Timing and nature of in-house postoperative events following uncomplicated elective endovascular aneurysm treatment
Authors: Arias Eric J. , Patel Bhuvic , Cross DeWitte T. , Moran Christopher J. , Dacey Ralph G. , Zipfel Gregory J. , Derdeyn Colin P. 
Published: August 2014

Object
Most patients with asymptomatic intracranial aneurysms treated with endovascular methods are closely observed overnight in an intensive care unit setting for complications, including ischemic and hemorrhagic stroke, cardiac dysfunction, and groin access complications. The purpose of this study was to analyze the timing, nature, and rate of in-house postoperative events.

Methods
Patients who underwent endovascular treatment or retreatment of unruptured cerebral aneurysms from March 2002 to June 2012 were identified from a prospective case log and their medical records were reviewed. The presentation, patient characteristics, aneurysm size and location, and method of endovascular treatment of each cerebral aneurysm were recorded. Patients with adverse intraprocedural events including perforation and thromboembolism were excluded from this analysis. Overnight postprocedural monitoring was performed in a neurological intensive care unit or postanesthesia care unit for all patients, with discharge planned for postoperative Day 1. Postprocedural events occurring during hospitalization were categorized as intracranial hemorrhage, ischemic stroke, groin hematoma resulting in additional treatment or prolonged hospital stay, retroperitoneal hematoma, and cardiac events. The time from the completion of the procedure to event discovery was recorded.

Results
A total of 687 endovascular treatments of unruptured cerebral aneurysms were performed. Nine treatments were excluded from our analysis due to intraprocedural events. Endovascular procedures included coiling alone, stent-assisted coiling, balloon-assisted coiling, balloon-assisted embolization with a liquid embolic agent, and placement of a flow diversion device with or without coiling. Twenty-seven treatments (4.0%) resulted in postprocedural complications: 3 intracranial hemorrhages, 6 ischemic strokes, 4 cardiac events, 5 retroperitoneal hematomas, and 9 groin hematomas. The majority (20 [74.0%]) of these 27 complications were detected within 4 hours from the procedure. These included 1 hemorrhage, 4 ischemic strokes, 4 cardiac events, 2 retroperitoneal hematomas, and 9 groin hematomas. All cardiac events and groin hematomas were detected within 4 hours. Four (14%) of the 27 complications were detected between 4 and 12 hours, 1 (3.7%) between 12 and 24 hours, and 2 (7.4%) more than 24 hours after the procedure. The complications detected more than 4 hours from the conclusion of the procedure included 2 minor intracranial hemorrhages causing headache and resulting in no permanent deficits, 2 mild ischemic strokes, and 3 asymptomatic retroperitoneal hematomas identified by falling hematocrit levels that required no further intervention or treatment.

Conclusions
The large majority of significant postprocedural events after uncomplicated endovascular aneurysm intervention occur within the first 4 hours; these events become less frequent with increasing time. Transfer to a floor bed after 4–12 hours for further observation is reasonable to consider in some patients.