Vol. 17 •Issue 22 • Page 5
Evidence-Based Guidelines Lower Incidence of VAP
Annals of Internal Medicine recently published an excellent article titled “Evidence-Based Clinical Practice Guidelines for the Prevention of Ventilator-Associated Pneumonia.”1 Although Canadian researchers wrote this guideline, the information is quite applicable for use in the United States.
Much of the information for the guidelines was based on the 1994-1995 guidelines recommended by the Centers for Disease Control and Prevention and the American Thoracic Society.2,3
As most RTs are probably aware, approximately 40 percent of critically ill patients have an infectious disease process. You likely know this because upwards of 60 percent of these patients have a respiratory tract infection like ventilator-associated pneumonia (VAP) or hospital acquired pneumonia (HAP).
Ventilator patients have a six- to 20-fold greater incidence of acquiring pneumonia than those who are not vent patients. Patients at the highest risk of acquiring VAP include elderly people or those with impaired immune defenses including COPDers, burn and neurosurgical patients and those with ARDS or aspiration, and patients who are reintubated or receiving paralytic agents or enteral nutrition.
Patients who get HAP end up with an average hospital stay that is seven to nine days longer than expected. Their risk of dying is almost 6 percent higher than patients who have VAP. More patients die of nosocomial pneumonia than any other illness.
Consequently, any efforts to help decrease the incidence of VAP can reduce its morbidity and mortality and lower health care costs while also improving patient safety.
VAP commonly presents with evidence of a new or persistent infiltrate on chest X-ray, along with fever, leukocytosis, a change in the volume or color of sputum and isolation of a pathogen or hystolic evidence of pneumonia. It is defined as pneumonia occurring 48 hours or more after admission, excluding any infection that is incubating at the time of admission.
The Canadian group, which established the guideline for the prevention of VAP, included a respiratory therapist. The researchers evaluated 18 clinically studied interventions that may help reduce the incidence of VAP. The evidence to support their recommendations came from both level 2 and level 3 clinical studies.
Of the 18 interventions evaluated, researchers agreed that six were proven useful and should be recommended. Two of the interventions were helpful and should be considered for use. There were three interventions not recommended because of insufficient studies or because the studies did not demonstrate the risks outweighed their usefulness. Here are the recommended strategies:
• Use endotracheal rather than nasotracheal intubation. Nasotracheal intubation is associated with an increased incidence of sinusitis. In my experience, with short-term use (of less than 72 hours), sinusitis may not become a problem. Anticipated short-term use of nasotracheal intubation usually turns into more prolonged use, however.
• Use a new ventilator circuit for each new patient. This already is pretty common practice in the United States. The panel conceded that no harm is evident when circuits are not changed on a scheduled basis, but more frequent changes result in higher costs.
• The use of heat and moisture exchangers (HMEs) demonstrated a slightly overall lower incidence of VAP than the use of heated humidifiers. Their use is not indicated for some patients, e.g., those with hemoptic secretions, patients with a high minute ventilation, and those requiring high humidification.
• Weekly changes of HMEs are recommended to lower the incidence of VAP.
• Although evidence does not indicate that either open or closed endotracheal suction catheter use lowers the incidence of VAP, their use is recommended. Scheduled daily changes of these catheters have not shown evidence of lowering the incidence of VAP.
• A semi-recumbent position, with the patient’s head elevated to 45 degrees above horizontal, has proven to lower the incidence of VAP.
Surprisingly, two interventions with no recommendations for routine use included chest physiotherapy (CPT) and prone positioning. What’s surprising is that there is still insufficient clinical evidence to support their recommended use. The small amount of existing evidence, however, indicates that VAP may be lowered with either CPT or prone positioning.
A third intervention with no recommendation is whether or not early tracheostomy helps decrease VAP. Thus far, the evidence was considered inconclusive about early tracheostomy.
Consider for Use
Two interventions to consider for use include kinetic beds and subglottic secretion drainage:
Kinetic beds show definite benefit for decreasing the incidence of VAP, but their increased costs often prohibit their use.
Subglottic secretion drainage has also been demonstrated to be very helpful, but the authors did not specify why it is only something to consider for use. Perhaps it is because the increased cost of a special endotracheal tube with an above-cuff suction catheter is a deterrent. Otherwise, it might be that the skill needed or the potential discomfort or trauma associated with suctioning above the cuff is a factor.
The interventions not recommended include pharmacologic use of sucralfate to decrease the risk of stress ulcer bleeding and the use of either intratracheal or topical antibiotics. Studies that examined the combination of both intravenous and topical antibiotic use revealed a decrease in mortality, however.
1. Dodek P, Keenan S, et. al. Evidence-based clinical practice guideline for the prevention of ventilator-associated pneumonia. Ann Intern Med. (2004;141:305-313).
2. Tablan OC, Anderson LJ, et. al. Guideline for the prevention of nosocomial pneumonia (CDC Advisory Committee). Anns. Infect Control. (1994;22:247-92).
3. ATS Consensus Statement: Hospital acquired pneumonia. Am J Respir Crit Care Med. (1996;153:1711-25).
Michael Hahn is a California practitioner.