Anesthesia during endovascular therapy for stroke

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Davis MJ, et al. "Anesthetic management and outcome in patients during endovascular therapy for acute stroke". Anesthesiology. 2012. 116(2):396-405.
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Clinical Question

Do patients with thromboembolic stroke undergoing endovascular thrombolysis under general anesthesia have modifiable risk factors versus those receiving local anesthesia only that contribute to post-stroke neurologic outcomes?

Bottom Line

After adjustment for stroke severity, general anesthesia and SBP < 140mmHg were predictors of poor neurologic outcome in patients requiring endovascular intervention for acute stroke.

Major Points

Background: Studies concerning anesthetic management during endovascular treatment of acute stroke are scarce. Currently available studies do show general anesthesia to be a predictor for poor outcome compared to local anesthesia/sedation, however it is not clear whether modifiable factors are contributing to the poor outcome.

Study Design/Outcomes: In a retrospective cohort study, the neurological outcome of patients receiving endovascular therapy for acute ischemic stroke were measured and risk factors for poor outcome were recorded. After adjusting for stroke severity, patients receiving general anesthesia were less likely to have a good outcome. Additionally, blood pressure equal to or greater than 140 mmHg was a predictor for good outcome.

Interpretation: Although baseline stroke severity, blood pressure greater than or equal to 140 mmHg and use of local anesthesia/sedation were shown to be independent risk factors for good neurological outcome following endovascular treatment of acute stroke, this study was small in sample size, had a retrsopective design and contained other limitations in methods which make interpretation difficult. Furthermore, stroke severity measures may be inadequate. In other words, certain severity factors that contribute to poor outcome may not be captured with the currently available severity measures. If baseline stroke score could be completely characterized, this score may be the sole predictor of outcome and not anesthetic management or blood pressure goals as this article would suggest.

Guidelines

The relevant guidelines relating to this study, or {{no guidelines}} if no guidelines are available.

Design

Bulleted list incorporating the following:

  • Trial type: Retrospective chart review, single center
  • N=number of patients enrolled: 96
    • Experimental arm (n=number of patients in this arm): 48
    • Standard (n=number of patients in this arm): 48
  • Setting: where the study took place: University of Calgary
  • Enrollment: years in which patients were enrolled: 2003-2009
  • Mean follow-up: Clincal outcome at 3 months was assessed
  • Analysis: Treatment received
  • Primary outcome: Neurologic deficit at 3 months (modified Rankin Score)

Population

Inclusion Criteria

- patients receiving endovascular therapy for acute ischemic stroke from January 2003 to September 2009

- patients with thromboembolic stroke involving middle cerebral artery occlusion, extracranial internal carotid occlusion, intracranial carotid “T” occlusion, and basilar artery occlusions that were offered intra-arterial thrombolysis

Exclusion Criteria

Neurologic outcome was not able to be determined in 33 patients' charts, so they were excluded. There was also one patient for whom the anesthetic management couldn't be determined, bringing the N down from 97 to 96.

Baseline Characteristics

Characteristics that were not evenly distributed between the local anesthesia and general anesthesia groups include:

  • Sex
  • NIHSS
  • Diabetes mellitus
  • Blood glucose
  • Minimum systolic and diastolic pressures
  • Discharge destination

Interventions

Patients with thromboembolic stroke in the locations described in inclusion criteria were offered intra-arterial thrombolysis. This entails break down of occluding clots by pharmacological means. It works by stimulating secondary fibrinolysis by plasmin through infusion of analogs such as tissue plasminogen activator which normally activates plasmin.

The choice of anesthetic technique was made by neurologist, anesthesiologist, and radiologists collectively. Patients managed with local anesthesia were given intermittent doses of midazolam (2.5mg) and fentanyl (25 mcg) every 15-30 minutes. If deep sedation deemed necessary tracheal intubation,, mechanical ventilation, and nueromuscular blockade were implemented. General goals were to maintain blood pressure with 10% of preanesthetic values. to Description of the interventions employed in the trial, with enough supportive information to allow a non-expert MD to understand how patients were treated.

Outcomes

Primary Outcome

Modified Rankin score (0-2) for 3 months post-stroke: 22 patients had no-minimal neurologic deficits (mRS 0-1), 37 patients were functionally independent (mRS 0-2), and 25 patients died.

Secondary Outcomes

Same as above, for secondary outcomes.

Subgroup Analysis

Description of clinically relevant subgroup analyses. Since these are usually post hoc and therefore only hypothesis-generating, link to prospective trials of particular subgroups when possible.

Adverse Events

Description of adverse events encountered in the study. Ensure that the most clinically relevant ones are here (e.g., bleeding in anticoagulant trials).

Criticisms

  • Small sample size
  • Nonrandomized, retrospective analysis
  • Nonstandardized anesthetic management
  • Limitations in BP sampling/measurement (eg, pt's true baseline vs last recorded BP as model for anesthetic BP mgt w/in 10% of "baseline" value)
  • Statistically significant difference in baseline characteristics of the two groups

Funding

One or two sentences about how the trial was funded.

Further Reading

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