Cardiovascular Alterations in the Parturient Undergoing Cesarean Delivery With Neuraxial Anesthesia

Katherine W Arendt; Jochen D Muehlschlegel; Lawrence C Tsen

Disclosures

Expert Rev of Obstet Gynecol. 2012;7(1):59-75. 

In This Article

Patient Populations With Variations in Hemodynamic Responses

Preeclampsia

Baseline maternal hemodynamic parameters in preeclampsia differ from those in a healthy pregnancy. The majority, but not all,[110,111] studies have found preeclampsia to be a low CO state accompanied by high SVR.[40,112–114] Because preeclampsia progresses in a unique way in individual pregnancies and is frequently accompanied by comorbid conditions such as renal disease or chronic hypertension, there are no formulas to indicate how each individual's hemodynamic profile will respond to interventions, such as neuraxial anesthesia. Treatment with magnesium, tocolytics or antihypertensive medications further alters the hemodynamic state.

Traditionally, the epidural technique was considered the neuraxial anesthetic of choice for CD in severe preeclampsia, due to the demonstration that lesser hemodynamic changes would be observed, when compared with a spinal technique.[115,116] However, recent, prospective studies have challenged this belief, indicating that the frequency and severity of hypotension associated with spinal anesthesia was less in preeclamptic women than in healthy women.[117–119] Furthermore, some prospective and retrospective studies have shown no significant differences in hemodynamic shifts when spinal and epidural local anesthetic techniques for CD have been compared.[120–122] Moreover, some of these studies have indicated that the hypotension produced was short-lived, easily treated and did not affect neonatal outcomes.[123] One study showed insignificant changes in uterine artery velocity waveforms when SBP was maintained at 80% baseline,[116] and another observed clinically insignificant CO changes following spinal anesthesia in severe preeclampsia.[62] Therefore, one author has concluded, "spinal anesthesia in stable and non-coagulopathic severely preeclamptic women is a reasonable alternative to epidural block, especially in emergency situations and particularly if it avoids the use of general anesthesia".[123]

Multifetal Gestation

Multifetal gestation introduces a number of hemodynamic derangements. Twin gestations are associated with a 10% greater increase in maternal blood volume[124] and a 20% greater increase in CO than a singleton pregnancy.[125] The diastolic blood pressure of parturients with twin gestations is associated with a lower nadir during the second trimester and greater increases as the third trimester progresses when compared with a singleton pregnancy.[126] Aortocaval compression is more common because of the greater uterine size, and blood loss with delivery is greater. Because of these exaggerated hemodynamic variables, parturients with multifetal gestations were believed to experience greater hemodynamic instability during CD under neuraxial anesthesia. However, a recent prospective study observed that parturients with multifetal gestation undergoing spinal anesthesia for CD did not have a greater incidence of hypotension or vasopressor requirements in comparison with parturients with singleton gestations.[127]

Parturient With Cardiac Disease

Up to 3% of deliveries are complicated by maternal heart disease. The presence of intracardiac shunting, cyanosis, left heart obstruction, and decreased left or right heart function will affect the hemodynamics that occur during cesarean delivery under neuraxial anesthesia. Some cardiac lesions (e.g., mitral stenosis, aortic stenosis, aortic coarctation or right-to-left shunting) could lead to significant decompensation with the SVR reduction associated with pregnancy and with the onset of neuraxial anesthesia for cesarean delivery. At times, general anesthesia may be indicated. If neuraxial anesthesia is the anesthetic of choice, maintenance of hemodynamic stability employing the techniques as described in Box 1 is important.

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