Journal: J Clin Anesth 19(3):230-233, 2007. 19 References
Reprint: Dept of Anesthesia, Stanford University School of Medicine, Stanford, CA 94305 (B Carvalho, MD)
Faculty Disclosure: Abstracted by R. Klotz, who has nothing to disclose.
von Willebrand disease (vWD) is the most common hereditary clotting disorder, with a prevalence of 1% to 2%. Type 1 vWD is associated with quantitative deficiencies of von Willebrand factor (vWF) and factor VIII, which results in mild to moderate bleeding episodes. Both vWF and factor VIII increase in pregnancy, peaking in the third trimester. A 36-yr-old parturient with a twin pregnancy with type 1 vWD and asymptomatic scoliosis was admitted in preterm labor at 31 weeks gestation. IV magnesium was started for tocolysis, which was later changed to oral nifedipine. Prothrombin time was 10.9 seconds (reference range [rr], 9.8-12.8 sec) and activated partial thromboplastin time was 27.8 seconds (rr, 24-38 sec). Factor VIII assay was 279% (rr, 57%-196%), a vWF of more than 200% (rr, > 60%), and a ristocetin coefficient of more than 273% (rr, > 40%) were noted. The recommendations in the literature suggested that maintaining factor VIII levels to more than 30% would minimize the risk of bleeding postdelivery.
At 34 weeks gestation, the patient had spontaneous rupture of membranes, and the decision for cesarean section was expedited. Before surgery, factor VIII assay was 189%, the vWF was > 200%, and the ristocetin coefficient was 247%. The patient’s preoperative hematocrit was 36.7% (rr, 35%-47%). Metoclopramide 10 mg IV and ranitidine 50 mg IV were given, and an infusion of desmopressin acetate (DDAVP) 0.3 mcg/kg was given over 20 minutes. Spinal anesthesia was attempted, but due to scoliosis attempts at L3-L4 were unsuccessful. The patient wanted to avoid general anesthesia, therefore a combined spinal-epidural anesthetic was attempted. The epidural space was identified with a 17-ga Tuohy needle at L2-L3 using the loss of resistance technique. A 26-ga spinal needle was inserted through the Tuohy needle into the subarachnoid space. A 1.6 mL dose of hyperbaric 0.75% bupivacaine with 10 mcg fentanyl and 200 mcg preservative-free morphine was injected subarachnoid, and a 19-ga epidural catheter was inserted. A sensory level of T2 was noted. The cesarean section proceeded without difficulty and at the end of surgery the epidural catheter was removed without neurologic complication or postpartum hemorrhage. The postpartum course was uneventful, and before discharge the patient’s hematocrit was 26.2% and her factor VIII assay was 202%. She was discharged on postoperative day 3.
von Willebrand disease is caused by a deficiency or a functional defect of vWF, which is a key component in the hemostatic process that occurs in response to vascular injury. More than 20 different types of vWD exist, and three phenotypes account for most clinical presentations. Type 1 vWD is the most common variant, accounting for 60%-80% of cases. It is characterized by a 5%-30% reduction in vWF and factor VIII but retains a structurally normal multimeric configuration. Type 2 vWD encompasses qualitative defects in vWF and is subdivided into 4 main subtypes: 2A, 2B, 2M and 2N. Type 2B vWD can be particularly problematic because this subtype is normally accompanied by thrombocytopenia, which can be exacerbated in pregnancy. Type 3 vWD is the most severe form of the disease and is characterized by negligible or absent levels of vWF, as well as significantly reduced levels of factor VIII coagulant.
The risk of bleeding in women with type 1 vWD may recede in the antepartum period because of progressive increases in factor VIII and vWF during pregnancy. However, uncertainty exists regarding the extent of these changes in pregnancy. There are no clear guidelines on laboratory monitoring or indications for regional or general anesthesia for patients with type 1 vWD. In the patient presented, the authors state that they would have performed general anesthesia on the patient if her factor VIII or vWF levels were below reference ranges.
Desmopressin acetate is a synthetic analogue of vasopressin that increases plasma vWF and factor VIII levels. Thirty to sixty minutes after DDAVP administration, vWF levels increase 3-5 times higher than baseline. Patients with type 1 vWD are likely to show a good response to DDAVP. Therefore, DDAVP has been commonly used as prophylaxis against postpartum bleeding in patients with type 1 vWD before delivery. However, there are adverse effects associated with DDAVP, including mild tachycardia, headache, and flushing. Fluid retention can also occur because of an antidiuretic effect.
In the other vWD subtypes there are variable responses to DDAVP. In patients with inadequate responses to DDAVP, such as those with types 2 and 3 vWD, intermediate and high-purity infusions of vWF and factor VIII Humate-P and Alphanate are commonly used.
If an epidural catheter is placed, the authors recommend the removal of the catheter as soon as possible after delivery. The risk of spinal hematoma anesthesia in obstetric patients is rare after epidural (1:200,000). In the postpartum period, maternal factor VIII activity decreases and the risk of bleeding is increased. However, the risk of postpartum hemorrhage is minimal if plasma factor VIII levels are at least 30% to 40% of normal levels. Therefore, close monitoring of factor VIII and vWF is advised in patients with type 1 vWD because of the variability in these levels during pregnancy.
Any decision to use a regional anesthetic technique should be individualized. Further formal evaluation of neuraxial anesthesia in this patient population is necessary to establish consensus for routine practice of this technique. |
