UNIT 1 Respiratory & Airway 🫁 Flashcards
Which muscles tense and relax the vocal cords?
Tense: CricoThyroid
Relax: ThyroaRytenoid
The CricoThyroid muscle tenses the vocal cords, while the ThyroaRytenoid muscle relaxes them.
Which muscles abduct and adduct the vocal cords?
Abduct: Posterior CricoArytenoid
Adduct: Lateral CricoArytenoid
The Posterior CricoArytenoid muscle opens the vocal cords, while the Lateral CricoArytenoid muscle closes them.
Describe the sensory innervation of the upper airway.
Trigeminal (CN5):
* V1 – ophthalmic – nares, anterior 1/3 septum
* V2 – maxillary – turbinate’s & septum
* V3 – mandibular – anterior 2/3 tongue
Glossopharyngeal (CN 9):
* posterior 1/3 tongue
* soft palate
* oropharynx
* vallecula
* anterior side of epiglottis
SLN – internal branch:
* posterior epiglottis to vocal cords
RLN:
* below vocal cords to trachea
Sensory innervation is crucial for procedures like fiberoptic intubation and airway blocks.
How does RLN injury affect the integrity of the airway?
Bilateral: acute = respiratory distress, chronic = none
Unilateral: none
RLN injury can lead to significant airway complications depending on whether it is bilateral or unilateral.
How does SLN injury affect the integrity of the airway?
Bilateral: hoarseness / none
Unilateral: none
SLN injury primarily affects voice quality without significant airway obstruction.
Name 3 airway blocks and identify the key landmarks for each.
- Glossopharyngeal block – palatoglossal arch at anterior tonsillar pillar
- SLN block – greater cornu of hyoid bone
- Transtracheal block – cricothyroid membrane
Understanding these landmarks is vital for effective airway management.
What are the 3 paired and 3 unpaired cartilages of the larynx?
Paired:
* Corniculates
* Cuneiforms
* Arytenoid
Unpaired:
* Epiglottis
* Thyroid
* Cricoid
The cartilages play essential roles in vocalization and airway protection.
What is the treatment for laryngospasm?
- Larson’s Point maneuver
- Positive pressure / CPAP 15-20cmH2O
- 100% FiO2
- Remove noxious stimulation
- Deepen anesthesia
- Open airway (chin lift, head extension)
- Suxx
Infants/small children should receive 0.02mg/kg Atropine with Suxx; Suxx is contraindicated in certain cases.
Describe how the respiratory muscles function during the breathing cycle.
Inspiration:
* Diaphragm contracts, increasing thoracic volume
* External intercostals contract, increasing A/P dimension
* Accessory muscles: sternocleidomastoid + scalene
Exhalation:
* Passive usually, active in conditions like COPD
* Forced exhalation involves abdominal musculature
The mechanics of breathing rely on muscle contractions and lung recoil.
What is the difference between minute ventilation (Ve) and alveolar ventilation (VA)?
Ve = RR x Vt
VA = (Vt – anatomic dead space) x RR
VA measures the volume available for gas exchange, while Ve includes all ventilation.
Define the 4 types of dead space (Vd).
- Anatomic – conducting airway
- Alveolar – vented but not perfused
- Physiologic = Alveolar + Anatomic
- Apparatus – equipment
Understanding dead space is critical for assessing ventilation efficiency.
What does the V/Q ratio represent?
V/Q = ventilation / perfusion
Normal V/Q = 0.8
> 0.8 = dead space
< 0.8 = shunt
The V/Q ratio is essential for understanding lung function and gas exchange.
Define the West Zones of the lung.
Zone 1: PA > Pa > Pv (dead space)
Zone 2: Pa > PA > Pv (waterfall, normal)
Zone 3: Pa > Pv > PA (shunt)
Zone 4: Pa > Pist > Pv > PA
These zones describe regional variations in blood flow and ventilation in the lungs.
Recite the alveolar gas equation.
Alveolar Oxygen = [FiO2 x (Pb – PH2O) – (PaCO2 / RQ)]
This equation illustrates the relationship between various factors affecting alveolar oxygen concentration.
What is the A-a gradient and what factors affect it?
A-a gradient = PAO2 - PaO2
< 15 mmHg is normal
Increased by: high FiO2, aging, vasodilators, R to L shunts, diffusion limitation
A-a gradient helps diagnose hypoxemia causes by quantifying venous admixture.
List the 5 causes of hypoxemia.
- Hypoventilation
- V/Q mismatch
- Shunt
- Diffusion impairment
- Low inspired oxygen
Supplemental oxygen can reverse some causes, primarily those related to hypoventilation and V/Q mismatch.
Define the capacities and give reference values for each.
TLC – 6L
VC – 4.5L
IC – ~ 3.5L
FRC - ~ 2.3L
Lung capacities are important for assessing respiratory function.
What factors influence FRC?
FRC = RV + ERV (35 ml/kg)
Decreased FRC: anything that reduces outward lung expansion
FRC is crucial in understanding lung mechanics and can be affected by various conditions.
What tests can measure FRC?
- N2O washout
- Helium wash in
- Body plethysmography
These tests provide valuable information about lung volumes that spirometry cannot measure.
What is closing volume and what increases it?
Closing volume is the volume above RV where small airways collapse during expiration. Increased by: CLOSE-P
* C – COPD
* L – LVF
* O – obesity
* S – surgery
* E – extreme age
* P – pregnancy
Closing volume is important for understanding airflow limitation in lung diseases.
State the equation and normal value for oxygen-carrying capacity.
(1.34 x Hgb x SaO2) + (PaO2 x 0.003) = CaO2
Normal – 20 mL O2/dL
This equation quantifies the amount of oxygen carried in the blood.
State the equation and normal value for oxygen delivery.
DO2 = CaO2 x CO x 10
Normal – 1000 mL O2/min
Oxygen delivery is critical for assessing tissue oxygenation.
Discuss the factors that alter the oxyhgb dissociation curve.
Left shift = LOVES O2 (Lungs):
* ↓ temp
* ↓ CO2
* ↓ 2,3 DPG
* ↓ H+
* alkalosis (↑ pH)
* ↑ HgbMET, HgbF, HgbCO
Right shift = RELEASE O2 (Hot, exercising muscle):
* ↑ temp
* ↑ CO2
* ↑ 2,3 DPG
* ↑ H+
* acidotic (↓ pH)
Understanding the shifts in the curve helps in managing patients with respiratory issues.
How is carbon dioxide transported in the blood?
- Bicarbonate = 70%
- Bound to Hgb = 23%
- Dissolved in plasma = 7%
The majority of carbon dioxide is transported as bicarbonate, which plays a significant role in acid-base balance.
Describe the Bohr effect.
↑ CO2 + ↓ pH = erythrocyte to release O2 (occurs in tissues)
The Bohr effect describes how increased carbon dioxide and decreased pH promote oxygen release in tissues.
Describe the Haldane effect.
↑ O2 = erythrocyte to release CO2 (occurs in lungs)
The Haldane effect explains how oxygenation of hemoglobin promotes carbon dioxide release.
List the 3 primary causes of hypercapnia and provide examples of each.
- Increased CO2 production (e.g., fever)
- Decreased ventilation (e.g., COPD)
- Impaired gas exchange (e.g., pulmonary edema)
Understanding the causes of hypercapnia is essential for respiratory management.
Describe the 4 areas in the respiratory center.
- Dorsal respiratory center/group (DRG) – active during inspiration
- Ventral respiratory center – active during expiration
- Pneumotaxic center (upper pons) – inhibits DRG
- Apneustic center (lower pons) – stimulates DRG
These centers coordinate the rhythm and rate of breathing.
Contrast the location and function of the central and peripheral chemoreceptors.
Central: medulla, responds to [H+] in CSF
Peripheral: carotid bodies (CN9), aortic arch (CN10), responds to ↓ O2, ↑ CO2, ↑ H+
The central chemoreceptors primarily respond to changes in carbon dioxide levels, while peripheral chemoreceptors respond to oxygen levels.
Which reflex prevents overinflation of lungs?
Hering-Breuer inflation reflex (CNX = afferent)
This reflex is a protective mechanism that helps regulate breathing patterns.
What is hypoxic pulmonary vasoconstriction?
HPV occurs in lung parts not getting ventilated (V/Q = 0), shunting blood to ventilated alveoli
This mechanism helps optimize ventilation-perfusion matching in the lungs.
What things impair HPV? What is the consequence of this?
Anything that increases perfusion to lungs (D.H.P.V.):
* Dobutamine
* Halogenated agents, MAC >1-1.5
* Phosphodiesterase inhibitors
* Vasodilators
Impairment of HPV can worsen shunting and V/Q mismatch.
What does the diffusing capacity for Carbon Monoxide tell us?
DLCO assesses how well the lung exchanges gas. Normal = 17-25 mL/CO/min/mmHg
A reduced DLCO indicates issues with the alveolar-capillary interface.
How is tobacco smoke harmful?
- ↑ SNS tone (nicotine)
- ↑ sputum production
- ↑ [carboxyhgb]
- ↑ risk of infection
Tobacco smoke has multiple detrimental effects on respiratory health.
Describe the short and intermediate-term benefits of smoking cessation.
Short:
* Does NOT ↓ risk of postop pulmonary complications
* ↓ SNS in 20-30 mins
Intermediate:
* 6 weeks – normal pulmonary function
Smoking cessation leads to rapid improvements in respiratory function and health.
Compare/contrast PFTs in obstructive vs. restrictive lung disease.
Obstructive: ↓ FEV1, normal or ↑ FVC
Restrictive: ↓ FVC, normal or ↑ FEV1/FVC ratio
Understanding PFT results is essential for diagnosing lung diseases.
Discuss pulmonary flow-volume loops: normal, obstructive, restrictive, fixed obstructive.
Normal: upside down ice cream cone
Obstructive: large volume with expiratory obstruction
Restrictive: smaller volume upside down ice cream cone
Fixed: both inspiration & expiration are fixed
Flow-volume loops visually represent lung function and pathology.
Give examples of a disease that produces obstructive, restrictive, and fixed obstructive flow-volume loops.
Obstructive: COPD
Restrictive: sarcoidosis, fibrosis
Fixed obstructive: tracheal stenosis
Identifying these diseases helps in managing respiratory conditions.
What is the treatment for acute bronchospasm?
- 100% FiO2
- Deepen anesthetic agents
- Inhaled anticholinergic (ipratropium)
- Epi 1mcg/kg IV
- Hydrocortisone 2-4mg/kg IV
- Aminophylline (PDE-i)
- Heliox
These treatments target bronchospasm effectively, improving airway function.
What is alpha-1 antitrypsin deficiency?
Deficiency leads to unchecked alveolar elastase activity, resulting in panlobular emphysema. Liver transplant is definitive treatment.
Understanding this condition is key for managing emphysema and liver health.
Describe goals and strategies for mechanical venting in COPD patients.
- Prevent barotrauma
- Decrease air trapping
- Low Vt (6-8ml/kg IBW)
- Increase E time
- Slow inspiratory flow rate
- Low level PEEP
These strategies help optimize ventilation in patients with COPD.
Define restrictive lung disease.
Characterized by ↓ lung volumes and capacities, ↓ compliance, with intact pulmonary flow rates.
Recognizing restrictive lung disease is crucial for appropriate treatment.
Give examples of intrinsic lung diseases (acute and chronic).
Acute: aspiration, negative pressure pulmonary edema
Chronic: fibrosis, sarcoidosis
These conditions affect lung function and require different management approaches.
Give examples of extrinsic lung diseases (acute and chronic).
Acute: flail chest, neuromuscular disorders
Chronic: kyphoscoliosis, mediastinal mass
Extrinsic factors can significantly impact lung function.
List risk factors for aspiration pneumonitis.
- Decreased consciousness
- Gastroesophageal reflux
- Mechanical ventilation
- Intubation
Identifying risk factors helps in preventing aspiration events.
What is Mendelson’s syndrome?
Chemical aspiration pneumonitis in OB patients receiving inhalation anesthesia with gastric pH <2.5 and gastric volume > 25mL.
This syndrome highlights the importance of gastric contents during anesthesia.
Describe the treatment of aspiration.
- Tilt head down or to side
- Suction upper airway
- Suction lower airway
Immediate action is crucial in managing aspiration to minimize lung injury.
What is obesity?
A condition characterized by excessive body fat accumulation.
Obesity is often defined by a Body Mass Index (BMI) of 30 or higher.
What is ascites?
The accumulation of fluid in the peritoneal cavity.
Ascites is often associated with liver cirrhosis and other medical conditions.
List risk factors for aspiration pneumonitis.
- Obesity
- Ascites
- Impaired consciousness
- Difficulty swallowing
- Gastroesophageal reflux disease
Describe the pharmacologic prophylaxis of aspiration pneumonitis.
Use of drugs to reduce gastric acidity and volume prior to surgery.
Common agents include H2 receptor antagonists and proton pump inhibitors.
What is Mendelson’s syndrome?
Chemical aspiration pneumonitis first described in obstetric patients receiving inhalation anesthesia.
What are the gastric pH and volume criteria for aspiration risk?
Gastric pH < 2.5 and gastric volume > 25 mL (0.4 mL/kg).
Describe the treatment of aspiration.
- Tilt head down or to the side
- Suction upper airway
- Secure airway to support oxygenation
- Use PEEP to reduce shunt
- Administer bronchodilators
- Lidocaine to reduce neutrophil response
- Antibiotics only if fever or increased WBC > 48 hours
- Steroids won’t help.
What causes flail chest?
Usually results from blunt trauma with multiple rib fractures.
What is the key characteristic of flail chest?
Paradoxical chest movement at the injury site.
What is pulmonary hypertension?
Increased pulmonary artery pressure (PAP) > 25 mmHg.
List causes of pulmonary hypertension.
- COPD
- Left heart disease
- Connective tissue disorders
What are the goals of anesthetic management in pulmonary hypertension?
Optimize pulmonary vascular resistance (PVR).
Discuss the pathophysiology of carbon monoxide poisoning.
- 200x affinity for hemoglobin compared to oxygen
- Causes a left shift in the oxygen dissociation curve
- Impairs oxidative phosphorylation, leading to metabolic acidosis.
What is the treatment for carbon monoxide poisoning?
- 100% Fio2 until carboxyhemoglobin < 5% for 6 hours
- Hyperbaric oxygen if carboxyhemoglobin > 25% or symptomatic.
List absolute and relative indications for one-lung ventilation (OLV).
- Absolute indications:
- Surgical access to the lung
- Relative indications:
- Unilateral lung disease
- Hemodynamic instability
How does lateral decubitus position affect V/Q relationship?
- Non-dependent lung (up lung) has better ventilation
- Dependent lung (down lung) has better perfusion
- Results in V/Q mismatch.
What is the management of hypoxemia during one-lung ventilation?
- 100% Fio2
- Confirm double-lumen tube position with bronchoscope
- Use CPAP on up lung
- PEEP on down lung
- Clamp pulmonary artery to non-dependent lung if severe.
List 5 indications for the use of a bronchial blocker.
- Child < 8 years
- Non-traumatic intubation
- Tracheostomy
- Single lumen endotracheal tube in place
- Need intubation postoperatively.
How can the lumen of the bronchial blocker be used during OLV?
- Insufflate oxygen into non-vented lung
- Suction air from non-vented lung
- Cannot be used for ventilation.
What is mediastinoscopy and why is it performed?
A procedure to obtain biopsy of paratracheal lymph nodes at the level of the carina.
What are the potential complications of mediastinoscopy?
- Hemorrhage
- Pneumothorax
- Injury to thoracic aorta
- Injury to innominate artery
- Injury to vena cava
- Airway obstruction
- Chylothorax
- Phrenic nerve injury.
Where should you place the pulse oximeter and non-invasive blood pressure (NIBP) for mediastinoscopy?
- SpO2: Right upper extremity
- NIBP: Left upper extremity.
Describe the Mallampati score.
- 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 only.
What is the normal inter-incisor gap?
2-3 finger breadths (4 cm).
What is thyromental distance and its significance?
Distance from tip of thyroid cartilage to tip of mentum; < 3 fingerbreadths (6 cm) indicates increased risk for difficult intubation.
What is the mandibular protrusion test?
Test of temporomandibular joint function; Class 3 indicates increased risk of difficult intubation.
What conditions impair atlanto-occipital joint mobility?
- Degenerative joint disease
- Rheumatoid arthritis
- Ankylosing spondylitis
- Trauma
- Surgical fixation
- Klippel-Feil syndrome
- Down syndrome.
List 5 risk factors for difficult mask ventilation.
- Beard
- Obesity (BMI > 26 kg/m2)
- No teeth
- Elderly (> 55 years)
- Snoring.
List 10 risk factors for difficult tracheal intubation.
- Small mouth opening
- Narrow and high arch palate
- Long upper incisors
- Interincisal distance < 3 cm
- Mallampati 3-4
- Mandibular protrusion test Class 3
- Poor compliance of submandibular space
- Thyromental distance < 6 cm
- Short, fat neck
- Limited atlanto-occipital joint mobility.
List 6 risk factors for difficult supraglottic device placement.
- Small mouth opening
- Upper airway obstruction
- Altered pharyngeal anatomy
- Poor airway compliance
- Increased airway resistance
- Lower airway obstruction.
List 5 risk factors for difficult invasive airway placement.
- Abnormal neck anatomy
- Obesity
- Short neck
- Limited access to cricothyroid membrane
- Laryngeal trauma.
Describe the Practice 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 food.
What is angioedema?
Result of increased vascular permeability leading to swelling of face, tongue, and airway.
What are 2 common causes of angioedema?
- Anaphylaxis
- ACE-inhibitor use.
What is Ludwig’s angina?
A bacterial infection characterized by rapidly progressing cellulitis in the floor of the mouth.
What is the best way to secure the airway in a patient with Ludwig’s angina?
Awake intubation.
List the 4 types of oral airways (OAs).
- Guedel
- Berman
- Nasopharyngeal
- Oropharyngeal.
When is a nasopharyngeal airway contraindicated?
- Cribriform plate injury
- Lefort 2 or 3 fractures
- Basilar skull fractures
- CSF rhinorrhea.
What is the maximum recommended cuff pressure for an ETT?
< 25 cmH2O.
What is the largest size ETT that can be passed through an LMA 3?
6.
What is the maximum recommended PIP for LMA-Unique?
< 20 cmH2O.
List 6 indications for the Bullard laryngoscope.
- Small mouth opening
- Impaired cervical spine mobility
- Short, thick neck
- Treacher-Collins syndrome
- Pierre-Robin sequence.
When is the best time to use an Eschmann introducer?
When a grade 3 view is obtained during direct laryngoscopy.
Describe the proper placement of the lighted stylet.
Position in the trachea shows better light; diffuse light indicates esophagus.
List 2 indications for retrograde intubation.
- Unstable cervical spine
- Upper airway bleeding.
What paralytic and reversal agent is recommended for suspected difficult airway?
Rocuronium + Sugammadex.
What 4 risk factors should prompt consideration of awake intubation?
- Suspected difficult mask ventilation
- Suspected difficult ventilation with supraglottic airway
- Increased risk of aspiration
- Increased risk of rapid desaturation.
When is the best time to use an airway exchanger catheter?
When maintaining access to the airway after tracheal excavation.
