Heparin algorithm for anticoagulation during continuous renal replacement therapy

Efficacy of Hemoperfusion in Severe and Critical Cases of COVID-19

INTRODUCTION

Uncontrolled overproduction of inflammatory mediators is predominantly observed in patients with severe COVID-19. The excessive immune response gives rise to multiple organ dysfunction. Implementing extracorporeal therapies may be useful in omitting inflammatory mediators and supporting different organ systems. We aimed to investigate the effectiveness of hemoperfusion in combination with standard therapy in critically ill COVID-19 patients.

METHOD

We conducted a single-center, matched control retrospective study on patients with confirmed SARS-CoV-2 infection. Patients were treated with hemoperfusion in combination with standard therapy (hemoperfusion group) or standard treatment (matched group). Hemoperfusion or hemoperfusion and continuous renal replacement therapies were initiated in the hemoperfusion group. The patients in the matched group were matched one by one with the hemoperfusion group for age, sex, oxygen saturation (SPO2) at the admission, and the frequency of using invasive mechanical ventilation during hospitalization. Two types of hemoperfusion cartridges used in this study were Jafron© (HA330) and CytoSorb® 300.

RESULT

A total of 128 COVID-19-confirmed patients were enrolled in this study; 73 patients were allotted to the matched group and 55 patients received hemoperfusion. The median SPO2 at the admission day in the control and hemoperfusion groups was 80% and 75%, respectively (p value = 0.113). The mortality rate was significantly lower in the hemoperfusion group compared to the matched group (67.3% vs. 89%; p value = 0.002). The median length of ICU stay was statistically different in studied groups (median, 12 days for hemoperfusion group vs. 8 days for the matched group; p < 0.001). The median final SPO2 was statistically higher in the hemoperfusion group than in the matched group, and the median PaCO2 was lower.

CONCLUSION

Among critically ill COVID-19 patients, based on our study, the use of hemoperfusion may reduce the mortality rate and improve SPO2 and PaCO2.

Anticoagulation strategies in continuous renal replacement therapy

The most common anticoagulant options for continuous renal replacement therapy (CRRT) include unfractionated heparin (UFH), regional citrate anticoagulation (RCA), and no anticoagulation. Less common anticoagulation options include UFH with protamine reversal, low-molecular weight heparin (LMWH), thrombin antagonists, and platelet inhibiting agents. The choice of anticoagulant for CRRT should be determined by patient characteristics, local expertise, and ease of monitoring. The Kidney Disease Improving Global Outcomes (KDIGO) acute kidney injury guidelines recommend using RCA rather than UFH in patients who do not have contraindications to citrate and are with or without increased risk of bleeding. Monitoring should include evaluation of the anticoagulant effect, circuit life, filter efficacy, and complications.

Monitoring Anticoagulation with Unfractionated Heparin on Renal Replacement Therapy. Which is the Best aPTT Sampling Site?

BACKGROUND

Controlled anticoagulation is key to maintaining continuous blood filtration therapies. Objective: The study aimed to compare different blood sampling sites for activated partial thromboplastin time (aPTT) to evaluate anticoagulation with unfractionated heparin (UFH) in continuous renal replacement therapy (CRRT) and identify the most appropriate sampling site for safe patient anticoagulation and increased filter life span.

METHOD

The study was a prospective observational single-centre investigation targeting intensive care unit (ICU) patients on CRRT using an anticoagulation protocol based on patient characteristics and a weight-based modified nomogram. Eighty-four patients were included in the study. Four sampling sites were assessed: heparin free central venous nondialysis catheter (CVC), an arterial line with heparinised flush (Artery), a circuit access line (Access), and a circuit return line (Postfilter). Blood was sampled from each of four different sites on every patient, four hours after the first heparin bolus. aPTT was determined using a rapid clot detector, point of care device.

RESULTS

A high positive correlation was obtained for aPTT values between CVC and Access sampling sites (r (84) =0.72; p <0 .05) and a low positive correlation between CVC and Arterial sampling site (r (84) =0.46, p < 0.05). When correlated by artery age, the young Artery (1-3 day old) correlates with CVC, Access and Postfilter (r (45) = 0.74, p >0.05). The aPTT values were significantly higher at Postfilter and Arterial sampling site, older than three days, compared to the CVC sampling site (p<0.05).

CONCLUSION

Considering patient bleeding risks and filter life span, the optimal sampling sites for safe assessment of unfractionated heparin anticoagulation on CRRT during CVVHDF were the central venous catheter using heparin free lavage saline solution, a heparinised flushed arterial catheter not older than three days, and a circuit access line.

Anemia, Blood Transfusion, and Filter Life Span in Critically Ill Patients Requiring Continuous Renal Replacement Therapy for Acute Kidney Injury: A Case-Control Study

Background

Filter clotting is frequent during continuous renal replacement therapy (CRRT), which increases anemia risk. We studied anemia and blood transfusion in critically ill patients requiring CRRT for acute kidney injury and assessed the relationship between CRRT filter life span and PRBC transfusion.

Methods

A case-control study was conducted at a tertiary-care intensive care unit (ICU) where CRRT cases were matched with controls for age, gender, admission category, and severity of illness. Daily hemoglobin levels, blood transfusions, and life span of CRRT filter were noted. CCRT patients were categorized according to the median of the filter life span (20 hours).

Results

Ninety-five cases and 102 controls were enrolled. The hemoglobin level on admission was similar in the two groups, yet cases had significantly lower hemoglobin levels than controls (72.8 ± 15.3 versus 82.5 ± 20.7 g/L, p < 0.001) during ICU stay. Anemia <70 g/L occurred in 50% of cases and 19% of controls (p < 0.001). Most (56.3%) cases were transfused compared with 29.9% for controls (p < 0.001) with higher number of transfused packed red blood cell (PRBC) units in cases (2.6 ± 4.0 versus 1.5 ± 3.2 units per patient, p=0.03). Patients with shorter versus longer filter life had similar hemoglobin level in the first 7 days of CRRT with no difference in PRBC transfusion requirement. Prefilter heparin use and hemodialysis access location were not associated with longer filter life span. The mortality was similar in patients with shorter versus longer filter life.

Conclusions

CRRT in ICU was associated with larger drop in hemoglobin and more PRBC transfusion. Shorter (<20 hours) versus longer CCRT filter life was not associated with increased PRBC transfusion.

Long-term continuous renal replacement therapy and anticoagulation with citrate in critically ill patients with severe liver dysfunction

Background

As of 2009, anticoagulation with citrate was standard practice in continuous renal replacement therapy (CRRT) for critically ill patients at the University Medical Centre of Saarland, Germany. Partial hepatic metabolism of citrate means accumulation may occur during CRRT in critically ill patients with impaired liver function. The aim of this study was to evaluate the actual influence of hepatic function on citrate-associated complications during long-term CRRT.

Methods

In a retrospective study conducted between January 2009 and November 2012, all cases of dialysis therapy performed in the interdisciplinary surgical intensive care unit were analysed. Inclusion criteria were CRRT and regional anticoagulation with citrate, pronounced liver dysfunction, and pathologically reduced indocyanine green plasma disappearance rate (ICG-PDR).

Results

A total of 1339 CRRTs were performed in 69 critically ill patients with liver failure. At admission, the mean Model for End-stage Liver Disease score was 19.2, and the mean ICG-PDR was 9.8%. Eight patients were treated with liver replacement therapy, and 30 underwent transplants. The mortality rate was 40%. The mean duration of dialysis was 19.4 days, and the circuit patency was 62.2 h. Accumulation of citrate was detected indirectly by total serum calcium/ionised serum calcium (tCa/iCa) ratio > 2.4. This was noted in 16 patients (23.2%). Dialysis had not to be discontinued for metabolic disorder or accumulation of citrate in any case. In 26% of cases, metabolic alkalosis occurred with pH > 7.5. Interestingly, no correlation between citrate accumulation and liver function parameters was detected. Moreover, most standard laboratory liver function parameters showed poor predictive capabilities for accumulation of citrate.

Conclusions

Our findings indicate that extra-hepatic metabolism of citrate seems to exist, avoiding in most cases citrate accumulation in critically ill patients despite impaired liver function. Because the citric acid cycle is oxygen-dependent, disturbed microcirculation would result in inadequate citrate metabolism. Raising the tCa/iCa ratio would therefore be an indicator of severity of illness and mortality rather than of liver failure. However, further studies are warranted for confirmation.

Early Spontaneous Abdominal Bleeding is associated with Poor Outcome in Moderate to Severe Acute Pancreatitis Patients: A Propensity Matched Study

Abdominal bleeding is a lethal complication in acute pancreatitis (AP) and it is commonly described as a late event. However, spontaneous intra-abdominal bleeding could occur very early but no study focusing on this phenomenon was published yet. In this study, 1137 AP patients were retrospectively screened and 24 subjects suffering early spontaneous bleeding (ESB) were selected. Meanwhile, a 1:1 well-balanced cohort of non-bleeding patients was generated by propensity score match. The clinical characteristics of these patients were compared and a multiple regression analysis was performed to assess the risk factors for ESB. Besides, patients with massive post-intervention bleeding (PIB) were collected for additional comparison. ESB patients suffered significantly worse outcome than the matched cohort evidenced by dramatically higher mortality than the non-bleeding patients and even the PIB group (54.2% versus 20.8%, P = 0.017; 54.2% versus 31.0%, P = 0.049). The regression analysis demonstrated computer tomography severity index (CTSI; OR, 3.34; 95% CI, 1.995–5.59, P < 0.001) and creatinine (OR, 1.008; 95% CI, 1.004–1.012, P < 0.001) were associated with the occurrence of ESB. In conclusion, ESB is a rare but dangerous complication of moderate-to-severe AP and may result in high mortality. CTSI and creatinine are independent risk factors for the development of ESB.

Effects of dialysis modality on blood loss, bleeding complications and transfusion requirements in critically ill patients with dialysis-dependent acute renal failure

Blood loss and bleeding complications may often be observed in critically ill patients on renal replacement therapies (RRT). Here we investigate procedural (i.e. RRT-related) and non-procedural blood loss as well as transfusion requirements in regard to the chosen mode of dialysis (i.e. intermittent haemodialysis [IHD] versus continuous veno-venous haemofiltration [CVVH]). Two hundred and fifty-two patients (122 CVVH, 159 male; aged 61.5±13.9 years) with dialysis-dependent acute renal failure were analysed in a sub-analysis of the prospective randomised controlled clinical trial-CONVINT-comparing IHD and CVVH. Bleeding complications including severity of bleeding and RRT-related blood loss were assessed. We observed that 3.6% of patients died related to severe bleeding episodes (between group P=0.94). Major all-cause bleeding complications were observed in 23% IHD versus 26% of CVVH group patients (P=0.95). Under CVVH, the rate of RRT-related blood loss events (57.4% versus 30.4%, P=0.01) and mean total blood volume lost was increased (222.3±291.9 versus 112.5±222.7 ml per patient, P <0.001). Overall, transfusion rates did not differ between the study groups. In patients with sepsis, transfusion rates of all blood products were significantly higher when compared to cardiogenic shock (all P <0.01) or other conditions. In conclusion, procedural and non-procedural blood loss may often be observed in critically ill patients on RRT. In CVVH-treated patients, procedural blood loss was increased but overall transfusion rates remained unchanged. Our data show that IHD and CVVH may be regarded as equivalent approaches in critically ill patients with dialysis-dependent acute renal failure in this regard.

Renal Replacement Therapy in the Pediatric Critical Care Unit

Renal replacement therapy is becoming more prevalent in the pediatric intensive care units for a large variety of disease states, including multiorgan dysfunction syndrome, fluid overload, and electrolyte imbalance. Three modalities-continuous renal replacement therapy, hemodialysis, and peritoneal dialysis-are commonly used. When deciding among the three therapies, there are several advantages and disadvantages of each modality that must be considered. This manuscript provides an overview of each modality as well as its pros and cons.

Circuit life versus bleeding risk: the impact of achieved activated partial thromboplastin time versus achieved filtration fraction

Whilst prolonging hemofilter (circuit) life, heparin increases bleeding risk. The impact of achieved activated partial thromboplastin time (APTT) on circuit life and bleeding risk has not been assessed in a modern critically ill cohort. Lowering filtration fraction may be an alternative means of prolonging circuit life, but is often overlooked in critical care. An observational study of 309 consecutive circuits in a general intensive care unit was conducted using a wide target APTT range. Multilevel modeling was used to predict circuit life and bleeding according to achieved APTT and filtration fraction. Independent predictors of circuit failure (i.e. unplanned ending of treatment) included filtration fraction (P<0.001, HR 1.07 per 1% increase), peak APTT (P<0.001, HR 0.8 per 10 s increase or 0.3 APTR increase) and baseline PT (P=0.014, HR 0.91 for every 50% increase). The only significant predictor of bleeding was peak APTT (P=0.017, OR 1.05 per 10 s increase). Every 10 s APTT increase was associated with a 20% reduction in circuit failure, but a 5% increase in hemorrhage. A 3% reduction in filtration fraction was associated with the same improvement in circuit life as a 10 s increase in APTT. Increasing APTT prolongs circuit life but carries a substantial risk of bleeding even in modern practice. Filtration fraction has a large impact on circuit life in the critically ill: a 3% reduction in filtration fraction, e.g. by increasing blood flow or delivering some of the clearance via dialysis, would be expected to reduce circuit failure as much as a 10 s increase in APTT.

Changes in plasma kynurenic acid concentration in septic shock patients undergoing continuous veno-venous haemofiltration

Kynurenic acid (KYNA) is one of the end products of tryptophan metabolism. The aim of this study was to analyse plasma KYNA concentration in septic shock patients (SSP) with acute kidney injury (AKI) undergoing continuous veno-venous haemofiltration (CVVH). Changes in KYNA content were compared to alterations in the levels of procalcitonin (PCT), C-reactive protein and lactate. Adult SSP with AKI were examined. Measurements were conducted at seven time points: before beginning CVVH and at 6, 12, 24, 48, 72 and 96 h after the beginning of CVVH. Based on clinical outcomes, the data were analysed separately for survivors and non-survivors. Twenty-seven patients were studied. CVVH was associated with reduced plasma KYNA concentration only in survivors. Plasma KYNA concentration correlated with the levels of lactate and PCT only in survivors. (1) CVVH reduced plasma KYNA concentration only in survivors; (2) lack of this reduction may predict fatal outcomes in SSP.

Platelet Consumption and Filter Clotting Using Two Different Membrane Sizes during Continuous Venovenous Haemodiafiltration in the Intensive Care Unit

Background. The aim of this study was to investigate whether different haemofilter surface areas affect clotting and platelet consumption in critically ill patients undergoing continuous venovenous haemodiafiltration (CVVHDF). Methods. CVVHDF was performed in postdilution technique using a capillary haemofilter with two different membrane sizes, Ultraflux AV 1000S (n = 17, surface 1.8 m², volume 130 mL), and the smaller AV 600S (n = 16, surface 1.4 m², volume 100 mL), respectively. Anticoagulation was performed with heparin. Results. No significant differences were found when the two filters were compared. CVVHDF was performed for 33 (7–128) hours with the filter AV 1000S and 39 (7–97) hours with AV 600S (P = 0.68). Two (1–4) filters were utilised in both groups over this observation period (P = 0.94). Platelets dropped by 52,000 (0–212,000) in AV 1000S group and by 89,500 (0–258,000) in AV 600S group (P = 0.64). Haemoglobin decreased by 1.2 (0–2.8) g/dL in AV 1000S group and by 1.65 (0–3.9) g/dL in AV 600S group (P = 0.51), leading to the transfusion of 1 (0–4) unit of blood in 19 patients (10 patients with AV 1000S and 9 with AV 600S). Filter observation was abandoned due to death (12.1%), need for systemic anticoagulation (12.1%), repeated clotting (36.4%), and recovery of renal function (39.4%). Conclusion. Our study showed that a larger filter surface area did neither reduce the severity of thrombocytopenia and anaemia, nor decrease the frequency of clotting events.

Use of argatroban: experiences in continuous renal replacement therapy in critically ill patients after cardiac surgery

OBJECTIVES

Acute kidney injury requiring renal replacement therapy (RRT) is a common complication after cardiac surgery, complicated by suspected or proven heparin-induced thrombocytopenia (type II). The present study evaluated the use of argatroban as an anticoagulant during continuous RRT in the early period after cardiac surgery. Argatroban was compared with unfractionated heparin (UH) with respect to bleeding complications and the effectiveness of anticoagulation.

METHODS

Patients requiring RRT after cardiac surgery from March 2007 to June 2009 were identified. The effectiveness of anticoagulation was measured indirectly by the duration of dialysis filter use. Bleeding was defined as clinical signs of blood loss or the need for transfusion.

RESULTS

Of 94 patients, 41 received argatroban, 27 UH, and 26 required conversion from UH to argatroban. In all 3 subgroups, RRT was begun within a median postoperative period of 2.0 days. Similar levels of anticoagulation were achieved with the duration of the circuit and filter changed an average of 1.1 times daily during RRT. Liver function was comparable in all patients. Neither clinically relevant signs of bleeding nor significant differences in the hemoglobin levels or a requirement for transfusion were noted. However, the Simplified Acute Physiology Score II values during dialysis and mortality were significantly greater in the patients initially receiving argatroban compared with those who received UH alone (54 ± 2 vs 43 ± 3, P < .001; 71% vs 44%, P = .04).

CONCLUSIONS

Argatroban can provide effective anticoagulation in postoperative cardiac patients receiving continuous RRT. Close monitoring and dose titration resulted in a comparable risk of bleeding for anticoagulation with both argatroban and heparin, regardless of the disease severity or impaired hepatic function.

Beyond the randomized clinical trial: citrate for continuous renal replacement therapy in clinical practice

BACKGROUND

Premature circuit clotting is a major problem during continuous renal replacement therapy (CRRT). Six randomized controlled trials confirmed that regional anticoagulation with citrate is superior to heparin. Our objective was to compare circuit patency with citrate, heparin and epoprostenol in routine clinical practice.

METHODS

We retrospectively analysed data on circuit patency of all circuits used in a single centre between September 2008 and August 2009. We differentiated between premature filter clotting, elective discontinuation and waste.

RESULTS

309 patients were treated with CRRT (n = 2,059 circuits). The mean age was 65.7; 63.8% were male. The methods to maintain circuit patency were unfractionated heparin (42.3%), epoprostenol (23.0%), citrate (14.7%), combinations of different anticoagulants (14.6%) and no anticoagulation (4.7%). Premature clotting was the most common reason for circuit discontinuation among circuits anticoagulated with heparin, epoprostenol or combinations of different anticoagulants (59-62%). Among circuits anticoagulated with citrate the main reason for discontinuation was elective (61%). Hazard regression analysis confirmed significantly better circuit survival with citrate. Changing from heparin to citrate decreased the risk of premature circuit clotting by 75.8%.

CONCLUSION

In routine clinical practice, regional anticoagulation with citrate is associated with significantly better circuit patency than heparin or epoprostenol.

Discrepant results from laboratories impact patients receiving heparin or antithrombin therapy

Despite improvements achieved in laboratory medicine over the years, discrepant results from different clinical laboratories are still a source of imminent risk to patients and the pharmaceutical industry. The problem is aggravated by a disconnect between the in vitro diagnostic community and clinicians or drug developers. This is the sequel to a previous report where data from proficiency testing, originally established as a tool for good laboratory practice, were used to highlight the size of the problem, and its possible impact on patients and pharmaceutical trials. Results from three laboratory tests commonly used as tools to monitor patients undergoing therapy with heparin or antithrombin agents, activated partial thromboplastin time, anti-factor Xa and thrombin time, were investigated. Unfortunately, data show that, owing to an absence of standardization approaches or a reasonable technique to harmonize results from different laboratories, results for the same sample, if analyzed by different laboratories or even by one laboratory employing different platforms or reagents, can be extremely different and misleading.