Saturation Target Range Research Articles

Determining an Optimal Oxygen Saturation Target Range Based on Neonatal Maturity: Demonstration of a Decision Tree Analytic

The utility of decision tree machine learning in exploring the interactions among the SpO2 target range, neonatal maturity, and oxemic-risk is demonstrated. METHODS: This observational study used 3 years of paired age-SpO2-PaO2 data from a neonatal ICU. The CHAID decision tree method was used to explore the interaction of postmenstrual age (PMA) on the risk of extreme arterial oxygen levels at six different potential SpO2 target ranges (88–92%, 89–93%, 90–94%, 91–95%, 92–96% and 93–97%). Risk was calculated using a severity-weighted average of arterial oxygen outside the normal range for neonates (50–80 mmHg). RESULTS: In total, 7500 paired data points within the potential target range envelope were analyzed. The two lowest target ranges were associated with the highest risk, and the ranges of 91–95% and 92–96% were associated with the lowest risk. There were shifts in the risk associated with PMA. All the target ranges showed the lowest risk at ≥42 weeks PMA. The lowest risk for preterm infants was within a target range of 92–96% with a PMA of ≤34 weeks. CONCLUSIONS: This study demonstrates the utility of decision tree analytics. These results suggest that SpO2 target ranges that are different from typical range might reduce morbidity and mortality. Further research, including prospective randomized trials, is warranted.

Automated oxygen control for very preterm infants and neurodevelopmental outcome at 2 years−a retrospective cohort study

Faster resolution of hypoxaemic or hyperoxaemic events in preterm infants may reduce long-term neurodevelopmental impairment. Automatic titration of inspiratory oxygen increases time within the oxygen saturation target range and may provide a more prompt response to hypoxic and hyperoxic events. We assessed routinely performed follow-up at 2 years of age after the implementation of automated oxygen control (AOC) as standard care and compared this with a historical cohort. Neurodevelopmental outcomes at 2 years of age were compared for infants born at 24–29 weeks gestational age before (2012–2015) and after (2015–2018) the implementation of AOC as standard of care. The primary outcome was a composite outcome of either mortality or severe neurodevelopmental impairment (NDI), and other outcomes assessed were mild-moderate NDI, Bayley-III composite scores, cerebral palsy GMFCS, and CBCL problem behaviour scores. A total of 289 infants were included in the pre-AOC epoch and 292 in the post-AOC epoch. Baseline characteristics were not significantly different. Fifty-one infants were lost to follow-up (pre-AOC 6.9% (20/289), post-implementation 10.6% (31/292). The composite outcome of mortality or severe NDI was observed in 17.9% pre-AOC (41/229) vs. 24.0% (47/196) post-AOC (p = 0.12). No significant differences were found for the secondary outcomes such as mild-moderate NDI, Bayley-III composite scores, cerebral palsy GMFCS, and problem behaviour scores, with the exception of parent-reported readmissions until the moment of follow-up which was less frequent post-AOC than pre-AOC.Conclusion: In this cohort study, the implementation of automated oxygen control in our NICU as standard of care for preterm infants led to no statistically significant difference in neurodevelopmental outcome at 2 years of age. What is Known:• Neurodevelopmental outcome is linked to hypoxemia, hyperoxaemia and choice of SpO2 target range.• Automated titration of inspired oxygen may provide a faster resolution of hypoxaemic and hyperoxaemic events.What is New: • This cohort study did not find a significant difference in neurodevelopmental outcome at two years of age after implementing automated oxygen control as standard of care.

Survival rate dependent variations in retinopathy of prematurity treatment rates in very low birth weight infants

As increased oxidative stress causes increased mortality and morbidities like bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) in very low birth weight infants (VLBWIs), the conundrum of improved survival but increased ROP observed with the high oxygen saturation target range of 91–95% is difficult to explain. To determine the survival rate-dependent variation in ROP treatment rate, 6292 surviving eligible VLBWIs registered in the Korean Neonatal Network were arbitrarily grouped according to the survival rate of infants at 23–24 weeks’ gestation as group I (> 70%, n = 1626), group II (40–70%, n = 2984) and group III (< 40%, n = 1682). Despite significantly higher survival and lower BPD rates in group I than in groups II and III, the ROP treatment rate was higher in group I than in groups II and III. However, the adjusted odds ratios for ROP treatment were not significantly different between the study groups, and the ROP treatment rate in the infants at 23–24 weeks’ gestation was 21-fold higher than the infants at ≥ 27 weeks’ gestation. The controversial association between improved survival and reduced BPD reflecting quality improvement of neonatal intensive care but increased ROP treatment rate might be primarily attributed to the improved survival of the most immature infants.

Strategies to Prevent Severe Retinopathy of Prematurity: A 2020 Update and Meta-analysis.

The incidence of retinopathy of prematurity (ROP) is showing an increasing trend in the United States. This may be because of increasing survival rates among extremely preterm infants (<25 weeks' gestation) and targeting higher oxygen saturation. Five randomized clinical trials of low versus high oxygen saturation target ranges found increased mortality in the low oxygen saturation target group and an increased incidence of ROP in the high oxygen saturation target group. The American Academy of Pediatrics recommends using an oxygen saturation target range of 90% to 95% in extremely low-birthweight infants. The change of practice to target this higher oxygen saturation range, from admission until discharge, may be contributing to the increasing incidence of ROP in extremely preterm infants. To decrease the incidence of ROP without increasing mortality, 2 new cohort trials suggest gradually increasing oxygen saturation targets as preterm infants mature. There is evidence that human milk, vitamin A, and omega-3 fatty acids can help, in addition to continuous oxygen saturation monitoring, to decrease the risk of ROP. We review this literature and provide a meta-analysis to evaluate the evidence.

Accuracy of pulse oximetry in preterm and term infants is insufficient to determine arterial oxygen saturation and tension.

Oxygen saturation is frequently monitored with pulse oximetry to assess vital signs in critically ill patients. Optimally, pulse oximetry closely tracks arterial oxygen tension (PaO2 ), which provides guidance in oxygen titration. We investigated whether monitoring peripheral oxygen saturation (SpO2 ) could accurately guide oxygen titration in newborn infants. Twenty seven thousand two hundred thirty seven SpO2 readings were retrospectively paired with arterial oxygen saturation (SaO2 ) and PaO2 results from blood gas analyses performed in infants with arterial catheters in place. SpO2 overestimated SaO2 readings by 2.9±5.8%. When pulse oximetry readings were within the defined oxygen saturation target range, 7809 (20.9%) SaO2 values were below and 2830 (7.6%) exceeded the target range. In 57% of patients, PaO2 levels<6kPa was diagnosed while SpO2 readings were>90%. PaO2 >11kPa was recorded in 19% of cases, when SpO2 readings were<95%. Infants treated with supplemental oxygen showed a threefold increased risk of hypoxaemia compared to infants breathing room air. Sensitivity and specificity for detecting upper and lower target range limits were fair to good. For SpO2 values below 91%, ISO quality criteria were no longer fulfilled. Based on arterial blood gas analyses as reference, pulse oximetry readings did not fulfil the performance requirements for titrating oxygen in neonatal patients.

Effects of closed-loop automatic control of the inspiratory fraction of oxygen (FiO2-C) on outcome of extremely preterm infants \u2013 study protocol of a randomized controlled parallel group multicenter trial for safety and efficacy

BackgroundMost extremely low gestational age neonates (ELGANS, postmenstrual age at birth (PMA) < 28 completed weeks) require supplemental oxygen and experience frequent intermittent hypoxemic and hyperoxemic episodes. Hypoxemic episodes and exposure to inadequately high concentrations of oxygen are associated with an increased risk of retinopathy of prematurity (ROP), chronic lung disease of prematurity (BPD), necrotizing enterocolitis (NEC), neurodevelopmental impairment (NDI), and death beyond 36 weeks PMA.Closed-loop automated control of the inspiratory fraction of oxygen (FiO2-C) reduces time outside the hemoglobin oxygen saturation (SpO2) target range, number and duration of hypo- and hyperoxemic episodes and caregivers’ workload. Effects on clinically important outcomes in ELGANs such as ROP, BPD, NEC, NDI and mortality have not yet been studied.MethodsAn outcome-assessor-blinded, randomized controlled, parallel-group trial was designed and powered to study the effect of FiO2-C (in addition to routine manual control (RMC) of FiO2), compared to RMC only, on death and severe complications related to hypoxemia and/or hyperoxemia. 2340 ELGANS with a GA of 23 + 0/7 to 27 + 6/7 weeks will be recruited in approximately 75 European tertiary care neonatal centers. Study participants are randomly assigned to RMC (control-group) or FiO2-C in addition to RMC (intervention-group). Central randomization is stratified for center, gender and PMA at birth (< 26 weeks and ≥ 26 weeks).FiO2-C is provided by commercially available and CE-marked ventilators with an FiO2-C algorithm intended for use in newborn infants. The primary outcome variable (composite of death, severe ROP, BPD or NEC) is assessed at 36 weeks PMA (or, in case of ROP, until complete vascularization of the retina, respectively). The co-primary outcome variable (composite outcome of death, language/cognitive delay, motor impairment, severe visual impairment or hearing impairment) is assessed at 24 months corrected age.DiscussionShort-term studies on FiO2-C showed improved time ELGANs spent within their assigned SpO2 target range, but effects of FiO2-C on clinical outcomes are yet unknown and will be addressed in the FiO2-C trial. This will ensure an appropriate assessment of safety and efficacy before FiO2-C may be implemented as standard therapy.Trial registrationThe study is registered at www.ClinicalTrials.gov: NCT03168516, May 30, 2017.

European Respiratory Society guideline on long-term management of children with bronchopulmonary dysplasia.

This document provides recommendations for monitoring and treatment of children in whom bronchopulmonary dysplasia (BPD) has been established and who have been discharged from the hospital, or who were >36 weeks of postmenstrual age. The guideline was based on predefined Population, Intervention, Comparison and Outcomes (PICO) questions relevant for clinical care, a systematic review of the literature and assessment of the evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. After considering the balance of desirable (benefits) and undesirable (burden, adverse effects) consequences of the intervention, the certainty of the evidence, and values, the task force made conditional recommendations for monitoring and treatment of BPD based on very low to low quality of evidence. We suggest monitoring with lung imaging using ionising radiation in a subgroup only, for example severe BPD or recurrent hospitalisations, and monitoring with lung function in all children. We suggest to give individual advice to parents regarding daycare attendance. With regards to treatment, we suggest the use of bronchodilators in a subgroup only, for example asthma-like symptoms, or reversibility in lung function; no treatment with inhaled or systemic corticosteroids; natural weaning of diuretics by the relative decrease in dose with increasing weight gain if diuretics are started in the neonatal period; and treatment with supplemental oxygen with a saturation target range of 90-95%. A multidisciplinary approach for children with established severe BPD after the neonatal period into adulthood is preferable. These recommendations should be considered until new and urgently needed evidence becomes available.

High vs. Low Initial Oxygen to Improve the Breathing Effort of Preterm Infants at Birth: Study Protocol for a Randomized Controlled Trial.

Background: Although most preterm infants breathe at birth, their respiratory drive is weak and supplemental oxygen is often needed to overcome hypoxia. This could in turn lead to hyperoxia. To reduce the risk of hyperoxia, currently an initial low oxygen concentration (21–30%) is recommended during stabilization at birth, accepting the risk of a hypoxic period. However, hypoxia inhibits respiratory drive in preterm infants. Starting with a higher level of oxygen could lead to a shorter duration of hypoxia by stimulating breathing effort of preterm infants, and combined with subsequent titration based on oxygen saturation, prolonged hyperoxia might be prevented.Study design: This multi-center randomized controlled trial will include 50 infants with a gestational age between 24 and 30 weeks. Eligible infants will be randomized to stabilization with an initial FiO2 of either 1.0 or 0.3 at birth. Hereafter, FiO2 will be titrated based on the oxygen saturation target range. In both groups, all other interventions during stabilization and thereafter will be similar. The primary outcome is respiratory effort in the first 5 min after birth expressed as average minute volume/kg. Secondary outcomes include inspired tidal volumes/kg, rate of rise to maximum tidal volume/kg, percentage of recruitment breaths with tidal volumes above 8 mL/kg, duration of hypoxia and hyperoxia and plasma levels of markers of oxidative stress (8-iso-prostaglandin F2α).Discussion: Current resuscitation guidelines recommend oxygen titration if infants fail to achieve the 25th percentile of the SpO2 reference ranges. It has become clear that, using this approach, most preterm infants are at risk for hypoxia in the first 5 min after birth, which could suppress the breathing effort. In addition, for compromised preterm infants who need respiratory support at birth, higher SpO2 reference ranges in the first minutes after birth might be needed to prevent prolonged hypoxia. Enhancing breathing effort by achieving an adequate level of oxygenation could potentially lead to a lower incidence of intubation and mechanical ventilation in the delivery room, contributing to a lower risk on lung injury in high-risk preterm infants. Measuring 8-iso-prostaglandin F2α could lead to a reflection of the true amount of oxygen exposure in both study groups.

Effect of a smaller target range on the compliance in targeting and distribution of oxygen saturation in preterm infants

BackgroundFollowing recent recommendations, the oxygen saturation (SpO2) target range for preterm infants in our nursery was narrowed towards the higher end from 85%–95% to 90%–95%. We determined the effect of...

Oxygen-saturation targets in extremely preterm infants.

Commentary on: Tarnow-Mordi W, Stenson B, Kirby A, Juszczak E, Donoghoe M, Deshpande S, et al. Outcomes of Two Trials of Oxygen-Saturation Targets in Preterm Infants. N Engl J Med 2016; 374: 749–60. Oxygen-saturation target range in extremely preterm infants is an important question of the daily practice in the NICUs, because significant complications such as ROP and BPD can be associated with oxygen exposure outside physiological boundaries. Observational data suggested that saturation <90% was associated with lower rate of ROP without increased rate of CP or death 1. These data led to practice change: targeting lower oxygen saturations in the NICUs without strong evidence of its safety and efficacy from large RCTs. To answer the question whether a lower saturation target range (85–89%) is superior to a higher saturation target range (91–95%) on an outcome of death or major disability at 18–24 months corrected age, five comparative effectiveness trials of oxygen saturation targeting in infants <28 weeks' gestation (the Neonatal Oxygen Prospective Meta-analysis (NeOProM) Collaboration) were designed. The trials were planned similarly and enrolled ~5000 preterm infants <28 weeks of gestation. The report presented the outcomes of two of these trials, the Australian and U.K. BOOST-II trials in children up to a corrected age of two years. As previously reported 2, the NeOProM trials encountered several problems: (i) an oxygen-saturation calibration problem was found in the pulse oximeters used in two of the NeOProM trials (COT, UK BOOST-II): approximately a third fewer oxygen-saturation values between 87 and 90% were displayed than expected, and values >87% were shifted up by 1–2% points; (ii) additionally, when the SUPPORT trial found that targeting the lower oxygen-saturation range resulted in significantly lower rate of ROP, but higher mortality at discharge compared with the higher oxygen-saturation range 3, the BOOST-II trial was stopped early, because the safety monitoring committees found that the pooled safety analysis of the two trials showed similar results to SUPPORT at 36 weeks' postmenstrual age; (iii) none of the NeOProM trials managed to keep the infants' oxygen saturation in the target range: all median oxygen saturations were higher (>89%) than the predetermined in the lower saturation target group, and there was also significant overlap in oxygen saturations achieved. This meta-analysis of the two BOOST-II trials 4 confirms the findings of the SUPPORT that targeting lower oxygen saturation does not increase major disability, however, increases the rate of death. The authors conclude that at present, the most rigorously evaluated evidence for policy is that targeting an oxygen saturation of 91–95% is safer than targeting an oxygen saturation of 85–89%. However, controversy still remains around dynamic saturation target ranges and alarm settings 2 over the neonatal period. Tissue oxygenation, which depends on multiple factors, including oxygen saturation, is affected by foetal haemoglobin concentration and blood haemoglobin level, along with several other factors. Although the quality of the existing evidence has been graded as moderate to low 5, we think that until more sophisticated methods and individual patient data are available, targeting oxygen saturation between 91 and 95% is a reasonable initial approach for extremely preterm infants. Still, in units with low rates of mortality and but high rates of severe ROP, lower saturation targets have been suggested 2. https://ebneo.org/2017/01/oxygen-saturation-targets-in-extremely-preterm-infants None. None.

Clinical evaluation of a novel adaptive algorithm for automated control of oxygen therapy in preterm infants on non-invasive respiratory support

ObjectiveTo evaluate the performance of a novel rapidly responsive proportional-integral-derivative (PID) algorithm for automated oxygen control in preterm infants with respiratory insufficiency.DesignInterventional study of a 4-hour period of automated oxygen...

Lower early postnatal oxygen saturation target and risk of ductus arteriosus closure failure.

Early postnatal hyperoxia is a major risk factor for retinopathy of prematurity (ROP) in extremely premature infants. To reduce the occurrence of ROP, we adopted a lower early postnatal oxygen saturation (SpO2 ) target range (85-92%) from April 2011. Lower SpO2 target range, however, may lead to hypoxemia and an increase in the risk of ductus arteriosus (DA) closure failure. The aim of this study was therefore to determine whether a lower SpO2 target range, during the early postnatal stage, increases the risk of DA closure failure. Infants born at <28 weeks' gestation were enrolled in this study. Oxygen saturation target range during the first postnatal 72 h was 84-100% in study period 1 and 85-92% in period 2. Eighty-two infants were included in period 1, and 61 were included in period 2. The lower oxygen saturation target range increased the occurrence of hypoxemia during the first postnatal 72 h. Prevalence of DA closure failure in period 2 (21%) was significantly higher than that in period 1 (1%). On multivariate logistic regression analysis, the lower oxygen saturation target range was an independent risk factor for DA closure failure. Lower early postnatal oxygen saturation target range increases the risk of DA closure failure.

Usual Care and Informed Consent in Clinical Trials of Oxygen Management in Extremely Premature Infants.

ObjectiveThe adequacy of informed consent in the Surfactant, Positive Pressure, and Pulse Oximetry Randomized Trial (SUPPORT) has been questioned. SUPPORT investigators and publishing editors, heads of government study funding agencies, and many ethicists have argued that informed consent was adequate because the two oxygen saturation target ranges studied fell within a range commonly recommended in guidelines. We sought to determine whether each oxygen target as studied in SUPPORT and four similar randomized controlled trials (RCTs) was consistent with usual care.Design/Participants/SettingPubMed, EMBASE, Web of Science, and Scopus were searched for English articles back to 1990 providing information on usual care oxygen management in extremely premature infants. Data were extracted on intended and achieved oxygen saturation levels as determined by pulse oximetry. Twenty-two SUPPORT consent forms were examined for statements about oxygen interventions.ResultsWhile the high oxygen saturation target range (91 to 95%) was consistent with usual care, the low range (85 to 89%) was not used outside of the SUPPORT trial according to surveys and clinical studies of usual care. During usual care, similar lower limits (< 88%) were universally paired with higher upper limits (≥ 92%) and providers skewed achieved oxygen saturations toward the upper-end of these intended ranges. Blinded targeting of a low narrow range resulted in significantly lower achieved oxygen saturations and a doubling of time spent below the lower limit of the intended range compared to usual care practices. The SUPPORT consent forms suggested that the low oxygen saturation arm was a widely practiced subset of usual care.ConclusionsSUPPORT does not exemplify comparative effectiveness research studying practices or therapies in common use. Descriptions of major differences between the interventions studied and commonly practiced usual care, as well as potential risks associated with these differences, are essential elements of adequate informed consent.

Oxygen saturation target range for extremely preterm infants: a systematic review and meta-analysis.

The optimal oxygen saturation (SpO2) target for extremely preterm infants is unknown. To systematically review evidence evaluating the effect of restricted vs liberal oxygen exposure on morbidity and mortality in extremely preterm infants. MEDLINE, PubMed, CENTRAL, and CINAHL databases from their inception to March 31, 2014, and abstracts submitted to Pediatric Academic Societies from 2000 to 2014. All published randomized trials evaluating the effect of restricted (SpO2, 85%-89%) vs liberal (SpO2, 91%-95%) oxygen exposure in preterm infants (<28 weeks' gestation at birth). All meta-analyses were performed using Review Manager 5.2. The Cochrane risk-of-bias tool was used to assess study quality. The summary of the findings and the level of confidence in the estimate of effect were assessed using GRADEpro. Treatment effect was analyzed using a random-effects model. Death before hospital discharge, death or severe disability before 24 months, death before 24 months, neurodevelopmental outcomes, hearing loss, bronchopulmonary dysplasia, necrotizing enterocolitis, and severe retinopathy of prematurity. Five trials were included in the final synthesis. These studies had a similar design with a prespecified composite outcome of death/disability at 18 to 24 months corrected for prematurity; however, this outcome has not been reported for 2 of the 5 trials. There was no difference in the outcome of death/disability before 24 months (risk ratio [RR], 1.02 [95% CI, 0.92-1.14]). Mortality before 24 months was not different (RR, 1.13 [95% CI, 0.97-1.33]); however, a significant increase in mortality before hospital discharge was found in the restricted oxygen group (RR, 1.18 [95% CI, 1.03-1.36]). The rates of bronchopulmonary dysplasia, neurodevelopmental outcomes, hearing loss, and retinopathy of prematurity were similar between the 2 groups. Necrotizing enterocolitis occurred more frequently in infants on restricted oxygen (RR, 1.24 [95% CI, 1.05-1.47]). Using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria, we found that the quality of evidence for these outcomes was moderate to low. Although infants cared for with a liberal oxygen target had significantly lower mortality before hospital discharge than infants cared for with a restricted oxygen target, the quality of evidence for this estimate of effect is low. Necrotizing enterocolitis occurred less frequently in the liberal oxygen group. We found no significant differences in death or disability at 24 months, bronchopulmonary dysplasia, retinopathy of prematurity, neurodevelopmental outcomes, or hearing loss at 24 months.

Cerebral desaturations in preterm infants: a crossover trial on influence of oxygen saturation target range

ObjectiveTo test the hypothesis that a higher pulsoximetric arterial oxygen saturation (SpO2) target range is associated with reduced cerebral tissue oxygen desaturations from baseline during events of hypoxaemia or bradycardia.DesignRandomised...

Low Oxygen Saturation Target Range is Associated with Increased Incidence of Intermittent Hypoxemia

To test the hypothesis that preterm infants randomized to a low vs high O(2) saturation target range have a higher incidence of intermittent hypoxemia. A subcohort of 115 preterm infants with high resolution pulse oximetry enrolled in the Surfactant, Positive Pressure, and Oxygenation Randomized Trial were randomized to low (85%-89%) or high (91%-95%) O(2) saturation target ranges. Oxygen saturation was monitored until 36 weeks postmenstrual age or until the infant was breathing room air without respiratory support for ≥72 hours. The low target O(2) saturation group had a higher rate of intermittent hypoxemia (≤80% for ≥10 seconds and ≤3 minutes) prior to 12 days and beyond 57 days of life (P < .05). The duration shortened (P < .0001) and the severity increased (P < .0001) with increasing postnatal age with no differences between target saturation groups. The higher rate of intermittent hypoxemia events in the low target group was associated with a time interval between events of <1 minute. A low O(2) saturation target was associated with an increased rate of intermittent hypoxemia events that was dependent on postnatal age. The duration and severity of events was comparable between target groups. Further investigation is needed to assess the role of intermittent hypoxemia and their timing on neonatal morbidity.

Safe use of emergency oxygen in chronic respiratory disease

There is good evidence that long-term oxygen therapy (LTOT) increases life expectancy in patients with severe hypoxaemic chronic obstructive pulmonary disease (COPD). For this reason, LTOT is the largest category of home oxygen use in adults, often supplemented by ambulatory oxygen to allow patients to mobilize. Many patients with COPD who are not sufficiently hypoxaemic to require LTOT have been advised to use short-burst oxygen therapy in the hope and expectation that it would relieve breathlessness after exertion. Although this is not a medical emergency, it is the commonest nonelective use of oxygen for patients with COPD, and the National Health Service in the United Kingdom spends about 18 million pounds per year on this treatment. Despite the widespread use of shortburst oxygen therapy in the United Kingdom, two systematic reviews have concluded that this form of oxygen use has no proven benefit in non-hypoxaemic patients with COPD, and the most recent (and largest) clinical trial has shown no benefit from short-burst oxygen therapy after exertion for patients with severe COPD, even among patients who desaturate on exertion. The advice in the National Institute for Clinical Excellence COPD guideline is that short-burst oxygen therapy should only be considered for episodes of severe breathlessness in patients with COPD not relieved by other treatments and only if an improvement in breathlessness following therapy has been documented. Patients with COPD of sufficient severity to require LTOT are at risk of acute exacerbations of COPD with worsening hypoxaemia. These patients are especially likely to be vulnerable to type 2 respiratory failure (hypercapnia) if high concentrations of oxygen are given. Hypercapnic respiratory failure can lead to increased risk of requirement for mechanical ventilation and increased risk of death when excessive oxygen is administered. Therefore, it is advisable for patients in this situation to call for medical assistance rather than simply turning up the flow rate of oxygen in the home environment. The British Thoracic Society guideline for emergency oxygen therapy recommends an oxygen saturation target range of 88–92% for most such patients although some patients may require a lower target range based on previous blood gas analysis. Most patients in this situation will require urgent transport to hospital where blood gases can be sampled and controlled oxygen therapy can be given. Patients with prior episodes of hypercapnic respiratory failure may be provided with an oxygen alert card and a personal 24% or 28% Venturi mask to ensure that they are not exposed to the risks of hyperoxic hypercapnia during ambulance transfers to hospital. Patients with severe hypoxaemia associated with hypercapnia and acidosis are likely to require treatment with noninvasive ventilation.

Effects of low oxygen saturation limits on the ductus arteriosus in extremely low birth weight infants

Postnatal increase in oxygen promotes constriction of the patent ductus arteriosus (PDA). According to the findings of prospective observational studies, the clinical practice of targeting lower fractional oxygen saturation between 70 and 90% has been associated with a reduced incidence of severe retinopathy of prematurity (ROP) without affecting survival or neurodevelopmental disability at 1 year of age. Our objective was to investigate the impact of the use of a lower oxygen saturation target range on the incidence of early hemodynamically significant PDA (hsPDA) and the need for ductal ligation in extremely low birth weight (ELBW, <1000 g) infants. In this retrospective study, we analyzed data from 263 ELBW infants managed 4 years before (episode I: target oxygen saturation 89 to 94%) and after (episode II: target oxygen saturation 83 to 89%) implementation of the use of lower oxygen saturation limits in two neonatal intensive care units. Infants with a birth weight of 1000 to 1500 g were managed with the same oxygen saturation target range (89 to 94%) during both episodes, and they served as controls. Parametric and nonparametric tests were used as appropriate and multivariate logistic regression models were used to correct for confounders. There was an increase in the incidence of hsPDA (63.2 vs 74.8%, P=0.043), without an increase in the need for surgical ligation (24.2 vs 29.9%, P=0.3) after implementation of the lower oxygen saturation target range policy. After adjusting for confounders, there was an increase in the odds of having an hsPDA (odds ratio (OR) 1.77, 95% confidence interval (CI) (1.03 to 3.06), P=0.04) but the odds for ductal ligation did not change in episode II (OR 1.25, 95% CI (0.70 to 2.25), P=0.4). The incidence of ROP > or = stage III (50.7 vs 15.7%; P<0.0001) and the need for laser ablation (33.8% vs 8.7%; P<0.0001) were significantly reduced. There was no change in the incidence of hsPDA or ductal ligation in the control group. Targeting lower oxygen saturation limits to minimize periods of hyperoxemia in ELBW infants reduced the incidence of severe ROP and the need for laser ablation. The incidence of early hsPDA was increased; however, final closure rate and the incidence of surgical ligation of the ductus arteriosus were not affected.

Nurse Opinions and Pulse Oximeter Saturation Target Limits for Preterm Infants

The objectives of this study were to compare pulse oximeter saturation limits targeted by nurses for extremely preterm infants during routine care with nurse opinions regarding appropriate pulse oximeter saturation limits and with policy-specified pulse oximeter saturation limits and to identify factors that influence pulse oximeter saturation limits targeted by nurses. We surveyed nurses in US NICUs with neonatal-perinatal fellowships in 2004. Data collected included pulse oximeter saturation limits targeted by nurses and by NICU policy when present, nurses' opinions about appropriate pulse oximeter saturation limits, and NICU and nurse characteristics. Factors associated with pulse oximeter saturation limits targeted by nurses were identified with hierarchical linear modeling. Among those eligible, 2805 (45%) nurses in 59 (60%) NICUs responded. Forty (68%) of 59 NICUs had a policy that specified a pulse oximeter saturation target range for extremely preterm infants. Among 1957 nurses at NICUs with policies, 540 (28%) accurately identified the upper and lower limits of their NICU's policy and also targeted these values in practice. NICU-specific SDs for individual nurse target limits were less at NICUs with versus without a policy for both upper and lower limits. Hierarchical linear modeling identified presence of pulse oximeter saturation policy, NICU-specific nurse group opinion, and individual nurse opinion as factors significantly associated with individual pulse oximeter saturation target limits. For each percentage point increase in individual opinion upper limit, the individual target upper limit increased by 0.41 percentage point at NICUs with a policy compared with 0.6 percentage point at NICUs with no policy. Presence of policy-specified pulse oximeter saturation limits, nurse group opinion, and individual nurse opinion were independently associated with individual nurse pulse oximeter saturation target limits during routine care of extremely preterm infants. The presence of a policy reduced the influence of individual nurse opinion on targeted pulse oximeter saturation limits and reduced variation among nurse target limits within NICUs.

Achieved Versus Intended Pulse Oximeter Saturation in Infants Born Less Than 28 Weeks' Gestation: The AVIOx Study

The objective of this study was to document pulse oximeter saturation levels achieved in the first 4 weeks of life in infants who were born at < 28 weeks' gestation, compared with the levels that were targeted by local policy, and examine factors that are associated with compliance with the target range. Infants who were < 28 weeks' gestation and < or = 96 hours of age were enrolled in a prospective, multicenter cohort study. Oximetry data were collected with masked signal-extraction oximeters for a 72-hour period in each of the first 4 weeks of life. Data were compared with the pulse oximeter saturation target range prescribed by local institutional policy. Factors that were associated with intended range compliance were identified with hierarchical modeling. Fourteen centers from 3 countries enrolled 84 infants with mean +/- SD birth weight of 863 +/- 208 g and gestational age of 26 +/- 1.4 weeks. Oxygen saturation policy limits ranged between 83% and 92% for lower limits and 92% and 98% for upper limits. For infants who received respiratory support, median pulse oximeter saturation level achieved was 95%. Center-specific medial levels were within the intended range at 12 centers. Centers maintained infants within their intended range 16% to 64% of the time but were above range 20% to 73% of the time. In hierarchical modeling, wider target ranges, higher target range upper limits, presence of a policy of setting oximeter alarms close to the target range limits, and lower gestational age were associated with improved target range compliance. Success with maintaining the intended pulse oximeter saturation range varied substantially among centers, among patients within centers, and for individual patients over time. Most noncompliance was above the intended range. Methods for improving compliance and the effect of improved compliance on neonatal outcomes require additional research.