Ideally, an operative procedure is initiated only after it has and that adequate ventilation can be accomplished. Even with an abnormal fetal heart rate pattern, cesarean delivery initiation will only serve to complicate matters if there is diicult or failed intubation. Frequently, the woman must be allowed to awaken and a diferent technique used, such as an awake intubation or regional analgesia.
Following failed intubation, the woman is ventilated by mask and cricoid pressure is applied to reduce the aspiration risk. Surgery may proceed with mask ventilation, or the woman may be allowed to awaken. In those cases in which the woman has been paralyzed and ventilation cannot be reestablished by insertion of an oral airway, by laryngeal mask airway, or by use of a iberoptic laryngoscope to intubate the trachea, then a life-threatening emergency exists. To restore ventilation, percuraneous or even open cricothyrotomy is performed and jet ventilation begun. Failed intubation drills have been recommended to optimize the response to such an emergency.
With the endotracheal tube secured, anesthesia is maintained with a halogenated agent, typically mixed with air or nitrous oxide. he most commonly used inhalational anesthetics in the United States include deslurane and sevolurane. Both have low solubility in blood and fat. As a result, they ofer faster onset and clearance than more traditional gases such as isolurane. In addition to providing amnesia, they produce profound uterine relaxation when given in high concentrations. his is advantageous when relaxation is a requisite, such as for internal podalic version of the second twin, for breech decomposition, or for replacement of the acutely inverted uterus. That said, unless the woman is alread) under general anesthesia, intravenous nitroglycerine is preferred by many in such situations.
he endotracheal tube may be safely removed only if the woman is conscious to a degree that enables her to follow commands and is capable of maintaining oxygen saturation with spontaneous respiration. Consideration is given to emptying the stomach via a nasogastric tube before extubation. As induction has become safer, extubation may now be relatively more perilous. Of 15 anesthesia-related deaths of pregnant women from 1985 to 2003 in Michigan, none occurred during induction. Five resulted from hypoventilation or airway obstruction during emergence, extubation, or recovery (Mhyre, 2007).
Massive gastric acidic inhalation may cause pulmonary insufficiency from aspiration pneumonitis. In the past, this was the most common cause of anesthetic deaths in obstetrics and therefore deserves special attention. To minimize this risk, antacids are given rourinely, intubation is accompanied by cricoid pressure, and regional analgesia is employed when possible.
According to the American Society of Anesthesiologists Task Force on Obstetrical Anesthesia (2016) and the merican College of Obstetricians and Gynecologists (2017b), data are insuicient regarding fasting times for clear liquids and the risk of pulmonary aspiration during labor. Recommendations are that modest amounts of clear liquids such as water, clear tea, black cofee, carbonated beverages, and pulp-free fruit juices be allowed in uncomplicated laboring women (Chap 22, p. 437). Obvious solid foods are avoided. A fasting period of 6 to 8 hours for solid food is recommended for uncomplicated parturients prior to undergoing elective cesarean delivery or puerperal tubal ligation.