Carbon Dioxide, Blood Pressure, and Perioperative Stroke: A Retrospective Case-Control Study.

BACKGROUND: The relationship between intraoperative physiology and postoperative stroke is incompletely understood. Preliminary data suggest that either hypo- or hypercapnia coupled with reduced cerebrovascular inflow (e.g., due to hypotension) can lead to ischemia. This study tested the hypothesis that the combination of intraoperative hypotension and either hypo- or hypercarbia is associated with postoperative ischemic stroke. METHODS: We conducted a retrospective, case-control study via the Multicenter Perioperative Outcomes Group. Noncardiac, nonintracranial, and nonmajor vascular surgical cases (18 yr or older) were extracted from five major academic centers between January 2004 and December 2015. Ischemic stroke cases were identified via manual chart review and matched to controls (1:4). Time and reduction below key mean arterial blood pressure thresholds (less than 55 mmHg, less than 60 mmHg, less than 65 mmHg) and outside of specific end-tidal carbon dioxide thresholds (30 mmHg or less, 35 mmHg or less, 45 mmHg or greater) were calculated based on total area under the curve. The association between stroke and total area under the curve values was then tested while adjusting for relevant confounders. RESULTS: In total, 1,244,881 cases were analyzed. Among the cases that screened positive for stroke (n = 1,702), 126 were confirmed and successfully matched with 500 corresponding controls. Total area under the curve was significantly associated with stroke for all thresholds tested, with the strongest combination observed with mean arterial pressure less than 55 mmHg (adjusted odds ratio per 10 mmHg-min, 1.17 [95% CI, 1.10 to 1.23], P < 0.0001) and end-tidal carbon dioxide 45 mmHg or greater (adjusted odds ratio per 10 mmHg-min, 1.11 [95% CI, 1.10 to 1.11], P < 0.0001). There was no interaction effect observed between blood pressure and carbon dioxide. CONCLUSIONS: Intraoperative hypotension and carbon dioxide dysregulation may each independently increase postoperative stroke risk.

Stroke in Surgical Patients.

Stroke is associated with substantial morbidity and mortality. The aim of this review is to provide an evidence-based synthesis of the literature related to perioperative stroke, including its etiology, common risk factors, and potential risk reduction strategies. In addition, the authors will discuss screening methods for the detection of postoperative cerebral ischemia and how multidisciplinary collaborations, including endovascular interventions, should be considered to improve patient outcomes. Lastly, the authors will discuss the clinical and scientific knowledge gaps that need to be addressed to reduce the incidence and improve outcomes after perioperative stroke.

Perioperative Care of Patients at High Risk for Stroke During or After Non-cardiac, Non-neurological Surgery: 2020 Guidelines From the Society for Neuroscience in Anesthesiology and Critical Care.

Perioperative stroke is associated with considerable morbidity and mortality. Stroke recognition and diagnosis are challenging perioperatively, and surgical patients receive therapeutic interventions less frequently compared with stroke patients in the outpatient setting. These updated guidelines from the Society for Neuroscience in Anesthesiology and Critical Care provide evidence-based recommendations regarding perioperative care of patients at high risk for stroke. Recommended areas for future investigation are also proposed.

Timing and Risk Factors Associated With Postoperative Stroke in Vascular Surgery Patients Using Time-Varying Coefficients From a Cox Model.

BACKGROUND: Mechanisms of postoperative stroke are poorly understood, particularly for strokes occurring after uneventful emergence from anesthesia. We sought to create a model to study retrospectively the timing and associations for stroke in a high-risk surgery population. METHODS: Using a large prospective database containing detailed information on the occurrence and timing of stroke, we identified patients undergoing procedures involving the distal vascular (DV) and the cerebral vascular (CV) to assess the association between perioperative factors and stroke. We used separate Cox regressions with time-varying coefficients, one for each cohort, to assess the association between baseline factors and the timing of postoperative stroke within the DV and CV cohorts. Using time-varying coefficients allows hazard ratios to vary over time rather than assuming that the hazard ratio remains constant with time. Propensity score matching was used to compare the timing of stroke between DV and CV groups. RESULTS: Among the 80,185 patients with qualifying procedures, there were 711 strokes (0.9%) in the first 30 days after surgery. Stroke incidence was lower for DV patients (0.5%, 306/57,553; P < .001) than CV (1.8%, 405/21,940) and the majority of strokes in the DV group were delayed, occurring between postoperative (POD) days 2 and 30 (236/306, 77%). Among the 711 patients who had a stroke, the proportion of strokes that occurred on day 0 was 8% (n = 24 of 306 strokes) in the DV group compared to 35% in the CV group (n = 140 of 405 strokes). Factors associated with stroke on POD 1 for both groups were preoperative mechanical ventilation and emergent procedures. Acute renal failure and female sex were highly associated with delayed stroke (POD 2-30). Perioperative blood transfusion was associated with an increased hazard of delayed stroke in the DV group and a hazard ratio that increased with time in the CV group. CONCLUSIONS: After adjusting for confounding, stroke was more common and occurred earlier in the CV group. Factors associated with delayed postoperative stroke include acute renal failure, emergent procedures, female sex, preoperative mechanical ventilation, and perioperative transfusion.

Recognition and Management of Perioperative Stroke in Hospitalized Patients.

We sought to characterize stroke management and outcomes in a postoperative population. By using the electronic medical records, we identified 39 patients suffering perioperative stroke after noncardiac and nonneurosurgical procedures for whom documentation of management and outcomes was available. Thirty-three strokes occurred during admission, whereas 6 occurred after discharge and were recognized upon return to the hospital. Perioperative stroke was associated with delayed recognition, infrequent intervention, and significant rates of morbidity and mortality, suggesting the need for improved screening and more rapid treatment. There may be disparities in care and outcomes between in-hospital and out-of hospital stroke patients, though further study is warranted.

Perioperative care of patients at high risk for stroke during or after non-cardiac, non-neurologic surgery: consensus statement from the Society for Neuroscience in Anesthesiology and Critical Care*.

Perioperative stroke can be a catastrophic outcome for surgical patients and is associated with increased morbidity and mortality. This consensus statement from the Society for Neuroscience in Anesthesiology and Critical Care provides evidence-based recommendations and opinions regarding the preoperative, intraoperative, and postoperative care of patients at high risk for the complication.

Web-based educational activities developed by the Society for Neuroscience in Anesthesiology and Critical Care (SNACC): the experience of process, utilization, and expert evaluation.

BACKGROUND: Web-based delivery of educational material by scientific societies appears to have increased recently. However, the utilization of such efforts by the members of professional societies is unknown. We report the experience with delivery of educational resources on the Web site of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC), and utilization of those resources by members. METHODS: Three web-based educational initiatives were developed over 1 year to be disseminated through the SNACC Web site (http://www.snacc.org) for society members: (1) The SNACC Bibliography; (2) "Chat with the Author"; and (3) Clinical Case Discussions. Content experts and authors of important new research publications were invited to contribute. Member utilization data were abstracted with the help of the webmaster. RESULTS: For the bibliography, there were 1175 page requests during the 6-month period after its launch by 122/664 (19%) distinct SNACC members. The bibliography was utilized by 107/553 (19%) of the active members and 15/91 (16.5%) of the trainee members. The "Chats with the Authors" were viewed by 56 (9%) members and the Clinical Case Discussions by 51 (8%) members. CONCLUSIONS: Educational resources can be developed in a timely manner utilizing member contributions without additional financial implications. However, the member utilization of these resources was lower than expected. These are first estimates of utilization of web-based educational resources by members of a scientific society. Further evaluation of such utilization by members of other societies as well as measures of the effectiveness and impact of such activities is needed.

Incidence, predictors, and outcomes of perioperative stroke in noncarotid major vascular surgery.

BACKGROUND: Perioperative stroke is a potentially catastrophic complication of surgery. Patients undergoing vascular surgery suffer from systemic atherosclerosis and are expected to be at increased risk for this complication. We studied the incidence, predictors, and outcomes of perioperative stroke after noncarotid major vascular surgery using the American College of Surgeons National Quality Improvement Program database. METHODS: Forty-seven thousand seven hundred fifty patients undergoing noncarotid vascular surgery from 2005 to 2009 at nonVeterans Administration hospitals were identified from the American College of Surgeons National Quality Improvement Program database. An analysis of patients undergoing elective lower extremity amputation, lower extremity revascularization, or open aortic procedures was performed to determine the incidence, independent predictors, and 30-day mortality of perioperative stroke. RESULTS: The overall incidence of perioperative stroke within 30 days of surgery (n=37,927) was 0.6%. Multivariate analysis revealed that each 1-year increase in age [odds ratio 1.02, 95% confidence interval (CI) (1.01 to 1.04)], cardiac history [1.42, (1.07 to 1.87)], female sex [1.47, (1.12 to 1.93)], history of cerebrovascular disease [1.72, (1.29 to 2.29)], and acute renal failure or dialysis dependence [2.03, (1.39 to 2.97)] were independent predictors of stroke. Only 15% (95% CI, 11%-20%) of strokes occurred on postoperative day 0 or 1. Perioperative stroke was associated with a 3-fold increase in 30-day all-cause mortality [3.36, (1.77 to 6.36)] and an increased median surgical length of stay from 6 (95% CI, 2 to 28) to 13 (95% CI, 3 to 43) days (P<0.001, WMWodds 2.5, 95% CI, 2.0 to 3.2) in a matched-cohort assessment. CONCLUSION: Perioperative stroke is an important source of morbidity and mortality, as reflected by significant increases in median surgical length of stay and all-cause 30-day mortality. The independent predictors of stroke that we have identified in this population are not readily modifiable and the majority of strokes occurred after postoperative day 1. Additional studies are required to identify potentially modifiable intraoperative or postoperative risk factors of perioperative stroke.

Cerebral perfusion pressure below 60 mm Hg is common in the intraoperative setting.

BACKGROUND: Maintaining adequate cerebral perfusion pressure (CPP) is of clinical concern in patients with neurological injury. Although there are extensive data on CPP in the ICU setting, there has been little quantitative study of CPP in the intraoperative setting. METHODS: We retrospectively analyzed the electronic intraoperative records of neurosurgical and trauma patients with concurrent intracranial and arterial pressure monitoring devices in continuous use for ≥45 minutes to calculate CPP (=mean arterial pressure-intracranial pressure). We assessed the total minutes and frequency of 5-minute epochs, during which the median CPP was <60 mm Hg, and the associated risk factors. RESULTS: A total of 155 trauma and neurosurgical patients were studied. In the neurosurgery cohort (n=88), 74% had at least one 5-minute epoch during which the median CPP was <60 mm Hg and the median total minutes of CPP<60 mm Hg was 39 [interquartile range (67), length of surgery 274 (300) min]. In the trauma cohort (n=67), 82% had at least one 5-minute epoch of <60 mm Hg, and the median total minutes CPP of <60 mm Hg was 35 [(59), length of surgery 159 (160) min]. For the entire cohort (n=155), patients with CPP<60 mm Hg were found to have higher intracranial pressure compared with patients with CPP≥60 mm Hg (P<0.001). Unlike the neurosurgical cohort, trauma patients with CPP<60 mm Hg had a greater frequency of episodes of mean arterial pressure <70 mm Hg (P=0.001). CONCLUSIONS: CPP<60 mm Hg is common in the intraoperative setting of a tertiary medical center in 2 different surgical populations with intracranial pathology. Prospective studies of intraoperative CPP and neurological outcomes are warranted.

Fatal case of intracerebral hemorrhage during gamma knife treatment for metastases.

This case report presents a patient suffering acute fatal intracranial-intratumoral hemorrhage during a gamma knife treatment session. Acute hemorrhage during a radiosurgery session is extremely rare and a plausible cause for this case is discussed along with a literature review of previously reported incidents. The patient was a 71-year-old male presenting with three large intracranial lesions and an underlying primary renal cell carcinoma malignancy. Because of a severe kyphotic deformity resulting from ankylosing spondylitis, the patient was placed in a moderate Trendelenburg position to allow his head to fit into the gamma knife unit during the radiosurgery session. The two left-sided lesions were to be treated with 20 Gy to the 50% isodose line, and the right-sided lesion with 16 Gy to the 40% isodose line. Anesthesia was available throughout the treatment session to aid with pain control. The gamma knife treatment was aborted because the patient suffered a generalized seizure while in the unit. Immediate head CT of the patient revealed large acute hemorrhages into all three intracranial masses. This proved to be a fatal complication. It is likely that this positioning contributed to the hemorrhage. The clinical history of this patient is provided as well as a review of the literature on acute intracranial hemorrhage associated with radiosurgical therapy.