Key Clinical Questions
What are physiologic changes of pregnancy pertinent to critical care?
What are common reasons for pregnant women to require critical care?
What factors impact airway intubation during pregnancy?
What issues arise in hemodynamic monitoring during pregnancy?
What vasopressors can and should be used during pregnancy?
Are there special considerations for resuscitation during pregnancy?
The majority of critical care admissions for pregnant and peripartum women are for obstetric disorders, primarily hypertensive complications (particularly hemorrhagic stroke) or hemorrhage. Medical indications, such as sepsis, respiratory failure, cardiomyopathy, or ischemic stroke are less common. Maternal mortality in developed nations remains rare (650 in the United States annually); however, the proportion attributable to medical disorders has been increasing as women with underlying medical conditions and older women conceive, perhaps with assisted reproductive technology. Standard scoring systems, such as APACHE scores, overestimate mortality in pregnant and peripartum women, particularly if they have an obstetric indication for critical care. Delivery or surgery may contribute to rapid improvement. A small proportion of obstetric patients, approximately 12 per 1000, require critical care. Hospitalists and intensivists may have limited experience managing these patients.
Virtually every organ system adapts to accommodate pregnancy and delivery. Hemodynamic alterations prepare for blood loss of one-half to 1 L at delivery. Blood volume increases by 50% (Table 220-1).
TABLE 220-1Cardiac, Respiratory and Hematologic Physiologic Changes in Pregnancy ||Download (.pdf) TABLE 220-1 Cardiac, Respiratory and Hematologic Physiologic Changes in Pregnancy
| ||Direction of Change ||Percentage of Change or Normal Range in Pregnancy |
|Blood volume ||↑ ||30%-40% increase |
|Heart rate ||↑ ||Increases by 10-20 bpm |
|Cardiac output ||↑ ||30%-60% increase |
|Systemic vascular resistance ||↓ ||25%-30% decrease |
|Blood pressure ||↓ ||10-15 mm Hg decrease in first two trimesters |
|Colloid oncotic pressure ||↓ ||10%-15% decrease |
|Total lung capacity ||↓ ||4%-5% decrease |
|Functional residual capacity ||↓ ||20% decrease |
|Diffusion capacity ||↔ ||No change |
|Tidal volume ||↑ ||Increased |
|Respiratory rate ||↔ ||No change |
|Minute ventilation ||↑ ||50% increase |
|PaO2 ||↑ ||Average 100-105 |
|PcaCo2 ||↓ ||Average 28-32 |
|pH ||↑ ||Mild respiratory alkalosis |
|A-a gradient ||↑ ||Increase in late gestation to approximately 20 |
|Protein S ||↓ || |
|Activated protein C resistance, fibrinogen, factor V, VIII, IX, X ||↑ || |
|Plasminogen activator inhibitor type 1 and 2 ||↑ || |
|Activity of tissue plasminogen ||↓ || |
Cardiac output increases by 30% to 50% and total peripheral resistance decreases by 20%, leading to blood pressure declining by 10 to 15 mm Hg in the first half of pregnancy, then returning to baseline in the second half. Diastolic blood pressure decreases more than systolic; pulse pressure is widened. Central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) remain unchanged. Blood flow distribution ...