Summer Final Exam Flashcards
Highest Occurence of recall
General surgery
Diagnostic criteria for PTSD
Both: a)person witnessed, experienced or was confronted with an event or events that involved actual or threatened death or serious injury or threat to physical integrity of self or others b) the person’s response involved intense fear, helplessness or horror
Of 26 patients with awareness in study ___ had no post-op sequelae
8
Percent of recall due to faulty anesthetic technique
70%
Percent of recall due to failure to check equipment
20%
Goals of satisfactory anesthetic
1) Adequate perfusion of all organ systems 2) unresponsive to noxious stimuli 3)no awareness or recall of events during procedure
Cortical Phenomenon
Consciousness (controlled by hypnotics)
Poor indicators of consciousness
Subcortical phenomenon: movement (cord reflex), hemodynamic response (brain stem)
Depth of anesthesia can be defined
by suppression of clinically relevant responses to noxious stimuli
Analgesic
Agent that relieves pain w/o loss of consciousness
Amnestic
agent that results in loss of memory of an event or time period
Hypnotic
an agent that produces drowsiness and acts to induce sleep or sleep like state
Sedative
an agent that allays excitement and produces a calm state
Muscle relaxant
an agent which blocks the transmission of nervous impulses to skeletal muscle, rendering patient paralyzed and unable to breathe or move
Tranquilizer
agent that quiets or calms patient w/o affecting clarity of consciousness
Anxiolytic
agent that relieves apprehension and fear, relief from anxiety
Most commonly used measurements for monitoring anesthetic depth
HR and BP
Explicit Knowledge
easily recalled and explained
Implicit knowledge
cannot consciously recall, influences our behavior
Tracheal intubation is about ___ as stimulating as skin inscision
twice
Most anesthesiologists rely on ___ to assess anesthetic depth
their clinical experience and the dose of anesthetic
Isolated arm method
Blood pressure cuff inflated high, patient is relaxed and anesthetized. Patient is told to squeeze. Some patients respond even though all other signs would indicate anesthetic depth
MAC that we typically use
ED50
Doses minimally larger than ED50
prevent movement
concentration response relation for inhaled anesthetics is steep
So, ED95 differed minimally from ED50
MAC is mediated at subcortical levels so..
Because the cortex is more sensitive MAC is at a higher concentration than is really needed. The concentration of anesthetic needed to cause unconsciousness is much lower
Factors that increase mac
Hyperthermia, hyperthyroidism, alcoholism, acute administration of dextroamphetamine, young age
No effect on MAC
duration of anesthesia, sex, metabolic acid-base status, hyper/hypocapnia, isovolemic anemia, HTN
Redheads require ___ more anesthesia on average than brunettes
20%
Work practices
Vigilance, fatigue management, seeking advice
For the intraoperative phase
Scan equipment regularly during each case, take care to avoid wrong drug admin., give adequate hypnotic drug where possible, minimize use of muscle relaxants, respond rapidly to suspected inadequate anesthesia, modulate OR behavior, consider using EEG based monitor
BIS
Bispectral Index system
Differential amplifier measures potential difference between electrodes 2 and 3. Electrode 1 is the ground (reference). Electrode 4 is used in noise reduction.
EEG
represents cortical electrical activity, continuous, responsive, noninvasive indicator of cerebral fxn
BIS XP
sensor with additional electrode (#4), electrosurgery resistant, enhanced detection of near suppression
Density Spectral Array (DSA)
graphical representation of EEG frequency differences between the 2 hemispheres
Derivation of BIS
30, 1 second epochs of frontal EEG, empirical technique is statistical multivariate regression, uses Entropy
Burst suppression ratio
extent of electrical silence (0 active 100 silent)
Relative alpha/beta ratio
8-13 Hz energy/ 13-30 Hz energy
Bicoherence of EEG
degree of phase coupling between individual waves
BIS range
0 to 100. 0 is unconscious, 100 is fully awake
SQI (signal quality index)
ranges from 0-100%. This is the % of good epochs in the last 60 that could be used for calculation of the BIS.
EMG
electrical power in the 70-110 Hz range (given in dB with trend and bar graph)
SR (suppression ratio)
% of epochs in past 63 seconds in which EEG signal is considered suppressed
SEF (Spectral edge frequency)
the frequency at which 95% of total power lies below and 5% lies above
BIS responds more ___ to an emergence than spectral edge frequency
rapidly
EMG signals
tend to increase BIS number artifactually
Hypothermia and ischemia
appear identical to deep sedation and decrease BIS number
BIS responds better to
Halogenated agents and propofol than to N2O and Ketamine
Prevention of implicit memory at BIS of
84-91
Awareness estimate
0.2-0.4% for elective and emergency surgery
BIS does NOT
predict movement or hemodynamic response
BIS index is designed
to measure the effect of hypnotic anesthetic drugs.
When patients move during surgery with a BIS below 60,
additional analgesia may suppress further movement
In BIS movement trials,
Small opioid doses DID blunt surgical responses, and large hypnotic doses DID NOT eliminate surgical responses
Hypothesis from BIS movement trials
Movement/autonomic responses correlate with analgesia and EEG changes correlate with hypnosis/consciousness
BIS must be used
in conjunction with traditional vital sign monitoring
Entropy
describes irregularity, complexity or unpredictability characteristics of a signal
When the patient is awake,
EEG is highly irregular and the amt of entropy is very high. As the pt goes into deeper planes of anesthesia, EEG will have a more regular pattern of wave forms which brings down entropy
State Entropy
cortical, steady and robust
Response Entropy
muscle, fast reacting
PSI
Patient State Index. 25-50 optimal hypnotic state for general anesthesia
Entropy range of 40-60
Clinically meaningful anesthesia with low probability of consciousness
For control-a-flo: Maintain vertical distance of ___ or greater from container fluid level to venipuncture device
75 cm (30”)
Infusion pump types
Peristaltic (rotary or linear), cassette, elastomeric reservoir, syringe
Cerulean blue clamp pump (linear peristaltic?)
+/- 5% accuracy
Bard Infus O.R.
Infusion: linear rate +/- 3% accuracy, Bolus: linear displacement +/-3%
In syringe infusor, a 20 cc syringe will give ___ that of a 60 cc syringe
half
BET scheme
Bolus, Eliminated (continuous infusion to replace drug eliminated), Transferred (exponentially declining infusion to replace drug transferred out of plasma to other body compartments)
PCA (patient controlled analgesia) advantages
patient autonomy, rapid relief of pain, analgesia/dosage tailored to patient’s requirements with patient able to balance analgesia and side effects
Key Points to PCA system
route of admin, type of admin, ease of programming, ease of priming, power source, safety, security, portability, display, printout
Who painted 3 ages of woman?
Gustav Klimt
Blood volume of mother at term
35% increase
Plasma volume of mother at term
45% increase
Erythrocyte volume of mother at term
20% increase
Blood platelets of mother at term
unchanged
A non-pregnant woman should have a hematocrit of about 40% but because plasma volume ____ more than RBCs ____, HCT at term is about ___.
increase, increase, 35%
Minute ventilation at term
+50%
Alveolar ventilation at term
+70%
Tidal volume at term
+40%
Respiratory rate at term
+15%
Closing volume, arterial pH, Vital capacity, inspiratory lung capacity, and total lung capacity at term
unchanged
Arterial PO2 at term
+10 mmHg
Arterial PCO2 at term
-10 mmHg
Airway resistance at term
-36%
FRC, Expiratory reserve volume and residual volume at term
-20%
Oxygen consumption at term
+20%
Normal fetal heart rate
120-160 beats per minute
NST
non stress test-FHR and movement monitored over 15-60 minute period. We want to see variability and accelerations= negative NST
CST
contraction stress test, FHR monitored over 10 minutes w/ 3 contractions: induced vs non-induced. We want to see variability and accelerations=negative CST
BPP
biophysical profile: Fetal breathing, body movements, tone, heart rate reactivity and amniotic fluid volume
Fetal Oxygen Sat
Monitored by fetal scalp probe: SpO2 < 30% is concerning
Normal fetal scalp blood gases
pH=7.25-7.35 (mean umbilical artery pH=7.26), SaO2=30-50%, PO2=18-22mmHg, PaCO=40-50 mmHg
High apgar score
correlates to near normal pH (64.4%?)
Ways to measure fetal HR
fetal electrode, doppler ultrasound transducer, external abdominal ECG, phonocardiogram
Classes of HR variability
No FHR variability-range undetectable, Reduced FHR variability-range 0-15 bpm
tocograph
graphs fetal HR compared with fetal contractions
Sign of normal fetal oxygenation
accelerations with contractions
Bad deceleration patterns
Head compression- early deceleration (usually progresses to late deceleration), uteroplacental insufficiency-late deceleration (also indicates Hypoxia), umbilical cord compression- variable deceleration (indicating transient asphyxial myocardial failure w/ lack of HR variability indicating decreased cerebral oxygenation)
APGAR Score
Activity, Pulse, Grimace(reflect irritability), Appearance (Skin color), Respiration
WIKI
What I know is
Bedside point of care(POC) testing- Mandated by joint commission on accreditation of healthcare organizations
must be coordinated by department of pathology
Advantages of POC testing
enhanced decision making, improved clinical outcomes, reduced turnaround time, increased patient satisfaction, reduced length of stay
Locations where point of care testing options are helpful
Emergency room, ICU, Coronary care unit, obstetric suites, neonatal intensive care unit, burn unit, trauma room, OR
Potential testing options in OR
Blood sugar, H/H, coag,platelet function,creatinine kinase, troponin t, arterial blood gas, electrolytes, calcium, magnesium
Potential testing options in PACU
Blood sugar, H/H, coag,platelet function,creatinine kinase, troponin t, arterial blood gas, electrolytes, calcium
Potential testing options in ICU/CCU
Blood sugar, H/H, coag,platelet function,creatinine kinase, troponin t, arterial blood gas, electrolytes, calcium, magnesium, bacteriologic POCT
Issues influencing the introduction of Point of Care testing
Personnel and training, quality control, Proficiency testing( frequency, methodology), calibration verification, certification and inspection, records and documentation, integration with central laboratory
Disadvantages of POC testing
innacuracy, difficult controls and calibrations, training requirements
Chief uses of POC testing
Blood glucose analyses, blood gas analyses, critical electrolytes, H/H, coagulation, myocardial markers, urinalysis, pregnancy
CGB in Istat tests for:
Na, K, Ca, Glu, H/H, pH, PCO2, PO2, TCO2, HCO3, Base excess, sO2
Analyzers
evaluate blood permanently withdrawn from the patient (takes blood away, doesn’t give it back)
Monitors
Evaluate blood constituents by means of a probe exposed to circulating blood (looks at blood but gives it back)
Electroconvulsive therapy requires
Hypnotic, NMB, airway/bite block
Amount of fluid needed to drop patient temp by 1 degree C
4 liters
2 main problems with MRI facilities
high fixed magnetic field strength always present, high power pulsed radio frequency fields used during scanning
MRI scanner strength
1.5-4 Tesla, 10000 Gauss= 1 Tesla, Earth’s magnetic field is 0.5 to 1 Gauss.
MRI hazards
Projectile effect, twisting, burns, image artifacts, device malfunction
ECG in MRI
burn risk- Proper for is to have 4 electrodes placed over heart
Leads V5 and V6
maximize QRS and minimize artifact
Capnography in MRI
Artificially high inspired and low exhaled CO2 if line length is long and sample flow rate is low
Temperature monitoring in MRI
should be limited to liquid crystal strips, thermistors in orifices present a burn risk
Metal in MRI
must be non-ferrous (such as aluminum). Steel will get pulled in.
Heat dissipation can be measured by
Heated wire anemometer (has hot wire made of platinum or tungsten. One wire measures flow and the other wire determines effects of various gases during no flow)
Pressure gradient is measured by
Pneumotachometer
Calibration in a thorpe tube
should be read from the top of the float
Cerebral O2 consumption
3.5 ml/100g/min
CBF
50ml/100g/min
Respirometer locations
upstream or downstream of unidirectional valve
Flow volume loop moved down and right
decrease in compliance
Open flow volume loop
indicates gas leak either from deflated ett cuff or poorly seated lma
Nafion
H2O absorbing
When atmosphere surrounding patient’s deadspace
CO2 levels of inspired and expired air increase
Stethoscopy
non-invasive assessment of heart and lung sounds
Types of Stethoscopy
monaural, binaural, precordial, pretracheal, esophageal, doppler
Esophageal stethoscope should be placed
Around 30cm
R wave envelope
Inspiration increases R-wave amplitude.
Skin temperature contributes about ____ to control
20%
Interthreshold range in humans
0.2 degrees celsius
Cold receptors:non-cold receptors
10:1
Thermal sensors
hypothalamus, skin, deep body tissue receptors
BMR loss
Radiation- 65%, Convection-25%, Evaporation-10%, Conduction-negligible
After 1 hour of anesthesia, core temp
decreased 1.6 degrees celsius
The temperature in the esophagus may vary up to
4 degrees celsius
Esophagus temp probe
38-42 cm from incisors
Cooling and rewarming
occurred more rapidly in esophagus. Rewarming also occurred more rapidly in the nasopharynx
Wakefulness (eeg)
desynchrony
sleep (EEG)
synchrony
Ways to monitor brain fxn
EEG (processed-spectral edge, power spectrum), MEP (cortical), SEP (VEP, BAEP,SSEP), Wakeup
Rolandic Fissure
C3,CZ, C4
Montage
electrodes used during monitoring
Delta
<4 Hz, deep anesthesia
Theta
4-7 Hz light sleep, light anesthesia
Alpha
8-12 Hz
Beta
> 12Hz Mental activity, sedation, light anesthesia
Abnormal EEG
CBF <20-25 ml/100g/min
Cellular survival threatened
CBF < 12ml/100g/min
Deep anesthesia and Ischemia
produce same EEG pattern
Burst suppression of EEG
used during aneurysm clipping
Amount of total energy consumed in brain by neurons during depol and repol
Half
Increased EEG frequency
Hyperoxia, Initial Hypoxia, Small dose barbiturates, 30-70% N2O, Inhalational agents <1 mac
Decreased EEG frequency, increased amplitude
Mild Hypoxia,Inhaled agents >1 mac
Decreased EEG freq, decreased amplitude
Marked Hypoxia
EEG electrical silence
Severe Hypoxia
BSR
Burst suppression ratio-eeg derived variable, % of time in EEG sample that waveform is isoelectric
Variables for EEG changes during anesthesia
Mean, median, spectral edge
