Tidal Volume Requirement in Mechanically Ventilated Infants with Meconium Aspiration Syndrome.

OBJECTIVE: The aim of the study is to test the hypothesis that increased physiologic dead space and functional residual capacity seen in meconium aspiration syndrome (MAS) results in higher tidal volume (VT) requirement to achieve adequate ventilation.

STUDY DESIGN: Retrospective review of infants with MAS admitted to our hospital from 2000 to 2010 managed with conventional ventilation. Demographics, ventilator settings, VT, respiratory rate (RR), and blood gas values were recorded. Minute ventilation (MV) was calculated as RR × VT. Only VT values with corresponding partial pressure of carbon dioxide (Paco 2) between 35 and 60 mm Hg were included. Mean VT/kg and MV/kg were calculated for each patient. Forty infants ventilated for lung disease other than MAS or pulmonary hypoplasia served as controls.

RESULTS: Birth weights of the 28 MAS patients and 40 control infants were similar (3,330 ± 500 g and 3,300 ± 640 g). Two patients in each group required extracorporeal membrane oxygenation. Infants with MAS required 26% higher VT and 42% higher MV compared with controls to maintain equal Paco 2.

CONCLUSION: Infants with MAS require larger VT and higher total MV to achieve similar alveolar ventilation, consistent with pathophysiology of MAS. Our findings provide the first reference data to guide selection of VT in infants with MAS.