Epidural - Complications

Complications

These include:

• failure to achieve analgesia or anaesthesia occurs in about 5% of cases, while another 15% experience only partial analgesia or anaesthesia. If analgesia is inadequate, another epidural may be attempted.
  • The following factors are associated with failure to achieve epidural analgesia/anaesthesia:
    • Obesity
    • Multiparity
    • History of a previous failure of epidural anaesthesia
    • History of regular opiate use
    • Cervical dilation of more than 7 cm at insertion
    • The use of air to find the epidural space while inserting the epidural instead of alternatives such as saline or lidocaine
• Accidental dural puncture with headache (common, about 1 in 100 insertions). The epidural space in the adult lumbar spine is only 3-5mm deep, which means it is comparatively easy to cross it and accidentally puncture the dura (and arachnoid) with the needle. This may cause cerebrospinal fluid (CSF) to leak out into the epidural space, which may in turn cause a post dural puncture headache (PDPH). This can be severe and last several days, and in some rare cases weeks or months. It is caused by a reduction in CSF pressure and is characterised by postural exacerbation when the subject raises his/her head above the lying position. If severe it may be successfully treated with an epidural blood patch (a small amount of the subject's own blood given into the epidural space via another epidural needle which clots and seals the leak). Most cases resolve spontaneously with time. A change in headache pattern (e.g., headache worse when the subject lies down) should alert the physician to the possibility of development of rare but dangerous complications, such as subdural hematoma or cerebral venous thrombosis.

• Delayed onset of breastfeeding and shorter duration of breastfeeding: In a study looking at breastfeeding 2 days after epidural anaesthesia, epidural analgesia in combination with oxytocin infusion caused women to have significantly lower oxytocin and prolactin levels in response to the baby breastfeeding on day 2 postpartum, which means less milk is produced. In many women undergoing epidural analgesia during labour oxytocin is used to augment uterine contractions.
• Bloody tap (about 1 in 30-50). It is easy to injure an epidural vein with the needle. In people who have normal blood clotting, it is extremely rare (e.g. 1 in 100,000) for problems to develop. However, people who have a coagulopathy may be at risk of epidural hematoma.

• Catheter misplaced into a vein (uncommon, less than 1 in 300). Occasionally the catheter may be misplaced into an epidural vein, which results in all the anaesthetic being injected intravenously, where it can cause seizures or cardiac arrest in large doses (about 1 in 10,000 insertions). This also results in block failure.
• High block, as described above (uncommon, less than 1 in 500).
• Catheter misplaced into the subarachnoid space (rare, less than 1 in 1000). If the catheter is accidentally misplaced into the subarachnoid space (e.g. after an unrecognised accidental dural puncture), normally cerebrospinal fluid can be freely aspirated from the catheter (which would usually prompt the anaesthetist to withdraw the catheter and resite it elsewhere). If, however, this is not recognised, large doses of anaesthetic may be delivered directly into the cerebrospinal fluid. This may result in a high block, or, more rarely, a total spinal, where anaesthetic is delivered directly to the brainstem, causing unconsciousness and sometimes seizures.
• Neurological injury lasting less than 1 year (rare, about 1 in 6,700).
• Epidural abscess formation (very rare, about 1 in 145,000). Infection risk increases with the duration catheters are left in place, although infection was still uncommon after an average of 3 to 5 days' duration.
• Epidural haematoma formation (very rare, about 1 in 168,000).
• Neurological injury lasting longer than 1 year (extremely rare, about 1 in 240,000).
• Paraplegia (1 in 250,000).
• Arachnoiditis (extremely rare, fewer than 1000 cases in the past 50 years)
• Death (extremely rare, less than 1 in 100,000).

The figures above relate to epidural anaesthesia and analgesia in healthy individuals.

Evidence to support the assertion that epidural analgesia increases the risk of anastomotic breakdown following bowel surgery is lacking.

Controversial claims:

• "epidural anaesthesia and analgesia significantly slows the second stage of labour". The following are a few plausible hypotheses for this phenomenon:
  • The release of oxytocin, which stimulates the uterine contractions that are needed to move the child out through the vagina, may be decreased with epidural anaesthesia or analgesia due to factors involving the reduction of stress, such as:
    • Epidural analgesia may reduce the endocrine stress response to pain
      • Diminished release of epinephrine from the adrenal medulla slows the release of oxytocin
    • Diminished blood pressure, accommodated by both decreased stress and less adrenal release, may decrease the release of oxytocin as a natural mechanism to avoid hypotension. It may also affect the heart-rate of the fetus.
• Still plausible (though less studied without a documented reproduction in a laboratory setting) are the effects of the reclined position of the woman on the fetus, both immediately prior to and during delivery.
  • These hypotheses generally posit an interaction with the force of gravity on fetal position and movement, as demonstrated by the following examples:
    • Transverse or posterior fetal positioning may become more likely as a result of the shift in orientation to gravitational force.
    • Diminished gravitational assistance is present in building pressure for commencing delivery and for progressing the fetus along the vagina.
  • It is important to note that the orientation of the fetus can be established by ultrasonic stenography prior to, during, and after the administration of an epidural block. This would seem a fine experiment for testing the first hypothesis. It should also be noted that the majority of fetal movement through the vagina is accomplished by cervical contractions, and so the role of gravity and its force relative to the position of the woman in labour (on delivery, not development) is difficult to establish.
• There has been a good deal of concern, based on older observational studies, that women who have epidural analgesia during labour are more likely to require a cesarean delivery. However, the preponderance of evidence now supports the conclusion that the use of epidural analgesia during labour does not have a significant effect on rates of cesarean delivery. A Cochrane review of twenty trials involving a total of 6534 women estimated that women undergoing labour using epidural analgesia were only slightly more likely (1.07 times as likely) to undergo cesarean delivery than those in whom epidural analgesia was not used.

Epidural analgesia does increase the duration of the second stage of labour by 15 to 30 minutes and may increase the rate of instrument-assisted vaginal deliveries as well as that of oxytocin administration. Some people have also been concerned about whether the use of epidural analgesia in early labour increases the risk of cesarean delivery. Three randomized, controlled trials showed that early initiation of epidural analgesia (cervical dilatation, <4 cm) does not increase the rate of cesarean delivery among women with spontaneous or induced labour, as compared with early initiation of analgesia with parenteral opioids.