Professor Steve Morgan from the University of Nottingham writes about the benefits of smart invasive devices after it secured over £800,000 in funding for its smart breathing tube last year.
Invasive devices such as urinary catheters and central venous lines are commonly used in healthcare. They serve a useful purpose but are essentially ‘dumb’ devices used to transfer fluids or gases to or from the body. The global catheters market was valued at $45.26 billion in 2020 and is expected to expand at a compound annual growth rate (CAGR) of 6.4% from 2021 to 2028, according to Grand View Research. A high prevalence of chronic disorders leading to hospitalisation has driven the growth of this market. There is considerable interest in incorporating new sensing technology within these catheters to facilitate ‘smart’ catheters that can monitor key physical and physiological parameters, contributing to the Internet of Medical Things.
The large datasets obtained from such devices can be used to train deep or machine learning algorithms to recognise changes in a patient’s condition. For example, Silicon Valley based company Potrero Medical has developed a smart Foley catheter that measures urine output, intra-abdominal pressure and core body temperature. Algorithms are then used to help to predict acute kidney injury earlier.
Different sensing approaches can be used. Commercially available miniature microelectromechanical systems (MEMS) technology, which integrates sensors or actuators, can be embedded within a catheter. Swedish start-up CathPrint AB is developing a process for printing flexible electronics directly onto catheters. Our interest is in the integration of optical fibre sensors into invasive devices. Optical fibre sensors are a highly versatile platform technology that can make a range of physical and biochemical measurements. This sensing capability, coupled with their small diameter, flexibility and immunity to electromagnetic radiation means that they can add greater functionality to existing medical devices.
In collaboration with Nottingham University Hospitals NHS Trust and P3 Medical, we are developing a smart endotracheal tube known as iTraXS (intra-tracheal multiplexed sensing) which utilises optical fibre pressure and perfusion sensors to monitor the cuff-trachea interface. Incorrect cuff inflation pressure causes significant problems for intubated patients. Around 3% of intensive care patients intubated for over 48 hours suffer tracheal stenosis due to high contact pressure impairing mucosal perfusion, and 1900 patients per year require tracheal resection in the UK alone. 50% of surgical patients in the UK complain of sore throat related to high pressure. If cuff pressure is too low, this also causes harm through increased pulmonary micro-aspiration of fluid materials, a major contributing factor in ventilator associated pneumonia (VAP). VAP occurs in 10-20% of ventilated intensive care patients and on average increases length of stay by six days, and mortality by up to 50%. Each episode costs approximately £12,000 in the UK and $25-40,000 in the U.S. While adequate contact pressure is required to reduce microaspiration and to enable positive pressure ventilation of the lungs, high pressures cause ischemic injury. These competing requirements create a narrow target for the optimal contact pressure.
It is essential to develop a sound value proposition to support adoption of the technology. Conventional ‘dumb’ devices are low-cost disposables, for example, an endotracheal tube typically cost £3-5 and purchasers may be reluctant to invest in a smart tube priced at £100-£200. These sums are a tiny fraction of the cost of surgery, or stay in the intensive care unit, but a business case still needs to be developed based on clinical evidence of the reduction in VAP or prevention of tracheal injury.
Nonetheless, the future is highly promising for smart invasive devices. The range of sensing technology; connectivity within the Internet of Medical Things; and the prevalence of artificial intelligence will lead to better treatment and diagnosis, improved patient outcomes and more efficient healthcare.
