1. Miller, Wendy R.

Article Content

In this issue of JNN, researchers report on a study in which they examined the optimal period for which an external ventricular device (EVD) should be closed to obtain accurate intracranial pressure (ICP) values. This article is an excellent example of nurse researchers forming an important clinical research question based on observations and then developing and implementing an experiment to answer it. The results of this research are extremely relevant to clinical practice.



The purpose of this study was to determine the optimal period for which an EVD should be closed to obtain accurate ICP values.



Neuroscience nurses caring for patients with acquired brain injury commonly rely on ICP measurements-a vital element of assessment in this patient population-as part of their assessment. Intracranial pressure measurements often guide important treatment decisions for patients. However, there is little evidence to guide the appropriate amount of time that an EVD should be clamped to render accurate ICP readings. There is a need to generate evidence that will inform guidelines for the most accurate ICP measurement using EVDs.



Thirty participants with EVDs in place underwent continuous ICP monitoring (with EVDs clamped) for 15 minutes. A protocol was put in place to ensure that patients' ICPs did not reach unsafe levels. Conditional probabilities were calculated to examine the probability of observing the maximum ICP value within a given time point.



The conditional probability of observing a patient's highest ICP, if ICP is observed for 5 minutes, was 0.0181. The conditional probability increased to 0.0402 if ICP is observed for 10 minutes. None of the patients' ICPs reached unsafe levels during data collection. Thus, continuous ICP monitoring for at least 10 minutes seems to be a safe and required amount of time to generate accurate readings.



Nurses relying on the use of ICP measurements via EVDs as part of their assessments should consider developing and implementing protocols that call for at least 10 continuous minutes of EVD clamping; safety thresholds should be included in such protocols, as was performed in the current study.