Airway Care, Oxygen Therapy Devices, Endotracheal & Tracheostomy Suctioning

Maintaining a patent airway and ensuring adequate tissue oxygenation represent paramount life-support responsibilities. The clinical nurse must expertly select oxygen delivery devices, titrate fractional inspired oxygen (FiO2), execute sterile artificial airway suctioning, and manage tracheostomy emergencies.

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1. Oxygen Therapy Devices & Fractional Inspired Oxygen (FiO2)

Oxygen is a therapeutic gas prescribed for hypoxemia (PaO2 < 60 mmHg or SpO2 < 90% in acute illness). Normal atmospheric room air consists of 21% oxygen (FiO2 0.21) and 78% nitrogen.

Low-Flow vs. High-Flow Systems

• Low-Flow Systems: Provide supplemental oxygen at flow rates lower than the patient's peak inspiratory demand (typically 20 to 30 L/min). As a result, inspired gas is diluted with ambient room air, causing the delivered FiO2 to vary with the patient's respiratory rate, tidal volume, and inspiratory flow rate.
• High-Flow Systems: Provide total inspiratory flow rates that exceed the patient's peak inspiratory flow, delivering a fixed, exact, and predictable FiO2 independent of the patient's breathing pattern.

The Venturi Mask & The Hypoxic Drive in COPD

In healthy individuals, the primary chemical trigger for ventilation is an elevated arterial partial pressure of carbon dioxide (hypercapnic drive sensed by central medullary chemoreceptors). In clients with severe Chronic Obstructive Pulmonary Disease (COPD) and chronic carbon dioxide retention, central chemoreceptors become desensitized to persistent hypercapnia.

These patients transition to relying on their hypoxic drive, mediated by peripheral chemoreceptors in the carotid and aortic bodies sensing arterial hypoxemia (low PaO2). If high-flow, uncontrolled oxygen is administered, arterial PaO2 surges, abruptly extinguishing the peripheral hypoxic drive. This results in acute hypoventilation, catastrophic CO2 narcosis, respiratory acidosis, coma, and respiratory arrest. The Venturi mask is specifically indicated because its calibrated adapters deliver an exact, controlled, low FiO2 (e.g., 24% or 28%), correcting life-threatening hypoxemia (targeting SpO2 88%–92%) without abolishing the hypoxic respiratory drive.

Oxygen Toxicity & Complications

• Oxygen Toxicity: Results from prolonged exposure to high concentrations of oxygen (FiO2 > 50% to 60% for > 24 to 48 hours). Excess oxygen generates high concentrations of reactive oxygen species (free oxygen radicals) that overwhelm endogenous antioxidant enzymes, damaging pulmonary capillary endothelium and alveolar membranes. Clinical manifestations include substernal chest ache, non-productive cough, burning on inspiration, dyspnea, paresthesias, nausea, and diffuse alveolar infiltrates.
• Absorption Atelectasis: High concentrations of supplemental oxygen wash out atmospheric nitrogen from the alveoli. Because nitrogen is an insoluble gas that acts as an anatomical "scaffold" keeping alveoli stented open, nitrogen washout causes rapid oxygen absorption into pulmonary capillaries, precipitating widespread alveolar collapse (atelectasis).

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2. Endotracheal and Tracheostomy Care & Sterile Suctioning

Artificial airways bypass the protective upper airway humidification, filtering, and warming mechanisms, making meticulous suctioning and cuff management life-critical.

Indications for Airway Suctioning

Suctioning is an invasive procedure that carries significant physiological hazards (hypoxia, cardiac dysrhythmias, bronchospasm, mucosal trauma). Consequently, suctioning must NEVER be performed on a routine, predetermined fixed schedule. It is executed strictly when clinical assessment reveals clear indications of accumulated secretions:

• Audible coarse crackles, rhonchi, or gurgling sounds over large central airways.
• Restlessness, agitation, sudden anxiety, or unexplained tachypnea.
• Deterioration in arterial oxygen saturation (sudden drop in SpO2).
• Visible secretions pooling within the artificial airway tube.
• Increased peak inspiratory pressure (PIP) alarms on mechanical ventilators.
• Ineffective, suppressed, or weak coughing efforts by the client.

Suction Pressure Settings & Catheter Sizing Rules

• Vacuum Pressure Regulators:
  • Adults: 100 to 120 mmHg (maximum 150 mmHg for extremely thick, tenacious mucus; higher pressures cause mucosal stripping and atelectasis).
  • Children: 80 to 100 mmHg.
  • Infants / Neonates: 60 to 80 mmHg.
• Catheter Sizing Rule: The external diameter of the suction catheter must not exceed half (50%) of the internal diameter of the artificial airway tube. Occluding more than half the tube creates extreme negative intratracheal pressure, resulting in massive alveolar collapse and severe hypoxia.
  • Formula: $\text{Catheter Size (Fr)} = (\text{Internal Diameter of Tube in mm} - 2) \times 2$
  • Clinical Example: For an 8.0 mm internal diameter endotracheal tube: $(8 - 2) \times 2 = 12\text{ Fr}$ (a 12 Fr catheter is appropriate; 14 Fr would occupy more than half the lumen).

Step-by-Step Sterile Suctioning Procedure

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3. Tracheostomy Tube Anatomy, Cuff Pressures & Emergency Decannulation

A tracheostomy is a surgically created opening (stoma) in the anterior trachea (typically between the second and third cartilaginous rings).

Tracheostomy Components

• Outer Cannula: The structural conduit maintaining stoma patency. Fastened to the neck via tracheostomy ties.
• Faceplate (Flange): Rests against the neck, securing the tube and displaying size markings (internal and outer diameters).
• Inner Cannula: Fits inside the outer cannula; can be unlocked and removed for regular cleaning (reusable) or discarded and replaced (disposable) to clear encrusted mucus plugs without decannulating the patient.
• Obturator: A bullet-shaped, blunt guide placed inside the outer cannula during insertion to smooth passage through tracheal tissue without laceration.
  • CRITICAL SAFETY RULE: The obturator must be taped in a clear plastic sleeve directly at the patient's bedside (at the head of the bed) at all times. In the event of accidental decannulation, the obturator is immediately required for emergency reinsertion.
• Inflatable Cuff & Pilot Balloon: A low-pressure, high-volume balloon sealing the space between the tube and tracheal wall, facilitating positive-pressure ventilation and protecting the lungs against gross aspiration.

Cuff Pressure Monitoring Standards

• Target Pressure Range: Tracheostomy and endotracheal tube cuff pressures must be maintained between 20 and 30 cmH2O (about 15 to 22 mmHg); many units aim for about 25 cmH2O.
• Monitoring Method: Measured objectively at least every 8 to 12 hours using a calibrated handheld cuff pressure manometer.
• Complications of Pressure Deviations:
  • Excessive Pressure (> 30 cmH2O / > 22 mmHg): Exceeds the capillary perfusion pressure of the tracheal mucosa, causing microvascular ischemia, mucosal ulceration, necrosis, tracheomalacia (cartilage destruction), tracheal stenosis, and fatal tracheoesophageal fistula.
  • Insufficient Pressure (< 20 cmH2O / < 15 mmHg): Fails to create an effective seal, leading to tidal volume loss during mechanical ventilation and microaspiration of contaminated subglottic secretions into the lower lungs, precipitating Ventilator-Associated Pneumonia (VAP).

Accidental Decannulation Protocol

• Decannulation within First 72 Hours (Immature Stoma): The surgical tract has not matured and can collapse immediately upon tube dislodgement. Attempting blind reinsertion risks pushing the tube into the pretracheal fascia or superior mediastinum (creating a fatal false tract with total airway obstruction).
  • Emergency Action: Call for emergency help immediately. Maintain airway patency by gently inserting a sterile tracheal dilator or hemostat into the stoma. Position patient in semi-Fowler's position, and ventilate the client using a bag-valve-mask (BVM) over the nose and mouth while holding the stoma closed with a gloved hand and sterile gauze.
• Decannulation after 72 Hours to 1 Week (Mature Stoma): The stoma tract is established and epithelialized.
  • Emergency Action: Call for help. Hyperextend the client's neck. Insert the obturator into a spare tracheostomy tube (same size or one size smaller, kept at bedside). Lubricate with water-soluble gel, advance smoothly into the stoma at a 45° angle, IMMEDIATELY REMOVE THE OBTURATOR (an obturator completely occludes the airway lumen!), insert the inner cannula, verify bilateral lung sounds, inflate the cuff, and secure ties.