In June 2020, the Intensive Care National Audit & Research Centre reported that 60% of UK critical care unit COVID-19 pneumonia patients with respiratory failure needed intubation and Invasive Assisted Ventilation (IMV) within 24 hours of admission. However, this practice was associated with a 50% mortality (ICNARC – intensive Care National Audit & Research Centre COVID-19 Reports). Continuous Positive Pressure Ventilation (CPAP) is also commonly used as a respiratory support in such patients and whilst it has been reported recently from the RECOVERY-RS study to shorten stay in hospital, reduce the need for IMV and improve survival, it too carries an number of adverse events that result from the raised intra-thoracic pressure. The same study showed that high flow nasal oxygen (HFNO) was no better that ordinary oxygen delivery.
These insights indicate there is an urgent need for a precision oxygen delivery device that not only delivers oxygen to respiratory failure patients, but one that can also target well ventilated regions in the lungs to enhance the critical function of gas exchange. In response to this need, Camcon Medical Ltd., began developing a portable pulsed oxygen delivery device – BiMOD – based on its Intelligent Medical Oxygen Delivery (IMOD) prototype.
BiMOD AND GAS EXCHANGE
BiMOD is designed to improve gas exchange in the lungs. Gas exchange is our most crucial activity that keep us all alive. In spontaneously breathing patients, BiMOD enables inhaled gases like oxygen to travel to areas of the lungs that are still working normally by avoiding acutely injured areas, as in COVID-19 pneumonia, or chronically damaged parts of the lungs in diseases like chronic obstructive pulmonary disease (COPD). This is achieved by two processes firstly delivery of the gases as pulses at the start of the breath and to match the flow rate of these pulses of gas with the patients’ inspiratory flow rate. This ensure they are delivered to the well ventilated and perfused regions of the lung.
BiMOD adds pulses of oxygen and nitric oxide together in the air that patient take in with each breath. These pulses are delivered by means of nasal cannulae or face masks. The pulses are timed to arrive in the nose or mouth just after the start of inhalation. By adding nitric oxide at the same time as oxygen, this ensures the lungs’ capacity to vasodilate only those blood vessels that are receiving the oxygen, so boosting gas exchange.
No equivalent device allows for precision dosing of oxygen and nitric oxide at the start of each breath to optimise equalisation of ventilation and perfusion in the remaining well-ventilated regions of badly damaged alveoli and pulmonary blood vessels.
DELIVERY OF OXGEN AND NITRIC OXIDE
The combination of delivering pulses of nitric oxide and oxygen together was first shown to be effective in a study in respiratory failure patients I conducted in collaboration with the University of Vienna. Our 3-month randomised controlled trial looked at severely hypoxic COPD patients requiring long-term oxygen at home, and showed enhanced gas exchange, improved lung blood flow, and an indication that exercise capacity increased (Thorax 2013).
BIMOD uses Camcon’s unique BAT (Binary Actuation Technology) valve which has been designed and built by Prof Wladsylaw Wygnanski. It is a fast, silent and low energy requiring valve that opens and closes in 6 milliseconds – to administer measured pulses of oxygen and nitric oxide. Each pulse of gas is timed to arrive in the nose or mouth just after the start of inhalation. The timing is critical, as the first part of each inhalation is carried to the best ventilated and perfused regions of the lungs.
THE BIMOD PROGRAMME
THE BIMOD device allows the clinician to monitor and automatically adjust to a patient’s individual oxygen and nitric oxide needs. It is designed to administer precise amounts of oxygen instead of high continuously flowing oxygen. This means that oxygen waste is significantly reduced, providing substantial cost savings for hospital and home care, as well as reduced fire risk.
Camcon Medical is currently undertaking physiological studies to optimise the software-controlled release of gases for nasal and oral breathing, together with enabling display of a patients’ inspiratory flow rates. To gain approval as a medical device, critical care unit patients with a wide range of respiratory failure causes will be studied to demonstrate superior efficacy over CPAP and HFNO in collaboration with medical colleagues in the Royal Papworth Hospital.
The BiMOD device offers a new way of delivering oxygen that has the potential to transform therapeutic delivery of medical gases in all forms of respiratory failure both in spontaneously breathing patients and those requiring mechanical assisted ventilation. BiMOD will be tested, put though clinical trials and refined for mass production in time to help patients suffering from the continuing COVID-19 pandemic.
Professor Tim Higenbottam DSc BSc MA MD FRCP FFPM is President of the Faculty of Pharmaceutical Medicine, (UK RCP) London