The Presence of Blood in a Strain Gauge Pressure Transducer Has a Clinical Effect on the Accuracy of Intracranial Pressure Readings.

Patients admitted with cerebral hemorrhage or cerebral edema often undergo external ventricular drain (EVD) placement to monitor and manage intracranial pressure (ICP). A strain gauge transducer accompanies the EVD to convert a pressure signal to an electrical waveform and assign a numeric value to the ICP. This study explored ICP accuracy in the presence of blood and other viscous fluid contaminates in the transducer. Preclinical comparative design study. Laboratory setting using two Natus EVDs, two strain gauge transducers, and a sealed pressure chamber. No human subjects or animal models were used. A control transducer primed with saline was compared with an investigational transducer primed with blood or with saline/glycerol mixtures in mass:mass ratios of 25%, 50%, 75%, and 100% glycerol. Volume in a sealed chamber was manipulated to reflect changes in ICP to explore the impact of contaminates on pressure measurement. From 90 paired observations, ICP readings were statistically significantly different between the control (saline) and experimental (glycerol or blood) transducers. The time to a stable pressure reading was significantly different for saline vs. 25% glycerol (< 0.0005), 50% glycerol (< 0.005), 75% glycerol (< 0.0001), 100% glycerol (< 0.0005), and blood (< 0.0005). A difference in resting stable pressure was observed for saline vs. blood primed transducers (0.041). There are statistically significant and clinically relevant differences in time to a stable pressure reading when contaminates are introduced into a closed drainage system. Changing a transducer based on the presence of blood contaminate should be considered to improve accuracy but must be weighed against the risk of introducing infection.

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Copyright © 2024 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.

Déclaration de conflit d'intérêts

Dr. Olson is the editor in chief of the Journal of Neuroscience Nursing. Dr. Busch holds patents that do not generate royalties and are assigned to the University of Pennsylvania and Children’s Hospital of Philadelphia (U.S. Patent 10,827,976, 2020, 10,342,488, 2019). Several authors receive support from the National Institutes of Health/the National Institute of Biomedical Imaging and Bioengineering (to Drs. Busch and Olson [R21EB031261]) and the National Institute of Neurological Disorders and Stroke (to Dr. Busch [U01NS09576]; to Drs. Busch and Olson [R01NS122119, UG3/UH3NS123191]). The remaining authors have disclosed that they do not have any potential conflicts of interest.