Emergency Care and Transportation of the Sick and Injured: Airway Management

CHAPTER 11: Airway Management

Introduction

  • Primary component of caring for patients is ensuring that they can breathe adequately.

  • Disruption of the ability to breathe compromises oxygen delivery to tissues and cells.

  • Oxygen reaches body tissues and cells through breathing and circulation.

Anatomy of the Respiratory System

  • The respiratory system consists of all the structures that make up the airway and help in breathing (ventilation).

  • The airway is divided into the upper and lower airways.

Anatomy of the Upper Airway

  • Components:

    • Nose

    • Mouth

    • Oral cavity

    • Pharynx

    • Larynx

  • Main Function: The upper airway warms, filters, and humidifies air as it enters the body.

Pharynx

  • Muscular tube that extends from the nose and mouth to the level of the esophagus and trachea.

  • Parts:

    • Nasopharynx

    • Oropharynx

    • Laryngopharynx

Nasopharynx

  • Filters out dust and small particles.

  • Warms and humidifies air as it enters the body.

Oropharynx

  • Description: The posterior portion of the oral cavity.

  • The epiglottis is superior to the larynx.

Larynx

  • Complex structure formed by many independent cartilaginous structures.

  • Marks the endpoint of the upper airway and the beginning of the lower airway.

  • Key Structures:

    • Thyroid cartilage: forms a “V” shape anteriorly.

    • Cricoid cartilage: first ring of the trachea.

    • Glottis: area between the vocal cords.

Anatomy of the Lower Airway

  • Function: Deliver oxygen to the alveoli; includes:

    • Trachea

    • Bronchi

    • Lungs

Trachea

  • Conduit for air entry into the lungs.

  • Divides at the carina into two main stem bronchi, right and left, which are supported by cartilage to distribute oxygen to the lungs.

Bronchioles and Alveoli

  • Bronchioles are made of smooth muscle and connect to alveoli.

  • Oxygen is transported back to the heart from the alveoli for distribution.

  • Transport Mechanism: Oxygen is sent via the circulatory system to the rest of the body.

Thoracic Cavity

  • Contains important structures for ventilation, oxygenation, and respiration:

    • Lungs

    • Bronchi

    • Heart

    • Great vessels (the vena cava and aorta)

    • Trachea

Ventilation Mechanism

  • Illustrated by bell jar mechanism demonstrating inhalation and chest expansion.

Physiology of Breathing

  • The respiratory and cardiovascular systems work in tandem to ensure oxygen and nutrients are delivered to cells and waste products are removed.

Difference between Oxygenation and Ventilation

  • Oxygenation:

    • Measured with Pulse Oximetry (normal range 94-99%).

  • Ventilation:

    • Measured with Capnography (normal range 35-45 mmHg).

Ventilation

  • Definition: Physical act of moving air into and out of the lungs.

  • Inhalation:

    • Active, muscular part of breathing involving contraction of the diaphragm and intercostal muscles.

    • Creates a negative pressure in the thorax, allowing air to enter.

    • Necessitates chest movement for lung expansion.

Concepts:

  • Partial Pressure: The amount of gas in or the air or dissolved in fluid (blood).

  • Oxygen and carbon dioxide diffuse until partial pressures are equal in air and blood.

Tidal Volume and Dead Space

  • Tidal Volume: Average of 500 mL in adults.

  • Dead Space: Portion of air that does not reach the alveoli.

Exhalation

  • Normally a passive process that does not require muscular force, relaxing diaphragm and intercostal muscles to compress air within the lungs.

Regulation of Ventilation

  • Involves complex receptors and feedback loops.

  • Failure to meet oxygen needs can result in hypoxia, often regulated by changes in pH of blood and cerebrospinal fluid.

  • Hypoxic Drive: Recognized in patients with end-stage COPD.

Oxygenation

  • Process: Loading of oxygen molecules onto hemoglobin in the bloodstream is critical for internal respiration, but does not guarantee it is occurring.

Respiration

  • Definition: Exchange of oxygen and carbon dioxide in alveoli and body tissues.

  • Types of Respiration:

    • External Respiration (Pulmonary Respiration):

    • Fresh air enters the respiratory system, facilitating gas exchange between alveoli and pulmonary capillaries.

    • Internal Respiration:

    • Exchange of gases between systemic circulatory system and cells.

Pathophysiology of Respiration

  • Nervous System Factors: The nervous system uses chemoreceptors to monitor levels of oxygen, carbon dioxide, hydrogen ions, and pH in cerebrospinal fluid, feeding back to respiratory centers.

Ventilation/Perfusion Mismatch

  • Must ensure air and blood flow to coincide.

  • Mismatched ventilation and perfusion results in inadequate gas exchange leading to severe hypoxemia.

Factors Affecting Pulmonary Ventilation

  • Intrinsic Factors:

    • Infections

    • Allergic reactions

    • Unresponsiveness (e.g., tongue obstruction)

  • Extrinsic Factors:

    • Trauma, including tension or simple pneumothorax, open pneumothorax, hemothorax, hemopneumothorax.

Circulatory Compromise

  • Trauma and airway obstructions can lead to reduced blood flow, increasing risk of hypoxia.

    • Causes include blood loss, anemia, or types of shock (hypovolemic, vasodilatory).

Patient Assessment

  • Aerosol-generating procedures (AGPs): include CPR, nebulizer treatments, endotracheal intubation, and CPAP.

Recognizing Adequate Breathing

  • Between 12 and 20 breaths/min, regular inhalation/exhalation patterns, bilateral clear and equal lung sounds, and adequate depth of breathing (tidal volume).

Recognizing Abnormal Breathing

  • Fewer than 12 or more than 20 breaths/min, irregular rhythm, diminished auscultated breath sounds, or cyanosis.

  • Increased effort of breathing and abnormal skin conditions may signal inadequate breathing.

Additional Signs of Inadequate Breathing

  • Agonal gasps may appear when the heart stops; recognizing Cheyne-Stokes respirations in patients with strokes or head injuries is critical.

Ataxic and Kussmaul Respirations

  • Ataxic: Irregular or unpredictable pattern often following serious head injuries.

  • Kussmaul: Deep, rapid respirations commonly seen in metabolic acidosis.

Airway Opening Techniques

  • Emergency care begins with ensuring an open airway, particularly for unconscious patients. The supine position is most effective for assessment.

  • The tongue is identified as the most common airway obstruction in an unconscious state.

Head Tilt–Chin Lift Maneuver

  • Effective method to open the airway in non-traumatized patients. Steps include:

    1. Position beside the patient’s head.

    2. Apply firm backward pressure on the forehead.

    3. Lift the chin with the other hand.

Jaw-Thrust Maneuver

  • Recommended if cervical spine injury is suspected; uses upward force on the lower jaw.

Mouth Opening Techniques

  • Use the cross-finger technique when the mouth is closed to achieve airway access.

Suctioning Techniques

  • Essential to keep the airway clear and enable proper ventilation.

  • Suction equipment should be portable, with compatible tubing and suction tips.

  • Frequency and duration of suctioning depend on patient demographics (e.g., adult vs. children).

  • Care should be exercised not to activate the gag reflex or over-suction.

Airway Adjuncts

  • Oropharyngeal Airways:

    • Prevent tongue obstruction and facilitate suctioning; used in unresponsive patients without a gag reflex.

    • Contraindicated in conscious patients with an intact gag reflex.

  • Nasopharyngeal Airways:

    • Used in patients who are unresponsive or have impaired levels of consciousness but possess a gag reflex.

    • Contraindicated in patients with severe head trauma or facial abnormalities.

Maintaining the Airway

  • Utilize the recovery position to maintain a clear airway in conscious patients who are breathing normally.

Supplemental Oxygen

  • Always administer to hypoxic patients. Safety and handling of oxygen equipment is critical.

Oxygen Delivery Systems

  • Nonrebreathing Masks: Provide high oxygen concentration to adequately breathing patients suspected of hypoxia.

  • Nasal Cannulas: Deliver moderate oxygen concentration; effective for patients with mild hypoxemia.

Tracheostomy Considerations

  • Mask or adjunct method needed to ventilate patients with tracheostomy; improvisation may be necessary in emergency situations.

Assisted and Artificial Ventilation

  • Indicated when basic airway techniques are ineffective; one breath every 6 seconds is standard.

Signs of Inadequate Ventilation

  • Altered mental status, inadequate minute volume, excessive accessory muscle use.

Techniques for Bag-Mask Ventilation

  • Proper positioning, explaining the procedure, and ensuring adequate tidal volume are paramount.

Continuous Positive Airway Pressure (CPAP)

  • Noninvasive ventilation technique for patients in respiratory distress;

    • Utilizes back pressure to keep airways open and improve oxygenation.

CPAP Indications and Contraindications

  • Useful for alert patients exhibiting significant respiratory distress but contraindicated in certain conditions, such as respiratory arrest or significant trauma.

Airway Obstruction Management

  • Complete obstruction is a life-threatening scenario that requires immediate action, often seen in adults during meals and in children with small toys.

Understanding Obstruction Types

  • Mild: Patients can exchange air but may exhibit respiratory distress. Treatment involves allowing the patient to expel the object if able.

  • Severe: Patients cannot breathe, talk, or cough. Recognizable signs include cyanosis and distress.

Foreign Body Management

  • Uses modifications of clearance techniques, including abdominal thrusts to dislodge foreign bodies.

Dental Appliances and Facial Bleeding

  • Awareness of how dental appliances can interfere with ventilation and management of facial trauma is critical for maintaining airway patency.

  • Control any significant facial bleeding impacting the airway.

Assisting with ALS Airway Procedures

  • Incorporate advanced techniques and equipment setup for effective airway management for patients requiring more than basic interventions.

Review Questions

  • Breathing control mechanisms identified with responses contextualizing anatomy related to respiratory functionality.

    • E.g., control centers in the brainstem manage normal ventilation cycles via feedback from various blood gas levels.

  • Additional queries assessing conditions and identifying case-specific ventilation techniques.