Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_540_Библиотеки_им_академика_М_И_Перельмана

A pregnant woman should never be denied medically necessary surgery or have that sur­gery delayed regardless of trimester because this can adversely affect the pregnant woman and her fetus. (ACOG 2019 [1])

(oxytocic effects),

• avoidance of maternal awareness during gen-

eral anesthesia,

• use of regional anesthesia, if possible.

No currently used anesthetic agents have

The drugs crossing the placenta may be catego­rized into three types. In type 1 (e.g., thiopental), the complete transfer occurs with equilibrating maternal and fetal blood concentrations. In type 2 (e.g., ketamine), the drug reaches a higher concen­tration in fetal blood than maternal blood. Only a minimal amount reaches the fetal blood in type 3 (e.g., succinylcholine).

been conrmed [13]. Rapid neuromuscular blockade reversal is conrmed in myasthenia gravis patients during CS [14].

toring is mandatory [19, 20]. Following electrocar­diography, noninvasive blood pressure measurement, pulse oximetry, and fetal heart rate monitoring (FHR) devices are applied. Insufation of oxygen at a ow rate of 6L/min is maintained throughout the procedure. The patients are placed in a left lateral to a prone position. Fetal shielding is accomplished with a lead apron placed between the radiation source and the patient. Although there is no proof of human teratogenicity for anesthetic drugs, inhaled or local, all agents administered dur­ing pregnancy must be used with caution and vigi­lance. Currently, the best options are propofol, midazolam, and fentanyl. Propofol is preferred as a short-acting agent because it can be titrated easily and has a good recovery, with a low incidence of nausea and vomiting. Alternatively, midazolam can be used because of its specic amnesic and anxio­lytic properties. The analgesic component of this sedation regimen is opioids. All drugs are given in incremental doses to prevent hemodynamic and respiratory changes in the mother and fetus during the procedure. The most commonly conscious seda­tion is achieved and maintained with intravenous midazolam 3–5 mg and duodenal hypomotility induced by hyoscine-N-butylbromide 20mg [21].

gastric emptying and decreased lower esopha-

geal sphincter tone in combination with

increased intra-abdominal pressure,

tion in pregnancy, because of lower serum

lead to a falsely non-reassuring tracing and

Additionally, vascular engorgement of the respiratory tract during pregnancy may lead to tracheal intubation difculties. Edema in the air­ways leads to friable tissues, increased potential for bleeding, and the necessity to use smaller­sized endotracheal tubes in the parturient [30]. Because decreased lower esophageal sphincter pressure and delayed gastric emptying in preg­nancy can cause an increased risk of aspiration, cricoid pressure prevents aspiration during intu­bation [31]. Therefore, rapid-sequence intubation is preferred for the parturient facing an emergent abdominal operation with a full stomach [30]. Also, the underlying cause of acute abdomen,

intraoperative strategy, and possible intraopera­tive complications mandates general anesthesia.

General anesthesia and positive-pressure venti-

The literature on pregnant trauma victims’ obstet­ric, anesthetic, and surgical management is lim­ited [38]. Pregnant trauma victims present a unique spectrum of challenges to the trauma healthcare team. The diagnosis may be unknown at exploration, as may be the nature and extent of the further procedures. Pregnancy may not always be known to the healthcare team (at the scene of transportation accidents, emergency room, or operating room), complicating the situation.

Women in late pregnancy have difcult airways. Mallampati class 4 airway (with only the hard palate visible and with no view of the soft palate or uvula) increased by 34% between 12 and 38 weeks [39]. The additional fact that these patients have sustained trauma and will likely be in cervical collars compounds is an already dif­cult situation [40]. If there is uncertainty about the integrity of the cervical spine, direct laryn­goscopy should be avoided, and beroptic (awake beroptic) intubation of the trachea, if feasible (time constraints or equipment availability), should be considered [41]. If direct laryngoscopy is deemed necessary, an “inline stabilization” of the head and neck by an assistant to prevent extension and rotation of the cervical spine is indicated. If awake, beroptic tracheal intubation is chosen. Analgesic and sedative drug titration maintains continual meaningful verbal commu­nication between the anesthesiologist and the patient.

Respiratory depression and aspiration of stom­ach contents with local anesthesia are less likely if the patient remains awake and alert. Also, a ratio­nal, alert mother minimizes the risk of neonatal depression. In patients in anesthesia, nasogastric decompression after intubation reduces the risk of aspiration. Midazolam is the recommended ben­zodiazepine. However, it is highly unionized and lipophilic, and the feto- maternal ratio is 0.76 at 15–20 min after maternal administration. However, unlike other benzodiazepines, the ratio falls rapidly. No adverse fetal effects have been reported [42]. Trauma victims with a GCS ≤8

usually require intubation and mechanical venti­lation for intracranial pressure and airway control. However, trauma victims with “good” GCS can “talk and deteriorate/die” following a traumatic head injury, particularly an injury associated with loss of consciousness. Delayed deterioration occurs within 48h from the initial insult.

The succinylcholine-induced ICP increase has been a concern in the past. With an urgent need to secure an airway in a head-injured preg­nant trauma victim, succinylcholine is an appro­priate and safe drug. All the intravenous anesthetic agents (except ketamine) cause some degree of vasoconstriction and therefore decrease cerebral blood ow. The inhaled agents have some cerebral vasodilatory effect; however, their administration is usually consistent with accept­able ICP levels [43].

acute fetal compromise. If the patient has a normal airway and, other than the cervical col­lar, there are no reasons for anticipating dif­culties with intubation, general anesthesia with inline neck stabilization during intubation is the most appropriate [44].

laparotomy [50]. Partly it depends on the quan­tity of blood loss. Hypovolemic shock may lead to the translocation of gram-negative bacteria from the ischemic bowel to the bloodstream, complicating the presentation with endotox­emia and septic shock [51]. Hemorrhagic shock increases the incidence of wound infections. Most survived mothers had a mean blood loss of >2000mL [52–54]. Blood loss depends on the trimester of UR and uterotonics or prosta­glandins for labor induction. These medications can decrease the amount of blood loss [55].

ECMO therapy may be benecial during preg-

See Sect. 25.3.6.6. A total of 20 ECMO cases of amniotic uid embolism from 1986 to 2019 were published [67]. Extracorporeal therapies consisted of venoarterial ECMO (11 cases), venovenous ECMO (3 cases), and cardiopulmonary bypass (3 cases, including 2 older cases). Extracorporeal therapies were started after delivery and were con­tinued for a median of 48h. The length of ICU stay ranged from 7 to 59days. Maternal and neonatal survival was 85%. Maternal hemorrhage compli­cated 69% of cases, with a few patients requiring more than 10 red blood cell transfusions [67].

Interests of both the mother and the fetus must be considered in therapy during pregnancy. Usually, these interests do not conict because what is good for the mother is generally good for the fetus. Sometimes maternal therapy must be mod­ied to substitute alternative but safer therapy because of the concerns about drug teratogenicity (e.g., replacing a H2 receptor antagonist for miso­prostol, an abortifacient that is contraindicated during pregnancy) [70, 71]. Rarely, the maternal and fetal interests are opposed, as in chemother­apy for maternal cancer. This therapy is poten­tially life-saving to the mother but life-threatening to the fetus [72]. These conicts raise signicant medical, legal, and ethical issues.

There are many categories of drugs that could have deleterious effects on a fetus, and detailed elaboration is out of the scope of this book. There are three main categories of medications used in these patients: (1) anesthetic medications (see Sect. 2.1.1), (2) prophylactic, and (3) therapeutic. All teratogenic drugs generally determine a spe­cic pattern or single malformation during a sensi­tive gestation period with a dose-dependent effect.

• category A: studies in pregnant women do not demonstrate any risks to the mother or fetus,

• category B: while animal studies show no risk, human studies are inadequate,or animal toxic­ity has been noted, but the studies on humans show no risk.

Class B antibiotics should be administered when the acute abdomen is highly suspected or found (at least 30–60 min before skin incision) in all patients (administered to 94% of patients in the literature) [73].