Page 142 Guide to Pain Management in Low-Resource Settings

130 Katarina Jankovic

Accidental intravascular injection usually oc- mL), low-concentration formulation of bupivacaine/fen-
curs as a result of accidental placement of the epidural tanyl will initiate good analgesia. Additional 3-mL dos-
catheter into an epidural vein. Th us, even a small dose es are given if pain persists after 15 minutes. Another
can produce central nervous system eff ects. Care should reasonable option for providing second-stage analgesia
be taken to avoid accidental placement in the fi rst place is to perform a spinal or combined spinal and epidural
with repeated aspiration tests and applying only smaller (CSE) using a local anesthetic-opioid combination (e.g.,
doses of local anesthetics at any one time (avoiding large 2 mg isobaric bupivacaine intrathecally). Th is method
volumes of bolus applications). Unexpected high block is has a rapid onset, so that the patient is comfortable and
often the result of the catheter being placed advertently can even be ready for cesarian section within 5 minutes.
into the subarachnoid space. Low-dose local anesthetic/
opioid mixtures, if given accidently intrathecally, will not If vaginal delivery is unsuccessful
produce total spinal block with respiratory depression, and caesarian section is necessary,
but can cause motor block and dysesthesias and will
how should one proceed with intra-
frighten the patient (and the physician). For intrathecal and postoperative analgesia?
(“spinal”) application of local anesthetics, the total dose
of drug injected is more important than the total volume Our patient from the beginning of the chapter has been
in which it is given. A high block can also, very rarely, monitored for fetal heart rate, and the obstetrician is
be the result of a subdural block. Th e subdural space is indicating urgent cesarian section due to fetal distress.
located between the dura and the arachnoidea. While Th en you might think about using spinal instead of gen-
the epidural space extends only up to the foramen mag- eral anesthesia, since it is easy, cheap, safe, and provides
num, the subdural space extends all the way upward. prolonged analgesia.
Th is space can be entered unintentionally at any stage of Over the past 15 years, there has been a large
labor. Subdural block should be recognized by an unex- increase in the number of cesarian sections done under
pected increase in anesthesia level and presentation with regional anesthesia. It is therefore tempting to advocate
slow onset, patchy blockade, minimal sacral analgesia, that general anesthesia is no longer indicated, but cer-
cranial nerve palsies, and a relative lack of sympathetic tain factors must be taken into account when changing
blockade. Subsequent injection of large volumes of local the standard anesthesia technique from general to spi-
anesthetic into the subdural space may rupture the ar- nal anesthesia. It is important to remember that when
achnoidal mater and exert intrathecal eff ects. spinal anesthesia is used, the standard of care cannot be
lower than for general anesthesia.
Is there a “best time” for initiating Th e work-up for the mother having an elective
epidural analgesia? or emergency cesarian section is the same regardless of
the anesthesia plan. Th is must include preoperative fast-
Occasionally, a parturient reaches the second stage of ing, if possible, and preparation of gastric content with
labor before neuraxial analgesia is requested. Th e pa- appropriate antacids. Th e anesthetist must have access
tient may not have wanted an epidural catheter earlier, to all the equipment (including diffi cult airways equip-
or the fetal heart rate tracing or position may necessi- ment) and recovery facilities required for both tech-
tate assisted delivery (e.g., using forceps or vacuum ex- niques.
tractor). Initiation of epidural analgesia is still possible Spinal anesthesia is probably safer (one study
at this point, but the prolonged latency between cathe- calculated 16 times safer) than general anesthesia, pro-
ter placement and start of adequate analgesia may make vided it is performed carefully with good knowledge of
this choice less desirable than a spinal technique. On the maternal physiology. Diffi cult airways and obesity-relat-
other hand, the initiation of an epidural catheter cannot ed edema become less of an issue, but remember that
be done be too early. Th e argument that early catheter a pregnant woman lying supine can become hypoten-
placement may prolong the fi rst stage of labor has not sive, even without augmenting the problem by giving
be confi rmed in studies. If an epidural is used, ultra-low local anesthetics intrathecally. Poor management of this
concentrations of local anesthetics may not be adequate problem can cause severe hypotension, vomiting, and
to relieve the intense pain of the second stage. Adding 3 loss of consciousness, which can lead to aspiration of
mL 0.25% bupivacaine to the standard high-volume (20 gastric contents.