Is Daily Awakening Always Safe in Severely Brain Injured Patients?

Abstract

Sedation is a central component of critical care to prevent sleep deprivation, pain, anxiety, agitation, and delirium. Daily interruption of sedation (DIS) decreases the duration of mechanical ventilation, shortens hospital stay and may, in combination with spontaneous breathing trials, improve outcome in medical intensive care patients [1, 2]. Moreover, the amount of sedatives and opioids administered, which is directly associated with morbidity (nosocomial infections and thromboembolic events), can be reduced by DIS [1, 2]. Therefore, sedative drugs should be titrated to a lower level when sedation is restarted, which is, in our mind, the major factor contributing to decrease ventilation and ICU days. An estimated 30–40% of intensive care units worldwide have implemented daily interruption of sedation as a routine protocol [3–5]. Even if daily interruption of sedation could be a cornerstone for medical intensive care patients, it has not extensively been studied so far in acutely brain injured patients. So, can these results be translated to patients with subarachnoidal hemorrhage (SAH), intracerebral hemorrhage (ICH), or traumatic brain injury (TBI)? In fact, in a recent randomized control trial, the subgroup of acutely head injured patients did not show decreased ventilation or ICU days when sedation was interrupted on a daily basis (n = 21) compared to controls (n = 17) [6]. The major reason for neurointensivists to prescribe sedative drugs is to decrease oxygen consumption and prevent metabolic distress in the severely injured brain. Unfortunately, continuous sedation can mask important changes that can only be elucidated by clinical exam, which remains so far the gold standard. Therefore, several NICUs in the USA have already implemented the strategy of daily or even twice daily awakening for reliable assessment. Immediate detection of early (brain edema, rebleeding) and late (e.g., delayed cerebral ischemia secondary to cerebral vasospasm) complications in the course of SAH, ICH, and TBI may improve outcome. Modern advances in neurocritical care has led to the implementation of multimodal neuromonitoring, which includes monitoring of ICP (intraparenchymal or with EVD), cerebral metabolism (microdialysis), brain tissue oxygen (PbtO2), and cerebral blood flow (CBF). This may help to early detect complications, however, so far, we are still on the way to introduce these data in the daily care of our patients. So, relying on clinical evaluation by stopping sedatives, do we know whether this is safe for NICU patients or may the risk of metabolic derangement overweigh the benefit of an appropriate exam? The study by Skoglund and coworkers in this issue of the Journal is the first effort to prove safety of daily interruption of sedation in NICU patients. A total of 127 awakening trials with interruption of continuous propofol infusion were studied in 12 TBI and 9 SAH patients. In the majority of patients (13/21) the authors observed an increase in ICP (to mean 22 ± 7 mmHg) and CPP (to mean 79 ± 21 mmHg). In 23 awakening trials (8 patients) a decrease in CPP was observed as ICP increased (C25 mmHg). No other adverse events were reported, and R. Helbok (&) N. Badjatia Division of Critical Care Neurology, Department of Neurology, Milstein Hospital 8 Center, Columbia University, 177 Fort Washington Ave, New York, NY 10032, USA e-mail: raimund.helbok@uki.at