Maternal pulse pressure at admission is a risk factor for fetal heart rate changes after initial dosing of a labor epidural: a retrospective cohort study

Labor risk factors for fetal heart rate abnormality after combined spinal-epidural analgesia

OBJECTIVE

To explore the association between obstetric factors or outcomes and fetal heart rate (FHR) abnormalities after combined spinal-epidural analgesia (CSEA).

METHODS

Women with singleton term deliveries who received CSEA at our institution between January 1 and December 31, 2017, were analyzed using medical records. We performed a logistic regression analysis to compare factors and outcomes between cases with and without new FHR abnormalities within 1 h after CSEA.

RESULTS

Of the 393 women, 163 showed the new occurrence of FHR abnormality after CSEA. Rupture of the membrane (odds ratio [OR] 2.49; 95% confidence interval [CI] 1.52-4.09; P < 0.01) and dilatation of the cervix (OR 1.24; 95% CI 1.07-1.44; P < 0.01) were significantly associated with FHR abnormalities. There were significant differences in FHR abnormality rates between women with cervical dilatation of 2 cm or less and 3 cm or more (OR 2.20; 95% CI 1.01-4.81; P = 0.047) and 6 cm or less and 7 cm or more (OR 2.46; 95% CI 1.01-6.01; P = 0.048). FHR abnormalities were not significantly associated with cesarean delivery during labor, instrumental delivery, APGAR score below 7 at 1 or 5 min, or umbilical arterial blood gas pH less than 7.2.

CONCLUSION

Rupture of the membrane and an advanced dilated cervix were risk factors for FHR abnormality when CSEA was initiated.

Maternal heart rate variability patterns associated with maternal hypotension and non-reassuring fetal heart rate patterns following initiation of combined spinal-epidural labor analgesia: a prospective observational trial

BACKGROUND

We evaluated whether baseline maternal heart rate variability (HRV), including the Analgesia Nociception Index (ANI), is associated with maternal hypotension and fetal heart rate (FHR) abnormalities following combined spinal-epidural (CSE) labor analgesia.

METHODS

Laboring women were enrolled in this prospective observational study. The primary endpoint was maternal hypotension. The secondary endpoint was FHR abnormalities within 30 min following CSE analgesia initiated with intrathecal plain bupivacaine 1.0 mg and fentanyl 20 µg. The maternal ANI, electrocardiogram, blood pressure, heart rate, oxygen saturation, and FHR tracings were recorded 15 min before and 30 min after CSE. Parturients were grouped based on presence of hypotension and FHR abnormalities. Patient demographics and HRV metrics were compared. Receiver operating characteristics (ROC) curves were constructed for the prediction of hypotension and FHR abnormalities.

RESULTS

No significant intergroup differences were detected in patient characteristics. Several baseline HRV metrics and ANI differed significantly between the normotensive (n = 50) and hypotensive (n = 31) groups and between parturients showing FHR abnormalities (n = 19) and those showing reassuring FHR traces (n = 62). The area under the ROC curve (AUC) for predicting hypotension of the baseline low-frequency (LF)/high-frequency (HF) ratio was 0.677 (95% CI 0.55 to 0.80), and that of the ANI was 0.858 (95% CI 0.78 to 0.94). For predicting non-reassuring FHR patterns, the AUC of the LF/HF ratio was 0.77 (95% CI 0.65 to 0.89), and that of the ANI was 0.833 (95% CI 0.72 to 0.94).

CONCLUSIONS

The ANI can predict the propensity for maternal hypotension and non-reassuring FHR patterns following CSE.

Pulse pressure as a predictor of response to treatment for severe hypertension in pregnancy

BACKGROUND

Pulse pressure is a proposed means of tailoring antihypertensive therapy for treatment of acute-onset, severe hypertension in pregnancy.

OBJECTIVE

This study aimed to determine whether pulse pressure predicts response to the various first-line antihypertensive medications.

STUDY DESIGN

This is a retrospective cohort study from a single academic tertiary care center between 2015 and 2018. Patients were screened for inclusion if they had severe hypertension (defined as systolic blood pressure of ≥160 mm Hg or diastolic blood pressure of ≥110 mm Hg) lasting at least 15 minutes and were initially treated with intravenous labetalol, intravenous hydralazine, or immediate-release oral nifedipine. If a patient had multiple episodes of acute treatment during the pregnancy, only one episode was included in the analysis. The primary outcome was time to resolution (in minutes) of severe hypertension. To adjust for factors that may have affected time to resolution, we first compared baseline characteristics on the basis of the antihypertensive agent received. We then assessed the association between baseline characteristics and resolution of severe hypertension within 60 minutes of treatment. Regression analysis incorporated pulse pressure and antihypertensive agents into a model to predict resolution within 60 minutes of onset of severe hypertension.

RESULTS

A total of 479 women hospitalized with severe maternal hypertension met the inclusion criteria. Hydralazine was the initial antihypertensive agent administered to 113 women, whereas 233 received labetalol, and 133 received nifedipine. Those who initially received nifedipine had a shorter mean time to resolution of severe hypertension (32.6 minutes vs 46.3 for hydralazine and 50.3 for labetalol; P<.01) and were more likely to have resolution of severe hypertension within 60 minutes (91.0% vs 77.9% for hydralazine and 76.8% for labetalol; P<.01). Nifedipine also resulted in a lower mean posttreatment blood pressure. Regression analysis revealed that a lack of resolution of severe hypertension within 60 minutes was independently associated with 2 measures of hypertension severity (mean arterial pressure of ≥125 mm Hg and the need for ≥2 doses of medication) and pulse pressure of >75 mm Hg at the time of treatment, initial treatment with labetalol, and gestational age of <37 weeks at the time of the hypertensive event (or at delivery if treatment was after delivery). The model's bias-corrected bootstrapped area under the receiver operating characteristic curve was 0.85 (95% confidence interval, 0.79-0.88). Interaction terms between pulse pressure and each antihypertensive agent were not significant and therefore not incorporated into the final model.

CONCLUSION

Pulse pressure did not predict response to the various first-line antihypertensive agents. Initial treatment with oral nifedipine was associated with a higher likelihood of resolution of severe hypertension within 60 minutes of treatment than with intravenous labetalol.

Contraction-Associated Maternal Heart Rate Decelerations: A Pragmatic Marker of Intrapartum Volume Status

OBJECTIVE

To define and characterize a maternal contraction-associated heart rate deceleration pattern and evaluate its association with maternal volume status.

METHODS

We performed a prespecified secondary analysis of a prospectively collected cohort from a randomized controlled trial of maternal pulse pressure, epidural coload volume, and postepidural complications. Participants were healthy intrapartum women with nonanomalous singleton gestations at 35 weeks of gestation or greater and a category 1 fetal heart rate (FHR) pattern from admission to epidural placement. Those lacking continuous maternal pulse oximetry data before epidural placement were excluded. Maternal heart rate tracings were evaluated for the presence of a contraction-associated heart rate deceleration pattern before epidural placement. Women with and without a contraction-associated heart rate deceleration pattern were compared using univariable and multivariable analyses. The primary outcome was the frequency of a contraction-associated heart rate deceleration pattern in hypovolemic compared with euvolemic women as defined by admission pulse pressure (less than 45 and 50 mm Hg or greater, respectively). Secondary outcomes included the association of a contraction-associated heart rate deceleration pattern with postepidural complications related to maternal volume status including new-onset category 2 and 3 FHR abnormalities, maternal hypotension, and the need for resuscitative obstetric interventions.

RESULTS

Of 414 trial participants, 388 (93.7%) met inclusion criteria, and 124 of these (32.0%) had a contraction-associated heart rate deceleration pattern before epidural placement. The presence of a contraction-associated heart rate deceleration pattern was more frequent among hypovolemic compared with euvolemic women as defined by admission pulse pressure (41.1% vs 13.6%, relative risk [RR] 3.0, 95% CI 1.9-4.8, P<.001). A contraction-associated heart rate deceleration pattern was associated with more frequent postepidural FHR abnormalities (43.5% vs 31.1%, RR 1.4, 95% CI 1.1-1.8, P=.02), diastolic hypotension (63.7% vs 50.0%, RR 1.3, 95% CI 1.1-1.5, P=.01), and the need for resuscitative interventions (33.9% vs 23.1%, RR 1.5, 95% CI 1.1-2.0, P=.03). In multivariable analysis with adjustment for baseline differences between groups, the associations between a contraction-associated heart rate deceleration pattern and abnormal FHR patterns, diastolic hypotension, and the need for resuscitative interventions persisted and were slightly strengthened.

CONCLUSION

The maternal contraction-associated heart rate deceleration pattern is a pragmatic, bedside visual indicator of intrapartum maternal volume status. A contraction-associated heart rate deceleration pattern is threefold more frequent among hypovolemic compared with euvolemic women as defined by admission pulse pressure and is associated with postepidural complications including abnormal FHR patterns, diastolic hypotension, and the need for resuscitative interventions. The contraction-associated heart rate deceleration pattern highlights a novel role for intrapartum maternal heart rate assessment and may inform the individualization of intrapartum fluid management.

Pulse Pressure and Carotid Artery Doppler Velocimetry as Indicators of Maternal Volume Status: A Prospective Cohort Study

BACKGROUND

Narrow pulse pressure has been demonstrated to indicate low central volume status. In critically ill patients, volume status can be qualitatively evaluated using Doppler velocimetry to assess hemodynamic changes in the carotid artery in response to autotransfusion with passive leg raise (PLR). Neither parameter has been prospectively evaluated in an obstetric population. The objective of this study was to determine if pulse pressure could predict the response to autotransfusion using carotid artery Doppler in healthy intrapartum women. We hypothesized that the carotid artery Doppler response to PLR would be greater in women with a narrow pulse pressure, indicating relative hypovolemia.

METHODS

Intrapartum women with singleton gestations ≥35 weeks without acute or chronic medical conditions were recruited to this prospective cohort study. Participants were grouped by admission pulse pressure as <45 mm Hg (narrow) or ≥50 mm Hg (normal). Maternal carotid artery Doppler assessment was then performed in all patients before and after PLR using a standard technique where carotid blood flow (mL/min) = π × (carotid artery diameter/2) × (velocity time integral) × (60 seconds). The velocity time integral was calculated from the Doppler waveform. The primary outcome was the change in the carotid Doppler parameters (carotid artery diameter, velocity time integral, and carotid blood flow) after PLR. Outcomes were compared between study groups with univariable and multivariable analyses with adjustment for potential confounding factors.

RESULTS

Thirty-three women consented to participation, including 18 in the narrow and 15 in the normal pulse pressure groups (mean and standard deviation initial pulse pressure, 38.3 ± 4.4 vs 57.3 ± 4.1 mm Hg). The 2 groups demonstrated similar characteristics except for initial pulse pressure, systolic and diastolic blood pressure, and race. In response to PLR, the narrow pulse pressure group had a significantly greater increase in carotid artery diameter (0.08 vs 0.02 cm; standardized difference, 2.0; 95% confidence interval [CI], 1.16-2.84), carotid blood flow (79.4 vs 16.0 mL/min; standardized difference, 2.23; 95% CI, 1.36-3.10), and percent change in carotid blood flow (47.5% vs 8.7%; standardized difference, 2.52; 95% CI, 1.60-3.43) compared with the normal pulse pressure group. In multivariable analysis with adjustment for potential confounding factors, women with narrow admission pulse pressure had a significantly larger carotid diameter (0.66 vs 0.62 cm; P < .0001) and greater carotid flow (246.7 vs 219.3 cm/s; P = .001) after PLR compared to women with a normal pulse pressure. Initial pulse pressure was strongly correlated with the change in carotid flow after PLR (r = 0.60; P < .0001).

CONCLUSIONS

The hemodynamic response of the carotid artery to autotransfusion after PLR is significantly greater in women with narrow pulse pressure. Pulse pressure correlates with the physiological response to autotransfusion and provides a qualitative indication of intravascular volume in term and near-term pregnant women.