Keith Williams

Persistence of cerebral hemodynamic changes in patients with eclampsia: A report of three cases.

OBJECTIVEnThis study was undertaken to compare the persistence of changes in estimated cerebral perfusion pressure and the resistance area product, an index of cerebrovascular resistance, in women with preeclampsia and women with eclampsia.nnnSTUDY DESIGNnThe maternal middle cerebral artery was evaluated by transcranial Doppler ultrasonography in 6 patients with severe preeclampsia and 3 women with eclampsia, and cerebral blood flow velocities were determined. Estimated cerebral perfusion pressure was calculated according to the following equation: Estimated cerebral perfusion pressure = Mean cerebral blood flow velocity/(Mean cerebral blood flow velocity - Diastolic cerebral blood flow velocity) x (Mean blood pressure - Diastolic blood pressure). Because the diameters of the vessels could not be measured directly, an index of resistance was calculated according to the following equation: Resistance area product = Mean blood pressure/Mean cerebral blood flow velocity. We calculated an index of cerebral blood flow according to the following equation: Index = Estimated cerebral perfusion pressure/Resistance area product. Patients were reassessed at 24 and 48 hours after delivery.nnnRESULTSnAt the initial assessment the estimated cerebral perfusion pressure was higher in women with eclampsia than in those with severe preeclampsia. In addition, cerebrovascular resistance was significantly decreased in the eclampsia group, and it remained decreased as long as 4 days in 1 patient with eclampsia.nnnCONCLUSIONSnPreeclampsia is associated with increases in cerebral perfusion pressure counterbalanced by increases in cerebrovascular resistance, with no change in cerebral blood flow. In eclampsia a significant increase in cerebral perfusion pressure occurs, but a significant fall in cerebrovascular resistance also occurs and a loss of autoregulation results in cerebral overperfusion similar to that of hypertensive encephalopathy. This may persist for as long as 4 days.

Changes in cerebral perfusion pressure in puerperal women with preeclampsia.

Objective To determine the variation in the estimated maternal cerebral perfusion and cerebrovascular resistance (the resistance area product) in the puerperium. Methods The maternal middle cerebral artery was evaluated by transcranial Doppler ultrasound in ten women 2 days before labor, in 21 women in early labor and at 24 and 48 hours postpartum, and in 6 women at 1 week postpartum. Cerebral blood flow velocities were determined. Women were diagnosed initially with mild preeclampsia. Estimated cerebral perfusion pressure was Vmean/[Vmean – Vdiastolic] [BPmean – BPdiastolic]. Because the diameter of the vessels could not be measured directly, an index of resistance was calculated: the resistance area product = BPmean/velocitymean. We calculated an index of cerebral blood flow to be estimated cerebral perfusion pressure divided by resistance area product. Our study had a power of 80% to detect a 16-cm/second increase in middle cerebral blood flow velocity. Results Estimated maternal cerebral perfusion was maintained for up to 1 week postpartum. Cerebrovascular resistance did not change in the puerperium. Cerebral blood flow index (±standard deviation) was significantly increased at 1 week postpartum compared with early labor levels (28.3 ± 6.9 versus 46.7 ± 15.6, respectively) (P < .05). Conclusion Cerebral blood flow 1 week postpartum increased significantly over early labor values. These persistent changes in the cerebral vasculature might put patients at risk for seizures up to 1 week postpartum.

Correlation of subjective assessment of amniotic fluid with amniotic fluid index

We assessed the correlation between abnormal amniotic fluid volumes as defined by the two techniques of (1) subjective evaluation and (2) the amniotic fluid index. Ultrasound evaluation of amniotic fluid volume was conducted on 420 pregnant women with known gestational age greater than twenty weeks but less than 42 weeks. Amniotic fluid was evaluated subjectively and placed into one of three categories: normal, oligohydramnios or polyhydramnios. After fetal biometry was performed, the amniotic fluid volume was assessed semi-quantitatively by the amniotic fluid index technique and assigned to similar categories. We analyzed the data with 2 x 2 contingency tables, using amniotic fluid index as the gold standard test. Our study demonstrates that there was moderate agreement (kappa.5) between both amniotic fluid techniques in the identification of oligohydramnios. However, agreement between the techniques was poor for the identification of polyhydramnios (kappa.16).

Antepartum Middle Mean Cerebral Blood Flow Velocity Correlation with Maternal Hemodynamics

OBJECTIVEnTo determine the correlation between simultaneous assessment of maternal middle cerebral blood flow velocity with the other maternal hemodynamic factors of cardiac output and mean arterial pressure.nnnSTUDY DESIGNnEight normotensive patients were assessed. Maternal cerebral blood flow velocity was assessed using transcranial Doppler. Cardiac output was assessed noninvasively using the thoracic electrical bioimpedance technique over four cycles. Transcranial assessment of cerebral blood flow velocity was done over four cycles. Statistical analysis was then done using the Pearson correlation coefficient and linear regression analysis with stepwise regression. A p-value of < 0.05 was considered significant.nnnRESULTSnThe value of the hemodynamic parameters were cardiac output 8.6 +/- 2.6 L/min, mean arterial pressure 82 +/- 9.7 mm Hg, and mean maternal cerebral blood flow velocity 59.6 +/- 11 cm/s. The pulsatility index was 0.85 +/- 0.15. The mean blood pressure could only explain 42% of the variation in systolic maternal cerebral blood flow velocity and 32% of the variation in mean maternal cerebral blood flow velocity. The mean middle cerebral blood flow velocity did not correlate with cardiac output.nnnCONCLUSIONSnMiddle cerebral artery velocity correlates moderately with mean arterial pressure but not with cardiac output. The control of mean arterial pressure cannot be used as the only indicator of appropriate reduction in cerebral blood flow velocity.

Kyphoscoliosis and Pregnancy: A Case Report and Review of the Literature

Abstract this case report of a woman with severe (Grade IV) kyphoscoliosis describes the complexities of providing care to women with this debilitating maternal condition. The literature was reviewed for the related obstetrical management issues associated with kyphoscoliosis and pregnancy. Incidence and causes of kyphoscoliosis are described, as well as recognized methods of determining the severity of spinal curvature. The three health considerations for pregnant women with kyphoscoliosis are reviewed. Cardiopulmonary complications may arise in women with primary curvature in the thoracic spine. Conversely, women with the primary curvature in the lumbar spine have a higher risk of such obstetrical complications as cephalopelvic disproportion. Finally, a concern in women with kyphoscoliosis is whether pregnancy will worsen spinal curvature. This article emphasizes the importance of a multidisciplinary approach in caring for obstetrical patients with kyphoscoliosis.

The Role of Ethnicity in the Development of Pre-eclampsia

Abstract Hypertension in pregnancy complicates seven to ten percent of all pregnancies and remains a major cause of maternal and perinatal morbidity and mortality. A variety of factors including ethnic or cultural issues have been suggested to affect the development of pre-eclampsia. An ethnic group is a group of people who share a common ancestorial history and who have a distinct pattern of family life, language, values and social norms. Studies of several populations have been performed. Higher levels of pre-eclampsia were documented in the non-Jews, mainly Muslim Arabs, and Iranian immigrants from Iraq. A higher incidence of pre-eclampsia was found in the East Indian population (14.6%) in Trinidad than in the Black population (6.3%). Differences in the incidence of pre-eclampsia which may be related to dietary intake and other genetic factors have been documented in different ethnic groups.

Intussusception During Pregnancy: A Case Report and Review of the Literature

Abstract Intussusception is an extremely rare occurrence during pregnancy. The non-specific presenting symptoms may be attributed to the pregnancy itself, making the diagnosis difficult. We report a case in which the use of ultrasound led to the prompt suspicion of the diagnosis.

Maternal Cerebral Changes With Pre-eclampsia Assessed by Transcranial Doppler: A Review

Abstract Pre-eclampsia is the most frequent complication of pregnancy. Its aetiology is unknown, and delivery is the only definitive treatment to cure the maternal condition. All tests used to assess cerebral changes in pre-eclampsia e.g. computerized tomography are invasive, expensive, and non-repeatable. It is now possible to measure maternal cerebral vasospasm in pre-eclamptic patients with the non-invasive technique of transcranial Doppler. This technique is relatively simple. Using transcranial assessment of cerebral blood flow velocity we have identfied: (i) the development of cerebral vasospasm in eclampsia; (ii) the changes in maternal cerebral blood flow velocity with gestational age, although these changes have not been shown to correlate with mean arterial pressure; (iii) changes in posture significantly affect cerebral blood flow velocity; (iv) pre-eclamptic patients in labour show a significant rise in middle cerebral blood flow velocity in the post-partum phase. Long term studies are required, especially in the use of medications to treat pre-eclampsia, to determine the effect on maternal cerebral circulation.

Perinatal Outcome in Vaginally Delivered Triplet Pregnancies: A Case Control Study and Review of the Literature

Abstract Objective: to determine if there is a significant difference in immediate perinatal morbidity and mortality in triplets selected for delivery vaginally compared to delivery by Caesarean section. Study Design: over a ten-year period, 57 triplet pregnancies were delivered at the B.C.’s Women’s Hospital. In four cases, vaginal delivery of triplets was attempted. Criteria for attempted vaginal delivery included: (i) gestational age greater than 33 weeks, (ii) triplet A with a cephalic presentation, (iii) no evidence of fetal distress, A case controlled study was performed comparing the four vaginal deliveries to eight triplet pregnancies delivered by Caesarean section, matched for: (i) fetal presentation, (ii) multiparity, (iii) gestational age. Outcome variables compared included: (i) birthweight, (ii) Apgar scores at one and five minutes, (iii) length of stay in the Special Care Nursery (SCN) and evidence of trauma associated with delivery. Maternal outcome characteristics included: post-partum haemorrhage, infection, and maternal length of stay. Means were compared by student t-test and categorical variables were compared using chi-squared analysis. Results: our study revealed no significant difference in perinatal outcome between the triplets (A, B or C) delivered vaginally as compared to Caesarean section. However, a statistically significant increase in estimated maternal bleeding (875cc versus 600) and hospital stay (6 versus 4 days) for the Caesarean section group compared with the vaginal group were noted. Conclusion: in selected cases with gestational age greater than 33 weeks and triplet A cephalic, attempted vaginal delivery is not associated with any increase in adverse perinatal outcome and may be offered.