Automated FiO2 control: nice to have, or an essential addition to neonatal intensive care?

New Modes of Respiratory Support for the Premature Infant: Automated Control of Inspired Oxygen Concentration

Most extremely premature infants have respiratory instability that can manifest as frequent episodes of intermittent hypoxemia. Although caregivers target clinically recommended ranges of arterial oxygen saturation (oxygen saturation as measured by pulse oximetry [Spo₂]), consistent maintenance of these ranges is not always achieved. Excessive administration of supplemental oxygen combined with limited staff resources increases exposure to extreme Spo₂ levels. In this population, exposure to hyperoxemia and prolonged episodes of intermittent hypoxemia have been associated with damage to the eye and lung and impaired neurodevelopment. To improve Spo₂ targeting, various systems for automated control of inspired oxygen have been developed recently.

Cerebral and splanchnic oxygenation during automated control of inspired oxygen (FiO2 ) in preterm infants

OBJECTIVES

Our aim in this study was to assess the effect of the Predictive Intelligent Control of Oxygenation (PRICO^® ) system on cerebral (rSO₂ C) and splanchnic (rSO₂ S) oxygenation in a cohort of preterm infants with frequent desaturations.

METHODS

Twenty infants with gestational age <32 weeks (n = 20) were assigned in random sequence to 12 h of automated or manual adjustment of FiO₂ . Over this period, they were studied continuously by near-infrared spectroscopy (NIRS).

RESULTS

We found that rSO₂ C [68.0% (60.5%-74.7%) vs. 68.5% (62%-72%); p = .824] and rSO₂ S [27.0% (17.3%-45.7%) vs. 27.0% (15%-53%); p = .878] were similar during automatic and manual control of FiO₂ . Time spent with SpO₂ 90%-95% was higher during the automatic than manual control of FiO₂ , while time spent with SpO₂ <80% or >95% was lower.

CONCLUSIONS

Automated control of FiO₂ with PRICO^® system did not improve brain and splanchnic oxygenation in comparison with manual control in a cohort of preterm infants, but it significantly decreased SpO₂ fluctuations and limited the duration of both hypoxemia and hyperoxemia.

In vitro evaluation of delays in the adjustment of the fraction of inspired oxygen during CPAP: effect of flow and volume

BACKGROUND

Adjusting the fraction of inspired oxygen (FiO₂) delivered to preterm infants to keep their oxygen saturation within target range remains challenging. Closed-loop automated FiO₂ control increases the time infants spend within the assigned target range. The delay with which FiO₂ adjustments at the ventilator result in a change in the inspired gas limits the performance of both manual and automated controls.

OBJECTIVE

To evaluate the equilibration time (T_eq) between FiO₂ adjustments and changes in FiO₂ reaching the patient.

METHODS

In vitro determination of the delay in FiO₂ adjustments at the ventilator at 5 and 8 L/min of gas flow and two different humidifier/ventilator circuit volumes (840 and 432 mL).

RESULTS

T_eq values were 31, 23, 20 and 17 s for the volume-flow combinations 840 mL+5 L/min, 840 mL+8 L/min, 432 mL+5 L/min and 432 mL+8 L/min, respectively.

CONCLUSION

The identified delay seems clinically relevant and should be taken into account during manual and automatic control of FiO₂.

Is faster better? A randomised crossover study comparing algorithms for closed-loop automatic oxygen control

OBJECTIVE

Closed-loop automatic control (CLAC) of the fractional inspired oxygen (FiO₂) improved oxygen administration to preterm infants on respiratory support. We investigated whether a revised CLAC algorithm (CLAC_fast, ≤2 FiO₂ adjustments/min), compared with routine manual control (RMC_only), increased the proportion of time with arterial haemoglobin oxygen saturation measured by pulse oximetry within prespecified target ranges (Target%) while not being inferior to the original algorithm (CLAC_slow: ≤0.3 FiO₂ adjustments/min).

DESIGN

Unblinded randomised controlled crossover study comparing three modes of FiO₂ control in random order for 8 hours each: RMC supported by CLAC_fast was compared with RMC_only and RMC supported by CLAC_slow. A computer-generated list of random numbers using a block size of six was used for the allocation sequence.

SETTING

Two German tertiary university neonatal intensive care units.

PATIENTS

Of 23 randomised patients, 19 were analysed (mean±SD gestational age 27±2 weeks; age at randomisation 24±10 days) on non-invasive (n=18) or invasive (n=1) respiratory support at FiO₂ >0.21.

MAIN OUTCOME MEASURE

Target%.

RESULTS

Mean±SD [95% CI] Target% was 68%±11% [65% to 71%] for CLAC_fast versus 65%±11% [61% to 68%] for CLAC_slow versus 58%±11% [55% to 62%] for RMC_only. Prespecified hypothesis tests of: (A) superiority of CLAC_fast versus RMC_only and (B) non-inferiority of CLAC_fast versus CLAC_slow with margin of 5% yielded one-sided p values of <0.001 for both comparisons.

CONCLUSIONS

This revised and faster CLAC algorithm was still superior to routine care in infants on respiratory support and not inferior to a previously tested slower algorithm.

TRIAL REGISTRATION NUMBER

NCT03163108.

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

Background

Most 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.

Methods

An 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.

Discussion

Short-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 registration

The study is registered at www.ClinicalTrials.gov: NCT03168516, May 30, 2017.

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.

Targeting Arterial Oxygen Saturation by Closed-Loop Control of Inspired Oxygen in Preterm Infants

Exposure to hyperoxemia from excessive oxygen supplementation and episodes of intermittent hypoxemia have been associated with damage to the eye, lung, and central nervous system in premature infants. The inherent respiratory instability of the premature infant combined with limited staffing or equipment resources often affect SpO₂ targeting and increase exposure to extreme SpO₂ levels. Multiple systems for closed loop control of inspired oxygen have been developed to improve SpO₂ targeting. This article reviews the evidence provided by clinical studies evaluating the efficacy of these systems in extreme premature infants.

Achieved Oxygenation Saturations and Outcome in Extremely Preterm Infants

Infants in the Neonatal Oxygenation Prospective Meta-analysis trials were randomized to SpO₂ targets of 85% to 89% or 91% to 95%. Group allocation was masked. Different outcomes are likely partially attributable to differences in achieved SpO₂. Infants randomized to the lower range had higher than intended readings. SpO₂ distributions of infants in the low-range group of the Benefits of Oxygen Saturation Targeting II UK trial who died or developed necrotizing enterocolitis were centered around 90% to 92%. These achieved SpO₂ distributions caution against using lower SpO₂ target ranges early or throughout the clinical course in extremely preterm infants.

Automated control of inspired oxygen (FiO2 ) in preterm infants: Literature review

The vast majority (95%) of very preterm infants receive oxygen-therapy monitored by oxygen pulse saturation (SpO₂ ). However, they spend a significant percentage of time out of the SpO₂ target with a high risk of severe complications such as bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP). Recently, systems allowing the automated control of inspired oxygen (FiO₂ ) for patient delivery to maintain target SpO₂ has been become commercially available. We reviewed literature and individuated sixteen studies on the effectiveness of automated control of FiO₂ in preterm infants. These studies demonstrate that automated devices are significantly more effective than manual control in maintaining target SpO₂ and in preventing hyperoxia, while they seem to be less effective in preventing hypoxia. The studies were very heterogeneous for design, population size, duration, and device used, and this precludes firm conclusions regarding effectiveness and best setting of these systems. Moreover, none of the studies investigated if automated control of FiO₂ can actually improve outcome in preterm infants. We conclude that further large-scale studies are warranted to assess the actual clinical relevance of these devices and to decide if they should become the standard of care.

Automated versus manual control of inspired oxygen to target oxygen saturation in preterm infants: a systematic review and meta-analysis

OBJECTIVES

To conduct a systematic review of clinical trials comparing automated versus manual fraction of inspired oxygen (FiO₂) control to target oxygen saturation (SpO₂) in preterm infants.

DESIGN

The authors searched MEDLINE, Embase, CENTRAL, and CINAHL from inception upto December 2016, reviewed conference proceedings and sought results of unpublished trials. Studies were included if automated FiO₂ control was compared to manual control in preterm infants on positive pressure respiratory support. The primary outcome was percentage of time spent within the target SpO₂ range. Summary mean differences (MD) were computed using random effects model.

RESULTS

Out of 276 identified studies 10 met the inclusion criteria. Automated FiO₂ control significantly improved time being spent within the target SpO₂ range [MD: 12.8%; 95% CI: 6.5-19.2%; I² = 90%]. Periods of hyperoxia (MD:-8.8%; 95% CI: -15 to -2.7%), severe hypoxia(SpO₂ < 80%)(MD: -0.9%;95%CI: -1.5 to -0.4%) and hypoxic events (MD: -5.6%; 95% CI: -9.1 to -2.1%) were significantly reduced with automated control.

CONCLUSION

Automated FiO₂ adjustment provides significant improvement of time in target saturations, reduces periods of hyperoxia, and severe hypoxia in preterm infants on positive pressure respiratory support.

Pathophysiology, screening and treatment of ROP: A multi-disciplinary perspective

The population of infants at risk for retinopathy of prematurity (ROP) varies by world region; in countries with well developed neonatal intensive care services, the highest risk infants are those born at less than 28 weeks gestational age (GA) and less than 1 kg at birth, while, in regions where many aspects of neonatal intensive and ophthalmological care are not routinely available, more mature infants up to 2000 g at birth and 37 weeks GA are also at risk for severe ROP. Treatment options for both groups of patients include standard retinal laser photocoagulation or, more recently, intravitreal anti-VEGF drugs. In addition to detection and treatment of ROP, this review highlights new opportunities created by telemedicine, where screening and diagnosis of ROP in remote locations can be undertaken by non-ophthalmologists using digital fundus cameras. The ophthalmological care of the ROP infant is undertaken in the wider context of neonatal care and general wellbeing of the infant. Because of this context, this review takes a multi-disciplinary perspective with contributions from retinal vascular biologists, pediatric ophthalmologists, an epidemiologist and a neonatologist. This review highlights the latest insights regarding cellular and molecular mechanisms in the formation of the retinal vasculature in the human infant, pathogenesis of ROP, detection and treatment of severe ROP, the risks and benefits of anti-VEGF therapy, the identification of new therapies over the horizon, and the optimal neonatal care regimen for best ROP outcomes, and the benefits and pitfalls of telemedicine in the remote screening and diagnosis of ROP, all of which have the potential to improve ROP outcomes.