Vol. 12 •Issue 2 • Page 16
Zeroing in on Ways to Reduce Ventilator-associated Pneumonia
In the years following the arrival of mechanical ventilation, the topic of ventilator-associated pneumonia gradually grew to share the position held by the weather. That is to say, almost everybody talked about VAP, but not all that much was done about it.
Fortunately for intubated patients and for bottom-line hospital departmental managers, the sense of resignation and the stoic endurance to the inevitability of VAP have been replaced with evidence-based practices. From a national governmental level down to a local level, reduction in the incidence of VAP has caught the attention of policy makers, health care providers and hospital administrators.
At the national governmental level, two agencies have published documents about VAP. In 2001, the prestigious Agency for Healthcare Research and Quality (AHRQ) issued its final document, Making Health Care Safer: A Critical Analysis of Patient Safety Practices.1 In 2002, the Centers for Disease Control and Prevention published its draft Guideline for Prevention of Healthcare-Associated Pneumonia.2
Exhaustive in length, Making Health Care Safer represents the efforts of dedicated teams of eminent physicians and other health care providers who closely examined 11 areas of patient care to see whether evidence-based medicine supported changes in clinical practice.
One of these 11 areas is prevention of VAP. The editors and project directors devoted an entire chapter to this topic. The authors look at numerous sources for their estimates of morbidity, mortality and costs. Incidence of VAP ranges from 6 percent to 54 percent of intubated patients, depending on risk factors; cumulative incidence of VAP is approximately 1 percent to 3 percent per day of intubation. VAP is associated with a mortality rate of up to 30 percent, with a late-onset VAP mortality rate of nearly 50 percent. The average cost per episode of nosocomial pneumonia ranges from $3,000 to $6,000 and extends the length of stay an additional 13 days.1
Clearly, the need for reduction in VAP incidence is unquestionable. What then can be done based on the evidence available? The chapter authors discuss four areas of clinical practice that “carry the potential to reduce the incidence of VAP” in intubated patients:
• patient positioning
• continuous aspiration of subglottic secretions
• selective digestive tract decontamination
• administration of sucralfate.
Patient positioning likely contributes to VAP due to the potential for aspiration of gastric secretions. The authors cite three trials of semirecumbent patient positioning (defined as elevation of the head of the bed to 45 degrees) and incidence of VAP.1 In one randomized trial, patients assigned to semirecumbent positioning showed statistically significant reductions in VAP, though, no differences in mortality.
The authors also examined the idea of continuous bed oscillation. Studies have shown that the cost of oscillation for each patient bed is approximately $100 per day. Findings for VAP reduction with continuous oscillation may be less persuasive than those for semirecumbent positioning. Still, because the costs and risks of both semi-recumbent position and oscillation are low, continued trials of both interventions to document effectiveness are needed.1
ASPIRATION OF SUBGLOTTIC SECRETIONS
In addition to gastric aspiration, the authors explored oropharyngeal aspiration of contaminated secretions into the tracheal sterile field as one factor for VAP. Continuous aspiration of subglottic secretions (CASS) is an intervention for limiting contamination. It’s accomplished through intubation with an endotracheal tube that permits suctioning above the cuff. The tube, available since 1997, has a dedicated port for above-cuff suctioning.
The authors review three randomized trials of CASS that took place in the 1990s.3-5 Two trials involved medical and surgical patients mechanically ventilated for greater than 72 hours; the third trial involved only post-cardiac patients. One trial showed statistically significant decreases in VAP with CASS compared to standard treatment. Another trial showed a strong trend toward decreases in VAP. In addition, all three trials reported delay of onset of VAP with CASS.
Trials showed reductions in VAP caused by Staphylococcus aureus and Hemophilus influenza, but not reductions caused by Pseudomonas aeruginosa or Enterobacteriaceae. Similar to the trials of patient positioning, the trials showed no differences in mortality outcomes.
A recent study supports the effectiveness of aspiration of subglottic secretions on VAP reductions.6 In the clinical trial of 150 mechanically ventilated patients (75 patients with subglottic secretion drainage and 75 patients as control), researchers examined intermittent aspiration, not continuous. VAP was present in three patients (4 percent) receiving subglottic secretion drainage and in 12 patients (16 percent) in the control group (p = 0.014). Like the other trial findings, no differences in mortality were statistically significant. In their comments on the potential of CASS in VAP reduction, the authors call for larger trials to more fully address the effect of CASS on VAP.
The delay of onset of VAP and the decreased incidence of S. aureus and H. influenza suggest that the true value of CASS may lie in the prevention — or at least the reduction of incidence — of early onset VAP. If so, CASS “could therefore be targeted to those patients requiring mechanical ventilation for intermediate periods of time (those at greatest risk for early VAP).”1
LIMITING GUT PATHOGENS
Selective digestive tract decontamination (SDD) refers to administration of “non-absorbable” antibiotics applied topically to the gastrointestinal tract, designed to keep the oropharynx and stomach as sterile as possible. In theory, minimizing pathogen presence in secretions from these two areas will reduce introduction of them into the tracheal sterile field.
The authors note that, although SDD isn’t particularly well-adopted in clinical care in the United States, meta-analyses of studies of SDD support its use.1 These analyses show substantial reduction in the risk of VAP and even some reduction in mortality, especially in protocols involving topical and systemic prophylaxis, rather than topical prophylaxis alone.
With its minimal financial impact and noninvasive nature, SDD is very promising for both VAP and mortality reductions. Unclear, however, is the long-term effect of SDD on microbial resistance patterns and subsequently on morbidity and mortality. Further research on SDD should be strongly encouraged.1
SUCRALFATE FOR STRESS ULCERS
Stress ulcer prophylaxis is an area of concern in VAP as well because pathogenic organisms increase in number as gastric acidity levels decrease. The authors explored the use of sucralfate as stress ulcer prophylaxis, instead of pH-altering drugs, such as H2-antagonists.
Data from meta-analyses and one large randomized control trial are inconclusive. The lack of definitive answers, coupled with unanswered questions about gastrointestinal bleeding in patients receiving sucralfate, led the authors to assert that the H2-blockers “seem preferable to sucralfate.”1 Contrary to these findings, though, is another article that cites evidence that sucralfate “has been found to prevent bleeding from stress ulcers without lowering gastric pH.”7
In their concluding remarks about these four interventions, the authors reiterate that VAP is “common, costly and morbid.” Two low-risk interventions — patient positioning and CASS — can be implemented with ease in most institutions. Two pharmaceutical interventions — SDD and sucralfate — are for the moment less easily embraced without further studies.
Comprehensive in its scope of actual recommendations, the draft Guideline for Prevention of Healthcare-Associated Pneumonia 2002 supports several of the same preliminary interventions identified by the AHRQ. These preliminary recommendations include head of bed elevation at an angle of 30 degrees to 45 degrees and use of “an endotracheal tube with a dorsal lumen above the .endotracheal cuff” for aspiration of subglottic secretions.
The guideline makes no preliminary recommendations for the use of rotating kinetic beds or for routine SDD, leaving each matter an “unresolved issue.” The guideline does, however, recommend preliminary use of medication for stress-bleeding prophylaxis. It lists sucralfate, H2-blockers and/or antacids for prevention of gastric colonization. (The final guideline hadn’t been released as this article was going to press. As a matter of public policy, the draft guideline discourages modifications in practice based on preliminary recommendations.)
During election periods, the adage often bandied about is, “all politics is local.” The same notion applies to the topic of VAP interventions. Governmental agency support is almost always welcome in matters concerning patient care. However, agency recommendations remain abstractions until clinical practice changes at the bedside.
At Deborah Heart and Lung Center, Browns Mill, N.J., Co-technical Director of Respiratory Care John Hill, RRT, assessed the usefulness of an endotracheal tube designed for suctioning subglottic secretions.8 The outcome of the 90-day study was successful enough in reducing VAP that the center will be using the special endotracheal tube for an entire year to see if there’s a significant drop in infection rates.
Word about strategies for reducing VAP is beginning to spread, Hill said. “There is a big buzz starting to generate.”
One institution on the West Coast that has taken VAP reduction as a priority is Overlake Hospital Medical Center, Bellevue, Wash. Overlake is a full-service community hospital with slightly fewer than 300 beds. At Overlake, a dedicated multidisciplinary team of health care providers in 1998 began a systematic approach to reducing VAP as part of its larger campaign to enhance medical excellence at the center.
The Overlake VAP Team for Rapid Improvement Project (TRIP) cited five areas of interventions that could be amended to improve patient care and reduce VAP:
• Effective infection control: Hand washing and re-gloving before patient care activities are required for all personnel. In 1998, only 17 percent of technical personnel — other than RNs, MDs and RTs — exhibited consistent hand washing behavior. In 1999, 80 percent of technical personnel exhibited consistent hand washing behavior.
Glove changing in between different procedures at bedside was an additional measure easily implemented, but it required buy-in from all personnel. Not all staff members had been accustomed to considering glove contamination as a vector for nosocomial infection. After introduction of the topic of glove contamination as part of the VAP TRIP initiative, glove changing between procedures on the same patient became routine at Overlake, at least in the ICU where the initiative was focused.
• Mobility issues: VAP TRIP added semi-recumbent positioning to the ventilator protocol and supported early physical therapy assessment to support patient well-being.
• Nutritional and gastrointestinal considerations: VAP TRIP encouraged ongoing assessment of gastrointestinal health and dietary consultation early in the ICU stay.
• Airway and ventilator management: Continuous subglottic suctioning and consistency in respiratory care policies, procedures and protocols were coupled with the installation of new ventilators. The VAP TRIP felt that aspiration of pooled subglottic secretions was the No. 1 cause of VAP at Overlake. The RTs redoubled their efforts at keeping subglottic secretions out of the (ideally) sterile tracheal field.
Staff members felt that new ventilators would decrease the sedation levels necessary to limit behavior often described as “fighting the ventilator.” Reduced sedation levels also could positively influence inadvertent aspiration into the trachea.
Overlake RTs, working with other ICU health care providers, became more aggressive in their weaning efforts as well. They focused on early morning weaning parameters, following a clear weaning protocol.
• Medication management: VAP TRIP called for judicious utilization of antibiotics as well as for sedation medications through a new sedation protocol.
The improvement efforts began in late 1998 and were well under way early in 1999 and continued into 2000. When VAP TRIP members gathered to examine the data accrued during the period since the initiative had begun, they were pleased to see that their efforts and careful planning had clearly paid off.
The mean four-quarter VAP rate per 1,000 device days prior to the VAP TRIP initiative was 33.56. By the fourth quarter of 1999, the VAP rate per 1,000 device days had fallen to slightly more than nine.
The number of patients expected to develop VAP compared with the actual number was 16 expected patients at baseline (pre-1999), and only nine actual patients with VAP in the fourth quarter of 1999. The percentage of mechanically ventilated patients who expired decreased from 23 percent to 14 percent.
Bottom-line costs showed healthy improvements as well. On a case-by-case basis, the reduction in cost went from an average of $23,000 to $11,000 per ventilated patient. And, with the VAP TRIP initiative, the annualized cost of care for all ventilated patients dropped from more than $1.5 million to less than $800,000.
“We knew that our VAP rates were higher than they should have been and in fact had been creeping up over the last year or so,” said Terry Smith, RRT, director of respiratory care at Overlake Hospital Medical Center. “We were still surprised at how much of an effect we were able to make with minimal amounts of investment of time and resources by our staff.”
To maintain momentum gained from the VAP TRIP initiative, Smith created a respiratory clinical specialist position. The specialist served as mentor and as quality controller to make certain that all staff members were adhering to the policies and procedures outlined in the initiative.
“The specialist began the VAP TRIP work as a volunteer and then transitioned to a paid position. Having a specialist helped us keep focused on our therapeutic objectives, even when our case loads grew heavy and our therapists were challenged with more patients than usual,” Smith said.
Smith stressed that respiratory departments can’t be expected to be the single source for VAP reductions…”When VAP arises from so many multifactorial areas,” he said, “a multidisciplinary effort is required for optimal success.” When discussing the AHRQ studies showing decreases in VAP through certain strategies but minimal effects on mortality, Smith simply smiled. “This may be one time that clinical practice tells a better story than research does,” he said.
1. Shojania KG, Duncan BW, McDonald KM, et al., editors. Making health care safer: a critical analysis of patient safety practices. Evidence report/technology assessment No. 43. San Francisco: The University of California at San Francisco-Stanford Evidence-based Practice Center; 2001. Contract No. 290-97-0013. Sponsored by the Agency for Healthcare Research and Quality.
2. Centers for Disease Control and Prevention Healthcare Infection Control Practices Advisory Committee. Guideline for prevention of healthcare-associated pneumonia [draft]. 2002. Available from: URL: www.cdc.gov/ncidod/hip/pneumonia/DraftPneu_Guide_2002acc.pdf
3. Mahul P, Auboyer C, Jospe R, Ros A, et al. Prevention of nosocomial pneumonia in intubated patients: respective roles of mechanical subglottic secretions drainage and stress ulcer prophylaxis. Intensive Care Med. 1992;18:20-5.
4. Valles J, Artigas A, Rello J, Bonsoms N, et al. Continuous aspiration of subglottic secretions in preventing ventilator-associated pneumonia. Ann Intern Med. 1995;122:179-86.
5. Kolleff MH, Skubas NJ, Sundt TM. A randomized trial of continuous aspiration of subglottic secretions in cardiac surgery patients. Chest. 1999;.116:1339-46.
6. Smulders K, van de Hoeven H, Weers-Pothoff I, Vandenbroucke-Grauls C. A randomized clinical trial of intermittent subglottic secretion drainage in patients receiving mechanical ventilation. Chest. 2002;121:858-62.
7. Kolleff M. The prevention of ventilator-associated pneumonia. NEJM. 1999;340:627-34.
8. Seize the day: when it comes to VAP, look beyond typical measures. Advance for Respiratory Care Practitioners. 2002;15(20):14.
Dr. Howell is an award-winning freelance medical writer based in the Bay Area of California.
For more information about the Overlake Hospital Medical Center VAP TRIP initiative, contact Terry Smith at email@example.com.