Mean Arterial Pressure in Concordant and Discordant Triplets during the First Week of Life

Abstract

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