OBJECTIVE: Changes in oximeter averaging times have been noted to affect alarm settings. Automated algorithms (A-FiO2) assess FiO2 faster than oximeter averaging, potentially impacting their effectiveness. METHODS: In a single NICU routinely using 15 fabian-PRICO A-FiO2 systems, neonates were randomly exposed to SpO2 averaging time settings switched every 12 h among short (2-4 s), medium (10 s), and long (16 s) oximeter averaging times for the entire duration of their A-FiO2 exposure. Primary endpoints were the percent time in the set SpO2 target range (dependent on PMA), SpO2 < 80%, and SpO2 > 98%, excluding FiO2 = 0.21. RESULTS: Ten VLBW neonates were enrolled over 11 months. At entry, they were 17 days old (IQR: 14-19), with an adjusted gestational age of 29 weeks (IQR: 27-30). The study included data from 272 days of A-FiO2 control (34% short, 32% medium, and 34% long). Respiratory support was predominantly non-invasive (53% NCPAP, 40% HFNC, and 6% NIPPV). The aggregate SpO2 exposure levels were 67% (IQR: 55-82) in the target range, 5.4% (IQR: 2.0-10) with SpO2 < 80%, and 1.2% (IQR: 0.4-3.1) with SpO2 > 98%. There were no differences in the target range time between the SpO2 averaging time settings. There were differences at the SpO2 extremes (p ≤ 0.001). The medium and long averaging were both lower than the short, with the difference larger than predicted. Multivariate analysis revealed that these findings were independent of subject, ventilation mode, target range, and overall stability. CONCLUSIONS: This A-FiO2 algorithm is effective regardless of the SpO2 averaging time setting. There is an advantage to the longer settings, which suggest an interaction with the controller.

• Klíčová slova
• SpO2 targeting, automated oxygen control, neonatal, oxygen control, pulse oximetry,
• Publikační typ
• časopisecké články MeSH

The reliability of pulse oximetry is crucial, especially in cases of rapid changes in body oxygenation. In order to evaluate the performance of pulse oximeters during rapidly developing short periods of concurrent hypoxemia and hypercapnia, 13 healthy volunteers underwent 3 breathing phases during outdoor experiments (39 phases in total), monitored simultaneously by five different pulse oximeters. A significant incongruity in values displayed by the tested pulse oximeters was observed, even when the accuracy declared by the manufacturers were considered. In 28.2% of breathing phases, the five used devices did not show any congruent values. The longest uninterrupted congruent period formed 74.4% of total recorded time. Moreover, the congruent periods were rarely observed during the critical desaturation phase of the experiment. The time difference between the moments when the first and the last pulse oximeter showed the typical study endpoint values of SpO2 85% and 75% was 32.1 ± 23.6 s and 24.7 ± 19.3 s, respectively. These results suggest that SpO2 might not be a reliable parameter as a study endpoint, or more importantly as a safety limit in outdoor experiments. In the design of future studies, more parameters and continuous clinical assessment should be included.

• Klíčová slova
• avalanche victim, hypoxemia, outdoor experiments, oxygen saturation, pulse oximetry, safety limits,
• MeSH
• hypoxie diagnóza   MeSH
• kyslík * MeSH
• lidé MeSH
• monitorování fyziologických funkcí MeSH
• oxymetrie * MeSH
• reprodukovatelnost výsledků MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyslík * MeSH

BACKGROUND: Continuous monitoring of SpO2 in the neonatal ICU is the standard of care. Changes in SpO2 exposure have been shown to markedly impact outcome, but limiting extreme episodes is an arduous task. Much more complicated than setting alarm policy, it is fraught with balancing alarm fatigue and compliance. Information on optimum strategies is limited. METHODS: This is a retrospective observational study intended to describe the relative chance of normoxemia, and risks of hypoxemia and hyperoxemia at relevant SpO2 levels in the neonatal ICU. The data, paired SpO2-PaO2 and post-menstrual age, are from a single tertiary care unit. They reflect all infants receiving supplemental oxygen and mechanical ventilation during a 3-year period. The primary measures were the chance of normoxemia (PaO2 50-80 mmHg), risks of severe hypoxemia (PaO2 ≤ 40 mmHg), and of severe hyperoxemia (PaO2 ≥ 100 mmHg) at relevant SpO2 levels. RESULTS: Neonates were categorized by postmenstrual age: < 33 (n = 155), 33-36 (n = 192) and > 36 (n = 1031) weeks. From these infants, 26,162 SpO2-PaO2 pairs were evaluated. The post-menstrual weeks (median and IQR) of the three groups were: 26 (24-28) n = 2603; 34 (33-35) n = 2501; and 38 (37-39) n = 21,058. The chance of normoxemia (65, 95%-CI 64-67%) was similar across the SpO2 range of 88-95%, and independent of PMA. The increasing risk of severe hypoxemia became marked at a SpO2 of 85% (25, 95%-CI 21-29%), and was independent of PMA. The risk of severe hyperoxemia was dependent on PMA. For infants < 33 weeks it was marked at 98% SpO2 (25, 95%-CI 18-33%), for infants 33-36 weeks at 97% SpO2 (24, 95%-CI 14-25%) and for those > 36 weeks at 96% SpO2 (20, 95%-CI 17-22%). CONCLUSIONS: The risk of hyperoxemia and hypoxemia increases exponentially as SpO2 moves towards extremes. Postmenstrual age influences the threshold at which the risk of hyperoxemia became pronounced, but not the thresholds of hypoxemia or normoxemia. The thresholds at which a marked change in the risk of hyperoxemia and hypoxemia occur can be used to guide the setting of alarm thresholds. Optimal management of neonatal oxygen saturation must take into account concerns of alarm fatigue, staffing levels, and FiO2 titration practices.

• Klíčová slova
• Alarm fatigue, Neonatology, Pulse oximetry,
• MeSH
• analýza krevních plynů MeSH
• hypoxie diagnóza   etiologie   MeSH
• jednotky intenzivní péče o novorozence * MeSH
• kojenec MeSH
• kyslík * MeSH
• lidé MeSH
• novorozenec MeSH
• oxymetrie MeSH
• Check Tag
• kojenec MeSH
• lidé MeSH
• novorozenec MeSH
• Publikační typ
• časopisecké články MeSH
• pozorovací studie MeSH
• Názvy látek
• kyslík * MeSH

BACKGROUND: Changes in oxygen saturation (SpO2) exposure have been shown to have a marked impact on neonatal outcomes and therefore careful titration of inspired oxygen is essential. In routine use, however, the frequency of SpO2 alarms not requiring intervention results in alarm fatigue and its corresponding risk. SpO2 control systems that automate oxygen adjustments (Auto-FiO2) have been shown to be safe and effective. We speculated that when using Auto-FiO2, alarm settings could be refined to reduce unnecessary alarms, without compromising safety. METHODS: An unblinded randomized crossover study was conducted in a single NICU among infants routinely managed with Auto-FiO2. During the first 6 days of respiratory support a tight and a loose alarm strategy were switched each 24 h. A balanced block randomization was used. The tight strategy set the alarms at the prescribed SpO2 target range, with a 30-s delay. The loose strategy set the alarms 2 wider, with a 90-s delay. The effectiveness outcome was the frequency of SpO2 alarms, and the safety outcomes were time at SpO2 extremes (< 80, > 98%). We hypothesized that the loose strategy would result in a marked decrease in the frequency of SpO2 alarms, and no increases at SpO2 extremes with 20 subjects. Within subject differences between alarm strategies for the primary outcomes were evaluated with Wilcoxon signed-rank test. RESULTS: During a 13-month period 26 neonates were randomized. The analysis included 21 subjects with 49 days of both tight and loose intervention. The loose alarm strategy resulted in a reduction in the median rate of SpO2 alarms from 5.2 to 1.6 per hour (p < 0.001, 95%-CI difference 1.6-3.7). The incidence of hypoxemia and hyperoxemia were very low (less than 0.1%-time) with no difference associated with the alarm strategy (95%-CI difference less than 0.0-0.2%). CONCLUSIONS: In this group of infants we found a marked advantage of the looser alarm strategy. We conclude that the paradigms of alarm strategies used for manual titration of oxygen need to be reconsidered when using Auto-FiO2. We speculate that with optimal settings false positive SpO2 alarms can be minimized, with better vigilance of clinically relevant alarms. TRIAL REGISTRATION: Retrospectively registered 15 May 2018 at ISRCTN ( 49239883 ).

• Klíčová slova
• Alarm fatigue, Automated oxygen control, Oxygen saturation,
• MeSH
• automatizace MeSH
• hypoxie prevence a kontrola   MeSH
• jednotky intenzivní péče o novorozence MeSH
• klinické alarmy * MeSH
• klinické křížové studie MeSH
• lidé MeSH
• monitorování fyziologických funkcí MeSH
• nemocnice veřejné MeSH
• novorozenec nedonošený * MeSH
• novorozenec MeSH
• oxygenoterapie metody   MeSH
• oxymetrie MeSH
• péče o pacienty v kritickém stavu metody   MeSH
• prognóza MeSH
• spotřeba kyslíku fyziologie   MeSH
• umělé dýchání metody   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH
• Geografické názvy
• Polsko MeSH