Mycobacterium chimaera in heater-cooler units used during cardiac surgery - growth and decontamination.

BACKGROUND: Previous studies have identified patients infected with Mycobacterium chimaera (M. chimaera) subsequent to cardiac surgery. Water tanks in heater-cooler units (HCUs) used cardiac heart surgery was traced as source. The aim was to investigate occurrence of M. chimaera and other microorganisms in HCUs and evaluate the silver-ion cleaning routine. METHOD: Five HCUs were disinfected with silver-ions and examined for mycobacteria directly (15 min) after the disinfection procedures and later on three occasions (3, 6, 10 weeks). One HCU was selected for additional investigation of the presence of other microorganisms. In addition, tap water from five sinks in the surgical department was examined for the presence of mycobacteria and other microorganisms. RESULTS: M. chimaera grew in all the HCU water tanks and in 35 of the 40 HCU samples. Three of the samples also contained Mycobacterium gordonae. When the selected HCU tanks were analysed directly after the disinfection procedure bacteria and fungi were found but no non-fermenting Gram-negative rods. These HCU samples contained a doubled to 3 fold amount of bacteria compared to initial tap water samples. No mycobacteria were found in any sample from the five water taps. CONCLUSION: The silver-ion cleaning routine was insufficient and M. chimaera was found in all HCUs. However, no mycobacteria were found in any sample from the five water taps suggesting another source of colonization. It is probable that residual water and biofilm are of importance. Our results emphasize the need for improved disinfection procedures and improved construction of the HCUs.

Retransfusion of cardiotomy suction blood impairs haemostasis: ex vivo and in vivo studies.

OBJECTIVES: Cardiotomy suction blood in volumes corresponding to 10-20% of the systemic blood volume is retransfused during cardiopulmonary bypass. We hypothesized that retransfusion of unwashed cardiotomy suction blood influences coagulation and platelet function. DESIGN: Systemic blood samples collected during cardiopulmonary bypass were supplemented ex vivo with autologous wound blood (5, 10 and 20%, respectively). Clot formation and platelet function were assessed with thromboelastometry and platelet aggregometry. In an in vivo pilot study 30 patients were randomized into a retransfusion and a no-retransfusion group. Clot formation, platelet aggregability and thrombin generation capacity were compared between the groups. RESULTS: Cardiotomy suction blood had markedly impaired clot stability and reduced levels of fibrinogen and platelets compared with systemic blood. Ex vivo addition of 10% and 20% suction blood to systemic blood impaired platelet aggregability and clot stability. Retransfusion of small amounts of wound blood in vivo (mean volume 280 ml, corresponding to 5% of the blood volume) did not significantly influence haemostasis. CONCLUSIONS: The ex vivo results suggest that addition of unwashed cardiotomy suction blood in clinically relevant volumes impairs systemic haemostasis. Retransfusion of smaller volumes in vivo has no or limited impact. Avoiding retransfusion of larger amounts of unwashed cardiotomy suction may improve postoperative haemostasis.

Cell salvage of cardiotomy suction blood improves the balance between pro- and anti-inflammatory cytokines after cardiac surgery.

OBJECTIVES: The inflammatory response after cardiac surgery is characterized by a profound release of pro- and anti-inflammatory cytokines. Recent data suggest that the balance between pro- and anti-inflammatory cytokines is of greater importance than the absolute levels. Retransfusion of unwashed cardiotomy suction blood contributes to the inflammatory response, but the balance between pro- and anti-inflammatory cytokines in cardiotomy suction blood and whether cell salvage before retransfusion influences the systemic balance have not been investigated previously. METHODS: Twenty-five coronary artery bypass grafting patients were randomized to either cell salvage of cardiotomy suction blood or no cell salvage before retransfusion. Plasma levels of three anti-inflammatory cytokines [interleukin (IL)-1 receptor antagonist, IL-4 and IL-10] and two proinflammatory cytokines (tumour necrosis factor-alpha and IL-6), and the IL-6-to-IL-10 ratio was measured in cardiotomy suction blood before and after cell salvage, and in the systemic circulation before, during and after surgery. RESULTS: Plasma levels of all cytokines except IL-4 and IL-10 were significantly higher in cardiotomy suction blood than in the systemic circulation. The IL-6-to-IL-10 ratio was 6-fold higher in cardiotomy suction blood than in the systemic circulation [median 10.2 (range 1.1-75) vs 1.7 (0.2-24), P < 0.001]. Cell salvage reduced plasma levels of cytokines in cardiotomy suction blood and improved the systemic IL-6-to-IL-10 ratio 24 h after surgery [median 5.2 (3.6-17) vs 12.4 (4.9-31)] compared with no cell salvage (P = 0.032). CONCLUSIONS: The balance of pro- and anti-inflammatory cytokines in cardiotomy suction blood is unfavourable. Cell salvage reduces the absolute levels of both pro- and anti-inflammatory cytokines in cardiotomy suction blood and improves the balance in the systemic circulation after surgery.

Hemodynamic effects of cardiotomy suction blood.

OBJECTIVE: Cardiac surgery induces a systemic inflammatory activation, which in severe cases is associated with peripheral vasodilation and hypotension. Cardiotomy suction blood contains high levels of inflammatory mediators, but the effect of cardiotomy suction blood on the vasculture is unknown. We investigated the effect of cardiotomy suction blood on systemic vascular resistance in vivo and whether cell-saver processing of suction blood affects the vascular response. METHODS: Twenty-five patients undergoing coronary surgery (mean age, 68 +/- 2 years; 80% men) were included in a prospective randomized study. The patients were randomized to retransfusion of cell-saver processed (n = 13) or cell-saver unprocessed (n = 12) suction blood during full cardiopulmonary bypass. Mean arterial blood pressure was continuously registered during retransfusion, and systemic vascular resistance was calculated. Plasma concentrations of tumor necrosis factor alpha, interleukin 6, and complement factor C3a were measured in suction blood. RESULTS: Retransfusion of cardiotomy suction blood induced a transient reduction in systemic vascular resistance in all patients. The peak reduction was significantly less pronounced in the group receiving cell-saver processed blood (-12% +/- 2% vs -28% +/- 3%, P = .001). There was a significant correlation between tumor necrosis factor alpha concentration in retransfused cardiotomy suction blood and peak reduction of systemic vascular resistance (r = 0.60, P = .002). CONCLUSIONS: The results suggest cardiotomy suction blood is vasoactive and might influence vascular resistance and blood pressure during cardiac surgery. The observed vasodilation is proportional to the inflammatory activation of suction blood and can be reduced by processing suction blood with a cell-saving device before retransfusion.

A closed perfusion system with heparin coating and centrifugal pump improves cardiopulmonary bypass biocompatibility in elderly patients.

BACKGROUND: Cardiopulmonary bypass induces a systemic inflammatory and hemostatic activation, which may contribute to postoperative complications. Our aim was to compare the inflammatory response, coagulation, and fibrinolytic activation between two different perfusion systems: one theoretically more biocompatible with a closed-circuit, complete heparin coating, and a centrifugal pump, and one conventional system with uncoated circuit, roller pump, and a hard-shell venous reservoir. METHODS: Forty-one elderly patients (mean age, 73 +/- 1 years, 66% men) undergoing coronary artery bypass grafting or aortic valve replacement were included in a prospective, randomized study. Plasma concentrations of complement factors (C3a, C4d, Bb, and sC5b-9), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-8), granulocyte degradation products (polymorphonuclear elastase), and markers of coagulation (thrombin-antithrombin) and fibrinolysis (D-dimer, tissue plasminogen activator antigen and tissue plasminogen activator-plasminogen activator inhibitor-1 complex) were measured preoperatively, at bypass during rewarming (35 degrees C), 60 minutes after bypass, and on day 1 after surgery. RESULTS: The mean concentrations of C3a (-39%; p = 0.008), Bb (-38%; p < 0.001), sC5b-9 (-70%; p < 0.001), interleukin-8 (-60%; p = 0.009), polymorphonuclear-elastase (-55%; p < 0.003), and tissue plasminogen activator antigen (-51%; p = 0.012) were all significantly lower in the biocompatible group during rewarming. Sixty minutes after bypass, the mean concentrations of sC5b-9 (-39%; p = 0.006) and polymorphonuclear-elastase (-55%; p < 0.001) were lower in the biocompatible group. CONCLUSIONS: The results suggest that a closed perfusion system with a heparin-coated circuit and a centrifugal pump may improve cardiopulmonary bypass biocompatibility in elderly cardiac surgery patients in comparison with a conventional system.

Tumor necrosis factor gene polymorphisms and inflammatory response in coronary artery bypass grafting patients.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha), a key factor in the inflammatory cascade, has been implicated in coronary artery disease. Two biallelic polymorphisms in the TNF gene locus (TNFA at position -308 and TNFB at +252) may influence TNF-alpha production. Individuals with the rare TNFA2 allele or TNFB2 homozygosity have augmented TNF-alpha production. We investigated the genotypes associated with increased TNF-alpha production in coronary artery bypass grafting (CABG) patients and if these genotypes influence the magnitude of the postoperative inflammatory response. METHODS: TNF gene polymorphisms were analyzed by multiplex fluorescent solid-phase minisequencing in 86 CABG patients. Plasma concentrations of TNF-alpha, IL-6 and C3a and C-reactive protein (CRP) were analyzed before and after surgery in 45 of the patients and compared with genetically high and low TNF-alpha producers. RESULTS: Thirty percent of the patients carried the TNFA2 allele and 45% were TNFB2 homozygous. The allelic frequencies were TNFA1/TNFA2 = 0.84/0.16 and TNFB1/TNFB2 = 0.32/0.68. Pre- and postoperative levels of TNF-alpha, IL-6, C3a and CRP did not differ significantly between genetically high and low TNF-alpha producers. CONCLUSIONS: The frequency of high TNF-alpha producing genotypes in a CABG population was comparable to that previously reported from normal populations. Furthermore, we found no evidence that the investigated TNF-alpha gene polymorphisms influence postoperative inflammatory response after uncomplicated coronary surgery.

Coronary surgery without cardiotomy suction and autotransfusion reduces the postoperative systemic inflammatory response.

BACKGROUND: Cardiotomy suction and autotransfusion of mediastinal shed blood may contribute to the inflammatory response after cardiac surgery. We compared inflammatory activation, myocardial injury, bleeding, and hemoglobin levels in patients undergoing coronary surgery with or without retransfusion of cardiotomy suction blood and mediastinal shed blood. METHODS: Twenty-nine patients were included in a prospective randomized study. Cardiotomy suction blood and mediastinal shed blood were either retransfused or discarded. Plasma concentrations of the cytokines tumor necrosis factor-alpha and interleukin-6 and complement factor C3a were measured preoperatively and 10 minutes, 2 hours, and 24 hours after cardiopulmonary bypass. C-reactive protein, erythrocyte sedimentation rate, troponin-T, and hemoglobin levels were analyzed preoperatively, and 24 and 48 hours after cardiopulmonary bypass. Postoperative bleeding the first 12 hours was registered. RESULTS: Baseline data did not differ between the groups. Plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and C3a increased after surgery in both groups but significantly less in the group without cardiotomy suction and autotransfusion. The peak delta values in the no-retransfusion group was 36% (tumor necrosis factor-alpha), 47% (interleukin-6), and 75% (C3a) of the values in the retransfusion group. C-reactive protein, erythrocyte sedimentation rate, and troponin-T increased after surgery in both groups without intergroup differences. Postoperative bleeding and hemoglobin levels did not differ between the groups. No patient received homologous blood transfusion. CONCLUSIONS: Coronary surgery without retransfusion of cardiotomy suction blood and mediastinal shed blood reduces the postoperative systemic inflammatory response.

Tumor necrosis factor gene polymorphisms and inflammatory response in coronary artery bypass grafting patients.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha), a key factor in the inflammatory cascade, has been implicated in coronary artery disease. Two biallelic polymorphisms in the TNF gene locus (TNFA at position -308 and TNFB at +252) may influence TNF-alpha production. Individuals with the rare TNFA2 allele or TNFB2 homozygosity have augmented TNF-alpha production. We investigated the genotypes associated with increased TNF-alpha production in coronary artery bypass grafting (CABG) patients and if these genotypes influence the magnitude of the postoperative inflammatory response. METHODS: TNF gene polymorphisms were analyzed by multiplex fluorescent solid-phase minisequencing in 86 CABG patients. Plasma concentrations of TNF-alpha, IL-6 and C3a and C-reactive protein (CRP) were analyzed before and after surgery in 45 of the patients and compared with genetically high and low TNF-alpha producers. RESULTS: Thirty percent of the patients carried the TNFA2 allele and 45% were TNFB2 homozygous. The allelic frequencies were TNFA1/TNFA2=0.84/0.16 and TNFB1/TNFB2=0.32/0.68. Pre- and postoperative levels of TNF-alpha, IL-6, C3a and CRP did not differ significantly between genetically high and low TNF-alpha producers. CONCLUSIONS: The frequency of high TNF-alpha producing genotypes in a CABG population was comparable to that previously reported from normal populations. Furthermore, we found no evidence that the investigated TNF-alpha gene polymorphisms influence postoperative inflammatory response after uncomplicated coronary surgery.