Animal studies: show adverse effect
Animal studies: adverse effects (teratogenic, embryocidal). Only give if benefits outweigh risks
Animal studies: teratogenicity in animals. Contraindicated in pregnancy. Example: thalidomide
Maternal hypotension from any cause can jeopardize uteroplacental perfusion and cause fetal asphyxia. It is initially treated with fluids (crystalloid, colloid, blood products) when appropriate; phenylephrine and ephedrine are the two most common vasopressors used in pregnancy. Randomized controlled trials comparing ephedrine with phenylephrine for the treatment of maternal hypotension have shown there is no difference between them in efficacy, nor incidence of true fetal acidosis, although maternal bradycardia was more common with phenylephrine.[14] One should attempt to keep maternal blood pressure within 20% of the preoperative baseline.
Maternal hypertension in the PACU is usually from inadequately treated pain, but may also be from sympathetic overactivity, which could compromise uteroplacental perfusion. Most antihypertensive medications can be used safely in the PACU while monitoring the fetal heart rate, with the exception of esmolol and angiotensin-converting enzyme (ACE) inhibitors. Esmolol may cause a prolonged fetal heart rate bradycardia and a reduction in fetal PaO2;[15] ACE inhibitors are teratogenic (Table 45.2).
| Drug category | Drug | FDA risk category |
|---|---|---|
| IV opioids | Fentanyl Morphine Hydromorphone Meperidine | C C C C |
| Benzodiazepines | Midazolam Diazepam Lorazepam | D D D |
| Anti-emetics | Ondansetron Droperidol Metoclopramide H2 blockers Promethazine Hydroxyzine | B C B B C C |
| Anti hypertensives | Labetalol Nifedipine Alpha methyldopa ACE inhibitors Angiotensin receptor blockers (ARBs) Magnesium | C C B D D A |
| Vasopressors | Ephedrine Phenylephrine Epinephrine | C C C |
| Other pain relievers | NSAIDs Tramadol Aspirin Acetaminophen | D C D (3rd trimester) B |
| Antithrombotics | Heparin Enoxaparin | C B |
| Glucocorticoids | Dexamethasone | C |
Opioid analgesics commonly used in the PACU lack teratogenic effects in clinical doses; however, they do decrease FHR variability.[7] Most are considered Category C drugs when used during pregnancy (Table 45.2). Occasionally, anxiolytics are needed in the PACU. Benzodiazepines are Category D because of an association with first trimester use and an increased incidence of cleft lip and palate, neural tube defects, intestinal atresia, and limb defects.[16] Although the consensus among teratologists is that benzodiazepines are not proven human teratogens, the package insert for these drugs warns of these risks. Of bigger concern is over-sedating the postoperative pregnant patient. Adequate supervision and monitoring in the PACU are essential to minimize the incidence of airway obstruction, apnea, and aspiration which can result in maternal death.[17]
Aspirin causes permanent inhibition of prostaglandin synthetase in platelets and may increase the risk of bleeding after certain surgical procedures. Acetaminophen does not, and both are considered safe for use during pregnancy. Although non-steroidal anti-inflammatory drugs (NSAIDs) do not cause teratogenicity, they can cause constriction of the fetal ductus arteriosus if used after 32 weeks’ gestation.[18]
Postoperative nausea and vomiting in the pregnant patient can lead to dehydration, which may precipitate the development of preterm labor. Most agents used to treat nausea and vomiting in the PACU are Category B or C in pregnancy (Table 45.2). These include H2-receptor antagonists, metoclopramide, promethazine, droperidol, and ondansetron.[18] Glucocorticoids are used to hasten fetal lung maturity in threatened preterm deliveries, so one can infer that a dose of dexamethasone in the PACU to alleviate PONV would not be harmful.
Since pregnancy is a hypercoagulable state, postoperative thromboembolism prophylaxis should be continued in the postoperative period. Early mobilization for a pregnant patient in the PACU may not be feasible during continuous fetal heart rate monitoring, but one should get the parturient out of bed as soon as possible if the PACU stay will be lengthy. Other methods of prophylaxis include continuing the use of intraoperatively placed pneumatic compression devices or anti-embolic compression stockings, and continuing any preoperative anticoagulation measures when appropriate. Low molecular weight heparin and unfractionated heparin are safe in pregnancy and may be given in the PACU under the direction of the surgeon or obstetrician.[18] If the parturient has received regional anesthesia, one should follow the guidelines recommended by the American Society of Regional Anesthesiologists when beginning postoperative anticoagulation.[19]
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