Too Little Too Late: Empiric Vancomycin Therapy is Ineffective in Trauma ICU Patients
Location
Medical Education Building, LSUHSC-NO
Presentation Date
10-10-2019 10:00 AM
End Date
10-10-2019 12:00 PM
Description
Introduction: Critically ill trauma patients have an increased susceptibility to developing secondary infections. Empiric antibiotic therapy is often necessary in this patient population and Vancomycin (Vanc) is frequently used as a first-line agent to cover methicillin-resistant staphylococcus aureus (MRSA). Rapidly achieving therapeutic levels of Vanc is essential when treating critical illness and may be particularly challenging in this patient population. We sought to determine how effectively therapeutic Vanc levels were reached in our Trauma Intensive Care Unit (TICU) patients and what factors influenced failure to reach them.(1, 2, 3, 9) Methods/Results: We conducted an IRB-approved, retrospective chart review of trauma patients in the TICU treated empirically with Vanc between December 2013 and December 2014. We collected demographic and clinical data including dosage and plasma levels of Vanc and calculated trough levels and rates of elimination. Trough levels of 15-20 mcg/dL were considered therapeutic. Results: We identified 122 TICU patients of which 115 had recorded Vanc levels within 48 hours of initial dosing. Vanc levels were subtherapeutic in 82% and supratherapeutic in 3% of subjects, 48 hours after dosing. After 72 hours, only 24% of patients had reached therapeutic levels and ultimately 59% of our cohort failed to reach therapeutic levels. Failure to reach therapeutic levels at 48 hours was associated with young age (<65 years) and there was no association with gender, body mass index (BMI), volume of fluid received, blood product transfusion volume, injury severity, or total daily dose received. Furthermore, we found that rates of drug elimination were widely variable for many subjects all of which suggests that treatment failure is related to drug metabolism. Conclusions/Discussion: Therapeutic Vanc levels are infrequently reached in our critically injured patients. This appears to be particularly challenging in younger patients at least in part due to variable pharmacokinetics within this patient population. More recently, the physiologic phenomenon of Augmented Renal Clearance (ARC) has become an area of increased research. ARC is characterized by increased renal function that results in increased clearance of renally eliminated medications, like Vancomycin. This phenomenon has been found to be present in certain critically ill/trauma patients. The potential mechanisms and patient risk factors for ARC have not yet been confirmed. Some research has reported a higher incidence of ARC in younger patients, attributing this to younger patients having a greater physiological reserve.(10, 11, 12) Our study calls into question the effectiveness of Vancomycin as an empiric or first-line treatment for MRSA in critically ill trauma patients. And encourages us to explore the patient risk factors contributing to the development of ARC.
Recommended Citation
Perez, Victor Sebastian, "Too Little Too Late: Empiric Vancomycin Therapy is Ineffective in Trauma ICU Patients" (2019). Medical Student Research Poster Symposium. 34.
https://digitalscholar.lsuhsc.edu/sommrd/2019/posters/34
Too Little Too Late: Empiric Vancomycin Therapy is Ineffective in Trauma ICU Patients
Medical Education Building, LSUHSC-NO
Introduction: Critically ill trauma patients have an increased susceptibility to developing secondary infections. Empiric antibiotic therapy is often necessary in this patient population and Vancomycin (Vanc) is frequently used as a first-line agent to cover methicillin-resistant staphylococcus aureus (MRSA). Rapidly achieving therapeutic levels of Vanc is essential when treating critical illness and may be particularly challenging in this patient population. We sought to determine how effectively therapeutic Vanc levels were reached in our Trauma Intensive Care Unit (TICU) patients and what factors influenced failure to reach them.(1, 2, 3, 9) Methods/Results: We conducted an IRB-approved, retrospective chart review of trauma patients in the TICU treated empirically with Vanc between December 2013 and December 2014. We collected demographic and clinical data including dosage and plasma levels of Vanc and calculated trough levels and rates of elimination. Trough levels of 15-20 mcg/dL were considered therapeutic. Results: We identified 122 TICU patients of which 115 had recorded Vanc levels within 48 hours of initial dosing. Vanc levels were subtherapeutic in 82% and supratherapeutic in 3% of subjects, 48 hours after dosing. After 72 hours, only 24% of patients had reached therapeutic levels and ultimately 59% of our cohort failed to reach therapeutic levels. Failure to reach therapeutic levels at 48 hours was associated with young age (<65 >years) and there was no association with gender, body mass index (BMI), volume of fluid received, blood product transfusion volume, injury severity, or total daily dose received. Furthermore, we found that rates of drug elimination were widely variable for many subjects all of which suggests that treatment failure is related to drug metabolism. Conclusions/Discussion: Therapeutic Vanc levels are infrequently reached in our critically injured patients. This appears to be particularly challenging in younger patients at least in part due to variable pharmacokinetics within this patient population. More recently, the physiologic phenomenon of Augmented Renal Clearance (ARC) has become an area of increased research. ARC is characterized by increased renal function that results in increased clearance of renally eliminated medications, like Vancomycin. This phenomenon has been found to be present in certain critically ill/trauma patients. The potential mechanisms and patient risk factors for ARC have not yet been confirmed. Some research has reported a higher incidence of ARC in younger patients, attributing this to younger patients having a greater physiological reserve.(10, 11, 12) Our study calls into question the effectiveness of Vancomycin as an empiric or first-line treatment for MRSA in critically ill trauma patients. And encourages us to explore the patient risk factors contributing to the development of ARC.
Comments
Mentor: Dr. Patrick Greiffenstein, MD, FACS (Department of Surgery)