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Laryngospasm
R3
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Introduction A protective reflexive glottic closure
prevent aspiration
Its exaggeration impedes respiration
Self-limited mostly: prolonged hypoxia andhypercapnea abolish the reflex
If sustained, morbidity (e.g. cardiac arrest,
PE,etc.) and mortality ensue
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Epidemiology Inversely related with age
The overall incidence: 0.87%
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Anatomy
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Anatomy
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Physiology A multitude of mechanoreceptors,
chemoreceptors and thermoreceptors arethroughout the larynx
The density is greatest around the laryngeal
opening The posterior aspect of the true vocal folds has
greater density than the anterior
Stimulation of these receptors induce short-livedglottic adduction to protect from aspiration
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Mechanism Afferent fibers within the internal branch of the SLN
Spasmodic dysphonia: involuntary spasms in thelaryngeal muscles during speech production Neuroimaging(20:20) and postmortem histopathology(20:3)
Axonal and myelin content in the genu of internal capsule
Mineral depositions in parenchyma and vessel walls of the post.limb of the int. capsule, putamen, globus pallidus and cerebellum
Efferent response to the entire vagus apnea,bronchoconstriction, bradycardia, peripheral vasculartone change
There is a speculation: such a response leads to suddeninfant death, possibly in reaction to LPR
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Risk Factor Patient-related
Young age
Anxiety GERD URI or active asthma
2~10 folds the risk
Chronic smoker
Airway anomaly Surgery-related
T and/or A LMS Thyroid surgery
SLN injury Hypoparathyroidism
Esophageal procedure Distal afferent nerves
Anesthesia-related Insufficient depth of
anesthesia during induction i.v. induction agents
Barbiturate Ketamine saliva
LMA > ETT > face mask
Airway irritation Volatile anesthetics Mucus or blood after
extubation
Children supervised by lessexperienced anesthesiologist
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Prevention Identify patients at risk is the most important
Nonirritant inhalational anesthetic, e.g.sevoflurane Deep anesthesia before intubation Extubate while the lungs are inflated by positive
pressure Adductor response of laryngeal muscle Artificial cough
5% CO2 inhalation for 5 min before extubaionCO2 exhalation drive > the laryngospasmreflex Acupuncture
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Prevention Drugs
Premedication with oral BZD upperairway reflex during induction
Anticholinergics secretion
Lidocaine
Spray to larynx at 4 mg/kg (1 mL 10% lidocaine fora 25 kg pt)
30 min in duration
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Intravenous Lidocaine
Gilbert first used i.v. lidocaine as an
adjunct to general inhalation agents in1951
Controversial in preventing laryngospasm Some said i.v. at 1 mg/kg 5 min before
extubation fairly effective as topical use
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Deep versus Awake Extubation Controversial
Awake extubation
Protect the airway from aspiration
Deep extubation Less likely to cough and strain, which can
cause bleeding throat irrtation
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Treatment Partial laryngospasm
Identify and remove the stimulus
Apply jaw thrust maneuver Insert oral or nasal airway Positive pressure ventilation with 100% O2
Complete laryngospasm
Call for help Deepen the anesthesia level
If laryngospasmoccurs without i.v. line intraosseousroute offer a faster central circulation than peripheral
Lidocaine SLN block 5 mL of 2% lidocaine + 5 mL NS nebulized by 100% O2 Transtracheal injection of 1~2 mL 4% lidocaine
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Superior Laryngeal Nerve Block
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The LaryngospasmNotch
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Follow Up Assess for the possibility of developing
Pulmonary aspiration
Postobstructive negative pressure pulmonaryedema
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Paroxysmal Laryngospasm Extremely rare and is diagnosed by history:
spontaneous sudden onset of stridulousdyspnea, resolve within minutes
Frequently have a positional component, maywake the patient
Extremely distressing, impending doom
LPRmucosal hypersensitivitymaladaptedreflex arc
Aggressive elimination of LPR satisfactorilytreated the majority of patients
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Reference Head & Neck Surgery - Otolaryngology, 4th Edition ABERRANT RECURRENT LARYNGEAL NERVE REINNERVATION AS A CAUSE
OF STRIDOR AND LARYNGOSPASM Ann Otol Rhinol Laryngol 113:2004
Aerosolized Lidocaine for Relief of Extubation LaryngospasmANESTH ANALG2005;101:1563
An approach to the management of paroxysmal laryngospasm The Journal ofLaryngology & Otology ( 2008), 122, 5760.
Focal white matter changes in spasmodic dysphonia: a combined diffusion tensorimaging and neuropathological study Brain (2008), 131, 447-459
Intervention steps for treating laryngospasmin pediatric patients PediatricAnesthesia 2008 18: 297302
Laryngospasm: review of different prevention and treatment modalities PediatricAnesthesia 2008 18: 281288
Laryngospasmin pediatric practice Pediatric Anesthesia 2008 18: 279280 Risk factors for laryngospasmin children during general anesthesia Pediatric
Anesthesia 2008 18: 289296 The use of preoperative lidocaine to prevent stridor and laryngospasmafter
tonsillectomy and adenoidectomy Otolaryngol Head Neck Surg 1998;118:880-2. Transtracheal lignocaine: effective treatment for postextubation stridor Anesth
Intensive Care 2007; 35:128-131
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