243 Changes in Gas Exchange and Oxygenation During Surfactant Administration Using Continuous Arterial Blood Gas Monitoring

Abstract

Background: While prophylactic surfactant is an evidence based treatment for infants less than 28 weeks gestation, problems occuring during administration including changes in arterial partial pressure of oxygen and carbondioxide (PaO2 & PaCO2) and drug reflux through endotracheal tube (ETT) have been reported. The volume of a surfactant is relevant to the ease of administration and acceptability to the neonatal lungs. In our experience, surfactants with larger volume can cause hypercarbia and hypoxia associated with ETT obstruction, more frequently with high frequency oscillatory ventilation (HFOV), requiring prolonged intermittent positive pressure ventilation (IPPV) immediately after administration. Curosurf volume (100mg/1.25ml/kg) is considerably smaller than other surfactants (100mg/3–4ml/kg) and administered as a single dose. Larger volumes with fractional doses do not give same enhancement on gas exchange as same total dose given by a single dose. Continuous blood gas monitoring (CBGM) has been proven to provide continuous records of changes in pH, PaO2 & PaCO2 with acceptable precision compared to standard blood gas measurements.Aims: To stydy the changes in pH, PaCO2 & PaO2 during surfactant (Curosurf) administration using CBGM.Methods: Pretrem infants less than 28 weeks with respiratory distress syndrome requiring HFOV who had a multi-parameter intraarterial sensor, placed in an umbilical arterial catheter were studied prospectively. Changes were recorded during and 10 minutes after Curosurf administration. The data together with CBGM record printouts are available for discussion.Results: 5 infants (mean gestation 25.8 weeks) were included in the study. All infants tolerated the administration very well with no significant changes in heart rate. In all infants, there were minimal changes in PaCO2 ( mean + 0.18 kPa) 10 minutes after Curosurf. IPPV was applied only for less than 20 seconds and the change in mode of ventilation was not necessary. FiO2 was lower (mean −0.12) with changes in PaO2 (mean − 0.7 kPa) in 10 minutes after Curosurf.Conclusions: This small but important study provides information on effects of Curosurf while it is being given, proven by CBGM. Minimal changes in PaCO2 and minimal interruption in alveolar recruitment on HFOV while surfactant is administered are important in extremely preterm infants' ventilatory management and cerebral circulation. Further studies in these areas with larger number of infants are indicated.