Respiratory Support of Infants With Congenital Diaphragmatic Hernia

Optimisation of respiratory support of infants with congenital diaphragmatic hernia (CDH) is critical. Infants with CDH often have severe lung hypoplasia and abnormal development of their pulmonary vasculature, leading to ventilation perfusion mismatch. It is vital that lung protective ventilation strategies are employed during both initial stabilisation and post-surgical repair to avoid ventilator induced lung damage and oxygen toxicity to prevent further impairment to an already diminished gas-exchanging environment. There is a lack of robust evidence for the routine use of surfactant therapy during initial resuscitation of infants with CDH and thus administration cannot be recommended outside clinical trials. Additionally, inhaled nitric oxide has been shown to have no benefit in reducing the mortality rates of infants with CDH. Other therapeutic agents which beneficially act on pulmonary hypertension are currently being assessed in infants with CDH in randomised multicentre trials. The role of novel ventilatory modalities such as closed loop automated oxygen control, liquid ventilation and heliox therapy may offer promise for infants with CDH, but the benefits need to be determined in appropriately designed clinical trials.

Randomised crossover trial comparing algorithms and averaging times for automatic oxygen control in preterm infants

ObjectiveAutomatic control (SPOC) of the fraction of inspired oxygen (FiO2), based on continuous analysis of pulse oximeter saturation (SpO2), improves the proportion of time preterm infants spend within a specified SpO2-target range (Target%). We evaluated if a revised SPOC algorithm (SPOCnew, including an upper limit for FiO2) compared to both routine manual control (RMC) and the previously tested algorithm (SPOCold, unrestricted maximum FiO2) increases Target%, and evaluated the effect of the pulse oximeter’s averaging time on controlling the SpO2 signal during SPOC periods.DesignUnblinded, randomised controlled crossover study comparing 2 SPOC algorithms and 2 SpO2 averaging times in random order: 12 hours SPOCnew and 12 hours SPOCold (averaging time 2 s or 8 s for 6 hours each) were compared with 6-hour RMC. A generated list of random numbers was used for allocation sequence.SettingUniversity-affiliated tertiary neonatal intensive care unit, GermanyPatientsTwenty-four infants on non-invasive respiratory support with FiO2 >0.21 were analysed (median gestational age at birth, birth weight and age at randomisation were 25.3 weeks, 585 g and 30 days).Main outcome measureTarget%.ResultsMean (SD) [95% CI] Target% was 56% (9) [52, 59] for RMC versus 69% (9) [65, 72] for SPOCold_2s, 70% (7) [67, 73] for SPOCnew_2s, 71% (8) [68, 74] for SPOCold_8s and 72% (8) [69, 75] for SPOCnew_8s.ConclusionsIrrespective of SpO2-averaging time, Target% was higher with both SPOC algorithms compared to RMC. Despite limiting the maximum FiO2, SPOCnew remained significantly better at maintaining SpO2 within target range compared to RMC.Trial registrationNCT03785899

Dependence of SpO2 signal noise on the pulse oximeter averaging time

A model of the pulse oximeter, which consists of a transfer function between arterial and peripheral blood oxygen saturation (SpO2) and the noise typical for SpO2 records, is an important part of a mathematical model of oxygenation in neonates that is designed to test and compare different algorithms of oxygen control. The noise level in the SpO2 signal is affected by the averaging time setting of the pulse oximeter. This study aimed to characterize the noise level in the SpO2 signal at the set pulse oximeter averaging times of 2- 4, 8, and 16 seconds. We evaluated SpO2 records of 17 healthy volunteers who underwent a laboratory experiment in which they evoked different types of artifacts. The noise level in the SpO2 signal was characterized by two parameters, the deviation of SpO2 from the true value and the SpO2 time stability, defined as the interval during which the measured SpO2 value remained unchanged. Statistical properties of the noise level for the three averaging times were represented by normalized histograms of both the parameters and varied according to the type of artifact. With motion artifacts, the SpO2 readings deviated from the true value by more than ±2% SpO2 in 10%, 7%, or 5% of the measurements when the set averaging time was 2-4 s, 8 s, or 16 s. The length of the interval over which the SpO2 value remained unchanged was most frequently 2 seconds for all set averaging times. Implementation of the noise characteristics into the computer model of oxygenation in neonates will allow more faithful simulations of the output SpO2 signal that better match clinical observations.

Simple Gain-Scheduled Control System for Dissolved Oxygen Control in Bioreactors

An adaptive control system for the set-point control and disturbance rejection of biotechnological-process parameters is presented. The gain scheduling of PID (PI) controller parameters is based on only controller input/output signals and does not require additional measurement of process variables for controller-parameter adaptation. Realization of the proposed system does not depend on the instrumentation-level of the bioreactor and is, therefore, attractive for practical application. A simple gain-scheduling algorithm is developed, using tendency models of the controlled process. Dissolved oxygen concentration was controlled using the developed control system. The biotechnological process was simulated in fed-batch operating mode, under extreme operating conditions (the oxygen uptake-rate’s rapidly and widely varying, feeding and aeration rate disturbances). In the simulation experiments, the gain-scheduled controller demonstrated robust behavior and outperformed the compared conventional PI controller with fixed parameters.

Oxidation of Sulfamethoxazole by Rice Husk Biochar-Activated Persulfate

In the present study, biochars from rice husk were synthesized via pyrolysis at 400, 550, 700 and 850 °C for 1 h under a limited O2 atmosphere, characterized with a various techniques of and used as catalysts to activate persulfate and to degrade sulfamethoxazole (SMX). After physicochemical characterization of biochars. SMX degradation tests were performed using different water matrices, persulfate biochar and SMX concentrations and different initial pH solutions. Also, spiked solutions with bicarbonate, chloride, calcium nitrate, humic acid or alcohols were tested. It was found that catalytic reactivity rises with the pyrolysis temperature. Biochar is crucial for the oxidation of SMX and it can be described with a pseudo first–order kinetic model. Real matrices hinder the oxidation process, in waste water the SMX removal is 41% in 90 min, comparable with the inhibition obtained with spiked with bicarbonates solution (52% removal within 90 min) while complete removal can be achieved in ultrapure water matrices. The presence of alcohol slightly inhibits degradation contrary to the addition of sodium azide which causes significant inhibition, this is an evidence that degradation either under electron transfer/singlet oxygen control or dominated by surface-bound radicals.

Comparison of volume guarantee and volume-controlled ventilation both using closed loop inspired oxygen in preterm infants: a randomised crossover study (CLIO-VG study)

ObjectiveThe objective of this study was to compare two different modes of ventilation in maintaining oxygen saturation (SpO2) in target range (90%–95%) in ventilated preterm infants cared for with automatic control of oxygen delivery (A-FiO2).DesignA single-centre randomised crossover study.SettingsA level III neonatal intensive care unit.PatientsPreterm infants receiving mechanical ventilation and oxygen requirement >21%.InterventionsVolume guarantee (VG) vs volume controlled ventilation (VCV) modes with automatic oxygen control (A-FiO2).OutcomesThe primary outcome of this study was the proportion of time spent with oxygen saturations in the target range (90%–95%) .ResultsNineteen preterm infants with a median gestation age 25 weeks (IQR: 24–28) and birth weight 685 g (IQR: 595–980) were enrolled in the study. There was no significant difference in primary outcome of median proportion of time spent in target saturation between the two arms (72% (57–81) in VG vs 75% (58–83) in VCV; p=0.98). There was no significant difference in the secondary outcomes of time spent in SpO2 <80% (0.03% vs 0.14%; p=0.51), time spent in SpO2 >98% (0.50% vs 0.08%; p=0.54), the median FiO2 (31% vs 29%; p=0.51) or manual adjustments carried out between VG and VCV, respectively. The number of episodes of prolonged hypoxaemia and hyperoxaemia were similar in the two groups.ConclusionThere was no significant difference in time spent in target SpO2 range between VG and VCV when A-FiO2 was used as the FiO2 controller in this crossover randomised control study.Trial registration numberNCT03865069.