Mean arterial pressure in extremely low birth weight concordant and discordant twins during the first day of life

Postnatal blood pressure in the preterm small for gestational age neonate

OBJECTIVE

Determine how blood pressure differs in premature infants born small for gestational age (SGA).

DESIGN

A retrospective study was conducted on inborn infants 24-32 weeks gestation. Mean arterial blood pressure (MAP) was collected and averaged every 12 h for the first 96 h of life. For each time point, the difference MAP in SGA vs. AGA infants was evaluated with t-testing. Linear mixed-effects modeling was performed to model MAP over time accounting for GA, BW, gender, and SGA status.

RESULTS

356 subjects were evaluated. 52 (14.6%) were SGA. SGA infants were smaller, more likely male, exposed to maternal hypertension, born via caesarian section, and have chronic lung disease and retinopathy of prematurity. MAP in the SGA group more closely matched the MAP of AGA babies of similar GA for the first 24 h of life. Subsequently, SGA infants had lower MAPs more closely resembling their weight-matched counterparts. Mixed modeling showed GA to be significant, p < 0.0001 while BW though still marginally significant had less of an effect, p = 0.049.

CONCLUSION

SGA infants have blood pressure that is strongly associated with GA in the first 24 hours of life, but then fails to increase at the same rate as their AGA counterparts.

Early neonatal hypotension in premature infants born to preeclamptic mothers

BACKGROUND

Early neonatal hypotension (ENH) is common in premature infants and has been claimed to occur more frequently in infants born to mothers with severe preeclampsia. Previous studies that showed a relationship between maternal preeclampsia and neonatal hypotension did not control for potential confounding factors such as birth weight and maternal treatment with magnesium sulfate (MgSO4).

OBJECTIVE

To determine whether maternal preeclampsia is an independent risk factor for ENH.

STUDY DESIGN

We conducted a retrospective review of all viable singleton infants with gestational age of 23 to 30 weeks who were admitted to the neonatal intensive care unit over a 2-year period. ENH was defined as the persistence of the mean arterial pressure lower than the gestational age in weeks requiring volume expansion and inotropic support in the first 24 h of life.

RESULTS

One hundred and eighty four infants were enrolled. Seventy-five (41%) infants met the diagnostic criteria for ENH. Maternal preeclampsia, the presence of labor, maternal treatment with MgSO4, Apgar scores, birth weight, gestational age and respiratory distress syndrome were significantly associated with ENH by univariate analysis. Only gestational age and maternal preeclampsia were significantly associated with ENH by multiple logistic regression.

CONCLUSION

Gestational age and maternal preeclampsia were independent risk factors for ENH in our population of premature infants.

Mean arterial pressure in concordant and discordant triplets during the first week of life

OBJECTIVE

To retrospectively determine mean arterial pressure (MAP) for stable concordant and discordant triplets during the first 7 days of life.

BACKGROUND

Morbidity and mortality for prematurely born triplets is high, therefore, MAP monitoring during the first day of life is important for their clinical management. MAP reference values for special populations such as triplets have not been published. Recently, we reported that in stable discordant twins MAP values during the first day of life were significantly lower in the smaller than in their larger siblings. Comparable information for triplets is not available.

DESIGN

Retrospective cohort study.

METHODS

We studied 30 sets of concordant and 29 sets of discordant (birth weight difference > or =20%) consecutively born triplets. Stable patients were defined as those having umbilical cord hemoglobin > or =13 g/dl, normal blood gases, who were never treated for hypotension, and survived at least 7 days. MAP (torr) were measured by oscillometry in 3410, and by transducer via an umbilical arterial catheter in 1251 instances.

RESULTS

Concordant and discordant triplets were similar in demographics, history of preterm labor (63 and 63%), chorioamnionitis (10 and 10%), pre-eclampsia (53 and 48%), cesarean delivery (100 and 100%), antenatal steroids (77 and 73%), cord hemoglobin (16 and 16 g/dl), combined triplets birth weight (4922 and 4732 g), gestational age (32 and 33 weeks), normal head ultrasounds or Grade I intracranial hemorrhage (96 and 100%) and neonatal mortality (2 and 1%), but were different in the number of infants requiring mechanical ventilation (57 and 31%). A total of 80 (89%) concordant triplets and 77 (88%) discordant triplets were stable according to our definition. Concordant stable triplets, whether small, medium or large, had similar MAP at birth. Their MAP values increased noticeably from birth to 24 hours and more subtlely to 7 days. Triplets of < or =32 weeks GA had lower MAP throughout than those of > or =33 weeks GA. Discordant stable triplets were divided into 27 small (1382 g), 26 medium (1683 g) and 27 large (1969 g); during the first 24 hours, medium and smaller triplets had MAP values that were lower than those of their larger siblings. From the second to the seventh day of life, all MAP values and trends were similar. Among discordant triplets, 86% of the smallest, 13% of the medium and 13% of the largest infants had asymmetrical intrauterine growth restriction.

CONCLUSION

In stable concordant and stable discordant triplets, MAP correlates with birth weight, gestational age and postnatal age. MAP values increase noticeably during the first 24 hours and more subtlely during the next 7 days. Concordant or discordant, small, medium, and large triplets have similar MAP values and trends to that of their siblings. Small and medium discordant triplets have lower MAP values during the first day of life than their larger siblings but by the second day there MAP trends and values were no longer different.

Mean arterial pressure in very low birth weight (801 to 1500 g) concordant and discordant twins during the first day of life

OBJECTIVE

To determine retrospectively mean arterial pressure (MAP) for stable and unstable concordant and discordant very low birth weight (VLBW: 801 to 1500 g) twins during the first 24 hours of life.

BACKGROUND

Morbidity and mortality are much higher for extremely low birth weight (ELBW < or =800 g) than for VLBW twins. Recently, we reported MAP trends and reference values in concordant and discordant ELBW twins. No comparable information is available for VLBW infants.

DESIGN

Retrospective cohort study.

METHODS

We studied 48 sets of concordant and 40 sets of discordant (birth weight difference > or =20%) consecutively born VLBW twins. Stable patients were defined as having umbilical cord hemoglobin > or =14 g/dl, nonacidotic blood gases, never treated for hypotension and survived at least 7 days. MAPs (Torr) were measured by oscillometry in 3163 and by transducer via umbilical artery in 2028 instances.

RESULTS

Concordant and discordant twins were similar in demographics, history of twin-twin transfusion (TTTX), antenatal steroids, chorioamnionitis, pre-eclampsia, cesarean delivery, cord hemoglobin, normal head ultrasounds or I to II intracranial hemorrhage (97 and 99%) and neonatal mortality (4 and 5%), but were different in incidence of preterm labor (83 and 58%), birth weight (1227 and 1509 g) and gestational age (GA) (30 and 32 weeks). In all, 66 (69%) concordant twins and 61 (76%) discordant twins were stable. Stable concordant twins, whether small or large, had comparable MAP on admission that increased to 24 hours. Twins of < or =32 weeks GA had lower MAP throughout than those of > or =33 weeks GA. Although their mean birth weights were similar (1262 and 1274 g), 23 stable concordant males had significantly higher MAP than 43 concordant females. Stable discordant twins were divided into 31 small (1241 g) and 30 large (1845 g); their MAPs were different (p<0.05): 35 and 39 (admission), 35 and 39 (1 hour), 36 and 46 (6 hours), 38 and 41 (12 hours), 40 and 41 (18 hours) and 42 and 42 (24 hours) Torr. In all, 88% of small discordant twins were IUGR and 91% of large discordant twins had normal growth. TTTX syndrome occurred in 12 monochorionic sets. Nine of 12 donors were IUGR while 10 of 12 recipients had normal growth. Four of 12 donors had grades III to IV intracranial hemorrhage, eight donors and all 12 recipients had normal ultrasounds. Although their cord hemoglobin levels were similar, donor and recipient MAPs were higher than in any other group and, opposite to concordant and discordant twins, their values decreased from birth to 24 hours.

CONCLUSION

In stable concordant, stable discordant, and small and large discordant twins, MAP correlates with birth weight, GA and postnatal age, and increases during the first 24 hours. In recipient and donor twin-twin transfusion infants, MAP is higher throughout and declines over time.