Automated oxygen delivery system
Supplemental Oxygen is used for patient who have problem in their pulmonary function due to severe injury where patients cannot breathe by themselves or due to prematurity or lung disease where by the amount of oxygen in the room air is not enough to maintain their metabolic needs. In this case patients are given with or without mechanical assistance a specific concentration of oxygen to maintain their metabolism. The premature neonates with respiratory failure may require supplemental oxygen for a longer period of time. The use of high concentration of oxygen for a prolonged period may pose a risk for the newborn resulting in oxidative damage to the eyes (retinopathy of prematurity), lungs (bronchopulmonary dysplasia) and central nervous system. On the other hand insufficient oxygen supplement to the premature newborn can result in detrimental effect in multiple organs such as patent ductus arteriosus, hypoxic damage to the brain and pulmonary vasculature which can increase their mortality. Supplemental oxygen is used in adults for acute respiratory failure while they are in the Hospital and chronic pulmonary diseases in and outside the Hospital. Even though the risk from too much oxygen is not as significant as in the newborn, it still poses a danger to some adult patients. At the same time an inadequate amount of oxygen may cause serious injury or death (1). On the other hand, for patients who require mechanical ventilatory support, while inadequate Mechanical ventilation may not provide adequate ventilation, too much mechanical ventilation in itself can result in lung injury(2). Some of those patients on ventilators at some stage are weaned of the mechanical ventilation. Some ventilators have computerized weaning and decision support system (DSS)that is helpful for the clinicians to decide on when to take the patient of the mechanical ventilator(3). Therefore a regulated and balanced oxygen delivery as well as mechanical ventilation that is titrated to the patients needs and within the intended range of oxygenation for the individual patient is very important in averting the possible complication of over-oxygenation, under-oxygenation or mechanical ventilation.
How it works
The automated oxygen delivery system is a combination of three important units: a unit that monitors the patient’s Spo2, CO2, respiratory compliance, respiratory resistance or PEEP, a unit that receives input signal from the monitoring unit and adjusts the amount or concentration of oxygen (FIO2) or mechanical ventilation and a unit that delivers controlled flow of fraction of inspired oxygen (FIO2)or mechanical ventilation(1,2).
Types of oxygen delivery systems
There are three kinds of automated oxygen delivery system. Closed loop control of inspired oxygen concentration (FIO2) delivery system, closed loop mechanical ventilation and dual closed loop control of oxygen delivery system.
Closed loop control of inspired oxygen concentration
Automated closed loop control of inspired oxygen concentration(FIO2) delivery system is a system where by the concentration of supplemental oxygen delivered through nasal cannula, mask or ventilator to the patient is based on the oxygen saturation(SpO2) level of the patient without the need for manual adjustment every time there is a need for change(1).
Closed loop mechanical ventilation
Closed loop mechanical ventilation is a system where by patient receives automated mechanical ventilation. The ventilation is controlled by the level of CO2, O2 in the patient, respiratory compliance and airway resistance or or by PEEP level depending on the system(2,4).
Dual closed loop control system
Dual closed loop control system is a combination of the closed loop control of inspired oxygen and closed loop control of mechanical ventilation(2,4).It automatically adjusts FIO2 and mechanical ventilation based on Spo2 and PEEP of the patient(4). It decreases the amount of time and resource spent in monitoring and controlling the conventional oxygen delivery system by the nurse(5).
1. Claure N, Bancalari E. Automated closed loop control of inspired oxygen concentration. Respir Care. 2013 Jan;58(1):151-61. doi: 10.4187/respcare.01955. Review. PubMed PMID: 23271825. retrieved on 7/20/2013 from http://www.ncbi.nlm.nih.gov/pubmed?cmd=historysearch&querykey=1
2. Tehrani F, Rogers M, Lo T, Malinowski T, Afuwape S, Lum M, Grundl B, Terry M. A dual closed-loop control system for mechanical ventilation. J Clin Monit Comput. 2004 Apr;18(2):111-29. PubMed PMID: 15362273. retrieved from http://www.ncbi.nlm.nih.gov/pubmed/15362273
3. Tehrani FT, Roum JH. Flex: a new computerized system for mechanical ventilation. J Clin Monit Comput. 2008 Apr;22(2):121-30. doi: 10.1007/s10877-008-9113-4. Epub 2008 Mar 7. PubMed PMID: 18324476. http://www.ncbi.nlm.nih.gov/pubmed?cmd=historysearch&querykey=8
4. Tehrani FT. A closed-loop system for control of the fraction of inspired oxygen and the positive end-expiratory pressure in mechanical ventilation. Comput Biol Med. 2012 Nov;42(11):1150-6. doi: 10.1016/j.compbiomed.2012.09.007. Epub 2012 Oct 9. PubMed PMID: 23058098. retrieved from http://www.ncbi.nlm.nih.gov/pubmed?cmd=historysearch&querykey=16
5. Johannigman JA, Branson R, Lecroy D, Beck G. Autonomous control of inspired oxygen concentration during mechanical ventilation of the critically injured trauma patient. J Trauma. 2009 Feb;66(2):386-92. doi: 10.1097/TA.0b013e318197a4bb. PubMed PMID: 19204511. retrieved on 7/20/2013 from http://www.ncbi.nlm.nih.gov/pubmed/19204511
Submited by Jemal Ebrahim