Unit 1: Respiratory Flashcards
1
Q
Which muscles tense and relax the vocal cords?
A
CricoThyroid: “Cords Tense”
ThyroaRytenoid: “They Relax”
2
Q
What muscles abduct and adduct the vocal cords?
A
Posterior CricoArytenoid: “Please Come Apart”
Lateral CricoArytenoid: “Let’s Close Airway”
3
Q
Describe the sensory innervation of the upper airway
A
Trigeminal: V1 (nares, anterioer 1/3 of septum); V2 (turbinates, septum); V3 (anterior 2/3 of tongue)
Glossopharyngeal: posterior 1/3 of tongue, soft palate, oropharynx, vallecula, anterior side of epiglottis
Superior Laryngeal: Internal branch (posterior side of epiglottis to level of vocal cords); External branch (no sensory)
Recurrent Laryngeal: below vocal cords to trachea
4
Q
How does recurrent laryngeal nerve injury affect the integrity of the airway?
A
Bilateral Injury:
- acute – respiratory distress (unopposed action of cricothyroid muscles)
- chronic – no respiratory distress
Unilateral: no respiratory distress
5
Q
How does superior laryngeal nerve injury affect the integrity of the airway?
A
Bilateral: hoarseness and no respiratory distress
Unilateral: no respiratory distress
6
Q
What are the 3 airway blocks? Identify the key landmarks for each one.
A
Glossopharyngeal Nerve Block: palatoglossal arch at the anterior tonsillar pillar
Superior Laryngeal Nerve Block: greater cornu of hyoid
Transtracheal Nerve Block: circothyroid membrane
7
Q
What are the 3 paired and 3 unpaired cartilages of the larynx?
A
Unpaired: epiglottis, thyroid, cricoid
Paired: corniculate, arytenoid, cuneiform
8
Q
What is the treatment for laryngospasm?
A
- 100% FiO2
- Remove noxious stimulation
- Deepen anesthesia
- CPAP 15-20
- Open the airway (head extension, chin lift)
- Larson’s maneuver
- SUX
9
Q
How to the respiratory muscles function during the breathing cycle?
A
Contraction of inspiratory muscles reduces thoracic pressure and increases thoracic volume — example of Boyle’s Law
Inspiration: diaphragm increases superior/inferior dimension – external intercostals increase AP diameter – accessory muscles are sternocleidomastoid and scalene muscles
Exhalation: usually passive - driven by recoil of chest wall – abd musculature assist in active exhalation
10
Q
What is the difference between Minute Ventilation and Alveolar Ventilation?
A
Minute Ventilation (Ve): amount of air in a single breath multiplied by number of breaths per minute — Ve = Vt x RR
Alveolar Ventilation (VA): only measures the fraction of Ve that is available for gas exchange (removes anatomic dead space from minute ventilation equation) — VA = (Vt - Anatomic dead space) x RR
- directly proportional to CO2 production
- indirectly proportional to PaCO2
11
Q
What are the four types of dead space?
A
Anatomic Vd – air confined to the conducting airway (nose/mouth to terminal bronchioles)
Alveolar Vd – alveoli that are ventilated but not perfused (reduced pulmonary blood flow - decreased CO)
Physiologic Vd – anatomic Vd + alveolar Vd (anything that increases anatomic or alveolar Vd)
Apparatus Vd – Vd added by equipment (facemask, HME, limb of circle system if incompetent valve present)
12
Q
What does the alveolar compliance curve tell you?
A
Alveolar ventilation is a function of alveolar size and its position on the alveolar compliance curve
- best ventilated alveoli are the most compliant (steep slope of the curve)
- poorest ventilated alveoli are the least compliant (flat portion of the curve)
13
Q
What does the V/Q ratio represent?
A
V/Q ratio = ratio of ventilation to perfusion (minute ventilation / CO)
- normal Mv = 4 L/min
- normal CO = 5 L/min
- normal V/Q ratio = 0.8
14
Q
What are the different V/Q mismatch scenarios?
A
If V/Q ratio >0.8 – moves toward dead space
If V/Q ratio <0.8 – moves toward shunt
-dead space = V/Q of infinity
shunt = V/Q of 0
15
Q
What are the West zones of the lung?
A
Zone 1: PA > Pa > Pv — dead space - ventilation w/o perfusion
Zone 2: Pa > PA > Pv — waterfall - normal physiology
Zone 3: Pa > Pv > PA — shunt - perfusion w/o ventilation
Zone 4: Pa > Pist > Pv > PA — pressure in the interstitial space impairs ventilation and perfusion
16
Q
What is the alveolar gas equation?
A
Alveolar Oxygen = FiO2 x (Pb - PH2O) - (PaCO2/RQ)
Pb = atmospheric pressure PH2O = 47 mmHg RQ = 0.8 (respiratory quotient)
- tells us that hypoventilation can cause hypercarbia and hypoxemia – also explains how supplemental O2 reverses hypoxemia, but does nothing to reverse hypercarbia
- Alveolar oxygen in healthy pt breathing room air at sea level ~105.98 mmHg
17
Q
What is the A-a gradient? What factors affect it?
A
The difference between alveolar oxygen (PAO2) and arterial oxygen (PaO2)
- helps diagnose the cause of hypoxemia by quantifying the amount of venous admixture
- it is less than 15 mmHg
Increased by high FiO2, aging, vasodilators, right to left shunting, and diffusion limitation
18
Q
What are the five causes of hypoxemia? Which ones do supplemental O2 reverse?
A
- Reduced FiO2 (normal A-a gradient) — Yes
- Hypoventilation (normal A-a gradient) — Yes
- Diffusion Limitation (increased A-a gradient) — Yes
- V/Q Mismatch (increased A-a) — Yes
- Shunt (increased A-a) — No, no way for O2 to access the pulmonary capillary
19
Q
What are the five lung volumes? What are the reference values for each?
A
Inspiratory Reserve Volume - 3000 mL (volume of gas that can be forcibly inhaled after a tidal inhalation)
Tidal Volume - 500 mL (volume of gas that enters and exits the lungs during tidal breathing)
Expiratory Reserve Volume - 1100 mL (volume of gas that can be forcibly exhaled after a tidal exhalation)
Residual Volume - 1200 mL (volume of gas that remains in the lungs after a complete exhalation)
Closing Volume - ~30% age 20 ~55% age 70 (volume above residual volume where the small airways begin to close)
20
Q
What are the five lung capacities? What are the reference values for each?
A
- Total Lung Capacity - 5800 mL (IRV+TV+ERV+RV)
- Vital Capacity - 4500 mL (IRV+TV+ERV)
- Inspiratory Capacity - 3500 mL (IRV+TV)
- Functional Residual Capacity - 2300 mL (RV+ERV) – lung volume at end expiration
- Closing Capacity - variable (RV+CV) – absolute volume of gas contained in the lungs when the small airways close
21
Q
What factors influence functional residual capacity (FRC)?
A
Conditions that Reduce – tend to reduce outward lung expansion and/or reduce lung compliance
- when FRC is reduced, intrapulmonary shunt (zone III) increases
- PEEP acts to restore FRC by reducing zone III
COPD or any condition that causes air trapping increases FRC
*FRC cannot be measured by conventional spirometry – includes residual volume
22
Q
What tests can measure FRC?
A
Measured indirectly by:
- nitrogen washout
- helium wash in
- body plethysmography
23
Q
What increases closing volume?
A
CLOSE-P:
- COPD
- Left ventricular failure
- Obesity
- Surgery
- Extreme age
- Pregnancy
24
Q
What is the equation for oxygen-carrying capacity? What is normal?
A
CaO2 = (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
Normal = 20 mL O2/dL
*how much O2 is carried in the blood
25
What is the equation for oxygen delivery? What is normal?
DO2 = CaO2 x Cardiac Output x 10
Normal = 1000 mL O2/dL
*how much O2 is delivered to the tissues
26
What factors shift the oxyhemoglobin dissociation curve to the LEFT? (8)
Left Shift = Higher Affinity -- Left = Love
-occurs in lungs
- Decreased Temp
- Decreased 2-3-DPG
- Decreased CO
- Decreased [H+]
- Increased pH
- Increased HgbMet
- Increased HgbCO
- Increased HgbF
27
What factors shift the oxyhemoglobin dissociation curve to the RIGHT? (5)
Right Shift = Decreased Affinity --- Right = Release
-occurs near metabolically active tissue
- Increased Temp
- Increased 2,3-DPG
- Increased CO
- Increased [H+]
- Decreased pH (acidosis)
28
What are the mechanisms of CO2 transport in the blood?
Venous blood transports it to the lungs -> excreted into atmosphere
Mechanisms of CO2 Transport:
- bicarbonate = 70%
- bound to hgb = 23%
- dissolved in plasma = 7%
29
What is the Hamburger Shift?
When RBC releases HCO3 into the plasma, Chloride is transported into the RBC to maintain electroneutrality
30
What is the Bohr Effect?
Describes O2 carriage
- increase CO2 and decreased pH cause erythrocyte to release O2
- it is the cells way of asking hgb to release oxygen to support aerobic metabolism
31
What is the Haldane Effect?
Describes O2 carriage
- increased O2 causes the erythrocyte to release CO2 (occurs in the lungs)
- deoxygenated (venous) blood can carry more CO2 than oxygenated (arterial) blood
32
What are the three primary causes of hypercapnia? Provide an example of each
- Increased CO2 Production: sepsis, overfeeding, malignant hyperthermia, intense shivering, prolonged seizure activity, thyroid storm, burns
- Decreased CO2 Elimination: airway obstruction, increased dead space, increased Vd/Vt, ARDS, COPD, respiratory center depression, drug overdose, inadequate NMB reversal
- Rebreathing: exhausted soda lime, incompetent unidirectional valve in circle system, inadequate fresh gas flow in mapleson circuit
33
What are the four areas of the respiratory center in the brain?
Medullary Respiratory Centers:
- dorsal respiratory center (active during inspiration --respiratory pacemaker)
- ventral respiratory center (active during expiration)
Pontine Respiratory Centers:
- pneumotaxic center - upper pons (inhibits DRC) -- strong stimuli = rapid shallow breaths; weak stimuli = slow deep breaths
- apneustic center - lower pons (stimulates the DRC
34
Describe the location and function of the central and peripheral chemoreceptors
Central Chemoreceptors:
- located in the medulla
- responds to H+ concentration in the CSF
* H+ in CSF = function of the PaCO2 in the blood -- PaCO2 = primary stimulus to breathe
Peripheral Chemoreceptors:
- located in carotid bodies (nerves of Hering -> Glosopharyngeal n.)
- located in aortic arch (Vagus n.)
* respond to decreased O2, increased CO2, and increased H+
35
What reflex prevents over inflation of the lungs?
Hering-Breuer inflation reflex
-Lung inflation >1.5L -> CNX -> Inspiratory Off Switch -> Central Respiratory Activity -> Phrenic n. -> Inspiration Stops
36
What is hypoxic pulmonary vasoconstriction?
Minimizes shunt by reducing blood flow through poorly ventilated alveoli
- low alveolar PO2 = the trigger that activates it
- effect begins almost immediately and reaches its full effect after 15 min
37
What things impair hypoxic pulmonary vasoconstriction? What is the consequence of inhibition?
- Halogenated anesthetics > 1-1.5 MAC
- Phosphodiesterase inhibitors
- Dobutamine
- Vasodilators
Consequence = anything that inhibits it increases shunt (perfusion w/o ventilation)
*IV anesthetics do NOT inhibit
38
What does the diffusing capacity for carbon monoxide (DLCO) tell us?
It is used to assess how well the lung can exchange gas
-normal = 17-25 mL/CO/min/mmHg
Using Fick's law of diffusion, the DLCO tells us two key characteristics about alveolar-capillary interface --> surface area and thickness
*anything that reduces alveolar surface area (emphysema) and/or increases thickness (pulm fibrosis or pulm edema) reduces DLCO
39
How is tobacco smoke harmful?
- Increases SNS tone
- Increases sputum production
- Increases carboxyhemoglobin concentration
- Increases the risk of infection
40
What are the short and intermediate term benefits of smoking cessation?
Short Term does NOT reduce risk of postop pulmonary complications, but short term benefits include:
- SNS stimulating effects of nicotine dissipate after 20-30 min
- P50 returns to near normal in 12 hours (CaO2 improves)
Intermediate term:
- return of normal pulm function requires at least 6 weeks (airway function, mucociliary clearance, sputum production, pulm immune function)
* hepatic enzyme induction subsites after 6 weeks
41
How are Pulmonary Function Tests affected in obstructive disease?
- FEV1: normal or decreased if gas trapping
- FVC: normal or decreased if gas trapping
- FEV1 to FVC Ratio: decreased
- REF 25-75%: decreased
- Residual Volume: normal or increased in gas trapping
- FRC: normal or increased if gas trapping
- Total Lung Capacity: normal or increased if gas trapping
42
How are Pulmonary Function Tests affected in restrictive disease?
- FEV1: decreased
- FVC: decreased
- FEV1 to FVC Ratio: normal
- REF 25-75%: normal
- Residual Volume: decreased
- FRC: decreased
- Total Lung Capacity: decreased
43
Which of the pulmonary flow loops belongs to each:
- normal
- obstructive disease
- restrictive disease
- fixed obstruction
Obstructive: i.e. COPD
Restrictive: i.e. Pulm Fibrosis
Fixed Obstruction: i.e. Tracheal Stenosis
- extrathoracic = abnormal during inspiration
- intrathoracic = abnormal during expiration
44
What is the treatment for acute bronchospasm?
- 100% FiO2
- Deepen anesthetic (volatile agent, propofol, lidocaine, ketamine)
- Inhaled beta-2 agonist (albuterol)
- Inhaled anticholinergic (ipratropium)
- Epinephrine 1 mcg/kg IV
- Hydrocortisone 2-4 mg/kg IV (takes several hrs to take effect)
- Aminophylline
- Helium-Oxygen reduces airway resistance (decreases Reynold's number)
*Montelukast is NOT used in treatment of acute bronchospasm
45
What is alpha-1 antitrypsin deficiency? What is the treatment
- Alveolar elastase is a naturally occurring enzyme that breaks down pulmonary connective tissue -- enzyme is kept in check by alpha-1 antitrypsin (produced in liver
- When there is a deficiency alveolar elastase can wreak havoc on pulmonary connective tissue -- leads to panlobular emphysema
- Liver transplant is the definitive treatment
46
What is the goal and mechanical ventilation strategies for a pt with COPD?
Goal = prevent barotrauma and reduce air trapping
- Low tidal volume (6-8 mL/kg IBW)
- Increased expiratory time to minimize air trapping
- Slow inspiratory flow rate optimizes V/Q matching
- Low levels of PEEP are ok (as long as air trapping doesn't occur)
47
What is restrictive lung disease characterized by?
Decreased lung volumes and capacities
Decreased compliance
Intact pulmonary flow rates
48
What are examples of acute and chronic intrinsic lung diseases?
Intrinsic Lung Disease affect lung parenchyma
Acute: aspiration, negative pressure pulm edema
Chronic: pulm fibrosis, sarcoidosis
49
What are examples of extrinsic lung diseases?
Extrinsic Lung Disease affects areas around the lungs
Chest Wall/Mediastinum: kyphoscoliosis, flail chest, neuromuscular disorders, mediastinal mass
Increased Intraabdominal Pressure: pregnancy, obesity, ascites
50
What are the risk factors for aspiration pneumonitis?
- Trauma
- Emergency Surgery
- Pregnancy
- GI obstruction
- GERD
- Peptic ulcer disease
- Hiatal hernia
- Ascites
- Difficult airway management
- Cricoid pressure
- Impaired airway reflexes
- head injury
- Seizures
- Residual NMB
51
What are the pharmacologic prophylaxis of aspiration pneumonitis?
- Antacids: sodium citrate, sodium bicarb, magnesium trisilicate
- H2 Antagonists: ranitidine, cimetidine, famotidine
- GI Stimulants: metoclopramide
- PPIs: omeprazole, lansoprazole, pantoprazole
- Antiemetics: droperidol, ondansetron
* routine use of these as prophylaxis for pts NOT at risk for aspiration is NOT recommended
* anticholinergics as prophylaxis is NOT recommended
52
What is Mendelson's syndrome?
A chemical aspiration pneumonitis -- first described in OB pts receiving inhalation anesthesia
Risk Factors = Gastric pH <2.5 and Gastric volume >25 mL (0.4 mL/kg)
53
What is the treatment of aspiration?
- Tilt head down or to the side (1st action)
- Suction upper airway
- Lower airway suction is only useful for removing particulate matter (not helpful for chemical burn from gastric acid)
- Secure airway to support oxygenation
- Apply PEEP to reduce shunt
- Admin bronchodilators to reduce wheezing
- Admin lidocaine to reduce neutrophil response
- Steroids probably won't help
- Antibiotics are only indicated if the patient develops a fever or an increased WBC count >48 hrs
54
What is the pathophysiology of flail chest? How is it treated?
- It is a consequence of blunt chest trauma w/ multiple rib fractures
- Key characteristic = paradoxical movement of chest wall at site of fractures
- Inspiration (negative intrathoracic pressure) = injured ribs move inward and collapse affected region
- Expiration (positive intrathoracic pressure) = injured ribs move outward and affected region doesn't empty
Treatment = epidural catheter or intercostal nerve blocks
55
What is pulmonary hypertension? What are causes? What is the goal of anesthetic management?
Pulmonary HTN = mean PAP >25
Causes: COPD, left-sided heart disease, connective tissue disorders
Goals: optimize PVR
56
What increases Pulmonary Vascular Resistance?
- Hypoxemia
- Hypercarbia
- Acidosis
- SNS stimulation
- Pain
- Hypothermia
- Increased intrathoracic pressure (PEEP, atelectasis, mechanical ventilation)
- Drugs (nitrous oxide, ketamine, desflurane)
57
What decreases Pulmonary Vascular Resistance?
- Increased PaO2
- Hypocarbia
- Alkalosis
- Decreased intrathoracic pressure
- Preventing coughing/straining
- Spontaneous ventilation
- Drugs (inhaled nitric oxide, nitroglycerin, phosphodiesterase inhibitors, prostaglandins PGE1 and PGI2, Calcium channel blockers, ACE inhibitors)
58
What is the pathophysiology of carbon monoxide poisoning?
- Carbon monoxide reduces the oxygen carrying capacity of blood (left shift)
- It latches to the oxygen binding site on hgb w/ an affinity 200x that of O2
- Oxidative phosphorylation is impaired and metabolic acidosis results
- a co-oximeter (not pulse ox) measures CO
- pts take on a cherry red appearance (not cyanosis)
- SNS stimulation may be confused w/ light anesthesia or pain
*if soda lime is desiccated, then volatile anesthetics can produce CO (Des > Iso >>> Sevo)
59
What is the treatment of carbon monoxide poisoning?
100% FiO2 until CoHgb is less than 5% or for 6 hours
Hyperbaric oxygen if CoHgb >25% or pt is symptomatic
60
What are the absolute indications for one lung ventilation?
- Isolation of one lung to avoid contamination (infection, massive hemorrhage)
- Control of distribution of ventilation (bronchopleural fistula, surgical opening of major airway, large unilateral lung cyst, life threatening hypoxemia due to lung disease)
- Unilateral bronchopulmonary lavage (pulmonary alveolar proteinosis)
61
What are the relative indications for one lung ventilation?
- Surgical exposure (high priority): thoracic aortic aneurysm, pneumonectomy, thoracoscopy, upper lobectomy, mediastinal exposure
- Surgical exposure (low priority): middle and lower lobectomy, esophageal resection, thoracic spinal surgery
- Pulmonary edema s/p CABG or robotic mitral valve surgery
- Severe hypoxemia due to lung disease
62
How does anesthesia in the lateral decubitus position affect the V/Q relationship in the nondependent and dependent lung?
Nondependent Lung:
- moves from flatter region (less compliant) to an area of better compliance (slope)
- ventilation is optimal in this lung
Dependent Lung:
- moves from the slope to the lower, flatter area of the curve (less compliant)
- perfusion is best in this lung (effect of gravity)
- reduction of alveolar volume contributes to atelectasis
*net effect is ventilation is better in nondependent lung and perfusion is better in dependent lung -- creates V/Q mismatch and increases risk of hypoxemia during OLV
63
How do you manage hypoxemia during OLV?
1. 100% FiO2
2. Confirm DLT position with bronchoscope
3. CPAP 2-10 cmH2O to nondependent (non-ventilated) lung
4. PEEP 5-10 cmH2O to dependent (ventilated) lung
5. Alveolar recruitment maneuver
6. Clamp pulmonary artery to the non-dependent lung
7. Resume two lung ventilation
*if hypoxia is severe it is prudent to resume two lung ventilation promptly
64
What are the five indications for the use of a bronchial blocker?
Indicated for pts requiring lung separation who:
- children <8 yo (smallest DLT = 26F for 8-10 yo)
- require nasotracheal intubation
- have a tracheostomy
- have a single lumen ETT in place
- require intubation after surgery and you want to avoid changing DLT to a single lumen at the end of the case
65
How can the lumen of the bronchial blocker be used during OLV?
- Insufflate oxygen into the non-ventilated lung
- Suction air from the non-ventilated lung (improves surgical exposure)
*do NOT use to ventilate or suction blood, pus, or secretions from non-ventilated lung
66
What is mediastinoscopy and why is it performed?
Performed to obtain biopsy of the paratracheal lymph nodes at the level of the carina
Helps the surgeon stage the tumor before lung resection
67
What are the potential complications of mediastinoscopy? What is the most common?
- Hemorrhage (#1 most common)
- Pneumothorax (#2 most common)
- Thoracic aorta -> hemorrhage and reflex bradycardia
- Innominate artery -> decreased carotid blood flow and cerebral blood
- Vena cava -> hemorrhage
- Trachea -> airway obstruction
- Thoracic duct -> chylothorax
- Phrenic and recurrent laryngeal nerve injury
68
Where should you place the pulse ox and NIBP for mediastinoscopy?
Pulse Ox on right upper extremity
-if scope compresses innominate artery -> waveform dampens or disappears
NIBP on left upper extremity
-if scope compresses innominate artery -> BP reading on left arm won't be affected (allows BP measurements even if artery is compressed)
69
Describe the Mallampati score
Assesses the oropharyngeal space --- Remember PUSH
Class I: Posterior pillars, Uvula, Soft palate, Hard palate
Class II: __, Uvula, Soft palate, Hard palate
Class III: ___, ___, Soft palate, Hard palate
Class IV: ___, ___, ___, Hard palate
70
Describe the inter-incisor gap. What is normal?
Patient's ability to open the mouth directly affects ability to align the oral, pharyngeal, and laryngeal axes
-small inter-incisor gap creates a more acute angle between oral and glottic openings, increasing difficulty of intubation
Normal = 2-3 finger breaths or 4cm
71
What is the thyromental distance? What values suggest an increased risk of difficult intubation?
Thyromental distance helps estimate size of submandibular space
-tip of thyroid cartilage to tip of mentum
Laryngoscopy may be more difficult if TMD is less than 6cm (3 fingerbreadths) or greater than 9cm
72
What is the mandibular protrusion test? What values suggest an increased risk of difficult intubation?
Assesses function of temporomandibular joint
-ask pt to sublux the jaw and the position of the lower teeth compared to the position to the top
Class 1: pt can move LI past UI and bite the upper lip
Class 2: pt can move LI in line with UI
Class 3: pt cannot move LI past UI **Increased risk of difficult intubation**
73
What conditions impair atlanto-occipital joint mobility?
- Degenerative joint disease
- Rheumatic arthritis
- Ankylosing spondylitis
- Trauma
- Surgical fixation
- Klippel-Feil
- Down syndrome
74
What is the Cormack and Lehanne score?
Helps measure the view we obtain during direct vision laryngoscopy
Grade I through Grade IV
75
What are the five risk factors for difficult mask ventilation?
BONES
- Beard
- Obese (BMI >26)
- No teeth
- Elderly (age >55)
- Snoring
76
What are the 10 risk factors for difficult tracheal intubation?
- Small mouth opening
- Palate is narrow with a high arch
- Long upper incisors
- Interincisor distance <3cm
- Mallampati class III or IV
- Mandibular protrusion test class 3
- Poor compliance of submandibular space
- Thyromental distance <6cm or >9cm
- Neck is thick and short
- Limited AO joint mobility (can't touch chin to chest or extend neck)
77
What are the six risk factors for difficult supraglottic device placement?
- Limited mouth opening
- Upper airway obstruction
- Altered pharyngeal anatomy (prevent seal)
- Poor airway compliance (requires excessive PIP)
- Increased airway resistance (requires excessive PIP)
- Lower airway obstruction
78
What are five risk factors for difficult invasive airway placement?
- Abnormal neck anatomy (tumor, hematoma, abscess, hx of radiation)
- Obesity (can't ID cricothyroid membrane)
- Short neck (can't ID cricothyroid membrane)
- Limited access to cricothyroid membrane (halo, neck flexion deformity)
- Laryngeal trauma
79
What are the EBP guidelines for preop fasting?
2 hours = Clear Liquids
4 hours = Breast Milk
6 hours = Nonhuman Milk, Infant Formula, Solid Food
8 hours = Fried or Fatty Foods
*ingestion of clear liquids 2 hours before surgery reduces gastric volume and increases gastric pH
80
What is angioedema?
Result of increased vascular permeability that can lead to swelling of the face, tongue, and airway
Airway obstruction is an extreme concern
81
What are two common causes of angioedema? What is the treatment of each?
Anaphylaxis -- treat with Epi, antihistamines, and steroids
ACE Inhibitors or C1 Esterase Deficiency -- treat with icatibant, ecallantide, FFP, or C1 esterase concentrate
82
What is Ludwig's angina?
Bacterial infection characterized by a rapidly progressing cellulitis in the floor of the mouth
- inflammation and edema compress the submandibular, submaxillary, and sublingual spaces
- most significant concern is a posterior displacement of the tongue resulting in complete, supraglottic airway obstruction
83
What is he best way to secure the airway in a pt with Ludwig's angina?
With the patient awake
- awake nasal intubation
- awake tracheostomy
84
What are the 4 types of oropharyngeal airways? Which are best for fiberoptic intubation?
- Guedel (what's at UIHC)
- Berman
- Williams (for blind orotracheal intubation or fiberoptic intubation)
- Ovassapian (for fiberoptic intubation)
85
When is a nasopharyngeal airway contraindicated?
- Cribriform plate injury (risk of brain injury): LeFort 2 or 3 fracture, Basilar skull fracture, CSF rhinorrhea, Raccoon eyes, Periorbital edema
- Coagulopathy (risk epistaxis)
- Previous transsphenoidal hypophysectomy
- Previous Caldwell-Luc procedure
- Nasal fracture
86
What is the maximum recommended cuff pressures for and ETT and LMA?
ETT < 25 cmH2O
LMA < 60 cmH2O
87
What is the largest size ETT that can pass through each LMA size?
```
Size 1 : 3.5 ETT
Size 1.5 : 4.0
Size 2 : 4.5
Size 2.5 : 5.0
Size 3 : 6.0
Size 4 : 6.0
Size 5 : 7.0
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88
What is the maximum recommended peak inspiratory pressures for an LMA-Unique, LMA-Proseal, and LMA-Supreme?
LMA-Unique = < 20 cmH2O
LMA-ProSeal = < 30 cmH2O
LMA-Supreme = < 30 cmH2O
89
What are the five indications for the Bullard Laryngoscope?
Bullard laryngoscope = rigid, fiberoptic device used for indirect laryngoscopy
- Small mouth opening (minimum = 7mm)
- Impaired cervical spine mobility
- Short, thick neck
- Teacher Collins syndrome
- Pierre-Robin sequence
90
When is the best time to use an Eschmann introducer (Bougie)?
When a grade 3 view is obtained during laryngoscopy (grade 2 is the next best time)
*During a grade 4 view, the likelihood of successful intubation is unacceptably low
91
What is the proper placement of the lighted stylet?
When lighted stylet is in the trachea, the light has to travel through less tissue, so you'll observe a well-defined circumscribed glow below the thyroid prominence
-when it is in the esophagus - more diffuse transillumination of the neck without circumscribed glow
92
What are two indications for retrograde intubation?
Unstable cervical spine (most common use)
Upper airway bleeding -- can't visualize glottis
*use when intubation has failed but ventilation is still possible
93
What are the pros and cons of awake extubation?
PROS:
- airway reflexes intact
- ability to maintain airway patency
- decrease risk of aspiration
CONS:
- increased CV and SNS stimulation
- increased coughing
- increased intracranial pressure
- increased intraoccular pressure
- increased intraabdominal pressure
94
What are the pros and cons of deep extubation?
PROS:
- decreased CV and SNS stimulation
- decreased coughing
CONS:
- airway reflexes are ineffective
- increased risk of airway obstruction
- increased risk of aspiration
95
When is the best time to use an airway exchanger catheter? What can you do with it?
It is a long, thin, hollow tube that maintains direct access to the airway following tracheal extubation
-Common device used to manage extubation of the difficult airway
You can also:
- measure EtCO2
- Jet ventilation (via luer-lock adapter)
- oxygen insufflation (via 15mm adapter)
