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.