Effect of a Silver-Coated Endotracheal Tube on Ventilator-Associated Pneumonia and Medical Resource Utilization in Clinical Practice

Background: Ventilator-associated pneumonia (VAP) is associated with excess medical resource utilization (MRU). A silver-coated endotracheal tube (SC-ETT) reduced the rate of microbiologically-confirmed VAP compared with a conventional ETT in a large randomized trial (relative risk reduction, 36%; 95% confidence interval [CI], 4% – 69%; p = .03; JAMA 2008;300:805-13), which may have implications for clinically diagnosed VAP rates and MRU.

Objective: To evaluate VAP rates diagnosed by clinical criteria and MRU before and after systematic implementation of SC-ETT use in clinical practice.

Methods: In this retrospective study, we determined VAP rates and MRU for the 12-month periods before and after systematically replacing conventional ETTs with SC-ETTs in high-risk patients in April 2008 in a large university hospital. We identified adults requiring ≥2 days of mechanical ventilation (ICD codes 96.71 and 96.72) and performed detailed chart review to determine the combined rate of VAP by either National Healthcare Safety Network (NHSN) criteria or clinically significant VAP as defined by abnormal chest x-ray, CPIS ≥7, and 3 days of appropriate antibiotics. Intervention consisted of intubation with SC-ETTs in high-risk patients, defined as requiring mechanical ventilation in the emergency department or intensive care unit (ICU), or on wards. SC-ETT use was also encouraged in patients likely to require postoperative mechanical ventilation; otherwise, conventional ETTs were used in the operating room.

Results: We reviewed 314 ventilator episodes lasting ≥2 days before systematic SC-ETT use and 274 during it. VAP rates per 1000 days of mechanical ventilation decreased from 32.7 (95% CI, 29.3–36.6) before intervention to 17.9 (95% CI, 15.1–21.2; p = .0002 during it (including some patients not intubated with SC-ETT). The corresponding mean duration of antibiotic use decreased from 8.9 to 6.1 days (p = .003). Between-cohort differences in durations of stay in the ICU and hospital were not statistically significant in 546 patients with unique records (pre-intervention, 290; intervention, 256).  

Table. VAP and MRU before and after systematically replacing conventional endotracheal tubes with silver-coated endotracheal tubes
Variable	Pre-intervention	Intervention	P value
VAPa rate/1000 ventilator days (95% CI)	32.7 (29.3–36.6)	17.9 (15.1–21.2)	.0002
Mean duration, days ± standard deviation
Antibiotic use	8.9 ± 11.5	6.1 ± 8.6	.003
ICU stay	13.3 ±11.9	12.3 ± 12.3	.191
Hospital stay	21.2 ± 16.1	19.9 ± 17.7	.103

^a VAP by NHSN or clinically significant criteria.

Conclusions: Systematic use of SC-ETT was associated with lower VAP rates and shorter duration of antibiotic use in clinical practice. More studies are needed to confirm our findings.

 FUNDING: C. R. Bard provided funding for the epidemiologic and statistical analyses.