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Obstetric analgesia: back to the future?

One hundred and fifty years ago, on 7 April 1853, John Snow administered chloroform to Victoria, Queen of England, for childbirth. The Queen ‘blessed the chloroform’ after a happy delivery and began the age of analgesia for women in labor. In 1858, in his fundamental book On Chloroform, Snow wrote of the differences beween analgesia and anesthesia, showing profound knowledge of the concentrations of delivered anesthetics and the resultant effects on the uterus and the newborn. During the birth of her ninth child, Queen Victoria accepted chloroform again. This action aided the acceptance and respectability of labor analgesia; in 1847 James Simpson, Professor of Midwifery in Edinburgh, Scotland, introduced ether for vaginal delivery despite the considerable resistance of church leaders. Use of nitrous oxide dates from 1881, when Stanislav Klikovich, a Polish physician living in Russia, found that it was a safe and effective anesthetic, with no interference with uterine contraction. Although a mixture of nitrous oxide and oxygen was re-introduced in the 1940s and 1950s, it was not until 1961 that Tunstall described the use of premixed nitrous oxide–oxygen for labor. In the UK the adoption of nitrous oxide and oxygen in a premixed form began in 1963. Now, nitrous oxide is the world’s most commonly used inhaled agent during labor and delivery. During the decade 1975–85 in the USA, nitrous oxide was used for 6% of deliveries, while, in the UK, Finland, Canada, Australia and New Zealand, it is used by 50–80% of women1. Unfortunately, only a few studies have proved the efficacy of nitrous oxide during labor2,3, and others have shown no advantages of nitrous oxide over placebo4. For this reason, inhaled anesthetics have seldom been considered an option for the parturient. To date, epidural and combined spinal and epidural analgesics are the gold standard during labor. ‘First-class delivery’, that is labor that is pain-free, is produced by a combination of the skills of the anesthesiologist, the availability of specific equipment and personnel, and acceptance among physicians. Many researchers have attempted to demonstrate that epidural analgesia did not raise the incidence of Cesarean section, but none have studied the incidence of an avoided surgical procedure because of epidural analgesia. The development of regional anesthetic techniques, along with new drugs and advanced devices, offers the opportunity of a serene delivery in an equipped environment. However, despite the efforts made to improve the techniques, it is not certain that epidural and combined spinal–epidural analgesia present no risk to the parturient. Scott and Hibbard reported a rate of permanent major neurological damage of around 1/125 000 after epidural analgesia for labor and delivery5. Are these numbers acceptable? The majority of parturients, if properly informed, would not accept even a small risk for their labor and delivery6. They would probably prefer a safer, but less effective, alternative for preventing pain during uterine contractions and cervical dilatation than a ‘first-class delivery’ technique. The complications of epidural analgesia are acceptable for surgical procedures in ill subjects, but they are not adequate for physiological delivery. Labor is not an illness, and every woman shows a variable acceptance of pain, because she knows that, in a brief time, she will embrace her baby. The ideal inhalational anesthetic agent must display a non-pungent smell and adequate potency for keeping the patient awake, with intact laryngeal reflexes. In clinical practice, the introduction of more potent anesthetics, characterized by fast onset and offset, could open new perspectives in the search for a valid alternative to invasive techniques. Intermittent administration of sevoflurane, an ether introduced in operative theaters since 1993, was successful in 50 parturients without major or minor complications7. Although these numbers are inconclusive regarding efficacy, potential adverse outcomes and safety, these results are being confirmed by other promising research in progress. Inhaled analgesia could constitute an effective technique. It is easy to administer even without special training and, with some precautions, without the continuous presence of an anesthesiologist. Sevoflurane The Journal of Maternal–Fetal and Neonatal Medicine 2003;14:6–7