Stroke in Surgical Patients: A Narrative Review

Phillip E. Vlisides, M.D.; Laurel E. Moore, M.D.

Disclosures

Anesthesiology. 2021;134(3):480-492. 

In This Article

Future Directions

There is currently no system for preoperatively testing physiologic factors that may contribute to stroke risk. A targeted assessment of cerebrovascular reserve may help to identify high-risk patients and guide perioperative management. For example, patients with preexisting cerebrovascular disease could undergo preoperative functional magnetic resonance imaging testing for determining cerebrovascular reserve. Such testing would be analogous to neurosurgical patients who undergo mapping for cerebrovascular insufficiency.[87] This mapping could reveal regions of impaired cerebral autoregulation, such that these vascular territories may be passively dependent on blood pressure for adequate cerebral perfusion. This line of investigation may thus ultimately help to identify personalized intraoperative blood pressure and end-tidal carbon dioxide goals for optimizing cerebrovascular perfusion. Such preoperative imaging could also help to detect significant stenosis (e.g., atherosclerotic plaque). Patients at high risk for cardioembolic phenomena could be tested perioperatively with transcranial Doppler high-intensity transient signal analysis. Signs of cerebral emboli could guide perioperative anticoagulation strategies. Updated prediction models are also needed. As discussed previously, risk classification systems generated from National Surgical Quality Improvement Program data do not include key risk factors (e.g., atrial fibrillation, valvular heart disease).[4] Although cardiovascular risk prediction models have been compared for perioperative stroke discriminative ability,[11] information was not reported on stroke risk for given scores or thresholds. As such, a risk prediction model is still needed that comprehensively incorporates all relevant risk factors while presenting quantitative data for stroke risk stratification.

Intraoperative risk factors also warrant further study. For example, emerging data suggest that intraoperative blood pressure commonly falls below lower autoregulatory thresholds,[88–90] and both hypo- and hyperventilation may further reduce cerebral blood flow below thresholds required for hypoxic-ischemic injury.[41] As such, the combination of hypotension and end-tidal carbon dioxide perturbations could be studied in relation to stroke risk using multicenter databases with intraoperative physiologic data points.[91] Near-infrared spectroscopy- and bioimpedance-based strategies can be also tested intraoperatively for defining critical thresholds for cerebral blood flow.[89,92] Postoperative screening and monitoring strategies also require further development. Current clinical assessment tools and serum biomarkers do not appear to have high specificity in the perioperative setting.[71] Neurophysiologic methods (e.g., electroencephalography, transcranial Doppler, bioimpedance) could be tested for detecting cerebrovascular vulnerability postoperatively. Last, a perioperative stroke registry could be created to curate granular detail on preoperative risk factors, surgical subtypes, intraoperative physiology and events, postoperative management, reported etiologies, and long-term trajectory. Detailed clinical information, particularly involving clinical and physiologic events before stroke, along with neuroradiologic imaging (where available), could inform pathophysiologic understanding. These candidate strategies are outlined in Table 5

Conclusions

Perioperative stroke is a detrimental outcome for surgical patients. Furthermore, stroke recognition is often delayed in the perioperative setting, and consequences include death, severe disability, and discharge to long-term care facilities. Risk reduction strategies include delaying elective surgery after recent stroke and medication optimization. Further investigation is required to determine the role of intraoperative physiologic management and stroke risk, and novel strategies are required to improve stroke detection postoperatively. Anesthesiologists can play a vital role in leading the required scientific and clinical efforts to advance perioperative stroke understanding and improve clinical management.

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