Determinants of outcome in patients with a clinical suspicion of ventilator-associated pneumonia

No Decrease in Early Ventilator-Associated Pneumonia After Early Use of Chlorhexidine

BACKGROUND

Oral chlorhexidine prophylaxis can decrease occurrence of ventilator-associated pneumonia. However, the importance of timing has never been fully explored.

OBJECTIVE

To see if early administration of oral chlorhexidine is associated with lower incidence of early ventilator-associated pneumonia (within 5 days of admission to intensive care unit) in intubated air ambulance patients.

METHODS

A single-center, retrospective cohort study of intubated adults transported by a university-based air ambulance service and admitted to a surgical intensive care unit from July 2011 through April 2013. Primary exposure was time from helicopter retrieval to the first dose of oral chlorhexidine in the intensive care unit. Early chlorhexidine was defined as receipt of the drug within 6 hours of helicopter departure. The primary outcome was clinical diagnosis of early ventilator-associated pneumonia. Patients who were less than 18 years old, died within 72 hours of admission, or had pneumonia at admission were excluded.

RESULTS

Among 134 patients, 49% were treated with chlorhexidine before 6 hours, 84% were treated before 12 hours, and 11% were treated for early pneumonia. Early chlorhexidine (before 6 hours; 15%) was not associated (P = .21) with early pneumonia (8%). Furthermore, median times to chlorhexidine did not differ significantly (P = .23) between patients in whom pneumonia developed (5.2 hours) and patients with no pneumonia (6.1 hours).

CONCLUSIONS

Early administration of oral chlorhexidine in intubated patients was not associated with a reduction in the incidence of ventilator-associated pneumonia in a surgical intensive care unit with high rates of chlorhexidine administration before 12 hours.

Objective surveillance definitions for ventilator-associated pneumonia

OBJECTIVES

The subjectivity and complexity of surveillance definitions for ventilator-associated pneumonia preclude meaningful internal or external benchmarking and therefore hamper quality improvement initiatives for ventilated patients. We explored the feasibility of creating objective surveillance definitions for ventilator-associated pneumonia.

DESIGN

We identified clinical signs suitable for inclusion in objective definitions, proposed candidate definitions incorporating these objective signs, and then applied these definitions to retrospective clinical data to measure their frequencies and associations with adverse outcomes using multivariate regression models for cases and matched controls.

SETTING

Medical and surgical intensive care units in eight U.S. hospitals (four tertiary centers, three community hospitals, and one Veterans Affairs institution).

PATIENTS

Eight thousand seven hundred thirty-five consecutive episodes of mechanical ventilation for adult patients.

INTERVENTIONS

We evaluated 32 different candidate definitions composed of different combinations of the following signs: three thresholds for respiratory deterioration defined by sustained increases in daily minimum positive end-expiratory pressure or FIO2 after either 2 or 3 days of stable or decreasing ventilator settings, abnormal temperature, abnormal white blood cell count, purulent pulmonary secretions defined by neutrophils on Gram stain, and positive cultures for pathogenic organisms.

MEASUREMENTS AND MAIN RESULTS

Ventilator-associated pneumonia incidence, attributable ventilator days, hospital days, and hospital mortality. All candidate definitions were significantly associated with increased ventilator days and hospital days, but only definitions requiring objective evidence of respiratory deterioration were significantly associated with increased hospital mortality. Significant odds ratios for hospital mortality ranged from 1.9 (95% confidence interval 1.2-2.9) to 6.1 (95% confidence interval 2.2-17). Requiring additional clinical signs beyond respiratory deterioration alone decreased event rates, had little impact on attributable lengths of stay, and diminished sensitivity and positive predictive values for hospital mortality.

CONCLUSIONS

Objective surveillance definitions that include quantitative evidence of respiratory deterioration after a period of stability strongly predict increased length of stay and hospital mortality. These definitions merit further evaluation of their utility for hospital quality and safety improvement programs.

Is a ventilator-associated pneumonia rate of zero really possible?

PURPOSE OF REVIEW

The increasing number of hospitals reporting ventilator-associated pneumonia (VAP) rates at or close to zero begs the question of whether zero should become the national benchmark for VAP. This article explores the significance of very low VAP rates, reviews differences in surveillance and clinical rates, proposes reasons for their discrepancies, and suggests possible objective alternatives for surveillance.

RECENT FINDINGS

Surveillance rates of VAP are decreasing, whereas clinical diagnoses and antibiotic prescribing remain prevalent. This growing discrepancy reflects the lack of objective and definitive signs to diagnose VAP. External reporting pressures may be encouraging stricter interpretation of subjective signs and other surveillance initiatives that can artifactually lower rates. It is impossible to disentangle the relative contribution of care improvements versus surveillance effects to currently observed low VAP rates.

SUMMARY

The increasing mismatch between surveillance rates and clinical diagnoses limits the utility of official VAP rates to estimate disease burden and guide quality improvement. Advocates are advised to consider objective alternatives such as average duration of mechanical ventilation, length of stay, mortality, and antibiotic prescribing. Emerging surveillance definitions that use more objective criteria may better reflect and inform future clinical practice.