RE 3- 17 Flashcards
What is “sweeping”?
systematic visualization of anesthesia field from machine to patient
Which standard is the AANA Scope and Standards for Nurse Anesthesia Practice
Standard V
What type of events occur most often?
respiratory
What are the main areas of AANA Standard V? (4)
ventilation oxygenation cardiovascular temperature neuromuscular positioning
What is AANA ‘s standard for continuous ventilation monitoring?(3)
1) Verify ETT by auscultation, chest excursion, and EtCO2
2) continuously monitor EtCO2 during controlled/assisted breathing or artificial airway
3) use spirometry and ventilatory pressure monitors as indicated
What is AANA’s standard for continuous oxygenation monitoring? (3)
clinical observation
pulse oximetry
ABG if indicated
What is AANA standard for continuous CV monitoring?
EKG and heart tones
Record BP and HR at least Q5m
What is AANA standard for neuromuscular monitoring?
when NMB used
What is AANA standard for monitoring temperature?
all peds receiving GA
when indicated in all other patients
What is AANA standard for assessing patient positioning?
assess and institute protective measures
Airway observations include:
chest movement airway obstruction: retractions, seesaw motion condensation feel of subtle air movement sense of smell for disconnected circuit airway sounds: stridor
Above all, what airway parameter should be observed?
minute ventilation
* Resp rate alone isn’t accurate to determine ventilatory status**
T or F Skin color alone is a reliable measure of adequate ventilation and oxygenation
F
What is a late sign of anemia and hypoxia?
cyanosis
What do ABGs assess?
ventilation and metabolic status
Is an ABG a direct or indirect measure of ventilation and metabolic state?
direct
The measure of CO2 in the blood is based on what?
H+
Bicarbonate buffer system reaction =
CO2 + H20 <> H2CO3 <> H+ + HCO3-
What do colorimetric EtCO2 devices detect?
What can cause false positives? (3)
carbonic acid via pH change
False positives= CO2 forced into stomach, carbonated beverages, or antacids
How many breaths are needed for accurate reading on disposible EtCO2?
6
What is the most common means of monitoring CO2 levels in anesthesia?
continuous electronic measurements of expired CO2
How does EtCO2 relate to arterial CO2?
ETCO2 is ~ 2 to 5 torr lower than arterial CO2 in patients without cardiac or pulmonary abnormalities.
Define capnogram.
continuous display of CO2
How does continuous CO2 monitoring work?
Infrared analysis-Each gas absorbs infrared radiation at a different wavelength.
Older monitors have difficulty distinguishing between CO2 and _.
nitrous oxide
Nondiverting CO2 sampling is know as_.
mainstream
Diverting CO2 sampling is known as _.
sidestream
Nondiverting CO2 sampling advantages.
minimal sample-time delay
few disposable items
no scavenging
Nondiverting CO2 sampling disadvantages _.
Can’t measure gases other than CO2 and nitrous
increase circuit deadspace
interference by condensation and secretions
traction on tube- circuit disconnect
can’t sample nonintubated patients
Diverting CO2 sampling disadvantages.
need to scavenge
contamination by condensation/secretions
Diverting CO2 sampling advantages.
minimal increase in deadspace
versatility in gas analysis (sample can be sent to agent monitors)
adapted to awake patients spont ventilating
T or F Sampling EtCO2 in Spont Vent patient’s hyopharynx is not reliable or accurate.
F
T or F EtCO2 has shown to be a more sensitive indicator of hypoventilation than clinical observation or pulse ox during sedation.
T
Discuss phase 1 of capnogram.
A-B
baseline
end of inspiration to the beginning of expiration
gas from anatomic deadspace with no CO2
Dicuss phase 2 of capnogram.
B-C
expiratory upstroke
mix of deadspace and alveolar gas
rapid passing of initial expired gas through upper airways
Discuss phase 3 of capnogram.
C-D
plateau, alveolar emptying
very nearly flat
longest duration
What part of the capnogram is EtCO2?
D
end of of the plateau just prior to inspiration
Discuss phase 4 of capnogram.
D-E
rapid decrease in CO2
inspiration
should return to nearly 0
When are EtCO2 measurements inaccurate?
significant ventilation/perfusion mismatches
When v/q ratio is large= ____ in deadspace causes a ____ concentration of EtCO2.
increase, low
How do small tidal volumes affect EtCO2?
Reflects inadequate alveolar ventilation can underestimate arterial CO2
Describe rebreathing CO2 waveform and causes.
fails to return to baseline
inadequate FGF or depleted soda lime
What does a sloping of the plateau phase mean on CO2 wave? Causes?
progressive prolongation of expiration
COPD, kinking ETT or tubing, obstruction or VQ mismatch
Describe cardiac oscillation on CO2 wave.
regular, sawtooth waves within expiratory phase
heart contractions force gas in and out
common in pediatrics dt size of heart to thorax
Describe a curare cleft and causes?
irregular asynchronous waveform
spontaneous effort r/t insufficient anesthesia or paralytics
Causes increase or decrease ETCO2 levels
T or F Transcutaneous CO2 monitoring provides immediate, breath by breath verification of ETT placement.
F
How does transcutaneous CO2 monitoring work?
measures the change in H+ beat to beat
When is transcutaneous CO2 monitoring beneficial?
ventilation/perfusion mismatching
severe obesity
OLV
when EtCO2 not practical (awake pt spont vent)
What is most helpful in assessing acid-base balance and respiratory function?
ABG
Clinical observation of oxygenation includes:
skin color and temperature nailbed perfusion signs assessment of depth and rate of respirations auscultation assessment of upper airway patency
How does pulse oximeter work?
transcutaneous measurement using a spectrophotometer to determine SpO2.
Oxygenated Hgb absorbs infrared light at diff wavelength then deoxygenated Hgb.
Measures amt of Unabsorbed red light via photosensitive diode.
Measures change in transmitted light during pulsatile flow (drop in light intensity w/each beat)
Is most O2 in the body carried bound or unbound?
bound
Oxygen carrying capacity is mainly dependent on _.
amount of Hb
What is the oxygen carrying capacity of Hb?
1.34 ml/g of Hb
What is the dissolved oxygen constant?
0.003 ml O2 / 100 ml blood at PaO2 100 mmHg
What does CaO2 stand for?
total arterial oxygen content
What is the equation for CaO2?
(0.003 x PaO2) + (1.34 x Hb x SaO2)
What determines the amount of O2 that binds to Hgb?
PaO2 of plasma
What two things is actual O2 delivery depend on?
oxygen content and CO
What does oxygen saturation measure?
portion of Hb bound to O2, not the dissolved O2 in blood
What does the oxyhemoglobin dissociation curve represent?
relationship between oxygen tension and percent oxygen saturation
What is on the x and y axis of oxyhemoglobin dissociation curve?
x- PaO2
y- SpO2
What is special about a PaO2 50 mmHg on oxyhemoglobin dissociation curve?
The amount of SpO2 rapidly increases per increase in PaO2 and then slows thereafter
On the oxyhemoglobin dissociation curve, what does a PaO2 of 60 mmHg correlate to?
PaO2 of 40 mmHg =____%SpO2
60=SpO2 90%
40= SpO2 75%
Discuss a right shift in oxyhemoglobin dissociation curve. Causes?
more ready release of O2 to tissues Elevated CO2 elevated temperature elevated 2,3-DPG Decreased ph, acidosis, elevated H+
Discuss a left shift in oxyhemoglobin dissociation curve. Causes?
greater attachment of O2 to Hb, decrease to tissue decreased CO2 decreased temperature decreased 2,3-DPG elevated ph, alkalosis, decreased H+
Discuss pulse oximetry accuracy.
within 2% if SpO2 80-100%
within 5% SpO2< 80%
Methemoglobin absorbs light equal to _.
oxyhemoglobin
Discuss the effect of methemoglobin on SpO2?
falsely underestimates when SpO2 >85% and falsely overestimates when SpO2 <85%
What effect does carboxyhemoglobin have on SpO2?
overestimate SpO2
List factors that can affect pulse ox reading?
methemoglobin carboxyhemoglobin sickle cell rare anemias methylene blue indigo carmine
List other uses for pulse oximetry.
determining SBP locating vessels determine presence of PVD changes in sympathetic tone degree of regional block
Earlobe pulse oximetry is a sensitive measure of ____.
systemic circulation and SV bc it is not affected by changes in sympathetic tone
** ear lobe is effected by change in pulse pressure**
What percentage of postoperative patients experience some degree of hypothermia?
70%
List hypothermia risks with anesthesia.
wound infection delayed healing increased O2 consumption with shivering increase risk CV and MI events increased sickling prolonged PACU time = increased cost
Define normothermia.
Hypothermia=
Hyperthermia=
37 deg C
<36 deg C
> 38 deg C
What regulated body temperature?
hypothalamus
Causes of hypothermia.
Body’s response=
low ambient OR temperature radiation evaporation convection conduction Body's Response = vasoconstriction & shivering
List risk factors contributing to hypothermia.
high ASA lengthy or involved surgery combined epidural/general anesthsia long surgery elderly lean body mass
Protective factors against hypothermia? (3)
Increased body weight
Higher preop temp
Warmer rooms
Causes of hyperthermia.
Body’s response =
malignant hyperthermia fever infection hypermetabolic state amphetamines, cocaine, ecstasy atropine- inhibit sweating Body response = vasodilation &sweating
When does the greatest heat loss occur perioperatively?
first hour
Define radiant heat loss.
transfer of body heat into a cooler environment
What accounts for the majority of heat loss perioperatively?
Second most cause?
1st=radiant heat loss
2nd= evaporative
Define evaporative heat loss.
liquids on the skin dissapating into the air.
cleasing and perspiration
Define convection heat loss.
through moving cool air
Define conductive heat loss.
through direct contact with a cooler object
Define redistribution heat loss.
Lower temperature blood from vasodilated periphery to central compartment
What types of anesthesia inhibit thermoregulation & cause significant vasodilation?
general and regional
What is the ASA’s position on temperature monitoring?
when significant changes in temperature are intended, anticipated, or suspected
What is the AANA’s position on temperature monitoring?
all pediatric patients receiving general anestesia and when indicated in all other patients
Types of core temp monitoring ? Which are most accurate?
Core temp is most reflective of _____
Types: tympanic membrane, distal esophagus, nasopharynx, pulmonary artery
Most accurate: IV (pulm artery) or Bladder Thermistor
Core Temp is most reflective of thermal state
Out of OR increased anesthetic risks caused by: (3)
- Decreased anesthesia staff available
- Less adjunct equipment
- Unfamiliarity with support staff & settings
What is the most common mechanism of injury for anesthesia adminisered outside the operating room?
inadequate oxygenation or ventilation
Pressure-volume loops provide insight into lung _________ and show volume on the ______ axis
Compliance, vertical
Flow-volume loops provide information on pulmonary ______. And volume is on the _____ axis
Resistance, horizontal
