Early Detection of Surgical Wound Infections Using Sensor Technology

BACKGROUND:

Surgical site infections (SSI) are notable common complications of cardiothoracic surgery and frequently results in readmission and diminished quality of life. SSI may range from a simple spontaneous limited wound discharge to the more severe deep-seated sternal infections. These combined account for about 16% of all hospital acquired infections with an estimated doubling effect on postoperative length of hospital stay and cost of care. The high costs associated with SSI arise primarily because of prolonged hospital stays and the need for repeated surgical procedures in these patients. Patients with chronic obstructive pulmonary disease (COPD), smoking, diabetes, malnutrition, obesity and need for bilateral harvest of the internal thoracic artery during surgery have been identified as having significantly higher risk of infections. Socio-economic factors are also known contributors to SSI.

Many specialist cardiothoracic centres in the UK have internal governance structures within the hospital to monitor the outcomes of its procedures each year to ensure that the work done is of the highest quality and keeps patients safe. However one area of greatest concern is the apparent lack of robust measures for out-of-hospital wound management for patients that have undergone surgical procedures. With shorter hospitalisations due to improved surgical techniques, patients are often discharged from hospital before their wounds are fully healed. Recent studies suggest that inadequate post-discharge communication and untimely, infrequent follow-up contribute to poorer outcomes (e.g. readmission).

The absence of robust systems for SSI surveillance and monitoring of wound healing after hospital discharge presents a big challenge and often results in serious consequences. Some patients are more vulnerable to surgical site infections particularly after hospital discharge. Consequently wound infections become deep-seated and problematic to treat within the primary care setting. Several reasons are known to contribute to susceptibility to surgical wound infections with the international literature reporting that deprivation is a significant risk factor. Evidence also shows that some patients are unable to self-diagnose their wound infections because of lack of sufficient knowledge at the point of hospital discharge. It is also known that some patients find it hard to access GP services due to lack of the availability for urgent appointments. Having to wait to see a GP is often a barrier to seeking help. Others may be unable to contact their GP practices due to increasing demand.

Evidence from our hospital indicates that from September 2014 to August 2016, there was a combined in-hospital surgical site infection rates for sternal and graft harvest sites of 6.3% (172 out of 2711) for patients that had undergone coronary artery bypass graft surgery alone. In addition, about 1% (27 out of 2711) of these patients had severe deep-seated surgical site infections after hospital discharge that required hospital readmission and additional extensive utilisation of NHS resources for their care. Even if the numbers are understated, surgical site infection represents significant costs to the NHS, ranging from £2,100 to £10,500 per infection depending on the nature of the surgery. Expert opinion suggests that costs can be as high as £20,000 per surgical site infection for complex surgery and up to £14,000 for the more general surgery.

This feasibility project will address this concern through the development and optimisation of an early warning sensor-based technology for remote monitoring of out-of-hospital surgical site wound infections. In addition, the project will explore issues associated with the remote application of the sensor technology itself and develop measures to address them.

RATIONALE, AIMS AND OBJECTIVES OF THE RESEARCH A significant number of patients are re-admitted into hospital after cardiac surgery under the emergency care pathway because of severe surgical site infections. These complications occur because patients are not adequately monitored once they are discharged from hospital and often they do not alert their GP until the infection site becomes deep seated (inside tissues and bones). This is due to their inability to tell the difference between inflammation and early signs of superficial infections that could easily be treated by their GP. Treatment of deep-seated infection requires hospitalisation and costs the NHS in excess of £700 million annually.