Infection Control Program in Tracheostomized Patients

Healthcare-associated infections (HAIs) are infections that patients acquire during the course of receiving treatment for other conditions within a healthcare setting and are not present or incubating at the time of admission. Medical instrumentation increases the risk of development of HAIs and most patients admitted for health care are exposed to some kind of medical device in the course of their treatment. Such devices include, but are not limited to, venous and urinary catheters, and ventilators.

Most ventilator-dependent patients first undergo respiratory stabilization with a translaryngeal endotracheal tube in a critical care setting. At some time during the course of their disease, translaryngeal tubes are converted to a tracheostomy to provide long-term airway access for ventilatory support.

Tracheostomy is a commonly performed airway surgery for critically ill patients. It is a lifesaving procedure done for mechanical ventilation, bronchopulmonary toileting and reduce pulmonary effort.

Tracheostomy tubes have a main shaft (cannula) attached to a neck plate (or flange), and cuffed tubes have a pilot balloon, which shows whether the cuff is inflated. The neck plate has a slot where ties can be placed, and fenestrated tubes can have a cuff and/or inner cannula. Their insertion is aided with an obturator.

It has variable complications, a common one being secondary infection with bacteria and fungi, which in turn leads- to granulation formation in stoma and on peristomal region. As tracheostomy tube is an indwelling prosthesis, it provides potential surface for growth of bacteria.

In tracheostomized patients, the role of the nose, nasopharynx and upper respiratory mucosa as a defensive mechanism is absent which allows bacteria to have direct access from the stoma to the respiratory tract. Infections in tracheostomy stoma, tracheobronchitis, and pneumonia are common infections that occur after tracheostomy. The risk factor for infection in patients with tracheostomy occurs due to exposure to large amounts of bacteria because they do not pass through the upper airway defense system.

There is a 20 fold increase in the development of respiratory tract infection following mechanical ventilation in tracheostomized or mechanically ventilated patients, the incidence vary between 4% and 28%. The commonest microorganism colonizing the tracheostomy tube leading to respiratory infections include Pseudomonas aeurginosa, Acinetobacter baumanii, and methicillin resistant Staphylococcus aureus, some of these organisms are antibiotic resistant which in turn increase the morbidity and costs involved.

The tracheal cannula is often be exposed to enzymes, antioxidants and bacteria found in the tracheal mucosa, thereby accelerating aggregation, increasing colonization of microorganisms and forming biofilms on the surface of the cannula. The irritation by tracheostomy tube causes local inflammatory reaction and edema leading to bacterial colonization. To avoid the lower respiratory tract infection, careful hygiene of tracheostomy is recommended. Using sterile disposable suction catheters, gentle tracheal suction, bacteria free humidifiers, less visitors are recommended. However, despite of high level of hygiene, exogenous colonization with or without subsequent infection is common.

The outer cannula of tracheostomy tubes are routinely changed for a number of reasons. Regular tube changes are thought to aid in the prevention of stoma granulation tissue formation and tube blockage but are mainly done to reduce the rates of possible infection. Biofilm formation is a commonly cited reason for regular tracheostomy tube changes despite little supporting evidence, as they have are believed to cause deterioration in the tube surfaces. Inner cannulas of tracheostomy tubes act as liners and are changed on a daily or more often basis to prevent mucous build-up. A clinical consensus statement on tracheostomy care emphasized that effective wound care for tracheostomy patients has the positive effects of reducing the infection rate, shortening the time with a tracheal tube and improving patients' life quality. Gauze or moist dressings are widely used to take care of tracheostomy wounds.

Biofilm formation is a unique self-protective mechanism of bacteria, as it protects them from host immune response and antimicrobial agents. Biofilms are complex three dimensional structures, which are composed of bacteria, living in an extracellular matrix made of polysaccharides, nucleic acids and proteins. Studies showed that more than 60% of hospital acquired infections are caused by biofilm forming bacteria on medical devices. These infections are most commonly attributed to Staphylococcus aureus, Pseudomonas, and mixed flora.

Data regarding the colonization rates of tracheostomy tubes and the antimicrobial resistance and biofilm forming potential of bacteria colonizing tracheostomy tubes in Upper Egypt is still lacking.