The role of the nurse in ventilator-associated pneumonia/Rol de enfermeria en la neumonia asociada a la ventilacion mecanica.
Hospital acquired pneumonia (HAP) is one of the many nosocomial infections, which is also a common problem in intensive care units throughout the world. In the United States, HAP is the second most common nosocomial infection in adults (Kunis & Puntillo, 2003). Critically ill patients, especially intubated patients, are at a higher risk of acquiring ventilator-associated pneumonia (Kunis & Puntillo, 2003). Ventilator-associated pneumonia (VAP) is a hot topic in critical care settings in the recent few years. Many literatures had addressed this topic and studies had been carried out in order to reduce the occurrence of VAP. Reduce VAP is crucial because it increases the risk of death of critically ill patients and also increases patients' length of stay in intensive care units and consequently, health care costs (Craven, 2000). A number of research also addressed the importance of the prevention of VAP and suggested various methods in preventing VAP. In this paper, risk factors of acquiring VAP, the current nursing practice to prevent VAP and personal reflection on prevention on VAP are discussed.
The pathophysiology of VAP
The pathogenesis of VAP involves the colonisation of gram-negative bacteria at the aerodigestive tract and aspiration of secretions from the upper respiratory tracts into the lower airways (Kunis & Puntillo, 2003). In a healthy person, the body's own flora can help to prevent the colonisation of bacteria and virulent pathogens in the oropharynx. The presence of an endotracheal tube allows for the direct entry of bacteria into the lower respiratory tract, preventing the normal hose defenses which include filtration and humidification of air in the upper airway, epiglottic and cough reflexes, and ciliary transport action (Kunis & Puntillo, 2003). Feldman (1999) found that the colonisation of bacteria occurs as early as 12 hours after intubation, beginning from the oropharynx, then in the stomach and finally in the endotracheal tube. Aspiration of colonised intestinal and oropharynx secretions is also a significant source of infective pathogens in the lungs (Bonten & Weinstein, 2000). Pneumonia that develops during the first few days of mechanical ventilation is called an early onset VAP, while VAP occurs after five days or more after intubation is called a late onset (Dent, 2004). Common causative agents for early onset VAP are Streptococccus pneumoniae and Haemophilus influenzae, whereas Pseudomonas aeruginosa, Acinetobacter and MRSA are noted to cause the late onset VAP (Dent, 2004).
Patients who are at risk of VAP
According to the Centers For Disease Control and Prevention (CDC) in the United States, the following risk factors for VAP are identified (CDC, 2004).
* Colonisation of bacteria of the oropharynx or stomach.
* Conditions that favor reflux, including supine position, insertion of a nasogastric tube and neurological impairment.
* Prolonged use of ventilatory support or potential exposure to contamination of ventilatory accessories, such as ventilator tubings.
* A host of factors including old age, severe underlying conditions.
Pruitt and Jacobs (2005) also pointed out other risk factors which include conditions that increase colonisation by pathogens, such as previous antibiotic therapy and impaired defense mechanisms. In addition, poor infection control technique by health care staff (Pruitt & Jacobs, 2005) and poor oral hygiene in critically ill paitents (Schleder, 2004) also contribute to the occurrence of VAP.
The prevention of VAP
VAP in critically ill patients prolongs their hospitalisation and recovery and significantly increases the risk of complications and death, and more importantly it greatly increases health care costs (Pruitt & Jacobs, 2005). Various studies suggested ways to prevent VAP, and most of these ways are similar.
Pruitt and Jacobs (2005) suggested an optimal method, proposing a non-invasive ventilation if appropriate as it avoided intubation and the high risk of aspiration near the artificial airway. Furthermore, the non-invasive ventilation offered many supportive measures which are also found in traditional mechanical ventilation, including various modes of ventilatory support with volume and settings, and it was a good alternative for patients who had acute exacerbation of COPD (Pruitt & Jacobs, 2005).
If intubation is inevitable, the following preventive measures for VAP were suggested by Evans (2005), Kunis and Puntillo (2003), Pruitt and Jacobs (2005), and Schleder (2004). Prevention of VAP focus on decreasing the risk of aspiration and preventing the entry and colonisation of pathogens in the respiratory tract. Meticulous hand hygiene and infection control were crucial factors in reducing the rate of VAP. Hand hygiene compliance by healthcare staff contributes dramatically to reduced risks of infection for patients because the hands are the most common medium for transmitting pathogens (Storr & Clayton-Kent, 2004). Handwashing has been demonstrated to be effective in preventing or controlling outbreaks of infections caused by resistant organisms such as MRSA (Livingston, 2000). Moreover, strict adherence to handwashing, aseptic techniques and infection control protocol are essential nursing interventions to reduce infection.
The use of an oral artificial airway instead of the nasal type is recommended because nasal intubations increases the risk of developing nosocomial sinusitis thus will further increasing the development of VAP (Pruitt & Jacobs, 2006). Optimal inflation of the endotracheal tube cuff should also be emphasised as to avoid aspiration of secretions into the lungs which accumulate above the cuff. However, cuff pressure should be checked regularly to avoid possible damage to the tracheal wall (Kunis & Puntillo, 2003). Preventing self-extubation is also important as unplanned extubation increases the risk of aspiration, and re-intubation increases the chance of VAP (Pruitt & Jacobs, 2005).
Undertaking aspiration precautions by elevating the head of the bed at 30-45 degrees is suggested to reduce the risk of aspirations, which may lead to the occurrence of VAP (Schleder, 2004).
Performing frequent mouth care is a critical measure to inhibit bacterial growth in the oral cavity, which increases the risk of developing VAP (Pruitt & Jacobs, 2006). Maintaining the patient's oral hygiene is important because contaminated oral secretions would flow to the subglottic area, where small amounts of these secretions might be aspirated causing VAP (Pruitt & Jacobs, 2005). Adequate suctioning is recommended as it prevents oral secretions from pooling and maintaining good oral hygiene which reduces oropharyngeal colonisation (Schleder, 2004).
Another way of preventing VAP is to keep the ventilator circuit clean. According to CDC (2004), the ventilator circuits should be changed only when they are visibly soiled or malfunctioning, and hence should not be changed routinely. Additionally, draining and discarding regularly the condensations in the ventilator tubing are vital in preventing VAP. Some positive aspects of closed suction systems are well-known, including the guarantee of aseptic chain in case of inadequate handwashing avoidance of catheter contamination by non-sterile objects and the risk of environmental cross-contamination, whereas the single use of catheter in open suction system decreases the chance of bacterial colonisation (Zeitoun et al., 2003). However, whether the open suction system or close suction system is more favorable in preventing VAP remains to be an unresolved issue. Zeitoun et al. (2003) suggested that other exogenous risk factors are the more important determinants, such as the aseptic technique of the users of the suction system.
Intubated patients often need an enteral feeding tube for feedings, and such a tube increases the risk of aspiration and VAP. Preventive steps of VAP include monitoring patients' tolerance for gastric feedings, verifying the correct position of the enteral tube, elevating patients' head for at least 30 degrees during feedings and after feedings for 1 hour to minimise the risk of reflux and pulmonary aspiration (Pruitt & Jacobs, 2006).
On top of the VAP preventive measures as discussed, education to health care providers is also essential in reducing VAP. A recent study conducted by Babcock (2004) found that VAP rates in a hospital was significantly reduced after the respiratory care practitioners and intensive care nurses worked together for a staff development program, which VAP was discussed, including its risk factors and prevention. Education is fundamental for the challenging behavioral changes. Together with the knowledge base and motivation, awareness of the preventive measures and nursing practiced could be enhanced (McKenzie et. al, 2004).
Implications for nursing practice
Health care costs are a major concern in the health care industry throughout the world. In Hong Kong, despite moving from an accrual deficit of $1,230.9 million in 2005/06 to $198 million surplus in 2006/07, health care cost remains to be a huge problem to the society (Hospital Authority, 2007). Every year the government subsidises only a limited amount of budget ($27,181 million in 2007) to government hospitals. Thus, the budget has never been enough for the public, and the health care costs are continuously increasing year after year (Hospital Authority, 2007). In response to this, various ways have been considered to reduce health care costs. As discussed earlier in this paper, VAP increases patients' care time, length of stay, and morbidity rate. Consequently, all these negative impacts will increase the health care costs in Hong Kong, especially in the intensive care units. Most of the patients in the intensive care units are intubated and on ventilatory support. Since intubated patients are having a high risk of acquiring VAP, preventive measures are the key. Nurses can contribute a lot in the prevention of VAP, and thereby helps to reduce health care costs. Most of the discussed preventive measures of VAP are largely related to our daily nursing care activities, such as maintaining the good oral hygiene of patients, meticulous hand hygiene and good infection control technique are all contributing to the prevention of VAP. Staff development programs and continuous quality improvement projects are useful to guide, update and continuously improve nursing practice. Nurses can also collaborate with doctors in deciding on the best treatment plan for patients. Some of the intensive care units in Hong Kong have already adopted many of the discussed preventive measures. Some of the intensive care units have designed their own protocol for their staff to adhere, such as performing tooth brushing for intubated patients everyday to maintain a good oral hygiene.
Reflections on professional development
After reading various studies on VAP, it is found that the role of nurses in preventing VAP is crucial. In Hong Kong, many critically ill patients admitted to an intensive care unit acquire various types of pneumonia which prolong their length of stay in the unit. Since this group of patients is vulnerable to VAP, the gate-keeper role for nurses becomes even more important. Strict infection control technique is vital for preventing VAP. In intensive care units, procedures are sometimes performed hastily, and the staff including doctors and nurses may execute inadequate infection control techniques. Therefore practicing strict infection control technique when performing daily nursing care is critical in preventing VAP.
The best practice protocols for preventing VAP are easily available in the web. These preventive methods of VAP in various studies are generally similar and useful. In fact, nurses and other health care professionals have performed different studies to verify their usefulness. Other than setting the unit protocols, constantly updating our knowledge and practice to prevent VAP in critical care settings through readings is another strategy. All new knowledge would help us to update the protocols so that other colleagues in our own hospital as well as from other hospitals may receive the updated knowledge to prevent VAP.
Learning about the pathophysiology, the risk factors and the preventive measures of VAP will promote the nurses' awareness of the problem, thus eventually reducing the occurrence of VAP. Constant education is necessary for nurses in order to update and improve nursing practice. Ultimately, patients' recovery rate would significantly improve, and health care costs can be drastically reduced.
Understanding VAP and its risk factors can make nurses more prepared in handling the problem. Preventive measures should be widely applied to daily nursing care. Each critical nurse can play a functional role in reducing and preventing the occurrence of VAP, subsequently improving the patients' recovery rate and consequently reducing health care costs.
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Amy Kit Man Kwong RN, Staff Nurse, Hong Kong Baptist Hospital, Hong Kong Sek Ying Chair RN; MBA, PhD, Associate Professor, The Nethersole School of Nursing, The Chinese University of Hong Kong, Hong Kong
Lorna Kwai Ping Suen RN, RM; MPH, PhD, Associate Professor, The Nethersole School of Nursing, The Chinese University of Hong Kong, Hong Kong