Case 44 - Laser laryngoscopy Flashcards
A singer who underwent surgery now experiences post-operative hoarsness for the past week. What are casues?
1) Anatomic disruptions
- vocal fold tear
- intubation granuloma
- arytenoid disolocation
- vocal fold edema
- prolong intubation causing laryngeal stenosis
2) neuromotor injury
- high riding ett cuff cuaing recurrent laryngeal nerve compression
- vocal cord paralysis
how is airway pathology evaluated prior to surgery?
1) history/physical
- inspiratory stridor - suggest airway stenosis approx 4mm in diameter
- absence does not always indicate normal sized airway
- exhausted/fatigue 2/2 inability to generate enough airflow passed a stenosis
- hoarseness (although non-specific)
- dysphagia –> suggests supraglottic obstruction
- inability to lie flat, need to sit upright, frequent position changes to breathe –> indicate severe airway obstruction
2) studies
- supraglottic and glottic masses –> nasopharyngoscopy
- subglottic and tracheal masses –> CT, MRI
explain special anesthesia requirements for laryngeal surgery
1) airway shared between sx and anesthesiologist
- anesthesia –> need to minimize as much space as possible in airway for surgical view and instrumentation
- small ETT or jet ventilation
2) surgical stimulation
- profound stimulation during surgery –> deep anesthesia
- minimal stimulation at end of surgery –> need to reverse deep anesthesia for emergence and extubation
3) emergence/extubation
- smooth emergence, avoid coughing/bucking
- can lead to hemorrhage and suture disruption
-
airway surgery assoc with highest risk of postextubation airway compromise
- swelling, bleeding
- awake extubation, strong muscle tone for airway dilator muscles to maintain upper airway patency
What are anesthetic considerations for laryngeal microsurgery ?
General Considerations
1) operating room table turned 90 to 180 degree
- expandable breathing circuit
- adequate length of monitoring cables
2) small ETT (MLT tubes like 5.5 mm ID)
- provides adequate surgical visualization
- may be able to advance passed subglottic lesions
3) ventilation
- MLT tube require higher peak pressure to maintain minute ventilation
- change I:E ratio form 1:2 to 1:1 to allow greater insp time
- consider jet ventilation
4) blunt sympathetic stimulation
- deep plane of aneshtesia
- opioids (rapid on/off like remifentanil)
- beta blockers
what are options for vocal cord immobility?
- intermediate acting muscle relaxants
- avoid loading dose since surgery is relatively quick
- neuromuscular monitoring for antagonism
- opioids
- remifentail (fast on and off)
- deep plane of anesthsia
How would you emerge patient from anesthesia after airway surgery?
- avoid coughing or straining
- disrupt surgical sutures, inc bleeding
- awake vs deep emergence
- awake emergence allows assessment of one’s ability to maintain upper airway muscle tone
- deep extubation avoids coughing but high risk of aspiration of blood and debris 2/2 airway surgery
- consider waking patient up on remifentanil infusion with ETT in place
- ask surgeon to directly topicalize airway
if patient has tracheomalacia or laryngeal lesions, affect your anesthesia management?
1) airway dynamics (ex: tracheomalacia)
- maintain spont ventilation for diagnostic purposes
- inhalation induction with sevo and 100% oxygen
- with deep anesthsia, laryngoscopy to view trachea during insp and exp
2) Layrngeal Lesions (ex: vocal cord polyps/papillomas)
- less obstruction with PPV
- potentially difficult to mask or ventilate with SGA
- anesthesia is worse in anestheisized spont breathing pts than in anesthesized pts with PPV
- spont breathing –> negative intrathoracic pressure that transmits to upper airway and draws pharyngeal tissue into airway.
- no problem if awake (pharyngeal dilator muscles contract and maintain patency)
- under general anesthesia, lose dilator muscle contraction, unopposed pharyngeal tissue into airway = obstruciton
- PPV stents airway open
if patient has subglottic lesion, how does this affect your anesthesia management?
subglottic lesion
- difficult to pass ett, may require MLT
- consider supraglottic jet ventilation
What are the advantages and disadvantages of a closed system ventilatory techinque for larygneal surgery?
- decision to choose open vs closed system ventiliatory technique depends on location, size, mobility, and vascularity of the lesion
- you can always convert from one to another if need be
Closed system - Advant
- familiar to anesthesologists
- protection against aspiration
- PPV
- minimal OR pollutoin
Disadvant
- limits surgical visibility
- interfere with surgical manipulation
- risk ETT-related laryngeal damage
- risk of fire during laser surgery
What are advantages and disadvantages of open system ventiliatory technique for airway surgery?
Open Technique:
- spontaneous ventilation, apneic oxygenation, jet ventilation
Advant
- maximal surgical visibility
- maximum surgical manipulation
- decrease risk of ETT-related trachael trauma
- decrease risk of fire during laser surgery
disadvant
- requires special knowledge, training, equpiment
- no aspiration protection (gastric, blood, debri from surgery)
- cannot provide PVV
You choose to do spontaneous ventilation for airway surger, how do you do this?
- spont ventilation is achieved with either
- 1) potent inhaled anesthetic via facemask, nasopharyngeal airway, or laryngosocpe/bronchoscope side port
- 2) TIVA
Disadvant
- with potent inhaled anes - OR pollution, coughing, bucking, apnea, laryngospasm, vocal cord movement, BP fluctuations, inability to protect against aspiration
What is apneic oxygenation?
- provide patient oxygenation with facemask or temporary placement of ETT –> 100% oxygen to reach ETo2 > 90%.
- after, render patietn apenic, at which point surgical manipulation occurs
- once SaO2 < 90%, halt surgery, and begin oxygenating again to increase SaO2.
- Repeat
- anesthesia maintained with TIVA, or inhaled anes, or both,
How does jet ventilation work?
Jet ventilation
- admin 100% oxygen under 20 psi via catheter or blunt needle
- administer TIVA (cannot use inhaled anes)
- supraglottic (proximal) jet ventilation vs subglottic jet ventilation
Supraglottic
- jet needle attached to suspension laryngoscope or rigid bronchoscope (aimed at larynx)
- advant
- unobstructed surgical view,
- limit risk of airway fire (dilute delivered oxygen with room air 2/2 venturi principle = room air entrainment)
- disadvant
- poor oxygenation, gastic insufflation, aspiration of blood, smoke, debris, barotrauma
- vocal cord mobility (due to air flow)
Subglottic
- jet ventilation catheter into trachea, o2 delivered directly into trachea
- airflow directed beyond vocal cord, therefore vocal cord immobility
- disadvant: obstruction of surgical field, barotrauma
you provide jet ventilation for airway surgery, however you are unable to increase SaO2, and breath sounds are diminished on the right side. You suspect pneumothorax, how is this possible?
Jet Ventilatoin
- oxygenate via jet ventilator catheter directed at the trachea
Ventilation
- passive
- require airway patency for air entrainment and gas egress
- upper airway obstruction does not allow gas form lungs to escape –> pneumothorax or pneumomediastinum
- ensure upper airway patency with jaw thrust, chin lift, placement of laryngscope (suspension)
is quantative measurement of ETco2 important or feasible during open system ventilatory technique?
- due to room air entrainment delivering large volume of gas to the lungs with jet ventilation, you will have dilution of ETCo2 and the quantative number will not be accurate
- qualitative measurement of ETCo2, chest wall undulations and breath sounds are clinical evidence of ventilatoin
