What physiological changes occur after a tracheostomy and how are they managed?

Physiological Changes After Tracheostomy

Tracheostomy fundamentally alters respiratory physiology by bypassing the upper airway, which reduces anatomical dead space by approximately 50%, decreases work of breathing, and eliminates upper airway resistance, but simultaneously removes natural humidification, filtration, and warming mechanisms of the nose and pharynx. 1

Primary Physiological Alterations

Respiratory Mechanics Changes

• Dead space reduction: Bypassing the upper airway (nasopharynx, oropharynx, larynx) eliminates approximately 150 mL of anatomical dead space, improving ventilatory efficiency and reducing the work of breathing 2

• Decreased airway resistance: Removal of upper airway obstruction and laryngeal resistance significantly reduces inspiratory and expiratory effort, facilitating weaning from mechanical ventilation 2, 3

• Improved pulmonary mechanics: Lower resistance allows for easier secretion clearance and more effective cough mechanism through the shorter airway pathway 1, 4

Loss of Natural Airway Defense Mechanisms

• Humidification loss: The nose normally warms inspired air to 37°C and humidifies it to 100% relative humidity; tracheostomy bypasses this, exposing the lower airways to cold, dry air 1

• Filtration compromise: Natural particulate filtration by nasal hairs and mucosa is eliminated, increasing risk of lower respiratory tract contamination 1

• Impaired mucociliary clearance: Dry air thickens secretions and impairs ciliary function, necessitating frequent suctioning 1, 4

Critical Management Strategies

Humidification Requirements

• Heat and moisture exchangers (HME) with viral filters are the preferred method for humidification in tracheostomy patients, providing adequate moisture while maintaining a closed circuit 1

• Heated humidification systems can be used but create open flow of humidified air with increased aerosolization risk 1

• Inadequate humidification leads to mucus plugging, the most common cause of airway emergencies requiring rapid response activation 1, 4

Secretion Management

• Closed-circuit suctioning systems using inline suction catheters are mandatory to prevent airway obstruction while minimizing infection risk 1, 4

• For mechanically ventilated patients, inline suction catheters maintain circuit integrity 1

• For non-ventilated patients, use T-connector or Kelley Circuit with inline suction catheter 1

• Avoid saline instillation before suctioning as it increases coughing and aerosolization without proven benefit 1

• Frequent suctioning prevents mucus buildup, particularly critical in pediatric patients with narrow-lumen tubes 1

Cuff Management Considerations

• Maintaining cuff inflation prevents aspiration and ensures effective positive pressure ventilation but must be balanced against risk of tracheal mucosal injury 1

• Cuff pressure should be monitored with manometer to prevent excessive pressure leading to tracheomalacia or tracheal stenosis 1

• Periodic cuff deflation minimizes pathological healing concerns, but timing must consider aspiration risk 1

Complications Related to Physiological Changes

Immediate Complications (Related to Altered Physiology)

• Subcutaneous emphysema: Air tracking into tissues when tube is partially displaced, managed by immediate tube removal and reassessment 5

• Hemorrhage: Early complication requiring immediate intervention 1, 6

• Tube obstruction from mucus plugging: Most common emergency, prevented by adequate humidification and frequent suctioning 1, 4, 6

Long-Term Complications

• Tracheomalacia: Softening of tracheal cartilage from chronic pressure, related to cuff over-inflation 1

• Tracheal stenosis: Scarring and narrowing of trachea, risk factors include prolonged intubation, large tube size, diabetes, and excessive cuff pressure 1, 6

• Tracheoesophageal fistula: Communication between trachea and esophagus from pressure necrosis 1, 4, 6

• Stomal complications: Infection, granulation tissue, and persistent tracheo-cutaneous fistula 1

Essential Monitoring and Care Protocols

Continuous Assessment Parameters

• Respiratory rate, oxygen saturation, work of breathing, and secretion characteristics must be monitored continuously 1

• Waveform capnography confirms airway patency and adequate ventilation 5, 7

• Warning signs requiring immediate intervention: stridor, obstructed breathing pattern, agitation, increased secretions, or subcutaneous emphysema 1, 5

Equipment Requirements at Bedside

• Functional suctioning system with closed-circuit capability 4
• Oxygen source with delivery devices for both face and stoma 5, 7
• Manual resuscitation bag 4
• Complete tracheostomy kit with tubes one size smaller and larger 4, 8
• Cuff manometer for pressure monitoring 1

Staffing and Communication

• One-to-one nursing until patient is physiologically stable with returned airway reflexes 1

• Written emergency airway management plan must be immediately available and visible 1

• Multidisciplinary team briefing for high-risk patients 1

Common Pitfalls to Avoid

• Never use stiff introducers or bougies to assess patency as they create false passages if tube is displaced 5, 7

• Never delay tube removal in a deteriorating patient; remove immediately and reassess both upper airway and stoma 5, 7

• Never rely solely on pulse oximetry for ventilation monitoring; it detects hypoxemia late and does not assess ventilation 1

• Never perform routine tracheostomy changes before 5-10 days to ensure stoma maturation, as immature tracts recoil making replacement dangerous 1, 7

• Avoid vigorous ventilation through potentially displaced tubes; only use gentle hand ventilation after confirming patency with suction catheter 5