 weight also means less fuel.
Aluminium can be enhanced with decorative and protective finishes. Extremely tough anodised and powder/ paint coatings can be very long lasting, carrying 20-year guarantees. Many finishes have low environmental impact and can be recycled easily. Finishes are widely used in architecture, transport, packaging, household appliances, jewellery and furniture.
Widely used in advanced composite materials for aerospace and motor racing, lightweight aluminium foam panels and components. They have reflective qualities used in metallic paints, inks and cosmetics. Also used for brake and friction linings.
Aluminium can be repeatedly recycled without loss of value or properties. The recycling process takes only 5% of the energy used to make the primary aluminium. Huge reductions in CO2 can be achieved by recycling, and using lightweight aluminium in transport. In Europe, about 50% of all aluminium used to make drink cans and other aluminium packaging comes from recycled aluminium. Over 60% of all current European aluminium is made from recycled raw material. Recycling aluminium scrap in Europe saves 90 million tonnes of greenhouse gas emissions in a year – equivalent to the annual emissions from 15 million cars!
Aluminium demand is projected to double by 2020.
New techniques are always evolving to make thinner, stronger products using less material and less energy. Greater recycling will reduce energy consumption and CO2 emissions. The deposits of bauxite are sufficient for the next 300 years. Aluminium use in European cars continues to rise.
Aluminium is here to stay!
Background. Mechanically ventilated very low birth weight infants often present with frequent episodes of hypoxemia, and maintaining arterial oxygen saturation by pulse oximetry (Spo2) within a normal range by manual fraction of inspired oxygen (Fio2) adjustments is difficult and time consuming.
Objectives. An algorithm for closed-loop Fio2 control (cFio2) to maintain Spo2 within a target range was compared with continuous manual Fio2(mFio2) adjustments by a nurse in a group of ventilated infants who presented with frequent episodes of hypoxemia.
Results. Fourteen infants (birth weight: 712 ± 142 g; gestational age: 25 ± 1.6 weeks; age: 26 ± 11 days; synchronized intermittent mandatory ventilation rate: 24 ± 10 b/m; peak inspiratory pressure: 17.5 ± 2.0 cmH2O; positive end-expiratory pressure: 4.3 ± 0.5 cmH2O) were studied for 2 hours on each mode in random sequence. Both modes aimed to maintain Spo2 between 88% and 96%.
There were 15 ± 7 and 16 ± 6 hypoxemic episodes/hour (Spo2 <88%, >5 s) during mFio2 and cFio2, respectively; episode duration was 41 ± 23 and 32 ± 15 s, totaling 19 ± 16% and 17 ± 12% of recording time. There were 13 ± 10 and 10 ± 8 hyperoxemic episodes/hour (Spo2>96%, >5 s) during mFio2 and cFio2,respectively; episode duration was 27 ± 15 and 24 ± 19 s, totaling 15 ± 14% and 10 ± 9% of recording time. Mean Spo2 and Fio2 levels were similar during both modes. The nurse made 29 ± 17 adjustments/hour during mFio2. There was a significant increase in the duration of normoxemia (Spo2 between 88%–96%) during cFio2 (75 ± 13 vs 66 ± 14% of recording time).
Conclusion. In this group of infants, cFio2 was at least as effective as a fully dedicated nurse in maintaining Spo2 within the target range, and it may be more effective than a nurse working under routine conditions. We speculate that during long-term use, cFio2 may save nursing time and reduce the risks of morbidity associated with supplemental oxygen and episodes of hypo- and hyperoxemia.
Very low birth weight (VLBW) infants who require extended mechanical ventilatory support often present with episodes of hypoxemia.1–5 These episodes are detected by arterial oxygen saturation monitoring by pulse oximetry (Spo2) and are usually assisted with a transient increase in the fraction of inspired oxygen (Fio2).
These limitations make the use of a system for automatic Fio2 adjustment a desirable alternative. We have recently developed an algorithm that aims to maintain Spo2 within a target range by closed-loop Fio2 control (cFio2). The primary objective of this study was to evaluate the efficacy of the cFio2 algorithm and secondarily, to quantify the nursing time involved in maintaining Spo2 by manual Fio2 adjustments.
We hypothesized that the cFio2algorithm will be more effective than a neonatal nurse stationed at the infant's bedside in maintaining Spo2within a specific range of normoxemia in a group of mechanically ventilated preterm infants who presented with frequent episodes of hypoxemia.
Preterm infants admitted to the University of Miami Jackson Memorial Medical Center's newborn intensive care unit weighing <1500 g at birth, who required supplemental oxygen and presented with frequent episodes of hypoxemia while undergoing mechanical ventilation, were enrolled in the study. Infants were excluded if judged clinically unstable by the clinical team. The study was approved by the University of Miami Subcommittee for the Protection of Human Subjects, and written informed consent was obtained from the parents or legal guardian of each infant.
The cFio2 system was based on a hybrid algorithm of differential feedback and rule-based control. The algorithm continuously acquired the infant's Spo2 information and adjusted the Fio2 delivered by a mechanical ventilator to maintain Spo2 within a specific range set by the user. The cFio2 algorithm was set to calculate and adjust the set Fio2 once per second on a closed-loop basis by means of a direct electronic interface between the cFio2 system and the ventilator's air-oxygen blender control.
The cFio2 algorithm defines Spo2 ranges based on a user defined target range of normoxemia. It assumes the occurrence of hypo- or hypoxemia whenever Spo2 exceeds or falls below the normoxemic range. The differential feedback control functions are used to deal with the within and between patient variability to changes in Fio2 that, in combination with algorithm's rules, modulate the magnitude and timing of Fio2 adjustments during periods of normoxemia or during a hypo- or hyperoxemic episode. The factors used to determine the adjustments are the current Spo2 level, direction and rate of Spo2 change, degree and duration of the hypo- or hyperoxemic episode, current Fio2 setting, and the individual patient's basal Fio2 requirement during normoxemia. The Fio2adjustments during hyper- and normoxemia are of smaller magnitude and pace than those occurring during hypoxemia.
The rules and control functions built in the algorithm are designed to enable the cFio2 algorithm to modify its response to changing conditions, from slow and subtle Spo2 changes during periods of stability to rapidly falling Spo2during an acute episode of hypoxemia.
The algorithm does not perform additional filtering or validation of the Spo2 information. In the event of missing Spo2 information the cFio2 algorithm locks the Fio2 after a short wait period at a back-up level preset by the user or at the current Fio2 level, whichever is higher, until Spo2 information is available again.
In addition to the standard pulse oximeter alarms, the cFio2 algorithm alerts the user when an episode of hyper- or hypoxemia occurs, when it has lasted for >2 minutes despite Fio2 adjustments, and when these adjustments set the Fio2at 0.21 or 1.0, respectively. The user is also alerted when Spo2 signal is lost. These alerts are intended to direct the user to verify proper function of Spo2 measurement, Fio2 delivery, and communication links.
The reference mode to which the cFio2 algorithm was compared consisted of manual adjustments of the Fio2 made continuously by a neonatal research nurse stationed at bedside, fully dedicated to maintain Spo2 within the same target range of normoxemia.
In the occurrence of a hypoxemic episode (Spo2 <88%), Fio2 was increased by 0.1 and by 0.2 if Spo2 dropped below 80%. Successive increments of the same magnitude were performed every 20 seconds if Spo2 did not return to the desired range or at shorter intervals if Spo2 continued to decline. Additional increments in Fio2 were halted when Spo2 improved, and Fio2 was eventually weaned down after Spo2 had returned to the target range. When Spo2 exceeded the upper limit of the target range, Fio2 was reduced by smaller adjustments until Spo2 returned to the target range.
This mode was used to eliminate personnel-dependent variability in the response time and the Fio2adjustments. This idealized mode of Fio2 control is not feasible in the routine clinical setting because it requires a neonatal nurse dedicated exclusively to monitor Spo2 and adjust Fio2.
Infants were studied for 2 continuous hours on each mode of Fio2 control (cFio2 and mFio2) for a total study time of 4 hours. The sequence of Fio2 modes was determined at random (tossed coin). Both modes aimed to maintain Spo2 within 88% to 96%.
The infants were studied in their incubators with their skin temperature servo-controlled at 36.5°C. They were kept in the same body position as they were before the study period. The infant's endotracheal tube was suctioned before the study.