A case series on the value of tau and neurofilament protein levels to predict and detect delirium in cardiac surgery patients.

Thomas Saller,Daniel Chappell,Daniel A Reuter,Johannes Ehler,Jens Kuhle,Henrik Zetterberg,Tobias Schürholz,Christian Hagl,Felix Klawitter,Vera Von Dossow,Bernhard Zwissler,Axel Petzold

doi:10.5507/bp.2019.043

Abstract

Delirium following cardiac surgery is a relevant complication in the majority of elderly patients but its prediction is challenging. Cardiopulmonary bypass, essential for many interventions in cardiac surgery, is responsible for a severe inflammatory response leading to neuroinflammation and subsequent delirium. Neurofilament light protein (NfL) and tau protein (tau) are specific biomarkers to detect neuroaxonal injury as well as glial fibrillary acidic protein (GFAP), a marker of astrocytic activation. We thought to examine the perioperative course of these markers in a case series of each three cardiac surgery patients under off-pump cardiac arterial bypass without evolving delirium (OPCAB-NDEL), patients with a procedure under cardio-pulmonary bypass (CPB) without delirium (CPB-NDEL) and delirium after a CPB procedure (CPB-DEL). Delirium was diagnosed by the Confusion Assessment Method for the ICU and chart reviews. We observed increased preoperative levels of tau in patients with later delirium, whereas values of NfL and GFAP did not differ. In the postoperative course, all biomarkers increased multi-fold. NfL levels sharply increased in patients with CPB reaching the highest levels in the CPB-DEL group. Tau and NfL might be of benefit to identify patients in cardiac surgery at risk for delirium and to detect patients with the postoperative emergence of delirium.

Highlights

Neurocognitive dysfunction after cardiac surgery is relevant in the majority of elderly patients because it impairs quality of life and often leads to the need for institutionalized care[1]
In cardiac surgery the inflammatory stimulus causing endothelial activation is induced by the artificial surface of the cardiopulmonary bypass (CPB) circuit[5] in contrast to arterial bypass surgery without cardio-pulmonary bypass (CPB) in offpump cardiac arterial bypass (OPCAB) surgery
Patients were extubated after a mean ventilation time of 13.7±3.8 h after intensive care unit (ICU) admission and received dexmedetomidine and propofol if additional sedation was required before the endotracheal tube could be removed

Summary

Introduction

Neurocognitive dysfunction after cardiac surgery is relevant in the majority of elderly patients because it impairs quality of life and often leads to the need for institutionalized care[1]. A local stimulus due to surgery or trauma is believed to induce systemic inflammation followed by neuroinflammatory responses[3] and an activation of microglia which leads to neuronal damage[4]. This cascade is meant to be crucial in the pathogenesis of delirium. A contact activation of the immune system is held responsible for the severe inflammatory response syndrome (SIRS) often observed after cardiac surgery under CPB and might result in the high incidence rates of delirium in these patients[6]. Delirium following cardiac surgery is a relevant complication in the majority of elderly patients but its prediction is challenging. Tau and NfL might be of benefit to identify patients in cardiac surgery at risk for delirium and to detect patients with the postoperative emergence of delirium

Methods

Results

Conclusion