General and Local Anesthetics and Muscle Relaxants

This chapter describes the local anesthetics and muscle relaxants used in surgery in pregnancy. Muscle relaxants, often used as adjuncts to most surgical procedures performed under general anesthesia, can also reach the fetus. Local disinfectants are generally poorly absorbed through the skin, depending on its integrity, and hence, these disinfectants do not usually reach the fetus. Anesthetic complications involving compromise of the mother's breathing or circulation (that is, pulmonary hypertension) or anesthetic-associated malignant hyperthermia, which may have adverse consequences for the fetus, are described in the chapter. The chapter also explains halogenated inhalation agents for general anesthesia. Halothane, fluothane, isoflurane, desflurane, enflurane, and sevoflurane are halogenated inhalation agents with similar clinical effects. Nitrous oxide is a slow-acting gas with good analgesic and limited anesthetic effects, which may be combined with other anesthetics and/or muscle relaxants to obtain complete anesthesia. Injectable anesthetics may also be used. These include etomidate, ketamine, methohexital, propofol, and thiopentone. Local anesthetics include lidocaine, bupivacaine and ropivacaine, and ethyl chloride (chloroethane). The chapter then discusses epidural and spinal analgesia/anesthesia in pregnancy. The commonly used muscle relaxants are pancuronium, atracurium, vecuronium, and suxamethonium. The chapter emphasizes that none of the commonly used anesthetics produces an increase in congenital malformations. Finally, the dangers of occupational exposure to inhalation anesthetics are highlighted.