Airway management Flashcards
Name the components of the upper respiratory tract.
◉ It refers to the structures that are located above the larynx, outside of the thorax, and it consists of:
* Nose, nasal cavity and paranasal sinuses (seio paranasal).
* Mouth
* Pharynx
➜ Pharynx consists of:
* Nasopharynx
* Oropharynx
* Laryngopharynx
Name the components of the lower respiratory tract.
- Larynx
- Tracheobronchial tree
Name the components of the larynx.
- Eppiglottis
- Supraglottis
- Vocal cords
- Glottis
- Subglottis
Describe the composition and division of the tracheobronchial tree.
Lower resp. tract
► The tracheobronchial tree is composed of 23 divisions / generations, that become progressively narrower (with each division) from the trachea to the alveoli (and ⬆︎ its cross-sectional area as it progresses).
➔ The tracheobronchial tree can further be subdivided into:
* Conducting zone
* Respiratory zone
Name the structures that compose the conducting zone of the tracheobronchial tree.
Lower respiractory tract
◉ Airways generations 0-16
➜ 0: Trachea
➜ 1: Main bronchi
➜ 2: Lobar bronchi
➜ 3-4: Segmental bronchi
➜ 5-11: Subsegmental bronchi
➜ 12-15: Bronchioles
➜ 16: Terminal bronchioles
◉ Cartilaginous airways: 0-11
◉ Non-cartilaginous: 12-16
Name the structures that compose the respiratory zone of the tracheobronchial tree.
◉ Airways generations 17-23
➜ 17-19: Respiratory bronchioles
➜ 20-22: Alveolar ducts
➜ 23: Alveolar sacs
Describe the sensory innervation of the mucous membranes of the nasal passages.
Sensory innervation of the upper and lower airway.
- Anteriorly: ophthalmic division of the trigeminal nerve;
- Posteriorly: maxillary division of the trigeminal nerve.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation of the soft and hard palate.
The palatine nerves.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation of the tongue.
- Anterior two-thirds of the tongue: lingual nerve (the mandibular branch of trigeminal nerve);
- Posterior one-third of the tongue: glossopharyngeal nerve.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation of the:
- Tonsils
- Pharyngeal roof
- Parts of the soft palate
The glossopharyngeal nerve.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation of the upper airway below the epiglottis.
Branches of the vagus nerve.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation between the epiglottis
and larynx.
The superior laryngeal nerve.
Sensory innervation of the upper and lower airway.
Describe the sensory innervation between the larynx and trachea.
Recurrent laryngeal nerve.
What components of the physical examination are important in airway evaluation during the preoperative assessment?
➜ Inspection of the patient’s physical appearance noting:
- Morbid obesity,
- Frailty,
- Mental status.
➜ Inspection of the face and neck for anything suggestive of a difficult airway:
- Short neck,
- Inability to fully flex and/or extend the neck,
- Large neck circumference (>42 cm),
- Evidence of prior operations (especially tracheostomy),
- Abnormal neck masses (including but not limited to tumor, goiter, hematoma, abscess, or edema).
➜ Mouth:
- Small mouth opening (interincisor distance <3 cm);
- Large tongue;
- Micrognathia;
- Short thyromental distance (<3 finger breadths);
- Mallampati score of III or IV;
- Inability to bite the upper lip.
➜ Dentition:
- Document teeth that are chipped, missing, or loose;
- Elective case and high risk for tooth dislodgement: see a dentist for extraction before the case;
- Loose or removable dental appliances: removed before anesthesia (can impede airway management or pose an aspiration risk);
- Edentulous: direct laryngoscopy and intubation may be easier, but mask ventilation may prove more challenging.
What components of the patient history are important in airway evaluation during the preoperative assessment?
◉ Ask the patient about prior anesthetics
- May provide important information that could alert the practitioner to have additional personnel or airway management equipment immediately available.
◉ Previous anesthetic records (if available)
➜ Can provide information about airway management problems in the past including:
- Mask ventilation;
- Intubation;
- Special airway techniques or equipment required for successful airway management.
◉ Inquire about previous medical interventions or trauma that may have implications on airway management
- Cervical spine injury or surgery;
- History of tracheostomy;
- Head and neck surgery;
- Head and neck radiation treatment;
- Congenital craniofacial abnormalities;
- Predisposition to atlantoaxial instability (e.g., rheumatoid arthritis, achondroplasia, Down syndrome).
What are the predictors of difficult mask ventilation?
• > 55 years
• Obesity
• Presence of a beard
• Snoring & OSA
• Lack of teeth
• Retrognathia (posterior displacement of mandible).
Define what is the Mallampati classification.
It is a scoring system used to predict the difficulty of intubation when combined with other features of the airway examination that are suggestive of a difficult intubation.
Describe each component of the Mallampati classification.
0. Visualization of any part of the epiglottis
I. Tonsillar pillars, uvula, and soft palate
II. Base of uvula and soft palate
III. Soft palate only
IV. Hard palate only
How to examine a patient in order to to assess the Mallampati classification?
The patient must be:
* Sitting upright
* With the head neutral
* Mouth open
* Tongue protruded
* And not phonating.
What are the general indications for endotracheal intubation? How does this apply to general anesthesia?
◉ There are 3 main indications to intubate a patient:
❖ Inability to protect airway (e.g., altered mental status)
❖ Hypercapnic respiratory failure / type 2 (COPD)
❖ Hypoxemic respiratory failure / type 1 (ARDS)
➜ Patients under general anesthesia are primarily intubated for airway protection to prevent aspiration.
➜ Secondarily because of hypercapnic respiratory failure due to general anesthetic agents and opioids causing suppression of respiratory drive (not an absolute indication for endotracheal intubation, as mask ventilation or placement of a supraglottic airway can treat temporary hypercapnic respiratory from general anesthesia in short surgical operations).
What equipment should I have available when planning to intubate a patient?
◉ Airway management equipment❖ Appropriately fitting mask❖ Laryngoscope / video laryngoscope / flexible bronchoscope❖ Endotracheal tube (in multiple sizes)❖ Oral and/or nasal airways❖ Adhesive tape❖ Suction❖ Supraglottic airway❖ Bag-valve-mask device (ambu bag)❖ O₂ source (anaesthesia machine / ventilator)
◉ Monitors
❖ Blood pressure
❖ Oximeter
❖ ECG
❖ End-tidal CO₂ (ETCO₂)
❖ Stethoscope (to confirm correct endotracheal tube placement)
◉ Medications❖ Sedatives / hypnotics❖ Short acting paralytics❖ Vasopressors (in emergency)
Vasopressors for emergency for hemodynamic management.
What is the purpose of preoxygenation before the induction of anesthesia?
❖ To increase the safe apnea time before intubation.
❖ Avoiding desaturation SpO₂ <90%.
❖ When the patient inhales 100% O₂ it denitrogenates the lungs.
❖ Filling the FRC with 100% O₂ and ⬆︎ the safe apnea time to 5 min.
What is the clinical relevance of blood gas changes in apnoea?
➜ In total, the circulation and lungs contain approximately 2.5 L of immediately available CO₂ and 1550 mL of O₂.
◆ If a healthy patient stops breathing (e.g. on induction of general anaesthesia), basal processes will continue: 250 mL/min of O₂ will be consumed and 200 mL/min of CO₂ will be produced.
◆ Therefore PCO₂ will ⬆︎.
◆ PO₂ will ⬇︎.
◆ Typically, SaO₂ falls to 70% (PO₂ 5.0 kPa) after 2 min.
► If the patient breathes O₂ for sufficient time to completely de-nitrogenate their FRC prior to the period of apnoea, the quantity of stored O₂ ⬆︎ to over 3 L.
► Even after 5 min of apnoea, SaO₂ will remain at 100%.
◉ Basal metabolic processes will continue, and after 5 min the PaCO₂ will approach 10 kPa.
What is a rapid sequence induction of anesthesia and intubation?
Method of rapidly secure an airway with an endotracheal tube in a patient who is at increased risk of aspiration.
Explain how is RSI performed.
𝟭. Preoxygenation
2. Rapid injection of anesthetic agents and a rapid onset paralytic (succinylcholine or double dose rocuronium).
3. Avoidance of mask ventilation (to minimize gastric insufflation).
4. Immediate laryngoscopy and intubation, following induction.
5. An assistant to provide cricoid pressure (CP) to block gastric contents from causing aspiration.
6. Avoidance of other medications before induction of anesthesia that can precipitate aspiration, such as benzodiazepines or opioids.
If necessary, mask ventilation can be performed if hypoxemia ensues and the provider is unable to intubate ideally with CP being applied (modified RSI).
What patients are at risk of aspiration?
Patients with a full stomach
• Patients who have not fasted accordingly or fasting status unknown.
• Emergency surgery patients.
• Trauma patients.
Pregnancy
• After 20 weeks gestation.
• Earlier if symptoms of gastroesophageal reflux.
Patients with increased abdominal pressure
• Ascites
• Abdominal mass
• Morbid obesity BMI >= 40 kg/m2
Patients with gastrointestinal pathology
• Gastroparesis or delayed gastric emptying (diabetic neuropathy, patients taking GLP-1 receptor agonists).
• Small bowel obstruction
• Gastric outlet obstruction
• Oesophageal cancer
• Oesophageal stricture
• Gastroesophageal reflux disease
Describe the Cormack-Lehane classification (laryngoscopy view).
• Grade 1: Full view of glottis.
• Grade 2a: Partial view of glottis.
• Grade 2b: Posterior glottis or posterior arytenoids seen only.
• Grade 3: Only epiglottis seen.
• Grade 4: Neither glottis nor epiglottis seen.
Describe supraglottic airways devices.
• Are devices that are inserted into the pharynx above the glottis to facilitate ventilation.
• They can be used for both spontaneous (negative pressure) and mechanical (positive pressure) ventilation.
• They do not require the use of neuromuscular blockade for placement.
• They are generally used in healthy patients undergoing short operations (i.e., 1–2 hours).
• Can also
be used as a rescue device in patients who are difficult to intubate or as a conduit to facilitate flexible
scope intubation.
• Disadvantages include the lack of protection from laryngospasm or aspiration of gastric contents.
When is a patient considered safe to extubate?
1- They’re awake and can protect their airway (exhibiting airway reflexes, such as gagging on the endotracheal tube)
2- Patient is not in hypoxemic respiratory failure.
3- Patients are not in hypercapnic respiratory failure (this includes residual paralysis, overdose of opioids, or airway edema).
4 - Patients are hemodynamically stable.
5 - adequate reversal of neuromuscular blockade.
Describe the preparation for extubation.
• Placement of an oropharyngeal airway.
• Preoxygenation with a fraction of inspired oxygen of 100%.
• Suctioning of the oropharynx.
• In patients at high risk for aspiration, decompression of the stomach with an orogastric tube and placement of the patient in the head up position.
Why is it important to place an oropharyngeal airway in the patient’s mouth before emergence and extubation?
• It displaces the tongue off the posterior oropharynx and palate, preventing obstruction of the upper airway and impedance of gas flow.
• Can be used as a bite block to prevent the development of negative pressure pulmonary edema, which can occur if the patient were to bite down on the endotracheal tube and attempt to inspire a large tidal volume.
