Light-triggered precision drug dosing from PVC endotracheal tube biomaterials

There is currently a high death rate due to pneumonia of patients in Intensive Care Units (ICU). A major challenge facing the medical staff in ICU is to keep the patient free from infection. The patient is often taking medicines to weaken their immune systems to allow, for example, a transplant to be accepted by the body instead of rejecting it. Unfortunately this means that their bodies are particularly susceptible to infection. A further complication is that the patient often has several medical devices connecting their body to specialised equipment. One of these is an endotracheal (ET) tube, which is inserted into the patient's trachea channelling air from an artificial ventilator into the lungs. ET tubes are mostly manufactured from PVC, and bacteria are able to attach relatively easily to the surface of the tube, where they rapidly grow and develop into large colonies known as biofilms. This is similar to the bacterial plaque which forms on the teeth. The biofilm is extremely difficult to kill due its resistance to antibiotics and its location on the inside wall of the ET tube. When ventilated air is pumped into the patient's ET tube some of the bacteria growing in the biofilm are shed from the surface and carried down into the lungs and pneumonia develops. We have obtained ET tubes from patients who have either died or recovered in ICU and investigated how much and what types of bacteria are attached to the tubes. These studies have allowed us to develop our research plan to prevent bacteria infecting the ET tube by modifying its surface and so reduce the number of patients dying in ICU.We will still use specific and selective antibiotics against these bacteria, but instead of giving them by injection or as tablets we will chemically bind them to the surface of the ET tube. Some researchers have added antibiotics into the ET tube polymer, but this does not provide sufficient antimicrobial activity at the surface and the tube itself can become mechanically weaker because of the added substances. This weakening can cause collapse of the ET tube and blockage of the patient's airway. In our new approach, we will firstly bind the antibiotics to the surface where the bacteria are going to attach. Then, when we need to, we can break the bonds binding the antibiotic to the plastic surface by shining light from a fibre optic on them. In practice, the doctor will insert a fibre optic through an opening in the patient's ET tube and light will be directed to the inner walls where the bacteria attach. Some of these 'light-dependent' bonds will break releasing antibiotic in a very high concentration right at the attaching bacteria. We have carried out this type of research work before with attaching antibiotics to polymers and have also worked with both light-activated surfaces and molecules. Given this, we have confidence that we will be able to help patients in ICU to recover well by reducing the chance of pneumonia developing and also help the medical device industry in this country by developing a new type of ET tube for manufacture and commercialisation.