Teelkien Van Veen

Cerebral Autoregulation in Normal Pregnancy and Preeclampsia

OBJECTIVE: To test the hypothesis that preeclampsia is associated with impaired dynamic cerebral autoregulation. METHODS: In a prospective cohort analysis, cerebral blood flow velocity of the middle cerebral artery (determined by transcranial Doppler), blood pressure (determined by noninvasive arterial volume clamping), and end-tidal carbon dioxide were simultaneously collected during a 7-minute period of rest. The autoregulation index was calculated. Values of 0 and 9 indicated absent and perfect autoregulation, respectively. Student t test was used, with P<.05 considered significant. RESULTS: Women with preeclampsia (before treatment, n=20) and their normotensive counterparts (n=20) did not differ with respect to baseline characteristics, except for earlier gestational age at delivery (36 3/7 [24 4/7–40 2/7] compared with 39 2/7 [32 0/7–41 0/7]; P<.001) and higher blood pressure in women with preeclampsia. Autoregulation index was significantly reduced in preeclamptic women compared with normotensive women in the control group (5.5±1.7 compared with 6.7±0.6; P=.004). There was no correlation between the autoregulation index and blood pressure. CONCLUSION: Women with preeclampsia have impaired dynamic cerebral autoregulation. The fact that blood pressure does not correlate with autoregulation functionality may explain why cerebral complications such as eclampsia can occur without sudden or excessive elevation in blood pressure. LEVEL OF EVIDENCE: II

Neonatal side effects of maternal labetalol treatment in severe preeclampsia

OBJECTIVE Labetalol is often used in severe preeclampsia (PE). Hypotension, bradycardia and hypoglycemia are feared neonatal side effects, but may also occur in (preterm) infants regardless of labetalol exposure. We analyzed the possible association between intrauterine labetalol exposure and such side effects. STUDY DESIGN From 1 January 2003 through 31 March 2008, all infants from mothers suffering severe PE admitted to one tertiary care center were included. Severe PE was defined according to the International Society for the Study of Hypertension in Pregnancy (ISSHP) criteria. Infants exposed to labetalol in utero (labetalol infants) were compared with infants, who were not exposed to labetalol (controls). Neonatal records were reviewed for hypotension (RR<mean gestational age in weeks), bradycardia (heartrate<100/min) and hypoglycaemia (glucose<2.7 mmol/L) in the first 48 postnatal hours. RESULTS Of 109 infants, 55 had been exposed to labetalol, whereas 54 were not (controls). Gestational age at delivery and birthweight were similar in both groups (31.8 vs. 32.8 weeks (p=0.06) and 1510 vs. 1639 grams (p=0.25), respectively for the labetalol vs. control group). Hypotension occurred significantly more in conjunction with labetalol exposure (16, (29.1%) vs. 4 (7.4%); p=0.003), irrespective of the route of administration. Patent ductus arteriosus (PDA) was present in 9 (56%) of hypotensive labetalol infants compared to 1 (24%) infant in the hypotensive control group (NS). In a multivariate regression model, labetalol exposure, the need for intubation and PDA appeared independently associated with hypotension (P<0.001). Hypoglycemia occurred in 26 (47.3%) of labetalol infants and in 23 (42.6%) of control infants (p=0.62). Bradycardia occurred in 4 (7.3%) of labetalol infants and in 1 (1.9%) of control infants (p=0.18). Hypoglycemia was more common in premature infants (n=45 (48,9%) vs. n=4 (23.5%), p=0.05) in both labetalol and control infants. CONCLUSION Hypotension is more common after maternal labetalol exposure, regardless of the dosage and route of administration. The need for intubation and the presence of a PDA also play a role. Hypoglycemia is a very common finding in this population and is merely related to prematurity and independent of labetalol exposure as was the incidental occurrence of bradycardia. These findings on the neonatal side effects of maternal labetalol treatment in preeclampsia underline the importance of frequent blood glucose and blood pressure measurements in the first days of life, especially in intubated preterm infants with a PDA.

Maternal heart rate patterns in the first and second stages of labor

Objective. To analyze typical maternal heart rate (MHR) patterns in the first and second stages of labor. Design. Observational study. Setting. Tertiary care community hospital. Population. Normal term parturients with epidural anesthesia. Methods. Confirmed MHR and uterine activity were simultaneously recorded. The average MHR was analyzed 10 seconds before, as well as at the peak of, each contraction and/or pushing effort. Each woman contributed one datapoint at each time point to the analysis. Main outcome measure. Change in MHR during contractions. Results. First stage: 7.6±2.1 contractions per woman (n=18) were analyzed. Average MHR decreased during contractions: from 83±13 to 74±10bpm; p<0.001). In 56% (10/18) of the women, ‘early’ type decelerations were seen in at least 50% of contractions. Second stage: 3.5±1.5 contractions per woman. All women (n=15) showed MHR accelerations during every pushing effort (ΔMHR: +35±13bpm; 88±14 to 123±17bpm; p<0.001). MHR was persistently >100bpm in three women (17%) in the first stage, and in four women (27%) in the second stage. Peak MHR >140bpm occurred during pushing in 20%. Conclusion. Decreases in MHR during contractions in the first stage of labor can mimic fetal heart rate (FHR) accelerations as well as early type decelerations. Thus, first stage tracings with a low baseline and early type decelerations may be maternal in origin and FHR should be independently confirmed in such tracings. Because second stage MHR accelerations generally show greater amplitude than FHR accelerations, tracings with repetitive accelerations during contractions (especially when Δ >20bpm) should be considered MHR until proven otherwise.

Effect of breath holding on cerebrovascular hemodynamics in normal pregnancy and preeclampsia

Preeclampsia (PE) is associated with endothelial dysfunction and impaired autonomic function, which is hypothesized to cause cerebral hemodynamic abnormalities. Our aim was to test this hypothesis by estimating the difference in the cerebrovascular response to breath holding (BH; known to cause sympathetic stimulation) between women with preeclampsia and a group of normotensive controls. In a prospective cohort analysis, cerebral blood flow velocity (CBFV) in the middle cerebral artery (transcranial Doppler), blood pressure (BP, noninvasive arterial volume clamping), and end-tidal carbon dioxide (EtCO2) were simultaneously recorded during a 20-s breath hold maneuver. CBFV changes were broken down into standardized subcomponents describing the relative contributions of BP, cerebrovascular resistance index (CVRi), critical closing pressure (CrCP), and resistance area product (RAP). The area under the curve (AUC) was calculated for changes in relation to baseline values. A total of 25 preeclamptic (before treatment) and 25 normotensive women in the second half of pregnancy were enrolled, and, 21 patients in each group were included in the analysis. The increase in CBFV and EtCO2 was similar in both groups. However, the AUC for CVRi and RAP during BH was significantly different between the groups (3.05 ± 2.97 vs. -0.82 ± 4.98, P = 0.006 and 2.01 ± 4.49 vs. -2.02 ± 7.20, P = 0.037), indicating an early, transient increase in CVRi and RAP in the control group, which was absent in PE. BP had an equal contribution in both groups. Women with preeclampsia have an altered initial CVRi response to the BH maneuver. We propose that this is due to blunted sympathetic or myogenic cerebrovascular response in women with preeclampsia.

Gout in pregnancy: a case report and review of the literature.

While gout is a common inflammatory joint disease, its occurrence in women in their reproductive years is very rare. This is thought to be the result of the uricosuric effect of estrogen. The higher estrogen levels during pregnancy are believed to protect the mother against an acute gout flare. We report a case of a patient with gout who experienced a flare in the third trimester of her pregnancy and a review of the English literature on gout in pregnancy. In addition to this case, we identified 19 pregnancies in 8 women with a diagnosis of gout. Of those, 6 experienced an antepartum flare and 7 a postpartum flare. Our patient developed a gout flare in the third trimester of the pregnancy, which was otherwise complicated by gestational diabetes. Her flare was well controlled with pharmacotherapy (hydrocodone and allopurinol). We hypothesize that her pregnancy induced insulin resistance, which decreased the renal excretion of urate provoked this flare. Little is known about the treatment of acute gout and long-term management during pregnancy. The initiation of preventive treatment with allopurinol should be based on individualized risks and benefits, but we suggest that gestational diabetes justifies its use in the second half of pregnancy.

Changes in Maternal Posterior and Anterior Cerebral Artery Flow Velocity During Pregnancy and Postpartum-A Longitudinal Study

To evaluate the normal range of blood flow velocity in the maternal anterior (ACA) and posterior cerebral arteries (PCA) along the normal pregnancy and postpartum period.

Changes in cerebral autoregulation in the second half of pregnancy and compared to non-pregnant controls

OBJECTIVE The mechanism by which pregnancy affects the cerebral circulation is unknown, but it has a central role in the development of neurological complications in preeclampsia, which is believed to be related to impaired autoregulation. We evaluated the cerebral autoregulation in the second half of pregnancy, and compared this with a control group of healthy, fertile non-pregnant women. METHODS In a prospective cohort analysis, cerebral blood flow velocity of the middle cerebral artery (determined by transcranial Doppler), blood pressure (noninvasive arterial volume clamping), and end-tidal carbon dioxide (EtCO2) were simultaneously collected for 7min. The autoregulation index (ARI) was calculated. ARI values of 0 and 9 indicated absent and perfect autoregulation, respectively. ANOVA and Pearsons correlation coefficient were used, with p<0.05 considered significant. RESULTS A total of 76 pregnant and 18 non-pregnant women were included. The ARI did not change during pregnancy, but pregnant women had a significantly higher ARI than non-pregnant controls (ARI 6.7±0.9 vs. 5.3±1.4, p<0.001). This remained significant after adjusting for EtCO2 (p<0.001). CONCLUSION Cerebral autoregulation functionality is enhanced in the second half of pregnancy, when compared to non-pregnant fertile women, even after controlling for EtCO2. The autoregulation does not change with advancing gestational age.

Cerebral autoregulation in pregnancies complicated by diabetes and overweight.

Aim: The aim of this study was to estimate the impact of diabetes and obesity on cerebral autoregulation in pregnancy. Methods: Cerebral autoregulation was evaluated in women with gestational diabetes, type 2 diabetes mellitus and/or overweight (body mass index ⩾ 25 kg m−2) and compared to a cohort of euglycaemic pregnant women. The autoregulation index was calculated using simultaneously recorded cerebral blood flow velocity in the middle cerebral artery and blood pressure. Autoregulation index values of 0 and 9 indicate absent and perfect autoregulation, respectively. Results: Autoregulation index in women with either diabetes (n = 33, 6.6 ± 1.1) or overweight (n = 21, 6.7 ± 0.6) was not significantly different to that in control patients (n = 23, 6.6 ± 0.8, p = 0.96). Conclusion: Cerebral autoregulation is not impaired in pregnant women who have non-vasculopathic diabetes or overweight. This suggests that the increased risk of pre-eclampsia in diabetic and overweight women is not associated with early impaired cerebral autoregulation.

Power M-mode transcranial Doppler examination of the ophthalmic artery in pregnancy: standard operating procedure and review of the literature.

Our aim was to describe the standard operating procedure for transcranial Doppler investigation of the ophthalmic artery in pregnancy, determine the interobserver and intraobserver variability using power M‐mode technology, and review the existing literature. Accordingly, 27 healthy pregnant or immediately postpartum women were enrolled and underwent transcranial Doppler investigation of the ophthalmic artery using power M‐mode technology. Good interobserver and intraobserver variability was observed for both, especially with respect to the clinically important indices. Transcranial Doppler power M‐mode examination of the ophthalmic artery is easy and reproducible and holds a great deal of potential for investigation in pregnancy.

The effect of neuraxial anesthesia on maternal cerebral hemodynamics

OBJECTIVE Neuraxial anesthesia is known to reduce sympathetic tone and mean arterial pressure. Effects on cerebral hemodynamics in pregnancy are not well known. We hypothesize that cerebral hemodynamic parameters will change with respect to baseline following regional analgesia/anesthesia. STUDY DESIGN We performed maternal transcranial Doppler of the middle cerebral artery in 20 women receiving epidural analgesia for labor, and 18 undergoing spinal anesthesia for cesarean section at baseline, 5 and 15 minutes. Systemic blood pressure (BP), systolic/diastolic/mean velocity, resistance and pulsatility index (PI) were recorded. Cerebral perfusion pressure, critical closing pressure (CrCP), resistance area product, and cerebral flow index were calculated. RESULTS Epidural placement was associated with significant decreases in systolic/diastolic BP/mean velocity/CrCP after 15 minutes, with a corresponding increase in PI. In the spinal group, systolic/diastolic BP/mean velocity uniformly decreased and remained low after 15 minutes, and PI significantly increased and remained constant after 15 minutes. No differences were seen in BP or cerebral hemodynamics between the groups. CONCLUSION This study demonstrates that both epidural analgesia and spinal anesthesia result in measurable cerebral hemodynamic changes in normotensive term pregnancy that are likely to be clinically insignificant as they do not affect perfusion pressure or flow.