test 9 continued Flashcards
Morbid Neurological Outcomes type 1
Cerebral Death
Non-fatal strokes
New Transient ischemic attack (not causing permanent damage but is an indicator for bad things down the road)
Morbid Neurological Outcomes type 2
New intellectual deterioration
New seizures upon discharge (more seizures after surgery)
Type I Predictors
Advanced age is the single greatest
< 60 : 1% risk
> 70 ; 4 to 9% risk
Aortic atherosclerosis (calcified aorta)
History of prior neurologic events – 15%
Carotid stenosis
# of GMEs
Type II Predictors
Low cardiac output states/hypotensive states
GMEs (size)
Atrial arrhythmias
Systolic Hypertension
Diabetes mellitus (lack of control of glucose)
Pulmonary Disease
Excessive Alcoholism
Prevalence of CVS Complications
Neuro Impairment: 6.1% (stroke, coma, seizures)
Post-Op Delirium: 10-60%
-neurologic dysfunction after bypass results in a longer length of stay
-post-op psychometric testing scores 100%
when does the Incidence of Neurologic Dysfunction happen most in surgery (single greatest neurological stress)
-filling of the heart because there are many pocket inside the heart that have chances of bubbles
Surgical Technique to decrease Atheroembolism
Epiaortic ultrasound
Single Cross Clamp
No touch techniques
Paying attention
How do Perfusionists
Contribute
Focal (embolism)
Hypoperfusion
Inflammation
Global
How do Perfusionists
Contribute globally
Complete Cardiac Arrest Deep Hypothermic Circulatory Arrest Incomplete Hypotension Inadequate CPB flow
Factors Affecting Blood Oxygenation
- Tailoring Oxygen Delivery
- Tailoring Oxygen Consumption
Tailoring Oxygen Delivery
- Mean Arterial Pressure
- CO2
- Cardiac Index and Pump Flow
- Hematocrit
- Mechanical Issues
Tailoring Oxygen Consumption
- Anesthetic Agent and Depth
* Temperature
Brain Monitoring
Neurological exam
Blood Pressure monitoring (doesn’t tell what is actually happening)
EEG – Electroencephalogram
BIS – Bispectral Index
TCD – Transcranial Doppler
ICP – Intra-cranial pressure monitoring
SjVO2 – Saturation of Jugular Venous Oxygen
SvO2 – Saturation of Venous O2 (global)
rSO2 – REGIONAL SATURATION OF OXYGEN
Ways to help prevent brain injury
EEG: Electroencephalogram
BIS Monitoring: Bispectral Index
Cerebral Oximetry
What is an Electroencephalogram (EEG)?
- large footprint so rarely used
- a lot of leads and need someone to read it
- reads electrical activity on the surface of the brain but does not measure what is going on deeper in the brain
Alpha and Beta waves of EEG
-patient is awake
Theta and Delta waves of EEG
- patient descends into sleep or a coma
- are not normally seen in awake patients unless pt has past cerebral injury
common abnormalities of EEG waves
15% of population show abnormalities due to old injuries
Clinical Usage
Main Reason EPILEPSY (number 1 usage) Brain Tumors Stroke Focal brain disorders Secondary reason Diagnosis of coma Encephalopathies Brain death
Disadvantages in the OR
Analysis is complex
Distracting anesthesiologist from patient care
any other electrical activity will affect this (machinery, skeletal and cardiac myofibrils)
Bispectral Index (BIS)
Processed EEG information as a measure of sedative effects of anesthesia medications
Information displayed every 10-15 seconds
Graphical trend and numerical value
-cheap and easy to interpret
BIS Monitoring
Allows anesthesia the ability to access the complicated EEG information during the case
Uses easy numbering system to identify depth of anesthesia
How does bispectral index work (4 things correlated)
- degree of high frequency activation
- degree of low frequency synchronization
- degree of periods near suppression
- degree of periods completely suppressed
BIS index
The index is a number
between 1 and 100 (100= wide awake)
Association between clinical states and BIS values
100 Awake 80 Light/Moderate Sedation 60 General Anesthesia 40 Deep Hypnotic State 20 Burst Suppression 10 Flat Line EEG -a BIS below 70 the pt will not remember things
Target BIS values
Need to be tailored for each individual
Using opioid anesthesia (40-60)
Using opioid anesthesia on pump (Normally 25 to 35, TARGET to titrate to 45 - 55)
If the BP starts to increase, what is another thing you could do other than turn down your flow
-turn up the gas anesthetic
Why is the BIS important to us
BIS helps us maintain our hemodynamics (doesn’t tell a lot about the brain)
Reduction in primary anesthetic use
Reduction in emergence and recovery time
Improved patient satisfaction
Disadvantages of BIS
It is a trending device
We can’t be responsible to treat the level of sedation
Often monitor only faces anesthesia
Transcranial Cerebral
Oximetry
measures not only surface, but down into the brain. Non-invasive and measures the oxygen metabolism in terms of how much oxygen the brain is pulling off of each hemoglobin.
The INVOS System clinical benefits
Noninvasive, continuous, direct, real time measurements of the oxygen hemoglobin extraction done by the brain
Site-specific (regional) measure vs systemic; often signals earlier warning of reversible ischemia
Need to set a BASELINE otherwise you don’t know if you are high or low
Not a trending device, it tell you if have a problem
Major improvement on Major Organ Morbidity or Mortality percent
Adult Applications of INVOS to Date
Cardiac surgery Vascular surgery Cardiac cath lab Neurology / Neurosurgery ER / traumatic brain injury General surgery Spinal injury
Pediatric Applications of INVOS to
Date
Cardiac surgery
ECMO (Extracoporeal Membrane Oxygenation)
Cardiac Cath lab (at times)
Neurology / Neurosurgery
Still being studied – must convince the caregivers that
the data is useful
Sensors are improving (much work to do)
Placement of the Sensors
- Clean area with alcohol - let it dry
- Attach sensors above the eye brows
- Connect to machine
- SET BASELINE (very important to set baseline before anesthesia induction and nasal oxygen)
How optical technology works
- Infrared shoots through the head and the different levels of oxygenated hemoglobin absorb the infrared light
- it tracks out the surface absorption and the deeper absorption
INVOS measures adequacy of cerebral perfusion giving you
- supply of blood to the brain
- supply of O2 to the brain
- any inflow or outflow obstructions
Cerebral Inflow Issues
- Head Position
- Heart Position
- Arterial Obstruction (Carotid Disease, Clamp, Hand, Sponge)
- Cannula Malposition
- Cerebral rSO2 detects O2 supply issues associated with inflow obstructions
- rule out mechanical cause (head position or cannula position)
- Cerebral rSO2 detects O2 supply issues associated with oxygen delivery
- Increase blood pressure
- Increase FiO2
- Increase cardiac output (pump flow)
- Increase hematocrit
- Cerebral rSO2 detects
O2 supply issues
associated with
oxygen delivery: decrease demand (cerebral metabolism)
- Increase anesthetic
- Decrease temperature
cerebral supply issues
- Low FiO2
- Low Hgb
- Low MAP
- Pump Flow
- Spasm
rSO2 Target & Thresholds
Intervention threshold
-rSO2 < 50 or 20% drop
from baseline
-need to start making people aware
-look at the 3 step algorithm
rSO2 Target & Thresholds
Critical threshold
-rSO2 < 40 or 25% drop
from baseline
-longer your values below critical thresholds, are related to your cerebral outcomes
Regional Oximetry
- not invasive
- not just trending values, actually gives real time things that are happening
What you can do to protect your patient’s brain?
Medical History
Monitor for cerebral ischemia
Use filters on heart lung machine for embolic phenomena
Use glucose free fluids to avoid significant hyperglycemia
Maintain controlled temperature
Maintain appropriate perfusion pressure and flow during CPB
Consider pharmacologic brain protection
Utilize brain hypothermia during periods of reduced flow or perfusion pressure
Perform left ventricular de-airing methods
Ensure high normal postoperative blood pressures