The Airway

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The Airway Powered By Docstoc
					        The Airway


    John G. Younger, MD, MS
       Assistant Professor
Department of Emergency Medicine
            To Do List


• Functional Considerations
• Anatomical Considerations
• Essential Airway-related Illnesses
                  Your Work
                 Of Breathing
                                Your Airway
Your Minute                      Geometry
Ventilation

              Q = pDPr4
                   hL
         Viscosity of
         What You’re
          Breathing
                                       Airway Geometry:
                                       Effect of Radius
                             25
Delta P to Maintain Normal




                             20
    Minute Ventilation




                             15

                             10

                             5

                             0
                                  60    70        80          90   100
                                         % Normal Airway Radius
                                             Airway Geometry:
                                             Effect of Length
Delta P to Maintain Normal Minute




                                    30

                                    25

                                    20
           Ventilation




                                    15

                                    10

                                    5

                                    0
                                         0   1      2       3        4       5   6
                                                 Airw ay Length (x Normal)
       Role of the Airway
• Conduit for ventilation
         Role of the Airway
•   Conduit for ventilation
•   Site of vocalization
•   Conduit for food and water
•   Site of preliminary digestion
•   Important region of mucosal immunity
•   Exclusive domain of 2 of the 5 senses
•   Means of facial expression
From a respiratory perspective,
  diseases of the airway are
      diseases of radius.
                 Stridor
• The Classic Physical Finding
• Sound resulting from turbulent airflow
• Commonly described as inspiratory or
  expiratory
• To a point, phase of respiration can provide
  a clue as to the location of the airway
  narrowing
Inspiratory Stridor: The Hallmark of
  Extrathoracic Airway Compromise

   Venturi Effect
   Collapses the
   Flexible-walled
   Extrathoracic Airway




   Intrathoracic
   Airways Pulled
   Open by Lung
   Parenchyma


                          Inspiration
Expiratory Stridor: Sign of Intrathoracic
    Tracheal or Bronchial Obstruction

  Venturi Effect less
  Prominent due to
  Limitation of airflow from
  Within the chest




 Intrathoracic
 Airways Collapse
 With Falling Lung
 Volume


                               Expiration
•   External obstruction
•   Teeth
•   Tongue and Mandible
•   Tonsils
•   Epiglottis
•   Retropharyngeal
    Space
•   Soft Palate
•   Cords
•   Subglottic Trachea
 Role of the Airway in SIDS

• Extrinsic or intrinsic airway
  obstruction
• Inappropriate respiratory
  drive or arousal
• Inappropriate
  hypoxia/hypercarbia
  detection
              Ludwig’s Angina
• Odontogenic infection
   – Mixed aerobic/anaerobic
• Typically mandibular
• Floor of the mouth is
  described as ‘woody’
• Compresses airway via
  peritracheal soft-tissue
  swelling
• Surgical emergency
• Often requires
  tracheotomy
          Facial Trauma
• Maybe immediate
  threat
• Securing airway
  difficult, and
  often must be
  done at scene
• Functional
  reconstruction
  difficult
     Tonsils
• Prominent lymphoid
  tissue
• Very reactive
• Viral and bacterial
  infection common
• Hypertrophy also
  common
• Decision to remove
  based on:
   – Recurrent infection
   – Airway obstruction
   – Zeitgeist
   Epiglottitis
• Notorious H. influenzae
  B infection in children
  2-7 (mean 3.5)
• HIB vaccine has largely
  eradicated this illness
  in US
• Nevertheless, some
  classic teaching points…
  Presentation of Epiglottitis
• Onset < 1 day
• High fever
   – Often associated with
     bacteremia
• Drooling rather than
  swallowing
• Change in voice
• Restless
• Resists being
  repositioned
 Key Findings in Epiglottitis
• ‘Toxic’ Child
• X-ray findings
  – ‘Thumbprint’
  – Dilated
    hypopharynx
• ‘Cherry Red’
  Epigottis
  Management of Acute Epiglottitis


• Rapid, definitive
  control of the airway
• Typically in OR
• Intubate ‘from above’
  but be prepared for
  surgical airway.
               Croup (Laryngo-
              tracheobronchitis)
• Much more likely
  diagnosis in child with
  stridor
• Occurs in kids < 5
  years of age
• Almost always viral
• Presents with late-
  night barking cough
• Classic x-ray finding is
  ‘steeple sign’
   Retropharyngeal Abscess
• Classic complication of
  suppurative upper
  airway infection like
  Strep throat
• May occur with cervical
  osteomyelitis,
  particularly in
  intravenous drug users
• Interesting disease,
  but pretty uncommon
  Disorders of the Soft Palate:
    Obstructive Sleep Apnea
• Multiple Etiologies
   – Abnormalities of the
     soft palate
   – Obesity
      • ‘Obesity
        hypoventilation
        syndrome’
   – Any other partial airway
     obstructions
   – CNS changes in
     respiratory drive or
     pharyngeal muscle
     control
 Polysomnogram (PSG) of
Classic Obstructive Apnea
   OSA: Typical Symptoms
• Snoring
  – To the distress of sleep partners
• Excessive daytime sleepiness
  – Worst case is ‘Pickwickian’ syndrome
  – Fat Joe was a character in Dicken’s
    ‘Pickwick Papers’ who was always falling
    asleep
        OSA: Complications
•   Pulmonary hypertension
•   Congestive heart failure
•   Myocardial infarction
•   Stroke
     Treating OSA:
Change in Sleeping Position
Treating OSA:
 Palatoplasty
Treating OSA: Biphasic Positive
   Airway Pressure (BiPAP)
Disorders of the Vocal Cords
• Edema
• Paralysis
  – Stroke, peripheral
    nerve injury
• ‘Vocal Cord
  Dysfunction’
  – Spastic dysphonia
• Mass
       Subglottic Conditions
•   Tracheomalacia
•   Tracheal stenosis
•   Intratracheal mass
•   Extrinsic compression by mediastinal
    structure
    – Vascular rings
    – Adenopathy
    – Tumor
     Controlling the Airway
• Endotracheal
  intubation
  – Plastic airway placed via
    the nose or mouth
  – May require deep
    sedation (induction of
    anesthesia) and even
    neuromuscular blockade
    to successfully place
  – By necessity, ET tubes
    elongate (DL) and
    narrow (Dr4) the airway
         ‘Surgical Airways’
• Used to acutely or chronically divert
  airflow from the pharynx
  – Impaired gag or swallow
     • Neurological abnormalities
  – Threat of obstruction
     • Cancer
     • Infection
     • Trauma
  – Reduce work of breathing by reducing anatomic
    deadspace
Tracheotomy
Cricothyroidotomy
               Summary

• Regarding airflow through the upper
  airway, airway radius is the predominate
  geometric determinate
• Stridor, especially inspiratory, is a
  hallmark feature of partial upper airway
  obstruction
• Many illnesses may lead to airway
  obstruction, but the immediate therapy is
  always the same: control the airway.

				
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posted:3/18/2012
language:English
pages:42