Download Microlaryngeal surgery

Anesthesia for
Microlaryngeal Surgery
By
Dr. Karim Youssef Kamal Hakim,M.D.
Lecturer of Anesthesia and Intensive Care
Faculty of Medicine
Ain Shams University
Micro-laryngoscopy definition:
It is surgery in larynx by laryngoscope aided by an
operating microscope.
Inflammatory laryngeal
polyp:
Anesthetic problems:
• Patients with upper airway problems.
• It is usually done as an outpatient
procedure.
• Profound muscle relaxation is needed.
• Oxygenation and ventilation.
• CVS instability.
• Postoperative spasm or edema.
Preoperative Management:
Careful preoperative assessment for airway
problems e.g. obstructing tumors, vocal cord
polyps.
• By history, examination and investigations as CT
scan or MRI.
• All equipment for difficult intubation should
available preoperatively.
Premedication:
• Sedatives are avoided if any degree of airway
obstruction is suspected.
• Anticholinergics are used to decrease secretions
and avoid bradycardia.
Intra-operative Management:
It may be an outpatient procedure so consider its
precautions.
1. Profound muscle relaxation:
•
It is done usually by short acting nondepolarizing muscle relaxants ( as it is usually a
short procedure).
•
In children, spontaneous ventilation without
muscle relaxant may be used.
2 . Oxygenation and Ventilation:
1.
•
Micro-Laryngeal tracheal tube or
Mallinckrodt Critical Care Tube:
It is the most commonly used. It can be used orally or
nasaly.
•
It is 4,5 or 6 mm I.D., but with the same adult length (31
cm) and with a large high volume low pressure cuff ( filled
with 10 ml ) and is stiffer ( less prone to compression).
Advantages:
•
Its small size will not impede the surgeon´s view.
•
Its cuff will prevent aspiration of blood or debris.
•
It allows introduction of inhalational agents
•
It allows monitoring of ET CO2.
2. Conventional E.T.T. of small size:
•
•
Use one size smaller in children.
Use size 4, 5 or 6 mm I.D in adults.
•
•
It is too short for the adult trachea.
It is with low volume cuff that will exert high
pressure against the trachea.
Disadvantages:
3. Pollards Tracheal Tube:
•
•
It is formed latex reinforced with nylon spiral.
Its proximal end size is 10 mm ID and distal end
size is 5-7 mm ID.
IN (1),(2),(3):
Induction: Short acting opioids +thiopentone + suxamethonium or
short acting non-depolarizing muscle relaxant + spraying the
vocal cord with 3 ml lidocaine to assist smooth anesthesia.
Maintenance: O2 and NO2 + volatile agents + controlled ventilation
4. Insufflation of high flow O2 :
Via a small catheter placed in the trachea. Patients
breath spontaneously.
5. Intermittent- Apnea technique:
• The ventilation and anesthesia are maintained with
O2 and a potent volatile agent by a face mask or
E.T.T. for periods which alternate with periods of
apnea during which the surgery is performed,
usually 2-3 min.
• Pulse-oximeter is essential.
• There is risk of hypoventilation and aspiration.
Advantages:
 Immobile unobstructed surgical field.
 Safety use of laser surgery.
Disadvantages:




Risk of aspiration of blood and debris.
Variable levels of anesthesia.
Interruption to surgery for reintubation.
Potential trauma through repeated intubation.
6. Manual jet ventilation:
• It is connected to a side port of the laryngoscope.
• During inspiration ( 1-2 sec ), the jet pressure increases
gradually, starting with;
15-20 psig in adults.
5-10 psig in infants and children.
(psig = pound square inch gram)
Then increase the pressure gradually until adequate chest rise
and fall is noted.
While the O2 source is directed through the glottic opening , it
entrains room air into the lung ( venturi effect ) .
• Expiration is allowed passively in ( 4-6 seconds ).
• It is important to monitor the chest wall motion constantly
for proper tidal volume assessment and to allow sufficient
time for exhalation to avoid air trapping.
Low Frequency Jet
Ventilation
Complications:
1. Air trapping and barotrauma resulting in
pneumothorax, pneumo-mediastinum or
subcutaneous emphysema.
2. Gastric dilatation with possible regurgitation.
3. Drying of mucosal surface.
4. Aspiration of resected material.
5. Complete respiratory obstruction.
Contraindications:
1. Airway obstruction without tracheostomy.
2. Obesity.
3. Increased risk of aspiration.
4. Advanced COPD patients.
5. It is not suitable for removal of foreign body.
7. High-Frequency jet technique:
• It is a variation of manual jet ventilation.
• It utilizes a small cannula or tube in the trachea
through which gas is injected at 80-300 times per
minute.
( IN 6,7 ) TIVA is needed for induction and maintainance.
Supraglottic jet ventilation
Disadvantages
 Risk of barotrauma .
 Gastric distension.
 Misalignment of the rigid suspension laryngoscope
resulting in poor ventilation.
 Blowing of blood and debris into the distal trachea.
 Inability to monitor end tidal CO2.
Subglottic jet ventilation
Advantages:
 Reduced peak airway pressure.
 No vocal cord motion.
 Good surgical field.
Disadvantages:
Greater risk of barotrauma.
Transtracheal jet ventilation
Disadvantages:
 Barotrauma,
blockage, kinking
infection, bleeding,
failure to site the
catheter.
External high frequency oscillation
3. Cardiovascular instability:
ABP and HR fluctuate markedly during laryngoscopy and may
need invasive ABP monitoring because:
• Many patients are heavy smokers or alcohol drinkers which
predisposes them to CVS disease.
• The procedure resembles a series of stress-filled
laryngoscopies and intubations separated by varying periods
of minimal surgical stimulation.
So, maintain stable CV system by :
• Supplementation with short acting anesthetics e.g. propofol
or sympathetic antagonist e.g. esmolol ( during periods of
stimulation).
• Regional laryngeal nerve block e.g.
Glosso-pharyngeal nerve ( at the posterior tonsillar pillar).
• Topical anesthesia of the larynx with spraying lidocaine.
Postoperative Management:
• Laryngeal edema can occur in the early
postoperative period, and it is usually manifested
by retractions and respiratory stridor in the
recovery room.
• Laryngospasm can develop because of laryngeal
hyperactivity. If it happens , it is treated with
positive pressure mask ventilation with 100% O2.
More severe cases of laryngospasm may require the
use of a small, subapneic dose of succinylcholine (
0.1 to 0.2 mg/Kg IV ).
• Pneumothorax should be considered after all cases
involving jet ventilation.
• Pulmonary complications as a result of retained
secretions and subsequent atelectasis have been
reported.
Questions
1.
Day case surgery is appropriate for:
c.
d.
ASA п patients.
Accompanied patients who do not have a
telephone.
a.
b.
Operations lasting up to 3 hours.
Babies < 6 months.
2. All of the following drugs used as a
premedication except:
a.
b.
c.
d.
Atropine.
Metoclopramide.
Corticosteroids.
Diazepam.
3. One of the following drugs is used as
muscle relaxant:
a.
b.
c.
d.
succinylcholine.
Pipecuronium.
Pancuronium.
Doxacurium.
4. All of the following are contraindications
for manual jet ventilation except:
•
•
•
•
Obesity.
COPD.
Vocal cord polyp.
Patient is not fasting.
5. One of the following drugs is not used in
microlaryngeal surgery in adults:
a.
b.
c.
d.
Esmolol.
Propofol.
Ketamine.
Atracurium.
a.
b.
c.
d.
Laryngeal edema.
Laryngeal spasm.
Pneumothorax.
Pulmonary embolism.
6. Complications that may occur in postoperative period after vocal cord tumour
biopsy are all of the following except:
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