Hemorrhagic complications can occur after virtually all regional anesthetic techniques. Bleeding into the spinal canal is perhaps the most serious of these complications. A review of a large number of clinical reports shows that this can happen in clinical circumstances in which subarachnoid (SAB) or epidural block (EDB) is performed.
Spinal hematoma (SH) can even occur in a young, otherwise healthy patient, who is not on any anticoagulant, has a normal coagulation profile, and receives SAB or EDB after a clean, single puncture performed by an experienced anesthetist using a small gauge needle (Chapter 59).
Tryba estimates the risk of SH to be 1:150,000 after EDB, and 1:220,000 after SAB. However, for medico-legal reasons, the real incidence may be under-reported. SAB is probably less traumatic than EDB. Spinal bleeding occurs in a significant number of patients in whom central nerve block (CNB) has been performed using accepted guidelines. The potential development of an SH in patients receiving CNB must always be kept in mind whether or not an anticoagulant has been used (1). Following surgery, a hypercoagulable state usually occurs. The etiology of this is uncertain but the stress response appears to be an important initiator. EDB may prevent some of the complications which flow from this state and may improve clinical outcome (compared with inhalational anaesthesia alone). This has been confirmed experimentally and clinically in vascular surgery (2). The beneficial effects of regional anesthesia on coagulation in patients on anticoagulants have not been quantitated.
With regard to the effects of preoperative antiplatelet therapy on the risk of SH, Horlocker reported results obtained from an extensive study using 924 patients who underwent major orthopedic surgery (Chapter 34). Preoperative antiplatelet therapy did not increase the incidence of minor hemorrhagic complications. However:
1. female gender,
2. increased age,
3. a history of excessive bruising/bleeding,
4. surgery to the hip,
5. a continuous catheter technique,
6. a large needle gauge,
7. multiple needle passes, and
8. difficult needle placement
were all significant risk factors.
'Bloody tap' is relatively common (3 to 4%) but it usually produces a clinically insignificant collection of blood in the epidural space.
Preoperative antiplatelet therapy is not a significant risk factor for the development of neurological dysfunction from SH in patients who undergo SAB or EDB while receiving these medications (3).
Guidelines for safer CNB in a woman with impaired coagulation:
1. Perform CNB only if:
a. PT is less than 1.5 times the international normalized ratio,
b. APTT is less than 1.5 times control,
c. platelet is 80,000 or greater, and
d. bleeding time is < 10 min.
2. If a bloody tap occurs, postpone surgery for 24h if possible and place the patient under strict neurologic surveillance;
3. Remove the CNB catheter when the coagulation profile has returned to normal.
Guidelines for safer CNB in a woman who is heparinised, or in whom heparinisation is planned:
1. Heparin should be stopped 3-6hrs before CNB;
2. Withold CNB if clotting times remain abnormal;
3. If bleeding occurs during needle or catheter insertion in patients who are heparinized later, close neurological observation is mandatory following delivery or surgery;
4. Observe a minimum time interval of 60min between initiation of CNB and subsequent heparinization.
5. Remove the CNB catheter as early as possible prior to reheparinisation.
Early Diagnosis of Spinal Haematoma Following CNB.
Should SH occur, the symptoms include a severe, radiating back pain which is radicular in character and associated with sensory and motor deficit. The sensory block, muscle weakness, and urinary retention outlast the expected duration of CNB. Paraplegia develops over the ensuing 14.5+/-3.7hr. The time span between the development of a SH causing neurological deficit and surgical decompression should be less than 8hr.
References:
1. Vandermeulen EP et al. Anticoagulant and Spinal-Epidural Anesthesia. Anesth Analg 1994;79:1165-77
2. Spencer L et al. Epidural anesthesia and analgesia their role in postoperative outcome. Anesthesiology 82;6:1474-1506.
3. Horlocker TT, et al. Preoperative antiplatelet therapy does not increase the risk of spinal hematoma associated with regional anesthesia. Anesth Analg 1995;80:303-9.