Semi-Recumbent Position to Prevent Ventilator-Associated Pneumonia: Is It Possible?
By Joseph Ming Wah Li, MD
Van Nieuwenhoven CA, Vandenbroucke-Grauls C, van Tiel FH, et al. Feasibility and effects of the semirecumbent position to prevent ventilator-associated pneumonia: a randomized study. Crit Care Med. 2006 Feb;34(2):396-402.
Ventilator-associated pneumonia (VAP) is a cause of significant morbidity and mortality among mechanically ventilated patients. Studies with radioactive-labeled enteral feeds have demonstrated an increased frequency of endotracheal aspiration of gastric contents in supine patients. The CDC guidelines for prevention of nosocomial pneumonia advise placement of mechanically ventilated patients in a semi-recumbent position as a VAP prevention measure.
Only one previous study, by Drakulovic and colleagues, has assessed this strategy to prevent VAP.1 That study demonstrated a 75% decrease in the incidence of VAP. But van Nieuwenhoven and colleagues raised two important questions about the findings from the previous study: First, the Drakulovic study placed control patients in a horizontal (zero degrees) position, which is not the standard of care in most ICUs. Most patients are placed at 10 degrees, and this position is elevated as patients are weaned. Second, the Drakulovic study measured patients only once daily but did not monitor their body positions in between the daily measurements.
Dr. van Nieuwenhoven and colleagues set out to determine whether it is feasible to keep mechanically ventilated patients in a semi-recumbent position on a continual basis and whether this measure would prevent VAP. This was a prospective multi-centered trial in which mechanically ventilated patients were randomly assigned to the semi-recumbent position with a target backrest elevation of 45 degrees or standard of care (supine position) with a backrest elevation of 10 degrees. They used a transducer with a pendulum, which was placed on the bed frame to measure the backrest elevation every 60 seconds for up to seven days. They calculated a mean degree of elevation for each patient daily. Nurses always respected the patient’s request for positioning, but a dedicated research nurse restored backrest position to the randomized position whenever possible.
Baseline characteristics for both groups were similar. For the supine (control) group, average elevations were 9.8 degrees on day one and 16.1 degrees on day seven. For the semi-recumbent group, average elevations were 28.1 degrees on day one and 22.6 degrees on day seven. There were no significant differences in numbers of patients who developed VAP in either group.
This study suggests that, despite the use of dedicated research nurses to maintain positioning, it may not be possible to keep patients’ backrests elevated to 45 degrees. Keeping patients’ backrests at an elevation of nearly 30 degrees does not appear to prevent VAP more than keeping patients’ backrests at 10 degrees, the present standard of care.
- Drakulovic MB, Torres A, Bauer TT, et al. Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial. Lancet. 1999;354(9193):1851-1858.
Bar Codes in Medicine: An Opportunity for Quality Improvement
By Alex Carbo, MD
Poon EG, Cina JL, Churchill W, et al. Medication dispensing errors and potential adverse drug events before and after implementing bar code technology in the pharmacy. Ann Intern Med. 2006;145:426-434.
Medication errors and adverse drug events (ADEs) have received much attention in the literature; the use of health information technology to mitigate these errors and ADEs has now been proposed in many areas of healthcare. In an effort to decrease medication-dispensing errors, the U.S. Food and Drug Administration (FDA) mandated bar code use for all medications in hospitals, beginning in April 2006. While this technology has been extensively studied in other industries, there is little data describing its effects in the healthcare system.
Poon and colleagues set out to evaluate whether implementation of bar code technology reduced dispensing errors and the ADEs that might be caused by these miscalculations. In a before-and-after evaluation, they studied more than 350,000 dispensed medication doses in an academic medical center between February 2003 and September 2004.
During the bar code conversion process, the hospital pharmacy built a dedicated repackaging center, which was responsible for affixing a bar code to every dose of medication. These medications were then dispensed in three different configurations: two configurations required staff to verify all doses at least once using bar code scanning, and the third configuration—for commonly dispensed medications that could not be accommodated in a standard carousel machine because of their size or need for refrigeration—required scanning only one dose from each batch.
The authors found a 93% to 96% relative reduction in the incidence of target dispensing errors (P<0.001) and an 86% to 97% relative reduction in the incidence of potential ADEs (P<0.001) in the two configurations that required staff to verify all doses by scanning. The greatest reductions were seen in wrong medication errors (56%), wrong strength/dose errors (71%), wrong formulation errors (90%), and expired medication errors (100%).
In the configuration that did not require scanning of every dose, however, there was a 60% relative reduction in the incidence of target dispensing errors (P<0.001), but a 2.4-fold increase in the incidence of target potential ADEs. This included new errors attributable to wrong strength and wrong medication dispensing.
In light of the FDA’s mandate regarding bar codes, it seems that every hospital has the opportunity to improve patient safety and decrease medication error rates with the use of bar code technology. This study suggests that in order to achieve this benefit these systems should be designed to ensure that every medication dose is verified by scanning during the dispensing process.
Evaluation of a Guideline to Guide Resuscitation
By Cindy Lien, MD
Morrison LJ, Visentin LM, Kiss A, et al. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med. 2006 Aug 3;355(5):478-487.
The survival rate of patients with out-of-hospital cardiac arrest is very low. Thus, guidelines have been developed for termination of resuscitation for those patients who have had no response to advanced cardiac life support provided by emergency medical service (EMS) personnel. Similar guidelines have not yet been developed, however, for situations in which patients receive basic life support from emergency workers trained in the use of an automated external cardiac defibrillator. Patients with little potential for survival are routinely transported to emergency departments, at significant cost to the healthcare system.
Morrison and colleagues present results from the Termination of Resuscitation (TOR) study, a prospective evaluation of a clinical prediction rule for the termination of basic life support by emergency medical personnel trained in the use of automated external defibrillators. The clinical prediction rule, previously developed in a retrospective review of case records from a large urban EMS system, recommends termination of resuscitation if there is no return of spontaneous circulation, no shock administered, and no witness of the arrest by EMS personnel.
In the current study, the authors obtained follow-up data for 1,240 adult patients in Ontario, Canada, who had suffered an arrest of presumed cardiac cause and were subsequently transported to the emergency department after resuscitative efforts. Twenty-four EMS systems participated in the study. The study found that only 0.5% of the patients for whom the clinical prediction rule recommended termination survived (four out of 776 patients). Of the 1,240 total study patients, 41 (3%) survived. The clinical prediction rule recommended continuation of resuscitative efforts for 37 of these 41 patients, resulting in a specificity of 90.2%. The positive predictive value for death was calculated to be 99.5% when termination was recommended.
The TOR trial also determined whether the addition of other criteria to the original prediction rule could further refine the specificity and positive predictive value. They found that the addition to the criteria of a response time greater than eight minutes increased the positive predictive value and specificity to 99.7% and 97.6%, respectively. When the variable “not witnessed by bystander” was added to the clinical prediction rule, both the positive predictive value and specificity increased to 100%. In other words, no patients survived if they had had a completely unwitnessed arrest, no return of spontaneous circulation, and no shocks delivered.
This study identifies a subpopulation of patients with presumed cardiac arrest for whom termination of resuscitative efforts in the field appears reasonable. The authors note that a survival rate of 1% or less has been suggested in past literature as reflective of medical futility. The TOR investigators acknowledge that their study took place before the 2005 AHA Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care were released and that their study protocols were consistent with the 2000 resuscitation guidelines. In light of this information, continued validity testing of the clinical prediction rule under the 2005 AHA protocols is needed.
Nonetheless, it is quite impressive that use of their clinical prediction rule would have resulted in transportation of only 37% of patients (464 of 1,240), rather than 100% of patients, as is currently the practice. If the guidelines described in this article are to be implemented, further studies are necessary to address the training of EMS personnel, who would carry responsibility for terminating resuscitation and notifying families of patients’ deaths.
Prevention of Ventilator-Associated Pneumonia
By Diane Sliwka, MD
Koeman M, van der Ven AJ, Hak E, et al. Oral decontamination with chlorhexidine reduces the incidence of ventilator-associated pneumonia. Am J Respir Crit Care Med. 2006 Jun;173(12):1348-1355. Epub 2006 Apr 7.
Ventilator-associated pneumonia (VAP) is an important nosocomial source of morbidity and mortality. The use of prophylactic antimicrobials to decrease VAP raises concern for antimicrobial resistance. This study evaluates the topical antiseptic chlorhexidine (CHX) as an alternative prophylactic intervention for VAP. CHX has previously been shown to decrease VAP in cardiac surgical patients, but has not been studied in higher risk, long-term-ventilated patients. Because CHX works better for gram-positive organisms, the combination of colistin and CHX (COL + CHX) was also studied for improved gram-negative coverage.
This multi-center, randomized, double-blind, placebo-controlled trial enrolled 385 adult patients. Patients who were expected to be intubated for longer than 48 hours were randomized to 3 arms: CHX alone, CHX + COL, and placebo. Exclusion criteria included known preadmission immunocompromised state, pregnancy, and physical limitation to oral application. Pneumonia was defined by clinical decision-making, which was later confirmed by three blinded intensivists’ reviews of the case records and supported by daily clinical pulmonary infection scores.
The primary endpoint of VAP was diagnosed in 52 of 385 patients: 18% placebo, 13% CHX, and 10% CHX + COL. Rate of VAP in the two treatment groups was lower than placebo and reached statistical significance when compared to placebo. The daily hazard ratio for CHX versus placebo was .352 (95% CI .160, .791); for CHX + COL versus placebo, it was .454 (95% CI .224, .925), showing a 65% and 55% reduction in the rate of pneumonia development. Multivariate analysis of variables such as gender, pulmonary admission diagnosis, colonization at time of admission, and antimicrobial use on admission did not affect the data.
The secondary endpoint of endotracheal colonization was evaluated by a twice-weekly endotracheal culture. There was no statistically significant difference in colonization among the three groups in the first (days 1-4) or third (days 9-12) time frames. During the second time frame (days 5-8), there was a statistically significant decrease in colonization for the CHX + COL treatment group when compared to both placebo (16% versus 40% p<.007) and to CHX (16% versus 38%, p<.011); this decrease is thought to be due to gram-negative coverage by COL.
The secondary endpoint of oropharyngeal colonization was evaluated for 87% of all patient days. CHX and CHX + COL were similarly effective for gram-positive bacteria when compared to placebo, with 30% and 27% reduction in rates of colonization, respectively: HR 0.695 for CHX (95% CI, 0.606, 0.796; p < 0.001) and 0.732 (95% CI, 0.640, 0.838; p < 0.001) for CHX + COL. The CHX + COL combination was more effective for gram-negative bacteria: daily HR .534 (95% CI, 0.455, 0.626; p <0.001) alone with a 47% reduction in gram-negative colonization compared to CHX.
No difference was seen in ICU mortality, duration of mechanical ventilation, or duration of ICU stay. One adverse event (tongue swelling) occurred in the CHX + COL group.
Limitations of the study include the following:
- Daily assessments on all patients were not performed;
- The placebo group had more males and more infections on admission than the other two groups, raising the question of randomization error;
- Clinical versus quantitative diagnosis of pneumonia may overestimate VAP in this study;
- It is not known how many patients were not enrolled in the study due to short anticipated ventilator times, but who later had prolonged ventilations; and
- The lack of effect on ventilator time, ICU length of stay, and mortality raises the question of the significance of these findings.
Despite these limitations, the low cost of these treatments, minimal adverse events, low risk of promoting significant antimicrobial resistance, and the finding of decreased VAP and bacterial colonization risk shown in this study support the potential benefit of topical decontamination with CHX and COL in conjunction with other measures of VAP prevention. TH
- De Riso AJ II, Ladowski JS, Dillon TA, et al. Chlorhexidine gluconate 0.12% oral rinse reduces the incidence of total nosocomial respiratory infection and nonprophylactic systemic antibiotic use in patients undergoing heart surgery. Chest. 1996;109:1556-1561.