LARYNGOSPASAM A complication of General Anesthesia, commonly ocured at recovery phase.

Laryngiospasm A complication of General Anesthesia

1. LARYNGOSPASM Ahmad Ullah Anesthesia Technologist (KMU-IPMS)

2. Laryngospasm Involuntary and forceful contraction of laryngeal muscles, which results from the depolarization of superior laryngeal nerve. (vocal cords adduction) Laryngospasm is the sudden and sustained closure of the  glottis , usually as a protective mechanism to prevent aspiration, against a noxious stimulus. 2

3. Laryngospasm Presentation • Difficult or impossible face mask ventilation • Difficult or impossible ventilation with a supraglottic airway • “Crowing” sound on inspiration 3

4. Incidence Rare but Mostly seen during anesthesia Emergence 48%, induction 28%, maintenance 24% 4

5. Pathophysiology Mechanical and chemical stimulation of airway structures leading to afferent stimulation of vagus and trigeminal nerve – activation of intrinsic adductor muscles. It is mediated by the vagus nerve; this reflex is designed to prevent foreign materials from entering the tracheobronchial tree. 5

6. MUSCLES of larynx The intrinsic  laryngeal muscles  are the main mediators of laryngospasm. These include the cricothyroid, lateral cricoarytenoids, and the thyroarytenoid muscles.  6

7. Risk factors  Unknown ....(43%) Patient-related – Young age – Anxiety – GERD – URI or active asthma (2~10 folds the risk) – Chronic smoker – Airway anomaly ,sleep apnea synd. – Unsupervised patients in recovery of anaesthesia (specially children's) 7

8. Surgery related – Throat and/or Airway surgery – Laryngeal Surgery – Thyroid surgery Tonsil's surgery SLN injury – Esophageal procedure 8

9. Anaesthesia related – Insufficient depth of anesthesia during induction or surgical stimulus – i.v. induction agents • Barbiturate • Ketamine, saliva – LMA > ETT > face mask – Airway irritation Irritant Volatile anesthetics: isoflurane Mucus or blood after extubation Residual paralysis: common cause vomiting or regurgitation 9

10. Diagnosis Harsh breathing inspiratory sound (stridor) exclude o ther causes of airway obstruction, e.g. tongue drop, bronchospasm, – fall in spo2(usually fast) Partial laryngospasm • Signs of inspiratory airway obstruction – Use of accessory muscles – Paradoxical movement of chest and abdomen 10

11. Auscultation : Inspiratory Obstruction Complete laryngospasm : absence of breath sounds Late change – Bradycardia – Cyanosis 11

12. Prevention • Identify patients at risk is the most important • Nonirritant inhalational anesthetic, e.g. sevoflurane • Deep anesthesia before intubation No surgical stimulation in light plan of anesthesia • Extubate while the lungs are inflated by positive pressure – ⇓ Adductor response of laryngeal muscle 12

13. Prevention Drugs – Premedication with oral BZD – Anticholinergics ⇓ secretion – Lignocaine Spray to larynx at 4 mg/kg (1 mL 10% lidocaine for a 25 kg pt ) 13

14. Intravenous (lignocaine) • Controversial in preventing laryngospasm Some said i.v. at 1 mg/kg 5 min before extubation fairly effective as topical use 14

15. Management (Treatment) – Identify and remove the stimulus – Apply jaw thrust maneuver – Insert oral or nasal airway – Positive pressure ventilation with 100% O2 – Anxiolysis ( assurance and sedation) – Inj. Xylocaine 1 mg/kg – Inj. Propofol 0.25-1 mg /kg – Steroids -Inj. Hydrocortisone , Dexamethasone 15

16. Complete laryngospasm – Call for help – Deepen the anesthesia level • If laryngospasm occurs without i.v. line intraosseous route 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 16

17. Intravenous: atropine and succinylcholine Intramuscular : succinylcholine (4mg/kg) vocal cords relax within one minute; last several minutes ….IPPV---Intubation 17

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19. Special Considerations • Untreated laryngospasm can rapidly lead to hypoxemia and hypercarbia . • Patients who generate high negative inspiratory pressures while attempting to breathe against the obstruction may develop negative-pressure pulmonary edema. 19

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