1
Q
Supine Position Complications
A
* Backache (worse if over 3 hours, normal lumbar curvature is lost from lack of paraspinous muscle tone
* Pressure allopecia
* Brachial Plexus Injury or Axillary nerve injury if arms abducted over 90 degrees
* Ulnar nerve injury if hand arm is pronated down
* stretch injury when neck is extended and head turned away
2
Q
Trendelenburg Pathophysiologic Considerations
A
- Increased CO (from Inc VR from LE)
- ** increased ICP and IOP, possible Vision loss**
- Edema of face, conjunctiva, larynx, tongue (worse with longer surgery and fluid overload)
- increased intraabdominal pressure
- Decreased FRC and pulmonary compliance (diaphram shifts cephalad
- Higher pressures may be needed to vent well
- Enodbronchial intubation risk as carina also shifts cephalad
3
Q
Beach Chair Position Risk
A
- Zero a-line at the tragus- cerebral hypoperfusion risk/air emboli
- pnemoceph-air in sudural/ventricles putting pressure on surrounding structures
- Quadriplegia and spinal cord infarct-c-spine overextension
- cerebral ischemia-c-spine overextension
- Peripherial Nerve injury- Sciatic most often
4
Q
Prone Position Risks
A
- Facial/airway edema
- Nerve injuries: Ulnar if elbows not padded, brachial plexus is arms abdudcted over 90 degrees
- POST OP VISUAL LOSS FROM ISCHEMIA/HYPOPERFUSION
- Eye injuries from head position
- ETT dislodgement
- loss of monitors/IV
5
Q
Lithotomy Position and Considerations
A
- Patient laying supine with legs up in padded or “candy cane” stirrups
- Arms tucked or on arm boards
If using Trendelenburg or reverse Trendelenburg, need non-sliding mattress - Hips flexed 80 -100 degrees and legs abducted 30 - 45 degrees from midline, knees flexed
- Lower extremities MUST be raised and lowered in synchrony together-prevents lower spine injury
- Foot of the bed is lowered, must protect the hands and fingers from crush injury-MITTENS
- Surgery > 2-3 hours, periodically lower the legs
6
Q
Lithotomy Risk
A
- Back pain
- Nerve injuries
- Brachial plexus
- Ulnar nerve injury
- Common peroneal injury- common from leg supports
- Lateral femoral cutaneous injury-KEEP LEGS FROM BEING FLEXED 90DEGREES OR MORE AT HIP TO PREVENT INGUINAL STRAIN
- Compartment syndrome-OCCLUSION OF LOWER EXTREMITY VENOUS PLEXUS
7
Q
Lateral Decubitus Positioning
A
- If bed flexed or kidney rest used, needs to be placed under iliac crest
- Inferior vena cava compression can occur
- Allowing best possible expansion of the dependent lung
- Nerve injuries
- Ulnar nerve injury if elbows are not padded
- Brachial plexus injury if arms are abducted > 90 degrees
- ETT dislodgement(with patient turns); caution with use of LMA
8
Q
A patient is supine with the neck extended and the head turned to the right, away from the surgical site. Which positioning complication may occur?
A
Stretch injury (brachial plexus)
9
Q
Where does HCO3- enter and leave
A
Kidneys at the proximal tubule
10
Q
Where does H+ enter and leave the body
A
Distal Tubule and collecting duct
11
Q
If PaCO2 and HCO3- are changing in the same direction what kind of issue is it
A
Primary Disorder with secondary compensation
12
Q
PaCO2 and HCO3- are changing in the OPPOSITE directions what type of issue is it
A
Mixed Acid/Base disorder
13
Q
Acidosis Cardiac consequences
A
- pH 7.2-Decreased contractility/MAP
- sensitive to dysrhythmia
- lower threshold for VF
- pH 7.1 dec responsiveness to catecholamines
14
Q
Respiratory Acidosis bicarb compensation
A
Acute Hypercarbia- per 10mmHg of PaCO2 increase, plasma HCO3- increases 1 mmol/L
Chronic hypercarbia- per 10 mmHg of PaCO2 increase, HCO3- increases 3 mmol/L
15
Q
Respiratory Acidosis Intervention and concern with chronic hypercarbia
A
Mechanical ventilation If hypercarbia marked and CO2 narcosis present
Caution with chronic hypercarbia reversal….excessive bicarb causes CNS irritability…seizure
16
Q
Acute metabolic acidosis expected PaCO2 shift
Formula and rating of compensation card
A
- “Lowered blood pH indicating problem:
- Respiratory compromise doesnt counter acid production
- Caused by: increased acid production, decreased excretion
- You ingest something ridiculous or Renal/GI system cant hold on to bicarb
- (1.5 x HCO3- + 8)
If 1 mEq/L decrease in base excess- PaCO2 should decrease 1.2 mmHg-if not compensation is indequate
17
Q
Simple Anion Gap formula
A
Na - (Cl- + HCO3-) = 12-14 mEq/L ish
18
Q
Conventional anion gap
A
(Na+ + K+) - (Cl- + HCO3-) = 14-18 mEq/L
both simple and conventional underestimate disturbance-hypoalbuminemia and hypophosphatemia are a thing
19
Q
Bicarb Correction formula, tissue effect interplay in situ, and how to admin
A
reacts w/ H+ → generates CO2 →dec pH further
-in chronic metabolic acidosis, acute pH changes negates right shift (Bohr effect is countered) → tissue hypoxia
-bicarb correction dose = 0.3 x base deficit x kg (give ½ dose and reassess)
20
Q
Respiratory Alkalosis Causes
A
- High altitude
- PREGNANCY
- Salicylate Poisioning (Aspirin)
- Iatrogenic Hyperventilation (spooked about surgery-then hyperventilates)
21
Q
Respiratory Alkalosis symptoms and Ion consideration
A
Lightheadedness, Vision issues, and dizziness from low PaCO2
* GREATER BINDING OF CA++ TO ALBUMIN
* Leads to hypocalcemia and thus cramps, spasms, circumoral numbness and seizures
* Trousseau’s and Chvostek’s signs
22
Q
Metabolic Alkalosis causes
A
- DIURETIC THERAPY
- Hyperaldosteronism
- NG Suction
- Hypovolemia
- Vomitting
give Spironolactone (K sparing → H+ sparing)
give carbonic anhydrase inhibitor (Acetazolamide) to renally excrete bicarb
23
Q
Definition of a breathing system
A
- delivers gas to patient
- removes CO2
- provides heating/humidification of gas mixture
- allows spontaneous, assisted, or controlled respiration/ventilation
- provides gas sampling, measures airway pressure, monitors volume
24
Q
Open Circuit Classification
A
NO RESERVOIR BAG, NO REBREATHING
Open to atmosphere, think nasal cannula
25
Semi-open breathing system
Resevoir bag ***no rebreathing***
Mapleson circuit, or a vent with FGF greater than MV
26
Semi-closed
Resevoir bag, and *partial* rebreathing
Partial rebreathing occurs but some waste flow is vented through APL or waste gas valve of ventilator
e.g. low-flow anesthesia
FGF is LESS than minute ventilation
50% of expired gas is rebreathed after CO2 removal
27
Inspiratory Valve
Prevents backflow of gas
gotta be hydrophobic
28
29
Expiratory Valve
Prevents rebreathing
hydrophobic
Must be between patient and resevoir bag
30
Apparatus Deadspace
**From Y-piece to patient
if inspiratory valve is stuck that arm is now apparatus deadspace also**
31
Breathing/Resevoir Bag Specs
**ELLIPSOIDAL for 1 hand operation**
3L for adults (0.5-6L)
must have **22mm female connector on neck**
min pressure **30 cmH2O, 40-60cmH20 max** (rubber bags)
plastic has 2x distending pressure vs rubber
32
Resevoir Bag Function
Resevoir for O2/Volatiles
manual vent or assisting with spontaneous venting
Tactile/visuall indicator of ventilation
protects against excessive positive pressure
**Visual monitor of ventilation/accumulation of gases within circuit**
33
APL Valve
Adjustable Pressure limiting valve/ Pop-off Valve
controls pressure in system
**CLOCKWISE CLOSES APL, INCREASING SYSTEM PRESSURE (PEEP)**
CCWOpposite motion, decreases pressure
1-2 clockwise turns from fully open to fully closed
An arrow must indicate direction to close valve
34
Absorbant Indicators function and colors
Ethyl violet is the most common dye
Ethyl orange, cresyl yellow
**Color change is from Carbonate formation**
pH becomes less alkaline
White to blue violet
Undergoes color change around pH of 10.3
Fresh absorbent is colorless, pH > 10.3
Exhausted absorbent is purple, pH < 10.3
Bleaching-fluorescent light deactivates dye
depend on capnography as color abosrption could be altered
35
Channeling, and methods of prevention
Small passage ways allowing gas to flow through low-resistance areas
-Decreases functional absorptive capacity
Minimized by
**Circular baffles(round circular tube in absorbent)**
Placement for vertical flow
Permanent mounting
Prepackaged cylinders
Avoiding overly tight packing-can lead to channeling
36
Carbon Monoxide formation
Dry absorbent/Dessicated
more likely if FGF inlet is close to CO2 abosrber, or leaving FGF on
Carboxyhemoglobin levels can reach 35% in patient
Pulse ox or IR gas monitors will not detect it
’Monday, 1st case’
Highest levels **Desflurane ≥ enflurane > isoflurane > halothane > sevoflurane**
Increased temperatures
Increased concentrations of anesthetic gases
Low FGF rates
Strong base absorbents (KOH or NaOH)
37
Mapleson Circuits do have and do not have what
Reservoir bag
Corrugated tubing
APL valve
Fresh gas inlet
Patient connection (Maple E doesnt have Bag or APL
**NO CO2 absorber**
NO UNIDIRECTIONAL VALVES
NO SEPARATE INSPIRATORY OR EXPIRATORY LIMBS (except bain)
38
Mapleson efficency for SV and Controlled ventilation
Mapleson A is best for SV (DEF, then BC)
Mapleson D(E or F) is best for controlled, (BC, then A)
39
Humidify Definition
**Amount of water vapor in a gas**
40
Absolute Humidity
**Mass of water vapor in gas (mg H2O/L of gas)**
41
Relative Humidity
% Saturation, amount of water vapor at a given temp
42
Under humidification issues
* Damage to respiratory tract
* Secretions thicken
* Ciliary function decreases
* Surfactant activity is impaired
* **Mucosa susceptible to injury**
* Body heat loss-neonates and children
* Tracheal tube obstruction
* Increases resistance and work of breathing from thickened secretions
43
Over humidification issues
* Condensation of water in the airway
* Reduced mucosal viscosity and risk of water intoxication
* Inefficient mucociliary transport
* Airway resistance, risk of pulmonary infection, surfactant dilution, atelectasis, and V/Q mismatch
* Obstruction to sensors
44
HME (Heat and Moisture Exchanger) Function, location, and affect on deadspace
* Conserves some exhaled heat and water and returns them to the pt
* Bacterial/viral filtration and prevention of inhalation of small particles (HMEF)
* Disposable with exchange medium enclosed in plastic housing
* **Placed close to the pt, between Y piece and proximal end of ETT or LMA**
* increased deadspace (apparatus)
45
Humidifier use, location, special population considerations, and forms
* **Neonates**, pts with difficult respiratory secretions, or hypothermic pts see use often
* Passes a stream of gas in various ways: Bubble or cascade, Pass-over
Counter-flow, Inline
* May be heated or unheated
* Placed in inspiratory limb downstream of unidirectional valve
* Heated humidifiers should not be placed in expiratory limb
* Condensation can decrease delivered Vt
* Water traps - change frequently to decrease risk of contamination and infection
46
OPAs
**Lifts tongue and epiglottis away from posterior pharyngeal wall**
**Decreases work of breathing during SV (when used with face mask)**
**Size by measuring corner of mouth to angle of jaw/earlobe**
47
NPA use, C/Is, Proper seating
-use to dilate nasal passage prior to nasal intubation
-tolerated in pts w/ intact airway reflexes (awake)
-used when loose teeth, oral trauma, gingivitis, limited mouth opening
C/I in basilar skull fx, nasal deformity, hx epistaxis, pregnancy, coagulopathy
Design: shortened tracheal tube
-flange at outer end to prevent complete passage
-less stimulating than OPA (better tolerated)
-sized by outer diameter in French scale
Insertion: sized bony mandible or nostril to external auditory meatus (earhole)
** -bevel of NPA rests above epiglottis**
-insert parallel to inferior nasal floor
48
LMA Classic shape, location when in use and materials
Shaped like a TT proximally
Elliptical mask distally
**Sits in hypopharynx and surrounds the supraglottic structure**
An inflatable cuff
Latex free, reusable, disposable
49
LMA Insertion
Well lubed
hold like a pencil
press upward against hard palate
follow posterior pharyngeal wall, pressing backward in a smooth motion
*should feel it curve around and downward in airway, advance until resistance felt*
**When balloon inflated, neck bulged and LMA may "rise" slightly indicating it is seated**
50
LMA Advantages
**Ease of insertion**
quick to place
improved hemodynamic stability(not as stimulating with induction drugs)
reduced anesthetic requirements
no paralytics needed
avoids some ETT risk such as trauma/bronchospams
51
Mac Blade Points
Tongue has gentle curve
**#3 and #4 useful for adults**
**Has been shown to cause greater cervical spine movement than with Miller**
Makes intubation easier because blade requires adequate mouth opening due to blade size
52
Miller Blade Points
Miller blades
Tongue is straight with slight upward tip
**#2 and #3 for adults**
less Force, less head extension, and cervical spine movement
Great for smaller mouths and longer necks
**LIfts epiglottis**
53
Miller Blade view
**Blade lifts epiglottis**
If blade inserted too far, it elevates larynx or esophagus
If withdrawn too far, epiglottis flips down and covers glottis
Can use like a Macintosh to insert into the vallecula
54
Rigid Indirect Laryngoscopes
Stainless steel, lighted stylet with malleable distal tip; design utilizes eye piece
**Oxygen port for oxygen insufflation**
Neutral position, inserted midline; available in adult and peds sizes
Stylet advanced into trachea; **light pressure and tip anterior at all times to avoid injury**
Can be used as a light wand, check ETT placement, or placement of double-lumen ETT
55
Optical Stylet Pros
**Easy to use for routine and difficult intubations(ala fiber optic scopes)**
Trachea is visualized, esophageal intubation should not occur
Decreased incidence of sore throat
Results in less c-spine movement over conventional laryngoscopy
56
Optical Stylet Cons
Longer intubation time
Cannot be used with nasal intubation
Cannot be adjusted into a precise direction compared to a traditional malleable stylet
57
Video laryngoscope pros
Magnified anatomy
Some scopes have curved/straight blades to mimic laryngoscopes
Operator and assistant can see
May result in decreased c-spine movement
Further distance from infectious patients
Demonstrates correct technique in legal cases
58
Video laryngoscope cons
Requires video system
Portability varies
**Strongest predictors of failure: altered neck anatomy with presence of a surgical scar, radiation changes, or mass**
59
Laryngoscopy Complications
**Dental injury Most frequent anesthesia-related claim**
Most likely damaged teeth, Upper incisors (9, 10, 8) and left more likely than right
Restored or weakened teeth
Tooth protectors
Placed on upper teeth during DL
Protects from the blade causing direct surface damage
Does not guarantee safety from dental trauma
60
ETT Design
Internal and external walls circular
Decreases kinking
Can be shortened at machine end
**Patient end has slanted bevel**
Helps view larynx
Murphy eye
Provides an alternate pathway for gas flow
61
Laser-Resistant ETT
Metallic or silicone and metal mixture
Reflects laser beams-CO2 or KTP laser
Cuffs contain methylene blue crystals
Saline-*Not laser resistant*
Double cuffs-Fill with methylene blue saline solution to detect laser biffs
**Distal cuff first, then proximal cuff **
62
ETT Markings
**On bevel side above the cuff**
**Read from pt side to machine side**
Safety standards
The word oral or nasal or oral/nasal
Tube size in ID in mm
Name of manufacturer
**Graduated markings in centimeters from patient end**
Cautionary note… single use only if disposable
**Radiopaque marker at patient end**
62
ETT Cuffs
Inflatable balloon near patient end of tube
Strong, tear-resistant, thin, soft, and pliable
Must not herniate over murphy eye or bevel of tube
**wCuff pressure = 18 - 25 mm Hg; usually 8 - 10 mL of air**
Monitor cuff pressure frequently if using nitrous as this causes cuff inflation/expansion
63
ETT Complications
Vocal cord granuloma (mass that results from irritation
Common in adults; females
Trauma, ETT too large, infection, and excessive cuff pressure
S/S: **Persistent hoarseness, fullness, chronic cough, intermittent loss of voice**
Treatment: laryngeal evaluation, voice rest
64
Airway Bougie
Polyester base with resin coating
Distal end angled 30-45 degrees
Introduced with anterior positioning of the tip
**Blind intubation if glottic exposure is absent**
ETT passage is difficult
Advance gently
**Feel clicking sensation across tracheal rings**
65
Right Mainstem Points
Shorter, straighter, **larger diameter
25 degree takeoff from trachea**
RUL tracheal takeoff very close to origin
Avg length 2.5 cm from carina to take-off
66
Left Mainstem Points
45 degree takeoff from trachea
LUL tracheal takeoff more distal
Avg length 5.5 cm from carina to take-off
67
Double Lumen Tube Insertion
*-left DLT primarily used (to avoid blocking RUL bronchus)
-right DLT for left lung surgeries (eg: transplant)*
Insertion:
Placed similarly as a standard ETT-more difficult due to stiffness and size
Advance through the larynx with angled tip anterior into the trachea
Bronchial cuff passes the cords, the tube is turned 90 degrees
Bronchial portion points toward the appropriate bronchus
Verification of the location of the bronchial port with an fiberoptic scope
**Blue bronchial cuff is just below the carina in the appropriate bronchus**
Inflate bronchial balloon under direct visualization to verify proper placement
Ensure bronchial cuff does not herniate over the carina
Isolate a lung by clamping either the tracheal or bronchial connector
68
Indications For Bronchial-Blockers
When DLT is not advisable, *can block a segment of lung without isolating the whole thing*
Nasal intubation
Difficult intubation
**Patients with tracheostomy**
Subglottic stenosis
Need for continued postoperative intubation
If a single-lumen tube is already in place
Critically ill pts
69
Resistance of ETT is determined by whut
Length, and internal diameter of tube (config and connectors)
*Jean Poiseuille has entered the chat*
Clinical Reference Deck
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