Heparin reduces neurological impairment after cerebral arterial air embolism in the rabbit.
OBJECTIVE
Neurological injury after cerebral air embolism may be due to thromboinflammatory responses at sites of air-injured endothelium. Because heparin inhibits multiple thromboinflammatory processes, we hypothesized that heparin would decrease neurological impairment after cerebral air embolism.


METHODS
To first establish a dose of air that would cause unequivocal neurological injury, anesthetized New Zealand White rabbits received either 0, 50, 100, or 150 microL/kg of air into the internal carotid artery (n = 5 in each group). One hour later, anesthesia was discontinued. Animals were neurologically evaluated at 24 hours with the use of a scale ranging from 0 (normal) to 97 (coma) points. In a subsequent experiment, anesthetized rabbits received either heparin (n = 17) or saline (n = 15) 5 minutes before air injection (150 microL/kg). Heparin was given as a 200-IU/kg bolus and followed by a constant infusion of 75 IU.kg-1.h-1 for 2 hours. Equal volumes of saline were given to control rabbits. Two hours later, anesthesia was discontinued. Animals were neurologically evaluated 24 hours after air embolism.


RESULTS
There was a monotonic relationship between dose of air and severity of neurological impairment at 24 hours (P = 1.1 x 10(-7)). Animals receiving 150 microL/kg of air were unequivocally injured (score, 60 +/- 16). In the second experiment, heparin animals had significantly less neurological impairment at 24 hours (34 +/- 14) than saline controls (52 +/- 8) (P = .0013).


CONCLUSIONS
When given prophylactically, heparin decreases neurological impairment caused by severe cerebral arterial air embolism.
Ryu
K H
KH
Department of Anesthesiology, Catholic University Medical College, Kangnam Saint Mary's Hospital, Seoul, Korea.
Hindman
B J
BJ
Reasoner
D K
DK
Dexter
F
F
D000818:Animals; D000925:Anticoagulants / Q000627:therapeutic use*; D001522:Behavior, Animal / Q000187:drug effects*; D001794:Blood Pressure; D003243:Consciousness / Q000187:drug effects*; D003391:Cranial Nerves / Q000187:drug effects / Q000503:physiopathology*; D004618:Embolism, Air / Q000188:drug therapy / Q000503:physiopathology*; D005684:Gait / Q000187:drug effects; D006493:Heparin / Q000627:therapeutic use*; D002542:Intracranial Embolism and Thrombosis / Q000188:drug therapy / Q000503:physiopathology*; D009043:Motor Activity / Q000187:drug effects*; D011817:Rabbits; D012119:Respiration / Q000187:drug effects; D013997:Time Factors
D000925:Anticoagulants; D006493:Heparin