B Cesarean section
A cesarean section (C-section) is the surgical removal of a fetus through an abdominal and uterine incision. A low transverse incision is the most common; in an emergency, a rapid vertical midline incision may be used. Indications for a C-section are failure of labor to progress, previous C-section, fetal distress, malpresentation of the fetus or umbilical cord, placenta previa, and genital herpes or other local infections.
2. Preoperative assessment
a) A focused assessment should include obstetric and anesthetic history, maternal health, airway, allergies, and baseline vital signs. In emergency cases, the time for assessment will be brief. Special attention should be paid to airway assessment because failed intubation is a major cause of maternal morbidity and mortality.
b) Key points regarding physiological changes in pregnancy
(1) Cardiac output increases mostly because of the increase in stroke volume but also because of increase in heart rate.
(2) The greatest demand on the heart is immediately after delivery when cardiac output increases 180%.
(3) Blood volume is markedly increased and prepares the parturient for the blood loss associated with delivery.
(4) Plasma volume is increased to a greater extent than red blood cell volume, resulting in a dilutional anemia.
(5) Minute ventilation increases 45%, and this change is mostly caused by the large increase in tidal volume.
(7) Pregnant women have an increased sensitivity to local anesthetics and a decreased minimum alveolar concentration (MAC) for all general anesthetics.
(9) Intragastric pressure is increased in the last trimester, which, in combination with increased acid volume, often results in heartburn.
3. Patient preparation
a) A nonparticulate antacid (e.g., sodium citrate, 30 mL) and metoclopramide 10 mg IV are routinely administered at most institutions regardless of the anesthetic technique chosen. Sedation is best avoided. Benzodiazepines have been implicated as possible teratogens, and it is best to avoid maternal amnesia during childbirth.
b) Laboratory tests should include a type and screen, complete blood count (CBC), electrolytes, blood urea nitrogen, creatinine, glucose, prothrombin time, and partial thromboplastin time. In emergency C-sections, there may not be time to complete these tests.
c) The parturient should have at least one large-bore intravenous (IV) lines in place before induction of anesthesia.
4. Room preparation
b) Positioning: Supine with left lateral uterine displacement. This is accomplished by placing a wedge under the right hip. Failure to use left lateral uterine displacement can result in aortocaval compression.
