Abstract: . . .  intervals and aPTT is monitored at the mid-dosing interval (i.e., 6 hours after a dose). For L.N., whose current heparin dosage is 1,700 U/hour, the initial SC heparin dose would be 20,500 U (1,700 U/hour 12 hours and rounded to the nearest 500 U). Because a 20,000- U/mL preparation should be used to minimize the administra- tion volume, the dose should be simplified to 20,000 U SC every 12 hours. L.N.s aPTT should be checked 6 hours after the first dose, with adjustment of dosing as necessary. Because of the reduced bioavailability of SC heparin in comparison with IV administration, increased dosing may be required. A weight-based dosing nomogram, specific for a reagent with a THROMBOSIS 16- 11 Koda-Kimble_Ch16_001-034 4/6/04 8:42 AM Page 11 Page 12 therapeutic aPTT range of 60 to 100 seconds, is described in Table 16-7. REVERSAL OF EFFECT 14. P.B. is a 64-year-old woman with DVT. On day 4 of hep- arin therapy, she received 25,000 U of heparin during a 1-hour period as a result of an infusion pump malfunction. The infusion was stopped and within 30 minutes, she became diaphoretic and hypotensive. Bright red blood was evident upon rectal examina-  . . .
. . .  arin therapy, and appears to be reversible after discontinuation of heparin. 5 Patients with diabetes or renal failure may be at greatest risk. Hypersensitivity Reactions. Other rarely occurring adverse ef- fects associated with heparin include generalized hypersensi- tivity reactions, such as urticaria, rash, rhinitis, conjunctivitis, asthma, and angioedema, as well as a reversible temporal alopecia. 5 ADJUSTED-DOSE SUBCUTANEOUS ADMINISTRATION 13. By day 4 of heparinization, IV access for L.N. has become difficult. What alternatives can be considered? The most common strategy for treatment of venous throm- bosis in hospitalized patients without IV access is the use of SC LMWH (see Question 15). Another alternative is SC ad- ministration of unfractionated heparin with adjustment of dosing to maintain a therapeutic aPTT. 29 Typically, SC heparin is administered at 12-hour intervals and aPTT is monitored at the mid-dosing interval (i.e., 6 hours after a dose). For L.N., whose current heparin dosage is 1,700 U/hour, the initial SC heparin dose would be 20,500 U (1,700 U/hour 12 hours and rounded to the nearest 500 U). Because a 20,000- U/mL preparation should be used to minimize the administra- tion volume, the dose should be simplified to 20,000 U SC every 12 hours. L.N.s aPTT should be checked . . .
--3000,2,750,3012,64553