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

Closed-loop oxygen usage during invasive mechanical ventilation of pediatric patients (CLOUDIMPP): a randomized controlled cross-over study

Background

The aim of this study is the evaluation of a closed-loop oxygen control system in pediatric patients undergoing invasive mechanical ventilation (IMV).

Methods

Cross-over, multicenter, randomized, single-blind clinical trial. Patients between the ages of 1 month and 18 years who were undergoing IMV therapy for acute hypoxemic respiratory failure (AHRF) were assigned at random to either begin with a 2-hour period of closed-loop oxygen control or manual oxygen titrations. By using closed-loop oxygen control, the patients' SpO2 levels were maintained within a predetermined target range by the automated adjustment of the FiO2. During the manual oxygen titration phase of the trial, healthcare professionals at the bedside made manual changes to the FiO2, while maintaining the same target range for SpO2. Following either period, the patient transitioned to the alternative therapy. The outcomes were the percentage of time spent in predefined SpO2 ranges ±2% (primary), FiO2, total oxygen use, and the number of manual adjustments.

Findings

The median age of included 33 patients was 17 (13-55.5) months. In contrast to manual oxygen titrations, patients spent a greater proportion of time within a predefined optimal SpO2 range when the closed-loop oxygen controller was enabled (95.7% [IQR 92.1-100%] vs. 65.6% [IQR 41.6-82.5%]), mean difference 33.4% [95%-CI 24.5-42%]; P < 0.001). Median FiO2 was lower (32.1% [IQR 23.9-54.1%] vs. 40.6% [IQR 31.1-62.8%]; P < 0.001) similar to total oxygen use (19.8 L/h [IQR 4.6-64.8] vs. 39.4 L/h [IQR 16.8-79]; P < 0.001); however, median SpO2/FiO2 was higher (329.4 [IQR 180-411.1] vs. 246.7 [IQR 151.1-320.5]; P < 0.001) with closed-loop oxygen control. With closed-loop oxygen control, the median number of manual adjustments reduced (0.0 [IQR 0.0-0.0] vs. 1 [IQR 0.0-2.2]; P < 0.001).

Conclusion

Closed-loop oxygen control enhances oxygen therapy in pediatric patients undergoing IMV for AHRF, potentially leading to more efficient utilization of oxygen. This technology also decreases the necessity for manual adjustments, which could reduce the workloads of healthcare providers.

Clinical Trial Registration

This research has been submitted to ClinicalTrials.gov (NCT05714527).

Comparison of two different oxygen saturation target ranges for automated oxygen control in preterm infants: a randomised cross-over trial

OBJECTIVE

To compare the effect of peripheral oxygen saturation (SpO2) target range (TR) (either 91%-95% and 92%-96%) on the frequency and duration of hypoxic and hyperoxic episodes while on automated oxygen control using the OxyGenie controller.

DESIGN

Randomised cross-over study.

SETTING

Tertiary-level neonatal unit in the Netherlands.

PATIENTS

Infants (n=27) with a median (IQR) gestational age of 27+0 (25+5-27+3) weeks and postnatal age of 16 (10-22) days, receiving invasive or non-invasive respiratory support.

INTERVENTIONS

In both groups supplemental oxygen was titrated to a TR of 91%-95% (TRlow) or 92%-96% (TRhigh) by the OxyGenie controller (SLE6000 ventilator) for 24 hours each, in random sequence. After a switch in TR, a 1-hour washout period was applied to prevent carry-over bias.

MAIN OUTCOME MEASURES

Frequency and duration of hypoxic (SpO2<80% for ≥1 s) and hyperoxic episodes (SpO2>98% for ≥1 s).

RESULTS

Hypoxic episodes were less frequent when the higher range was targeted (TRhigh vs TRlow: 2.5 (0.7-6.2)/hour vs 2.4 (0.9-10.2)/hour, p=0.02), but hyperoxic episodes were more frequent (5.3 (1.8-12.3)/hour vs 2.9 (1.0-7.1)/hour, p<0.001). The duration of the out-of-range episodes was not significantly different (hypoxia: 4.7 (2.8-7.1) s vs 4.4 (3.7-6.5) s, p=0.67; hyperoxia: 4.3 (3.3-4.9) s vs 3.9 (2.8-5.5) s, p=0.89).

CONCLUSION

Targeting a higher SpO2 TR with the OxyGenie controller reduced hypoxic episodes but increased hyperoxic episodes. This study highlights the feasibility of using an automated oxygen titration device to explore the effects of subtle TR adjustments on clinical outcomes in neonatal care.

TRIAL REGISTRATION NUMBER

NL9662.

Pulse oximetry signal loss during hypoxic episodes in preterm infants receiving automated oxygen control

The aim of this study was to analyze signal loss (SL) resulting from low signal quality of pulse oximetry-derived hemoglobin oxygen saturation (SpO2) measurements during prolonged hypoxemic episodes (pHE) in very preterm infants receiving automatic oxygen control (AOC). We did a post hoc analysis of a randomized crossover study of AOC, programmed to set FiO2 to "back-up FiO2" during SL. In 24 preterm infants (median (interquartile range)) gestational age 25.3 (24.6 to 25.6) weeks, recording time 12.7 h (12.2 to 13.6 h) per infant, we identified 76 pHEs (median duration 119 s (86 to 180 s)). In 50 (66%) pHEs, SL occurred for a median duration of 51 s (33 to 85 s) and at a median frequency of 2 (1 to 2) SL-periods per pHE. SpO2 before and after SL was similar (82% (76 to 88%) vs 82% (76 to 87%), p = 0.3)).  Conclusion: SL is common during pHE and must hence be considered in AOC-algorithm designs. Administering a "backup FiO2" (which reflects FiO2-requirements during normoxemia) during SL may prolong pHE with SL.  Trial registration: The study was registered at www.

CLINICALTRIALS

gov under the registration no. NCT03785899.

WHAT IS KNOWN

• Previous studies examined SpO2 signal loss (SL) during routine manual oxygen control being rare, but pronounced in lower SpO2 states. • Oxygen titration during SL is unlikely to be beneficial as SpO2 may recover to a normoxic range.

WHAT IS NEW

• Periods of low signal quality of SpO2 are common during pHEs and while supported with automated oxygen control (SPOC), FiO2 is set to a back-up value reflecting FiO2 requirements during normoxemia in response to SL, although SpO2 remained below target until signal recovery. • FiO2 overshoots following pHEs were rare during AOC and occurred with a delayed onset; therefore, increased FiO2 during SL does not necessarily lead to overshoots.

Automated oxygen delivery for preterm infants with respiratory dysfunction

BACKGROUND

Many preterm infants require respiratory support to maintain an optimal level of oxygenation, as oxygen levels both below and above the optimal range are associated with adverse outcomes. Optimal titration of oxygen therapy for these infants presents a major challenge, especially in neonatal intensive care units (NICUs) with suboptimal staffing. Devices that offer automated oxygen delivery during respiratory support of neonates have been developed since the 1970s, and individual trials have evaluated their effectiveness.

OBJECTIVES

To assess the benefits and harms of automated oxygen delivery systems, embedded within a ventilator or oxygen delivery device, for preterm infants with respiratory dysfunction who require respiratory support or supplemental oxygen therapy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, CINAHL, and clinical trials databases without language or publication date restrictions on 23 January 2023. We also checked the reference lists of retrieved articles for other potentially eligible trials.

SELECTION CRITERIA

We included randomised controlled trials and randomised cross-over trials that compared automated oxygen delivery versus manual oxygen delivery, or that compared different automated oxygen delivery systems head-to-head, in preterm infants (born before 37 weeks' gestation).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our main outcomes were time (%) in desired oxygen saturation (SpO2) range, all-cause in-hospital mortality by 36 weeks' postmenstrual age, severe retinopathy of prematurity (ROP), and neurodevelopmental outcomes at approximately two years' corrected age. We expressed our results using mean difference (MD), standardised mean difference (SMD), and risk ratio (RR) with 95% confidence intervals (CIs). We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 18 studies (27 reports, 457 infants), of which 13 (339 infants) contributed data to meta-analyses. We identified 13 ongoing studies. We evaluated three comparisons: automated oxygen delivery versus routine manual oxygen delivery (16 studies), automated oxygen delivery versus enhanced manual oxygen delivery with increased staffing (three studies), and one automated system versus another (two studies). Most studies were at low risk of bias for blinding of personnel and outcome assessment, incomplete outcome data, and selective outcome reporting; and half of studies were at low risk of bias for random sequence generation and allocation concealment. However, most were at high risk of bias in an important domain specific to cross-over trials, as only two of 16 cross-over trials provided separate outcome data for each period of the intervention (before and after cross-over). Automated oxygen delivery versus routine manual oxygen delivery Automated delivery compared with routine manual oxygen delivery probably increases time (%) in the desired SpO2 range (MD 13.54%, 95% CI 11.69 to 15.39; I2 = 80%; 11 studies, 284 infants; moderate-certainty evidence). No studies assessed in-hospital mortality. Automated oxygen delivery compared to routine manual oxygen delivery may have little or no effect on risk of severe ROP (RR 0.24, 95% CI 0.03 to 1.94; 1 study, 39 infants; low-certainty evidence). No studies assessed neurodevelopmental outcomes. Automated oxygen delivery versus enhanced manual oxygen delivery There may be no clear difference in time (%) in the desired SpO2 range between infants who receive automated oxygen delivery and infants who receive manual oxygen delivery (MD 7.28%, 95% CI -1.63 to 16.19; I2 = 0%; 2 studies, 19 infants; low-certainty evidence). No studies assessed in-hospital mortality, severe ROP, or neurodevelopmental outcomes. Revised closed-loop automatic control algorithm (CLACfast) versus original closed-loop automatic control algorithm (CLACslow) CLACfast allowed up to 120 automated adjustments per hour, whereas CLACslow allowed up to 20 automated adjustments per hour. CLACfast may result in little or no difference in time (%) in the desired SpO2 range compared to CLACslow (MD 3.00%, 95% CI -3.99 to 9.99; 1 study, 19 infants; low-certainty evidence). No studies assessed in-hospital mortality, severe ROP, or neurodevelopmental outcomes. OxyGenie compared to CLiO2 Data from a single small study were presented as medians and interquartile ranges and were not suitable for meta-analysis.

AUTHORS' CONCLUSIONS

Automated oxygen delivery compared to routine manual oxygen delivery probably increases time in desired SpO2 ranges in preterm infants on respiratory support. However, it is unclear whether this translates into important clinical benefits. The evidence on clinical outcomes such as severe retinopathy of prematurity are of low certainty, with little or no differences between groups. There is insufficient evidence to reach any firm conclusions on the effectiveness of automated oxygen delivery compared to enhanced manual oxygen delivery or CLACfast compared to CLACslow. Future studies should include important short- and long-term clinical outcomes such as mortality, severe ROP, bronchopulmonary dysplasia/chronic lung disease, intraventricular haemorrhage, periventricular leukomalacia, patent ductus arteriosus, necrotising enterocolitis, and long-term neurodevelopmental outcomes. The ideal study design for this evaluation is a parallel-group randomised controlled trial. Studies should clearly describe staffing levels, especially in the manual arm, to enable an assessment of reproducibility according to resources in various settings. The data of the 13 ongoing studies, when made available, may change our conclusions, including the implications for practice and research.

Measuring Oxygenation in Newborn Infants with Targeted Oxygen Ranges (MONITOR): a randomised crossover pilot study

OBJECTIVE

The Neonatal Oxygenation Prospective Meta-analysis (NeOProM) Collaboration showed that high (91-95%) versus low (85-89%) SpO2 targets reduced mortality. Trials of higher targets are needed to determine whether any more survival advantage may be gained. This pilot study explored the achieved oxygenation patterns observed when targeting SpO2 92-97% to facilitate the design of future trials.

DESIGN

Single-centre prospective randomised crossover pilot study. Manual FiO2 adjustment. Study time 12 hours per infant. 6 hours targeting SpO2 90-95% and 6 hours targeting SpO2 92-97%.

PATIENTS

Twenty preterm infants born <29 weeks' gestation, greater than 48 hours old, receiving supplemental oxygen.

OUTCOMES

Primary outcome was percentage time with SpO2 above 97% and below 90%. Pre-defined secondary outcomes included percentage time spent within, above or below transcutaneous PO2 (TcPO2) 6.7-10.7 kPa (50-80 mm Hg). Comparisons were made using paired-samples t-test (2-tailed).

RESULTS

With SpO2 target 92-97% versus 90-95%, the mean (IQR) percentage time above SpO2 97% was 11.3% (2.7-20.9) versus 7.8% (1.7-13.9), p=0.02. Percentage time with SpO2 <90% was 13.1% (6.7-19.1) versus 17.9% (11.1-22.4), p=0.003. Percentage time with SpO2 <80% was 1% (0.1-1.4) versus 1.6% (0.4-2.6), p=0.119. Percentage time with TcPO2 <6.7 kPa (50 mm Hg) was 49.6% (30.2-66.0) versus 55% (34.3-73.5), p=0.63. Percentage time above TcPO2 10.7 kPa (80 mm Hg) was 1.4% (0-1.4) versus 1.8% (0-0), p=0.746.

CONCLUSIONS

Targeting SpO2 92-97% produced a right shift in SpO2 and TcPO2 distribution, with reduced time at SpO2 <90% and increased time at SpO2 >97%, without increasing time with TcPO2 >10.7 kPa (80 mm Hg). Clinical trials targeting this higher SpO2 range could be conducted without significant hyperoxic exposure.

TRIAL REGISTRATION NUMBER

NCT03360292.

Comparison of two automated oxygen controllers in oxygen targeting in preterm infants during admission: an observational study

OBJECTIVE

To compare the effect of two different automated oxygen control devices on time preterm infants spent in different oxygen saturation (SpO₂) ranges during their entire stay in the neonatal intensive care unit (NICU).

DESIGN

Retrospective cohort study of prospectively collected data.

SETTING

Tertiary level neonatal unit in the Netherlands.

PATIENTS

Preterm infants (OxyGenie 75 infants, CLiO₂ 111 infants) born at 24-29 weeks' gestation receiving at least 72 hours of respiratory support between October 2015 and November 2020.

INTERVENTIONS

Inspired oxygen concentration was titrated by the OxyGenie controller (SLE6000 ventilator) between February 2019 and November 2020 and the CLiO₂ controller (AVEA ventilator) between October 2015 and December 2018 as standard of care.

MAIN OUTCOME MEASURES

Time spent within SpO₂ target range (TR, 91-95% for either epoch) and other SpO₂ ranges.

RESULTS

Time spent within the SpO₂ TR when receiving supplemental oxygen was higher during OxyGenie control (median 71.5 [IQR 64.6-77.0]% vs 51.3 [47.3-58.5]%, p<0.001). Infants under OxyGenie control spent less time in hypoxic and hyperoxic ranges (SpO₂<80%: 0.7 [0.4-1.4]% vs 1.2 [0.7-2.3]%, p<0.001; SpO2>98%: 1.0 [0.5-2.4]% vs 4.0 [2.0-7.9]%, p<0.001). Both groups received a similar FiO₂ (29.5 [28.0-33.2]% vs 29.6 [27.7-32.1]%, p=not significant).

CONCLUSIONS

Oxygen saturation targeting was significantly different in the OxyGenie epoch in preterm infants, with less time in hypoxic and hyperoxic SpO₂ ranges during their stay in the NICU.

Reducing the time delay of oxygen transport to the neonate on continuous positive airway pressure support: A bench study

Background

Premature newborns often require oxygen support as part of their therapy. Systems for oxygen administration are developed to assure adequate oxygenation of newborns. Several factors were identified in the systems that contribute to the time delay between the change in the set inspiratory oxygen fraction and its actual delivery to tissues. In this study, we aimed to reduce the physical delay in oxygen delivery to newborns.

Methods

We developed an O₂ Flush System (O₂-FS) that brings the source of oxygen as close to a patient as possible to make oxygen available for rapid delivery that compensates for the physical delay in the ventilator circuit. The O₂-FS system is built around an electromechanical on/off valve. We validated the O₂-FS concept in experiments with non-invasive Continuous Positive Airways Pressure (CPAP) ventilators.

Results

The O₂-FS accelerated oxygen delivery with all the tested systems and arrangements, typically by 5-15 s. We also observed that the application of supplemental oxygen increased the pressure in the ventilator circuit by 3-4 cmH₂O which may mitigate the apneic pauses that are common in premature newborns.

Conclusions

The O₂-FS system may work as a universal accessory of the CPAP lung ventilator and shorten the distribution of oxygen to the patient during oxygen desaturation events, possibly eliminating or interrupting apneic pauses in neonates, for whom oxygen therapy is an essential treatment. In clinical practice, the O₂-FS could help maintain normoxemic saturation values through adequate oxygen dosing in preterm neonates, thus reducing morbidity and mortality.

Closed–loop oxygen control improves oxygenation in pediatric patients under high–flow nasal oxygen—A randomized crossover study

Background

We assessed the effect of a closed–loop oxygen control system in pediatric patients receiving high–flow nasal oxygen therapy (HFNO).

Methods

A multicentre, single–blinded, randomized, and cross–over study. Patients aged between 1 month and 18 years of age receiving HFNO for acute hypoxemic respiratory failure (AHRF) were randomly assigned to start with a 2–h period of closed–loop oxygen control or a 2–h period of manual oxygen titrations, after which the patient switched to the alternative therapy. The endpoints were the percentage of time spent in predefined SpO2 ranges (primary), FiO2, SpO2/FiO2, and the number of manual adjustments.

Findings

We included 23 patients, aged a median of 18 (3–26) months. Patients spent more time in a predefined optimal SpO2 range when the closed–loop oxygen controller was activated compared to manual oxygen titrations [91⋅3% (IQR 78⋅4–95⋅1%) vs. 63⋅0% (IQR 44⋅4–70⋅7%)], mean difference [28⋅2% (95%–CI 20⋅6–37⋅8%); P &lt; 0.001]. Median FiO2 was lower [33⋅3% (IQR 26⋅6–44⋅6%) vs. 42⋅6% (IQR 33⋅6–49⋅9%); P = 0.07], but median SpO2/FiO2 was higher [289 (IQR 207–348) vs. 194 (IQR 98–317); P = 0.023] with closed–loop oxygen control. The median number of manual adjustments was lower with closed–loop oxygen control [0⋅0 (IQR 0⋅0–0⋅0) vs. 0⋅5 (IQR 0⋅0–1⋅0); P &lt; 0.001].

Conclusion

Closed-loop oxygen control improves oxygenation therapy in pediatric patients receiving HFNO for AHRF and potentially leads to more efficient oxygen use. It reduces the number of manual adjustments, which may translate into decreased workloads of healthcare providers.

Clinical trial registration

[www.ClinicalTrials.gov], identifier [NCT 05032365].

Randomised crossover trial comparing algorithms and averaging times for automatic oxygen control in preterm infants

OBJECTIVE

Automatic control (SPOC) of the fraction of inspired oxygen (FiO₂), based on continuous analysis of pulse oximeter saturation (SpO₂), improves the proportion of time preterm infants spend within a specified SpO₂-target range (Target%). We evaluated if a revised SPOC algorithm (SPOC_new, including an upper limit for FiO₂) compared to both routine manual control (RMC) and the previously tested algorithm (SPOC_old, unrestricted maximum FiO₂) increases Target%, and evaluated the effect of the pulse oximeter's averaging time on controlling the SpO₂ signal during SPOC periods.

DESIGN

Unblinded, randomised controlled crossover study comparing 2 SPOC algorithms and 2 SpO₂ averaging times in random order: 12 hours SPOC_new and 12 hours SPOC_old (averaging time 2 s or 8 s for 6 hours each) were compared with 6-hour RMC. A generated list of random numbers was used for allocation sequence.

SETTING

University-affiliated tertiary neonatal intensive care unit, Germany PATIENTS: Twenty-four infants on non-invasive respiratory support with FiO₂ >0.21 were analysed (median gestational age at birth, birth weight and age at randomisation were 25.3 weeks, 585 g and 30 days).

MAIN OUTCOME MEASURE

Target%.

RESULTS

Mean (SD) [95% CI] Target% was 56% (9) [52, 59] for RMC versus 69% (9) [65, 72] for SPOC_old__2s, 70% (7) [67, 73] for SPOC_new__2s, 71% (8) [68, 74] for SPOC_old__8s and 72% (8) [69, 75] for SPOC_new__8s.

CONCLUSIONS

Irrespective of SpO₂-averaging time, Target% was higher with both SPOC algorithms compared to RMC. Despite limiting the maximum FiO₂, SPOC_new remained significantly better at maintaining SpO₂ within target range compared to RMC.

TRIAL REGISTRATION

NCT03785899.

Automated Oxygen Delivery in Neonatal Intensive Care

Oxygen is the most common drug used in the neonatal intensive care. It has a narrow therapeutic range in preterm infants. Too high (hyperoxemia) or low oxygen (hypoxemia) is associated with adverse neonatal outcomes. It is not only prudent to maintain oxygen saturations in the target range, but also to avoid extremes of oxygen saturations. In routine practice when done manually by the staff, it is challenging to maintain oxygen saturations within the target range. Automatic control of oxygen delivery is now feasible and has shown to improve the time spent with in the target range of oxygen saturations. In addition, it also helps to avoid extremes of oxygen saturation. However, there are no studies that evaluated the clinical outcomes with automatic control of oxygen delivery. In this narrative review article, we aim to present the current evidence on automatic oxygen control and the future directions.

Automated control of oxygen titration in preterm infants on non-invasive respiratory support

OBJECTIVE

To evaluate the performance of a rapidly responsive adaptive algorithm (VDL1.1) for automated oxygen control in preterm infants with respiratory insufficiency.

DESIGN

Interventional cross-over study of a 24-hour period of automated oxygen control compared with aggregated data from two flanking periods of manual control (12 hours each).

SETTING

Neonatal intensive care unit.

PARTICIPANTS

Preterm infants receiving non-invasive respiratory support and supplemental oxygen; median birth gestation 27 weeks (IQR 26-28) and postnatal age 17 (12-23) days.

INTERVENTION

Automated oxygen titration with the VDL1.1 algorithm, with the incoming SpO₂ signal derived from a standard oximetry probe, and the computed inspired oxygen concentration (FiO₂) adjustments actuated by a motorised blender. The desired SpO₂ range was 90%-94%, with bedside clinicians able to make corrective manual FiO₂ adjustments at all times.

MAIN OUTCOME MEASURES

Target range (TR) time (SpO₂ 90%-94% or 90%-100% if in air), periods of SpO₂ deviation, number of manual FiO₂ adjustments and oxygen requirement were compared between automated and manual control periods.

RESULTS

In 60 cross-over studies in 35 infants, automated oxygen titration resulted in greater TR time (manual 58 (51-64)% vs automated 81 (72-85)%, p<0.001), less time at both extremes of oxygenation and considerably fewer prolonged hypoxaemic and hyperoxaemic episodes. The algorithm functioned effectively in every infant. Manual FiO₂ adjustments were infrequent during automated control (0.11 adjustments/hour), and oxygen requirements were similar (manual 28 (25-32)% and automated 26 (24-32)%, p=0.13).

CONCLUSION

The VDL1.1 algorithm was safe and effective in SpO₂ targeting in preterm infants on non-invasive respiratory support.

TRIAL REGISTRATION NUMBER

ACTRN12616000300471.

Comparison of two devices for automated oxygen control in preterm infants: a randomised crossover trial

OBJECTIVE

To compare the effect of two different automated oxygen control devices on target range (TR) time and occurrence of hypoxaemic and hyperoxaemic episodes.

DESIGN

Randomised cross-over study.

SETTING

Tertiary level neonatal unit in the Netherlands.

PATIENTS

Preterm infants (n=15) born between 24+0 and 29+6 days of gestation, receiving invasive or non-invasive respiratory support with oxygen saturation (SpO₂) TR of 91%-95%. Median gestational age 26 weeks and 4 days (IQR 25 weeks 3 days-27 weeks 6 days) and postnatal age 19 (IQR 17-24) days.

INTERVENTIONS

Inspired oxygen concentration was titrated by the OxyGenie controller (SLE6000 ventilator) and the CLiO₂ controller (AVEA ventilator) for 24 hours each, in a random sequence, with the respiratory support mode kept constant.

MAIN OUTCOME MEASURES

Time spent within set SpO₂ TR (91%-95% with supplemental oxygen and 91%-100% without supplemental oxygen).

RESULTS

Time spent within the SpO₂ TR was higher during OxyGenie control (80.2 (72.6-82.4)% vs 68.5 (56.7-79.3)%, p<0.005). Less time was spent above TR while in supplemental oxygen (6.3 (5.1-9.9)% vs 15.9 (11.5-30.7)%, p<0.005) but more time spent below TR during OxyGenie control (14.7 (11.8%-17.2%) vs 9.3 (8.2-12.6)%, p<0.05). There was no significant difference in time with SpO₂ <80% (0.5 (0.1-1.0)% vs 0.2 (0.1-0.4)%, p=0.061). Long-lasting SpO₂ deviations occurred less frequently during OxyGenie control.

CONCLUSIONS

The OxyGenie control algorithm was more effective in keeping the oxygen saturation within TR and preventing hyperoxaemia and equally effective in preventing hypoxaemia (SpO₂ <80%), although at the cost of a small increase in mild hypoxaemia.

TRIAL REGISTRY NUMBER

NCT03877198.

Automation of oxygen titration in preterm infants: Current evidence and future challenges

For the preterm infant with respiratory insufficiency requiring supplemental oxygen, tight control of oxygen saturation (SpO₂) is advocated, but difficult to achieve in practice. Automated control of oxygen delivery has emerged as a potential solution, with six control algorithms currently embedded in commercially-available respiratory support devices. To date, most clinical evaluations of these algorithms have been short-lived crossover studies, in which a benefit of automated over manual control of oxygen titration has been uniformly noted, along with a reduction in severe SpO₂ deviations and need for manual FiO₂ adjustments. A single non-randomised study has examined the effect of implementation of automated oxygen control with the CLiO₂ algorithm as standard care for preterm infants; no clear benefits in relation to clinical outcomes were noted, although duration of mechanical ventilation was lessened. The results of randomised controlled trials are awaited. Beyond the gathering of evidence regarding a treatment effect, we contend that there is a need for a better understanding of the function of contemporary control algorithms under a range of clinical conditions, further exploration of techniques of adaptation to individualise algorithm performance, and a concerted effort to apply this technology in low resource settings in which the majority of preterm infants receive care. Attainment of these goals will be paramount in optimisation of oxygen therapy for preterm infants globally.

Predictive Intelligent Control of Oxygenation (PRICO) in preterm infants on high flow nasal cannula support: a randomised cross-over study

OBJECTIVE

To investigate the efficacy of automated control of inspired oxygen (FiO2) by Predictive Intelligent Control of Oxygenation (PRICO) on the Fabian ventilator in maintaining oxygen saturation (SpO2) in preterm infants on high flow nasal cannula (HFNC) support.

DESIGN

Single-centre randomised two-period crossover study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

27 preterm infants (gestational age (GA) <30 weeks) on HFNC support with FiO2 >0.25.

INTERVENTION

A 24-hour period on automated FiO2-control with PRICO compared with a 24-hour period on routine manual control (RMC) to maintain a SpO2 level within target range of 88%-95% measured at 30 s intervals.

MAIN OUTCOME MEASURES

Primary outcome: time spent within target range (88%-95%).

SECONDARY OUTCOMES

time spent above and below target range, in severe hypoxia (SpO2 <80%) and hyperoxia (SpO2 >98%), mean SpO2 and FiO2 and manual FiO2 adjustments.

RESULTS

15 patients received PRICO-RMC and 12 RMC-PRICO. The mean time within the target range increased with PRICO: 10.8% (95% CI 7.6 to 13.9). There was a decrease in time below target range: 7.6% (95% CI 4.2 to 11.0), above target range: 3.1% (95% CI 2.9 to 6.2) and in severe hypoxia: 0.9% (95% CI 1.5 to 0.2). We found no difference in time spent in severe hyperoxia. Mean FiO2 was higher during PRICO: 0.019 (95% CI 0.006 to 0.030). With PRICO there was a reduction of manual adjustments: 9/24 hours (95% CI 6 to 12).

CONCLUSION

In preterm infants on HFNC support, automated FiO2-control by PRICO is superior to RMC in maintaining SpO2 within target range. Further validation studies with a higher sample frequency and different ventilation modes are needed.

Automated versus manual oxygen control in preterm infants receiving respiratory support: a systematic review and meta-analysis

BACKGROUND

Ventilated preterm infants are exposed to deviations from the intended arterial oxygen saturation range. Therefore, an automated control system was developed to rapidly modulate the fraction of inspired oxygen. The aim of this review is to compare the efficacy and safety of automated versus manual oxygen delivery control.

METHODS

In December 2020, we systematically searched four electronic databases; PubMed, Cochrane Library, Scopus, and Web of Science for eligible randomized controlled trials. We extracted and pooled data as mean difference and 95% confidence interval in an inverse variance method using RevMan software.

RESULTS

Thirteen trials were included in this systematic review and meta-analysis, enrolling 343 preterm infants on respiratory support. Automated oxygen control increased the time spent within the target arterial oxygen saturation range of 85-96% (MD = 8.96; 95% CI [6.26, 11.67], p<.00001), and 90-95% (MD = 18.25; 95% CI [4.58, 31.65], p = .008). In addition, it reduced the time of hypoxia (<80%); (MD = -1.24; 95% CI [-2.05, -0.43], p = .003), (MD = -0.82; 95% CI [-1.23, -0.41], p<.0001) with predetermined ranges of 85-96% and 90-95%, respectively. Automated control system reduced as well the time of hyperoxia (>98%) (MD = -0.99; 95% CI [-1.74, -0.25], p = .009) at intended range of 90-95%, and number of manual inspired oxygen fraction adjustments (MD = -2.82; 95% CI [-4.56, -1.08], p = .002).

CONCLUSIONS

Automated oxygen delivery is rapid and effective in controlling infants' oxygen saturation. It can be used to reduce the load over the nurses, but not to substitute the clinical supervision. Further long-term trials of large-scale are required to evaluate the prolonged clinical outcomes.

Automated control of fraction of inspired oxygen: is it time for widespread adoption?

PURPOSE OF REVIEW

Over the past two decades, numerous algorithms for automated control of the fraction of inspired oxygen (FiO2) have been developed and incorporated into contemporary neonatal ventilators and high-flow devices in an attempt to optimize supplemental oxygen therapy in preterm infants. This review explores whether current evidence is sufficient to recommend widespread adoption of automated oxygen control in neonatal care.

RECENT FINDINGS

To date, 15 studies have compared automated versus manual control of FiO2 in preterm infants on respiratory support. This includes four new randomized cross-over trials published in the last 2 years. Available evidence consistently demonstrates a significant improvement in time spent within the target saturation range with automated FiO2 control. There are fewer episodes of severe hypoxemia and fewer manual FiO2 adjustments with automated oxygen control. Nursing workload may be reduced. However, no currently completed studies report on clinical outcomes, such as chronic lung disease or retinopathy of prematurity.

SUMMARY

Automated oxygen control appears to be a reasonable option for FiO2 titration in preterm infants on respiratory support, if resources are available, and might substantially reduce nursing workload. Further randomized clinical trials to explore its effects on clinical outcomes are required.

Automated oxygen control in preterm infants, how does it work and what to expect: a narrative review

BACKGROUND

Automated oxygen control systems are finding their way into contemporary ventilators for preterm infants, each with its own algorithm, strategy and effect.

OBJECTIVE

To provide guidance to clinicians seeking to comprehend automated oxygen control and possibly introduce this technology in their practice.

METHOD

A narrative review of the commercially available devices using different algorithms incorporating rule-based, proportional-integral-derivative and adaptive concepts are described and explained. An overview of how they work and, if available, the clinical effect is given.

RESULTS

All algorithms have shown a beneficial effect on the proportion of time that oxygen saturation is within target range, and a decrease in hyperoxia and severe hypoxia. Automated oxygen control may also reduce the workload for bedside staff. There is concern that such devices could mask clinical deterioration, however this has not been reported to date.

CONCLUSIONS

So far, trials involving different algorithms are heterogenous in design and no head-to-head comparisons have been made, making it difficult to differentiate which algorithm is most effective and what clinicians can expect from algorithms under certain conditions.

A randomised crossover trial of closed loop automated oxygen control in preterm, ventilated infants

AIM

To determine whether closed loop automated oxygen control resulted in a reduction in the duration and severity of desaturation episodes and the number of blood gases and chest radiographs in preterm, ventilated infants.

METHODS

Infants were studied on two consecutive days for 12 hours on each day. They were randomised to receive standard care (standard period) or standard care with a closed loop automated oxygen control system (automated oxygen control period) first.

RESULTS

Twenty-four infants with a median gestational age of 25.7 (range 23.1-32.6) weeks were studied at a median postconceptional age of 27.4 (range 24.3-34.9) weeks. During the automated oxygen control period, there were fewer desaturations that lasted >30 seconds (P = .032) or >60 seconds (P = .002), infants spent a higher proportion of the time within their target SpO₂ range during the automated oxygen control period (P < .001), and fewer manual adjustments were made to the inspired oxygen concentration (mean 0.58 vs mean 11.29) (P < .001). There were no significant differences in the number of blood gases (P = .872) or chest radiographs (P = .366) between the two periods.

CONCLUSION

Closed loop automated oxygen delivery resulted in fewer prolonged desaturations with more time spent in the targeted oxygen range.

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.