Respiratory Complication Risks and SCI

The key message about respiratory function after SCI is that respiratory complications are one of the most common causes of mortality. Hence, preventative management of all respiratory complication risks, along with deliberate monitoring for signs and symptoms, results in better health outcomes for a person with SCI.

ACUTE: Risk Assessment and Management

Pulmonary Embolism (PE)

Similar to venous thromboembolism (VTE), PE is a significant risk due to the resultant venous stasis and hypercoagulability following SCI. The impact of paralysed muscles, immobility and potentially cardiovascular changes from autonomic dysfunction, can compound the risk.

Overall, the risk of PE increases with:

• acute, high-level motor complete SCI, especially the first 2 weeks after injury: although the risk remains higher than in age-matched populations for 3-6 months following injury
• multi-trauma, especially lower limb or pelvic fractures
• increasing age
• history of previous VTE
• delayed or absent thromboprophylaxis, although people receiving appropriate chemical thromboprophylaxis can also experience a VTE  
• dehydration

Adequate thromboprophylaxis (pharmacological and mechanical) is considered best practise in preventing or reducing the incidence of PE.

Investigation and management of suspected PE is considered a clinically urgent issue and should be escalated to treating medical staff promptly. 

Signs and symptoms of PE may include: 

• arrythmia including tachycardia 
• shortness of breath especially with decreased oxygen saturations 
• chest pain (usually worse with breathing) 
• unexplained low-grade temperature or fevers 
• a feeling of anxiety, dizziness or syncope 
• acute confusion with no chest pain 

Management: See Venous Thromboembolus Prophylaxis link

Pulmonary Oedema

The risk of pulmonary oedema developing following an acute SCI is multifactorial. Again potential cardiovascular changes from autonomic dysfunction combined with excessive fluid resuscitation in the presence of hypotension are some of the main contributing factors.

Aspiration

Aspiration risk increases when airway protection is compromised. This could be related to changes in consciousness, neck movement, ability to effectively cough and/or swallow.

Overall the risk of aspiration increases with:

• acute, high-level motor complete SCI
• immersion injury, traumatic brain injury, concussion or loss of consciousness
• an episode of vomiting eg. while wearing fixed neck positioning device (collar, halo brace)        *This is a medical emergency: providing support to maintain spinal alignment, the person with SCI should be rolled and provided airway clearance and ventilation support as required
• anterior cervical discectomy and fusion: surgical hardware, soft tissue swelling, recurrent laryngeal nerve injury
• insertion of tracheostomy tubes
• extubation
• insertion of nasogastric tubes, radiologically inserted gastronomy (RIG), percutaneous endoscopic gastronomy combined with
  • overfeeding
  • paralytic ileus/reduced bowel motility
• presence of dysphagia +/- risk feeding behaviours

Signs and symptoms for suspected aspiration may include:

• awkward or incomplete swallow: watery eyes, audible swallow, wet vocalisation, drooling, cough or choking
• assessed changes in laryngeal function
• reduced and altered breath sounds on auscultation
• low O2 pulse oximetry
• shortness of breath and change in respiratory rate
• increased heart rate
• elevated temperature
• radiological imaging demonstrating lung collapse
• recurrent respiratory tract infections: ‘silent aspiration’ including saliva

Management: Immediate airway clearance, antibiotic therapy + See Voice, Speech and Swallow Management link +Ventilation, Noninvasive Ventilation links+ Lung Volume Inflation/Recruitment, Secretion Management links

Atelectasis  

Atelectasis commonly develops after a SCI due to weakness and paralysis of the respiratory muscles resulting in hypoventilation, reduced lung and chest wall compliance and secretion retention. This is accelerated by any autonomic dysfunction which results in decreased surfactant production yet increased secretion production, airway bronchospasm and pulmonary oedema. If not addressed, increasing atelectasis contributes to other risks such as pneumonia or respiratory failure.

Overall, the risk of atelectasis increases with:

• acute, high-level motor complete SCI, especially the first weeks after injury
• multi trauma including lung injury eg. immersion, pneumothorax, aspiration
• post-surgical management for other injuries, including spinal stabilisation
• pre-existing lung disease eg COPD
• inadequate secretion management, but also ventilation and lung volume inflation management
• prolonged mechanical invasive ventilation
• prolonged periods of immobilisation in bed

Signs and symptoms of atelectasis may include: 

• presence of paradoxical breathing as this indicates inefficiency and increased work of breathing
• reduced and altered breath sounds on auscultation
• low O2 pulse oximetry
• shortness of breath and change in respiratory rate
• increased heart rate
• elevated temperature
• radiological imaging demonstrating lung collapse

Management: See Ventilation, Noninvasive Ventilation, Lung Volume Inflation/Recruitment, Secretion Management links

Pneumonia

The risk of pneumonia increases with acute, high-level SCI and is an inflammation process, usually caused by a bacterial infection, secondary to a virus:

• results from atelectasis and retained secretions
• is compounded by inadequate secretion management, but also lung ventilation and inflation, permitting bacteria growth

Overall, the risk of pneumonia increases with:

• acute, high-level motor complete SCI, especially the first weeks after injury
• associated lung injury eg. immersion, pneumothorax, aspiration
• pre-existing lung disease eg COPD
• cross contamination eg.
• inadequate secretion management, but also ventilation and lung volume inflation management
• prolonged mechanical invasive ventilation
• prolonged periods of immobilisation in bed

Management: Antibiotic therapy + See Voice, Speech and Swallow Management link +Ventilation, Noninvasive Ventilation, Lung Volume Inflation/Recruitment, Secretion Management links

Respiratory Failure

Respiratory failure is one of the most common and serious respiratory complications following acute SCI. Alveolar hypoventilation and a ventilation perfusion mismatch (shunted) ensues when the respiratory load exceeds the ability of the brain’s respiratory central drive and the remaining respiratory muscles to maintain adequate gas exchange. Acute respiratory failure is often associated with respiratory muscle fatigue.

For a video explanation of respiratory failure see here:

Respiratory Failure – type 1 vs type 2 | in 2mins! (youtube.com)

This risk should be determined by comprehensive respiratory function assessment, to adequately anticipate the required preventative management.

Overall, the risk for developing acute respiratory failure increases with:

• acute, high-level motor complete SCI
• presence of paradoxical breathing and increased work of breathing
• increasing hypoxaemia and hypercapnia
• associated lung injury eg. immersion, pneumothorax
• pre-existing lung disease eg COPD
• development of other complications: atelectasis, aspiration, pneumonia
• inadequate early ventilation support
• attempting upright mobilisation too early +/- with inadequate ventilatory support

Management: Ventilation, Noninvasive Ventilation, Lung Volume Inflation/Recruitment, Secretion Management links

Ascending Myelopathies

In the acute phase following a SCI, it is possible for neurological deterioration to ascend a few levels as inflammatory markers cause progressive oedema and compromise vascular supply to adjacent levels in the spinal cord. Less commonly, subacute posttraumatic ascending myelopathy (SPAM) can occur some weeks after SCI, although the pathophysiology is less clear. More chronically, syringomyelia may develop due to abnormal cerebrospinal fluid circulation and the formation of fluid-filled cavities (syrinx) within the spinal cord. Any neurological deterioration following high-level SCI can have a significant effect on respiratory function, so the importance of adequate assessment and monitoring as well as early intervention is highlighted.

Management: Ventilation, Noninvasive Ventilation, Lung Volume Inflation/Recruitment, Secretion Management links

CHRONIC: Risk Assessment and Management

Although the above risks may be reduced in a person with a chronic SCI, their risk profile increases when becoming acutely unwell and requiring hospitalization, even for non-respiratory health issues.

Standard risk management practises should be reintroduced, but consideration also given for any longer-term management in the community if needed. A multidisciplinary team review may be required to assess contributing factors and introduce management strategies.

For more information see Long Term SCI Changes: Impact on Respiratory Function