Analgesic medications may be used in an inhaled form during labor. Nitrous oxide is the most commonly used inhaled analgesic. With intermittent use, it can provide adequate analgesia for some women, yet proper dosing can be difficult to achieve.
Administration of inhaled medications requires use of a device that limits the concentration of the drug administered. In addition, trained personnel must be available to monitor the device at regular intervals and to perform endotracheal intubation (the use of a tube through the nose or mouth into the trachea to maintain the airway) if too much drug is given and respiratory reflexes are lost.
The effectiveness of inhaled analgesics in treating pain during labor varies greatly between studies. Since there is no clear evidence of their effectiveness, most obstetric anesthesiologists have abandoned their use. The main role for inhaled agents is during the induction of general anesthesia, which can be required during an emergency or elective cesarean section in women with specific medical problems.