Does raised Intracranial Pressure (ICP) cause shivering?

Relationship Between Raised Intracranial Pressure and Shivering

Raised intracranial pressure (ICP) does not directly cause shivering, but shivering can worsen elevated ICP by increasing cerebral metabolic stress and reducing brain tissue oxygenation. 1

Pathophysiological Relationship Between Shivering and ICP

Shivering is primarily a thermoregulatory response, but its relationship with ICP is clinically significant:

• Shivering can reduce brain tissue oxygenation, leading to cerebral metabolic stress, which may worsen outcomes in patients with elevated ICP 1
• When ICP is labile and shivering is detected, it requires prompt management to prevent secondary brain injury 1
• Shivering is particularly problematic during targeted temperature control (TTC), as it can negate the neuroprotective benefits of temperature management 1

Clinical Management of Shivering in Elevated ICP

When shivering occurs in patients with elevated ICP, a stepwise approach to management is recommended:

1. Assessment and documentation of shivering in patients with elevated ICP is essential 1

2. First-line treatments for shivering control:

   • NSAIDs
   • Opiates
   • Magnesium
   • Counter warming techniques 1

3. Second-line treatments when ICP is labile:

   • Ensure appropriate depth of sedation first
   • Consider neuromuscular blockers after adequate sedation 1
   • Titration of sedation with agents like propofol or etomidate 2

4. Monitoring considerations:

   • EEG monitoring may be valuable as it can detect subclinical epileptic activity that could increase ICP 1
   • Continuous monitoring of EEG spectrum, BAEPs, and SSEPs can complement ICP monitoring 1

Special Considerations

Temperature Management

• In patients with traumatic brain injury (TBI), controlled rewarming with automated feedback-controlled devices may reduce the risk of rapid temperature variations that can precipitate secondary brain injury 1
• Rebound hyperthermia should be prevented when discontinuing therapeutic hypothermia, as it can worsen ICP 1

Risk-Benefit Assessment

• In self-ventilating patients in the subacute phase of severe TBI, an individualized risk-benefit assessment should be undertaken regarding strict indications of controlled normothermia 1
• Permissive hyperthermia may be considered in cases where the risk of secondary brain injury from pyrexia is thought to be low, especially if shivering cannot be controlled with first-line treatments 1

Practical Management Algorithm

1. Detect and assess shivering in patients with elevated ICP
2. Implement first-line treatments:
   • NSAIDs, opiates, magnesium, counter warming
3. If shivering persists and ICP is labile:
   • Ensure adequate sedation
   • Consider neuromuscular blockers
4. Monitor for effectiveness of shivering control and ICP response
5. Consider temperature management strategy based on patient's condition and risk of secondary brain injury

Pitfalls and Caveats

• Neuromuscular blocking agents should only be used after ensuring appropriate depth of sedation 1
• When using pharmacologic agents for shivering management, monitor for efficacy (shivering control) and safety (adverse events and drug-drug interactions) 1
• Differentiating EEG alterations due to metabolic disturbances from those due to increased ICP can be challenging 1
• Concurrent use of sedative drugs and hypothermia can influence brain electrical activity, complicating interpretation 1

By understanding the relationship between shivering and ICP, clinicians can implement appropriate management strategies to prevent secondary brain injury and optimize patient outcomes.