I refer you to this article in the British Journal of Anaesthesia by Anastasian:
For these patients the time from acute ischemic stroke (AIS) to endovascular intervention is critical. The goal is the treat these patient within 4-6 hours of the onset of symptoms.
The issue is to preserve as much of the so-called “penumbra” surrounding the stroke as possible. The goals with AIS are similar to those for traumatic brain injury (TBI); maintain oxygen saturation and adequate blood pressure to perfuse the threatened but viable brain tissue surrounding the injury.
It is my opinion that AIS is similar to TBI and the goals for managing it are similar to those for TBI; maintain a high systolic blood pressure and an oxygen saturation above 90% (see blog posts on TBI). However, the goals for the systolic blood pressure range in AIS are much higher than promulgated for TBI (see below).
The issues for the management of these patients is a preferred (but unknown) method of anesthesia. Over the last few years, a number of retrospective studies suggest that the outcome with general anesthesia is worse than with local/sedation. The pros and cons of both are:
Click tables to enlarge them.
These are the retrospective studies that suggest that general anesthesia may worsen outcome:
You may read the entire Anastasian article here:
Here is the long story, short:
- Endovascular treatment is generally not a painful operation. The painful part is the groin stick, which can be manage with local anesthesia. There are some painful portions during the intracerebral manipulations that could cause the patient to move. Many patients who can remain motionless during the procedure can be managed with just sedation.
- One of the reasons that general anesthesia may be associated with worse outcome in AIS is that general anesthesia may have been required to control movement/pain in the patients with high National Institutes of Health Stroke Scores. These patient could be predicted to have worse outcomes regardless of the type of anesthesia.
- General anesthesia, more so than sedation, can profoundly lower blood pressure. It is these blood pressure drops owing to general anesthesia that have been implicated in worsening outcome. A plan must be in place to insure that blood pressure is maintained from induction to the end of the anesthetic. Please see the post:
What can anesthesiologist do to improve outcome in AIS?:
- Time is brain. We need to respond as rapidly as possible in order to minimize the symptoms-to-groin-puncture interval.
- We need to diligently monitor the blood pressure during our time with the patient and maintain the systolic blood pressure between 140-180 Torr regardless of the type of anesthesia used.
- We need to maintain an oxygen saturation above 90%. 100% is desirable.
There is a randomised clinical trial of general anesthesia versus sedation in progress in Sweden. The study arms consist of “sevoforane + remifentanil” vs. spontaneous breathing with remifentanil alone. I emailed the PIs regarding the protocol for administering these agents this is their reply.:
- Basically, the general anesthesia group is induced with propofol and rocuronium for intubation and maintained with remifentanil and sevoflurane, dosages/end-tidal concentrations at the discretion of the attending anesthesiologist.
- The conscious sedation group receives only remifentanil infusion with boluses of propofol/midazolam if needed.
Details of this trial can be found at:
Hopefully, this trial, which is slated to be completed this year, will provide us with the guidance we need to better take care of AIS patients.
I’ve recently learned of yet another trial being conducted in Denmark that bears on this problem:
- For general anesthesia these investigators use propofol/remifentanil and rapid sequence intubation with suxamethonium.
- For conscious sedation they use fentanyl 25-50 ug and propofol 1-2 mg/kg/hr. The infusion rate and amount of fentanyl is titrated to the level that the patient remain calm and is still able to communicate (patent airway). If they have any problems maintaining a sufficient blood pressure (MABP > 70 mmHg and systolic > 140 mmHg) they use phenylephrine as 1st choice.