To date there is no standardized SpO2 interval, universally recognized as excellent by the scientific community, to guarantee tissue oxygenation in the NICU setting. Multicenter, randomized and large-scale clinical trials have shown SpO2 below 90%, during intensive care stay, are associated with a higher mortality, and saturation values higher than 95% are associated with increased morbidity [11, 12, 22]. The present study allowed to draw a representative picture of how the management of oxygen monitoring is performed in 93 neonatal intensive care units in Italy and which factors independently favored/refrained the use of the recommended targets. The study revealed a wide variability in the utilized ranges for the surveillance of critically ill patients. Failure to comply with the upper and lower limits inevitably exposes the baby to either hypoxia or hyperoxia. Our study showed that in 64.4% of the centers the lower limit of SpO2 is set below 90%, highlighting a propensity to tolerate hypoxia; in contrast, in 24.4% of the centers the upper limit of SpO2 is set above 95% reflecting a permissive attitude towards hyperoxia. In newborns hyperoxia leads to persistent inflammation with impaired innate immune response and increased airway reactivity and susceptibility to respiratory virus infections in adulthood [23]. To limits the dangerous effects of hypoxia or hyperoxia a strict control of oxygen administration is mandatory.
A recent paper investigating the signal type of alarms in the NICU, reported that over 60% of alarms were related to oxygenation monitoring; thus, these represent the major burden of all alarms in newborns population [24]. In this survey, the setting of the maximum value is influenced by the presence or absence of both written operational procedures and staff training, with attention to hyperoxia conditions. NICUs that are particularly sensitive to staff training on the monitoring of SpO2, choose more frequently not to disable the alarms during care maneuvers, compared to the centers with opposite attitude. In this way the risk of missing clinically relevant alarms is reduced. So, it is clear how scientific updating and the active involvement of the trained staff in guiding daily clinical decisions play a decisive role in the quality of patient care. In this context, the so called “alarm fatigue” or alarm desensitization is also a key factor. In the NICU environment, the number of alarm signals may reach several hundred per day determining a huge alarm burden with the effect of staff desensitization, disabling of alarm signals and missing upper alarms [25]. The high rates of false or nonactionable alarms may also be involved. In most cases, nurses/neonatologists can adjust the SpO2 alarm limits and that is reasonable to individualize care to specific patients. However, the presence of local standard protocols may be desirable to avoid individual operator changes to alarm settings. The optimal SpO2 range for the newborn is also a dynamic value that can change (minimum, maximum or both) in relation to comorbidity, the inspired fraction of oxygen, the gestational age of the newborn and the corrected age. In 18.7% of the centers, saturation limits were never changed. This data challenge current recommendation to increase the saturation target to> 95% in those newborns who, at 32 weeks of correct gestational age, still need oxygen supplementation or to reconsider saturation targets in babies with pulmonary hypertension [26, 27]. All these aspects are fundamental not only to guarantee optimal neonatal care but also for later follow-up assessment. The use of specific local protocols and ad hoc personnel training were independently associated with the use of recommended targets limits, indicating the use of these tools as a good local guideline for better neonatal care. A recent European survey, performed only one year before the one presented in this paper, reported a wide variability in ranges similar to our data [21]. Consistently with their findings, the present survey also highlighted a lack of consensus regarding SpO2 target limits for preterm infants. However, they did not take into account the nurses/infants ratio and the “alarm fatigue” and it was not clear if there was a tendency to tolerate hypoxia or a permissive attitude towards hyperoxia, as suggested by the present findings. Moreover, we could not draw conclusions regarding the changes in the neonatologists’ view on SpO2 monitoring since we did not take into account in our survey when the written internal protocol was eventually introduced.
Limitations
The present study has some limitations. First, the questionnaire gives an instant picture of only 25% of the Italian centers. Unfortunately, we were only allowed to send a single reminder to the invited responders. This means that the present study gives only a partial view on the actual situation of SpO2 targets in the Italian NICUs. Furthermore, the absence of more detailed background information on the specific SpO2 monitoring protocols used in each individual institution, and above all the lacking information of clinical outcome limits further conclusions. Also, the absence of a standard local protocol cannot be automatically equated with the absence of knowledge on current guidelines or lower quality of patient care. However, the presence of ad hoc protocols was identified as one of the independent factors associated with the use of recommended SpO2 targets.