Epidural Blood Patch

Anatomy and Physiology

The epidural space is bounded by the dural meninges anteriorly, the ligamentum flavum posteriorly and the sides of the vertebral walls laterally. It extends from the foramen magnum to the sacral hiatus. Its contents are tiny arteries and lymphatics, epidural fat, and a network of small valveless veins (Batson plexus). The epidural "space" is more of a potential space; a series of discontinuous compartments that open up when injected with liquid or air.[6]

Indications

Epidural blood patch (EBP) is indicated for the treatment of post-dural puncture headache in people who don't respond to conservative treatment (rest, IV hydration, PO analgesics, IV/PO caffeine) and who will not tolerate the 7 to 10 days in which most dural puncture headaches resolve.

Contraindications

Contraindications for EBP include anticoagulation/coagulopathy, infection at the injection site, and patient refusal or lack of cooperation.

Equipment

Equipment required for EBP includes a standard epidural kit and an 18-gauge or 20-gauge angiocatheter from which to draw autologous blood in a sterile fashion. The author prefers to place the catheter and cap it off and saline flush to expedite autologous blood draw once access to the epidural space is achieved.

Personnel

Although EBP can be performed by a single operator, it usually requires a second operator for a sterile blood draw and, possibly, a third assistant to help with patient positioning.

Preparation

Following an explanation of the procedure and obtaining informed consent, the patient is placed in a lateral or seated position. A seated position will exacerbate symptoms, and some patients will not tolerate this for more than a few minutes, if at all. The back injection site, either from a previous dural puncture or a vertebral interspace one above or below, is sterilely prepped and draped as well as the extremity from which blood is to be drawn.

Technique or Treatment

The epidural space is identified in the standard fashion using loss-of-resistance to air or saline. In particularly difficult instances the use of C-arm radiography or ultrasound guidance may be used. Once the placement of the needle tip of the 17-gauge epidural needle is confirmed, approximately 20 mL of autologous blood is drawn from the patient in a sterile fashion. The blood is injected slowly (30 to 60 seconds) to create a blood patch. The introduction of blood into the epidural space may produce discomfort and cramping occasionally limiting the volume of injected blood. Smaller injected volumes will often work in creating a blood patch. Reports have indicated successful EBP for PDPH with as little as 5 mL of autologous blood (range 5 to 25 mL); however, most practitioners will use approximately 20 mL if possible.

Complications

The most frequent and problematic complications of EBP include failure (15 to 20%), worsening of PDPH by inadvertently creating additional dural rent(s), back pain, and infection. Mild to moderate back pain is commonly reported. This is self-limited, generally resolving in days and preferable to the discomfort of a PDPH. Also, patients need to be made aware of signs and symptoms of infection at the injection site: fever, malaise, erythema, or purulence as injected blood may serve as a nidus for infection. This requires urgent evaluation and care.[7][8][9]

Clinical Significance

As most cases of PDPH's resolve spontaneously within 7 to 10 days, some patients may opt for conservative treatment rather than EBP. These include limiting upright position, hydration, oral analgesics, and intravenous or oral caffeine. Caffeine is a cerebral vasoconstrictor. It is administered as 500 mg sodium caffeine benzoate in 1000 mL of NS or LR over 1 to 2 hours. This, however, generally produces short-term relief. A patient who chooses conservative therapy should keep well hydrated and consume caffeine-containing beverages and oral analgesics as necessary at home.

The majority of patients who elect to have EBP are those that cannot minimize activity, for example, recent parturients with newborns or younger patients. Also, those patients that are extremely symptomatic (some cephalgia even when supine and cannot tolerate any degree of upright positioning, tearful or crying at rest, photophobia) will likely consent to EBP with or without conservative treatment.

It is important to keep in mind that not all headaches, even if the patient is a post-dural puncture, are PDPHs, and this must be considered in the workup before performing EBP. Furthermore, in mildly symptomatic patients, for example, mild cephalgia when standing 15 to 20 minutes will spontaneously resolve with conservative therapy, and may be preferable to risking a second, large-bore (17-gauge) dural puncture, back pain, and the possibility of infection.

An epidural blood patch is a highly effective way to treat a specific subset of post-dural puncture headache patients. It is an elective procedure that carries a relatively low degree of risk.

Enhancing Healthcare Team Outcomes

Once PDPH has developed, healthcare workers including nurse practitioners, physician assistants, and primary care physicians should educate the patients. The majority resolve within 2 weeks. Other supportive measures include limiting upright position, hydration, oral analgesics, and intravenous or oral caffeine. Caffeine is a cerebral vasoconstrictor. It is administered as 500 mg sodium caffeine benzoate in 1000 mL of normal saline or lactated Ringer over 1 to 2 hours. This, however, generally produces short-term relief. A patient who chooses conservative therapy should keep well hydrated and consume caffeine-containing beverages and oral analgesics as necessary at home.

The majority of patients who elect to have EBP are those that cannot minimize activity, for example, recent parturients with newborns or younger patients. Also, those patients that are extremely symptomatic (some cephalgia even when supine and cannot tolerate any degree of upright positioning, tearful or crying at rest, photophobia) will likely consent to EBP with or without conservative treatment. It is important to tell the patient that EBP is not 100% effective.[10]

An interprofessional team approach to caring for these patients will produce the best results. [Level 5]