Closed-loop control of the partial pressure of arterial oxygen in neonates

Abstract

A closed-loop control system has been developed to regulate automatically the partial pressure of arterial oxygen (PaO2) to a pre-set level in neonates with RDS (Respiratory Distress Syndrome). A microcomputer-based system is described which uses the PaO2 value from an indwelling umbilical artery electrode as the input to a robust control algorithm. The derived control signal is used to modify the position of a motor driven oxygen/air blender, thus regulating the percentage of oxygen delivered in the inspired gas mixture. The parameters of the control algorithm were conservatively chosen, and the safety aspects of the system are discussed. A total of 48 h of closed-loop control were recorded on seven pre-term infants with mild-to-moderate RDS being nursed in headboxes. Ten separate closed-loop control intervals were recorded, and overall the results showed a marked improvement over comparable periods of manual control. The percentage of time for which the recorded PaO2 was within +/- 1 kPa of the chosen target value (10 kPa) was 74.9 +/- 10.2% when averaged over the ten closed-loop control periods. The corresponding figure for the comparable manual control intervals was 45.2 +/- 16.0%.

Closed-Loop Controlled Inspired Oxygen Concentration for Mechanically Ventilated Very Low Birth Weight Infants With Frequent Episodes of Hypoxemia

“…Closed-loop or semiclosed-loop Fio 2 control systems consisting of various combinations of oxygen delivery mode, feedback signal, and type of controller have been used before in preterm infants [15][16][17][18][19] with positive results in feasibility and effectiveness. Beddis et al 15 and Dugdale et al 16 used Pao 2 measured by indwelling umbilical electrodes as feedback signal, and Fio 2 was delivered by a ventilator and hood, respectively.…”

“…Beddis et al 15 and Dugdale et al 16 used Pao 2 measured by indwelling umbilical electrodes as feedback signal, and Fio 2 was delivered by a ventilator and hood, respectively. Bhutani et al 17 used Spo 2 as feedback signal and Fio 2 was delivered by hood to nonventilated infants.…”

Weaning Preterm Infants from Mechanical Ventilation

“…This is in large part accomplished by avoidance of hyperoxemia resulting from automatic weaning of FiO 2 as soon as saturation exceeds the set target range [31][32][33][34] .…”

Automated Control of Oxygen in Neonates

“…The feasibility and effi cacy of automated FiO 2 adjustment in preterm infants have been documented in several studies (Beddis et al 1979 ;Dugdale et al 1988 ;Bhutani et al 1992 ;Morozoff and Evans 1992 ;Sun et al 1997 ;Claure et al 2001 ;Urschitz et al 2004 ;Claure et al 2009 ;Bucher et al 1994 ). In these trials techniques for automatic FiO 2 adjustment were utilized in neonates receiving various forms of respiratory support and with oxygenation monitored by different methods.…”