Point-of-Care Testing for Anticoagulation Monitoring in Neuroendovascular Procedures

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Fig 1.
Simplified diagram depicting the coagulation cascade and targets of action of different anticoagulants. The coagulation cascade consists of the intrinsic, extrinsic, and common pathways. Note the positive feedback effect of thrombin on further activation of the intrinsic and common pathways. All anticoagulants target factors of the intrinsic and common pathway except warfarin, which decreases the rate of hepatic synthesis of factor VII.

Table 1:

Overview of some important facts on anticoagulation and ACT

ACT and Anticoagulation Facts

Celite, kaolin, and glass are activators used to measure ACT that yield different results
Celite-ACT is significantly longer than kaolin ACT
ACT values from a particular device are reproducible and correlate with anti-Xa values
ACT is device-specific even if the activator used is the same
ACT following administration of heparin varies based on heparin-dependent (heparin responsiveness/resistance) and heparin-independent (hemodilution, hypothermia, platelet count, race, and so forth) factors
LMWH anticoagulation can be monitored by ACT
Hemonox-CT is a more specific POC test for LMWH
Concomitant use of abciximab increases ACT; eptifibatide leads to less marked changes in ACT
Concomitant aprotinin administration affects Celite-ACT more than kaolin-ACT
Heparin concentrations are divided into high (>1 U/mL) and low (<1 U/mL)
Kaolin-based ACT is less accurate in low-intensity anticoagulation
Glass beads in a plastic tube are more effective in moderate heparin concentrations
Hemochron produces lower ACT values than the Automated Coagulation Timer System (previously HemoTec)
The corresponding anti-Xa values are needed to establish a therapeutic ACT range for a particular device
Institutions should establish their individual therapeutic ACT ranges

Table 2:

Overview of main POC devices used to measure ACT

Manufacturer	Device	ACT Test	Reagent	Detection Method	Remarks
International Technidyne	Hemochron Jr. Signature, Signature+, and Signature Elite	ACT and ACT-LR	Kaolin	Optical	Result is automatically converted to a reference Celite-ACT value
	Hemochron Response	3 different ACT tests: FTCA510, KACT, P214	Celite in glass tube (high heparin levels), kaolin in glass tube (if aprotinin is present), glass beads in plastic tube (low heparin levels)	Mechanical	Other capabilities: RxDx heparin/protamine dosing system
	Hemochron Jr. Hemonox	Hemonox-CT	Proprietary lipidated recombinant–rabbit-brain tissue factor	Mechanical	Designed specifically to monitor LMWH
Medtronic	HMS PLUS	ACT-HR	Celite	Mechanical	Other capabilities: heparin dose response and heparin protamine titration
	ACT PLUS	ACT-LR	Celite	Mechanical
Sienco	Sonoclot	Aprotinin-insensitive ACT (SaiACT)	Celite + clay	Mechanical
Abbott Laboratories	i-STAT	Celite-ACT, kaolin-ACT	Celite kaolin	Electrochemical
Instrumentation Laboratory	GEM PCL	ACT, ACT-LR	Kaolin (for ACT), Celite + silica (for ACT-LR)	Optical
Helena Laboratories	Cascade	Celite-ACT	Celite	Photomechanical	Can also perform Enox and LMWH tests
	Actalyke XL, Actalyke Mini II	Celite-ACT, kaolin-ACT, glass-ACT, MAX-ACT	Celite, kaolin, glass, or a cocktail of Celite, kaolin and glass	2-Point, electromechanical	Linear correlation with heparin level ≤10 U/mL for XL model and 6 U/mL for Mini II model tubes can be used in Hemochron system