• David Allin, Marek Czosnyka, and Zofia Czosnyka.
• UK Shunt Evaluation Laboratory and Academic Neurosurgical Unit, Addenbrooke's Hospital, Cambridge, England.
• Neurosurgery. 2008 May 1; 62 (5): 1158-61; discussion 1161.

ObjectiveThe Sophysa Pressio (Sophysa Ltd., Orsay, France) is a new intracranial pressure monitoring system. This study aimed to evaluate its accuracy and compare it with the popular Codman intracranial pressure transducer (Codman/Johnson & Johnson, Raynham, MA) in vitro.MethodsA computerized rig was used to test the Pressio and Codman transducers simultaneously. Properties that were tested included drift over 7 days, the effect of temperature on drift, frequency response, the accuracy of measurement of static and pulsatile pressures, and connectivity of the system.ResultsLong-term (7 d) relative zero drift was less than 0.05 mmHg. The temperature drift was low (0.3 mmHg/207C). Absolute static accuracy was better than 0.5 mmHg over the range of 0 to 100 mmHg. Pulse waveform accuracy, relative to the Codman transducer, was better than 0.2 mmHg over the range of 1 to 20 mmHg. The frequency bandwidth of the Pressio transducer was 22 Hz. The Pressio monitor can transmit data directly to an external computer without the use of a pressure bridge amplifier.ConclusionThe new Pressio transducer proved to be accurate for measuring static and dynamic pressure during in vitro evaluation.

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