Carbon dioxide and retinopathy of prematurity in extremely low birth weight infants.

Objective

To evaluate the relationship between partial pressure of carbon dioxide (PCO2) during the first 3 days of life and retinopathy of prematurity (ROP) in extremely low birthweight (ELBW) infants.Patients and methods: A retrospective evaluation of data on ELBW infants were collected over a period of 4 years. Data during the first 72 hours of life was divided into six, 12-hour epochs. The average highest and overall means of PCO2, PO2, FiO2, and glucose were calculated for each epoch. Logistic regression analysis was used to determine the association between PCO2 and ROP after controlling for covariables.

Results

A total of 78 neonates were included: birth weight (BW) (703 ± 157 g) and gestational age (25 ± 1.4 weeks). A total of 45 out of 78 had ROP: stage 1 (N = 8), stage 2 (N = 26), stage 3 (N = 14), and plus (N = 4). The overall mean PCO2 correlated with ROP in the first 72 hours of life (R = 0.31, p = .0069). This correlation was significant in epochs 2 (p = .049), 4 (p = .008) and 6 (p = .038). The average of the highest PCO2 also correlated with ROP in the first 72 hours of life (R = 0.38, p = .0007). This correlation was significant in epochs 2 (p = .0115), 4 (p = .0011), 5 (p = .028) and 6 (p = .037). The correlation between the stage of ROP and PCO2 was significant after controlling for PO2 and glucose concentrations. Other variables that correlated with ROP were the overall means of FiO2 (R = 0.23, p = .04), PO2 (R = 0.39, p = .0005) and glucose (R = 0.39, p = .0004) as well as the average highest concentrations of FiO2 (R = 0.26, p = .025), PO2 (R = 0.38, p = .0008) and glucose (R = 0.34, p = .007).

Conclusion

After controlling for confounding variables, ROP correlated with the overall means and average highest PCO2. ROP also correlated with FiO2, PO2 and glucose concentrations. Further studies are needed to define the safe PCO2 range and the effect of PCO2 on the normal development of the retina.