Unexpectedly extensive conduction blocks in obstetric epidural analgesia

Effects of epidural fentanyl on speed and quality of block for emergency cesarean section in extending continuous epidural labor analgesia using ropivacaine and fentanyl

We performed a prospective, randomized, and double-blind study comparing the top-up effects of 2% lidocaine/100 microg fentanyl/epinephrine (n=31) and 2% lidocaine/saline/epinephrine (n=30) when extending an epidural labor analgesia using low-dose ropivacaine and fentanyl. Survival analysis for the sensory blocks to the T4 level showed no statistically significant differences in onset time to T4 between the 2 groups. Onset times (min) to T4-sensory blocks for cold and pinprick were not different between the two groups. However, median maximum sensory level in the lidocaine-fentanyl group (T1 for cold and T2 for pinprick) was significantly higher than that in the lidocaine-saline group (T3 and T4, respectively). The lidocaine-fentanyl group exhibited less visceral pain (6.5% vs. 36.7%), less supplementation of lidocaine (6.5% vs. 43.3%), and less nausea (6.5% vs. 26.7%) compared with the lidocaine-saline group during the intraoperative period. It is concluded that adding fentanyl to 2% lidocaine does not speed up the onset of the block when the onset is tested with cold or sharp pinprick but improves the quality of analgesia with fewer side effects in emergency top-up for cesarean section.

Reversal of an Unintentional Spinal Anesthetic by Cerebrospinal Lavage

In this case report, we describe the use of cerebrospinal fluid lavage as a successful treatment of an inadvertent intrathecally placed epidural catheter in a 14-yr-old girl who underwent a combination of epidural anesthesia and general anesthesia for orthopedic surgery. In this case, a large amount of local anesthetic was injected (the total possible intrathecal injection was 200 mg of lidocaine and 61 mg of bupivacaine), resulting in apnea and fixed dilated pupils in the patient at the end of surgery. Twenty milliliters of cerebrospinal fluid was replaced with 10 mL of normal saline and 10 mL of lactated Ringer's solution from the "epidural" catheter. Spontaneous respiration returned 5 min later, and the patient was tracheally extubated after 30 min. No signs of neurological deficit or postdural puncture headache were noted after surgery.

IMPLICATIONS

Cerebrospinal lavage may be a helpful adjunct to the conventional supportive management of patients in the event of an inadvertent total spinal.

The combined spinal–epidural technique

In recent years, the use of regional anaesthesia techniques for surgery, obstetrics and post operative pain management have increased in popularity. The combined spinal-epidural (CSE) technique has attained widespread popularity for patients undergoing major surgery below the umbilicus who may require prolonged and effective postoperative analgesia. The CSE technique is now well established in several institutions. This chapter includes the clinical experience, advantages and potential problems, and discusses future perspectives of the CSE technique.

The combined spinal-epidural technique

Epidural and spinal blocks are well-accepted regional techniques, but they have several disadvantages. The CSE technique can reduce or eliminate the risks of these disadvantages. CSE block combines the rapidity, density, and reliability of the subarachnoid block with the flexibility of continuous epidural block to extend duration of analgesia. The CSE technique is used routinely at many institutions, particularly for major orthopedic surgery and in obstetrics. It has been used in tens of thousands of patients without any reports of major problems. Although at first sight the CSE technique appears to be more complicated than epidural or spinal block alone, intrathecal drug administration and siting of the epidural catheter are both enhanced by the combined, single-space, needle-through-needle method. Concerns about the epidural catheter entering the theca via the small puncture hole are now considered to be unfounded, but as with all epidural catheter techniques, vigilant monitoring of the patient during and after any injection is paramount. CSE is an effective way to reduce the total drug dosage required for anesthesia or analgesia. The intrathecal injection achieves rapid onset with minimal doses of local anesthetics and opioids, and the block can be prolonged with low-dose epidural maintenance administration. In addition, the sequential CSE method can be used to extend the dermatomal block with minimal additional drugs or even saline. Reduction in total drug dosage has made truly selective blockade possible. Many studies have confirmed that low-dose CSE with local anesthetic and opioid, or low-dose epidural block alone, will provide effective analgesia with minimal motor and proprioceptive block. Such neurologic selective blockade has made it possible for most patients to walk and bear down normally in labor or postoperatively. There remains concern about the risk of infection being increased when the CSE technique is used in place of epidural block alone. Despite a recent flurry of reports of meningitis with CSE procedures, there is no evidence the CSE block is more hazardous than epidural or subarachnoid block alone. Arguably, the single-space, needle-through-needle CSE technique will continue to improve with new needle designs and other advances to improve further the success rate and reduce complications, such as neurotrauma, PDPH, and infection. Over the past decade it has become clear that the CSE technique is a significant advance in regional blockade.

Bilateral trigeminal nerve palsy during an extensive lumbar epidural block

A rare case of trigeminal nerve blockade arising in the course of obstetric lumbar epidural anaesthesia is described. There was extensive bilateral spread of nerve-block up to the C4 level with respiratory distress after top-up for caesarean section, and subsequent epidurography revealed high epidural spread of contrast. The mechanism of the trigeminal nerve palsy was the source of some controversy, particularly as to whether intracranial spread of local anaesthetic had occurred, possibly following accidental subdural or subarachnoid injection.

Surgical anaesthesia for Caesarean section with a subdural catheter

PURPOSE

This case report describes a radiologically proven subdural catheter placed in a term parturient, which consistently performed as an epidural catheter for both labour analgesia as well as surgical anaesthesia.

CLINICAL FEATURES

The patient was a 26-yr-old, 52.7 kg. 140 cm healthy woman with a 39 wk intrauterine pregnancy. At initiation of epidural blockade, and for many hours throughout labour, an appropriate volume and concentration of local anaesthetic achieved an appropriate analgesic sensory level (10 ml bupivacaine 0.25%, bilateral T10 sensory level). However, for Caesarean section, while an appropriate volume and concentration of local anaesthetic achieved an appropriate surgical anaesthetic sensory level (15 ml bupivacaine 0.5%, bilateral T4 sensory level), there was no demonstrable motor blockade (0 on the Bromage scale). The Caesarean section was performed without incident, and without the need for supplemental intravenous opioids or anxiolytics.

CONCLUSION

We report the case to question the commonly held beliefs of subdural catheter presentation. We questioned the catheter position, and proved its subdural placement, only after larger volumes of higher concentration local anaesthetic did not achieve expected goals. It is possible that a high percentage of epidural catheters may be subdural, unbeknownst to the practitioner.

Subdural block--further points

An obstetric epidural performed for analgesia showed a changing pattern of neurological block. The original features suggestive of a subdural block were complicated when aspiration of cerebrospinal fluid from the catheter became possible. Subsequent management as a continuous subarachnoid catheter allowed delivery.

A new epidural catheter. Closer eyes for safety?

A new design of epidural catheter with three lateral eyes placed in close proximity to its closed end is described. Prototype models of this catheter were tested in 200 obstetric and surgical patients. In a single-blind randomised study it was found to be easy to insert and highly satisfactory in use, when compared to the current catheter type, with three widely spaced lateral eyes. It is hoped that the close spacing of the eyes will eliminate the complication of multicompartment block, as seen with earlier multihole catheters, and improve the safety of epidural block.

Cardiorespiratory arrest following combined spinal epidural anaesthesia for caesarean section

A 31-year-old woman had an elective Caesarean section under combined spinal/epidural anaesthesia. At the end of the operation, diamorphine 2.5 mg in 5 ml of 0.25% bupivacaine plain was injected through the epidural catheter. Forty minutes after this, the patient had a cardiorespiratory arrest in an ordinary postnatal ward.

Accidental total spinal block: a complication of an epidural test dose

A case is presented of a 36-yr-old parturient who developed a total spinal block after an epidural test dose. After placement of an epidural catheter and confirming negative aspiration for blood or CSF, 3 ml lidocaine 1.5% (45 mg), with 1:200,000 epinephrine (15 micrograms) was injected via the catheter over 30 sec. Within two minutes the patient developed hypotension and extensive sensory and motor block including respiratory paralysis and aphonia. She remained fully conscious and alert and spontaneous respiration recommenced in five minutes. A live healthy infant was delivered by emergency Caesarean section shortly afterwards under general anaesthesia and the mother recovered completely without any untoward sequelae.

Extending epidural blockade for emergency caesarean section Evaluation of 2% lignocaine with adrenaline

Pre-existing epidural analgesia was rapidly extended in 36 consecutive patients presenting for emergency caesarean section by using 20 ml of 2% lignocaine + 1/200,000 adrenaline freshly prepared given by slow bolus injection. Despite a wide range of initial analgesic sensory levels the technique produced blocks that were dense with adequate anaesthesia for surgery in all patients within 12.5 min. The plasma local anaesthetic concentrations were well below the toxic range. Neonatal condition was good.

Epidural analgesia in labour: constant infusion plus patient-controlled boluses

A randomised, single-blind study to investigate patient-controlled epidural analgesia during labour was conducted using a solution of low-dose bupivacaine-fentanyl. Two groups (n = 25 in each) received a constant infusion supplemented by patient demand boluses, and midwife-administered boluses if required, the size of the infusion and patient increments varying between groups. The quality of analgesia, as assessed by pain scores and patient ratings, was high and participant acceptability very high in both groups. Fourteen per cent of participants were withdrawn due to cephalad extension of block to T5 or supplementary bolus requirements outside the study protocol. Epidural side-effects were not troublesome and drug dose utilisation was low. Significantly greater pain relief (P less than 0.04) three hours after commencing patient-controlled epidural analgesia and a trend to fewer women requiring more than two supplementary midwife-administered boluses (P = 0.11) was seen in the group receiving a higher infusion rate. This group used significantly more bupivacaine (P less than 0.04) and fentanyl (P less than 0.001), but this did not appear to be clinically important with respect to degree of motor block or side-effects. Patient-controlled epidural analgesia appears to be an effective and well accepted method of obstetric analgesia and warrants further investigation.