Challenges of Neuraxial Anesthesia (Obstetrics)

Absolute Contraindications to Neuraxial Analgesia

  1. patient refusal
  2. infection at insertion site
  3. coagulopathy
  4. hypovolemic shock

Hypotension is the most common complication and can be avoided/attenuated with hydration and positioning (left-ward placement of uterus, avoid supine position) [Stoelting RK. Basics of Anesthesia, 5th ed. Elsevier (China) p. 488, 2007].  Excessive level of anesthesia may occur, and is treated with fluids, pressors, and intubation. Systemic toxicity is a rare complication, but if it occurs, delivery should not be attempted at the expense of maternal resuscitation, as the neonate has difficulty excreting local anesthetics and may not particularly benefit from delivery.  Maternal cardiac arrest does sometimes occur – if resuscitation is unsuccessful, delivery within 5 minutes maximizes the neonates survival and may improve the mother’s chances as afterload and metabolic requirements are reduced.

Sedation/Analgesia and Labor Progression

Some authors believe that excessive sedation or premature analgesia can prolong the latent phase of labor.  Others, who hold an increasingly popular view, believe that requirement for sedation/analgesia is a sign of impending latent phase prolongation but not a cause. Furthermore, some authors believe that the catecholamine response to pain inhibits uterine contractions, as has been suggested by animal (rat) data [Segal S et al. Anesthesia & Analgesia 87: 864, 1998]

The debate about the utility of early epidurals was put to rest by Wong’s group, who conducted a RCT of 750 nulliparous women, randomized to thecal fentanyl at first instance of pain vs. IV pain medicine at first instance (early group received epidural analgesia at the second request for analgesia but in the late group not until cervical dilatation achieved 4.0 cm or a third request for analgesia was made), the early epidural group offered the following advantages – “The median time from the initiation of analgesia to complete dilatation was significantly shorter after intrathecal analgesia than after systemic analgesia (295 minutes vs. 385 minutes, P<0.001), as was the time to vaginal delivery (398 minutes vs. 479 minutes, P<0.001). Pain scores after the first intervention were significantly lower after intrathecal analgesia than after systemic analgesia (2 vs. 6 on a 0-to-10 scale, P<0.001). The incidence of one-minute Apgar scores below 7 was significantly higher after systemic analgesia (24.0 percent vs. 16.7 percent, P=0.01)” [Wong CA et al. N Engl J Med 352: 655, 2005]

Body Temperature and Neonatal Septic Workups

Some data suggests that epidurals increase core body temperature after 5 hours and that this could lead to increased septic workups in neonates, however a retrospective study of 922 primiparous women who received LEA (compared to 255 women received parenteral analgesics) showed no appreciable difference [Kaul B et al. Anesth Analg 93: 986, 2001; FREE Full-text at Anesthesia & Analgesia]