In a quadriplegic patient with C6 spinal cord injury on tracheostomy receiving continuous positive airway pressure (assist pressure 12 cm H₂O, positive end‑expiratory pressure 5 cm H₂O, FiO₂ 40%) who reports dyspnea, has hypotension despite intravenous fluids, and develops bradycardia when bilevel positive airway pressure (BiPAP) is attempted, what are the likely underlying causes and what should be the next management steps?

Management of Ventilatory Failure and Bradycardia in C6 Quadriplegic Patient

The bradycardia episodes during BiPAP attempts are most likely caused by unopposed parasympathetic stimulation from autonomic dysreflexia triggered by airway manipulation, and should be treated with aminophylline or theophylline rather than atropine, while the persistent dyspnea and ventilator dependence reflect inadequate secretion clearance requiring mechanically-assisted cough devices and aggressive bronchial drainage physiotherapy. 1

Underlying Causes of Current Clinical Picture

Bradycardia with BiPAP Attempts

• Severe sinus bradycardia is common in the acute recovery phase after spinal cord injury due to acute reduction in sympathetic tone, with both incidence and severity directly related to the level and severity of injury 1
• Cardiac arrest from sinus arrest and asystole occurs in 16% of patients with severe cervical spinal injury during the first 2-4 weeks after injury 1
• Common triggers for bradycardia episodes include tracheal suctioning and turning the patient, which explains why BiPAP initiation (involving airway manipulation) precipitates bradycardia 1
• The bradycardia is attributable to unopposed parasympathetic stimulation rather than primary cardiac pathology 1

Persistent Dyspnea and Ventilator Dependence

• C6 injuries cause significant expiratory muscle weakness while preserving some diaphragmatic function, leading to ineffective clearance of secretions 2
• Patients with C6 injuries have compromised ability to generate adequate expiratory pressures needed for effective cough, resulting in secretion retention 2
• Reduced lung volumes and inability to take deep breaths impair the normal mucociliary escalator function 2
• The current CPAP settings (assist pressure 12, PEEP 5, FiO₂ 40%) may be inadequate for this patient's needs given persistent symptoms 1

Hypotension Despite Fluid Resuscitation

• Patients with high cervical spinal cord injury (C1-C5) have significantly greater requirement for cardiovascular intervention compared with lower injuries (C6-C7), though C6 injuries still carry substantial risk 3
• Neurogenic shock was present in 24-31% of cervical spinal cord injury patients regardless of exact level 3
• The hypotension likely reflects persistent autonomic dysfunction rather than hypovolemia if fluids have been adequate 3

Immediate Management Steps

Treatment of Bradycardia

Aminophylline or theophylline is reasonable to increase heart rate and improve symptoms in patients with bradycardia associated with acute spinal cord injury 1

• Atropine and inotropes are often used but are not always effective because the primary abnormality is unopposed parasympathetic stimulation 1
• Adenosine receptor blockade by theophylline or aminophylline targets the underlying pathology and has been shown effective in case series 1
• Methylxanthines can usually be withdrawn after 4-6 weeks, and side effects or adverse events are rare 1
• Temporary pacing is another potential approach for treating hemodynamically significant sinus bradycardia associated with spinal cord injury 1

Respiratory Management Bundle

A bundle approach is recommended to facilitate respiratory weaning in patients with traumatic cervical cord injury, combining: 1, 2

1. Active physiotherapy and mechanically-assisted insufflation/exsufflation device (Cough-Assist) to remove bronchial secretions 1, 2
2. Aerosol therapy combining beta-2 mimetics and anticholinergics 1, 2
3. Abdominal contention belt during periods of spontaneous breathing or raising procedures 1

Ventilator Mode Considerations

CPAP is indicated in hypoxemic respiratory failure, while BiPAP is possibly considered in certain patient groups with type 2 respiratory failure 1

• Given the bradycardia with BiPAP attempts, continue CPAP but optimize settings: consider increasing CPAP to 10-15 cmH₂O if tolerated, with FiO₂ adjusted to maintain SpO₂ 92-96% 1
• BiPAP may be associated with decreased cardiac output and cardiac index at pressures of 10/5 cmH₂O or higher due to reduced venous return 4
• Intrathoracic pressure increases to approximately 50% of the pressure delivered at the mask, which may explain the bradycardia response in this autonomically unstable patient 4

Critical Pitfalls to Avoid

Do Not Use Atropine as Primary Therapy

• Sinus bradycardia requiring medical therapy is persistent and refractory to atropine and other adrenergic drugs in spinal cord injury patients 1
• Atropine is ineffective because the mechanism is unopposed parasympathetic stimulation requiring adenosine receptor blockade 1

Do Not Delay Tracheostomy Decision

• The main risk factors for mechanical ventilation weaning failure are upper level spinal cord injury (above C5) and complete spinal cord injury 1
• While C6 is technically below C5, this patient has been struggling for 2 months, suggesting consideration for tracheostomy
• Experts suggest performing tracheostomy only after one or more tracheal extubation failures in patients with lower cervical spinal cord injury (C6-C7) 1
• However, given the prolonged course, early tracheostomy may accelerate ventilatory weaning 1

Monitor for Aspiration Risk

• Cervical spine injuries can compromise neural pathways that innervate the larynx, leading to sensory deficits in the laryngeal mucosa 5
• Diminished laryngeal mucosal sensation increases the risk of silent aspiration as the protective cough reflex may be impaired 5
• The combination of sensory deficits and motor impairment can significantly increase morbidity and mortality due to respiratory complications 5

Specific Next Steps Algorithm

1. Initiate aminophylline or theophylline for bradycardia management before attempting further BiPAP trials 1

2. Implement mechanically-assisted insufflation/exsufflation device immediately for secretion clearance 1, 2

3. Add aerosol therapy with beta-2 mimetics and anticholinergics 1, 2

4. Optimize CPAP settings (increase to 10-12 cmH₂O if tolerated) rather than forcing BiPAP transition 1

5. Apply abdominal contention belt during spontaneous breathing attempts 1

6. Reassess after 1-2 weeks of optimized bundle therapy; if no improvement, proceed with tracheostomy 1

7. Monitor potassium levels if using methylxanthines 1