Elsevier

Resuscitation

Volume 136, March 2019, Pages 100-104
Resuscitation

Clinical paper
Time to achieve desired fraction of inspired oxygen using a T-piece ventilator during resuscitation of preterm infants at birth

https://doi.org/10.1016/j.resuscitation.2019.01.024Get rights and content

Abstract

Aim

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.

Methods

This observational study was performed using a Neopuff™ T-piece Resuscitator attached to either a test lung (during initial bench tests) or a face mask during the stabilization of infants at birth. FiO2 was titrated following resuscitation guidelines. The duration for the desired FiO2 to reach either the test lung or face mask was recorded, both with and without leakage. A respiratory function monitor was used to record FiO2 and amount of leak.

Results

In bench tests, the median (IQR) time taken to achieve a desired FiO2 was 34.2 (21.8–69.1) s. This duration was positively associated with the desired FiO2 difference, the direction of titration (upwards) and the occurrence of no leak (R2 0.863, F 65.016, p < 0.001). During stabilization of infants (median (IQR) gestational age 29+0 (28+2–30+0) weeks, birthweight 1290 (1240–1488) g), the duration (19.0 (0.0–57.0) s) required to reach a desired FiO2 was less, but still evident. In 27/55 (49%) titrations, the desired FiO2 was not achieved before the FiO2 levels were again changed.

Conclusion

There is a clear delay before a desired FiO2 is achieved at the distal end of the T-piece resuscitator. This delay is clinically relevant as this delay could easily lead to over- and under titration of oxygen, which might result in an increased risk for both hypoxia and hyperoxia.

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.

References (14)

There are more references available in the full text version of this article.

Cited by (11)

  • The quest for optimum oxygenation during newborn delivery room resuscitation: Is it the baby or is it us?

    2022, Seminars in Perinatology
    Citation 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 Medicine
    Citation 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, Resuscitation
    Citation 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 Medicine
    Citation 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.

View all citing articles on Scopus
View full text