Anatomy and Physiology Review

• Upper and lower airway

• Alveoli and pulmonary capillaries

Key Concepts: Respiratory Physiology

• Perfusion: Adequate blood flow to the body cells that allows the proper delivery of oxygen and nutrients and the adequate removal of waste products

- Oxygen is transported on the red blood cell by the hemoglobin molecule

Minute volume: Tidal volume × Rate

• Alveolar ventilation: The amount of air that reaches the alveoli during ventilation

• External respiration: The exchange of oxygen and carbon dioxide from air to blood at the level of the alveoli

- Requires adequate alveolar ventilation

- Requires adequate blood flow to pulmonary capillaries

• Internal respiration: The exchange of oxygen and carbon dioxide from blood to the cells of the body

- Requires adequate external respiration

- Requires adequate blood flow to the cells (perfusion)

Pathophysiology of the Airway

• Upper airway obstruction

- Mental status: Decreasing mental status can cause structures of the airway (such as the tongue and epiglottis) to relax and obstruct air flow. Remember, this is a dynamic condition that can change rapidly.

- Foreign body airway obstruction from liquids (such as blood, vomit) and/or objects (foreign bodies, as in choking)

- Swelling of airway structures, as in anaphylaxis or trauma

• Disruption of alveolar ventilation

- Obstruction of air flow in the lower airways—example: bronchoconstriction

- Changes in the alveoli and small airways—example: pulmonary edema

• Inadequate breathing

- Rate problems leading to inadequate minute volume—example: very slow breathing as with narcotic overdose

- Volume problems leading to inadequate breathing—example: collapsed lung (pneumothorax)

• Disordered control of breathing

- Conditions such as seizures or brain injury that challenge the ability to keep an airway open or maintain adequate breathing

• Respiratory decompensation after prolonged compensation for a respiratory challenge

- Failure of the muscles of respiration as increased demand and overall respiratory challenge outpace the ability to supply oxygen to them

- Exhaustion

Recognizing Airway Problems

• Airway trauma

• Obvious airway obstruction (foreign bodies or liquid)

• Altered mental status

- Can cause airway failure

- Can be caused by hypoxia and high levels of carbon dioxide (consider a broad spectrum of mental status changes, from agitation/anxiety to lethargy and unconsciousness)

• Dyspnea and respiratory distress

• Inability to speak/move air

• Hoarse or raspy voice

• Accessory muscle use

• Stridor: the sound of restricted air movement in the upper airway

• Cyanosis

• Signs of compensation: tachypnea, tachycardia

• Lung sounds

- The sounds of diminished air movement

- The sound of no air movement (silent chest)

- Adventitious sounds: stridor, wheezing, rales and rhonchi

• Pulse oximetry less than 94%

• Capnography: increased exhaled carbon dioxide (readings greater than 45 mmHg)

Key Airway Interventions: Opening the Airway

• Head-tilt, chin-lift: Create the “sniffing” position

- Beware excessive neck movement in trauma

• Jaw-thrust: Move mandible forward to adjust soft tissues of the airway and clear the pathway for air

- Used for trauma patients

• Oral pharyngeal airways

- Used to maintain an airway

- Indicated in unconscious patients without gag reflex (beware stimulating gag reflex on insertion—have suction ready)

- Measure from corner of mouth to earlobe

- In adults, insert upside down and rotate 180 degrees following natural curvature of the airway

- In pediatric patients, insert following the natural curvature of the airway (rotation is unnecessary)

• Nasal pharyngeal airways

- Used to maintain an airway

- Indicated in situations where oral airways are contraindicated—can be used on patients who have intact gag reflex (although may still cause gag reflex)

- Use caution in patients with head/facial trauma and possible basilar skull fractures

- Measure from tip of the nose to earlobe

- Lubrication is necessary

- Insert in a backwards/downward direction using gentle twisting motion to pass nasal turbinates; DO NOT force insertion

Key Airway Interventions: Clearing the Airway

• In situations of obstruction by a liquid (blood/vomit), use position to clear the airway—roll patient onto side, allowing gravity to aid removal (always consider the need for spinal motion restriction)

- The recovery position (patient in lateral recumbent position) is designed to prevent obstruction

• Portable Suction (can be mechanical or manual) and Onboard Suction (uses power from ambulance)

- Beware power failures and have a manual backup

- Must be capable of generating 300 mmHg pressure when occluded

• Suction catheters

- Rigid (Yankauer)

 Insert only as far as is visible

 Avoid posterior hypopharynx—can cause bradycardia and decreased blood pressure

- Soft (French)

 Used when rigid tip is inappropriate

 Insert only as far as is visible

 Avoid posterior hypopharynx—can cause bradycardia and decreased blood pressure

Important Concepts: Airway Care

• Recognition of an airway problem is a critical concept that anchors the primary assessment. Always look for signs and symptoms (both dramatic and subtle) of airway problems.

• Remember that airway problems are dynamic and often develop over time. A patent airway now is no guarantee that it will remain patent.

• Airway problems often will require advanced capabilities to resolve. Consider the early activation of ALS and rapid transport to an appropriate destination hospital.