Morphological changes in ICP pulse waveform as potential markers for early determination of external ventricular drain clamping trial outcome

Abstract

Introduction External ventricular drains (EVD) are used to manage intracranial pressure (ICP) in aneurysmal subarachnoid hemorrhage (aSAH) patients. After days of use a decision is made to remove the drain or place a shunt, involving EVD clamping and CT imaging to observe ventricular size and clinical status. This practice leads to prolonged hospital stay and radiation exposure. This study applies a validated morphological clustering analysis of KCP pulse (MOCAIP) algorithm to differentiate an intact CSF system from an abnormal one during EVD clamping. We hypothesize that pulses with similar mean ICP should have similar shapes in an intact CSF system. Methods This is a retrospective study with 43 aSAH patients with reported clamping trial, admitted to our institution between 03/2013 and 08/2014. By reviewing clinical notes and pre/post brain imaging results, 25 patients were determined with an intact cSf system (A) and 18 with an impaired one (B). MOCAIP algorithm was applied to ICP signals to form series of artifact-free dominant pulses. Finally, pulses with similar mean ICP were identified and Euclidean and geodesic inter-pulse distances calculated in a 4-hour moving window. Results ANOVA analyses showed significant difference on the standard deviations of Euclidean (p< 0.001) and geodesic distance (p=0.001), between groups A and B. Mann-Whitney U tests were used on the mean distances, showing significant difference on the Euclidean (p=0.007) and geodesic distance (p=0.02) between the two groups. The area under the ROC curve was 0.79 and 0.78 for the standard deviations and 0.74 and 0.71 for the mean Euclidean and geodesic distance respectively. Conclusions Patients with an impaired CSF system showed a larger mean and variability of inter-pulse distances, indicating frequent changes on the morphology of pulses.. This technique may provide a method to rapidly determine if patients will need placement of a shunt or can simply have the EVD removed.