Soluble urokinase plasminogen activator receptor predicts survival and hospitalization for heart failure in elective cardiac surgery

Aims

The study investigated the prognostic value of soluble urokinase plasminogen activator receptor (suPAR) patients undergoing cardiac surgery and calculated a simplified biomarker score comprising suPAR, N-terminal pro B-type natriuretic peptide (NT-proBNP) and age.

Methods and results

Biomarkers were assessed in a cohort of 478 patients undergoing elective cardiac surgery. After a median follow-up of 4.2 years a total of 72 (15.1%) patients died. SuPAR, NT-proBNP and age were independent prognosticators of mortality in a multivariable Cox regression model after adjustment for EuroScoreII. We then calculated a simplified biomarker score comprising age, suPAR and NT-proBNP, which had a superior prognostic value compared to EuroScoreII (Harrel's C of 0.76 vs 0.72; P for difference = 0.02). Besides long-term mortality, the biomarker score had an excellent performance predicting one-year mortality and hospitalization due to heart failure.

Conclusion

The biomarker suPAR and NT-proBNP were strongly and independently associated with mortality in patients undergoing cardiac surgery. A simplified biomarker score comprising only 3 variables (age, suPAR and NT-proBNP) performed better than the established EuroScoreII with respect to intermediate and long-term outcome as well as hospitalization due to heart failure. As such, integration of established and upcoming biomarkers in clinical practice may provide improved decision support in cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

Fibroblast growth factor-23 is an independent predictor of hospitalization for heart failure and major cardiovascular adverse events in patients undergoing cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) plays a crucial role in regulating phosphate and vitamin D metabolism and was proved to be associated with an increased risk for fatal events in individuals suffering from cardiovascular diseases. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery are scarce, the specific objective of this study was to investigate the impact of FGF-23 on postoperative complications, particularly postoperative atrial fibrillation (POAF), hospitalization for heart failure (HHF) and cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of a medical university. Blood samples were taken prior to surgery and FGF-23 concentrations were subsequently assessed. Patients were followed prospectively until the primary study endpoint (CV death) was reached.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF-23 level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). Notably, individuals with POAF showed significantly higher FGF-23 levels than patients without (p<0.001). After stratification into tertiles (T) of FGF-23 patients in the highest FGF-23 tertile showed greater rates of HHF, all-cause and CV death. Furthermore, FGF-23 was consistently associated with POAF development showing an adjusted OR for a 1-unit increase in standardized log-transformed biomarker of 1.28 (95% CI: 1.01 to 1.63), along with an adjusted OR of 2.04 (95% CI 1.33 to 3.13, p=0.001) for the pre-defined high risk cut-off value. A steady risk increase for HHF and CV death among ascending FGF-23 tertiles has been noted. Moreover FGF-23 showed strong discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77). Reclassification analysis indicated that the addition of FGF-23 to NT-proBNP provides a significant improvement in risk discrimination (NRI at the event rate: 0.58, 95% CI 0.34–0.81, p-value <0.001; IDI: 0.03, 95% CI 0.01–0.05, p-value= 0.001).

Conclusion

FGF-23 proved to be a strong and independent predictor for POAF, HHF and CV death in individuals undergoing cardiac surgery. Considering an individualized risk assessment, routine preoperative FGF-23 evaluation may improve detection of patients at risk, who require in-depth clinical attention throughout the peri- and postoperative phase after cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

The impact of left atrial mechanics on adverse events and clinical outcome after cardiac surgery

Objectives

Post-operative atrial fibrillation (POAF) represents a common complication after cardiac surgery that is associated with unfavorable clinical outcome. Identifying patients at risk for POAF is crucial but challenging.

Purpose

This study aimed to investigate the prognostic potential of speckle tracking echocardiography (STE) on POAF and fatal adverse events from a long-term perspective.

Methods

A total of 124 patients undergoing elective cardiac surgery were prospectively enrolled and underwent pre-operative STE. Patients were followed prospectively for the occurrence of POAF within the entire hospitalization and reaching the secondary endpoints cardiovascular (CV) and all-cause mortality.

Results

Within the study population 43.5% (n=53) of enrolled individuals developed POAF. After a median follow-up of 3.9 years, 25 (20.2%) patients died. We observed that patients presenting with POAF had lower global peak atrial longitudinal strain (PALS) values compared to the non-POAF arm (POAF: 14.8% [95% CI: 10.9–17.8] vs. non-POAF: 19.4% [95% CI: 14.8–23.5], p<0.001). Moreover, global PALS was a strong and independent predictor for POAF (adjusted Odds Ratio per 1-SD: 0.37 [95% CI: 0.22–0.65], p<0.001), and independently associated with mortality (adjusted Hazard Ratio per 1-SD: 0.63 [95% CI: 0.40–0.99], p=0.048). CART analysis revealed a cut-off value of <17% global PALS as high-risk for both POAF and mortality.

Conclusion

Global PALS is associated with the development of POAF following surgery in an unselected patient population undergoing CABG and/or valve surgery. Since patients with global PALS <17% face a poor long-term prognosis, routine assessment of global PALS needs to be considered in terms of proper secondary prevention in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None.

The prognostic impact of fibroblast growth factor-23 on cardiovascular death after cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) participates in phosphate and vitamin D metabolism and proved to be associated with an increased risk for fatal events in individuals presenting with cardiovascular disease. In the era of personalized medicine and individualized prognostication, the identification of novel risk markers seems of major importance in terms of state-of-the-art patient care. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery remain scarce, we aimed to investigate the impact of FGF-23 on cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of our Medical University. Preoperative blood values were assessed immediately before the surgical intervention. FGF-23 concentrations were measured via FGF Quantikine ELISA Kit (R&D Systems, Minneapolis, USA). Patients were followed prospectively until the primary study endpoint (CV death) was reached. Cox regression models were calculated and adjusted for age, sex, diabetes, heart failure, body mass index, prior myocardial infarction, hypertension and coronary artery disease.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). After stratification into tertiles (T) of FGF-23 (median FGF-23 T1: 0.95 pmol/L [IQR 0.65 to 1.19], T2: 1.93 pmol/L [IQR 1.64 to 2.28] T3: 4.80 pmol/L [IQR 3.54 to 8.09]), patients in the highest FGF-23 tertile had highest rates of CV death (T1: 4.8%, T2: 6.8%, T3: 19.1%; P-logrank <0.001; Figure A). Moreover, there was a strong association between FGF-23 and CV death (Adj. hazard ratio for 1-unit increase in standardized log-transformed biomarker 1.44, 95% CI: 1.19 to 1.75; P-value <0.001). The risk of CV death increased within higher tertiles of FGF-23 (T3: adj. HR 3.59 [95% CI 1.48–8.71], P-value= 0.005) (T1 was chosen as reference). FGF23 also showed good discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77).

Conclusion

FGF-23 proved to be a strong and independent predictor for CV death in individuals undergoing elective cardiac valve and/or CABG surgery. This biomarker may provide improved risk assessment and fosters individualized patient care in this highly vulnerable patient population in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Kaplan Meier curves

The prognostic potential of growth differentiation factor-15 on bleeding events and patient outcome after cardiac surgery

Background

GDF-15 (growth/differentiation factor 15) is induced by myocardial stretch, volume overload, inflammation and oxidative stress. Its expression is tightly linked with cardiovascular events as well as the risk for major bleeding and all-cause mortality.

Objective

The objective of the present study was to elucidate the prognostic potential of GDF-15 in patients after cardiac surgery.

Methods

504 patients undergoing elective cardiac valve and/or coronary artery bypass graft surgery were prospectively enrolled. GDF-15 levels were measured prior surgery to evaluate the impact on bleeding events, thromboembolic events and mortality.

Results

Preoperative GDF-15 was associated with the primary endpoint of intra- and postoperative red blood cell transfusion (for bleeding risk factors adjusted [adj] OR [odds ratio] per 1-SD [standard deviation] of 1.62 [95% CI: 1.31–2.00]; p<0.001) and postoperative atrial fibrillation (for atrial fibrillation risk factors adj. OR per 1-SD of 1.49 [95% CI: 1.22–1.81]; p<0.001). Higher concentrations of GDF-15 were observed in patients reaching the secondary endpoint of major or clinically relevant minor bleeding (for bleeding risk factors adj. OR per 1-SD of 1.70 [95% CI: 1.05–2.75]; p=0.030) during the 1stpostoperative year, but not for thromboembolic events. GDF-15 was a predictor for cardiovascular mortality (for comorbidities adj. HR [hazard ratio] per 1-SD of 1.67 [95% CI: 1.23–2.27]; p=0.001) and all-cause mortality (for comorbidities adj. HR per 1-SD of 1.55 [95% CI: 1.19–2.01]; p=0.001). A combined risk model of GDF-15 and EuroSCORE II outperformed the EuroSCORE II alone for long-term survival (c-index: 0.75 [95% CI: 0.70–0.80], p=0.046; net reclassification improvement: 33.6%, p<0.001).

Conclusion

Preoperative GDF-15 concentration is an independent predictor for intra- and postoperative major bleeding, major bleeding during the first year and for long-term cardiovascular or all-cause mortality after cardiac surgery.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Medical University of Vienna Central illustration

The prognostic impact of therapeutic anticoagulation after biological aortic valve replacement

Background

Recent guidelines state that in patients with surgical biological aortic valve replacement (AVR), the use of anti-platelet therapy is as a valid alternative to postoperative anticoagulation (AC) in the absence of a further indication for AC. However, the prognostic impact of different anti-thrombotic strategies after biological AVR has not clearly been investigated so far and outcome data remain scare and inconclusive. Moreover, the AC strategy of patients presenting with post-operative atrial fibrillation (POAF), has not been investigated so far. Therefore, we aim to picture the therapeutic AC approach after biological AVR and whether the presence of POAF effects decision making with regard to anti-thrombotic management.

Methods

Within this prospective observational study 515 patients undergoing elective cardiac valve and or coronary artery bypass graft (CABG) surgery were enrolled. All patients were continuously screened for the development of POAF and followed until the primary endpoint (mortality) was reached. Logistic regression analysis was performed to elucidate the effect of AC on outcome.

Results

A total of 200 individuals underwent biological AVR (including 81 [40.3%] combined AVR+CABG surgeries, median age: 77 years [IQR: 71–80 years]; 133 [66.3%] male gender). 97 (48.3%) patients received therapeutic AC at the time of discharge, including 42 (43.4%) on vitamin K antagonists (VKA), 53 (54.6%) on low-dose low-molecular weight heparin (LMWH) and 2 (2.0%) non-vitamin K antagonist oral anticoagulants (NOACs). 103 (51.2%) patients received another anti-thrombotic approach including 23 (22.3%) on dual anti-platelet therapy (DAPT) and 72 (69.9%) with prophylactic LMWH. Interestingly, the fraction of patients that received AC were comparable between POAF (CHA2DS2-Vasc score 4, IQR: 3–5) and non-POAF individuals (51.9% vs. 44.6%; p=0.304). After a median follow-up time of 1069 days (IQR: 673–1475 days) 21 patients (10.4%) died, referring to 9 (8.3%) non-POAF and 12 (13.0%) POAF individuals. We found that a therapeutic AC after surgery showed a strong and inverse association with 3-year mortality with a crude odds ratio (OR) of 0.31 (95% CI 0.12–0.79; p=0.015). The prognostic potential remained stable after adjustment for potential confounders (p=0.029).

Conclusion

Therapeutic AC showed a strong and independent inverse association with 3-year mortality, mirroring a potential benefit on outcome compared to anti-platelet therapy or low-dose LMWH. However, the fraction of patients receiving therapeutic AC was considerably low – especially NOACs were not commonly used. Despite its association with fatal cardiac adverse events, the presence of POAF was not a relevant value for decision making for the initiation of AC. Further prognostic data on both thromboembolic and bleeding events are needed to elucidate a net-benefit of therapeutic AC in patients with surgical biological AVR who have an indication for AC or present with POAF.

Kaplan-Meier Survival plot

Funding Acknowledgement

Type of funding source: None

Hemodynamic effects of Vernakalant in cardio-surgical ICU-patients treated for recent-onset postoperative atrial fibrillation

Postoperative atrial fibrillation (POAF) is one of the most frequent complications after cardiothoracic surgery and a predictor for postoperative mortality and prolonged ICU-stay. Current guidelines suggest the multi-channel inhibitor Vernakalant as a treatment option for rhythm control. However, rare cases of severe hypotension and cardiogenic shock following drug administration have been reported. To elucidate the impact of Vernakalant on hemodynamics, we included ten ICU patients developing POAF after elective cardiac surgery, all of them awake and breathing spontaneously, in this prospective trial. Patients received the recommended dosage of Vernakalant and were clinically observed and monitored (heart rate, invasive blood pressure, pulse oximetry, central venous pressure) in 1-minute-intervals for 20 minutes before- and 120 minutes after the first dose of Vernakalant. The median time from the end of surgery until occurrence of POAF amounted up to 52.8 [45.9–77.4] hours, it took 3.5 [1.2–10.1] hours from occurrence of POAF until the first application of Vernakalant. All patients received catecholamine support with epinephrine that was held steady and not dynamic throughout the observational phase. We noted stable hemodynamic conditions, with a trend towards a reduction in heart rate throughout the 120 minutes after drug administration. In 7 patients (70%), conversion to sustained sinus rhythm (SR) occurred within 8.0 minutes [6.0–9.0]. No serious adverse events (SAEs) were noted during the observation period. In this prospective trial in ICU-patients showing POAF after cardiac surgery, intravenous Vernakalant did not induce clinically relevant negative effects on patients’ hemodynamics but resulted in conversion to sustained SR after a median of 8.0 minutes in 7 out of ten patients.

P4736The Prognostic Impact of Volume Substitution on Cardiac Strain and the Development of Postoperative Atrial Fibrillation after Cardiac Surgery

Background

Postoperative atrial fibrillation (POAF) represents a common complication after cardiac valve or coronary artery bypass surgery. Etiologically, multifactorial causes such as the patients' age, weight, comorbidities or local remodeling proved a strong association with this common arrhythmia. While strain of atrial tissue is known to induce atrial fibrillating impulses, less attention has been paid to potentially strain-promoting values during the peri- and post-operative period. Therefore, we aimed to determine the association of peri- and post-operative volume substitution on markers of cardiac strain and subsequently its impact on the promotion and development of POAF.

Methods

In this prospective observational study 271 patients undergoing elective cardiac surgery in our Medical University were enrolled (median age: 69 years [IQR: 60–75 years]; 195 [72%] male gender). Intra- and post-operative data was collected from anesthesiologic and intensive care unit protocols. Multivariate binary logistic regression analysis was used to identify the prognostic value of volume substitution on the development of POAF.

Results

A total of 123 (45.4%) individuals developed POAF. The average intra-operative transfusion volume was significantly elevated in the POAF subgroup (605.6ml [POAF] vs. 227.1ml [non-POAF]; p<0.001). Moreover, the fluid balance within the first 24 hours after surgery was significantly higher in patients developing POAF (+1129.6 ml [POAF] vs. +544.9 ml [non-POAF]; p=0.044). We found that N-terminal pro brain natriuretic peptide (NT-proBNP) values were significantly elevated in patients that received any volume substitution (2860.0 pg/mL [Transfusion] vs. 1486.5 pg/mL [no-Transfusion]; p=0.002). In line with those results, the postoperative fluid balance was also found to have a direct and significant correlation with postoperative NT-ProBNP values (r=0.287, p=0.002). Of note, the amount of substituted volume proved to be a strong and independent predictor for POAF with an adjusted odds-ratio (OR) per one standard deviation (1-SD) of 2.49 (95% CI: 1.25–4.96; p=0.009).

Conclusion

Within the present analysis we were able to demonstrate that substitution of larger transfusion volumes presents a strong and independent predictor for the development of POAF. Via the observed distinct association with NT-proBNP values, it can reasonably be assumed that post-operative atrial fibrillating impulses are triggered via volume-induced cardiac strain.

P1891CD8+CD28null T lymphocytes are associated with the development of atrial fibrillation after elective cardiac surgery

Background

Post-operative atrial fibrillation (POAF) is assumed as a complex and multifactorial interaction of different pathogenic factors. Data suggests an inflammatory process as a main trigger of this specific type of atrial fibrillation. CD8+ T lymphocytes that lack the surface protein CD28 were found to be crucially involved in chronic inflammatory processes within the cardiovascular system. Of utmost interest, these so called CD8+CD28null T cells are known to present with auto-aggressive behavior and deleterious cytotoxic effects on human tissue. Therefore, the impact of cellular immunity on the development of POAF was sought to assess.

Methods

To elucidate the impact of cellular immunity on the development of POAF, we prospectively enrolled 129 patients undergoing elective cardiac valve and/or coronary-artery-bypass-graft surgery. Fluorescein-activated cell sorting (FACS) was performed to investigate lymphocyte subsets. Patients were stratified in two subgroups according to patients developing POAF (n=60) and individuals free of POAF (n=69). Binary logistic regression analysis was performed to assess the impact of cellular immunity on the development of POAF.

Results

Comparing patients developing POAF to individuals free of POAF the fraction of CD8+ lymphocytes was significantly higher in individuals developing POAF (30.5% [POAF] vs. 25.7% [non-POAF]; p=0.021) Interestingly, the fraction of CD8+CD28nullT-lymphocytes was significantly higher in the POAF sub-group (66.7% [POAF] vs. 61.6% [non-POAF]; p=0.043). Binary logistic regression further proved that the fraction of CD8+CD28null T cells was a strong prognosticator for the development of POAF with a crude odds ratio per one standard deviation of 3.45 (95% CI 1.11–10.70; p=0.032). The prognostic potential remained stable after adjustment for potential confounders (age, male gender and type of surgery) within the multivariate model with an adjusted odds ratio per one standard deviation of 3.21 (95% CI 1.01–10.18; p=0.048).

Conclusion

We found that cytotoxic CD8+CD28null T lymphocytes proved to be a strong and independent predictor for the development of POAF after elective cardiac surgery. Our results potentially indicate an auto-immune impact of this preexisting, highly cytotoxic T cell subset in the pathogenesis of POAF.

Acknowledgement/Funding

Verein zur Förderung der Forschung – Atherosclerosis Thrombosis and Vascular Biology (Vienna, Austria)

Beneficial effects of levosimendan on survival in patients undergoing extracorporeal membrane oxygenation after cardiovascular surgery

BACKGROUND

The impact of levosimendan treatment on clinical outcome in patients undergoing extracorporeal membrane oxygenation (ECMO) support after cardiovascular surgery is unknown. We hypothesized that the beneficial effects of levosimendan might improve survival when adequate end-organ perfusion is ensured by concomitant ECMO therapy. We therefore studied the impact of levosimendan treatment on survival and failure of ECMO weaning in patients after cardiovascular surgery.

METHODS

We enrolled a total of 240 patients undergoing veno-arterial ECMO therapy after cardiovascular surgery at a university-affiliated tertiary care centre into our observational single-centre registry.

RESULTS

During a median follow-up period of 37 months (interquartile range 19-67 months), 65% of patients died. Seventy-five per cent of patients received levosimendan treatment within the first 24 h after initiation of ECMO therapy. Cox regression analysis showed an association between levosimendan treatment and successful ECMO weaning [adjusted hazard ratio (HR) 0.41; 95% confience interval (CI) 0.22-0.80; P=0.008], 30 day mortality (adjusted HR 0.52; 95% CI 0.30-0.89; P=0.016), and long-term mortality (adjusted HR 0.64; 95% CI 0.42-0.98; P=0.04).

CONCLUSIONS

These data suggest an association between levosimendan treatment and improved short- and long-term survival in patients undergoing ECMO support after cardiovascular surgery.

Reparixin, a Specific Interleukin-8 Inhibitor, Has No Effects on Inflammation during Endotoxemia

Reparixin antagonizes interleukin-8 (IL-8) on the level of signal transduction in vitro. We hypothesized that IL-8 mediates some of the reactions occurring during acute inflammation and specifically that IL-8 may be a mediator of endotoxin induced neutrophilia. We therefore tested the effects of reparixin on humoral and cellular parameters in LPS-induced acute systemic inflammation. The study is a randomized (3:2 active:placebo), double-blind, placebo-controlled parallel group trial. Twenty healthy male volunteers randomly received either reparixin (12) or placebo (8) intravenously. One hour after the start of reparixin/placebo infusion a bolus of 2 ng/kg endotoxin was infused over 1–2 min. Blood samples were obtained over 24 h. Reparixin, being metabolized to ibuprofen, suppressed serum thromboxane B2 levels by 78% compared to baseline and control at 8 h. LPS-induced neutrophilia was not significantly affected by reparixin in human volunteers. Consistently, reparixin did not alter the lymphocyte or monocyte counts and had no effect on LPS-induced systemic inflammation as measured by tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6) release. Regulation of IL-8 receptors CXCR1 and 2 and the degranulation marker CD11b showed the expected kinetics. Reparixin had no effect on thrombin formation as measured by prothrombin fragment (F1+2). In conclusion, our study showed that reparixin was safe but had no impact on endotoxin induced inflammation. In contrast to previous studies with its metabolite ibuprofen, reparixin does not enhance inflammation in this model.

A pilot study on reparixin, a CXCR1/2 antagonist, to assess safety and efficacy in attenuating ischaemia-reperfusion injury and inflammation after on-pump coronary artery bypass graft surgery

Reparixin, a CXCR 1/2 antagonist, has been shown to mitigate ischaemia-reperfusion injury (IRI) in various organ systems in animals, but data in humans are scarce. The aim of this double-blinded, placebo-controlled pilot study was to evaluate the safety and efficacy of reparixin to suppress IRI and inflammation in patients undergoing on-pump coronary artery bypass grafting (CABG). Patients received either reparixin or placebo (n = 16 in each group) after induction of anaesthesia until 8 h after cardiopulmonary bypass (CPB). We compared markers of systemic and pulmonary inflammation, surrogates of myocardial IRI and clinical outcomes using Mann-Whitney U- and Fisher's exact tests. Thirty- and 90-day mortality was 0% in both groups. No side effects were observed in the treatment group. Surgical revision, pleural and pericardial effusion, infection and atrial fibrillation rates were not different between groups. Reparixin significantly reduced the proportion of neutrophil granulocytes in blood at the beginning [49%, interquartile range (IQR) = 45-57 versus 58%, IQR = 53-66, P = 0·035], end (71%, IQR = 67-76 versus 79%, IQR = 71-83, P = 0·023) and 1 h after CPB (73%, IQR = 71-75 versus 77%, IQR = 72-80, P = 0·035). Reparixin patients required a lesser positive fluid balance during surgery (2575 ml, IQR = 2027-3080 versus 3200 ml, IQR = 2928-3778, P = 0·029) and during ICU stay (2603 ml, IQR = 1023-4288 versus 4200 ml, IQR = 2313-8160, P = 0·021). Numerically, more control patients required noradrenaline ≥ 0·11 μg/kg/min (50 versus 19%, P = 0·063) and dobutamine (50 versus 25%, P = 0·14). Therefore, administration of reparixin in CABG patients appears to be feasible and safe. It concurrently attenuated postoperative granulocytosis in peripheral blood.

Intravenous immunoglobulins induce CD32-mediated platelet aggregation in vitro

BACKGROUND

Intravenous immunoglobulins (IVIg) and cytomegalovirus immunoglobulins (CMVIg) are currently finding increased acceptance in clinical states of high immune activity and in transplant recipients. A rare side-effect of their application is intravascular thrombosis, which is thought to be related to pre-existing hyperviscosity. In a previous study we have shown that rabbit antithymocyte globulin causes platelet aggregation in vitro via the Fc IgG receptor (CD32).

OBJECTIVES

To investigate if IVIg and CMVIg have the potential to cause CD32-dependent platelet aggregation.

METHODS

The influence of CMVIg or IVIg on platelets pre-incubated with or without monoclonal antibody AT10 was studied in an aggregometer. Expression of platelet surface activation marker CD62P was determined by fluorescence-activated cell sorting analysis and presence of soluble CD40L (sCD40L) was evaluated by enzyme-linked immunosorbent assay. All in vitro experiments were performed using platelet concentrates from the blood bank, at therapeutic concentrations of immunoglobulins. Results Incubation of platelets with CMVIg and IVIg markedly induced platelet aggregation, and increased expression of CD62P and secretion of sCD40L. The capacity of CMVIg and IVIg to induce platelet aggregation was completely abrogated by adding the blocking antibody AT10 directed against the low-affinity Fc IgG receptor (CD32).

CONCLUSIONS

Our results suggest that CMVIg and IVIg solutions with activating Fc domains are able to bind CD32 on platelets and cause platelet aggregation in vitro. These results indicate a mechanism by which in vivo intravascular thrombosis may be explained and suggest caution with concomitant use of packed platelets and IVIg in autoimmune diseases in the clinical setting.

Low-dose remifentanil to suppress haemodynamic responses to noxious stimuli in cardiac surgery: a dose-finding study

BACKGROUND

High-dose remifentanil (1-5 microg kg-1 min-1), commonly used for cardiac surgery, has been associated with muscle rigidity, hypotension, bradycardia, and reduced cardiac output. The aim of this study was to determine an optimal lower remifentanil dose, which should be accompanied by fewer adverse events, that still effectively suppresses haemodynamic responses to typical stressful stimuli (i.e. intubation, skin incision, and sternotomy).

METHODS

Total i.v. anaesthesia consisted of a target-controlled propofol (2 microg ml-1) and a remifentanil infusion. Forty patients were allocated to receive either a constant infusion of remifentanil at 0.1 microg kg-1 min-1 or up-titrations to 0.2, 0.3, or 0.4 microg kg-1 min-1, respectively, 5 min before each stimulus. Subsequently, changes in heart rate and mean arterial blood pressure were recorded for 8 min. Increases exceeding 20% of baseline were considered to be of clinical relevance. Patients who exhibited these alterations were termed responders.

RESULTS

The number of responders was less with the two higher remifentanil dosages (P<0.05) while propofol target doses could either be kept at the same level or even be reduced without affecting the plane of anaesthesia. Although single phenylephrine bolus had to be applied more frequently in these two groups (P<0.05), no severe haemodynamic depression was observed.

CONCLUSIONS

Remifentanil at 0.3 and 0.4 microg kg-1 min-1 in combination with a target-controlled propofol infusion in the pre-bypass period is well tolerated. It appears to mitigate potentially hazardous haemodynamic responses from stressful stimuli equally well as higher doses when compared with data from the literature.

Magnesium moderately decreases remifentanil dosage required for pain management after cardiac surgery †

BACKGROUND

Magnesium is a calcium and an NMDA-receptor antagonist and can modify important mechanisms of nociception. We evaluated the co-analgesic effect of magnesium in the postoperative setting after on-pump cardiac surgery.

METHODS

Forty patients randomly received either magnesium gluconate as an i.v. bolus of 0.21 mmol kg(-1) (86.5 mg kg(-1)) followed by a continuous infusion of 0.03 mmol(-1) kg(-1) h(-1) (13.8 mg kg(-1) h(-1)) or placebo for 12 h after tracheal extubation. After surgery, remifentanil was decreased to 0.05 microg kg(-1) min(-1) and titrated according to a pain intensity score (PIS, range 1-6) in the intubated, awake patient and a VAS scale (range 1-100) after extubation. If PIS was > or =3 or VAS > or =30, the infusion was increased by 0.01 microg kg(-1) min(-1); if ventilatory frequency was < or =10 min(-1) it was decreased by the same magnitude.

RESULTS

Magnesium lowered the cumulative remifentanil requirement after surgery (P<0.05). PIS > or =3 was more frequent in the placebo group (P<0.05). Despite increased remifentanil demand, VAS scores were also higher in the placebo group at 8 (2 vs 8) and 9 h after extubation (2 vs 7) (P<0.05). Dose reductions attributable to a ventilatory frequency < or =10 min(-1) occurred more often in the magnesium group (17 vs 6; P<0.05). However, time to tracheal extubation was not prolonged.

CONCLUSIONS

Magnesium gluconate moderately reduced the remifentanil consumption without serious side-effects. The opioid-sparing effect of magnesium may be greater at higher pain intensities and with increased dosages.