From the Guidelines
Normal parameters for invasive hemodynamic monitoring during pregnancy include a central venous pressure (CVP) of 3-8 mmHg, pulmonary capillary wedge pressure (PCWP) of 6-12 mmHg, cardiac output of 6-7 L/min, systemic vascular resistance of 800-1200 dyne·sec/cm5, mean arterial pressure above 65 mmHg, pulmonary artery systolic pressure of 15-30 mmHg, and diastolic pressure of 8-15 mmHg, with a heart rate increase of 10-20 beats per minute above pre-pregnancy baseline. These parameters are based on the physiological adaptations that occur during pregnancy, which include an increase in blood volume, cardiac output, and a decrease in systemic vascular resistance to accommodate the growing fetus and placenta 1. The hemodynamic changes associated with pregnancy begin during the first trimester and peak at 20 to 24 weeks of gestation, with further increases in cardiac output during labor and marked volume shifts immediately postpartum 1.
When interpreting hemodynamic values, clinicians should consider gestational age, as most changes are most pronounced by the late second trimester and remain relatively stable until delivery. The use of a pulmonary artery catheter for close hemodynamic monitoring may be helpful in managing pregnant patients with pulmonary arterial hypertension (PAH) 1. It is essential to note that pregnancy remains associated with a substantial mortality risk in patients with PAH, and most experts recommend effective contraception and consideration of early termination if pregnancy occurs in a patient with PAH 1.
Key parameters to monitor during invasive hemodynamic monitoring in pregnancy include:
- Central venous pressure (CVP): 3-8 mmHg
- Pulmonary capillary wedge pressure (PCWP): 6-12 mmHg
- Cardiac output: 6-7 L/min
- Systemic vascular resistance: 800-1200 dyne·sec/cm5
- Mean arterial pressure: above 65 mmHg
- Pulmonary artery systolic pressure: 15-30 mmHg
- Diastolic pressure: 8-15 mmHg
- Heart rate: 10-20 beats per minute above pre-pregnancy baseline.
These parameters should be interpreted in the context of gestational age and the individual patient's clinical condition, taking into account the potential risks and complications associated with pregnancy in patients with PAH 1.
From the Research
Normal Invasive Hemodynamic Monitoring Parameters During Pregnancy
The following are the normal parameters for invasive hemodynamic monitoring during pregnancy:
- Cardiac output (CO) increases by almost 50% from the non-pregnant level to that at 8-11 weeks gestation, and then gradually falls until delivery 2
- Systemic vascular resistance (SVR) is influenced by maternal age, height, and weight, with greater height associated with lower median values of SVR 3
- Stroke volume (SV) increases significantly from a median of 31 ml in the non-pregnant state to 51 ml in early pregnancy, and remains at this level until delivery 2
- Central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) do not always agree, with a mean difference of 3.5 +/- 2.6 mm Hg in untreated patients and 4.9 +/- 3.8 mm Hg in posttreatment data 4
Factors Influencing Hemodynamic Parameters
Several factors can influence hemodynamic parameters during pregnancy, including:
- Maternal age: advancing maternal age is associated with higher median SVR 3
- Maternal height: greater height is associated with lower median values of SVR and higher SV 3
- Maternal weight: maternal weight significantly affects CO values, with an increase in weight associated with an increase in CO in women with a height exceeding 1.60 m 3
- Smoking: smokers have a lower SVR by 73.5 (95% CI, 8.6-138.4) dynes × s/cm5 3
Measurement of Hemodynamic Parameters
Several methods can be used to measure hemodynamic parameters during pregnancy, including: