Clinical paperTime to achieve desired fraction of inspired oxygen using a T-piece ventilator during resuscitation of preterm infants at birth
Introduction
The transition to life after birth is hampered in preterm infants due to the immature respiratory system expressed by poor compliance of the lungs, weakness of the respiratory muscles and an immature respiratory center with a weak respiratory drive1. Most preterm infants need respiratory support after birth to aerate their lungs and gain adequate oxygenation2. A T-piece ventilator that administers Continuous Positive Airway Pressure (CPAP) or Positive Pressure Ventilation (PPV) via face mask is currently the method of first choice in order to minimize lung injury2, 3, 4. Additional oxygen is often used to reach and maintain adequate oxygenation5.
During stabilization after birth, additional oxygen needs to be titrated based on recommended oxygen saturations (SpO2) to decrease the risk of hypoxia and hyperoxia3, 6. Hypoxia may lead to delayed cellular damage, as during hypoxia the production of free radicals will be provoked by an elevated level of hypoxanthine7, 8. On the other hand, free radical production (associated with both oxidative and nitrosative stress) also increases during hyperoxia, which can overwhelm the relatively immature antioxidant capacity of the preterm infant9, 10, 11, 12. The excess of free radicals in turn may cause wide-spread damage to cells, enzymes, lipids, DNA and proteins9, 10, 11, 12.
A time-dependent oxygen saturation range is targeted during stabilization, that is based on previously described international normograms6. To achieve oxygen saturations in this range, neonatal resuscitation guidelines recommend commencing resuscitation with a fraction of inspired oxygen (FiO2) of 0.21–0.33. The desired oxygen concentration is achieved by mixing oxygen and room air using an oxygen blender, from which the gas mixture is administered to the neonate via the T-piece ventilator. During stabilization after birth, infants are evaluated every 30 s, which guides the amount of support and titration of additional oxygen3. The study of Goos et al. showed that the concentration of oxygen needed during stabilization at birth is highly variable between infants, with a reported range of 0.21–0.99, with 7 (3–10) adjustments of FiO25.
While the adjustment of FiO2 is performed at the oxygen blender, this is located upstream of the T-piece resuscitation device and simply alters the concentration of oxygen entering the device. However, it is unknown how long it takes for the gas mixture with the desired oxygen concentration to reach the infant at the distal part of the circuit. As such, further titration could take place before the original desired FiO2 of gas entering the infant has been achieved. This, in turn, could lead to an increased risk of hypoxia or hyperoxia.
The aim of this study was therefore to determine the time between adjustment of FiO2 at the oxygen blender and the desired FiO2 reaching the preterm infant during respiratory support at birth.
Section snippets
Methods
An observational study was conducted at the Neonatal Intensive Care Unit (NICU) of the Leiden University Medical Center. The study consisted of two parts: a bench test and clinical observations of neonatal stabilization at birth.
The resuscitation of preterm infants at birth was replicated during a bench test, using a Neopuff™ T-piece Resuscitator (Fisher & Paykel Healthcare, Auckland, New Zealand) attached to a 50 mL test lung (Dräger, Lübeck, Germany). The circuit was set up with a flow of
Bench test
When adjusting the FiO2, the oxygen analyser at the proximal part of the circuit reached the desired oxygen concentration within 3 ± 1 s, independent of the amount of leakage in the circuit. There was a delay in time to achieve desired FiO2 at the distal part of the circuit (median (IQR) duration 34.2 (21.8–69.1) s).
Without mask leak, the median (IQR) duration of the FiO2 to reach the desired concentration at the distal part of the Neopuff™ circuit during up-titration was 58.2 (35.7–86.1) s.
Discussion
This study shows a clear delay in obtaining the desired oxygen concentration at the distal part of the Neopuff™ circuit in both the bench test and during stabilization of preterm infants at birth. As the international resuscitation guideline prescribes evaluation periods of 30 s, the clinical evaluation of the infant and physiological parameters might precede the effect of the performed intervention (e.g. titration of oxygen)3. This is demonstrated by the finding that in half of all titration
Conclusion
In summary, there is a clear delay in set up of FiO2 at the proximal part of the T-piece ventilator and achievement of desired FiO2 at the distal part. This delay is clinically relevant when aiming for adequate mask ventilation, whereby over- and under titration of oxygen might result in an increased risk of hypoxia and hyperoxia.
Financial disclosure
The authors have no financial relationships relevant to this article to disclose.
Funding source
Dr. A.B. te Pas is recipient of a NWO innovational research incentives scheme (VIDI 91,716,428).
Conflict of interest statement
The authors have no conflicts of interest relevant to this article to disclose.
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Cited by (11)
The quest for optimum oxygenation during newborn delivery room resuscitation: Is it the baby or is it us?
2022, Seminars in PerinatologyCitation Excerpt :In clinical practice, active manipulation of FiO2 only achieves SpO2 ∼30% of the time.23,24 In bench tests, Dekker et al. found that only 51% of FiO2 titrations achieved desired FiO2 and that each titration took a median of 34.2 (21.8–69.1) s to complete.25 A recent post-hoc analysis comparing two data sets concluded FiO2 titration to reach predetermined SpO2 targets may be just as, or even more important than initial FiO2.26
Technology in the delivery room supporting the neonatal healthcare provider's task
2022, Seminars in Fetal and Neonatal MedicineCitation Excerpt :In addition, the algorithm of the closed-loop oxygen controller should also be calibrated based on the factors present at birth which influence the position of the oxygen-haemoglobin dissociation curve. Furthermore, titration of oxygen using a T-piece ventilator, which is commonly used for respiratory support at birth [14], can result in a delay between the moment of titration and the delivery of the corresponding FiO2 at the face mask of the infant [71]. The algorithm used by the closed-loop oxygen controller that is used with the T-piece resuscitator should therefore reckon with this delay.
European Resuscitation Council Guidelines 2021: Newborn resuscitation and support of transition of infants at birth
2021, ResuscitationCitation Excerpt :A recent review suggested that oxygen delivery should be reviewed and titrated as necessary every 30 s to achieve this.286 An important technical aspect of the titration of supplemental oxygen when using a TPR device is that it takes a median 19 s (IQR 0–57) to achieve the desired oxygen concentration at the distal end of the TPR.287 Although the cause of this delay is unclear, mask leak contributes significantly.
Optimizing oxygen therapy for preterm infants at birth: Are we there yet?
2020, Seminars in Fetal and Neonatal MedicineCitation Excerpt :None of the study protocols dictated a titration strategy, but left to the clinician on how to titrate the Fio2 to achieve target SpO2. Studies have shown that there is a delay between dialed FiO2 on a blender at the proximal end and desired FiO2 at the distal end reaching the infant [62,63]. The delay could be as high as 30 s and it may depend on the device used to deliver oxygen.