we identified five common practices that led to delays in achieving a ptt greater than 1.5 times the laboratory control : ( 1 ) failure to start heparin therapy at the time of initial clinical suspicion , ( 2 ) choice of a heparin sodium bolus ( mean , 5861 +/- 365 u ) and continuous infusion ( 1026 +/- 148 u/h ) insufficient to elevate the ptt to greater than 1.5 times control , ( 3 ) delay in obtaining the first ptt ( mean , 11.7 +/- 1 h after start of heparin therapy ) , ( 4 ) insufficient heparin dosing in response to a low ptt , and ( 5 ) excessive and prolonged reductions in heparin therapy in response to a ptt greater than three times control , leading to subtherapeutic levels in 56 % of subsequent ptts .
C0037513
heparin sodium
C0019134
heparin