The Daily Dose • Monday, May 20

MVPs for the Penumbra: Better Anesthesia Management of the Complex Stroke Patient

By Amanda Decimo, MSN, MPH, CRNA, from the IARS, AUA and SOCCA 2019 Annual Meetings*

Anesthesia providers play a critical role in the complex stroke patient’s journey through the hospital as they seek timely treatment for their cerebrovascular event. The panelists inspired audience members to become MVPs of the multidisciplinary stroke team in the SOCCA panel, Critical Care Anesthesiologist & Acute Care Continuum of Complex Stroke Patient, with Miguel Cobas, MD, FCCM, Jerrad Robert Businger, DO, Alexander C. Fort, MD, Phillip Vlisides, MD, and Ozan Akca, MD, held on Sunday, May 19.

Dr. Cobas, University of Miami and Jackson South Medical Center, provided an overview of acute stroke. Eighty-five percent of strokes seen will be ischemic, according to Dr. Cobas. These strokes are either small vessel occlusions (lacunar) or large vessel occlusions (carotid terminus, middle cerebral artery, anterior cerebral artery, vertebral, basilar, and posterior cerebral artery). Basilar strokes are associated with the worst outcomes.

The presenters referenced the 2018 Guidelines for the Early Management of Patients with Acute Ischemic Stroke for the presentation. The guidelines recommend an acute stroke team, and anesthesia needs to be a part of that for fast, early intervention. The team should be ready to move the patient through the different stages of acute stroke care. The panel recommended using a consistent stroke screening too, such as the NIH Stroke Scale (NIHSS), to determine patient stroke severity.

The first testing the patient needs is a plain brain CT scan and a blood glucose test. All other tests can wait, according to the panelists. Alteplase should be given in less than 3 hours. The criteria for inclusion is now more: At 3-5 hours, patients older than 80 and diabetics are excluded. Alteplase should be considered even with thrombectomy. Alteplase complications include hemorrhage and anaphylaxis.

Part of the initial rapid assessment includes airway, breathing, and oxygenation. Breathing is often normal, but airway protection mechanisms may be compromised. Intubation may be needed, in that case.

MAC vs. GA for Mechanical Thrombectomy?

A poll of the audience showed that a majority reported using Monitored Anesthesia Care (MAC) primarily and not general anesthesia (GA) for thrombectomies in their hospitals.

Why MAC and not GA? Time is brain. With sedation, we can move faster to the procedure. Awake patients offer the best neurologic monitor. There are less hemodynamic alterations. General anesthesia induction and extubation tend to involve blood pressure swings. And finally, sedation requires less resources.

Arguments in favor of general anesthesia are that once initiated, it provides more stable procedural conditions and a faster procedure. There are no mid-procedure surprises (airway issues, movement, restlessness, or agitation) with general anesthesia.

The presenters explained that there is no major difference in outcomes with general anesthesia is shown if the timeline from suite to needle puncture is minimized and aggressive blood pressure management occurs. Strict blood pressure adherence is needed either way. Choose either, and manage well, the presenters advised.

When deciding between Monitored Anesthesia Care and general anesthesia several key questions should be asked:

  • Is the patient responsive to verbal or tactile stimuli?
  • Can the patient lie supine without respiratory or aspiration concerns?
  • How is their oxygen saturation?
  • And finally, if a conversion to GA is needed, how easy will it be to secure the airway in suboptimal conditions?

If the answers to any of these questions is no, consider general anesthesia.

The majority of anterior circulation strokes can be easily managed under sedation. Posterior strokes (basilar artery) are more likely to have depressed neurological function and may need GA. The panelists stressed the importance of discussing the location of the thrombosis and how challenging they expect the procedure to be with the neurointerventionalist. If the procedure is likely to run over 30 minutes, consider general anesthesia.

Admitting the Post-Thrombectomy Stroke Patient

Where to admit acute complex stroke patients after thrombectomy is a clinical and financial concern. Consider this post-MAC thrombectomy patient: He has a GCS of 14, good blood pressure range, breathing well, with no infusions running. Should this patient go to the floor, stroke unit, or ICU?

A stroke unit is a dedicated hospital ward where stroke patients are cared for by a multi-professional team with specialist knowledge and training for stroke management. But it is not an ICU. It contains non-intensive beds and may contain intensive beds, which have continuous monitoring. An important point of distinction is that a neurointensivist will be managing the stroke unit if there are intensive beds; otherwise these units are managed by a neurologist.

Common post-thrombectomy complications relate to the significant neurologic deficits that these patients may have. Interventions sometimes required after IV tPa and thrombectomy include: management of uncontrolled hypertension, vasopressors for hypotension, invasive hemodynamic monitoring, life-threatening arrhythmias, insulin infusions, management of airway emergencies, and seizures.

When considering criteria for ICU admission following thrombectomy, the best data comes from the ICAT study, at Johns Hopkins School of Medicine, involving patients who had IV tPA for acute ischemic strokes. It showed that patients who had two or more predictive elements (male, black, spontaneous bacterial peritonitis criteria, NIHSS criteria) would have a 97% chance of needing ICU interventions. This may also have predictive value for post-thrombectomy patients and help guide decision making for ICU admission.

A study from 2015, published in Cerebrovascular Disease, looked at the beneficial effect of a stroke unit compared to the ICU. It found that patients who went to the stroke unit had more favorable outcomes at 3 months. Why? The stroke unit had better continuity of care, a harmonized neuro-rehabilitation program, and increased familiarity with stroke patients. It may be a better alternative for acute ischemic stroke patients with only “relative” indications for ICU admission.

Going back to the post-thrombectomy scenario, where to admit that patient depends on the individual hospital system and availability of a stroke unit. Guidelines recommend some form of more intense monitoring for the first 24 hours of post-thrombectomy.

Perioperative Stroke

The World Health Organization (WHO) declared in 2016 that stroke was the second leading cause of death worldwide. What about the perioperative setting?

The incidence of perioperative stroke is steadily on the rise. General prevention guidelines and management for perioperative stroke are lacking. Smilowitz et al. (2017) examined cardiovascular and cerebrovascular events after surgery. The study found stroke was rare in general surgery. With comorbidities, risk increases. The Neurovision group (2016) found that 10% of surgical patients in their study experienced either covert or overt cerebrovascular ischemia. Stroke may be occurring more often than health professionals realize during surgery.

Diagnosis of Perioperative Stroke

Saltman et al. compared in-hospital cerebrovascular accident (CVA) to community-setting CVA in his outcomes study. In-hospital stroke was associated with higher mortality, delayed recognition, and infrequent treatment. For non-cardiac surgical patients, median time from symptom recognition to neuroimaging was 5-8 hours. Thrombolysis therapy was rare. Delayed recognition of in-hospital strokes leads to high mortality.

Why do we see delayed recognition of perioperative stroke? Clinical detection in this period is challenging. Patients are still waking up from anesthesia, receiving pain medications, and some elderly patients experience postoperative delirium. Deficits are challenging to recognize.

The current four major biomarkers used for early stroke recognition demonstrate significant variability and are not clinically useful. Also, some stroke patients with significant cerebrovascular ischemia don’t show significant elevations in these biomarkers. Neurophysiologic evaluation with EEG may be helpful, particularly post-op in certain high-risk patients.

Prevention of Perioperative Stroke

Prevention measures should consider proper management of patients on beta-blockers and a high risk for perioperative stroke. Beta-2 blockade may impair cerebrovascular vasodilatation, which can be detrimental. When combined with blood loss, the incidence of ischemia goes up. It’s important to ensure blood loss is adequately replaced for patients with a high-risk of stoke and when taking beta-blockers.

Surgical scheduling can play an important part in the prevention of perioperative stroke. With a prior history of cerebrovascular accident, patients have an increased risk. If surgery is scheduled within 3-6 months of that stroke, the risk of perioperative stroke is very high. Risk levels out at about 9 months from the initial incident.

There is some debate over the practice of bridging patients on low-molecular-weight heparin (LMWH) during the perioperative period. Dr. Vlisides, University of Michigan Medicine, recommended: (1) low-risk patients with lower CHADS2  scores and no cerebrovascular disease history avoid bridging; and (2) high-risk patients with CHADS2 5-7 and known cerebral vascular disease history consider bridge therapy. There is an increased risk of perioperative bleeding and hemorrhage with bridge therapy, so risks and benefits need to be weighed carefully.

Anesthesiologist’s Role in Acute Complex Stroke Management

The anesthesiologist needs to act as the most valuable player (MVP) in acute complex stroke management. These players are scorers and leaders of the team. Good defensive players in anesthesia are safety advocates. They assist during critical moments inside and outside the OR.

Anesthesiologists need to watch the clock. Each 15-minute treatment delay leads to a 4% increased chance of permanent disability. The door to groin puncture goal is 90 minutes, and 120 minutes to reperfusion. For IV tissue plasminogen activator (tPA), the ideal treatment time is less than one hour from emergency department arrival.

Our role in anesthesia is patient safety. Sedation is not easy for thrombectomy. Cheyne-strokes breathing occurs in 25% of these patients, and that makes thrombectomy a challenge under sedation. SpO2 should be maintained >94%. If airway patency is compromised, general anesthesia is a better alternative.

Blood Pressure Management

How to perfuse the penumbra? Autoregulation is not happening in this salvageable tissue. Blood flow is pressure-dependent in the penumbra. How do we assure adequate blood flow? Permissive hypertension AHA/ASA guidelines for acute ischemic stroke include:

  • If not tPA candidate BP <220/110 mmHg
  • tPA candidate BP <185/110 mmHg
  • Do not aggressively lower BP (with 15%)

The Society of Neuroscience in Anesthesia and Critical Care (SNACC) guideline includes spontaneous bacterial peritonitis (SBP) between 140 and 180mmHg and a MAP>70mmHg .

Dr. Akca, University of Louisville Hospital, shared his own data comparing good outcomes to bad outcomes for patients who had mechanical thrombectomies. Overall, there was a 5-10mmHg higher MAP during the procedure in patients with good outcomes. Even a small difference in MAP for a duration of time matters.

The panel concluded with a Q&A period, offering advice to maintain a niche in your hospital for quality stroke care. A greater volume of acute ischemic stroke patients at your hospital will result in improved care. Be on top of the blood pressure, the presenters emphasized. More research is on the way for blood pressure management and ischemic stroke.

Several recently published articles in Anesthesia & Analgesia review these important concepts:

  1. Anesthetic Management of Emergency Endovascular Thrombectomy for Acute Ischemic Stroke, Part 1: Patient Characteristics, Determinants of Effectiveness, and Effect of Blood Pressure on Outcome.
  1. Anesthetic Management of Emergency Endovascular Thrombectomy for Acute Ischemic Stroke, Part 2: Integrating and Applying Observational Reports and Randomized Clinical Trials

*Coverage from SOCCA Panel: Critical Care Anesthesiologist & Acute Care Continuum of Complex Stroke Patient during the IARS 2019 Annual Meeting