Systematic underestimation of oxygen delivery in ventilated preterm infants.
BACKGROUND
Emerging evidence indicates that hyperoxia is a risk factor for bronchopulmonary dysplasia, a common multifactorial long-term complication of prematurity. To date, the equivalence between set and delivered oxygen (O(2)) in ventilated preterm infants has not been rigorously studied.


OBJECTIVE
To test the hypothesis of systematic underestimation of O(2) delivery in extremely low birth weight (ELBW) infants during long-term ventilation.


METHODS
Actually achieved O(2) concentrations were measured and compared to the set inspired oxygen fraction (FiO(2)). A total of 108 O(2) measurements were carried out during the ventilation of 54 ELBW infants: O(2)-Delta error (i.e., the difference between O(2) concentrations achieved by the ventilator and set FiO(2)) was the main study outcome measure.


RESULTS
Systematic O(2)-Delta errors were found, with mean values of +9.52% (FiO(2) 0.21-0.40), +2.10 (FiO(2) 0.41-0.60), +2.86% (FiO(2) 0.61-0.80), and +0.016% (FiO(2) 0.81-1.0; p < 0.0001). Theoretical simulations from the observed data indicate that, if not corrected, systematic O2-Delta errors would lead to a non-intentional total O(2) load of 1,202.9 (FiO(2) 0.21-0.40), 252.46 (FiO(2) 0.41-0.60), 342.85 (FiO(2) 0.61-0.80), and 2 (FiO(2) 0.81-1.0) extra liters/kg body weight/100 ventilation hours.


CONCLUSIONS
Systematic underestimation of the O(2) delivered by infant ventilators can potentially lead to surprisingly large increases in total O(2) load during long-term ventilation of ELBW infants, especially in the lower FiO(2) range (i.e., 0.21-0.40). Underestimation of true O(2) delivery can potentially lead to unrecognized high O(2) loads, and more pronounced and prolonged hyperoxia.
De Felice
Claudio
C
Neonatal Intensive Care Unit, Policlinico S. Maria alle Scotte, Azienda Ospedaliera Universitaria Senese, Siena, Italy. claudiodefelix @ hotmail.it
Bechelli
Stefano
S
Tonni
Gabriele
G
Latini
Giuseppe
G
Hansmann
Georg
G
D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000097:blood* / Q000209:etiology*; D007223:Infant; D052577:Infant, Extremely Low Birth Weight / Q000097:blood*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008297:Male; D018384:Oxidative Stress; D010100:Oxygen / Q000097:blood*; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects; D012121:Respiration, Artificial / Q000009:adverse effects*
D010100:Oxygen