Why would a patient need a respiratory device 24 hours a day?

Why a Patient Needs a Respiratory Device 24 Hours a Day

A patient requires continuous 24-hour respiratory support when they progress to constant hypoventilation with persistent hypercapnia (PCO₂ >50 mmHg) or hypoxemia (SpO₂ <92%) even during waking hours, indicating complete loss of adequate spontaneous ventilation. 1

Clinical Conditions Requiring 24-Hour Support

Neuromuscular Disease Progression

• Patients with Duchenne muscular dystrophy and similar neuromuscular conditions eventually develop constant hypoventilation requiring round-the-clock ventilatory support, typically when mean FVC drops to approximately 0.6 L (5% predicted) 1
• Daytime ventilation becomes necessary when measured waking PCO₂ exceeds 50 mmHg or when hemoglobin saturation remains ≤92% while awake 1
• These patients cannot maintain adequate gas exchange without mechanical assistance during any part of the day 1

Failure to Wean from Acute Support

• Patients who cannot be weaned from non-invasive ventilation (NIV) after acute hypercapnic respiratory failure require referral for long-term 24-hour home ventilation 1
• If NIV is still needed more than one week after an acute episode, this indicates that longer-term continuous ventilation will be necessary 1

Specific High-Risk Populations Requiring 24-Hour Assessment

• Spinal cord lesions with respiratory muscle involvement 1
• Advanced neuromuscular diseases (ALS, muscular dystrophies) 1
• Severe chest wall deformities (scoliosis, thoracoplasty) 1
• Morbid obesity (BMI >30) with obesity hypoventilation syndrome 1

Physiological Indicators for 24-Hour Support

Gas Exchange Criteria

• Persistent hypercapnia with PCO₂ >50 mmHg during waking hours despite optimal medical therapy 1
• Inability to maintain SpO₂ >92% while awake without ventilatory assistance 1
• Progressive worsening of arterial blood gases over 4-6 hours despite NIV, indicating need for continuous support 1

Clinical Deterioration Markers

• Constant use of accessory respiratory muscles even at rest 1
• Inability to speak in full sentences due to breathlessness 2
• Deteriorating conscious level from CO₂ retention 1
• Respiratory rate persistently >30 breaths/min 2

Modes of 24-Hour Ventilatory Support

Non-Invasive Options

• Mouthpiece intermittent positive pressure ventilation allows daytime support without interfering with eating or speaking, successfully used for >8 years in patients with mean FVC 0.6 L 1
• Combination of nocturnal mask ventilation with daytime mouthpiece ventilation provides seamless 24-hour coverage 1
• Glossopharyngeal breathing can supplement mechanical ventilation for brief periods but cannot replace 24-hour support 1

Invasive Support via Tracheostomy

• Tracheostomy should be considered when contraindications or patient aversion to non-invasive ventilation exist, or when severe bulbar weakness prevents effective non-invasive interfaces 1
• Provides more secure ventilator-patient interface for continuous use 1
• Allows higher ventilator pressures in patients with severe chest wall compliance reduction 1

Long-Term Oxygen Therapy Considerations

Duration Requirements for Hypoxemic Patients

• Long-term oxygen therapy (LTOT) should be prescribed for at least 18 hours per day, though 24 hours may be more beneficial for survival in chronic hypoxemia 3
• LTOT 24 h/day versus 15 h/day showed no mortality difference in one large study, but continuous use may optimize correction of hypoxemia 4
• Benefits depend on adequate correction of hypoxemia throughout the entire 24-hour period 3

Monitoring Requirements

• Arterial blood gases should be measured at rest, during exercise, and overnight to confirm adequate oxygenation throughout 24 hours 3
• Continuous SpO₂ monitoring during sleep essential to detect nocturnal desaturation requiring increased support 3

Critical Pitfalls to Avoid

Inadequate Duration of Support

• Providing only nocturnal ventilation when daytime hypercapnia exists will not prevent progressive respiratory failure and mortality 1
• Intermittent support (e.g., only at night) is insufficient once constant hypoventilation develops 1

Oxygen Without Ventilation

• Administering oxygen alone without ventilatory support in patients with obesity hypoventilation syndrome or neuromuscular disease can worsen hypercapnia and precipitate acute respiratory failure 5, 6
• High inspired oxygen concentrations can worsen ventilation/perfusion mismatching in COPD patients with chronic respiratory failure 6

Delayed Recognition

• Waiting until acute decompensation occurs before initiating 24-hour support increases mortality risk 1
• Regular monitoring with arterial blood gases while awake (not just during sleep) identifies patients progressing to constant hypoventilation 1

Escalation Algorithm

When to transition from nocturnal-only to 24-hour support:

1. Measure waking arterial blood gases in all patients on nocturnal ventilation 1
2. If waking PCO₂ >50 mmHg or SpO₂ <92% → initiate daytime ventilation 1
3. If patient cannot maintain adequate gas exchange for >1 week after acute episode → arrange long-term 24-hour support 1
4. If non-invasive methods fail due to bulbar dysfunction or intolerance → consider tracheostomy for continuous ventilation 1