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

Fluctuations in Oxygen Saturation during Synchronized Nasal Intermittent Positive Pressure Ventilation and Nasal High-Frequency Oscillatory Ventilation in Very Low Birth Weight Infants: A Randomized Crossover Trial

BACKGROUND

Very low birth weight (VLBW) infants on noninvasive ventilation (NIV) experience frequent fluctuations in oxygen saturation (SpO2) that are associated with an increased risk for mortality and severe morbidities.

METHODS

In this randomized crossover trial, VLBW infants (n = 22) born 22+3 to 28+0 weeks on NIV with supplemental oxygen were allocated on two consecutive days in random order to synchronized nasal intermittent positive pressure ventilation (sNIPPV) and nasal high-frequency oscillatory ventilation (nHFOV) for 8 h. nHFOV and sNIPPV were set to equivalent mean airway pressure and transcutaneous pCO2. Primary outcome was the time spent within the SpO2 target (88-95%).

RESULTS

During sNIPPV, VLBW infants spent significantly more time within the SpO2 target (59.9%) than during nHFOV (54.6%). The proportion of time spent in hypoxemia (22.3% vs. 27.1%) and the mean fraction of supplemental oxygen (FiO2) (29.4% vs. 32.8%) were significantly reduced during sNIPPV, while the respiratory rate (50.1 vs. 42.6) was significantly higher. Mean SpO2, SpO2 above the target, number of prolonged (>1 min) and severe (SpO2 <80%) hypoxemic episodes, parameters of cerebral tissue oxygenation using NIRS, number of FiO2 adjustments, heart rate, number of bradycardias, abdominal distension and transcutaneous pCO2 did not differ between both interventions.

CONCLUSIONS

In VLBW infants with frequent fluctuations in SpO2, sNIPPV is more efficient than nHFOV to retain the SpO2 target and to reduce FiO2 exposure. These results demand more detailed investigations into cumulative oxygen toxicities during different modes of NIV over the weaning period, particularly with regard to consequences for long-term outcomes.

Pulse Oximetry Saturation (Spo2) Monitoring in the Neonatal Intensive Care Unit (NICU): The Challenge for Providers: A Systematic Review

BACKGROUND

In the neonatal intensive care unit (NICU), maintaining an oxygenation level that avoids both hypoxemia and hyperoxemia is challenging. Pulse oximetry has become fundamental for noninvasive monitoring of saturation of peripheral oxygen (Spo2) in preterm newborns.

PURPOSE

The aim of this systematic review is to determine Spo2 target values in order to avoid hypoxemia or hyperoxemia and complications arising from these.

METHOD AND SEARCH STRATEGY

For this systematic review, articles were audited from 2010 to 2020 using the PRISMA guidelines. PubMed, MEDLINE, Google Scholar, and Scopus databases were used, and search terms were related to use of pulse oximetry in the NICU.

RESULTS

The result showed that 12 of 20 (60%) studies focused on target values but without a unanimous agreement on values, although 5 of 12 studies (41.66%) suggested a lower value target of 85% and 4 of 12 studies (33.33%) recommended 95% as the higher target value. Other authors showed no difference in the incidence of adverse events comparing different target values and focused the importance more on the fluctuation of the value than on the target value itself.

IMPLICATION FOR PRACTICE

Reaching a balance in the oxygen administration so as to avoid potential complications associated with hypoxemia or hyperoxemia is a challenge for the clinicians.

IMPLICATION FOR RESEARCH

Further studies on fluctuation of Spo2 comparing different starting targets could better clarify the role of fluctuations and the absolute target values.Video Abstract available at:https://journals.na.lww.com/advancesinneonatalcare/Pages/videogallery.aspx?autoPlay=false&videoId=49.

Eligibility Criteria and Representativeness of Randomized Clinical Trials That Include Infants Born Extremely Premature: A Systematic Review

OBJECTIVE

To assess the eligibility criteria and trial characteristics among contemporary (2010-2019) randomized clinical trials (RCTs) that included infants born extremely preterm (<28 weeks of gestation) and to evaluate whether eligibility criteria result in underrepresentation of high-risk subgroups (eg, infants born at <24 weeks of gestation).

STUDY DESIGN

PubMed and Scopus were searched January 1, 2010, to December 31, 2019, with no language restrictions. RCTs with mean or median gestational ages at birth of <28 weeks of gestation were included. The study followed the PRISMA guidelines; outcomes were registered prospectively. Data extraction was performed independently by multiple observers. Study quality was evaluated using a modified Jadad scale.

RESULTS

Among RCTs (n = 201), 32 552 infants were included. Study participant characteristics, interventions, and outcomes were highly variable. A total of 1603 eligibility criteria were identified; rationales were provided for 18.8% (n = 301) of criteria. Fifty-five RCTs (27.4%) included infants <24 weeks of gestation; 454 (1.4%) infants were identified as <24 weeks of gestation.

CONCLUSIONS

The present study identifies sources of variability across RCTs that included infants born extremely preterm and reinforces the critical need for consistent and transparent policies governing eligibility criteria.

Feed-related Splanchnic Oxygenation in Preterm Infants With Abnormal Antenatal Doppler Developing Gut Complications

Preterm infants with antenatal absent or reversed end diastolic flow (AREDF) in umbilical arteries are at major risk for gastrointestinal (GI) complications, such as necrotizing enterocolitis, intestinal perforation and feeding intolerance. Near-infrared spectroscopy provides continuous monitoring of splanchnic oxygenation (SrSO2) and may represent a useful tool to predict GI outcomes in this high-risk population. This observational, pilot study assessed feed-related SrSO2 patterns at enteral feeding introduction and full enteral feeding (FEF) achievement in twenty AREDF infants with gestational age ≤34 weeks. Enrolled infants were divided into 2 groups according to the development versus lack of GI complications. Infants developing GI complications showed significantly lower SrSO2 and increased splanchnic oxygen extraction in response to enteral feeds at both enteral feeding introduction and FEF. The potential role of these findings in predicting GI complications in AREDF preterm infants seems promising and deserves further evaluation.

The effect of skin-to-skin care on cerebral oxygenation during nasogastric feeding of preterm infants

AIM

To describe cerebral oxygenation during gavage feeding of preterm infants during incubator and skin-to-skin care.

METHODS

Further analysis of data from two crossover studies comparing cerebral oxygenation, heart rate and oxygen saturation during skin-to-skin care with incubator care. Data were analysed in three epochs; 10 minutes prefeed, during-feed and 10 minutes postfeed. Measurements from infants fed during incubator care were compared with those obtained during skin-to-skin care.

RESULTS

In 39 infants [median (IQR) 27.8 (26.1-30.0) weeks' gestation], there was no difference in cerebral oxygenation between pre-, during- and postfeed. Heart rate increased by three beats per minute postfeed compared with during-feed. Twenty infants received two gavage feeds, one feed in the incubator and another during skin-to-skin care. There was no difference in cerebral oxygenation and heart rate; peripheral oxygen saturation decreased by 3% during feeding whilst skin-to-skin care compared with feeding in the incubator.

CONCLUSION

Cerebral oxygenation remained stable before, during and after gavage feeding in an incubator and during skin-to-skin care. The small decrease in oxygen saturation whilst receiving gavage feeding during skin-to-skin care is unlikely to be clinically important, providing reassurance that preterm infants maintain physiological stability during skin-to-skin care.

Cerebral oxygenation and desaturations in preterm infants - a longitudinal data analysis

OBJECTIVE

Hypoxemic episodes commonly occur in very preterm infants and may be associated with several adverse effects. Cerebral tissue oxygen saturation (StO2) as measured by near infrared spectroscopy (NIRS) may be a useful measure to assess brain oxygenation. However, knowledge on variability of StO2 is limited in preterm infants at this time, so StO2 dependency on arterial oxygenation (SpO2) and heart rate (HR) was assessed in preterm infants using statistical methods of time series analysis.

STUDY DESIGN

StO2, SpO2, and HR were recorded from 15 preterm infants every 2 seconds for six hours. Statistical methods of time series and longitudinal data analysis were applied to the data.

RESULT

The mean StO2 level was found as 72% (95% confidence interval (CI) 55.5% -85.5%) based on a moving average process with a 5 minute order. Accordingly, longitudinal SpO2 measurements showed a mean level of 91% (95% CI 69% -98%). Generally, compensation strategies to cope with both StO2 and SpO2 desaturations were observed in the studied patients. SpO2 had a significant effect on cerebral oxygenation (p < 0.001), but HR did not, which led to inconclusive results considering different time intervals.

CONCLUSION

In infants with intermittent hypoxemia and bradycardia, we found a mean StO2 level of 72% and a strong correlation with SpO2. We observed large differences between individuals in the ability to maintain StO2 at a stable level.

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

OBJECTIVE

The 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/SETTING

PubMed, 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.

RESULTS

While 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.

CONCLUSIONS

SUPPORT 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 profile of term equivalent extreme preterm infants at discharge - comparison with healthy term counterparts

AIM

Compare the oxygen saturation profiles before discharge of neonates born extremely preterm (<28 weeks), now at term equivalent age, with healthy term neonates and assess the impact of feeding on this profile in each group.

METHODS

We prospectively evaluated and compared the oxygen saturation profile in 15 very low birthweight infants at term equivalent age, ready to be discharged home without any oxygen and 15 term newborns after 48 hours of life. We also evaluated and compared the saturations of these two groups during a one-hour period during and after feeding.

RESULTS

Term equivalent preterm and term infants spent median 3% and 0%, respectively, of the time below 90% in a 12-hour saturation-recording period. Term infants spent a median 0.26% and 0.65% of the time in <90% saturation during feed time and no feed time, respectively. In contrast, preterm infants spent significantly more time <90% saturation (3.47% and 3.5% during feed time and no feed time, respectively).

CONCLUSION

Term equivalent preterm infants spent significantly more time in a saturation range <90% compared to term infants. Feeding had little effect on saturation profile overall within each group.

Alteration in regional tissue oxygenation of preterm infants during placement in the semi-upright seating position

We investigated whether the cerebral (rSO2-C %) and renal (rSO2-R %) tissue oxygenation of preterm infants is altered by repositioning from the supine to semi-upright position for pre-discharge car seat testing. Near-infrared spectroscopy was used to measure rSO2-C and rSO2-R, which were recorded simultaneously with vital signs in 15 preterm infants for 30 minutes in supine, 60 minutes in the semi-upright (at 45 degrees in a car seat), and 30 minutes in the post-semi-upright (supine) position. Changes in rSO2-C and SO2-R were mostly within 1 Standard Deviation (SD) of baseline mean levels in the supine position. Decrease in rSO2-C and rSO2-R (more than 1SD below baseline mean) was recorded in 26.7% and 6.6% of infants respectively, which persisted even after adjustment for variation in heart and respiratory rate, and pulse oximeter measured oxygen saturation (P, 0.0001). Re-positioning the infants from the car seat to supine position was associated with normalization of the rSO2-C. Alteration in rSO2-C and rSO2-R in a car seat was independent from the gestational and post-conception age, weight and presence of anemia. We concluded that approximately one-third of preterm infants show minor reduction of cerebral tissue oxygenation in the semi-upright (car seat) position.

Effects of automated adjustment of the inspired oxygen on fluctuations of arterial and regional cerebral tissue oxygenation in preterm infants with frequent desaturations

OBJECTIVE

To assess the effect of automated adjustment of the inspired oxygen fraction (FiO2) on arterial oxygen saturation (SpO2) and cerebral tissue oxygen saturation (SctO2) in very low birth weight infants with frequent fluctuations in oxygenation.

STUDY DESIGN

Fifteen infants (median gestational age, 25 weeks [range, 23-28 weeks]; median age, 34 days [range, 19-74 days]) were assigned in random sequence to 24 hours of automated adjustment of FiO2 or manual adjustment of FiO2. Primary outcome measurements were time within the SpO2 target range and the area under the curve above and below a defined SctO2 range.

RESULTS

Percentage of time within the SpO2 target range increased during automated FiO2 control (76.3% ± 9.2% vs 69.1% ± 8.2% for manual; P < .01). Prolonged episodes with SpO2 <88% of >60 seconds duration (median, 115 episodes [range, 67-240] vs 54 episodes [range, 7-184]; P < .01) and of >180 seconds duration (median, 13 episodes [range, 6-39] vs 2 episodes [range, 0-5]; P < .01) decreased significantly during the automated period. Percentage of time with SpO2 >96% decreased during automated control (6.6% ± 4.4% vs 10.4% ± 3.3%; P < .02). There was no significant difference in FiO2 exposure. The area (deviation × time) below and above the defined SctO2 threshold did not differ between the 2 periods (median, 59.7%*seconds [range, 17.2%-208.3%] for manual vs 49.0%*seconds [range, 4.3%-193.7%] for automated; P = .36).

CONCLUSION

Automated FiO2 control in preterm infants with frequent SpO2 fluctuations significantly increased the time within the SpO2 target range and reduced the incidence of prolonged hypoxemic events compared with manual FiO2 adjustment, but did not significantly affect cerebral tissue oxygenation.

Cerebral oxygenation during intermittent hypoxemia and bradycardia in preterm infants

BACKGROUND

Episodes of hypoxemia and bradycardia frequently occur with apnea of prematurity in preterm infants. Little is known about the impact of different event types on the brain.

OBJECTIVES

To describe the influence of hypoxemia and bradycardia, either isolated or in combination, on cerebral oxygenation.

METHODS

In 16 preterm infants with intermittent hypoxemia and/or bradycardia, cerebral tissue oxygen saturation (StO2, as measured by near-infrared spectroscopy), heart rate and pulse oximetric saturation (SpO2) were recorded simultaneously for 16 h. Events were classified as isolated bradycardia (type 1), isolated hypoxemia (type 2) or combined (simultaneous, type 3; bradycardia first, type 4; hypoxemia first, type 5). Primary outcome was a score representing the area below baseline for cerebral StO2 desaturation during an event. Secondary outcomes were duration and depth of cerebral desaturation.

RESULTS

Patients had a median (range) gestational age of 25.9 (22.6-30.4) weeks and a postnatal age of 32.5 (7-58) days. The median (quartiles) number of events was 49 (34-58). Isolated hypoxemias were the most frequent events (24; 9-36) and isolated bradycardias the least common (0; 0-1). Cerebral StO2 baseline was not different between event types. Cerebral desaturation score, duration of event and depth of cerebral desaturation were smallest for isolated bradycardias and largest for combined events, especially for those starting with hypoxemia followed by bradycardia. Regardless of event type, 12/16 infants maintained cerebral StO2 >60% despite severe SpO2 desaturations.

CONCLUSIONS

Isolated bradycardias had the lowest impact on cerebral desaturation, and combined events had the highest. Most infants preserved cerebral oxygenation >60% during events.