Optimizing Oxygen Saturation Targets in Extremely Preterm Infants

Monitoring SpO2: The Basics of Retinopathy of Prematurity (Back to Basics) and Targeting Oxygen Saturation

Oxygen (O2) is a drug frequently used in newborn care. Adverse effects of hypoxia are well known but the damaging effects of excess oxygen administration and oxidative stress have only been studied in the last 2 decades. Many negative effects have been described, including retinopathy of prematurity . Noninvasive pulse oximetry (SpO2) is useful to detect hypoxemia but requires careful evaluation and understanding of the frequently changing relationship between O2 and hemoglobin to prevent hyperoxemia. Intention to treat SpO2 ranges should be individualized for every newborn receiving supplemental O2, according to gestational age, post-natal age, and clinical condition.

Evaluating enhanced pulse oximetry auditory displays for neonatal oxygen targeting: A randomized laboratory trial with clinicians and non-clinicians

Standard pulse oximeter auditory tones do not clearly indicate departures from the target range of oxygen saturation (SpO₂) of 90%-95% in preterm neonates. We tested whether acoustically enhanced tones would improve participants' ability to identify SpO₂ range. Twenty-one clinicians and 23 non-clinicians used (1) standard pulse oximetry variable-pitch tones plus alarms; (2) beacon-enhanced tones without alarms in which reference tones were inserted before standard pulse tones when SpO₂ was outside target range; and (3) tremolo-enhanced tones without alarms in which pulse tones were modified with tremolo when SpO₂ was outside target range. For clinicians, range identification accuracies (mean (SD)) in the standard, beacon, and tremolo conditions were 52% (16%), 73% (14%) and 76% (13%) respectively, and for non-clinicians 49% (16%), 76% (13%) and 72% (14%) respectively, with enhanced conditions always significantly more accurate than standard. Acoustic enhancements to pulse oximetry clearly indicate departures from preterm neonates' target SpO₂ range.

Uncertainty Estimation of Biomedical Oximeters: Proposal for an Experimental Test-Bench

Paramagnetic oximeters are frequently used in clinical practice to measure and titrate the fraction of inspired oxygen (FiO2) administered to a hypoxic patient. Newborns are prone to several diseases leading to hypoxia but also to oxidative damage, therefore a precise measurement of administered oxygen is of paramount importance. In this study, we evaluated and compared the performance of four commonly used gas analyzers at a Neonatal Unit. A paramagnetic gas analyzer was considered the standard for reference. Gas mixing performed by blenders was also evaluated. We first assessed the stability and composition of O2 and medical air. A settling time study was conducted to estimate a steady-state. Results show how tested blenders underestimated the real measures when FiO2 was <50% and overestimated them when FiO2 ≥50%. In all the tested oximeters the FiO2 was underestimated by 1.18%, but the overall agreement with the gold standard was very good.

Management of oxygen saturation monitoring in preterm newborns in the NICU: the Italian picture

Background

Although many studies emphasize the importance of using oxygen saturation (SpO₂) targets in the NICUs, there is a wide variability in used saturation ranges among centers. Primary aim was to draw a representative picture on how the management of oxygen monitoring is performed in the Italian NICUs. Second aim was to identify healthcare-professionals related factors associated with oxygen targeting in the preterm population.

Methods

Cross-sectional study with data collection via an electronic survey form. A questionnaire containing pre-piloted and open questions on monitoring and management of the SpO₂ was administered to neonatologists across the network of the Italian Society of Neonatology. The questions focused on: the infrastructure, specific training, healthcare professionals and patients-related factors. The results of the survey were anonymously collected, summarized and analyzed.

Results

Out of 378 questionnaires, 93 were correctly filled. Thirty-six different SpO₂ ranges were observed. Centers using written standard operating procedures on oxygen management and SpO₂ monitoring maintained a correct average range of SpO₂ 90–95%, avoided hyperoxia and reconsidered saturation targets in relation to comorbidities. 39.8% of responders disabled alarms during neonatal care. One center used biomarkers for complete monitoring of neonatal oxygenation status.

Conclusions

There is considerable variation in SpO₂ targets for preterm infants in the Italian NICUs. Standard operating procedures and specific training for health care personnel are the main factors playing a role for the correct maintenance of the recommended oxygen targets in preterms.

Benefits and obstacles to cell therapy in neonates: The INCuBAToR (Innovative Neonatal Cellular Therapy for Bronchopulmonary Dysplasia: Accelerating Translation of Research)

Cell-based therapies hold promise to substantially curb complications from extreme preterm birth, the main cause of death in children below the age of 5 years. Exciting preclinical studies in experimental neonatal lung injury have provided the impetus for the initiation of early phase clinical trials in extreme preterm infants at risk of developing bronchopulmonary dysplasia. Clinical translation of promising therapies, however, is slow and often fails. In the adult population, results of clinical trials so far have not matched the enticing preclinical data. The neonatal field has experienced many hard-earned lessons with the implementation of oxygen therapy or postnatal steroids. Here we briefly summarize the preclinical data that have permitted the initiation of early phase clinical trials of cell-based therapies in extreme preterm infants and describe the INCuBAToR concept (Innovative Neonatal Cellular Therapy for Bronchopulmonary Dysplasia: Accelerating Translation of Research), an evidence-based approach to mitigate the risk of translating advanced therapies into this vulnerable patient population. The INCuBAToR addresses several of the shortcomings at the preclinical and the clinical stage that usually contribute to the failure of clinical translation through (a) systematic reviews of preclinical and clinical studies, (b) integrated knowledge transfer through engaging important stakeholders early on, (c) early economic evaluation to determine if a novel therapy is viable, and (d) retrospective and prospective studies to define and test ideal eligibility criteria to optimize clinical trial design. The INCuBAToR concept can be applied to any novel therapy in order to enhance the likelihood of success of clinical translation in a timely, transparent, rigorous, and evidence-based fashion.

Comparison of Biphasic vs Static Oxygen Saturation Targets Among Infants With Retinopathy of Prematurity

Importance

The Surfactant, Positive Pressure, and Pulse Oximetry Randomized Trial (SUPPORT) demonstrated that static low oxygen saturation decreased retinopathy of prematurity (ROP) but increased mortality compared with static high oxygen saturation cohorts.

Objective

To compare outcomes of a biphasic oxygen protocol with static targets recommended by SUPPORT.

Design, Setting, and Participants

Retrospective cohort study comparing biphasic vs static standards 41 months prior to and 42 months after a change from biphasic to static SUPPORT standards at a level III neonatal intensive care unit (Fairview Hospital, Cleveland, Ohio). The study included infants born at a corrected gestational age (CGA) of 31 weeks or younger or birth weight 1500 g or less. Data were analyzed between August 2010 and July 2017.

Interventions

The pre-SUPPORT group underwent biphasic protocol target saturations of 85% to 92% at younger than 34 weeks' CGA and greater than 95% at 34 weeks' CGA or older. The post-SUPPORT group underwent a constant 91% to 95% target.

Main Outcomes and Measures

Primary outcome was incidence of type 1 ROP. Secondary outcomes were incidence of any ROP, time to full vascularization, and mortality.

Results

Of 596 eligible infants, 562 were included in ophthalmic analysis. Three hundred three patients were boys (54%); 399 were white (71%), 87 were black (15%), and 76 were of other or unknown race/ethnicity (14%). Mean (SD) CGA and birth weight were 29 (2) weeks and 1151 (346) g, respectively. Any ROP overall increased (53 [20%] pre-SUPPORT vs n = 86 [28%] post-SUPPORT; absolute difference, 8%; 95% CI, 1%-15%; odds ratio, 1.6; 95% CI, 1.05-2.3; P = .03). Type 1 ROP increased in the post-SUPPORT era (n = 6 [2%] pre-SUPPORT vs n = 18 [6%] post-SUPPORT; absolute difference, 4%; 95% CI, 0.4%-7%; odds ratio, 2.7; 95% CI, 1.05-6.9; P = .03). There was a delay in vascularization in the post-SUPPORT group (n = 6 [2%] pre-SUPPORT vs n = 18 [6%] post-SUPPORT; absolute difference, 4%; 95% CI, 0.4%-7%; P = .03).

Conclusions and Relevance

Compared with static oxygen standards, biphasic oxygen targets are associated with decreased incidence and severity of ROP without increasing mortality.

The impact of preterm adversity on cardiorespiratory function

NEW FINDINGS

What is the topic of this review? We review the influence of prematurity on the cardiorespiratory system and examine the common sequel of alterations in oxygen tension, and immune activation in preterm infants. What advances does it highlight? The review highlights neonatal animal models of intermittent hypoxia, hyperoxia and infection that contribute to our understanding of the effect of stress on neurodevelopment and cardiorespiratory homeostasis. We also focus on some of the important physiological pathways that have a modulatory role on the cardiorespiratory system in early life.

ABSTRACT

Preterm birth is one of the leading causes of neonatal mortality. Babies that survive early-life stress associated with immaturity have significant prevailing short- and long-term morbidities. Oxygen dysregulation in the first few days and weeks after birth is a primary concern as the cardiorespiratory system slowly adjusts to extrauterine life. Infants exposed to rapid alterations in oxygen tension, including exposures to hypoxia and hyperoxia, have altered redox balance and active immune signalling, leading to altered stress responses that impinge on neurodevelopment and cardiorespiratory homeostasis. In this review, we explore the clinical challenges posed by preterm birth, followed by an examination of the literature on animal models of oxygen dysregulation and immune activation in the context of early-life stress.

Dutch Neonatal Intensive Care Nurses' Perceptions of Pulse Oximeter Saturation Target Limits for Preterm Infants

PURPOSE

To conduct a national survey to assess practice, knowledge, barriers, and perceptions regarding oxygen saturation (SpO₂) target limits among Dutch neonatal intensive care unit (NICU) nurses.

DESIGN AND METHODS

Cross-sectional, web-based survey among 667 nurses from 9 level 3 Dutch NICUs. Part of the questions were based on a clinical scenario (28-weeks preterm infant, treated with CPAP, FiO₂ 0.4).

RESULTS

328 (53.6%) nurses responded to the survey. Of these, 281 (85.7%) reported to know the local policy of SpO₂ target limits, and 261 (79.6%) and 244 (74.4%) rightly identified the lower and upper limit, respectively. Six NICUs recently increased their lower SpO₂ limit and for 62.0% of their nurses this led to a significant alarm increase. For the majority of the respondents, the baby from the clinical scenario would spend <10% of the time outside the lower or upper SpO₂ limits. Automated oxygen control systems were considered a good idea by 59.2% of the respondents, but 53.9% considered allowing parents to participate in FiO₂ titration a bad or very bad idea_. CONCLUSIONS: The majority of the respondents identified their unit's policy-specified SpO₂ target limits and reported that the increase in SpO₂ target limits may have led to more alarms. Titration of FiO₂ is a part of care that respondents were reluctant to share with parents.

PRACTICE IMPLICATIONS

A potential increase in the number of SpO₂ alarms may lead to alarm fatigue. Although family-centered care philosophy is widely accepted across Dutch NICUs, there are still barriers to overcome.

Primary prevention of ROP and the oxygen saturation targeting trials

Reducing the burden of visual morbidity from retinopathy of prematurity (ROP) begins with primary prevention, and improvements in neonatal care with a positive impact on ROP are possible in all settings. Strategies range from rigorous adoption of inexpensive evidence-based protocols, for example on temperature control, prevention of sepsis and support for breast-milk feeding, through to comprehensive quality improvement programmes, and fostering team work and camaraderie. Oxygen monitoring is essential for very preterm infants receiving supplementary oxygen. The Neonatal Oxygenation Prospective Meta-analysis (NeOProM) collaboration has reported analysis of five trials of oxygen saturation (SpO₂) targeting in very preterm infants and shown that a SpO₂ target of 85-89% compared to 91-95% was associated with increased mortality (on average 28 extra deaths for every 1000 infants treated). Adopting a SpO₂ target higher than 85-89% might increase the risk of ROP for some infants, highlighting the importance of pursuing all other means of prevention.

Current Recommendations and Practice of Oxygen Therapy in Preterm Infants

This narrative review identified 23 publications in 2011 to 2019 discussing randomized trials of oxygen saturation targets of 85% to 89% versus 91% to 95% in infants below 28 weeks' gestation. Of 18 commentaries or consensus statements, 17 recommended saturation targets above 89%. Five systematic reviews reported that the 85% to 89% target increased mortality but not the composite of death or disability. The evidence for increased mortality was assessed as of "high", "moderate," or "low," quality, reflecting substantial differences in interpreting the GRADE guidelines. Systematic reviews and guidelines without biostatisticians or epidemiologists as co-authors should be considered potentially problematic.

Hemoglobin oxygen saturation targets in the neonatal intensive care unit: Is there a light at the end of the tunnel? 1

The optimal oxygenation target needed to prevent the extremes of hypoxia and oxygen toxicity in premature and sick newborns has been the subject of much research and debate. The advent of the pulse oximeter has allowed the continuous monitoring of oxyhemoglobin saturation and the delivery of oxygen with greater precision. Well-run, large clinical trials to determine the safest oxygen concentration have led to several revisions in guidelines for neonatal care. However, monitoring of oxyhemoglobin saturation has its limitations and does not provide a comprehensive assessment of tissue oxygenation. To identify optimal oxygen therapy, various other factors (partial pressure of arterial carbon dioxide, hemoglobin concentration, blood pH, and tissue metabolic demand) that influence perfusion and tissue oxygenation need to be considered.