Anticoagulation Monitoring Part 1: Warfarin and Parenteral Direct Thrombin Inhibitors

The 2023 WSES guidelines on the management of trauma in elderly and frail patients

BACKGROUND

The trauma mortality rate is higher in the elderly compared with younger patients. Ageing is associated with physiological changes in multiple systems and correlated with frailty. Frailty is a risk factor for mortality in elderly trauma patients. We aim to provide evidence-based guidelines for the management of geriatric trauma patients to improve it and reduce futile procedures.

METHODS

Six working groups of expert acute care and trauma surgeons reviewed extensively the literature according to the topic and the PICO question assigned. Statements and recommendations were assessed according to the GRADE methodology and approved by a consensus of experts in the field at the 10th international congress of the WSES in 2023.

RESULTS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage, including drug history, frailty assessment, nutritional status, and early activation of trauma protocol to improve outcomes. Acute trauma pain in the elderly has to be managed in a multimodal analgesic approach, to avoid side effects of opioid use. Antibiotic prophylaxis is recommended in penetrating (abdominal, thoracic) trauma, in severely burned and in open fractures elderly patients to decrease septic complications. Antibiotics are not recommended in blunt trauma in the absence of signs of sepsis and septic shock. Venous thromboembolism prophylaxis with LMWH or UFH should be administrated as soon as possible in high and moderate-risk elderly trauma patients according to the renal function, weight of the patient and bleeding risk. A palliative care team should be involved as soon as possible to discuss the end of life in a multidisciplinary approach considering the patient's directives, family feelings and representatives' desires, and all decisions should be shared.

CONCLUSIONS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage based on assessing frailty and early activation of trauma protocol to improve outcomes. Geriatric Intensive Care Units are needed to care for elderly and frail trauma patients in a multidisciplinary approach to decrease mortality and improve outcomes.

Benefits and Pitfalls of Point-of-Care Coagulation Testing for Anticoagulation Management: An ACLPS Critical Review

Objectives

Point-of-care (POC) testing is generally less precise and has higher reagent costs per test than laboratory-based assays. However, POC hemostasis testing can offer significant advantages in particular situations: patient-managed warfarin therapy as well as rapid turnaround time heparin management for intraoperative patients. Of note, POC hemostasis testing is generally approved for the purposes of anticoagulation monitoring and is inferior to laboratory coagulation testing for the diagnosis of congenital or acquired coagulopathy.

Methods

The frequently used POC coagulation instruments for POC international normalized ratio and activated clotting time are reviewed, as well as their typical performance relative to central laboratory testing (where available).

Results

Several cases are discussed that highlight the benefits, as well as pitfalls, of POC coagulation testing.

Conclusions

POC coagulation testing for anticoagulation monitoring offers advantages in particular situations. Clear policies and protocols must be developed to guide proper use of POC versus central laboratory hemostasis testing.

Erratum to: Pharmacology of anticoagulants used in the treatment of venous thromboembolism

Anticoagulant drugs are the foundation of therapy for patients with VTE. While effective therapeutic agents, anticoagulants can also result in hemorrhage and other side effects. Thus, anticoagulant therapy selection should be guided by the risks, benefits and pharmacologic characteristics of each agent for each patient. Safe use of anticoagulants requires not only an in-depth knowledge of their pharmacologic properties but also a comprehensive approach to patient management and education. This paper will summarize the key pharmacologic properties of the anticoagulant agents used in the treatment of patients with VTE.

Pharmacology of anticoagulants used in the treatment of venous thromboembolism

Anticoagulant drugs are the foundation of therapy for patients with VTE. While effective therapeutic agents, anticoagulants can also result in hemorrhage and other side effects. Thus, anticoagulant therapy selection should be guided by the risks, benefits and pharmacologic characteristics of each agent for each patient. Safe use of anticoagulants requires not only an in-depth knowledge of their pharmacologic properties but also a comprehensive approach to patient management and education. This paper will summarize the key pharmacologic properties of the anticoagulant agents used in the treatment of patients with VTE.

Precision and accuracy of point-of-care testing coagulometers used for self-testing and self-management of oral anticoagulation therapy

BACKGROUND

Oral anticoagulation therapy is monitored by the use of the International Normalized Ratio (INR). Patients who perform self-testing or self-management use a point-of-care testing (POCT) coagulometer (INR monitor) to estimate their INRs. A precondition for a correct dosage of coumarins is a correct INR estimation, and the method and apparatus used for providing the INR measurements are crucial in this context. Several studies have been published regarding the precision and accuracy of these POCT coagulometers, and have led to diverse conclusions. It is difficult and challenging to perform an overview of the literature, owing to the vast amount of papers, with differences in design, statistical analysis, etc.

OBJECTIVES

The aim of this systematic review was to analyze the current literature, especially regarding the precision and accuracy of the POCT coagulometers, to provide recommendations for clinical use and quality control, and to point out areas for future research.

METHODS

We included a total of 22 studies, of which four were characterized as high-quality studies.

RESULTS

The precision of the POCT coagulometers was generally adequate for clinical use. Their performance in terms of accuracy has to be viewed in the context of the inherent inaccuracies of INR measurements.

CONCLUSIONS

The accuracy of POCT coagulometers seems, in this respect, to be generally acceptable, and they can be used in a clinical setting.

Acute toxicity, histopathology, and coagulopathy in American kestrels (Falco sparverius) following administration of the rodenticide diphacinone

The acute oral toxicity of the anticoagulant rodenticide diphacinone was found to be over 20 times greater in American kestrels (Falco sparverius; median lethal dose 96.8 mg/kg body weight) compared with Northern bobwhite (Colinus virginianus) and mallards (Anas platyrhynchos). Modest evidence of internal bleeding was observed at necropsy, although histological examination of heart, liver, kidney, lung, intestine, and skeletal muscle revealed hemorrhage over a wide range of doses (35.1-675 mg/kg). Residue analysis suggests that the half-life of diphacinone in the liver of kestrels that survived was relatively short, with the majority of the dose cleared within 7 d of exposure. Several precise and sensitive clotting assays (prothrombin time, Russell's viper venom time, thrombin clotting time) were adapted for use in this species, and oral administration of diphacinone at 50 mg/kg increased prothrombin time and Russell's viper venom time at 48 and 96 h postdose compared with controls. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and generally corresponded with the onset of overt signs of toxicity and lethality. In view of the toxicity and risk evaluation data derived from American kestrels, the involvement of diphacinone in some raptor mortality events, and the paucity of threshold effects data following short-term dietary exposure for birds of prey, additional feeding trials with captive raptors are warranted to characterize more fully the risk of secondary poisoning.

[Portable coagulometer devices in the monitoring and control of oral anticoagulation therapy: a systematic review]

OBJECTIVE

To compare portable coagulometer devices and conventional coagulometers. The clinical validity will be estimated via anticoagulation control (maintenance of therapeutic range), patient satisfaction, thrombotic or haemorrhagic events and mortality. Analytical validity will be studied in quality control terms.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE and EMBASE databases, CRD, Cochrane, EMEA, FDA, EuroScan and the ClinicalTrials.gov.

METHODS

Inclusion criteria were studied in patients on anticoagulation therapy who used portable coagulometer devices. In an additional undertaking, the comparison with lab references was looked for, in order to evaluate the effectiveness. The quality of selected studies was assessed according to CASPe check-list. As meta-analysis was not possible, a qualitative synthesis was made.

RESULTS

Four evaluation reports and 7 systematic reviews were selected (two of them with meta-analysis). After these, 22 original articles were included for this review and they had high or very high score for CASPe check-list (≥7/10). Almost all of the studies found very high correlations between portable coagulometer devices and conventional coagulometers (r>90), and clinical advantages such as lower incidence of thromboembolism events. Three systematic reviews showed a lower mortality index.

CONCLUSIONS

The analytical-validity related articles show that portable coagulometers have an equivalent effectiveness to conventional coagulometers. Studies that include patient-reported outcomes show that self-monitoring patients, by means of portable coagulometers, have better analytical measurement results and fewer rates of thromboembolic events. Survival was analysed in very few studies; nevertheless, all of these show lower mortality. Similarly, the minority of selected articles includes economic evaluations, although they suggest a better cost-effectiveness of portable coagulometers compared to the conventional mode.

Acute toxicity of diphacinone in Northern bobwhite: effects on survival and blood clotting

The anticoagulant rodenticide diphacinone was slightly toxic (acute oral LD50 2014 mg/kg) to Northern bobwhite (Colinus virginianus) in a 14-day acute toxicity trial. Precise and sensitive assays of blood clotting (prothrombin time, Russell's Viper venom time, and thrombin clotting time) were adapted for use in quail, and this combination of assays is recommended to measure the effects of anticoagulant rodenticides. A single oral sublethal dose of diphacinone (434 mg/kg body weight) prolonged clotting time at 48 h post-dose compared to controls. At 783 mg/kg (approximate LD02), clotting time was prolonged at both 24 and 48 h post-dose. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and was detected before overt signs of toxicity were apparent at the greatest dosages (2868 and 3666 mg/kg) in the acute toxicity trial. These clotting time assays and toxicity data will assist in the development of a pharmacodynamic model to predict toxicity, and also facilitate rodenticide hazard and risk assessments in avian species.

Anticoagulation: Low-Molecular-Weight Heparins in Renal Impairment and Obesity: Available Evidence and Clinical Practice Recommendations Across Medical and Surgical Settings

Objective

To develop practical recommendations for the use of low-molecular-weight heparins (LMWHs) as prophylaxis and treatment of venous thromboembolism and acute coronary syndromes in patients with impaired renal function or obesity.

Data Sources

Multiple MEDLINE searches were performed (November 2008) to identify studies for inclusion, using a comprehensive list of search terms including, but not limited to, LMWH, enoxaparin, dalteparin, tinzaparin, obesity, weight, renal, kidney, elderly, monitoring, and anti-Xa.

Study Selection And Data Extraction

Only articles published in English that were relevant for this review were included.

Data Synthesis

In the majority of patients, standardized prophylaxis or treatment doses of LMWHs can be used without the need for monitoring and adjusting regimens. For patients with severe renal impairment (estimated creatinine clearance [CrCl] <30 mL/min), doses of some LMWHs should be adjusted or unfractionated heparin should be used instead. CrCl should be estimated using the Cockcroft-Gault method. Differences are noted in the degree of accumulation of various LMWHs in patients with moderate-to-severe renal impairment, and thus, the degree of dose adjustment may differ among the various LMWHs. Increasing the prophylactic doses of LMWH may be appropriate in morbidly obese patients (body mass index ≥40 kg/m2). The use of total body weight is appropriate for therapeutic doses of LMWH in obese patients. Laboratory monitoring of the anticoagulation effect of LMWHs is generally not necessary, but should be considered in patients with morbid obesity (weight >190 kg), those with severe renal impairment, and those with moderate renal impairment with prolonged (>10 days) LMWH use. When anti-Xa activity is monitored, it should be determined using a chromogenic method and a calibration curve based on the LMWH used.

Conclusions

Additional data are needed for specific dose guiding in obese and renally impaired patients, who are often excluded from larger clinical trials. Practice recommendations are made based on available evidence and authors' clinical opinions.

Anticoagulation Monitoring Part 2: Unfractionated Heparin and Low-Molecular-Weight Heparin

OBJECTIVE

To review the availability, mechanisms, limitations, and clinical application of point-of-care (POC) devices used in monitoring anticoagulation with unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs).

DATA SOURCES

Articles were identified through a MEDLINE search (1966–August 2004), device manufacturer Web sites, additional references listed in articles and Web sites, and abstracts from scientific meetings.

STUDY SELECTION AND DATA EXTRACTION

English-language literature from clinical trials was reviewed to evaluate the accuracy, reliability, and clinical application of POC monitoring devices.

DATA SYNTHESIS

The activated partial thromboplastin time (aPTT) and activated clotting time (ACT) are common tests for monitoring anticoagulation with UFH. Multiple devices are available for POC aPTT, ACT, and heparin concentration testing. The aPTT therapeutic range for UFH will vary depending upon the reagent and instrument employed. Although recommended by the American College of Chest Physicians Seventh Conference on Antithrombotic and Thrombolytic Therapy, establishing a heparin concentration–derived therapeutic range for UFH is rarely performed. Additional research evaluating anti-factor Xa monitoring of LMWHs using POC testing is necessary.

CONCLUSIONS

Multiple POC devices are available to monitor anticoagulation with UFH. For each test, there is some variability in results between devices and between reagents used in the same device. Despite these limitations, POC anticoagulation monitoring of UFH using aPTT and, more often, ACT is common in clinical practice, particularly when evaluating anticoagulation associated with interventional cardiology procedures and cardiopulmonary bypass surgery.