The intensive care unit of the Department of Neurosurgery was opened in 1984 with the inauguration of the new neurosurgery building and has served for over 30 years as a primary care facility for neurosurgical cerebral and spinal cases, as well as for the postoperative monitoring of patients following neurosurgical procedures. The ICU is operated in close cooperation with the University Clinic for Anesthesiology, General Intensive Care Medicine and Pain Therapy and has been recognized since July 1, 2010, by the Austrian Medical Chamber in accordance with § 11 para. 1 of the Physicians Act 1998 as a training center for the subspecialty of neurosurgical intensive care medicine.
Due to the specialized designation of the unit and many years of experience in the interdisciplinary treatment of neurosurgical conditions, the ICU is an essential training site for nursing staff and physicians from various specialties. In accordance with its specific role, virtually all procedures for the treatment of cerebral and extracerebral organ dysfunctions are available.
Within the framework of the current development plan of the Medical University of Vienna, intensive care medicine—and within it, invasive neuromonitoring—has been defined as a key development focus.
The implementation of comprehensive multimodal neuromonitoring, including conventional intracranial pressure measurement, cerebral partial pressure of oxygen monitoring, and cerebral microdialysis, has been completed, making these monitoring methods fully available.
For the early detection of cerebral secondary ischemia, neurosurgical intensive care relies on highly advanced monitoring techniques. In patients with severe brain hemorrhage, continuous intracranial pressure monitoring, monitoring of cerebral partial pressure of oxygen and metabolism, as well as continuous EEG are part of the standard at our neurosurgical intensive care unit.
This multimodal neuromonitoring not only enables early detection and thus treatment of secondary ischemia, but also allows for a tailored adaptation of individually applied therapies.
Despite major advances in intensive care medicine, the neurological outcome of many patients with subarachnoid hemorrhage remains poor. Neuroinflammation induced by the hemorrhage, impairments of the coagulation cascade, and severe cerebral vasoconstriction often lead to serious ischemic deficits only days after the bleeding event. We were recently able to show that reduced cerebral perfusion caused by this process was associated with an endogenous increase in arterial blood pressure in patients with subarachnoid hemorrhage (Hosmann et al., 2020: Endogenous arterial blood pressure increase after aneurysmal subarachnoid hemorrhage).
In addition to pharmacological elevation of arterial blood pressure, treatment of cerebral vasospasm includes the option of pharmacological vasodilation using endovascular procedures. However, the effectiveness of these neurointerventional techniques is highly controversial, which is why we examined their effects on vessel diameter and the occurrence of cerebral infarctions in a retrospective analysis (Hosmann et al., 2018: Concentrations of Cefuroxime in Brain Tissue of Neurointensive Care Patients).
We observed that the effect of endovascular therapies was only very limited in preventing the occurrence of cerebral infarctions. For this reason, a prospective study was initiated to investigate the influence of intra-arterial papaverine hydrochloride on cerebral metabolism and oxygenation using multimodal neuromonitoring. We found only a short-term improvement in cerebral metabolism in a small number of patients, limited to a few hours after the intervention (Hosmann et al., 2020: The Impact of Intra-Arterial Papaverine-Hydrochloride on Cerebral Metabolism and Oxygenation for Treatment of Delayed-Onset Post-Subarachnoid Hemorrhage Vasospasm). These results led to the use of nimodipine for intra-arterial spasmolysis at our department.
As part of routine monitoring, cerebral microdialysis also allows the determination of the unbound concentration of medications beyond the blood–brain barrier. Especially for antibiotics, the concentration at the site of action is of great importance for their effectiveness. Cefuroxime is considered a cerebrospinal fluid-penetrating antibiotic and is routinely used at our department for perioperative prophylaxis. However, based on pharmacokinetic measurements using cerebral microdialysis, we found that only one third of the concentration measured in plasma actually reaches the brain parenchyma (Hosmann et al., 2018: Concentrations of Cefuroxime in Brain Tissue of Neurointensive Care Patients). The determination of cerebral pharmacokinetics of additional antibiotics is currently under investigation.
Non-convulsive seizures occur very frequently in critically ill patients and are a highly underdiagnosed and underestimated phenomenon, especially in comatose patients. Since the duration of non-convulsive seizures is associated with a significantly increased mortality rate, they should be detected and treated early.
For this purpose, monitoring using continuous EEG is necessary, which was first introduced in 2013 at our intensive care unit as part of a project funded by the Austrian Research Promotion Agency with 1.66 million euros. Within this project, a computer-assisted analysis tool for long-term EEGs was developed in cooperation with the Austrian Institute of Technology and evaluated at our clinic (Herta et al., 2015: Prospective assessment and validation of rhythmic and periodic pattern detection in NeuroTrend: A new approach for in the intensive care unit; Herta et al., 2018: Automated Long-Term EEG Review: Fast and Precise Analysis in Critical Care Patients). For this work, we were awarded the Herbert Reisner Award of the Austrian Society for Epileptology twice, in 2016 and 2018.
The scientific work of recent years on the topic of “multimodal neuromonitoring” has led to broad acceptance of these sometimes complex examinations among nursing and medical staff. As a result, we are now able—being one of the few neurosurgical intensive care units worldwide—to cover the full spectrum of cerebral monitoring and to offer critically ill neurological patients individualized multimodal neuromonitoring.