Victoria McCredie minimizing secondary injury #ISICEM19 #IFAD2019
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Secondary brain injury is a frequent event in TBI patients. These events greatly influence prognosis and are potentially preventable. Our understanding of secondary brain injury mechanisms and physiologic responses to treatment is evolving.
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Victoria McCredie minimizing secondary injury #ISICEM19 #IFAD2019
- 1. Minimizing secondary injury Victoria McCredie MBChB PhD Assistant Professor University of Toronto
- 2. Conflicts of interest • Nothing to declare
- 3. Outline The importance of neuroprotection Secondary brain injury targets Neuroprotection at the bedside
- 4. Outline The importance of neuroprotection Secondary brain injury targets Neuroprotection at the bedside
- 6. Maas AI et al. The Lancet Neurology 2008 Macrovascular Microvascular Molecular Importance of differential pathophysiological mechanisms STRUCTURE Microvascular Molecular Inflammation Receptor-mediated damage Oxidative damage Calcium-mediated damage
- 7. Dynamic and PROGRESSIVE process following injury Adapted from Stocchetti N et al. Crit Care 2013 Excitotoxicity Edema Mitochondrial dysfunction Impaired oxygen diffusion Impaired autoregulation, reduced CBF Energy dysfunction Hours Days Inflammation Cortical depolarizations Neurodegeneration TIME Importance of differential pathophysiological mechanisms
- 8. Neuroprotective agents • The focus for neuroprotective strategies has mostly been on pharmacological agents • Preliminary results of these agents were often encouraging • Unfortunately, clinical trials using these candidate neuroprotective agents have consistently produced disappointing results • To date, there is no targeted pharmacological treatment that effectively limits the progression of secondary injury SYNAPSE EPO-TBI PEG-SOD Tirilazad Selfotel Traxoprodil Dexanabinol Magnesium Sulfate COBRIT Perhaps deflected attention from the development of neuroprotective strategies and trials addressing everyday ICU management
- 9. Outcomes improving over time • Despite repeated failures in pharmacological neuroprotection, outcomes for TBI patients have improved • Secular trend in general critical care organization and delivery of care improvements over the past 2 decades • Likely that the organization of intensive treatment has contributed, offering a different kind of neuroprotection based on careful prevention and limitation of intracranial and systemic threats Kramer & Zygun. Can J Anesth 2013 Oct;60(10):966-75 Rosenfeld et al. Lancet. 2012 Sep 22;380(9847)
- 10. Outline The importance of neuroprotection Secondary brain injury targets Neuroprotection at the bedside
- 11. Neurophysiologic targets • Hypoxemia/hyperoxemia • Hypotension • Intracranial hypertension • Hypoglycemia • Fever
- 14. Time is brain Secondary insult ‘dose’
- 15. Pressure*time burden of intracranial hypertension Güiza F et al Intensive Care Med. 2015 Jun;41(6):1067-76 ICP ‘dose’Increasing time spent at ICP level ICP value Worse outcome
- 18. Systolic blood pressure thresholds Systolic blood pressure to decrease mortality: • Patients 15 to 49 yrs: SBP >=110 mmHg • Patients 50 to 69 yrs: at >=100 mmHg • Patients >70 yrs: SBP >=110 mmHg https://www.braintrauma.org/guidelines/guidelines-for-the-management-of-severe-tbi-4th-ed#/:guideline/17-cerebral-perfusion-pressure-thresholds 85 95 105 115 125 135 0 20 40 60 80 100 SBP Age
- 19. • Recommended target CPP for survival and favorable outcomes between 60-70 mmHg • Unclear whether 60 or 70 mm Hg is the minimum optimal CPP threshold • May depend upon the patient’s autoregulatory status https://www.braintrauma.org/guidelines/guidelines-for-the-management-of-severe-tbi-4th-ed#/:guideline/17-cerebral-perfusion-pressure-thresholds Cerebral perfusion pressure thresholds
- 20. Assessment of cerebral autoregulation state All comers ICP 20mmHg 30 mins Ability to tolerate burden of intracranial hypertension Güiza F et al Intensive Care Med. 2015 Jun;41(6):1067-76
- 21. CA intact ICP 20mmHg 150 mins Assessment of cerebral autoregulation state Güiza F et al Intensive Care Med. 2015 Jun;41(6):1067-76
- 22. CA disrupted ICP 20mmHg 15 mins Assessment of cerebral autoregulation state INABILITY to tolerate burden of intracranial hypertension Güiza F et al Intensive Care Med. 2015 Jun;41(6):1067-76
- 24. Are these two patients different? ICP 23 ICP 21 PATIENT A PATIENT B Meyfroidt & Citerio. Neurosurgery 2017 Jul 1;81(1):E1
- 25. Which patient are you more concerned about now? ICP 23 ICP 21 ICP 9 PATIENT A PATIENT B Meyfroidt & Citerio. Neurosurgery 2017 Jul 1;81(1):E1
- 26. Outline The importance of neuroprotection Secondary brain injury targets Neuroprotection at the bedside
- 27. Neuroprotection at the bedside Detection of secondary insults at the bedside 1 Translation of neuroprotective strategies at the bedside 2 Integrated neurophysiologic monitoring Standardized management protocol
- 28. Neuroprotection at the bedside Detection of secondary insults at the bedside 1 Translation of neuroprotective strategies at the bedside 2 Integrated neurophysiologic monitoring Standardized management protocol
- 29. Why is neurological monitoring so important? 1. First 48 hours, up to 40% of TBI patients show a clinically relevant neurological worsening 2. NO neurological deterioration vs neurological deterioration: • Mortality rate of 9.6% vs 56.4% • Favorable outcome of 67.8% vs 29.1% Brown et al. J Trauma 2007 Jun;62(6):1339-44 Iaccarino et al. J Neurosurg 2014 Apr;120(4):908-18 Juul et al. J Neurosurg 2000 Jan;92(1):1-6 Maas et al. Lancet Neurol 2006 Jan;5(1):38-45 Morris et al. Neurosurgery 1998 Dec;43(6):1369-72 Reasons for neurological deterioration: 1. Increased intracranial volume 63.4% 2. Systemic complications 12.5% 3. No definable cause 12.5% 4. Seizures 6.7% 5. Cerebral ischemia 4.8%
- 30. Day 2 ICU TBI • 42 year old male • Severe TBI • GCS E1 M4 VT • Brainstem reflexes intact • Sedated for ICP/brain protective ventilation
- 31. How do we detect secondary brain insults in this comatose patient?
- 32. Standard monitoring ICP/CPP Impaired brain metabolism Brain tissue hypoxia Reduced cerebral blood flow What we know What we need to know Pressure Flow Oxygenation Metabolism
- 33. Randomized ICP <20 mmHg ICP <20 mmHg AND PbtO2 >20 mmHg Okonkwo et al. CCM 2017
- 34. Reduction in brain tissue hypoxia burden ICP only PbtO2 and ICP Tiered PbtO2 management • Decreased total duration of hypoxia by 66% • Decreased average depth of hypoxia by 72% • Reduced area under the curve by 77%Total hypoxia burden (hrs * mmHg)
- 35. It remains to be demonstrated whether multimodal monitoring-guided therapy is able to improve outcome.
- 36. Neuroprotection at the bedside Detection of secondary insults at the bedside 1 Translation of neuroprotective strategies at the bedside 2 Integrated neurophysiologic monitoring Standardized management protocol
- 37. Neurophysiologic-driven protocols in TBI McCredie et al. Crit Care Med. 2018 Jul;46(7):1139-1149
- 38. How can protocols improve patient care? • Aims to improve outcomes by guiding consistent patient care: 1. Facilitate communication 2. Reduce cognitive load 3. Coordinate the interdisciplinary team 4. Increase the adoption of evidence-based interventions and improve adherence to guidelines Chang et al. Critical Care 2012
- 39. Neurocritical care interventions ICU STRUCTURE: DEDICATED NCC UNITS VS GENERAL ICU PROCESS OF CARE: PRESENCE OF A STANDARDIZED TBI MANAGEMENT PROTOCOL McCredie et al. Crit Care Med. 2018 Jul;46(7):1139-1149 ICP PbrO2
- 40. Results Dedicated neurocritical care units were not associated with lower risk-adjusted in-hospital mortality aOR 0.97 (95% CI 0.80-1.19) Standardized management protocols were associated with improved in-hospital mortality aOR 0.77 (95% CI 0.63-0.93) McCredie et al. Crit Care Med. 2018 Jul;46(7):1139-1149
- 41. In conclusion • Our understanding of secondary brain injury mechanisms and physiologic responses to treatment is continually evolving • Moving forward, we must better understand whether these neurophysiologic parameters are modifiable, and whether modification affects relevant outcomes • Neurophysiologic monitoring at the bedside is a DYNAMIC process, not a single measurement • Integrated neuromonitoring may improve situational awareness and allow an individualized approach to therapy
- 43. Questions