Injection of blood into the epidural space as a treatment for postdural puncture headache (PDPH) was first suggested in the 1960s, following the observation that the incidence of PDPH was lower when dural tap followed a bloody tap. In fact, this relationship was later found not to be so, but epidural blood patch (EBP) has become widely accepted as the gold- standard treatment for PDPH, despite early fears about adverse effects.
The mechanism of action of EBP is uncertain. Traditional teaching is that the blood seals the dural hole, preventing further leakage of cerebrospinal fluid. However, an alteration of cerebrospinal haemodynamics by EBP has been suggested, accounting for EBP’s immediate effect and the observation that lumbar EBP is effective even following cervical dural puncture.
Problems and special considerations
The optimal timing for the performance of an EBP remains controversial. Previous studies have identified a higher failure rate of EBP in patients in whom the initial procedure was performed within the first 24-96 hours of the onset of PDPH, while other studies have demonstrated a favourable outcome when EBP was performed more than 48 hours after the development of the headache. Nevertheless, the need for a repeat procedure in patients who receive an early EBP may be related to the severity of the headache rather than the timing of the intervention, and it is recommended that the intensity of the patient’s symptoms be taken into account when making the decision to perform an early EBP. There are conflicting data on the usefulness of prophylactic EBP (via the catheter after delivery). Problems include the difficulty it might cause with analgesia (e.g. postoperatively), the fact that some women will receive an intervention they may not need, and the possible risk of infection if the catheter is left in place throughout a prolonged labour. Although not routinely recommended, some authors have suggested that the procedure may be considered in patients at high risk of developing PDPH.
Contraindications are those of epidural analgesia generally; in particular the risk of epidural abscess is often quoted if the mother is pyrexial. In that situation, other methods of treating PDPH may be tried; alternatively, prophylactic use of antibiotics has been suggested. Some authorities advocate routine sending of blood for microbiological culture in case bacteraemia is present, although this practice is not universal.
Adverse effects of EBP include those of epidural analgesia (including failure or another dural puncture), back pain, transient nerve root pain and pyrexia. More significant complications such as subdural or intrathecal haematoma with consequent neural compression or arachnoiditis have also been described. Transient bradycardia has been reported, but its significance is uncertain.
Management options
Other causes of postpartum headache should be excluded (see Table 45.1). Two operators are required. While one locates the epidural space in the usual way, the other prepares to draw 20 ml of blood under full aseptic conditions. The blood is injected slowly and the patient is asked to report any unpleasant effects. The interspace at or below the level of the original dural puncture is usually recommended, since injected blood has been shown to track mainly upwards after injection.
One of the controversial issues regarding EBP is the volume of blood to inject. It was thought that the more blood that was injected, the greater the chance of success. Currently, however, the general recommendation is that the volume of blood injected should be individualised, and that injection should cease when the patient reports back pain. This is supported by the findings of a recent retrospective review that demonstrated no added advantage in terms of efficacy (no reduction in the need for a second patch when additional volumes of up to 30 ml of blood were injected).
The patient is usually kept lying for 2-4 hours after EBP (reduced efficacy has been suggested if mobilisation is immediate). The success rate of EBP has been reported as 70-100%; typically, there is complete relief of headache, although some degree of headache may return in up to 30-50% of women. Repeat EBP is sometimes required, rarely more than once. The procedure is performed on an outpatient basis in some units.
The mother should be fully informed of the benefits and risks of EBP (including the lack of proper randomised trials and the possibility of inflicting another dural puncture). A senior anaesthetist should perform the EBP for two reasons: first, the original epidural may have been difficult, and a second dural puncture occurring during EBP would be at best embarrassing; second, the mother has suffered considerable distress and deserves the reassurance of knowing that an experienced anaesthetist is handling her case. Since the headache may return after EBP, she should be invited to contact the anaesthetist if this occurs.
Key points
• Epidural blood patch should be performed by a senior anaesthetist under strict asepsis. 15-20 ml of blood is injected if tolerated.
• The mother is kept supine for 2-4 hours after patching.
• The timing of epidural blood patching should be guided by the severity of the patient’s symptoms.
• Treatment is effective in 70-100% of cases, but headache may recur in 30-50%.
Further reading
Booth JL, Pan PH, Thomas JA, Harris LC, D’Angelo R. A retrospective review of an epidural blood patch database: the incidence of epidural blood patch associated with obstetric neuraxial anesthetic techniques and the effect of blood volume on efficacy. Int J Obstet Anesth 2017; 29: 10-17.
Kokki M, Sjovall, Keinanen M, Kokki H. The influence of timing on the effectiveness of epidural blood patch in parturients. Int J Obstet Anesth 2013; 22: 303-9.
Peralta F, Devroe S. Any news on the postdural puncture headache front? Best Pract Res Clin Anaesthesiol 2017; 31: 35-47.