• Eb, Nairon
• Kamal, A.
• Dm, Olson
• Dr, Busch
• Joseph, J.

Abstract

<h4>Importance</h4>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.<h4>Objectives</h4>This study explored ICP accuracy in the presence of blood and other viscous fluid contaminates in the transducer.<h4>Design</h4>Preclinical comparative design study.<h4>Setting</h4>Laboratory setting using two Natus EVDs, two strain gauge transducers, and a sealed pressure chamber.<h4>Participants</h4>No human subjects or animal models were used.<h4>Interventions</h4>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.<h4>Measurements and main results</h4>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).<h4>Conclusions and relevance</h4>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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