Timmons, Shelly

Neuromonitoring Techniques in the Neuro ICU: Brain Tissue Oxygenation Shelly D. Timmons, MD, PhD, FACS, FAANS Director of Neurotrauma Geisinger Health System July 17, 2011

Learning Objectives The attendee will: Be familiar with indications for use of brain tissue oxygenation in traumatic brain injury patients Understand potential pitfalls and complications of brain tissue oxygenation monitoring Understand commonly employed treatments for low brain tissue oxygenation

Balanced Approach Following Guidelines Tailored Therapy

TBI Treatment Goals Actions Reduction of intracranial pressure Maintenance of cerebral perfusion Avoidance of Tissue Hypoxia Goals Prevention of Secondary Injury Reduced Mortality Improvements in Functional Outcome

ICP MAP CBF P bt O 2 Brain Temp Na Osm Plt PT PTT Hgb Hct ABG Gluc Microdialysis CPP SjvO 2 EEG ECOG Neurological Exam Imaging Operative Findings

Indicator of oxygen extraction by brain Measures O 2 saturation in returning blood Compare with arterial O 2 saturation  Arteriovenous Oxygenation Difference (AVDO 2 ) Used to assess CMRO 2 Variations are common from a variety of causes Not commonly used—typically in clinical research centers Jugular Venous O 2 Saturation

Jugular Venous O 2 Saturation High S jv O 2 correlates with Hyperemia / High CBF BUT also correlates with low oxygen extraction in the brain indicating ischemia p bt O 2 is a more direct evaluation of relative cerebral ischemia From: Anesth Analg. 2000 Mar;90(3):559-66 Schell RM, Cole DJ. Techniques may be complimentary

Xenon CT PET MRI CBF Monitor Future Near Infrared Non-Invasive Cerebral Blood Flow

Cerebral Blood Flow Monitor Absolute, real-time continuous perfusion Measured from 0 - 200 ml/100g/min. Thermal diffusion probe -- a minimally invasive (<1 mm diameter), flexible, interstitial catheter

Current technology allows for focal measurements, not global Not a stand-alone monitor but good adjunct pB t O 2 v alues can be manipulated through a variety of interventions Choosing appropriate interventions based upon underlying pathophysiology requires thorough knowledge and understanding of multiple parameters Brain Tissue Oxygenation (pB t O 2 )

Brain Tissue Oxygenation P bt O 2 Measures interstitial brain tissue oxygenation (P bt O 2 ) in mm Hg and brain temperature (°C) Probe inserted approximately 35mm below the dura into the white matter of the brain P bt O 2 used in conjunction with current ICP/CPP monitoring methods

A closed polarographic probe with reversible electrochemical reactions Brain Tissue Oxygenation P bt O 2

Oxygen Accuracy: P bt O 2 0-20 mmHg accuracy is ± 2 mmHg P bt O 2 21-50 mmHg accuracy is ± 10% P bt O 2 51-150 mmHg accuracy is ± 13% Temperature Accuracy: ± 0.2 °C Brain Tissue Oxygenation P bt O 2

Insertion Technique Small Stab Incision Small Drill Hole Placement of Bolt Zeroing of Catheters Insertion of Catheters ICP Brain Temperature / P bt O 2

Techniques ICP Parenchymal Monitor With Ventricular Drainage Advantages Allow for continuous CSF drainage and continuous ICP measurement Allow for intermittent CSF drainage and continuous ICP measurement Allow for fluid-coupled mechanism of ICP confirmation Without Ventricular Drainage Advantages Lower Complication Rate

Brain Oxygen Monitoring Guidelines 2008 Level I Insufficient Data Level II Insufficient Data Level III Jugular venous saturation (<50%) or brain tissue oxygen tension (<15 mm Hg) are treatment thresholds Jugular venous saturation or brain tissue oxygen monitoring measure cerebral oxygenation

Indications Severe TBI (GCS 3-8) Blunt Vascular Injury

P bt O 2 Normal: 25-35 mmHg Low P bt O 2 occurs frequently in the first 24 hours after injury Bardt TF, Unterberg AW, Hartl R, et al. Acta Neurochir 1998; 71:153–156 Dings J, Ja¨ger A, Meixensberger J, et al. Neurol Res 1998; 20(Suppl 1):S71–S75

“ Since the first (mostly European) reports of continuous monitoring of P bt O 2 in humans, investigators have consistently shown correlations of P bt O 2 values with clinical course and outcomes, and of effects on P bt O 2 by various treatment interventions…” Timmons, SD Crit Care Med . 2010 Sep;38(9 Suppl):S431-44. These effects may be independent of effects on ICP or CPP

P bt O 2 and Mortality Risk of death increases < 15 mmHg for 30 minutes < 10 mmHg for 10 minutes P bt O 2 < 5 mmHg high mortality P bt O 2 < 2mmHg neuronal death Bardt TF, Unterberg AW, Hartl R, et al. Acta Neurochir 1998; 71:153–156 N.B. Good outcomes are possible even with hypoxic episodes

P bt O 2 and Mortality Time with P bt O 2 < 10 mm Hg < 30 minutes vs. > 30 minutes Bardt et al. 1998 6-Month GOS 35 Severe TBI Pts.

Low P bt O 2 and Mortality Association with increased mortality Increasing duration of time < 15 Any value < 6 also Valadka AB, Gopinath SP, Contant CF, et al. Crit Care Med 1998; 26:1576–1581 Dings J, Ja¨ger A, Meixensberger J, et al. Neurol Res 1998; 20 (Suppl 1):S71–S75

Low P bt O 2 and Mortality Increased mortality with shorter time periods as P bt O 2 decreases 50% Mortality <5 30 minutes <10 105 minutes <15 240 minutes 6-Month GOS 101 Severe TBI Patients Van den Brink et al. 2000 Effects of obliterated cisterns

Low P bt O 2 and Mortality Desaturations can occur even with acceptable ICP and CPP levels These associated with higher mortality Targeted therapies can improve outcome, even in the face of normal ICP/CPP Additional benefit in the diffuse injury group Stiefel MF, Spiotta A, Gracia VH, et al. J Neurosurg 2005; 103:805–811 Stiefel MF, Udoetuk JD, Spiotta AM, et al. J Neurosurg 2006; 105:568–575 Narotam PK, Morrison JF, Nathoo N J Neurosurg 2009; 111:672–682

Low P bt O 2 Causes Several correctable causes of cerebral oxygen desaturations Insufficient CPP Vasospasm Pulmonary atelectasis resulting in hypoxemia Anemia Premature interruption of ICP-controlling medications Artru F, Jourdan C, Perret-Liaudet A, et al. Neurol Res 1998; 20:S48–S51

Techniques to Improve P bt O 2 Elevation of CPP Increases in Blood Volume, MAP Decreases in ICP Hypertonic saline Pressors Sedatives Barbiturates Independent of fx on ICP  cerebral metabolism Artru F, Jourdan C, Perret-Liaudet A, et al. Neurol Res 1998; 20:S48–S51 Cormio M, Gopinath SP, Valadka AB, et al. J Neurotrauma 1999; 16:927–936 Johnston AJ, Steiner LA, Coles JP, et al. Crit Care Med 2005; 33:189–195 Oddo M, Levine JM, Frangos S, et al. J Neurol Neurosurg Psych 2009; 80:916–920 Narotam PK, Morrison JF, Nathoo N J Neurosurg 2009; 111:672–682 Kiening KL, Ha¨rtl R, Unterberg AW, et al. Neurol Res 1997;19:233–240 Imberti R, Fuardo M, Bellinzona G, et al. J Neurosurg 2005; 102:455–459 Thorat JD, Wang EC, Lee KK, et al. J Clin Neurosci 2008;15: 143–148 Chen HI, Malhotra NR, Oddo M, et al. Neurosurgery 2008;63:880–997

Techniques to Improve P bt O 2 Transfusion of Packed Red Blood Cells (PRBCs) Increases P bt O 2 Improved oxygen-carrying capacity of the blood Effect more prominent in the presence of higher lactate/pyruvate ratios (mitochondrial dysfunction) Smith MJ, Stiefel MF, Magge S, et al. Crit Care Med 2005; 33:1104–1108 Leal-Noval SR, Rincon-Ferrari MD, Marin-Niebla A, et al. Intensive Care Med 2006; 32: 1733–1740 Zygun DA, Nortje J, Hutchinson PJ, et al. Crit Care Med 2009; 37:1074–1078

Techniques to Improve P bt O 2 Transfusion of Packed Red Blood Cells (PRBCs) Increases in P bt O 2 independent of CPP changes Cardiac index Peripheral oxygen saturation FiO 2 Artru F, Jourdan C, Perret-Liaudet A, et al. Neurol Res 1998; 20:S48–S51 Leal-Noval SR, Rincon-Ferrari MD, Marin-Niebla A, et al. Intensive Care Med 2006; 32: 1733–1740 Smith MJ, Stiefel MF, Magge S, et al. Crit Care Med 2005; 33:1104–1108

Techniques to Improve P bt O 2 Conflicting data exist on baseline P bt O 2 effects on improved P bt O 2 Age of the transfused blood products may affect efficacy (storage > 19 days) Leal-Noval SR, Rincon-Ferrari MD, Marin-Niebla A, et al. Intensive Care Med 2006; 32: 1733–1740 Zygun DA, Nortje J, Hutchinson PJ, et al. Crit Care Med 2009; 37:1074–1078 Weigh well-documented risks vs. the potential benefit of protection from secondary injury

Techniques to Improve P bt O 2 Increasing Ventilatory FiO 2 to supranormal levels (normobaric hyperoxia) can increase P bt O 2 BUT May not lead to better CBF or cerebral metabolic rate of oxygen consumption Tolias CM, Reinert M, Seiler R, et al. J Neurosurg 2004; 101: 435–444 Nortje J, Coles JP, Timofeev I, et al. Crit Care Med 2008; 36:273–280 Diringer MN, Aiyagari V, Zazulia AR, et al. J Neurosurg 2007; 106: 526–529

Techniques to Improve P bt O 2 Primary lung function can affect the cerebral oxygenation response to administration of hyperoxic challenges. P a O 2 /FiO 2 ratios of 200–250 are associated with decreased cerebral oxygenation responsiveness Important to determine the pulmonary status Monitoring of P a O 2 /FiO 2 ratios Early diagnosis of ventilator-acquired pneumonia Rockswold GL, Solid CA, Paredes-Andrade E, et al. Neurosurg 2009; 65:1035–1042 Rosenthal G, Hemphill JC, Sorani M, et al. Crit Care Med 2008 Jun; 36:1917–1924

Techniques to Improve P bt O 2 Decompressive Hemicraniectomy Stiefel MF, Heuer GG, Smith MJ, et al. J Neurosurg 2004; 101:241–247 Ho CL, Wang CM, Lee KK, et al. J Neurosurg 2008; 108:943–949 Used w/ permission: William Coplin, M.D. Contralateral to Surgical Site

Relationship to CBF Correlation shown with Xenon CT, CT perfusion studies, and non-invasive monitoring Limitations in measurement ability Non-correlated variations also occur Changing oxygen demands and delivery CO 2 reactivity Coupling/uncoupling of cerebral metabolism to CBF in patients with brain pathology

Oxygen Diffusion Impaired after brain injury Perivascular edema Endothelial edema Microvascular collapse Resulting in Impaired oxygen extraction Even with hypoperfusion (Extraction should be higher) Low P bt O 2 may be more closely related to impaired oxygen diffusion rather than oxygen delivery or metabolism. Diringer MN, Aiyagari V, Zazulia AR, et al. J Neurosurg 2007; 106: 526–529 Menon D, Coles JP, Gupta AK, et al. Crit Care Med 2004 Jun; 32: 1384–1390 Rockswold SB, Rockswold GL, Zaun DA, et al. J Neurosurg 2010; 112:1080–1094 Mannitol

Potential Problems Pitfalls Catheters are stable Factors affecting readings: Calibration over first two hours Dislodgement of catheter Catheter breakage Complications Complication rates are low Hematoma Infection Van Santbrink H, Maas AIR, Avezaat CJJ Neurosurgery 1996; 38: 21–31 Dings J, Meixensberger J, Roosen K J Neurological Res 1997; 19:1–5 Van den Brink WA, Van Santbrink H, Steyerberg EW, et al. Neurosurgery 2000; 46: 868–878 Anderson, RCE, Kan P, Klimo P, et al. J Neurosurg (Pediatrics 2) 101:53–58, 2004

Assessing Physiology of Secondary Injury “ Global” ICP CPP CBF S jv O 2 “ Regional” P bt O 2 Microdialysis PET ECOG

Future of Neuromonitoring Storage & Interpretation of Ever More Continuous Physiological Data Multimodality Monitoring Linkage to Events Movements/Transport Imaging Surgeries and Other Procedures Family Visits Nursing Care Bathing/Turning/Suctioning Drug Administration O 2 Desaturations Lab Derangements Seizures Linkage to Examination GCS Pupils Ultimately Linkage to Outcomes Will Aid in Research and More Evidence-Driven Approaches to TBI Not Just ICP Control But Also Metabolism-Driven Therapy

TBI Advisor Evidence-Based Treatments  Interventions

Timmons, Shelly

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