Maintaining optimal oxygen saturation in premature infants

Abstract

Introduction: Advances in technology have resulted in increasing survival rates for premature infants. Oxygen therapy is commonly used in neonatal units as part of respiratory support. The number of premature infants in our institution surviving with severe (stage ≥3) retinopathy of prematurity (ROP) prompted a review of oxygen therapy as a contributing factor. Prolonged exposure to high concentrations of oxygen may cause irreversible damage to the eyes of very-low-birth-weight preterm infants and is a potential cause of blindness.

Objective: We developed strategies to reduce incidence of severe ROP requiring laser surgery in premature infants.

Methods: We studied 37 preterm infants who were born at a gestational age of <32 weeks, with a birth weight of <1500 g, receiving supplemental oxygen, and had been admitted to our neonatal intensive care unit. Infants received oxygen via mechanical ventilator, nasal continuous positive airway pressure (CPAP), or intranasal (I/N) and titration of oxygen was based on each infant's measured oxygen saturation (Spo(2)). For each infant, we monitored the Spo(2) trend, Spo(2) alarm limit, and the percentage of time that the alarm limit was set incorrectly. We implemented a Spo(2) targeting protocol and developed an algorithm for titrating fraction of inspired oxygen (Fio(2)).

Results: After phase 1 of implementation, the percentage of time that Spo(2) readings were >95% was reduced to between 20% and 50%. However, our findings raised concern regarding the wide fluctuation of Spo(2) readings because of inconsistency in Fio(2) titration, which can contribute to deviation from the optimal target range. Accordingly, we developed an algorithm for titrating Fio(2) aimed at maintaining each infant's Spo(2) within the optimal target range. After phase 2 of implementation, the percentage of Spo(2) readings >95% was markedly reduced to between 0% and 15%. The incidence of infants with severe ROP requiring laser surgery decreased from 5 to 1.

Conclusions: A change in clinical practice aimed at maintaining oxygen within the target range to avoid a high Spo(2) was associated with a significant decrease in the incidence of both severe ROP and the need for laser surgery, thus reducing hospital costs and length of hospital stays for premature infants.

Figure 1

Distribution of retinopathy of prematurity (ROP) cases in our study according to disease stage.

Figure 2

Percentage of time premature infants with oxygen saturation (Spο₂) values >95% during March 2008. Horizontal line represents Mean.

Figure 3

Cause and effect for hypoxia and hyperoxia in hospitalized preterm infants. Fιο₂ = fraction of inspired oxygen; ICU = intensive care unit; Spο₂ = oxygen saturation.

Figure 4

Root causes of hypoxia and hyperoxia in hospitalized preterm infants, based on the survey responses of the neonatology staff. Fιο₂ = fraction of inspired oxygen, Spο₂ = oxygen saturation.

Figure 5

Algorithm for oxygen titration. Fιο₂ = fraction of inspired oxygen; NICU = neonatal intensive care unit; Spο₂ = oxygen saturation.

Figure 6

Algorithm for Fιο₂ titration to manage the high and low oxygen saturation (Spο₂) in premature infants. CPAP = continuous positive airway pressure; Fιο₂ = fraction of inspired oxygen; I/N = intranasal.

Figure 7

Percentage of time premature infants' oxygen saturation (Spο₂) values that were higher than target range before, during, and after implementation (from March to September 2008). Horizontal line represents Mean.

Figure 8

Comparison of the number of premature infants with severe retinopathy of prematurity (stage 3 or 4) requiring laser surgery before and after a two-phase intervention.