Prehospital Stroke Care 2

Cerebral Vascular Accident 

Clot or Bleed?

By Adam Thompson, EMT-P

The stroke patient is one that is commonly seen and transported by EMS providers.  There tends to be a frustration due to the inability to do much for these critically ill patients.  Their quality of life subsides right before our eyes.  There are two types of stroke as I explained in PART 1.  There are treatments available for ischemic strokes that can tremendously benefit the patients if given soon enough.  Thrombolytic therapy could be very effective in treating the ischemic stroke patient in the prehospital environment.  The only problem is that if this treatment was used on a patient suffering from a hemorrhagic stroke, it could tremendously worsen that patient's condition.  There is no way to conclusively differentiate between an ischemic or hemorrhagic stroke in the field without the use of diagnostic equipment.  There are, however, many indicators that could clue you in on the probably etiology.


Risk factors for stroke


Most of the risk factors for stroke are the same for both subtypes.  However, some are more indicative of a specific type.  Knowing these may assist you, along with the presenting signs and symptoms.

More associated with ischemic stroke

• Atrial fibrillation 
• History of TIAs
• Increase in Vitamin K
• Carotid artery disease
• High cholesterol
• Diabetes
• Patent Foramen Ovale

More associated with hemorrhagic stroke

• Severe acute hypertension
• Anticoagulant medications
• Smoking

Similar to risk factors, physical findings are not synonymous with a specific subtype, but they are very good indicators.  These signs may indicate either type of stroke, I cannot stress that enough.  


Signs of Hemorrhagic Stroke

• Airway compromise
• Complete unresponsiveness
• Complete aphasia
• Nausea & vomiting

Signs of Ischemic Stroke

• Expressive aphasia
• Unilateral deficits
• Poor coordination

So it is possible to have a fairly good idea weather the stroke patient you are presented with is suffering from a clot or a bleed, based on a fine assessment.  With advancements in technology, this skill, however, may eventually be unneeded.  There is solid evidence supporting the efficacy of paramedics and the use of prehospital diagnostic equipment.  There are portable brain scanners that are being tested in the field right now.  This may sound like something far-fetched or unnecessary, but I believe otherwise.  With stroke being the time is tissue condition, why not use equipment that may facilitate treatment that could subsequently improve the quality of life, of our patients.  With the ability to conclusively diagnose an ischemic stroke, thrombolysis could be preformed much earlier.  There would be an obvious need to provide research and gain evidence to support this process, but with an exponential probability of benefit, there should be a bigger push to get this done.  The studies advocating hypothermia in the presence of a CVA all appear encouraging as well.  Please read some of the research I have provided below.

Set up and run a thrombolysis service for acute stroke. [1]

Abstract 

Intravenous thrombolysis significantly improves the chance of independent recovery from ischaemic stroke but its benefit is strongly time dependent: present evidence supports effectiveness when delivered up to 4.5 h after symptom onset but the chance of recovery is twice as great when it is given within 90 min compared with 3-4.5 h. Delivery of treatment to a high proportion of patients is possible but requires clinicians to optimise systems for patient transfer, clinical and radiological assessment. A high proportion of patients with stroke already present to UK hospitals within the treatment time window even without specific public awareness or prehospital triage. Establishing a service requires dialogue with all those involved in the patient pathway, including ambulance dispatchers, paramedics, emergency department staff, radiology and colleagues in acute medicine. Most acute stroke teams cross traditional medical disciplines. Thrombolysis should ideally be delivered within an integrated service that seamlessly includes acute stroke unit care and rehabilitation.

Transcranial ultrasound from diagnosis to early stroke treatment. 1. Feasibility of prehospital cerebrovascular assessment. [2]

Abstract

BACKGROUND: To test whether portable duplex ultrasound devices can be used in a prehospital '911' emergency situation to assess intracranial arteries. METHODS: Non-contrast-enhanced transcranial duplex ultrasound studies were performed either immediately at the site of the emergency (i.e. private home) or after transfer into the emergency helicopter/ambulance vehicle. RESULTS: A total of 25 patients were enrolled. In 5/25 cases, intracranial vessels could not be visualized due to insufficient quality of the temporal bone window. In 20/25 cases, bilateral visualization and Doppler flow measurements of the middle cerebral artery could be assessed in a mean time less than 2 min. CONCLUSION: Emergency assessment of intracranial arteries using portable duplex ultrasound devices is feasible shortly after arrival at the patient's site. 2008 S. Karger AG, Basel.

A noninvasive portable acoustic diagnostic system to differentiate ischemic from hemorrhagic stroke. [3]

Abstract 

PURPOSE: To determine if a noninvasive brain acoustic monitor can differentiate acoustic responses from "normal patients" and ischemic from hemorrhagic stroke patients. METHODS: A laptop-sized passive acoustic monitoring system acquires arterial-pressure-generated signals during a 15-second monitoring session from sensors placed at the radial artery and on the fore-head. The arterial pulse waveform from the head is compared with that of the arterial waveform to generate the time-domain signal comparison. Frequency domain signals from each area are also compared. The study involved patients with diagnosis of first stroke who could be monitored within 12 hours of symptom onset and normal subjects who provided informed consent. Individuals with history of brain injury, stroke, or other brain disease were excluded. RESULTS: Twelve normal subjects and 6 ischemic stroke, 2 transient ischemic attack (TIA), and 3 hemorrhagic stroke patients were monitored. Frequency response analysis identified uniform frequency responses in normal subjects. The signal in ischemic stroke patients was characterized by a divergence of the radial and cranial frequency response between 10 and 50 Hz of 10 dB or greater. In intracerebral hemorrhage patients, a divergence was seen below 10 Hz but not in the band above 10 Hz. TIA patients were monitored after symptom resolution and showed a divergence <10 dB in both bands, similar to normal subjects. CONCLUSIONS: In a pilot study using a noninvasive monitor, the authors detected a potential to differentiate between normal subjects and those with cerebral ischemia or hemorrhage.

Comparison of neuroprotective effects in ischemic rats with different hypothermia procedures. [4]

Abstract

OBJECTIVE: The neuroprotective effect of hypothermia has long been recognized. The aim of this work was to compare the neuroprotective effect of systemic, head and local vascular cooling hypothermia procedures in ischemic rats. METHODS: Stroke in Sprague-Dawley rats (n=64) was induced by a 3 hour right middle cerebral artery occlusion using an intraluminal filament. Before reperfusion, ischemic animals (n=16 in each group) received hypothermia (systemic, head or local vascular) or no treatment. Brain temperature, infarction volume (n=8 in each group) and functional outcome (n=8 in each group) were compared. RESULTS: Regarding brain temperature, vascular cooling significantly reduced the temperature of ischemic territory in cortex from 37.2 +/- 0.1 to 33.4 +/- 0.4 degrees C and in striatum from 37.5 +/- 0.2 to 33.9 +/- 0.4 degrees C within 5 minutes. This hypothermic condition remained for up to 60 minutes after reperfusion. However, systemic cooling reduced brain temperature at a similar level for six times longer. In the head cooling group, the target temperature was reached in 15 minutes, but returned to normal within 5 minutes. Although all hypothermia procedures induced neuroprotection, ischemic rats with vascular cooling showed significantly (p<0.001) better neuroprotection with 10.7 +/- 2.6% infarction, compared to 54.2 +/- 1.9% (no treatment), 37.1 +/- 1.0% (head cooling) and 29.1 +/- 3.4% (systemic cooling). Significantly (p<0.001) better effects on motor function were also detected in vascular cooling groups at 14 and 28 days. CONCLUSION: Vascular cooling appears to be the most effective in reducing infarct volume and improving functional outcome than the other two hypothermia methods in a rat ischemia/reperfusion model.