Labor is different for every woman, and the methods chosen for pain relief will depend on the obstetric/medical condition, the techniques locally available, and the preference of the patient. Neuraxial analgesia is the most effective method. However, there are many mothers who wish to avoid intervention or in whom the technique is contraindicated or impossible to perform. Contraindications for regional labor analgesia may include coagulopathy, local infection, allergy to local anesthetics, and uncorrected hypovolemia. Difficulties in placing epidurals can arise from anatomical deformities, postsurgical spine corrections, and obesity. For this group of parturients, alternative methods may be required and often will involve alternatives to neuraxial analgesia such as nonpharmacologic and pharmacologic techniques.
NONPHARMACOLOGIC LABOR ANALGESIA
Antenatal childbirth education is a critical first step for a labor analgesia plan. This dates back to the 1930s, when Grantley Dick-Read in England suggested that childbirth did not require medical intervention if the mother was adequately prepared. In the 1950s, Dr Lamaze, a French obstetrician, developed psychoprophylaxis. This technique involves education regarding the physiologic process of labor and delivery with trained relaxation response to contractions. The technique also uses patterned breathing with two goals: increasing maternal oxygenation and interfering with pain signal transmission to the cerebral cortex from the uterus. Although antenatal education will undoubtedly alleviate some of the fear and anxiety associated with labor, it is unrealistic to suggest that it will lead to painless childbirth for the majority of mothers.
Coming from the Greek word for “servant or slave,” a doula is a woman trained to attend to the emotional and physical needs of the parturient. Research has suggested that continuous support and encouragement from doulas throughout labor reduces the need for epidural, analgesic interventions, and the rate of operative deliveries.1
Transcutaneous Electrical Nerve Stimulation
Transcutaneous electrical nerve stimulation (TENS) is a noninvasive method using surface electrodes placed over the T10-L1 dermatomes and is most effective in early labor. A second set of electrodes can be placed over the S2-S4 dermatomes for second stage pain relief. Conventional TENS utilizes low-intensity, high-frequency biphasic pulsed currents in a repetitive manner with pulse durations of 50 to 250 ms and pulse frequencies of 1 to 200/s. The efficacy of TENS relates to the gate control theory of pain. The electrical current is postulated to reduce pain via nociceptive inhibition at a presynaptic level in the dorsal horn of the spinal cord, thus limiting central transmission of pain impulses. The electrical cutaneous stimulation preferentially activates low-threshold myelinated nerve fibers. This afferent activity inhibits propagation of nociception in small unmyelinated C fibers by blocking transmission to the target cells located within laminae 2 and 3 of the substantia gelatinosa of the dorsal horn.2 Another proposed theory is that TENS enhances the release of endorphins ...