Evaluation of cerebral perfusion pressure changes in laboring women: effects of epidural anesthesia

A Case Report of Spontaneous Vaginal Delivery Under General Anesthesia in a Patient With a Large Cerebral Aneurysm

Cerebral aneurysms are rarely encountered in pregnancy. Their antepartum and intrapartum management remain clinically challenging, primarily due to concern regarding potential rupture. We present a case of a patient in preterm labor at risk for imminent delivery with a 10mm cerebral aneurysm. She was recommended for cesarean section (CS), yet delivered via spontaneous vaginal delivery in the operating room after induction of general anesthesia for the intended CS. Her aneurysm and neurologic function remained intact postpartum. Cerebral aneurysms <5mm are unlikely to undergo significant growth during pregnancy. The presence of a cerebral aneurysm is not automatically a contraindication to the Valsalva maneuver. The recommendation for which patients with unruptured cerebral aneurysms should deliver by CS, operative vaginal delivery, or unassisted vaginal delivery (i.e., which patients should avoid Valsalva maneuver intrapartum), is complex and requires multidisciplinary discussion.

Low maternal middle cerebral artery Doppler resistance indices can predict future development of pre-eclampsia

OBJECTIVE

To determine if decreased resistance (vasodilatation) in the maternal middle cerebral artery (MCA) in the second trimester can predict third-trimester development of pre-eclampsia.

METHODS

Four-hundred and five low-risk gravidas had MCA transcranial Doppler (TCD) once in the second trimester. Maternal/neonatal outcomes were evaluated after delivery. Mean blood pressure, MCA velocities, resistance index (RI), pulsatility index (PI) and cerebral perfusion pressure (CPP) were compared between normotensive and pre-eclamptic cohorts.

RESULTS

Seven subjects (1.7%) developed pre-eclampsia. An RI of < 0.54 and a PI of < 0.81 were clinically useful in predicting subsequent pre-eclampsia. Areas under the receiver-operating characteristics curves for RI and PI were 0.93 and 0.93, respectively, with optimal sensitivity and specificity of 86% and 93% for both variables. Positive and negative likelihood ratios were 11.8/0.15 (RI) and 12.3/0.15 (PI).

CONCLUSION

TCD indices of low maternal MCA resistance in the second trimester are predictive of the subsequent development of pre-eclampsia in a low-risk, ethnically homogeneous population.

Magnesium sulfate decreases cerebral perfusion pressure in preeclampsia

OBJECTIVE

To determine the cerebral hemodynamic effect of magnesium sulfate (MgSO4) in preeclampsia.

DESIGN

Prospective observational study.

SETTING

Tertiary Care Medical Center.

POPULATION

Preeclamptic patients (systolic < 160, diastolic < 110 mmHg).

METHODS

Transcranial Doppler (TCD) of the middle cerebral arteries (MCA) of 15 preeclamptics, before and after IV MgSO4. No vasoactive drugs other than MgSO4 were given. 11 patients with mild range BP (140/90-160/110 mmHg) had measurements at baseline, 30 and 120 minutes after MgSO4, and 7 patients with elevated CPP had baseline and 30 minute measurements. Hemodynamic parameters were compared with normative curves.

MAIN OUTCOME MEASURES

Mean arterial pressure (MAP), heart rate (HR), cerebral perfusion pressure (CPP), resistance index (RI), resistance area product (RAP), and cerebral flow index (CFI).

RESULTS

Eight women had normal baseline CPP, and 11 had normal CFI. 11 had mild preeclampsia range blood pressure and MgSO4 had no significant effect on CPP, CFI, HR, MCA velocities, or RAP but did decrease the MAP in the first 30 minutes (107 +/- 8 to 100 +/- 9 mmHg; p = 0.035), mainly due to a drop in diastolic pressure (87 +/- 10 to 82 +/- 9 mmHg; p = 0.004). 7 patients with elevated baseline CPP had a significant reduction in CPP, but no change in CFI, after MgSO4.

CONCLUSIONS

MgSO4 does not significantly effect CPP or CFI in preeclamptics with baseline blood pressure in the mild range, but does significantly reduce CPP in those with high baseline CPP. This may be important in the prevention of hypertensive encephalopathy.

Labetalol decreases cerebral perfusion pressure without negatively affecting cerebral blood flow in hypertensive gravidas

OBJECTIVE

To research the cerebral hemodynamic effects of labetalol in pregnant women with hypertension.

DESIGN

Prospective observational study.

SETTING

Tertiary Care Medical Center.

POPULATION

Pregnant patients with hypertension.

METHODS

Transcranial Doppler (TCD) ultrasound was used to measure the blood velocity in the middle cerebral arteries (MCA) of eight pregnant patients with hypertension, before and after the administration of a 200 mg oral dose of labetalol. Five patients had severe preeclampsia, and three had chronic hypertension with superimposed preeclampsia. MCA blood velocity and systemic blood pressure were measured simultaneously at the baseline, and at 60 and 180 min after labetalol. Selected cerebral hemodynamic parameters were compared with normative curves. Values outside of the 5th and 95th percentiles were regarded as abnormal.

MAIN OUTCOME MEASURES

Cerebral perfusion pressure (CPP), resistance area product (RAP), and cerebral flow index (CFI).

RESULTS

Patient age, gestational age, and parity were similar to those of the normal women from whom the normative data were obtained. Women with hypertension had higher baseline CPP, MAP, and RAP than normal pregnant women, but their CFI was within the normal range. Labetalol reduced the CPP, as well as the systolic, diastolic, and mean BP significantly at 60 and 180 min without significantly affecting the heart rate, MCA velocities, RAP, or CFI.

CONCLUSIONS

Labetalol effectively reduces CPP, without affecting cerebral perfusion, primarily by a decrease in systemic blood pressure. This makes it an ideal agent for blood pressure control in severely hypertensive pregnant women.