Section 3: General Principles of Anesthesia Flashcards
Define “MET:’
A MET is a Metabolic EquivalenT and is defined as the amount of oxygen
consumed while sitting at rest
MET are used to
evaluate functional capacity
and reserve.
1 MET equal
equal to 3.5 mL 02/kg/min
Metabolic equivalents (METs) range from
1 to I2 (in whole numbers).
MET for eating, working at a computer, or dressing.
One metabolic equivalent ( 1 MET) correlates
METs: walking down stairs, walking in your house, or cooking.
2 METS
MET for walking one or two blocks on level ground.
3 METs correlates
MET: Raking leaves or gardening is equivalent to
4 METs.
METs for climbing one flight of stairs, bicycling or dancing. Six metabolic equivalents ( 6 METs) is .
Five metabolic equivalents (5 METs}
METS playing golf or carrying golf clubs
6 METs
Playing singles tennis.
7 METs correlates to
Rapidly climbing stairs or slowly jogging is equivalent to
8 METS
Correlates with jumping rope slowly or
moderate cycling.
Nine metabolic equivalents (9 METs
Swimming quickly, running or jogging briskly.
10 METs
Cross country skiing or playing full court basketball.
11 METs
Running rapidly for moderate to long distances is equivalent to
12 METs
Define the physical status index "ASA PS class 6."
Declared brain-dead patient whose organs are being removed for donor purposes is defined as ASA PS class 6
How much dextrose is in a 1-liter bag of
DSW? What is the dextrose concentration
{mg/mL)?
A one-liter (I L) bag of DSW contains 50 grams of dextrose, a concentration
of 50 mg/ml
In addition to sodium {140 mEq/L) and
potassium (5 mEq/L), what three electrolytes does Normosol-R contain?
In addition to physiologic concentrations of sodium and potassium, Normosol-R contains magnesium (3 mEq/L), acetate (27 mEq/L) andgluconate (23 mEq/L).
List 4 reasons why dextrans are of limited
use nowadays.
Dextran toxicities include:
(I) Antithrombotic effects, particularly inhibition of platelet aggregation;
(2) interference with blood cross-matching-dextrans coat RBC membranes;
(3) anaphylactic and anaphylactoid reactions; and
(4) renal dysfunction resulting from osmotic nephrosis.
Dextrans are relatively ___but what limits their use?
inexpensive (dextrans are produced by bacteria), but their range of toxicities limits their use.
Which blood components are found in
packed red blood cells (PRBC)?
Packed red blood cells (PRBC) contains red blood cells in anticoagulated
plasma.
In PRBCs, Most plasma is removed
(by centrifugation) and is replaced by pre·
servative, most commonly citrate phosphate dextrose adenine-I (CPDA-1).
The addition of adenine to packed red blood cells (PRBC) stored in CPD
extends the storage time from 21 days to ____days.
The addition of adenine to citrate phosphate dextrose (CPD) solution
allows RBCs to resynthesize adenosine triphosphate (ATP}, which extends
the storage time from 21 to 35 days.
How long can RBCs or WHOLE blood can be stored _______when stored in ___
As a result, RBCs or whole blood can
be stored for 35 days when stored in CPDA-1.
Name three preservatives that extend the storage time of packed red blood cells (PRBC) from 3S days to 42 days.
The shelf life of packed red blood cells {PRBC) can be extended to 42 days when AS- I (Adsol). AS-3 (Nutricel), or AS-S (Optisol) is used
Extending blood storage to 42 days is a mixed blessing. Describe the bio-chemical alterations of stored blood.
During storage, RBCs metabolize glucose to lactate, hydrogen ions mutate, and plasma pH decreases. The storage temperatures of 1 °C to 6 °C depress the sodium-potassium pump, thus RBCs lose K+ and gain Na+. Some RBCs undergo lysis, resulting in increased plasma Hb levels. Progressive decreases in ATP and 2,3-diphosphoglycerate (2,3-DPG) occurduring storage and factors V and VII (most labile factors) are decreased as
well. Summary of plasma changes in stored blood: fewer RBCs in an acidic,
hyponatremic, hyperkalemic, hypoglycemic plasma, with increased free hemoglobin and decreased 2,3-DPG.
Which blood components are present in frozen plasma (FFP)?
Fresh-frozen plasma contains ALL clotting factors, naturally occurring inhibitors of coagulation, and antithrombin (formerly antithrombin III). FFP is devoid of red blood cells and platelets
Which blood components are present in cryoprecipitate?
Cryoprecipitate is a protein fraction collected from the top of thawing FFP and therefore contains concentrated factors I, VIII, vWF, XIII, and fibronectin
Which blood product contains the greatest concentration of fibrinogen (factor I)?
Cryoprecipitate contains more fibrinogen per volume than fresh-frozen plasma, specifically l S g/L in cryo compared to 2.S g/L in FFP ( 6x more fibrinogen in cryo).
State the threshold for fibrinogen replacement
The traditional threshold for fibrinogen replacement is fibrinogen levels less than 80 to 100 mg/dL.
How many bags of cryoprecipitate constitute a single dose?
A single dose- 5 pooled bags of cryoprecipitate
What is the expected fibrinogen increase following one dose of cryoprecipitate
typically raises the fibrinogen concentration by 5O mg/dL
UPTDATE THIS: According the the AS/\s 2006 updated practice guidelines, at what hemoglobin level is RBC transfusion rarely indicated?
rarely indicated when the Hgb concentration is more than 10g/dL
At what Hgb level is RBC transfusion always indicated?
Almost always indicated when is less than 6g/dL , especially when anemia is acute
According to the ASA 2006 updated practice guidelines, what factor justifies RBC transfusion when hemoglobin levels are intermediate (6- 10 mg/dL)?
should be based on the patients risk for complications of inadequate oxygenation.
List four (4) variations of head-elevated surgical positions.
Four variations of head-elevated positions are: (l) sitting, including lounge
chair and beach chair variation; (2) supine- tilted head up; (3) lateral-tilted
head up, also called the .. park bench” position; and, (4) prone- tilted
head up.
Is the most feared complication of head up surgical positions, as you know.
Venous air embolism
In head up positions may compromise the airway.
Edema of the face, neck, and tongue
What is the cause of edema in these areas in a head up position?
Edema of the face, neck, and tongue in head up positions, including severe
postoperative macroglossia, is purportedly due to venous and lymphatic obstruction caused by prolonged, marked neck flexion.
What precautions should be taken to
minimize the occurrence of face, neck,
and tongue edema in the head up
positions?
Avoid placing the patients chin against the chest- do not force the chin into the suprasternal notch- and use an oral airway to protect the endotracheal tube.
What nerve injury may occur from a
sternal retractor?
Spreading of the sternal retractor during cardiac surgery causes the clavicle
to move posteriorly and the first rib to move upward thus pinching the brachial
plexus between the two bones.
Dissection of the internal mammary artery requires wide, asymmetric chest retraction and may lead to
brachial plexus neuropathy,
Brachial plexus injury from sternal rectractor most often manifest as
sensory deficit in the distribution of the ulnar nerve
Describe the method and rationale for
denitrogenation (pre-oxygenation) of
the airway.
With a tight mask seal, provide 100% oxygen at a flow rate high enough
to prevent rebreathing ( 10-12 L/min). Slight head up position has been
recommended. Denitrogenation allows the patient’s functional residual capacity (FRC) to be filled with approximately 90% oxygen, thus lengthening the apnea time without desaturation and improving safety.
How is an oropharyngeal airway sized?
Measure from the corner of a patient’s mouth to the angle of the jaw or earlobe.
What problems may be seen with their
usage?
Poorly sized oral airway devices can actually worsen the obstruction. Other complications include lingual nerve palsy and damage to teeth.
Name 4 types of supraglottic airways.
Laryngeal mask airways (i.e. LMA classic, LMS ProSeal, LMA Supreme),
Perilaryngeal sealers (air-Q SP),
Cuffless preshaped sealers (i-gel), and •
Cuffed pharyngeal sealers
Describe the advantages of supraglottic airways.
Advantages include the ease and speed of placement, reduced anesthetic requirements and the resulting hemodynamic stability, less airway manipulation, less dental trauma, less coughing on emergence, and less risk of bronchospasm.
Describe the disadvantages of supraglottic airways.
Ineffective ventilation when higher airway pressures are required, no protection from laryngospasm, and no protection from gastric aspiration, though newer models of SGA devices have been designed to reduce this risk.
Describe the benefits of alternative LMs,
including the i-gel and air-Q.
The i-gel is a cuffless LM. Its advantages include a simplified insertion and easy positioning. The air-Q device has a self-pressurized cuff that eliminates overinflation. Both alternative supraglottic devices reduce the incidence of sore throat.
What is the Fasttrach LMA?
The Fastrach LMA, or intubating LMA (ILMA), was specifically designed
for use in difficult airway situations.
The primary distinguishing features of
the Fastrach LMA are:
[1} an anatomically curved rigid airway tube;
(2} anintegrated guiding handle;
(3} an epiglottic elevating bar; and,
(4} a guiding ramp built into the floor of the mask aperture
What advantage does the epiglottic
elevating bar afford the ILMA (Fastrach
LMA)
The 2 bars at the aperture of the LMA classic are replaced in the ILMA by
a single, moveable epiglottic elevating bar that pushes the epiglottis out of the way allowing smooth and unobstructed passage of the endotracheal
tube as it emerges from the distal end of the ILMA’s metal shaft.
What are the advantages of the integrated guiding handle on the Fastrach LMA
{ILMA)?
The integrated handle at the proximal end of the barrel of a Fastrach LMA
is used for insertion, repositioning, and removal. The position of the device
can be optimized by lateral and anterior-posterior manipulation by using
the integrated handle, an action called the Chandy maneuver
What is the “RODS” mnemonic?
"RODS" is used to identify difficult extraglottic device situation. Restricted mouth opening Obstruction Distorted airway or disrupted airway Stiff lung or stiff cervical spine
What is the most common adverse effect
reported with the use of the laryngeal
mask airway (LMA)?
Sore throat with an incidence of 10% is the most common adverse effect of
using an LMA.
The sore throat with LMA is most often related to
over inflation of the cuff.
You decide a laryngeal mask airway (LMA) is appropriate for the airway management of the 9-kg patient, but a 1.5 LMA is not available; will you use a size l or a size 2 LMA?
LMA size selection is critical to its successful use, and to the avoidance of minor as well as more significant complications. The manufacturer recommends that the clinician choose the largestsize that will fit comfortably in the oral cavity, and then inflate to the minimum pressure that allows ventilation to 20 cm H10 without an air leak. Accordingly, a size 2 LMA classic is appropriate for the 9-kg patient
Pediatric LMA sizing is based on
weight.
What are the approximate weights for LMA sizes 1 through 3? < 5 Kg
Size 1
What are the approximate weights for LMA sizes 1 through 3? Weight 10-20
Size 2
What are the approximate weights for LMA sizes 1 through 3?Weight 5-10 kg
Size 1.5
What are the approximate weights for LMA sizes 1 through 3? Weight 20-30 kg
Size 2.5
What are the approximate weights for LMA sizes 1 through 3? Weight 30-50
Size 3
List indications for using an Esophageal-
Tracheal Combitube {ETC).
Indications for an ETC include supraglottic obstruction, morbid obesity, vomiting, regurgitation, massive airway or upper gastrointestinal bleeding, and acute bronchospasm.
The ETC requires
minimal training for proper placement.
Airway reflexes should not be intact during
ETC use.
Describe the functions of the Air-Q
perilaryngeal tube?
The Air-Q is an SGA device. It acts as a conduit for blind, or more likely,
fiberoptic placement of an ETT.
How is the King LT positioned for proper
ventilation
When properly placed, the esophageal cuff is seated in the esophagus, with the opening positioned over the larynx. Both cuffs are then inflated simultaneously by injecting air in just one inflation port. This will provide a sealed method for ventilation.
The King laryngeal tube has a
small esophageal cuff and a larger hypopharyngeal cuff, with an opening between the 2 cuffs
With the king LT If ventilation is inadequate, the device is
likely inserted too deep
Describe removal of a supraglottic
device.
Properly timing the removal of an SGA is critical. The patient should either be deeply anesthetized, or awake enough to open mouth on command. Removing
the device during the excitation phase of emergence can result in Iaryngospasm. The cuff remains inflated to lessen the amount of secretions left behind and dropping into the airway.
