Storage of packed red blood cells impairs an inherent coagulation property of erythrocytes.

Storage of packed red blood cells is associated with changes in erythrocytes that over time increasingly impair cellular function and potentially contribute to adverse effects associated with blood transfusion. Exposure of phosphatidylserine at the outer membrane leaflet of erythrocytes and shedding of microvesicles (MVs) during packed red blood cell storage are alterations assumed to increase the risk of prothrombotic events in recipients. Here, we used rotational thromboelastometry to study the coagulation process in blood samples with erythrocytes from stored PRBCs reconstituted with freshly prepared platelet-rich plasma. We explored the influence of following effects on the coagulation process: 1) PRBC storage duration, 2) differences between erythrocytes from stored PRBCs compared to freshly drawn erythrocytes, and 3) the contribution of added MVs. Interestingly, despite of a higher fraction of PS-positive cells, erythrocytes from PRBCs stored for 6 weeks revealed longer clotting times than samples with erythrocytes stored for 2 or 4 weeks. Further, clotting times and clot formation times were considerably increased in samples reconstituted with erythrocytes from stored PRBCs as compared to fresh erythrocytes. Moreover, MVs added to reconstituted samples elicited only comparably small and ambiguous effects on coagulation. Thus, this study provides no evidence for an amplified clotting process from prolonged storage of PRBCs but on the contrary implicates a loss of function, which may be of clinical significance in massive transfusion. Our observations add to the increasing body of evidence viewing erythrocytes as active players in the clotting process.

The effect of oral Δ-9-tetrahydrocannabinol on the minimal alveolar concentration of sevoflurane: A randomised, controlled, observer-blinded experimental study.

BACKGROUND: Cannabis has increasingly been used for medical and recreational purposes. The main pharmacological compound in cannabis is tetrahydrocannabinol (THC), which has sedative, anxiolytic and analgesic effects. In some animal models, THC has also been shown to reduce the minimum alveolar concentration (MAC) of halothane and cyclopropane, but its effect on sevoflurane, currently the most commonly used inhalational anaesthetic agent, has not been investigated. OBJECTIVE: To investigate the effect of THC on the MAC of sevoflurane in rats. METHODS: Observer-blinded, randomised controlled trial. SETTING: Centre for Biomedical Research of the Medical University of Vienna, 2019. INDIVIDUALS: Thirty-eight adult Wistar rats. INTERVENTIONS: The rats were allocated randomly into one of two groups. Group A received THC 10 mg kg and group B received the corresponding volume of placebo via gastric gavage (administration through a tube placed in the distal oesophagus). The rats were then individually anaesthetised in an airtight sevoflurane-flooded chamber, and the MAC in both groups was determined using Dixon's up-and-down method. Blood samples were drawn to measure serum concentrations of THC. MAIN OUTCOME MEASURES: The primary outcome was the MAC of sevoflurane in Groups A and B. RESULTS: The bootstrap estimate of the MAC of sevoflurane was 2.1 (95% confidence interval 1.8 to 2.4) vol% in the THC group and 2.8 (95% confidence interval 2.7 to 2.9) vol% in the placebo group, corresponding to a significant MAC reduction of 26% in response to THC. CONCLUSION: Gastric administration of THC 10 mg kg significantly reduced the MAC of sevoflurane by 26%. TRIAL REGISTRATION: Not applicable.

Duration of safe apnea in patients with morbid obesity during passive oxygenation using high-flow nasal insufflation versus regular flow nasal insufflation, a randomized trial.

BACKGROUND: Obese patients are at risk for rapid oxygen desaturation during anesthesia induction. Apneic oxygenation with regular flow oxygen insufflation has successfully been used to prolong the duration of safe apnea without desaturation (DAWD) in morbidly obese patients. Using high-flown nasal insufflation of oxygen (HFNI) for apneic oxygenation might further increase the DAWD. OBJECTIVES: To compare the duration of safe apnea using high-flown nasal insufflation of oxygen or standard flow oxygen insufflation for apneic oxygenation in a simulated difficult intubation scenario in patients with morbid obesity. SETTING: Operating room, University Hospital, Austria. METHODS: In a prospective, randomized, clinical trial, patients received standardized preoxygenation and anesthesia induction. Apneic oxygenation was performed using standard nasal prongs (10 L/min) or HFNI (120 L/min) during laryngoscopy. A Cormack-Lehane 3° view was maintained until the oxygen saturation on pulse oximetry (SpO2) dropped ≤95% or for a maximum of 15 minutes. The primary outcome of this study was to compare the duration of safe apnea using HFNI or standard flow oxygen insufflation for apneic oxygenation. In addition, arterial blood gas results, and airway pressures were investigated. RESULTS: In 40 patients with morbid obesity (body mass index [BMI] >40 kg/m2) and the American Society of Anesthesiologists physical classification ≤3 who underwent bariatric surgery, the median duration of safe apnea was 601 (268-900) seconds in the standard group and 537 (399-808) seconds in the HFNI group (P = .698). No differences in arterial blood gas results were observed between the groups. The median airway pressure was 0 (0-0) cm H2O in the standard group and 1 (0-2) cm H2O in the HFNI group (P = .005). CONCLUSION: Compared with standard nasal apneic oxygenation, HFNI did not increase the duration of safe apnea in patients with morbid obesity. A significant but clinically negligible higher airway pressure was observed when using HFNI.

Education of medical personnel optimizes filling volume of blood culture bottles without negatively affecting microbiology testing.

BACKGROUND: Anemia is a risk factor for adverse outcomes, which can be aggravated by unnecessary phlebotomies. In blood culture testing, up to 30 ml of blood can be withdrawn per sample, even though most manufacturers recommend blood volumes of 10 ml or less. After assessing the filling volume of blood culture bottles at our institution, we investigated whether an educational intervention could optimize filling volume of blood culture bottles without negatively affecting microbiology testing. METHODS: We weighed 10,147 blood cultures before and 11,806 blood cultures after a six-month educational intervention, during which employees were trained regarding correct filling volume via lectures, handouts, emails, and posters placed at strategic places. RESULTS: Before the educational intervention, only 31% of aerobic and 34% of anaerobic blood cultures were filled correctly with 5-10 ml of blood. The educational intervention increased the percentage of correctly filled bottles to 43% (P < 0.001) for both aerobic and anaerobic samples without negatively affecting results of microbiologic testing. In addition, sample volume was reduced from 11.0 ± 6.5 to 9.4 ± 5.1 ml (P < 0.001) in aerobic bottles and from 10.1 ± 5.6 to 8.8 ± 4.8 ml (P < 0.001) in anaerobic bottles. CONCLUSION: Education of medical personnel is a simple and effective way to reduce iatrogenic blood loss and possibly moderate the extent of phlebotomy-induced anemia.

Thromboelastometry in patients with advanced chronic liver disease stratified by severity of portal hypertension.

BACKGROUND: Rotational thromboelastometry (ROTEM) has been studied in patients with advanced chronic liver disease (ACLD) without considering the impact of portal hypertension. We evaluated the influence of the hepatic venous pressure gradient (HVPG) on ROTEM results in patients with ACLD. METHODS: Cross-sectional study; ACLD patients undergoing HVPG measurement within the prospective Vienna Cirrhosis Study (NCT03267615) underwent concomitant ROTEM testing. RESULTS: Among 159 patients (68% male; Child-Pugh-A: 53%, Child-Pugh-B: 34%, Child-Pugh-C: 13%), 21 patients (13%) had a HVPG between 6 and 10 mmHg, 84 patients (53%) between 10 and 19 mmHg, and 54 patients (34%) ≥ 20 mmHg. Child-Pugh-C patients (vs. Child-Pugh-A and vs. Child-Pugh-B patients, respectively) showed longer clot formation time (CFT: median 187 s vs. 122 s vs. 122 s, p = 0.007) and lower maximum clot firmness (MCF: median: 45 mm vs. 56 mm vs. 56 mm, p = 0.002) in extrinsic thromboelastometry (EXTEM), while platelet counts were similar across Child-Pugh stages. In the overall cohort, ROTEM parameters did not differ by severity of portal hypertension. However, among compensated Child-Pugh-A patients, MCF decreased with increasing portal pressure, i.e. in higher HVPG strata (HVPG 9-10 mmHg: median MCF: 59 mm vs. HVPG 10-19 mmHg: 56 mm vs HVPG ≥ 20 mmHg: 54 mm, p = 0.023). Furthermore, patients with short CFT and high MCF in EXTEM had higher levels of lipopolysaccharide-binding protein, C-reactive protein, and procalcitonin, as well as higher leukocyte counts (all p < 0.05). CONCLUSIONS: Portal hypertension seems to impact ROTEM results only in compensated Child-Pugh-A patients. Bacterial translocation and systemic inflammation may trigger a procoagulant state in patients with ACLD.

Regulation of histamine and diamine oxidase in patients undergoing orthotopic liver transplantation.

Increased concentrations of the vasodilator histamine have been observed in patients undergoing abdominal surgery. The role of histamine during orthotopic liver transplantation (OLT) has only been studied in animals. The aim of this study was to measure plasma concentrations of histamine and its degrading enzyme diamine oxidase (DAO) in patients undergoing orthotopic liver transplantation, and assess whether histamine or DAO correlate with intraoperative noradrenaline requirements. Histamine and DAO concentrations were measured in 22 adults undergoing liver transplantation and 22 healthy adults. Furthermore, norepinephrine requirements during liver transplantation were recorded. Baseline concentrations of histamine and DAO were greater in patients, who underwent liver transplantation, than in healthy individuals (Histamine: 6.4 nM, IQR[2.9-11.7] versus 4.3 nM, IQR[3.7-7.1], p = 0.029; DAO: 2.0 ng/mL, IQR[1.5-4.1] versus <0,5 ng/mL, IQR[<0.5-1.1], p < 0.001). During liver transplantation, histamine concentrations decreased to 1.8 nM, IQR[0.5-4.9] in the anhepatic phase (p < 0.0001 versus baseline), and to 1.5 nM, IQR[0.5-2.9] after reperfusion (p < 0.0001 versus baseline). In contrast, DAO concentrations increased to 35.5 ng/ml, IQR[20-50] in the anhepatic phase (p = 0.001 versus baseline) and to 39.5 ng/ml, IQR[23-64] after reperfusion (p = 0.001 versus baseline), correlating inversely with histamine. Norepinephrine requirements during human liver transplantation correlated significantly with DAO concentrations in the anhepatic phase (r = 0.58, p = 0.011) and after reperfusion (r = 0.56; p = 0.022). In patients undergoing orthotopic liver transplantation, histamine concentrations decrease whereas DAO concentrations increase manifold. Diamine oxidase correlates with intraoperative norepinephrine requirements in patients undergoing OLT.

Glycocalyx Damage Within Human Liver Grafts Correlates With Graft Injury and Postoperative Graft Function After Orthotopic Liver Transplantation.

BACKGROUND: Destruction of the endothelial glycocalyx has been observed within lung and kidney grafts during ischemic organ preservation. We aimed to quantify glycocalyx damage within human liver grafts after organ preservation and correlate the results with graft injury and postoperative graft function in patients undergoing orthotopic liver transplantation (OLT). METHODS: Syndecan-1 (Sdc-1) was measured as indicator of glycocalyx degradation in effluents of 38 liver grafts and serum of patients undergoing OLT. Effluent Sdc-1 concentrations were correlated with hepatic injury markers from the effluent. Furthermore, we assessed the association of Sdc-1 with early allograft dysfunction (EAD), 1-year graft survival, and 1-year patient survival. RESULTS: Effluent Sdc-1 concentrations correlated with effluent concentrations of hepatocellular injury markers, including alkaline phosphatase (R = 0.543, P = 0.003), aspartate aminotransferase (R = 0.420, P = 0.029), and lactate (R = 0.574, P = 0.002). Sdc-1 effluent concentrations were greater in patients who developed EAD compared with those without EAD (4720 [4374-5133] vs 3838 [3202-4240] ng/mL, P = 0.015). Furthermore, receiver operating characteristics analyses revealed that effluent Sdc-1 concentrations (AUC = 0.82, P = 0.017) and serum Sdc-1 concentrations (AUC = 0.84, P = 0.006) were associated with the development of EAD. These results were confirmed by regression analyses. No association was found between Sdc-1 and 1-year graft survival or 1-year patient survival. CONCLUSIONS: Our data suggest that the glycocalyx is damaged within human liver grafts during preservation and the extent of glycocalyx damage correlates with the severity of hepatocellular injury. Recipients of livers grafts with greater glycocalyx damage might be at higher risk for development of EAD after OLT.

Urinary [TIMP-2] × [IGFBP-7] for predicting acute kidney injury in patients undergoing orthotopic liver transplantation.

BACKGROUND: The product of the concentrations of urinary tissue inhibitor of metalloproteinases-2 and insulin-like growth factor binding protein-7 (urinary [TIMP-2] × [IGFBP-7]) has been suggested as biomarker for early detection of acute kidney injury (AKI) in various clinical settings. However, the performance of urinary [TIMP-2] × [IGFBP-7] to predict AKI has never been assessed in patients undergoing orthotopic liver transplantation (OLT). Thus, the aim of this study was to assess the early predictive value of urinary [TIMP-2] × [IGFBP-7] for the development of AKI after OLT. METHODS: In this observational study, urinary [TIMP-2] × [IGFBP-7] was measured in samples from adult OLT patients. AKI was diagnosed and classified according to KDIGO criteria. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of urinary [TIMP-2] × [IGFBP-7] for the development of AKI. RESULTS: Forty patients (mean age 55 ± 8 years) were included. Twenty-eight patients (70%) developed AKI stage 1, 2, or 3 within 48 h after OLT. Urinary [TIMP-2] × [IGFBP-7] was not predictive for AKI at the end of OLT (AUC: 0.54, CI [0.32-0.75], P = 0.72), at day 1 (AUC: 0.60, CI [0.41-0.79], P = 0.31), or day 2 after OLT (AUC: 0.63, CI [0.46-0.8], P = 0.18). CONCLUSION: Based on our results, routine clinical use of urinary [TIMP-2] × [IGFBP-7] cannot be recommended for risk assessment of AKI in patients undergoing OLT.

Transfusion of standard-issue packed red blood cells induces pulmonary vasoconstriction in critically ill patients after cardiac surgery-A randomized, double-blinded, clinical trial.

BACKGROUND: Experimental and volunteer studies have reported pulmonary vasoconstriction during transfusion of packed red blood cells (PRBCs) stored for prolonged periods. The primary aim of this study was to evaluate whether transfusion of PRBCs stored over 21 days (standard-issue, siPRBCs) increases pulmonary artery pressure (PAP) to a greater extent than transfusion of PRBCs stored for less then 14 days (fresh, fPRBCs) in critically ill patients following cardiac surgery. The key secondary aim was to assess whether the pulmonary vascular resistance index (PVRI) increases after transfusion of siPRBCs to a greater extent than after transfusion of fPRBCs. METHODS: The study was performed as a single-center, double-blinded, parallel-group, randomized clinical trial. Leukoreduced PRBCs were transfused while continuously measuring hemodynamic parameters. Systemic concentrations of syndecan-1 were measured to assess glycocalyx injury. After randomizing 19 patients between January 2014 and June 2016, the study was stopped due to protracted patient recruitment. RESULTS: Of 19 randomized patients, 11 patients were transfused and included in statistical analyses. Eight patients were excluded prior to transfusion, 6 patients received fPRBCs (10±3 storage days), whereas 5 patients received siPRBCs (33±4 storage days). The increase in PAP (7±3 vs. 2±2 mmHg, P = 0.012) was greater during transfusion of siPRBCs than during transfusion of fPRBCs. In addition, the change in PVRI (150±89 vs. -4±37 dyn·s·cm-5·m2, P = 0.018) was greater after transfusion of siPRBCs than after transfusion of fPRBCs. The increase in PAP correlated with the change of systemic syndecan-1 concentrations at the end of transfusion (R = 0.64,P = 0.034). CONCLUSION: Although this study is underpowered and results require verification in larger clinical trials, our findings suggest that transfusion of siPRBCs increases PAP and PVRI to a greater extent than transfusion of fPRBCs in critically ill patients following cardiac surgery. Glycocalyx injury might contribute to pulmonary vasoconstriction associated with transfusion of stored blood.

D-dopachrome tautomerase predicts outcome but not the development of acute kidney injury after orthotopic liver transplantation.

BACKGROUND: Elevated concentrations of D-dopachrome tautomerase (D-DT) were associated with adverse outcome in various clinical settings. However, no study assessed D-DT concentrations in patients requiring orthotopic liver transplantation (OLT). The aim of this observational study was to measure serum D-DT concentrations in patients undergoing OLT and associate D-DT with survival and acute kidney injury (AKI). METHODS: Forty-seven adults with end-stage liver disease undergoing OLT were included. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of D-DT for outcome and AKI after OLT. Survival was analyzed by Kaplan-Meier curves. RESULTS: Serum D-DT concentrations were greater in non-survivors than in survivors prior to OLT (86 [50-117] vs. 53 [31-71] ng/ml, P = 0.008), and on day 1 (357 [238-724] vs. 189 [135-309] ng/ml, P = 0.001) and day 2 (210 [142-471] vs. 159 [120-204] ng/ml, P = 0.004) following OLT. Serum D-DT concentrations predicted lethal outcome when measured preoperatively (AUC = 0.75, P = 0.017) and on postoperative day 1 (AUC = 0.75, P = 0.015). One-year survival of patients with preoperative D-DT concentrations >85 ng/ml was 50%, whereas that of patients with preoperative D-DT concentrations <85 ng/ml was 83% (Chi2 = 5.83, P = 0.016). In contrast, D-DT was not associated with AKI after OLT. CONCLUSION: In patients undergoing OLT, serum D-DT might predict outcome after OLT.

Outcome after liver transplantation in elderly recipients (>65 years) - A single-center retrospective analysis.

BACKGROUND: Liver transplantation (LT) in elderly recipients is controversially discussed in the literature with only little data on long-term outcome available. We aimed to evaluate the safety and efficiency of LT in elderly recipients (>65 years). METHODS: Between 1989-2016, 139 patients >65 years-old were listed for liver transplantation, and 76 (55%) were transplanted. Patient outcome and characteristics were evaluated separately for the time period before (1989-2004) and after (2005-2016) MELD-implementation. Post-transplant outcome was compared between the elderly cohort and LT-recipients aged 18-65 years (n = 1395). RESULTS: Overall survival of patients >65 years was better in the MELD-era compared to the earlier period (1- and 5-year-survival: 73%, 60% vs. 69%, 37%, respectively; p = 0.055). The main differences between the two groups included higher recipient age (p = 0.001) and BMI (p = 0.001), higher donor age (p < 0.001), less need of intraoperative red blood cells (p = 0.008) and a lower number of postoperative rejections (p = 0.03) after 2004. Comparing the overall survival of patients transplanted in the MELD-era aged 18-65 years vs. >65 years displayed comparable 1- and 5 year-survival rates (81%, 68% vs. 73% and 60%, respectively, p = 0.558). CONCLUSION: In the modern era, outcome of patients receiving LT with >65 years is comparable to <65 year-old patients. After careful evaluation, patients >65 years old should be considered for LT.

Comparison of macrophage migration inhibitory factor and neutrophil gelatinase-associated lipocalin-2 to predict acute kidney injury after liver transplantation: An observational pilot study.

INTRODUCTION: Several biomarkers have been suggested as early predictors of acute kidney injury (AKI) after orthotopic liver transplantation (OLT). Neutrophil gelatinase-associated lipocalin-2 (NGAL) appears to be a promising predictor of AKI after OLT, but the clinical benefit remains to be proven. Recently, systemic macrophage migration inhibitory factor (MIF) has been proposed as early indicator for requirement of renal replacement therapy after OLT. The aim of this prospective, observational pilot study was to compare the predictive values of serum and urinary MIF for severe AKI after OLT to those of serum and urinary NGAL. METHODS: Concentrations of MIF and NGAL were measured in serum and urine samples collected from patients undergoing OLT. Acute kidney injury was classified according to the KDIGO criteria, with stages 2 and 3 summarized as severe AKI. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of MIF and NGAL for the development of severe AKI. RESULTS: Forty-five patients (mean age 55±8 years) were included. Nineteen patients (38%) developed severe AKI within 48 hours after reperfusion. At the end of OLT, serum MIF was predictive of severe AKI (AUC 0.73; 95% confidence intervals, CI 0.55-0.90; P = 0.03), whereas urinary MIF, serum NGAL, and urinary NGAL were not. On the first postoperative day, serum MIF (AUC 0.78; CI 0.62-0.93; P = 0.006), urinary MIF (AUC 0.71; CI 0.53-0.88; P = 0.03), and urinary NGAL (AUC 0.79; CI 0.64-0.93; P = 0.02) were predictive for severe AKI, while serum NGAL was not. CONCLUSION: In the setting of OLT, MIF and NGAL had similar predictive values for the development of severe AKI.

Patients Undergoing Orthotopic Liver Transplantation Require Lower Concentrations of the Volatile Anesthetic Sevoflurane.

BACKGROUND: Sevoflurane is a volatile anesthetic commonly used to maintain anesthesia in patients with end-stage liver disease (ESLD) undergoing orthotopic liver transplantation (OLT). Growing evidence suggests that patients with ESLD have decreased anesthetic requirements compared to patients with preserved liver function. The potency of volatile anesthetics is expressed as the minimum alveolar concentration (MAC). In this prospective, blinded study, we compared the MAC of sevoflurane among patients with ESLD undergoing OLT and patients with normal liver function undergoing major abdominal surgery. METHODS: After propofol-induced anesthesia, the MAC of sevoflurane was assessed by evaluating motor response to initial skin incision in patients undergoing OLT and in patients with normal liver function undergoing major abdominal surgery. The MAC was determined using Dixon "up-and-down" method and compared between groups. In addition, the bispectral index was documented immediately before and after skin incision. RESULTS: Twenty patients undergoing OLT and 20 control patients were included in the study. The MAC of sevoflurane in patients undergoing OLT was 1.3% (95% confidence interval [CI], 1.1-1.4). In comparison, the MAC of sevoflurane in patients with normal liver function was 1.7% (95% CI, 1.6-1.9), equal to a relative reduction of the MAC in patients with ESLD of 26% (95% CI, 14-39). The bispectral index was higher in patients with ESLD than in control patients at 3 minutes before (47 [95% CI, 40-53] vs 35 [95% CI, 31-40], P = .011), 1 minute before (48 [95% CI, 42-54] vs 37 [95% CI, 33-43], P = .03), and 1 minute after skin incision (57 [95% CI, 50-64] vs 41 [95% CI, 36-47], P < .001). CONCLUSIONS: Our results suggest that the MAC of sevoflurane is lower in patients with ESLD than in patients with normal liver function after propofol-induced anesthesia. However, as we did not measure propofol concentrations at the time of skin incision, the difference in MAC should be interpreted with caution given that residual propofol may have been present at the time of skin incision.

Graft-derived macrophage migration inhibitory factor correlates with hepatocellular injury in patients undergoing liver transplantation.

Experimental studies suggest that macrophage migration inhibitory factor (MIF) mediates ischemia/reperfusion injury during liver transplantation. This study assessed whether human liver grafts release MIF during preservation, and whether the release of MIF is proportional to the extent of hepatocellular injury. Additionally, the association between MIF and early allograft dysfunction (EAD) after liver transplantation was evaluated. Concentrations of MIF, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatine kinase (CK) were measured in effluents of 38 liver grafts, and in serum of recipients. Concentrations of MIF in the effluent were greater than those in the recipients' serum before and after reperfusion (58 [interquartile range, IQR:23-79] µg/mL vs 0.06 [IQR:0.03-0.07] µg/mL and 1.3 [IQR:0.7-1.8] µg/mL, respectively; both P<.001). Effluent MIF concentrations correlated with effluent concentrations of the cell injury markers ALT (R=.51, P<.01), AST (R=.51, P<.01), CK (R=.45, P=.01), and LDH (R=.56, P<.01). Patients who developed EAD had greater MIF concentrations in effluent and serum 10 minutes after reperfusion than patients without EAD (Effluent: 80 [IQR:63-118] µg/mL vs 36 [IQR:20-70] µg/mL, P=.02; Serum: 1.7 [IQR:1.2-2.5] µg/mL vs 1.1 [IQR:0.6-1.7] µg/mL, P<.001). CONCLUSION: Human liver grafts release MIF in proportion to hepatocellular injury. Greater MIF concentrations in effluent and recipient's serum are associated with EAD after liver transplantation.