ENT II Flashcards
1
Q
What is the goal for ENT anesthesia?
What are the factors affecting airway safety?
A
- The provision of a clear, free, and unobstructed airway is the principal concern for all ENT procedures
- Factors affecting airway safety:
- patient factors
- remote surgery
- surgical factors
- shared airway
2
Q
What are the general principles of ENT anesthesia?
(10)
A
- simple
- provide complete control of the airway with no risk of aspiration
- control ventilation with adequate oxygenation and CO2 removal
- provide smooth induction and maintenance of anesthesia
- provide a clear, motionless surgical field
- free of secretions
- not impose time restrictions on the surgeon
- not be associated with any risk ofairway fire or CV instability
- allow safe emergence with no coughing, bucking, breath holding, laryngospasm
- produce a pain-free, comfortable, alert pt at the end
3
Q
What does pre-operative stridor imply?
A
airway diameter < 4-5 mm
(nml is about 10 mm)
4
Q
Why are anticholinergics used in airway surgery?
Corticosteroids?
A
- Anticholinergics
- reduces vagal tone
- reduces secretions
- increases bronchodilation
- Corticosteroids
- decrease edema formation
- reduce nausea and vomiting
- prolong analgesic effects of LA
5
Q
Why might PONV be worse with airway surgery?
Why might you want an A-line in an airway surgery?
A
- blood in stomach
- throat pack used to prevent this, make sure it is removed before you extubate.
- A-line for deliberate controlled hypotension (MAP 60-70)
6
Q
What are some post-op considerations for airway surgery?
A
- Have head up to decrease edema
- observe for bleeding and edema
- administer humidified oxygen
- watch for pneumothorax
- venturi effect sucks in surrounding air
- watch for respiratory failure
- steroids and racemic epi mist can help control laryngeal edema
7
Q
What is the closed system technique that can be used for airway surgery?
What are the advantages and disadvantages?
A
- Uses smaller sized (4-5mm) cuffed ETT
- Advantage:
- routine technique
- protection of lower airway
- control of airway
- control of ventilation
- minimal pollution of VA
- Disadvantages:
- Surgical access and visibility limited
- high ventilation pressures needed with small ETT tubes
- vocal cord damage with intubation
- Risk of laser airway fire
8
Q
How is the closed system with cuffed ETT done?
A
- Small ETT 4-5 mm
- Microlaryngoscopy tube-long, small tube with high-volume, low-pressure cuffs
- Laser tubes- metal, fire resistant tube
- can have no cuff or double cuff
- Be sure to prevent extubation, disconnects, and leaks
- Assess ventilation continually
- observe chest movement, auscultation, pulse-ox, ETCO2, blood gas analysis
- Orchestrate turning
9
Q
What are the open systems?
What are the advantages and disadvantages?
A
- Open systems-
- spontaneous ventilation and insufflation techniques
- muscle paralysis and jet ventilation
- Advantages:
- Laser safety
- reduced risk of ETT-related trauma
- complete laryngeal visualization
- Disadvantages:
- unprotected lower airway
- lack of control of ventilation
- operating room polution
- specialized knowledge, equipment, and experience required.
10
Q
How is the spontaneous ventilation with insufflation technique of the open system done?
A
- Pt remains spontaneously breathing with natural airway
- Anesthetic gases insufflated via:
- a small catheter in nasopharynx and above laryngeal opening
- tracheal tube cut short and placed in nasopharynx emerging just beyond soft palate
- nasopharyngeal airway
- side-arm channel of laryngoscope or bronchoscope
11
Q
How is the open system Jet ventilation technique done?
A
- **pt is paralyzed and apneic
- Subglottic jet ventilation by:
- jetting needle attached to a laryngoscope or bronchoscope
- transtracheal catheter thru cricothyroid membrane
- small-diameter (2-3 mm), cuffed/uncuffed ETT specifically designed for jet ventilation
- High frequency (>1 Hz, 60 breaths/min) with ventilator rates 100-150/min
- automated high-frequency ventilators with alarms and automatic interruption if pressure limits are reached
12
Q
What is the difference between hand triggered jet ventilation and using an oscillator?
A
- Hand-triggered devices-
- usually low-frequency jet ventilation (8-10 breaths per min) to allow adequate time for exhalation via passive recoil of lung and chest wall
- prevents air-trapping and build-up of pressure in small airways
- Ventilate at low pressures of 30-50psi. [least amount possible]
- Inspiration is 1.5secs, expiration 6secs
- High-frequency jet ventilators (oscillatory ventilation)
- jets gas at 1-10 Hz
- both inspiration and expiration are active
- driving pressure, frequency, inspiratory time, and composition of jet gas can
be adjusted - RR up to 100bpm
13
Q
What is the process for doing an anesthetic with Jet ventilation?
A
- Preoxygenation
- IV induction
- NDMR
- laryngoscopy
- topical anesthesia
- LMA or ETT inserted
- Ventilation with 100% FiO2 until surgeon is ready to site the rigid laryngoscope with jetting needle
- Maintenance anesthesia with propofol and remi infusion
- At end of surgery, LMA reinserted
- NDMR antagonized
- Anesthetic infusions stopped
- smooth awakening with LMA/ETT removal
14
Q
How is adequacy of jet ventilation assessed?
What are complications of jet ventilation?
A
- Assess it continuously! by:
- observation of chest movements
- O2 sats
- listening for changes to the sound during air entrainment and exhalation
- observation of airway patency
- Complications of jet ventilation:
- crepitus
- pneumothorax
- barotrauma
- gastric distension
15
Q
How are lasers used in Airway surgery?
Advantages?
What type is most common? Why?
A
- Laser light beams are used for their thermal effects to cut, coagulate, and vaporize tissues
- lasers have one wavelength, moving in the same direction and its beam is parallel
- Laser light emits a small amount of radiation
- Advantages:
- very precise
- minimal edema
- minimal bleeding
- CO2 laser is common in Airway d/t shallow depth of burn and extreme precision
- Long wavelength absorbed by surface tissues
16
Q
What are the hazards of using lasers in airway surgery?
A
- Atmospheric contamination
- plume of smoke and fine particulates
- deposition in lungs
- leads to PNA, inflammation, viral infections
- Perforation of a vessel or structure
- Embolism
- Inappropriate energy transfer
- reflection and scatter of beams can cause immediate or delayed injury to normal tissue, especially the eyes
- CO2 reacts at surface causing corneal damage
- Nd: YAG and argon gas pass through the cornea to the retina
- tape eyes closed and cover with wet gauze
- PROTECT YOUR OWN EYES!
- Fires!
- Lasers produce intense heat
- CO2 laser can penetrate ETT and ignite fire
- usually subglottic, epiglottic and orpharyngeal areas are involved in fire
- smoke inhalation
17
Q
What are the strategies used to reduce the incidence of airway fire?
A
- Reduce flammability of ETT
- remove flammable materials from the airway by using jet ventilation or intermittent extubation with or without apnea
- reduce available oxygen (best is 0.3 FiO2)
- avoid paper drapes and oil-based lubricants, caution with alcohol prep solutions
18
Q
What are anesthetic consdierations for laser airway surgery?
A
- Surgical visibility vs airway control
- GETA with laser ETT and methylene blue or NS in the cuff
- Insufflation techniques through nasal tube
- Jet ventilation thru jeting arm of scope
- apneic technique
- lowest possible FiO2
- Protect yees with laer safety eyewear or saline moistened pads and laser eye shields
- face and neck should have wet gauze over them
- have NS readily available to douse fire
37
Q
What are the different types of LeFort fractures?
A
- Transverse fx through floor of maxillary sinuses (only palate moves)
- Fracture through maxillary sinuses (pyramidal fx)
- Fracture through orbits (craniofacial dysjunction)
41
Q
Thyroidectomy:
indications
complications
A
- Removal for cancer and goiter
- Complications
- removal of parathyroid gland
- tracheal compression
- damage to laryngeal nerves
- RLN, extension of SLN
