expected to be paid to immunity, the physiological mechanism of defense against host survival threats (pathogens, parasites, diseases). Commensal rats and mice carry numerous pathogens that evoke diverse immune responses. The state of immunity in commensal house mice is studied in great detail, owing to the use of laboratory strains in biomedical research. Because commensal rats are, compared to mice, carriers of more zoonotic agents, rats' immunity is studied mainly in that context. Some of these zoonotic agents cause chronic, asymptomatic infections, which justified studies of immunological mechanisms of pathogen tolerance versus clearance regulation in rats. Occurrence of some infections in specific tissues/organs pressed upon analysis of local/regional immune responses and/or immunopathology. A survey of immunological activity/responses in commensal rats is given in this review, with mention of existing data in commensal mice. It should throw some light on the factors relevant to their morbidity and lifespan, supplementing the knowledge of commensal rodent ecology.

Development of Biotinylated Liposomes Encapsulating Metformin for Therapeutic Targeting of Inflammation-Based Diseases

Inflammation is a physiological response to a damaging stimulus but sometimes can be the cause of the onset of neurodegenerative diseases, atherosclerosis, and cancer. These pathologies are characterized by the overexpression of inflammatory markers like endothelial adhesion molecules, such as Vascular Cell Adhesion Molecule-1 (VCAM-1). In the present work, the development of liposomes for therapeutic targeted delivery to inflamed endothelia is described. The idea is to exploit a three-step pretargeting system based on the biotin-avidin high-affinity interaction: the first step involves a previously described biotin derivative bearing a VCAM-1 binding peptide; in the second step, the avidin derivative NeutrAvidinTM, which strongly binds to the biotin moiety, is injected; the final step is the administration of biotinylated liposomes that would bind to NeutravidinTM immobilized onto VCAM-1 overexpressing endothelium. Stealth biotinylated liposomes, prepared via the thin film hydration method followed by extrusion and purification via size exclusion chromatography, have been thoroughly characterized for their chemico-physical and morphological features and loaded with metformin hydrochloride, a potential anti-inflammatory agent. The three-step system, tested in vitro on different cell lines via confocal microscopy, FACS analysis and metformin uptake, has proved its suitability for therapeutic applications.

Effects of inflammation and oxidative stress on postoperative delirium in cardiac surgery

The past decade has witnessed unprecedented medical progress, which has translated into cardiac surgery being increasingly common and safe. However, complications such as postoperative delirium remain a major concern. Although the pathophysiological changes of delirium after cardiac surgery remain poorly understood, it is widely thought that inflammation and oxidative stress may be potential triggers of delirium. The development of delirium following cardiac surgery is associated with perioperative risk factors. Multiple interventions are being explored to prevent and treat delirium. Therefore, research on the potential role of biomarkers in delirium as well as identification of perioperative risk factors and pharmacological interventions are necessary to mitigate the development of delirium.

Impact of Systemic Inflammatory Response Syndrome on Clinical, Echocardiographic, and Computed Tomographic Outcomes Among Patients Undergoing Transcatheter Aortic Valve Implantation

Background

Systemic inflammatory response syndrome (SIRS) is a systemic insult that has been described with many interventional cardiac procedures. The outcomes of patients undergoing transcatheter aortic valve implantation (TAVI) are thought to be influenced by this syndrome not only on short-term, but also on long-term.

Objective

We assessed the association of SIRS to different clinical, echocardiographic, and computed tomographic (CT) outcomes after TAVI.

Methods

Two hundred and twenty-four consecutive patients undergoing TAVI were enrolled in this study. They were assessed for the occurrence of SIRS within the first 48 h after TAVI. Patients were followed-up for short- and long-term clinical outcomes. Serial echocardiographic follow-ups were conducted at 1-week, 6-months, and 1-year. CT follow-up at 1 year was recorded.

Results

Eighty patients (36%) developed SIRS. Among different parameters, only pre-TAVI total leucocytic count (TLC), pre-TAVI heart rate, and post-TAVI systolic blood pressure independently predicted the occurrence of SIRS. The incidence of HALT was not significantly different between both groups, albeit higher among SIRS patients (p = 0.1) at 1-year CT follow-up. Both groups had similar patterns of LV recovery on serial echocardiography. Long-term follow-up showed that all-cause death, cardiac death, and re-admission for heart failure (HF) or acute coronary syndrome (ACS) were significantly more frequent among SIRS patients. Early safety and clinical efficacy outcomes were more frequently encountered in the SIRS group, while device-related events and time-related valve safety were comparable.

Conclusion

Although SIRS implies an early acute inflammatory status post-TAVI, yet its clinical sequelae seem to extend to long-term clinical outcomes.

Potentials of Neuropeptides as Therapeutic Agents for Neurological Diseases

Despite recent leaps in modern medicine, progress in the treatment of neurological diseases remains slow. The near impermeable blood-brain barrier (BBB) that prevents the entry of therapeutics into the brain, and the complexity of neurological processes, limits the specificity of potential therapeutics. Moreover, a lack of etiological understanding and the irreversible nature of neurological conditions have resulted in low tolerability and high failure rates towards existing small molecule-based treatments. Neuropeptides, which are small proteinaceous molecules produced by the body, either in the nervous system or the peripheral organs, modulate neurological function. Although peptide-based therapeutics originated from the treatment of metabolic diseases in the 1920s, the adoption and development of peptide drugs for neurological conditions are relatively recent. In this review, we examine the natural roles of neuropeptides in the modulation of neurological function and the development of neurological disorders. Furthermore, we highlight the potential of these proteinaceous molecules in filling gaps in current therapeutics.

A Systematic Review and Meta-Analysis Examining the Impact of Sleep Disturbance on Postoperative Delirium

OBJECTIVES

Basic science and clinical studies suggest that sleep disturbance may be a modifiable risk factor for postoperative delirium. We aimed to assess the association between preoperative sleep disturbance and postoperative delirium.

DATA SOURCES

We searched PubMed, Embase, CINAHL, Web of Science, and Cochrane from inception until May 31, 2017.

STUDY SELECTION

We performed a systematic search of the literature for all studies that reported on sleep disruption and postoperative delirium excluding cross-sectional studies, case reports, and studies not reported in English language.

DATA EXTRACTION

Two authors independently performed study selection and data extraction. We calculated pooled effects estimates with a random-effects model constructed in Stata and evaluated the risk of bias by formal testing (Stata Corp V.14, College Station, TX), DATA SYNTHESIS:: We included 12 studies, from 1,238 citations that met our inclusion criteria. The pooled odds ratio for the association between sleep disturbance and postoperative delirium was 5.24 (95% CI, 3.61-7.60; p < 0.001 and I = 0.0%; p = 0.76). The pooled risk ratio for the association between sleep disturbance and postoperative delirium in prospective studies (n = 6) was 2.90 (95% CI, 2.28-3.69; p < 0.001 and I = 0.0%; p = 0.89). The odds ratio associated with obstructive sleep apnea and unspecified types of sleep disorder were 4.75 (95% CI, 2.65-8.54; p < 0.001 and I = 0.0%; p = 0.85) and 5.60 (95% CI, 3.46-9.07; p < 0.001 and I = 0.0%; p = 0.41), respectively. We performed Begg's and Egger's tests for publication bias and confirmed a null result for publication bias (p = 0.371 and 0.103, respectively).

CONCLUSIONS

Preexisting sleep disturbances are likely associated with postoperative delirium. Whether system-level initiatives targeting patients with preoperative sleep disturbance may help reduce the prevalence, morbidity, and healthcare costs associated with postoperative delirium remains to be determined.

Minimizing ICU Neurological Dysfunction with Dexmedetomidine-induced Sleep (MINDDS): protocol for a randomised, double-blind, parallel-arm, placebo-controlled trial

INTRODUCTION

Delirium, which is prevalent in postcardiac surgical patients, is an acute brain dysfunction characterised by disturbances in attention, awareness and cognition not explained by a pre-existing neurocognitive disorder. The pathophysiology of delirium remains poorly understood. However, basic science and clinical studies suggest that sleep disturbance may be a modifiable risk factor for the development of delirium. Dexmedetomidine is a α-2A adrenergic receptor agonist medication that patterns the activity of various arousal nuclei similar to sleep. A single night-time loading dose of dexmedetomidine promotes non-rapid eye movement sleep stages N2 and N3 sleep. This trial hypothesises dexmedetomidine-induced sleep as pre-emptive therapy for postoperative delirium.

METHODS AND ANALYSIS

The MINDDS (Minimizing ICU Neurological Dysfunction with Dexmedetomidine-induced Sleep) trial is a 370-patient block-randomised, placebo-controlled, double-blinded, single-site, parallel-arm superiority trial. Patients over 60 years old, undergoing cardiac surgery with planned cardiopulmonary bypass, will be randomised to receive a sleep-inducing dose of dexmedetomidine or placebo. The primary outcome is the incidence of delirium on postoperative day 1, assessed with the Confusion Assessment Method by staff blinded to the treatment assignment. To ensure that the study is appropriately powered for the primary outcome measure, patients will be recruited and randomised into the study until 370 patients receive the study intervention on postoperative day 0. Secondary outcomes will be evaluated by in-person assessments and medical record review for in-hospital end points, and by telephone interview for 30-day, 90-day and 180-day end points. All trial outcomes will be evaluated using an intention-to-treat analysis plan. Hypothesis testing will be performed using a two-sided significance level (type I error) of α=0.05. Sensitivity analyses using the actual treatment received will be performed and compared with the intention-to-treat analysis results. Additional sensitivity analyses will assess the potential impact of missing data due to loss of follow-up.

ETHICS AND DISSEMINATION

The Partners Human Research Committee approved the MINDDS trial. Recruitment began in March 2017. Dissemination plans include presentations at scientific conferences, scientific publications and popular media.

TRIAL REGISTRATION NUMBER

NCT02856594.

Systemic inflammatory response syndromes in the era of interventional cardiology

Systemic inflammatory response syndrome (SIRS), initially reported after cardiovascular surgery, has been described after various interventional cardiology procedures, including endovascular/thoracic aortic repair (EVAR/TEVAR), implantation of heart rhythm devices, percutaneous coronary intervention (PCI), electrophysiology procedures (EP), and transcatheter aortic valve implantation (TAVI). In these settings, a comprehensive understanding of the triggers, pathogenesis as well as a common diagnostic/therapeutic algorithm is lacking and will be discussed in this review. SIRS occurs in about 40% and 50% of patients undergoing TEVAR/EVAR and TAVI respectively; it affects 0.1% of patients undergoing implantation of heart rhythm devices. Prevalence is unknown after PCI or EP. Clinical presentation includes fever, dyspnoea/tachypnoea, tachycardia, weakness, chest pain and pericardial/pleural effusion. Several triggers can be identified, related to implanted devices, biomaterial, and procedural aspects (prolonged hypotension, aneurysm thrombus manipulation, active fixation atrial leads, coronary microembolization, balloon dilatation/stent implantantation, contrast medium, coronary/myocardial microperforation). Nonetheless, these triggers share three main pathogenic pathways leading to SIRS clinical manifestations: leucocytes activation, endothelial injury/activation, and myocardial/pericardial injury. Therapy consists of non-steroidal agents, with corticosteroids as second-line treatment in non-responders. Although a benign evolution is reported after implantation of heart rhythm devices, PCI and EP, major adverse events may occur after EVAR/TEVAR and TAVI at short- and mid-term follow up.

Spatiotemporal Dynamics of Dexmedetomidine-Induced Electroencephalogram Oscillations

An improved understanding of the neural correlates of altered arousal states is fundamental for precise brain state targeting in clinical settings. More specifically, electroencephalogram recordings are now increasingly being used to relate drug-specific oscillatory dynamics to clinically desired altered arousal states. Dexmedetomidine is an anesthetic adjunct typically administered in operating rooms and intensive care units to produce and maintain a sedative brain state. However, a high-density electroencephalogram characterization of the neural correlates of the dexmedetomidine-induced altered arousal state has not been previously accomplished. Therefore, we administered dexmedetomidine (1mcg/kg bolus over 10 minutes, followed by 0.7mcg/kg/hr over 50 minutes) and recorded high-density electroencephalogram signals in healthy volunteers, 18–36 years old (n = 8). We analyzed the data with multitaper spectral and global coherence methods. We found that dexmedetomidine was associated with increased slow-delta oscillations across the entire scalp, increased theta oscillations in occipital regions, increased spindle oscillations in frontal regions, and decreased beta oscillations across the entire scalp. The theta and spindle oscillations were globally coherent. During recovery from this state, these electroencephalogram signatures reverted towards baseline signatures. We report that dexmedetomidine-induced electroencephalogram signatures more closely approximate the human sleep onset process than previously appreciated. We suggest that these signatures may be targeted by real time visualization of the electroencephalogram or spectrogram in clinical settings. Additionally, these signatures may aid the development of control systems for principled neurophysiological based brain-state targeting.

Efficacy of leukocyte depletion of residual pump blood

In this study, we examined whether leukocyte depletion from the residual heart-lung machine blood at the end of cardiopulmonary bypass (CPB) has an effect on the leukocyte counts in the systemic circulation.

Twenty-six patients undergoing coronary artery bypass grafting (CABG) were randomly allocated to a leukocyte-depletion group or a control group. In the leukocyte-depletion group ( n = 13), all residual blood (400 mL to 1.4 L) was filtered by leukocyte-removal filters (Pall RS01) and reinfused to the patient after CPB, whereas, in the control group, an identical amount of residual blood after bypass was reinfused without filtration ( n = 13). Leukocyte-depleted allogeneic blood was transfused if needed.

Preoperative risk profiles, pump support and duration of aortic crossclamping time were identical in both patient groups (ns). Leukocyte depletion removed more than 96% of leukocytes from the residual retransfused blood ( p < 0.01) and significantly reduced circulating leukocytes ( p < 0.05) compared with the control group. Remarkably, lower numbers of circulating leukocytes were found, not at 1 hour after reinfusion, but at 4 and 8 hours after reinfusion ( p < 0.05). There were no statistical differences between the two groups with respect to postoperative blood loss, the number of transfused packed red cells and mechanical ventilation time.

These results show that leukocytes can be removed from the residual blood of the heart-lung machine after CPB very effectively. Furthermore, this leukocyte depletion results in a long-term effect, the clinical significance of which has to be elucidated in ongoing studies.

The potential of the novel leukocyte removal filter in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is indispensable for cardiac surgery but leads to systemic inflammatory responses and leukocyte activation, possibly due to blood contact with the surface of the CPB unit, surgical, ischemic reperfusion injury, etc. Systemic inflammatory responses during CPB result in increased morbidity and mortality. Activation of leukocytes is an important part of this process and directly contributes to coagulopathy and hemorrhage. This inflammatory response may contribute to the development of postoperative complications, including myocardial dysfunction, respiratory failure, renal and neurologic dysfunction, altered liver function and ultimately, multiple organ failure. Various pharmacologic and mechanical strategies have been developed to minimize the systemic inflammatory response during CPB. For example, leukocyte removal filters were developed in the 1990s for incorporation into the CPB circuit. However, studies of this approach have yielded conflicting findings. The purpose of this was to review the studies of a novel leukocyte removal filter in patients undergoing CPB.

Effects of different blood purification methods on serum cytokine levels and prognosis in patients with acute severe organophosphorus pesticide poisoning

The aim of the present study was to investigate the impact of three different blood purification methods, hemoperfusion (HP), continuous blood purification (CBP), and on-line high-volume hemodiafiltration (OL-HDF), on the survival rate of patients with acute severe organophosphorus pesticide poisoning (ASOPP), as well as on major pro-inflammatory (interleukin [IL]-1, IL-6, tumor necrosis factor-α [TNF-α]) and anti-inflammatory (IL-10) cytokines in the serum. Eighty-one ASOPP patients were randomly divided into three groups: HP (N = 23), HP + CBP (N = 26), HP + OL-HD (N = 32). Serum IL-1, IL-6, TNF-α, and IL-10 levels were assessed by ELISA before treatment and at 24 and 48 h post-treatment and survival rates were determined. Patient survival rate was significantly higher in OL-HDF and CBP treated patients compared with HP group (P < 0.05). A significantly greater clearance effect in serum IL-1, IL-6, and TNF-α levels at 24 and 48 h post-treatment was observed in CBP and OL-HDF groups compared with the HP group (P < 0.05). The levels of serum anti-inflammatory cytokine IL-10 increased significantly in CBP and OL-HDF groups compared with the HP group (P < 0.05 at 48 h post-treatment). In addition, OL-HDF treatment achieved similar changes in serum TNF-α, IL-1, IL-6 and IL-10 levels as CBP (P > 0.05). Compared with the HP method, CBP or OL-HDF combined with HP can rapidly clear inflammatory cytokines, reduce systemic inflammatory response syndrome, and improve the survival of ASOPP patients. Compared with CBP, OL-HDF is an economical and effective method to treat ASOPP with less technical difficulty and more suitability for rural areas and primary hospitals.

The effect of cardiopulmonary bypass and hypothermic circulatory arrest on hepatic histology in newborn animals: an experimental study

Still little is known about the effect of cardiac surgery on neonatal hepatic tissue. We examined the effect of cardiopulmonary bypass (CPB) and the effect of deep hypothermic circulatory arrest (DHCA) on neonatal hepatic tissue. Liver biopsies of neonatal piglets were taken after CPB (n = 4), after DHCA (n = 5), and after surgery without CPB (non-CPB; n = 3). Additionally, findings were compared to those of control piglets (n = 9). The liver specimens were fixed, stained with hematoxylin and eosin, and scored regarding inflammatory reaction, hepatocellular edema, and apoptosis. Inflammation score of treated groups was higher than in control; CPB 2.5 ± 0.5, DHCA 1.6 ± 0.4, non-CPB 1.2 ± 0.6, control 0.4 ± 0.3 (P < 0.001 CPB and DHCA vs. control; P < 0.05 non-CPB vs. control). Hepatic cell edema was more evident after DHCA (score 2.0 ± 0.4 vs. 0.2 ± 0.3 in control and 0.6 ± 0.5 after CPB; P < 0.001 and P < 0.05, respectively). The highest apoptotic cell count was in the non-CPB group (22.3 ± 6.3 vs. 11.4 ± 3.6 in control and 8.9 ± 5.4 after CPB; P < 0.05). The present study showed that (i) surgical trauma induces hepatic cell apoptosis; (ii) CPB increases hepatic inflammatory reaction; and (iii) DHCA amplifies hepatic cell edema.

Ulinastatin as a neuroprotective and anti-inflammatory agent in infant piglets model undergoing surgery on hypothermic low-flow cardiopulmonary bypass

OBJECTIVE

Infants are potentially more susceptible to brain injury mediated via cell death attributed to cardiopulmonary bypass (CPB) especially with prolonged hypothermic low flow (HLF). We hypothesized that a human urinary protease inhibitor (ulinastatin), by its anti-inflammatory effect, would reduce central nervous system (CNS) injury during HLF.

METHODS

Fifteen general-type infant piglets were randomized to ulinastatin group (group U, n = 5), control group (group C, n = 5), and sham operation group (group S, n = 5). Routine CPB was established after median thoracotomy in group U and C under anesthesia. When the temperature of infant piglets dropped down to 25 °C, low-flow CPB (50 ml·kg(-1) ·min(-1) ) was instituted. After 120 min of aortic cross-clamping and 20- to 30-min rewarming, the aortic cross-clamp was removed and finally the piglet was weaned from CPB. Five thousand units per killogram of ulinastatin and equivalently normal saline were, respectively, given at the beginning of and at aortic declamping in group U and group C. group S just received sham median thoracotomy. Venous blood samples were taken immediately after anesthesia induction in all three groups, 5- and 120-min post CPB in both group U and C, respectively; plasma markers of inflammation and CNS injury were compared. Pathology results of hippocampus were observed by light microscopy.

RESULTS

Statistically significant differences between group C and U were noted in the expression of inflammatory markers such as IL-10, TNF-α and neuron-specific enolase at 120-min post CPB. Brain injuries were observed in both groups (index cases and controls) and were milder in group U.

CONCLUSIONS

In our study, HLF CPB on infant piglets resulted in brain injury, and ulinastatin might reduce the extent of such injury.

Ketamine as a neuroprotective and anti-inflammatory agent in children undergoing surgery on cardiopulmonary bypass: a pilot randomized, double-blind, placebo-controlled trial

OBJECTIVE

Infants are potentially more susceptible to cell death mediated via glutamate excitotoxicity attributed to cardiopulmonary bypass. We hypothesized that ketamine, via N-methyl D-aspartate receptor blockade and anti-inflammatory effects, would reduce central nervous system injury during cardiopulmonary bypass.

METHODS

We randomized 24 infants, without chromosomal abnormalities, to receive ketamine (2 mg/kg, n = 13) or placebo (saline, n = 11) before cardiopulmonary bypass for repair of ventricular septal defects. Plasma markers of inflammation and central nervous system injury were compared at the end of surgery, and 6, 24, and 48 hrs after surgery. Magnetic resonance imaging and spectroscopy before cardiopulmonary bypass and at the time of hospital discharge were performed in a subset of cases and controls (n = 5 in each group). Cerebral hemodynamics were monitored postoperatively using near-infrared spectroscopy, and neurodevelopmental outcomes were assessed using Bayley Scales of Infant Development-II before and 2-3 wks after surgery.

RESULTS

Statistically significant differences were noted in preoperative inspired oxygen levels, intraoperative cooling and postoperative temperature, respiratory rate, platelet count, and bicarbonate levels. The peak concentration of C-reactive protein was lower in cases compared to controls at 24 hrs (p = .048) and 48 hrs (p = .001). No significant differences were noted in the expression of various cytokines, chemokines, S100, and neuron-specific enolase between the cases and controls. Magnetic resonance imaging with spectroscopy studies showed that ketamine administration led to a significant decrease in choline and glutamate plus glutamine/creatine in frontal white matter. No statistically significant differences occurred between pre- and postoperative Bayley Scales of Infant Development-II scores.

CONCLUSIONS

We did not find any evidence for neuroprotection or neurotoxicity in our pilot study. A large, adequately powered randomized control trial is needed to discern the central nervous system effect of ketamine on the developing brain. brain.

TRIAL REGISTRATION

The trial is registered at www.ClinicalTrials.gov, NCT00556361.

Systemic inflammatory response syndrome predicts increased mortality in patients after transcatheter aortic valve implantation

AIMS

The outcome of patients undergoing surgical or interventional therapy is unfavourably influenced by severe systemic inflammation. We assessed the impact of a systemic inflammatory response syndrome (SIRS) on the outcome after transcatheter aortic valve implantation (TAVI).

METHODS AND RESULTS

One hundred and fifty-two high-risk patients (mean age: 80.5 ± 6.5 years, mean logistic EuroSCORE: 30.4 ± 8.1%) with symptomatic severe aortic stenosis underwent TAVI. Proinflammatory cytokines [interleukin-6 (IL-6) and interleukin-8 (IL-8)], and acute phase reactants [C-reactive protein (CRP) and procalcitonin (PCT)] were measured at baseline and 1, 4, 24, 48, 72 h, and 7 days after TAVI. Sixty-one of 152 patients developed SIRS during the first 48 h after TAVI. Systemic inflammatory response syndrome patients were characterized by leucocytosis ≥12 × 10(9)/L (83.6 vs. 12.1%; P < 0.001), hyperventilation (80.3 vs. 35.2%; P < 0.001), tachycardia (37.7 vs. 9.9%; P < 0.001), and fever (31.1 vs. 3.3%; P < 0.001) compared with patients without SIRS. Furthermore, the occurrence of SIRS was characterized by a significantly elevated release of IL-6 and IL-8 with subsequent increase in the leucocyte count, CRP, and PCT. Major vascular complications [odds ratio (OR) 5.1, 95% confidence interval (CI): 1.3-19.6; P = 0.018] and the number of ventricular pacing runs (OR 1.7, 95% CI: 1.1-2.8; P = 0.025) were independent predictors of SIRS. The occurrence of SIRS was related to 30-day and 1-year mortality (18.0 vs. 1.1% and 52.5 vs. 9.9%, respectively; P < 0.001) and independently predicted 1-year mortality risk (hazard ratio: 4.3, 95% CI: 1.9-9.9; P < 0.001).

CONCLUSIONS

SIRS may occur after TAVI and is a strong predictor of mortality. The development of SIRS could be easily identified by a significant increase in the leucocyte count shortly after TAVI.

Patients With Severe Asymptomatic Carotid Artery Stenosis Do Not Have a Higher Risk of Stroke and Mortality After Coronary Artery Bypass Surgery

Background and Purpose—

Stroke development is a major concern in patients undergoing coronary artery bypass grafting (CABG). Whether asymptomatic severe carotid artery stenosis (CAS) contributes to the development of stroke and mortality in such patients remains uncertain.

Methods—

A retrospective analysis of 878 consecutive patients with documented carotid duplex ultrasound who underwent isolated CABG in our institution from January 2003 to December 2009 was performed. Patients with severe CAS (n=117) were compared with those without severe CAS (n=761) to assess the rates of stroke and mortality during hospitalization for CABG. The 30-day mortality rate was also assessed.

Results—

Patients with severe CAS were older and had a higher prevalence of peripheral arterial disease and heart failure. Patients with severe CAS had similar rates of in-hospital stroke (3.4% versus 3.6%; P =1.0) and mortality (3.4% versus 4.2%; P =1.0) compared with patients without severe CAS. The 30-day rate of mortality was also similar between the 2 cohorts (3.4% versus 2.9%; P =0.51).

Conclusions—

Severe CAS alone is not a risk factor for stroke or mortality in patients undergoing CABG. The decision to perform carotid imaging and subsequent revascularization in association with CABG must be individualized and based on clinical judgment.

Ce³+ ions determine redox-dependent anti-apoptotic effect of cerium oxide nanoparticles

Antioxidant therapy is the novel frontier to prevent and treat an impressive series of severe human diseases, and the search for adequate antioxidant drugs is fervent. Cerium oxide nanoparticles (nanoceria) are redox-active owing to the coexistence of Ce(3+) and Ce(4+) oxidation states and to the fact that Ce(3+) defects, and the compensating oxygen vacancies, are more abundant at the surface. Nanoceria particles exert outstanding antioxidant effects in vivo acting as well-tolerated anti-age and anti-inflammatory agents, potentially being innovative therapeutic tools. However, the biological antioxidant mechanisms are still unclear. Here, the analysis on two leukocyte cell lines undergoing apoptosis via redox-dependent or independent mechanisms revealed that the intracellular antioxidant effect is the direct cause of the anti-apoptotic and prosurvival effects of nanoceria. Doping with increasing concentrations of Sm(3+), which progressively decreased Ce(3+) without affecting oxygen vacancies, blunted these effects, demonstrating that Ce(3+)/Ce(4+) redox reactions are responsible for the outstanding biological properties of nanoceria.

The neuroinflammatory hypothesis of delirium

Delirium is a neuropsychiatric syndrome characterized by a sudden and global impairment in consciousness, attention and cognition. It is particularly frequent in elderly subjects with medical or surgical conditions and is associated with short- and long-term adverse outcomes. The pathophysiology of delirium remains poorly understood as it involves complex multi-factorial dynamic interactions between a diversity of risk factors. Several conditions associated with delirium are characterized by activation of the inflammatory cascade with acute release of inflammatory mediators into the bloodstream. There is compelling evidence that acute peripheral inflammatory stimulation induces activation of brain parenchymal cells, expression of proinflammatory cytokines and inflammatory mediators in the central nervous system. These neuroinflammatory changes induce neuronal and synaptic dysfunction and subsequent neurobehavioural and cognitive symptoms. Furthermore, ageing and neurodegenerative disorders exaggerate microglial responses following stimulation by systemic immune stimuli such as peripheral inflammation and/or infection. In this review we explore the neuroinflammatory hypothesis of delirium based on recent evidence derived from animal and human studies.

The inflammatory response to miniaturised extracorporeal circulation: a review of the literature

Conventional cardiopulmonary bypass can trigger a systemic inflammatory response syndrome similar to sepsis. Aetiological factors include surgical trauma, reperfusion injury, and, most importantly, contact of the blood with the synthetic surfaces of the heart-lung machine. Recently, a new cardiopulmonary bypass system, mini-extracorporeal circulation (MECC), has been developed and has shown promising early results in terms of reducing this inflammatory response. It has no venous reservoir, a reduced priming volume, and less blood-synthetic interface. This review focuses on the inflammatory and clinical outcomes of using MECC and compares these to conventional cardio-pulmonary bypass (CCPB). MECC has been shown to reduce postoperative cytokines levels and other markers of inflammation. In addition, MECC reduces organ damage, postoperative complications and the need for blood transfusion. MECC is a safe and viable perfusion option and in certain circumstances it is superior to CCPB.

Establishment of rat model of cardiopulmonary bypass in pulmonary hypertension

An experimental model of cardiopulmonary bypass in rats with pulmonary hypertension is necessary to understand underlying mechanisms and develop protective strategies. Male Sprague-Dawley rats were randomly divided into a sham group, cardiopulmonary bypass group, pulmonary hypertension group, and pulmonary hypertension with cardiopulmonary bypass group. Both groups with pulmonary hypertension received a subcutaneous injection of monocrotaline 60 mg x kg(-1) on day 0. Cardiopulmonary bypass was instituted in one of them 21 days later. The sham and pulmonary hypertension control groups underwent cannulation only. Cardiopulmonary bypass was conducted for 60 min at a flow rate of 100 mL x kg(-1) x min(-1). Hemodynamic investigations, blood gas analysis, interleukin-6, tumor necrosis factor-alpha, and survival studies were performed subsequently. Time-dependent increases of serum interleukin-6 and tumor necrosis factor-alpha were found after cardiopulmonary bypass in both groups. This model allows the study of multiple organ pathophysiological processes after cardiopulmonary bypass in rats with pulmonary hypertension, as well as the evaluation of possible protective strategies.

Development of post-pump syndrome in a sheep after mitral valve stenting

Summary

A one-year-old healthy sheep received an implant stenting the mural (‘posterior’) leaflet of the mitral valve. The experiment was authorized by the Cantonal Ethical Committee. The surgery was performed on the open, beating heart during cardiopulmonary bypass (CPB). Management of anaesthesia was based on isoflurane with mechanical intermittent positive pressure ventilation (IPPV) of the lungs, combined with intercostal nerve blocks and intravenous fentanyl and lidocaine. Marked cardiovascular depression occurred towards the end of CPB time and required high doses of dopamine, dobutamine, lidocaine and ephedrine to allow for weaning off the CPB pump. Moreover, severe pulmonary dysfunction developed when IPPV was re-initiated after CPB. Hypoxaemia persisted throughout the recovery from general anaesthesia. Multiple organ failure developed gradually during the three postoperative days, leading to euthanasia of the animal. As described in this case, marked lung injury associated with some degree of failure of other vital organs may occur in sheep after CPB. Intraoperative cardiorespiratory complications when weaning-off may indicate the development of ‘post-pump syndrome’.

Continuous cytometric bead processing within a microfluidic device for bead based sensing platforms

A microfluidic device for continuous biosensing based on analyte binding with cytometric beads is introduced. The operating principle of the continuous biosensing is based on a novel concept named the "particle cross over" mechanism in microfluidic channels. By carefully designing the microfluidic network the beads are able to "cross-over" from a carrier fluid stream into a recipient fluid stream without mixing of the two streams and analyte dilution. After crossing over into the recipient stream, bead processing such as analyte-bead binding may occur. The microfluidic device is composed of a bead solution inlet, an analyte solution inlet, two washing solution inlets, and a fluorescence detection window. To achieve continuous particle cross over in microfluidic channels, each microfluidic channel is precisely designed to allow the particle cross over to occur by conducting a series of studies including an analogous electrical circuit study to find optimal fluidic resistances, an analytical determination of device dimensions, and a numerical simulation to verify microflow structures within the microfluidic channels. The functionality of the device was experimentally demonstrated using a commercially available fluorescent biotinylated fluorescein isothiocyanate (FITC) dye and streptavidin coated 8 microm-diameter beads. After, demonstrating particle cross over and biotin-streptavidin binding, the fluorescence intensity of the 8 microm-diameter beads was measured at the detection window and linearly depends on the concentration of the analyte (biotinylated FITC) at the inlet. The detection limit of the device was a concentration of 50 ng ml(-1) of biotinylated FITC.

Minimizing Cardiopulmonary Bypass Attenuates Myocardial Damage After Cardiac Surgery

The standard heart-lung machine is deemed a major trigger of systemic inflammatory reactions, potentially inducing organ failure. The strict reduction of blood-artificial surface and blood-air contact might represent meaningful improvements of the extracorporeal technology with respect to organ preservation. In this study, we assessed perioperative myocardial damage by using a novel minimal extracorporeal circuit (MECC) and a conventional cardiopulmonary bypass (CPB) system. Sixty patients scheduled for coronary artery bypass surgery were randomly assigned to either the MECC or the standard CPB system. Myocardial markers were determined by specific immunoassays 6, 12, and 24 hours after CPB initiation. Results were corrected for hemodilution.Demographics, hemodynamics, the number of anastomoses, CPB, and cross-clamp time were comparable between the groups. MECC patients demonstrated significantly lower levels of Troponin T (ng/ml) at 6, 12, and 24 hours (0.07 +/- 0.01 vs. 0.16 +/- 0.04, p < 0.005; 0.12 +/- 0.03 vs. 0.28 +/- 0.08, p < 0.008; 0.21 +/- 0.05 vs. 0.35 +/- 0.09, p < 0.03, respectively) and creatine kinase-MB (U/l) at 6 and 12 hours (22.5 +/- 1.5 vs. 40.6 +/- 3.3, p < 0.0001; 23.3 +/- 3.4 vs. 40.8 +/- 8.0, p < 0.001, respectively). Creatine kinase-MB at 24 hours tended to lower values in the MECC group but did not quite reach statistical significance. The MECC system may not only provide a less invasive solution to meet the requirements during cardiac surgery but also a more organ-preserving alternative to standard CPB.

Microfluidic Devices for Continuous Blood Plasma Separation and Analysis During Pediatric Cardiopulmonary Bypass Procedures

As an extension of previous work, a microfluidic device, which can separate blood plasma in a continuous, real-time fashion from a whole blood, is successfully integrated with a mock cardiopulmonary bypass circuit. The functionality of the device is demonstrated with the use of freshly harvested bovine blood. The plasma selectivities were 100% and 99.4% and the plasma separation volume percents were 18.7% and 24.5% for 26% and 37% inlet hematocrit levels, respectively. As an advanced stage of this research, a microfluidic device, which can measure the concentration of clinically relevant blood plasma protein in a continuous fashion, is being developed on the basis of fluid handling circuits coupled to fluorescent cytometric bead assays. The functionality of the device is demonstrated with the use of a biotinylated FITC solution and a streptavidin-coated, 8-mum-diameter bead. The binding event between biotinylated FITC and the streptavidin bead is continuously detected within a detection window at the outlet of the device. For a known concentration (1 microg/ml) of biotinylated FITC solution, the measured fluorescent intensity is fairly constant and shows a stable gaussian distribution of the bead fluorescence intensity. It is expected that the proposed device can be used for continuous measurement of clinically relevant proteins during cardiac surgery with the cardiopulmonary bypass procedure.

How safe is it to train residents to perform off-pump coronary artery bypass surgery?

BACKGROUND

The technique of off-pump coronary artery bypass graft (OPCABG) surgery differs considerably from on-pump CABG. This study investigates the impact of surgical training on clinical outcome in patients undergoing OPCABG.

METHODS

All 251 OPCABG cases performed by one service over an 18-month period were analyzed. The 83 operations (33%) performed by two trainees under supervision were compared with the 168 operations (67%) performed by an experienced consultant surgeon. Patient and disease characteristics, intraoperative and postoperative data, morbidity and mortality were analyzed using univariate and multivariate analysis. Data were extracted from a prospective database.

RESULTS

Patients operated on by the consultant were more likely to have had unstable angina (p = 0.003, odds ratio [OR] = 3.5), impaired left ventricular function (ejection fraction < 0.3; p = 0.005, OR = 2.4), or previous cardiac surgery (p = 0.03). They were more likely to receive three or more grafts (p = 0.017, OR = 2.0). Operative mortality was 2.4% (consultant) and 0% (trainees; p = 0.31). Postoperative morbidity, such as reoperation for bleeding (consultant 3% versus trainees 1.2%), stroke (0.6% versus 1.2%), and hemofiltration (3.6% versus 0%) was similar between the two patient groups. Stay in the intensive care unit was not significantly different in the two groups.

CONCLUSIONS

In our experience, trainee surgeons are less likely to operate on patients with unstable angina or cardiac dysfunction. Operative morbidity and mortality are, however, similar in patients operated on by either an experienced consultant surgeon or trainees. We believe OPCABG can be taught safely to trainees under supervision.

Circulating endothelial cells demonstrate an attenuation of endothelial damage by minimizing the extracorporeal circulation

OBJECTIVE

Detachment of endothelial cells may represent serious injury of the endothelium after cardiopulmonary bypass. We investigated whether the extent of endothelial injury is related to the type of cardiopulmonary bypass system used (conventional or minimized) and determined circulating endothelial cells as well as von Willebrand factor and soluble thrombomodulin.

METHODS

Twenty patients scheduled for elective coronary bypass grafting were randomly assigned to either the minimal extracorporeal circulation system or the standard cardiopulmonary bypass. Ten healthy volunteers served as controls. Circulating endothelial cells per milliliter of full blood were perioperatively determined by immunomagnetic cell separation technique. Endothelial plasma markers were measured by enzyme-linked immunosorbent assay.

RESULTS

Preoperative circulating endothelial cell numbers did not differ between the experimental groups, but were significantly higher than in the healthy controls (18.6 +/- 5.6 vs 7.2 +/- 3.8, P < .001). At 6 hours, circulating endothelial cell numbers increased significantly compared with baseline in both experimental groups and peaked at 12 hours after cardiopulmonary bypass initiation, each time with significantly lower values in the minimal extracorporeal circulation group (6 hours: 44.0 +/- 9.9 vs 29.6 +/- 9.8, P = .007; 12 hours: 48.1 +/- 6.8 vs 31.8 +/- 7.1, P < .001). Likewise, von Willebrand factor and soluble thrombomodulin postoperatively increased in both groups with a tendency toward lower levels in the minimal extracorporeal circulation group. Although circulating endothelial cells gradually declined, continually with lower numbers in the minimal extracorporeal circulation group, the endothelial plasma markers remained elevated during observation time.

CONCLUSIONS

Circulating endothelial cells represent a novel marker of the intrinsic endothelial damage caused by cardiopulmonary bypass. Its analysis facilitates the evaluation of cardiopulmonary bypass modifications as the minimal extracorporeal circulation system could be proven to be less injurious to endothelium and myocardium.

A microfluidic device for continuous, real time blood plasma separation

A microfluidic device for continuous, real time blood plasma separation is introduced. The principle of the blood plasma separation from blood cells is supported by the Zweifach-Fung effect and was experimentally demonstrated using simple microchannels. The blood plasma separation device is composed of a blood inlet, a bifurcating region which leads to a purified plasma outlet, and a concentrated blood cell outlet. It was designed to separate blood plasma from an initial blood sample of up to 45% inlet hematocrit (volume percentage of cells). The microfluidic network was designed using an analogous electrical circuit, as well as analytical and numerical studies. The functionality of this device was demonstrated using defibrinated sheep blood. During 30 minutes of continuous blood infusion through the device, all the erythrocytes (red blood cells) traveled through the device toward the concentrated blood outlet while only the plasma was separated at the bifurcating regions and flowed towards the plasma outlet. The device has been operated continuously without any clogging or hemolysis of cells. The experimentally determined plasma selectivity with respect to blood hematocrit level was almost 100% regardless of the inlet hematocrit. The total plasma separation volume percent varied from 15% to 25% with increasing inlet hematocrit. Due to the device's simple structure and control mechanism, this microdevice is expected to be used for highly efficient continuous, real time cell-free blood plasma separation from blood samples for use in lab on a chip applications.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

The influence of propofol on P-selectin expression and nitric oxide production in re-oxygenated human umbilical vein endothelial cells

BACKGROUND

Reperfusion injury is characterized by free radical production and endothelial inflammation. Neutrophils mediate much of the end-organ injury that occurs, requiring P-selectin-mediated neutrophil-endothelial adhesion, and this is associated with decreased endothelial nitric oxide production. Propofol has antioxidant properties in vitro which might abrogate this inflammation.

METHODS

Cultured human umbilical vein endothelial cells were exposed to 20 h of hypoxia and then returned to normoxic conditions. Cells were treated with saline, Diprivan 5 microg/l or propofol 5 microg/l for 4 h after re-oxygenation and were then examined for P-selectin expression and supernatant nitric oxide concentrations for 24 h. P-selectin was determined by flow cytometry, and culture supernatant nitric oxide was measured as nitrite.

RESULTS

In saline-treated cells, a biphasic increase in P-selectin expression was demonstrated at 30 min (P = 0.01) and 4 h (P = 0.023) after re-oxygenation. Propofol and Diprivan prevented these increases in P-selectin expression (P < 0.05). Four hours after re-oxygenation, propofol decreased endothelial nitric oxide production (P = 0.035).

CONCLUSION

This is the first study to demonstrate an effect of propofol upon endothelial P-selectin expression. Such an effect may be important in situations of reperfusion injury such as cardiac transplantation and coronary artery bypass surgery. We conclude that propofol attenuates re-oxygenation-induced endothelial inflammation in vitro.

Blood plasma separation in microfluidic channels using flow rate control

Several studies have clearly shown that cardiac surgery induces systemic inflammatory responses, particularly when cardiopulmonary bypass (CPB) is used. CPB induces complex inflammatory responses. Considerable evidence suggests that systemic inflammation causes many postoperative complications. Currently, there is no effective method to prevent this systemic inflammatory response syndrome in patients undergoing CPB. The ability to clinically intervene in inflammation, or even study the inflammatory response to CPB, is limited by the lack of timely measurements of inflammatory responses. In this study, a microfluidic device for continuous, real-time blood plasma separation, which may be integrated with downstream plasma analysis device, is introduced. This device is designed to have a whole blood inlet, a purified plasma outlet, and a concentrated blood cell outlet. The device is designed to separate plasma with up to 45% hematocrit of the inlet blood and is analyzed using computational fluid dynamics simulation. The simulation results show that 27% and 25% of plasma can be collected from the total inlet blood volume for 45% and 39% hematocrit, respectively. The device's functionality was demonstrated using defibrinated sheep blood (hematocrit=39%). During the experiment, all the blood cells traveled through the device toward the concentrated blood outlet while only the plasma flowed towards the plasma outlet without any clogging or lysis of cells. Because of its simple structure and control mechanism, this microdevice is expected to be used for highly efficient, realtime, continuous cell-free plasma separation.

Effects on Lung Function in Patients Undergoing Coronary Artery Surgery on versus off Cardiopulmonary Bypass: A Randomized Trial

Background

Coronary revascularization is associated with respiratory dysfunction and poor gas exchange postoperatively. Cardiopulmonary bypass (CPB) has been implicated as a possible explanation for this phenomenon. This study investigated respiratory function in patients undergoing coronary artery bypass grafting (CABG) on-CPB versus off-CPB to determine whether the off-CPB condition results in improved postoperative pulmonary function.

Methods

Forty patients were randomized into 1 of 2 groups: CABG on-CPB (group A) or off-CPB (group B). Pulmonary function tests, including spirometry and diffusion studies, were performed preoperatively and on postoperative day 5. Arterial blood gases on 100% oxygen were taken preoperatively (TP1), 15 minutes after sternal closure (TP2), and 3 hours postoperatively (TP3).

Results

The arterial partial pressure of oxygen (PaO2) on FiO2 1.0 decreased from 59.5 ± 11.5 kPa and 55.7 ± 12.2 kPaat TP1 to 39.5 ± 16 kPa and 39.7 ± 13 kPa at TP2 in groups A and B, respectively (P < 0.001), with no significant difference between groups. At TP3, the PaO2 partially recovered toward preoperative levels (P < 0.05). Spirometry revealed a significant reduction in FEV1 and FVC on the fifth postoperative day (P < 0.001), with no significant difference between groups. The corrected transfer factor for carbon monoxide reduced significantly in group A from 7.9 ± 2.5 mmolmin–1 · kPa–1 preoperatively to 5.1 ± 1.6 mmolmin–1 · kPa–1 postoperatively (P < 0.05). This reduction was not seen in group B.

Conclusions

Coronary artery surgery is associated with a marked reduction in lung function as measured by pulmonary function tests and PaO2. Diffusion studies revealed that on-CPB patients had significantly reduced diffusion capacities postoperatively compared with patients in the off-CPB group.

Does transthoracic compared to transhiatal resection alter the early postoperative course of oesophagectomy?

Several techniques for esophageal resections have been reported. However, clear clinical evidence is still lacking whether any of the procedures is superior to the others regarding morbidity and mortality in the early postoperative period. Two operative approaches for esophageal carcinoma, transhiatal and transthoracic, were compared with respect to operative morbidity, mortality and systemic inflammatory response. In our prospective study between 2000 and 2002 83 patients were investigated. In a retrospective post hoc analysis patients were divided into two groups due to the performed operational procedure, transhiatal (TH) or transthoracic (TT). Multiple Organ Dysfunction Score (MODS) was monitored daily (t1,t2,t3). Serum procalcitonin (PCT) levels were determined on admission to the ICU (t0), then 24 hourly (t24,t48,t72). Microalbuminuria (M:Cr) was measured before (tp), and after surgery (t0,t6,t24,t48,t72). For statistical analysis Wilcoxon rank sum test, Mann-Whitney U-test and chi-square test were used as appropriate. We examined 52 patients in the TH group, and 31 patients in the TT group. There was no significant difference between the two groups regarding age, male/female ratio, and SAPS II scores. Operations lasted significantly longer in the TT group: 375 (300-480) min compared to the TH group 240 375 (180-319) min, P < 0.001. ICU mortality was similar in both groups (TH: 46 survivors/6 non-survivors; TT: 27 survivors/4 non-survivors; P = 0.607, respectively). Daily MODS did not differ significantly between the two groups. The observed inflammatory markers (PCT and M:Cr) followed the pattern we described earlier, without significant difference. In this study there was no difference in the clinical and biochemical variables of the patients between the transthoracic and transhiatal groups. The observed early postoperative morbidity and mortality may indicate, that both procedures can be considered as procedures with similar postoperative risk.

Renal Function After Cardiac Surgery Off- Versus On-Pump Coronary Artery Bypass: Analysis Using the Cockroft-Gault Formula for Estimating Creatinine Clearance

BACKGROUND

Cardiopulmonary bypass (CPB) is often associated with renal dysfunction, as measured by plasma creatinine levels and hemodialysis rates. This study compared creatinine clearance (CrCl), estimated with the Cockroft and Gault formula, between patients undergoing off-pump coronary artery bypass grafting (OPCAB) versus on-pump CABG (on-CAB).

METHODS

Data of 704 consecutive patients were analyzed. Of these patients, 404 underwent OPCAB while 300 had on-CAB. Creatinine clearance, plasma creatinine levels, and clinical outcome were compared between groups. Data between patients who developed new renal impairment, compared to patients with normal postoperative renal function, were also analyzed.

RESULTS

Creatinine clearance (preoperative, 74 +/- 25 vs 78 +/- 29 mL/min; day 1, 74 +/- 26 vs 76 +/- 31 mL/min; day 4, 70 +/- 26 vs 72 +/- 29 mL/min) and creatinine levels (preoperative, 99 +/- 25 vs 95 +/- 27 micromol/L; day 1, 101 +/- 29 vs 104 +/- 35 micromol/L; day 4, 110 +/- 44 vs 113 +/- 60 micromol/L), as well as postoperative complications (stroke 1% vs 1%; hemofiltration 1.5% vs 3.7%; death 1.2% vs 2.3%), were overall similar between OPCAB and on-CAB patients. Patients with preoperative CrCl less than 50 mL/min had higher creatinine levels in the on-CAB group on day 1 (p = 0.026), although CrCl was similar between groups. Development of new CrCl less than 50 mL/min postoperatively was associated with higher rates of intraaortic balloon pump insertion, re-sternotomy, hemofiltration, intensive care and hospital stay, without difference between groups. Female sex, low body mass index, high preoperative creatinine levels, and advanced age were associated with deterioration in CrCl.

CONCLUSIONS

Currently, the rate of renal impairment is low after both OPCAB and on-CAB. No significant difference in CrCl could be demonstrated between groups. Deterioration in renal function is associated with higher rates of postoperative complications.

A rat model of cardiopulmonary bypass with excellent survival

BACKGROUND

Elucidating the underlying mechanisms and developing protective strategies for the pathophysiological consequences of cardiopulmonary bypass (CPB) have been hampered due to the absence of a satisfactory long-term recovery animal model. The objective of this study was to establish a survival experimental model of CPB in rats to meet the requirement of these studies.

MATERIALS AND METHODS

Male SD rats (450-550 g) were randomly divided into CPB (n = 10) group and Sham group (n = 10). All rats were anaesthetized and mechanically ventilated. The femoral artery and vein were cannulated for continuous blood pressure recordings and fluid replacement, respectively. The CPB circuit comprised a venous reservoir, a membrane oxygenator, and a roller pump. Blood was drained from the right atrium via a jugular vein catheter and returned to the right carotid artery. Priming consisted of 8 ml of homologous blood and 8 ml of colloid. CPB was conducted for 60 min at a flow rate of 100-150 ml/kg/min in the CPB group. Haemodynamic investigations, blood gas analysis, and survival studies were performed subsequently.

RESULTS

Our data show that the rat model principally simulated the clinical setting of CPB in terms of its construction, configuration, performance, material surface area, and priming volume to blood volume ratio. All CPB rats survived and the 2-week follow-up period remained uneventful.

CONCLUSIONS

The rat model of CPB was easy to establish and was associated with excellent survival. This model should facilitate the investigation of the pathophysiological processes concerning CPB-related multiple organ dysfunction and possible protective interventions.

Effects of transfusion with red cells filtered to remove leucocytes: randomised controlled trial in patients undergoing major surgery

OBJECTIVE

To compare postoperative complications in patients undergoing major surgery who received non-filtered or filtered red blood cell transfusions.

DESIGN

Prospective, randomised, double blinded trial.

SETTING

19 hospitals throughout the Netherlands (three university; 10 clinical; six general).

PARTICIPANTS

1051 evaluable patients: 79 patients with ruptured aneurysm, 412 patients undergoing elective surgery for aneurysm, and 560 undergoing gastrointestinal surgery.

INTERVENTIONS

The non-filtered products had the buffy coat removed and were plasma reduced. The filtered products had the buffy coat removed, were plasma reduced, and filtered before storage to remove leucocytes.

MAIN OUTCOME MEASURES

Mortality and duration of stay in intensive care. Secondary end points were occurrence of multi-organ failure, infections, and length of hospital stay.

RESULTS

No significant differences were found in mortality (odds ratio for filtered v non-filtered 0.80, 95% confidence interval 0.53 to 1.21) and in mean stay in intensive care (- 0.4 day, - 1.6 to 0.6 day). In the filtered group the mean length of hospital stay was 2.4 days shorter (- 4.8 to 0.0 day; P = 0.050) and the incidence of multi-organ failure was 30% lower (odds ratio 0.70, 0.49 to 1.00; P = 0.050). There were no differences in rates of infection (0.98, 0.73 to 1.32).

CONCLUSION

The use of filtered transfusions in some types of major surgery may reduce the length of hospital stay and the incidence of postoperative multi-organ failure.

Inflammatory response in an immunosuppressed patient with Wegener's granulomatosis

BACKGROUND

The use of cardiopulmonary bypass (CPB) triggers a systemic inflammatory response (IR), but it is not known if a similar response occurs in an immunosuppressed patient with autoimmune disease.

METHODS AND RESULTS

Observational study in a 56-year-old man receiving immunosuppressive therapy for Wegener's granulomatosis (WG) who underwent aortic valve replacement on CPB. The following markers for IR were studied in the perioperative period: C3a, C5a, neutrophil elastase (NE), interleukin eight (IL-8), white cell count (WCC) and C-reactive protein (CRP). Results were compared with published literature on the IR in patients undergoing coronary revascularisation with and without the use of CPB. All inflammatory markers increased in the perioperative period. The intensity of IR was markedly reduced compared to published literature for patients undergoing coronary revascularisation on CPB and the temporal patients and extend resembled that for off-pump.

CONCLUSION

In a patient with WG on immunosuppressive therapy the CPB-related IR is reduced.

Chronologic distribution of stroke after minimally invasive versus conventional coronary artery bypass

OBJECTIVES

We sought to investigate whether the chronologic distribution of the onset of stroke occurring after coronary artery bypass graft surgery (CABG) without cardiopulmonary bypass (off-pump CABG) is different from the conventional on-pump approach (CABG with cardiopulmonary bypass).

BACKGROUND

Off-pump CABG has been associated with a lower stroke rate, compared with conventional on-pump CABG. However, it is unknown whether the chronologic distribution of the onset of stroke is different between the two approaches.

METHODS

We evaluated the chronologic distribution of postoperative stroke in patients undergoing CABG from June 1996 to August 2001 (n = 10,573). Preoperative risk factors for stroke were identified using the Northern New England preoperative estimate of stroke risk. Multivariate logistic regression analysis was used to determine the independent predictors of early stroke and to delineate the association between the surgical approach and the chronologic distribution of the onset of stroke.

RESULTS

Stroke occurred in 217 patients (2%, n = 10,573). A total of 44 (20%) and 173 (80%) of these patients had stroke after off-pump CABG and on-pump CABG, respectively. The median time for the onset of stroke was two days (range 0 to 11 days) after on-pump CABG versus four days (range 0 to 14 days) after off-pump CABG (p < 0.01). On-pump CABG was associated with a higher risk of early stroke (odds ratio 5.3, 95% confidence interval 2.6 to 10.9; p < 0.01) compared with off-pump CABG.

CONCLUSIONS

Compared with off-pump CABG, on-pump CABG is associated with an earlier onset of postoperative stroke during the recovery phase, suggesting different mechanisms in the pathogenesis of stroke between the two surgical approaches.