section epub:type=”chapter” id=”c0255″ role=”doc-chapter”> The intent of this chapter is to provide information on the pregnant patient and fetus undergoing nonobstetric surgery. The physiologic changes, types of surgeries, and perianesthesia nursing care are highlighted and provide the perianesthesia nurse with valuable knowledge to facilitate the appropriate outcomes for the mother and fetus. Aortacaval compression; cesearean delivery; fetal monitoring; postpartum hemorrhage; pregnancy The need for nonobstetric surgery in the pregnant patient may occur at any point in gestation, in approximately 2% of pregnancies or more than 80,000 cases per year in the United States.1–4 Urgent and emergent surgeries should not be delayed because the patient is pregnant; however, elective procedures can wait until after delivery.1–4 The most common operations include those directly related to pregnancy (e.g., cerclage and ovarian cystectomy) and those unrelated to gestation (e.g., appendectomy or cholecystectomy).1–4 More complicated surgical procedures have been successfully performed during pregnancy which include craniotomy, open-heart surgery, and aneurysm repair.2 While regional anesthesia is the preferred anesthetic for cesarean delivery (CD), most nonobstetric surgical procedures are performed under general anesthesia due to the nature of the procedure (e.g., laparoscopic) or patient factors. Regardless of the type of anesthetic used, when caring for the pregnant patient after nonobstetric surgery, the perianesthesia nurse must remember that two patients require nursing care and assessment: mother and fetus. Perianesthesia nursing care should be directed toward emotional support for the mother and avoidance of uterine stimulation that could initiate preterm labor. Also, of prime importance is the prevention of respiratory depression and hypoxia in the mother and maintenance of normal uterine placental blood flow to ensure adequate fetal supply of oxygen and nutrients.2 Definitions Aortocaval Compression (Supine Hypotensive Syndrome) Compression of the aorta and inferior vena cava by the gravid uterus; the extent of compression depends on positioning and gestational age (Fig. 51.1). Aspiration Pneumonitis An inflammatory condition of the lungs and bronchi caused by regurgitation of inhaled stomach contents. Cesarean Section The surgical removal of an infant through an abdominal and uterine wall incision. Cricoid Pressure (Sellick Maneuver) Applying pressure on the cricoid cartilage compresses the esophagus and prevents passive regurgitation, thus minimizing the risk of aspiration when performing a rapid sequence intubation (RSI). Defasciculation Administration of a nondepolarizing muscle relaxant 1 to 3 minutes before the administration of succinylcholine, a depolarizing muscle relaxant, to prevent the muscle twitches that occur after succinylcholine administration. The intended outcome is to reduce the amount of gastric pressure created by the muscle twitches or fasciculations. Esophagitis The inflammation of the mucosal lining of the esophagus. Gastric Motility The spontaneous peristaltic movements of the stomach that move the stomach contents through the pyloric sphincter into the duodenum. Gastroesophageal Reflux Often referred to as heartburn; the result of backflow of stomach contents due to the relaxation of the smooth muscle of the lower esophageal sphincter. Hypovolemia A reduction from normal in blood volume. Physiologic Anemia of Pregnancy The normal increase in plasma volume, up to 50%, which exceeds the increase in red blood cell volume resulting in anemia. Plasma Cholinesterase An enzyme in the plasma that is responsible for the metabolic breakdown of acetylcholine to choline and acetate. Pruritus An unpleasant skin sensation or itching that creates the desire to scratch or rub. Retained Placenta Failure to completely deliver the placenta within 30 minutes of delivery of the infant. Occurs in approximately 3% of vaginal deliveries and can be a cause of postpartum hemorrhage.5 Sepsis A potentially life-threatening condition caused by the body’s response to an infection. Thromboembolism Obstruction of a blood vessel by a blood clot that has become dislodged from another site in the circulation. Almost every system in the body is affected in some way during pregnancy, either from hormonal changes or from the increasing size of the uterus. The perianesthesia nurse must be familiar with the physiologic changes of pregnancy because they will impact postoperative nursing care (see Box 51.1). Surgery may be required during any stage of pregnancy. The American College of Obstetricians and Gynecologists (ACOG) and American Society of Anesthesiologists (ASA) guidelines on nonobstetric surgery during pregnancy recommend that elective surgery should not be performed during pregnancy and that necessary surgery not be denied due to trimester considerations.3,4 If surgery is deemed necessary, the second trimester is preferred because of its association with the lowest risk for spontaneous abortion and preterm labor.1,3 Some of the indications for pregnancy-related surgery include cervical incompetence, the presence of ovarian cysts, and conditions amendable to fetal surgery.2 Indications for nonpregnancy-related surgery include the presence of acute abdominal disease (most commonly appendicitis and cholecystitis), malignancy, and trauma.1–4 When caring for pregnant women undergoing nonobstetric surgery, the anesthesia provider will need to alter standard anesthetic practices with special considerations to the pregnancy-induced physiologic changes as well as the gestational age of the fetus. The supine position causes a reduction in uterine blood flow in the pregnant patient; therefore, the semi-Fowler position is used when possible. To prevent aortocaval compression, the patient is placed in the left lateral decubitus position and the right hip is elevated with a pillow, or the uterus is displaced to the left with devices on the operating table.1 (Fig. 51.1) Preoperative fasting guidelines must be observed for scheduled surgeries. The ASA recommends that patients abstain from solid food for at least 6 to 8 hours for fried or fatty food and 2 hours for clear liquids prior to surgery.6,7 Because the pregnant patient is at increased risk for aspiration pneumonitis, many anesthesia providers will administer a variety of pharmacologic agents preoperatively. A nonparticulate antacid, sodium bicitrate, 30 mL is given to increase the gastric pH; a histamine-2 receptor blocker such as famotidine 20 mg or ranitidine 50 mg intravenously (IV), which reduces gastric acid secretion, preferably given at least 30 minutes before the procedure; and gastro-kinetic agent such as metoclopramide 10 gm IV, which increases both gastric motility and lower esophageal tone.6,7 The pregnant patient is at increased risk for postoperative nausea and vomiting (PONV) and should receive PONV prophylaxis with dexamethasone, which is given just after induction, and ondansetron, which is given on emergence. Dexamethasone blocks the synthesis of prostaglandins which sensitizes nerves to other commonly involved neurotransmitters in emesis control.8,9 It may act in the CNS by antagonizing 5-HT3 receptors or corticosteroid receptors in the nucleus tractus solitarius.8,9 Ondansetron is a serotonin (5-hydroxytryptamine subtype 3 [5-HT3]) receptor antagonist; it binds to 5-HT3 receptors in the chemoreceptor trigger zone and at vagal afferents in the gastrointestinal tract.8,9 See Chapter 29 for further information on PONV. Retrospective studies from the 1970s demonstrated an increased incidence of cleft lip and palate in infants of mothers who were taking the benzodiazepine diazepam during pregnancy.10,11 However, more recent studies have failed to demonstrate this association or a definite risk of other anomalies, although a small increase in risk could not be excluded.1,3,12 Benzodiazepines such as midazolam are commonly used in the preoperative setting and have never been associated with congenital malformations.1,3,12 During the consent process for general anesthesia, the anesthesia provider should discuss the medications that will be used and their safety during pregnancy. Many pregnant patients prefer to avoid unnecessary sedatives. The incidence of difficult airway in pregnant women has been reported in 0.45% to 5.7% intubations.13–20 Difficult airway intubations in the general surgical population are similar at 5.8%, but the outcome of a difficult intubation can be consequential in the obstetric population.20 The definition of difficult airway includes the following: difficulty in providing mask ventilation, insertion of a supraglottic airway (laryngeal mask airway or iGel), or tracheal intubation.13–15 The anesthesia provider will perform a thorough evaluation of the pregnant patient’s airway prior to induction.13–19 The airway examination can include Mallampati class designation (class I: visualization of soft palate, fauces, uvula, pillars; class II: visualization of soft palate, fauces, uvula; class III: visualization of the soft palate, base of uvula; class IV: soft palate is not visualized, hard palate only; thyromental distance, atlanto-occipital extension, and mandibular protrusion [class A: the lower incisors can protrude anterior to the upper incisors; class B: the lower incisors can be brought edge to edge with the upper incisors; class C: the lower incisors cannot be brought edge to edge with the upper incisors]).18–22 During direct laryngoscopy, a class A appears to be a good indicator for a favorable glottic view, while a class C is associated with a poor glottis view.13–14,22 The outcome of the patient’s airway assessment in conjunction with the available devices will vary among institutions, but all the necessary airway equipment should be gathered in advance when preparing for intubation such as oral airways, blades and handles, Eshmann stylet, video laryngoscope, and/or fiberoptic scope.13–15,23 Proper patient positioning is critical in order to obtain an optimal view of the vocal cords during larygoscopy.13,14,24 The sniffing position is considered to be the ideal position for aiding in the view of the glottic opening by aligning the oral, pharyngeal, and laryngeal axes.13,14,24 Obese patients must be ramped due to an increase in their anteroposterior chest diameter, making neck flexion unachievable in the supine position.13,14,24 Ramping refers to the placement of blankets, pillows, or a commercially made device that raises the shoulders and upper torso so that the external auditory meatus and the sternoclavicular joint are in horizontal alignment.13,14,24 Once the patient is properly positioned on the operating bed, preoxygenation or denitrogenation with 100% oxygen is initiated.13,14,24 The functional residual capacity (FRC) is decreased during pregnancy and is the primary reservoir for oxygen during periods of apnea.13,14,24 Therefore, effective denitrogenation of the FRC is critical to delay the onset of desaturation and hypoxemia during intubation.13,14,24 The pregnant patient is at risk for aspiration and her airway is secured with RSI technique (see Chapter 30).13–15 One of the following IV sedative- hypnotic medications—propofol, etomidate, or ketamine—is used as an induction agent followed by a neuromuscular medication, succinylcholine. A defasciculating dose of a nondepolarizing muscle relaxant can be given prior to the administration of succinylcholine to decrease or attenuate the fasciculations, which can increase intragastric pressure. Administering a defasciculating dose of a nonpolarizing muscle relaxant is provider preference. There are many anesthesia providers who prefer to use high-dose rocuronium, 1.2 mg/kg, for RSI. Cricoid pressure (Sellick maneuver) is applied with an assistant’s thumb and index fingers just prior to administering the induction agent and maintained until the endotracheal tube (ETT) placement is confirmed.13–15 The ETT should be a small tube, usually 6.0 to 6.5 mm in diameter because of increased mucosal engorgement in the oropharynx.13–15 Nasotracheal intubation is not used because of the high risk of tissue trauma.10,11 Volatile inhalational agents such as sevoflurane, isoflurane, and desflurane have been used safely during pregnancy.1,4,12 A 30% to 40% decrease in the minimum alveolar concentration (MAC) of volatile anesthetic agents has been observed during pregnancy; this correlates with higher serum progesterone levels.4,12 When general anesthesia is performed for urgent to emergent cesarean deliveries, there is a relatively high risk for intraoperative awareness or 1 in 670 general anesthetics.4 Similar circumstances are commonly encountered during nonobstetric surgery during pregnancy.4 A processed electroencephalogram (e.g., bispectral index), if available, is recommended because it can be used to guide the depth of anesthesia and decrease the risk of intraoperative awareness.25 There is a concern about nitrous oxide use during pregnancy as it has been shown to be a weak teratogen in animal models because of its effect of inhibiting synthetase and impairing DNA production, particularly in the first trimester when organogenesis is occuring.4 To date, there has been no human study that has shown any increase in the rate of congenital malformations with nitrous oxide use and this includes a study of over 2000 women who underwent surgery in the first trimester, most with the use of nitrous oxide.2 Although this evidence is reassuring, it is the practice of many anesthesia providers to avoid nitrous oxide during the first trimester of pregnancy. The depth of neuromuscular blockade is frequently assessed using a peripheral nerve train-of-four (TOF) monitor. There are two types of peripheral nerve monitors that are commonly used: the traditional peripheral nerve monitor, which is considered a qualitative monitor, or the accelerometer, which is a quantitative monitor.26 If continued neuromuscular blockade is required and succinylcholine was administered for intubation, upon return of neuromuscular function as demonstrated by TOF of 4/4, a small dose of an intermediate-acting nondepolarizing muscle relaxant is given such as rocuronium or vecuronium.26 Core body temperature is tightly regulated and normally is maintained within a few tenths of degrees Celsius.27–29 Thermoregulation is impaired during either general or neuraxial anesthesia. Consequently, unwarmed anesthetized patients can quickly become hypothermic by 1° C to 2° C.27–29 Normothermia should be maintained during surgery, but temperature disturbances, hypothermia, or hyperthermia can only be detected by temperature monitoring. There are a variety of consequences of hypothermia. Most cellular functions are temperature dependent, and hypothermia provokes systemic responses such as problems with bleeding or impairment of the clotting cascade, prolongation of drug effects, and impairment of host defenses against surgical wound contamination.27,28 Most institutions can initiate a variety of active warming measures such as forced-air warming devices, fluid warmers, and/or respiratory gas warmers. Postoperative temperature derangements are common, and the patient’s temperature should be measured during the initial assessment upon arrival in the postanesthesia care unit (PACU).28,29 If core temperature is low, warming measures with warm blankets or a forced-air warming blanket must be initiated. At the end of the surgical procedure, the residual effects of the nondepolarizing muscle relaxant are reversed with neostigmine and glycopyrrolate and the inhalational anesthetic agent is discontinued. If using an accelerometer to monitor neuromuscular function, a TOF greater than 90% is recommended for full return of neromuscular function.26 When the patient is awake, responsive, neuromuscular function has returned to baseline, and she is able to ventilate and maintain an adequate minute volume without assistance, extubation is performed.26 According to the Society for Obstetric Anesthesia and Perinatology (SOAP) statement on sugammadex during pregnancy and lactation, there is insufficient evidence on the safety of sugammadex during early gestation.30 Due to the interaction between sugammadex and progesterone components of hormonal contraceptives, there is concern for adverse interactions between sugammadex and endogenous progesterone in early pregnancy.30–32 Since progesterone is critical for the maintenance of pregnancy, SOAP advises against the use of sugammadex in this patient population until the clinical implications of this drug are known.30 From a maternal perspective, for women who are at term or near term and require general anesthesia for CD, sugammadex appears to be safe and effective.30–32 Inhalation agents can produce uterine relaxation; therefore, postoperative monitoring should include a frequent assessment of fetal heart tones, signs of postoperative bleeding, maternal vital signs, and passive warming techniques, as well as maternal psychological support.4,12 Studies have not shown one anesthetic technique to be better than another in the gravid patient. As with nonpregnant patients, the choice of technique is determined by the following: The care of the pregnant patient after surgery should be the same as for any patient who undergoes a surgical procedure or for one who recovers from a general anesthetic. In addition to routine postoperative nursing care, there are special considerations for all pregnant patients who undergo a nonobstetric surgical procedure.4,12 Nursing actions to alleviate aortocaval compression include the following: placing the mother in the side-lying position by tilting the pelvis, flexing the legs to decrease the lumbar lordosis, or crossing one leg over the other to tilt the pelvis, all of which may reduce the aortocaval compression (Fig. 51.1).33 A significant increase in left ventricular ejection fraction, end-diastolic volume, and stroke volume should result.6,7,33 Hypotension unresponsive to position changes may need to be treated with the administration of an IV fluid bolus and/or a vasopressor bolus with either phenylephrine or ephedrine.33 In the United States, one of the leading causes of maternal mortality is venous thromboembolism, making up 9.3% of all maternal deaths.34 Pregnant women have a fourfold to fivefold increased risk of thromboembolic events compared with nonpregnant women and approximately 80% of these events in pregnancy are venous in origin.34 Therefore, it is vital that throughout the perioperative period and until the patient is fully ambulatory, antiembolism stockings or lower extremity sequential compression devices be maintained.35 The mother’s concern for the unborn child is paramount. Constant reassurance is mandatory. If possible, allow the mother to listen to the fetal heartbeat frequently during the recovery phase. Explain all procedures and why they are necessary before they are followed. If the PACU allows visitors, involvement of the family should also be considered.36 In the PACU, it is essential to focus on the mother’s postoperative psychological condition. The fetal heart rate must be monitored every 15 minutes if the fetus has reached viability (Table 51.1). If available, an indirect fetal monitoring system should be used for constant assessment of fetal stability. If the fetus is considered previable, it is generally sufficient to ascertain the fetal heart rate by Doppler before and after the procedure.1,37 Modified from Livingston, EG. Intrapartum fetal assessment and therapy. In: Chestnut, DH, Wong, CA, Tsen, LC, Nagan Kee WD, Beilin Y, Mhyre T, Bateman BT, eds. Chestnut’s Obstetric Anesthesia: Principles and Practice. 6th ed. Elsevier, Inc. 2020:155–170.
51: Care of the Pregnant Patient
Abstract
Keywords
Physiologic changes of pregnancy
Nonobstetric surgery during pregnancy
Positioning
Gastrointestinal Considerations
General Anesthesia
Sedative Premedication
Induction
Maintenance
Maintenance of Normothermia
Emergence
Perianesthesia care of the mother and the fetus
Positioning
Psychological and Emotional Support
Fetal Monitoring
Description
Rate (Beats/Min)
Normal fetal heart rate
110–160
Tachycardia
> 160
Bradycardia
< 110
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