Presently oxygen is titrated against saturation (SpO2) by manual adjustment. Automated or
servo-control systems have been developed that result in tighter control of SpO2 and more
time spent in the intended target range. These systems are already in clinical use.
Automated systems produce quite large fluctuations in fraction of inspired oxygen (FiO2)
in order to keep SpO2 in range. It is possible that this could result in short periods of
high or low oxygen tension (PO2) that are undetectable using saturation monitoring.
Studies to date have examined the effects of manual and automated (servo) oxygen
targeting on SpO2 but not on transcutaneous oxygen tension (TcPO2).
Research suggests that individual servo control devices control oxygen effectively as
measured by the readings obtained from their internal SpO2 monitoring system. The device
the investigators intend to study is available with two different oximeter monitoring
systems. When compared to a separate free-standing SpO2 monitor the devices have a
systematic bias in the clinically targeted range. Consequently, this could allow
variations between infants in oxygenation large enough to influence important clinical
outcome to go unrecognised.
There is a need to determine the achieved SpO2 and TcPO2 distributions associated with
the use of different automated control systems as a first step in planning future trials.
When this is measured over a small number of hours it is not anticipated that this would
have an influence on clinical outcome.
This study is a prospective, single centre, randomised crossover trial of two different
internal oximeter monitoring systems in an automated (servo) control device - IntellO2
(Vapotherm, USA) - delivering nasal high flow employing automated oxygen titration. Each
infant will act as their own control. Infants born at less than 30 weeks gestation,
greater than 48 hour of age and receiving supplementary oxygen will be eligible for
inclusion.
The study will be undertaken in the Neonatal Unit at the Simpson Centre for Reproductive
Health at the Royal Infirmary of Edinburgh.
Total study time is 12 hours for each infant. Infants will be randomised to commence on
either Masimo oximetry or Nellcor oximetry using the Oxygen Assist Module (OAM), IntellO2
Vapotherm device. SpO2 (range 90-95%) will be continuously monitored on a second pulse
oximetry probe connected to a bedside multiparameter monitor as per normal standard of
care.
Additional monitoring will be carried out as shown below:
TcPO2 monitoring
FiO2 monitoring
Heart rate monitoring (used to validate SpO2 readings)
Arterial gas sampling (only if conducted by the direct care team as part of the
routine care of the infant; no extra blood samples will be taken as part of the
study)
FiO2 will be adjusted by the respiratory support device which has integrated automated
oxygen control, set to maintain a SpO2 target range of 90-95%.The IntellO2 device uses
Precision Flow technology (IntellO2, Vapotherm, USA). By means of a modified closed-loop
algorithm, the devise uses MasimoSET or Nellcor pulse oximetry to target a user-set SpO2
value.
SpO2 readings will be downloaded directly from the multiparameter patient monitor. SpO2
will be measured using a Phillips MX500 multiparameter monitor (Phillips, Germany, CE
0366).TcPO2 will be measured using a SenTec Digital Monitoring System with OxiVent sensor
(SenTec AG, Switzerland, European patent No. 1535055, CE 0120). Both monitors are
routinely used in clinical practice. Transcutaneous data will be recorded
contemporaneously and the site of the transcutaneous probe will be rotated on each infant
every 2 hours. Control of sensor temperature and application duration are designed to
meet all applicable standards and this monitoring device is used routinely in many
neonatal units.