Date of Award

Summer 6-27-2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Ashley Depriest

Second Advisor

Barbara Hopkins

Third Advisor

Anita Nucci

Abstract

Background: Ventilator associated pneumonia (VAP) is a major cause of morbidity, longer intensive care unit (ICU) stay, increased duration of mechanical ventilation, and increased healthcare cost in critically ill patients. Critically ill patients are at increased risk for malnutrition, which is associated with impaired immune function, impaired ventilator drive and weakened respiratory muscles. Malnutrition has been thought to increase the risk of VAP due to bacterial translocation from the gastrointestinal tract to the lungs. Previous research that has evaluated the effect of enteral nutrition on malnutrition associated with VAP has been inconsistent in part because of the subjectivity of the old definition of VAP. In 2013, the Center for Disease Control and Prevention (CDC) developed a new definition for the diagnosis of VAP, which includes three tiers of a ventilator associated event (VAE); ventilator associated condition, infection-related ventilator-associated complication, or possible or probable VAP). The purpose of this study is to retrospectively examine the relationship between enteral formula, tube-feeding placement site, time of tube feeding initiation and the incidence of VAE using this new CDC definition.

Objective: The aim of the study was to retrospectively examine the relationship between enteral formula, tube-feeding placement site, time of tube feeding initiation and the incidence of VAE using this new CDC definition.

Participants/setting: The medical records of 162 adult patients admitted to one of the ICUs (Medical ICU, Surgical ICU, Neurological ICU, Burn ICU) at Grady Memorial Hospital (GMH) in Atlanta, GA in 2013

Main outcome measures: Demographic and baseline medical characteristics including the type of enteral formula used (standard, immune-modulating, hydrolyzed, immune-modulating and hydrolyzed, or mixed), enteral tube feeding placement (gastric or small bowel), and timing of enteral nutrition (never fed, fed48 hours after admission) were collected.

Statistical analysis: Demographic and baseline medical characteristics were described using frequency statistics and compared by VAE status using the Mann-Whitney U and Kruskal-Wallis tests. The relationship between tube placement, enteral formula, timing of feeding and the diagnosis of a VAE was evaluated using the Chi-square test.

Results: In 2013, 81 patients admitted to the ICU at GMH were diagnosed with a VAE. The median age of the study population (n=162) was 50 years (range, 19 to 88 years) and the median BMI was 27.6 kg/m2 (range, 13.2 to 83.2 kg/m2). The majority of the population was African American (53.1%) and male (64.2%). Most patients were fed through a gastric tube (86.4%), were given an immune-modulating enteral formula (32.1%) and were fed after 48 hours of admission (44.4%). After subdividing by ICU location, 12 of 14 patients (86%) in the Medical ICU who were diagnosed with a VAE were either never fed or fed >48 hours after admission vs. 7 of 13 (54%) of patients in the Medical ICU who were not diagnosed with a VAE (p=0.031). No other relationships between the type of feeding initiation, tube placement, and enteral formula were found by VAE status for the population or by ICU location.

Conclusion: Adults admitted to the Medical ICU may have a reduced risk of developing a VAE if fed within 48 hours of admission. The type of enteral formula provided and the route of administration was not associated with the diagnosis of VAE. Future prospective studies should include all critical care patients to further evaluate the effect of nutrition on VAE outcome.

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