1. Distinguish between vasoconstrictive (resistance) hypertension and flow-type hypertension.

2. Calculate pulse pressure and use in determining type of hypertension.

3. Select the appropriate antihypertensive medication, based on action and indication.

4. Recognize normal physiologic changes that occur in pregnancy.

5. Participate in the management of pregnant trauma patients.

Hypertensive Emergencies During Pregnancy
Michael R. Foley, MD, Clinical Professor, Department of Obstetrics and Gynecology, University of Arizona College of Medicine at the Arizona Health Sciences Center, Tucson; Medical Director for Academic Affairs, Scottsdale Healthcare, Scottsdale, AZ

General considerations: definition of hypertensive emergency—diastolic blood pressure (BP) >110 mm Hg; mean arterial pressure (MAP) used infrequently; data support greater morbidity for mother and fetus when systolic BP >160 mm Hg than when diastolic >110 mm Hg; associated complications—hypertensive encephalopathy; acute heart failure; myocardial infarction (MI)

Causes of acute hypertension: BP equals flow times resistance; BP becomes elevated because of increased resistance (vasoconstriction) or increased flow or both; reasons for increased flow—increased crystalloids; high-dose steroids, renal failure; increased cardiac output (contractility); reasons for increased resistance—drugs (eg, cocaine); α-adrenergic stimulation (eg, pain); increased intracranial pressure (ICP); hyperthyroidism; increased renin; preeclampsia; appropriate treatments (resistance vs flow hypertension)—vasodilators (eg, hydralazine) indicated for patient with resistance hypertension; diuretics (ie, furosemide) indicated for flow hypertension to decrease intravascular volume; administered with β-blocker

“Gestalt” of BP: diastolic component of BP represents degree of vasoconstriction (resistance); abnormal value usually indicates resistance-type hypertension; pulse pressure—difference between systolic and diastolic BP; pulse pressure equivalent to stroke volume in pregnant population (particularly in patients with preeclampsia); normal pulse pressure 40 to 50 mm Hg; pulse pressure >50 mm Hg, together with increased diastolic BP, indicates flow hypertension; increased flow leads to hypervolemia; interventions for hypervolemia—decrease sodium-containing fluids; reduce intravenous (IV) fluids; consider loop diuretic and vasodilator; increased resistance (vasoconstriction)— correct oxygenation and CO2 ; control ICP; side point—administer α-blocker before β-blocker to prevent stroke in patient with pheochromocytoma

Clinical utility of pulse pressure: narrowing pulse pressure clinically useful clue to possible occult bleeding (eg, placental abruption); useful in assessing appropriate fluid preload before spinal or epidural anesthesia; with wide pulse pressure, less fluid preload needed; with narrow pulse pressure, more fluid preload needed

Medications for hypertension: avoid polypharmacy and overlapping mechanisms of action; hydralazine—indicated for restrictive hypertension; hydralazine and labetalol have long half-lives; should not be administered as continuous drip; “drip drugs” (eg, nitroglycerin, nitroprusside, esmolol [Brevibloc]) have short half-lives, allowing for immediate reversal when discontinued; sodium nitroprusside—indicated for severe refractory acute restrictive hypertension; short half-life; increase dosage every 5 min until appropriate response; cyanide toxicity associated with nitroprusside; prevented by concomitant administration of sodium thiosulfate; consult with anesthesiologist in assisting in control of patient’s BP before going to delivery room; nifedipine—speaker considers first-line agent for preterm labor; calcium channel blocker; indicated for increased resistance; propranolol— β-blocker; rarely used because of long half-life; esmolol—short-acting β-blocker; could be administered concomitantly with diuretic for patient with flow hypertension

General principles of treatment: evaluate disease process by taking thorough history and performing physical examination to determine what is causing symptom of hypertension (rather than considering hypertension a disease); consider ramifications of decreasing BP too quickly; restore and carefully assess volume status; decreased volume with increasing systemic vascular resistance causes vasoconstriction; increased volume can lead to pulmonary and cerebral edema

Trauma in Pregnancy
Franklyn H. Geary Jr, MD, Associate Professor, Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, and Residency Program Director, Morehouse School of Medicine, Atlanta, GA

Physiologic changes in pregnancy: genitourinary tract—uterine enlargement (compartmentalizes peritoneal cavity); repositioning of bladder; dilatation of ureters; uterus rotates to right side; hydronephrosis may occur; progesterone causes relaxation of smooth muscle; gastrointestinal tract—decreased motility; delayed gastric emptying; bowel in upper abdomen; respiratory system—increased tidal volume; increased minute ventilation; decrease in functional residual capacity; respiratory alkalosis; compensatory decrease in plasma bicarbonate (plasma pH remains unchanged); cardiovascular and hematologic changes—increased cardiac output (50%); increased blood volume (more plasma volume than red blood cell mass, “physiologic anemia”); tachycardia; decreased systemic vascular resistance; decreased oncotic pressure; leukocytosis; chest x-ray findings—elevation of diaphragm (4 cm); increased anteroposterior chest diameter; cephalization of pulmonary vasculature; widening of mediastinum; heart appears enlarged

General considerations: trauma one of leading causes of morbidity and mortality in women worldwide; ≈1 million deaths annually; one of leading causes of morbidity and mortality during pregnancy; ≈1 in 12 women experiences physical trauma; maternal mortality leading cause of death in reproductive-age women; motor vehicle accidents (MVAs) account for approximately two-thirds of all cases; abruptio placentae occurs in ≈40% to 50% of pregnant women experiencing trauma; incidence ≈1% to 5% when trauma non–life-threatening

Additional concerns: effects of drugs on uterine blood flow; potential mutagenic and teratogenic effects of diagnostic radiation and medications; effect of surgery on pregnancy; gestational age of fetus (in most tertiary care centers, fetus considered viable at 24 wk gestation); multidisciplinary approach, but obstetrician often responsible for coordinating care; obstetrician acts as advocate for mother and fetus; challenges—short neck, difficult airway

Motor vehicle accident: direct trauma leads to rapid deceleration; relatively inelastic placenta separates due to deformation of elastic myometrium; management—evaluation including Rh status (most blood banks can calculate how much RhoGAM necessary in patients with massive blood loss); monitor Rh status for 2 to 6 hr if patient asymptomatic, 12 to 24 hr if symptomatic; assess patient for cervical changes and evidence of preterm labor; consider abruptio placentae

Abruptio placentae: premature separation of normally implanted placenta; commonly associated with preterm labor and delivery; accounts for 15% to 25% of all cases of perinatal mortality; pathophysiology—bleeding into decidua basalis; independent of placental location; characterized by painful vaginal bleeding, hypertonic uterine contractions, and fetal distress; management—depends on gestational age; ultrasonography (US) to rule out abruption; blood can resemble placental tissue (depends on gestational age); consider expectant management or tocolytic therapy if patient preterm or mild abruption occurs; delivery indicated with moderate to severe abruption (ie, profuse maternal hemorrhage, fetal distress); amniotomy; appropriate use of cesarean delivery; appropriate use of blood and blood components

Uterine rupture: infrequent, but life-threatening; related to substantial force; serosal hemorrhage or abrasions; avulsion of uterine vasculature with hemorrhage; complete disruption of uterine wall with fetal extrusion into abdominal cavity; ≈75% of cases involve fundus; uterine tenderness; nonreassuring fetal heart pattern; may or may not have changes in maternal vital signs; one-quarter to one-third blood loss may occur before evidence of hemodynamic instability seen; motor vehicle safety restraint (seat belt) —instruction in proper use of safety restraints should be incorporated into prenatal discussion; full restraint (shoulder belt, as well as lap belt) should be worn

Domestic violence: every 9 sec in United States, woman physically abused by husband (incidence possibly more frequent if partner not husband); ≈4 million Americans (7%) who are married or cohabitating physically abused; 20 million (37%) verbally or emotionally abused by partner; ≈95% of assaults on spouses or ex-spouses committed by men against women; 25% to 45% of battered women have been battered in pregnancy, increasing incidence of miscarriage, preterm labor, and low birth weight; 50% of women murdered in United States killed by intimate male partner; 90% of women physically abused by partner did not discuss incidence with physician (“if we don’t ask, they don’t usually volunteer that information”); 57% did not discuss abuse with anyone

Blunt trauma: management depends on gestational age, extent and severity of maternal injury, and mechanism of injury; viability —at <13 wk gestation, fetus protected by bony pelvis; at >13 wk, uterus becomes abdominal organ and fetus subjected to other types of trauma; aortic cable compression and decreasing venous return leads to decreased cardiac output; position of patient should be left lateral tilt, not supine; direct fetal injury—occurs in <1% of pregnancies related to trauma; reported with minor injuries, but occur mostly with major trauma; pelvic fracture—significant hypovolemic shock associated with retroperitoneal bleeding caused by pelvic fracture; possible injury to urethra, bladder, and ureter; obtain x-ray of pelvis to determine extent of injury; vaginal delivery not always contraindicated in patient with pelvic fracture

Penetrating trauma: gunshot wounds, stab wounds; increased risk for fetal loss from direct injury or injury to placenta or blood vessels; hysterectomy may be necessary; stab wound—consider possible bowel injury (bowel may be protected by enlarged uterus); gunshot wound—consider extent, severity, firing distance, and size and velocity of bullet; consult with trauma surgeons; management—secure and maintain airway; insert large-bore IV lines; maintain oxygen saturation; administer crystalloid at 3:1 ratio; vasopressor if BP low (ephedrine does not decrease uterine blood flow, but can raise BP); undress patient and perform thorough examination; culdocentesis option for assessing abdomen and pelvis; radiologic studies (eg, computed tomography [CT]); peritoneal lavage; exploratory laparotomy; tetanus toxoid as indicated (especially if patient does not remember last injection); check patient’s Rh status; intraoperative fetal heart rate monitoring (sterile Doppler); postoperative deep venous thrombosis (DVT) prophylaxis (eg, pneumatic compression hose, subcutaneous heparin; cesarean delivery—depends on extent of injury to uterus; cesarean hysterectomy may be necessary to allow for better exploration of abdomen; consider gestational age (maternal condition generally takes priority)

Fetal assessment: electronic fetal heart rate monitoring and uterine activity monitoring; no large prospective studies looking at monitoring; use clinical judgment; US or biophysical profile (BPP) may reveal extent of fetal injury; amniotic fluid index if scan reveals fluid surrounding empty uterus; Kleihauer-Betke testing—not shown to predict adverse immediate sequelae due to hemorrhage; RhoGAM if appropriate

Head trauma: sudden deceleration or acceleration forces sheer off small blood vessels, leading to vascular injury; brainstem houses reticular activating system (RAS); severe neck injury can lead to respiratory arrest; concussion characterized by lack of anatomic defect; contusion characterized by anatomic problem (eg, intracerebral hemorrhage or subdural hematoma); skull fracture—usually not associated with major injury; manage as indicated (eg, suture wound); monitor mother; neurologic check; severe head injuries—major facial fractures and depressed skull fractures; can lead to unconsciousness; consult with and involve neurology specialists; appropriate use of radiologic studies (eg, CT); management—secure airway and oxygenate patient; to avoid worsening cervical spine injury, exercise caution in placing endotracheal tube (involve anesthesiologist); appropriate use of mannitol and/or steroids to reduce ICP

Burn injuries: partial- or full-thickness; minor, <10% of total body surface; moderate, 10% to 19%; severe, 20% to 39%; critical, >40%; >80% associated with 100% maternal and perinatal mortality; presume smoke inhalation if patient unconscious; management—chest evaluation, chest x-rays; debridement and cleansing; appropriate use of antibiotics (note that fluoroquinolones and “cyclones” [eg, doxycycline] contraindicated in pregnancy; stillbirth or preterm labor can occur); use caution with magnesium since patient already has electrolyte imbalance (consider indomethacin instead); avoid beta-mimetics because of hemodynamic instability; consider delivery if patient near term

Perimortem cesarean delivery: perform only after full (not impending) cardiopulmonary arrest by mother; longest reported time after loss of maternal vital signs in which fetus survived, ≈20 min; perform cesarean delivery within 4 min after arrest for fetal and maternal benefit