Edwin G. Avery, IV, MD, CPI Chief, Division of Cardiac Anesthesia University Hospitals Case Medical Center Associate Professor of Anesthesiology Case Western Reserve Univ. School of Medicine
Covidien: consultant, speaker’s bureau, funded research
Alere: funded research
Medtronic: funded research
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How does it work: general concepts Near-InfraRed Spectroscopy (NIRS) and regional cerebral oxygenation (rSO2) Validation work Why it is helpful‌ Baseline values (normal v. abnormal) Clinical studies Clinical use of rSO2 A-Star Research
How it works‌
Real-time, non-invasive detection of regional tissue oxygen saturation using transillumination spectroscopy NIR light wavelengths (690-880 nm) nm have the unique ability to penetrate several centimeters into the tissue and thus can be used to measure regional tissue oxygen saturation (rSO2) First commercial cerebral oximetry device approval by FDA was May 1993 (INVOS 3100)
Regional O2 saturation (rSO2): 1.Provides a unique venous weighted measure of O2 balance at the gas exchange site 2.Reflects real-time changes in regional tissue perfusion adequacy 3.May precede changes in systemic parameters
Microcirculation ( vessels < 100 µm) contains half of the body’s blood volume.
rSO2
Tobias JD. Cerebral Oximetry Monitoring with Near Infrared Spectroscopy Detects Alterations in Oxygenation Before Pulse Oximetry. J Intensive Care Med. 2008; 23:384388 †
Assumed percentage of venous blood is device specific & fixed (i.e. INVOS 75%)
Despite the relatively small volume of tissue being interrogated by NIRS cerebral oximetry (i.e. ~15 mm3) it may serve as an index organ reflecting the adequacy of tissue oxygenation throughout the entire body.
< 100 microns (0.1 mm) in diameter
2010 Avery EG, White paper
What exactly is being measured? Venous weighted (75%) oxy-Hb percent saturation in the microcirculationâ&#x20AC; Oxy-Hb in the venous circulation is back calculated from measuring both total Hb and deoxy-Hb â&#x20AC; Blood flow need not be pulsatile (or even flowing at all) to obtain an accurate measurement 2010 Avery EG, White paper www.casecag.com
A blurry, not absolute, window allowing insight into tissue O2 balance
â&#x20AC;&#x153;Banana/curvilinear arcâ&#x20AC;?
Arc sensor (distal detector) Arc sensor (proximal detector)
Adhesive pad Light emitting diode (LED)
Hongo K, Kobayashi S, Okudera H, Hokama M, Nakagawa F. Noninvasive Cerebral Optical Spectroscopy: Depth-resolved Measurements of Cerebral Haemodynamics Using Indocyanine Green. Neurol Res 1995;17: 89-93
Receptors Sensor PAD
lp Sca iu m n a r C a Dur
LED
h no c a r /A
Fron Hb
id
Predictable path Banana arc Spatially resolved
y a r g tal
ter t a m
Lambert-Beer Law + Scatter Correction
There are currently five FDA cleared devices‡ that are marketed to assess cerebral oxygenation which include: Somanetics INVOS
CASMED – Fore-sight
2λ
Laser light
4λ
(~20 years of clinical use)
Nonin – Equanox Ornim – Cerox
3,4λ Ultrasound tagged NIR light
4λ
(2 models)
‡Devices listed in order of FDA clearance 2010 Avery EG, White paper. Gagnon RE, Macnab AJ, Gagnon FA, et al. Comparison of Two Spatially Resolved NIRS Oxygenation Indices. J Clin Monit 2002;17:385-91
The validation of rSO2 monitoring is challenged by the fact that there is no gold standard, standard or index test, invasive or non-invasive of cerebral oxygenation.
2010 Avery EG, White paper www.casecag.com
†
• Balloon test occlusion w/ SPECT + cerebral oximeter + ↓stump pressure (r=0.85; p<0.0001) • Desaturation >8% = low flow + ischemic symptoms Kaminogo M, Ochi M, Onizuka M, Takahata H, Shibata S. An Additional Monitoring of Regaionl Cerebral Oxygen Saturation to HMPAO SPECT Study During Balloon Test Occlusion. Stroke. 1999; 30:407-413 †rSO2 data on file at Covidien, Boulder, CO.
SaO2 - Systemic arterial oxygen availability SpO2 - Depends on pulsatile blood flow and measures only the oxy-Hb in arterial blood as it leaves the heart TiPO2 - Partial pressure of O2 in cerebral tissue SvO2 - Mixed venous saturation SjvO2 â&#x20AC;&#x201C; Jugular venous saturation rSO2 â&#x20AC;&#x201C; A venous weighted value (75% venous:25% arterial) that measures the regional relative concentrations of oxy-Hb and deoxy-Hb; it represents the venous reserve capacity following tissue oxygen extraction 2010 Avery EG, White paper; Marin and Moore. Understanding Near-Infrared Spectroscopy. Advances in Neonatal Care. Vol 11, No 6, pp 382-388
Relevant Comparative Variables: rSO2 vs. SaO2, TiPO2, SvO2, SjvO2 , f SO2 Reference
Title
Methods
Results
Conclusions
J Clin Monit 2000;16:191-9
Estimation of Jugular Venous O2 Saturation from Cerebral Oximetry or Arterial O2 Saturation During Isocapnic Hypoxia
Prospective, observational N=42 healthy adults Varied FiO2 with isoand hypercapnia INVOS
rSO2 & SjvO2, r=0.9 SaO2 & SjvO2, r=0.77
Compared with SjvO2, the rSO2 values correlated more closely than SaO2 ; SjvO2 changed > rSO2 with hypercapnia
Neurol Res 1997; 19:246-8
Dynamic Changes of Cerebral Oxygenation Measured by Brain Tissue Oxygen Pressure and Near Infra-red Spectroscopy
Prospective, observational N=10 Neuro ICU tiPO2 and rSO2 NIRO 300
rSO2 & tiPO2, r=0.73
Compared with tiPO2, the rSO2 values correlated well in head injured subjects
Interactive Cardiovasc Thorac Surg 2011; 0 (Dec):1-5
Non-invasive Cerebral Oxygenation Reflects Mixed Venous Oxygen Saturation During the Varying Haemodynamic Conditions in Patients Undergoing Transapical Transcatheter Aortic Valve Implantation
Prospective, observational N=20 TA-TAVI SvO2 and rSO2 at 6 time points FORESIGHT
rSO2 & SvO2, r=0.76
Compared with SvO2, the rSO2 values correlated well in TA-TAVI subjects indicating that rSO2 reflects systemic O2 balance
Validation
OF Pre-CPB Mx CPB-cooling Mx CPB-warming Mx Post-CPB Mx
FL AB EL
= 0.17 = 0.28 (34%>0.4) = 0.40 (53%>0.4) = 0.27
Stroke 2010;41:1951-6 Anes & Analg 2012;116:834-40
Several validation studies of NIRS rSO2 have been published using an array of comparative physiologic variables and all similarly conclude that although there is no index test to compare rSO2 values with, the observed data appears to reflect dynamics of regional cerebral oxygen balance. Of note, caution should be taken in extrapolating the results of validation studies â&#x20AC; performed with the INVOS monitor to the other devices which claim to measure the same parameter because the internal processing algorithms and physical characteristics of the five FDA approved devices are all unique and key to the clinical data that they generate. â&#x20AC;
Few validation studies are published in the peer reviewed literature
Protecting the tissue oxygen balance in the brain, a highly metabolically active tissue, will likely protect the other bodily organs and thus provide general, but measurable clinical outcome improvements in patients monitored with this technology when an appropriate interventional algorithm is used
The noninvasive INVOS 5100C is intended for use as an adjunct monitor of regional hemoglobin oxygen saturation of blood in the brain or in other tissue beneath the sensor. It is intended for use in individuals greater than 2.5 kg at risk for reduced-flow or non-flow ischemic states. Its FDA clearance was based upon data generated from healthy subjects.
Normative rSO2 values are device specific. INVOS values: Healthy adults Healthy children Healthy neonates Adult w/CV disease Pedi w/CV disease
= 71 ± 6% = 71 ± 7% = 76 ± 8% = 67 ± 9% = 60 ± 12%
Abnormal values are not well defined but analysis of the literature suggests that values that deviate from normative values in patients undergoing CV surgery are associated with poor clinical outcomes. Abnormal values likely represent poor functional organ reserve in the cardiovascular and pulmonary systems.
Study Design: •Multicenter, prospective, blinded, randomized and controlled trial of 122 elderly, high risk general surgery (major abdominal†) patients – Subjects were expected >2 hour operation and were >65 YOA
Hypothesis: •rSO2 monitoring with active intervention during cerebral desaturations in elderly patients undergoing major abdominal surgery will reduce the potential exposure of the brain to inadequate oxygen supply
Anesth Analg. 2005;101(3):740-747
†
Conclusion: •Cerebral desaturations were common (~20% of patients) during major abdominal surgery in the elderly and reacting to these events prevented exposure of the brain to potential hypoxia. Effective treatment of these cerebral desaturations resulted in decreased PACU and Hospital LOS and less cognitive decline (as assessed by MMSE scores)
Control (electronic blinding)
Xiphopubic skin incision for gastric/colonic or hepatic resection, duodenocephalo-pancreasectomy
Intervention
Goal for intervention group was to maintain INVOS rSO2 values above 75% of subjectâ&#x20AC;&#x2122;s established room air baseline. The number of subjects experiencing cerebral desaturation was similar between the control and intervention groups.
Control Group n = 15 (23%) subjects With rSO2 Desaturation
Study Group n = 11 (20%) subjects With rSO2 Desaturation
p = 0.82 Casati A, Fanelli G, Piertropaoli P, et al. Continuous Monitoring of Cerebral Oxygen Saturation in Elderly Patients Undergoing Major Abdominal Surgery Minimizes Brain Exposure to Potential Hypoxia. Anesth Analg.. 2005; Sep;101(3):740-7
P = 0.017 P = 0.002
P = 0.01
P = 0.02 P = 0.007
Casati A, Fanelli G, Piertropaoli P, et al. Continuous Monitoring of Cerebral Oxygen Saturation in Elderly Patients Undergoing Major Abdominal Surgery Minimizes Brain Exposure to Potential Hypoxia. Anesth Analg.. 2005; Sep;101(3):740-7
Studydiscussions.com
Study Design: Prospective, randomized, blinded, controlled CAB Study, 200 patients Hypothesis: By using the brain as an index organ, interventions to optimize cerebral perfusion will have a similarly beneficial effect on systemic tissue perfusion and clinical outcomes
Conclusion: â&#x20AC;&#x153;Monitoring cerebral rSO2 in coronary artery bypass patients avoids profound cerebral desaturation and is associated with significantly fewer incidences of major organ dysfunctionâ&#x20AC;?
N= 100 intervention
Anesth Analg. 2007;104(1):51-58.
N=100 control (electronic blinding)
The percentage of serious desaturations was significantly greater in the control group Control Group • rSO2 AUC < 70% Baseline • > 150 min ∙ % • 6 patients
Study Group • rSO2 AUC < 70% Baseline • > 150 min ∙ % • none†
p < 0.014
2010 Avery ASA
†
Murkin JM, Adams SJ, Movick RJ, et al. Monitoring Brain Oxygen Saturation During Coronary Bypass Surgery: A Randomized, Prospective Study. Anesth Analg. 2007 Jan;104(1):51-58.
Overall % Efficacy of Interventions 80.4% 71% (40/56) required > 3 interventions
Murkin JM, Adams SJ, Movick RJ, et al. Monitoring Brain Oxygen Saturation During Coronary Bypass Surgery: A Randomized, Prospective Study. Anesth Analg. 2007 Jan;104(1):51-58.
5
• ICU length of stay for the intervention group was significantly shorter
Monitored Unmonitored
Days
4
2
1
• Standard deviation was also tighter, indicating fewer outlier patients
±2.7
3
±0.8 1.25
1.87
(p <0.029)
0
ICU Length of Stay Murkin JM, Adams SJ, Movick RJ, et al. Monitoring Brain Oxygen Saturation During Coronary Bypass Surgery: A Randomized, Prospective Study. Anesth Analg. 2007 Jan;104(1):51-58.
The 30-day major organ morbidity and mortality (MOMM) † was significantly lower in the study group (p < 0.048)
*p < 0.048 p < 0.017
§
†MOMM as defined by the STS; §CABG only § 2007 Anesth & Analg 104; 51
Reference
Title
Methods
Results
Conclusions
J Clin Anes 2005;17:426
A clinical evaluation of near cerebral oximetry in the awake patient to monitor cerebral perfusion during CEA
Prospective, observational study. Index – EEG, awake exam. N=50
Sensitivity 44% Specificity 82% NPV 94%
rSO2 correlates with clinical signs and EEG detected ischemia during CEA
S African J Surg 2007; 45:43
Cerebral monitoring during CEA-a comparison between EEG, transcranial cerebral oximetry and carotid stump pressure
Prospective, observational study Index-EEG, stump pressure N=100
Sensitivity 100% Specificity 87% NPV 100% PPV 33%
rSO2 has a high sensitivity but low specificity for ischemia during CEA when indexed against EEG. rSO2 changed prior to EEG change during ischemia.
J Vasc Surg 2008;48:601
Cerebral oximetry does not correlate with EEG and SSEP in determining the need for shunting during CEA
Prospective, observational study Index-EEG, SSEP N=323
Sensitivity 68% Specificity 94% NPV 98% PPV 47%
rSO2 should not be used as the sole monitor for ischemia during CEA. rSO2 does add information regarding cerebral ischemia when indexed against EEG and SSEP
Eur J Vasc Endovasc Surg 2011; 41; 606
The role of cerebral oximetry in combination with awake testing in patients undergoing CEA under local anaesthesia.
Prospective, observational study Index-awake exam N=100
Sensitivity 100% Specificity 96% NPV 100% PPV 81%
≥19% drop in rSO2 has a high sensitivity and specificity for detecting cerebral ischemia compared with awake exam
CEA–carotid endarterectomy; EEG-electroencephalogram; NPV-negative predictive value; PPV-positive predictive value; SSEP-somatosensory evoke potentials
• Previous clinical studies have indicated that cardiac surgery can be associated with an 33-83% incidence of postoperative neurocognitive dysfunction. ‡ • The association between physiologic variables representative of cerebral oxygenation (e.g., SjvO2) and neurocognitive outcomes was identified almost two decades ago.† • Recently, studies expanding on this work have demonstrated significant associations between perioperative NIRS rSO 2 values and postoperative neurocognitive dysfunction indicating a potential to mitigate these unfavorable outcomes by monitoring and treating observed perioperative cerebral desaturation. Tournay-Jette E, Dupuis G, Bherer L, et al. The relationship between cerebral oxygen saturation changes and postoperative cognitive dysfunction in elderly patients after coronary artery bypass graft surgery. J Cardiothor Vasc Anes 2011;25(1):95-104 † Croughwell ND, Newmann MF, Blumenthal JA, et al. Jugular bulb saturation and cognitive dysfunction after cardiopulmnary bypass. Ann Thorac Surg 1994; 58: 1702-8 ‡
Reference
Title
Methods
Results
Conclusion
J Cardio Thorac Vasc Anes 2004; 18: 552-8
Cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery
Prospective, observational ASEM and MMSE assessed NCD N=101
rSO2 < 40% an independent predictor of ↑ incidence of both ASEM & MMSE impairment
rSO2 desaturation is associated with early postoperative NCD in studied population
J Cardiothor Vasc Anes 2011; 25(1): 95-104
The relationship between cerebral oxygen saturation changes and postoperative cognitive dysfunction in elderly patients after coronary artery bypass graft surgery
Prospective, observational Full neuropsychological testing done Age > 65 years old N=61
rSO2 < 50% during surgery was associated with early NCD. rSO2 < 30% BL associated with late NCD
Intraoperative rSO2 desaturation is common (up to 80%) and associated with early & late NCD;
Ann Thorac Surg 2009; 87: 36-45
Cerebral oxygen desaturation predicts cognitive decline and longer hospital stay after cardiac surgery
Prospective, randomized, blinded, controlled standard NCD test battery N=265
AUC rSO2<50% > 3000 sec·% had greater risk of postoperative NCD & prolonged hospital stay (>6 d)
Intraoperative rSO2 desaturation is significantly associated with NCD and prolonged hospital stay
Crit Care 2011; 15: R218
Preoperative regional cerebral oxygen saturation is a predictor of postoperative delirium in on pump cardiac surgery patients: a prospective observational trial
Prospective, observational Delirium (CAM-ICU) and MMSE assessed NCD N=230
Lower preoperative rSO2 (< 59.5%) is an independent predictor of postoperative delirium
Low preoperative rSO2 is associated with postoperative delirium after on pump cardiac surgery
Brit J Anaesth 2012; 108(4): 623-9
Reduced cerebral oxygen saturation during thoracic surgery predicts early postoperative cognitive dysfunction
Prospective, observational in SLV thoracic procedures, MMSE assessed @3 & 24 hrs postop (FORESIGHT); N=76
↓rSO2 < 65% of BL occurred freq (60%); 29% of pts had ↓MMSE at 3hrs. ↓rSO2 <65% for even just 5 min assoc. w/↑OR 2.03 cognitive decline
Early cognitive dysfunction after SLV thoracic surgery is positively related to ↓intraop rSO2
ASEM-antisaccadic eye movement test; MMSE-mini-mental state examination; NCD-neurocognitive dysfunction; BL-baseline; CAM-ICU-confusion assessment method for the intensive care unit
Recently published data suggests that the room air baseline and oxygen supplemented rSO2 values may serve as a simple, noninvasive risk stratification tool for cardiac surgical patients providing useful insight into 30 day and 1 year mortality as well as the propensity for patients to develop postoperative delirium.
Heringlake M, Garbers C, Kabler J-H, et al. Preoperative Cerebral Oxygen Saturation and Clinical Outcomes in Cardiac Surgery. Anesthesiology. 2011; 114(1):58-69 Schoen J, Meyerrose J, Paarmann H, et al. Preoperative regional cerebral oxygen saturation is a predictor of postoperative delirium in on-pump cardiac sugery patients: a prospective observational trial. Critical Care 2011;15:R218
Prospective, observational pilot study n = 1,178 patients undergoing on-pump cardiac surgery in 2008 Preoperative determination of ScO2 (mostly on the ward) ScO2 when breathing room air ScO2 during oxygen supplementation (ScO2min-ox) -goal: SaO2 >98%
Concomitant determination of preoperative: – NTproBNP
- Hematocrit- EuroSCORE
– hsTNT - GFR
- LVEF class
Follow up including morbidity and mortality – Morbidity • > 1 major complications (LCOS, stroke, new RRT, reintubation) • and/or high dependency unit stay (ICU+ intermediate care) ≥ 10 days
– 30-day and 1-year mortality NTproBNP: N-terminal pro-B-type natriuetic peptide: high sensitivity troponin T; LCOS: low cardiac output syndrome; RRT: renal replacement therapy Heringlake M, Garbers C, Kabler J-H, et al. Preoperative Cerebral Oxygen Saturation and Clinical Outcomes in Cardiac Surgery. Anesthesiology. 2011; 114(1):58-69
ScO2min-ox competes with the EuroSCORE as a predictive index of 30-day mortality. mortality
AUC EuroSCORE 0.82† AUC ScO2min-ox 0.71 (rSO ≤51%) 2
(True+)
p=0.015 †
AUC EuroSCORE 0.54 AUC ScO2min-ox 0.77‡ (rSO ≤53%) 2
p=0.0044 ‡
(False+) Total Cohort
EuroSCORE > 10 Cohort
Heringlake M, Garbers C, Kabler J-H, et al. Preoperative Cerebral Oxygen Saturation and Clinical Outcomes in Cardiac Surgery. Anesthesiology. 2011; 114(1):58-69
ScO2min-ox â&#x2030;¤ 50% predicts 1 year mortality compared to ScO2min-ox > 50%
(days)
Total Cohort
EuroSCORE > 10 Cohort
Heringlake M, Garbers C, Kabler J-H, et al. Preoperative Cerebral Oxygen Saturation and Clinical Outcomes in Cardiac Surgery. Anesthesiology. 2011; 114(1):58-69
Anesth Analg 2010; 111:496-505
Miller MA, Dukkipati SR, Mittnacht AJ, et al. Activation and Entrainment Mapping of Hemodynamically Unstable Ventricular Tachycardia Using a Percutaneous Left Ventricular Assist Device . J Amer Coll Card 2011; 58:1363-71
frca.co.uk
Can J Anesth 2011; 58:986-92
Tang L, Kazan R, Taddei R, et al. British Journal of Anaesthesia 108 (4): 623â&#x20AC;&#x201C;9 (2012)
theuniversityhospital.com
2010 Avery NIRS White Paper Review www.casecag.com
ortho.umn.edu
Room air baseline established (strongly recommended) Oxygen supplemented baseline established (strongly recommended) 2 Strategies: – Maintain bilateral rSO2 values within 75% of established room air baseline – Maintain bilateral rSO2 values above 50% for patients with a baseline value of ≤ 50% Heringlake M, Garbers C, Kabler J-H, et al. Preoperative Cerebral Oxygen Saturation and Clinical Outcomes in Cardiac Surgery. Anesthesiology. 2011; 114(1):58-69 Botes K, LeRoux DA, VanMarle J. Cerebral Monitoring During Carotid Endarterectomy- A Comparison Between Electroencephalography, Transcranial Cerebral Oximetry and Carotid Stump Pressure. S Afr J Surg. 2007; 45(2):43-46 Kurihara K, Kukukawa A, Kobayashi A, Nakadate T. Frontal Cortical Oxygenation Changes During Gravity-Induced Loss of Consiousness in Humans: A Near-Infrared Spatially Resolved Spectroscopic Study. J Appl Physiol . 2007; 103:1326-1331 Kaminogo M, Ochi M, Onizuka M, Takahata H, Shibata S. An Additional Monitoring of Regaionl Cerebral Oxygen Saturation to HMPAO SPECT Study During Balloon Test Occlusion. Stroke. 1999; 30:407-413 Moritz S, Kasprzak P, Arlt M, Taeger K, Metz C. Accuracy of Cerebral Monitoring in Detecting Cerebral Ischemia During Carotid Endarterectomy. Anesthesiol. 2007; 107(4):563569
Mechanical Cause: –
Head position
–
Cannula position
Increase Supply (Oxygen Delivery): –
Increase blood pressure
–
Normalize CO2 to physiologic level
–
Increase FiO2
–
Increase cardiac output (pump flow)
–
Increase hematocrit
Decrease Demand (cerebral metabolism): –
Increase anesthetic depth
–
Decrease body temperature
-Yao FS, Levin SK, Woo D, et al. Maintaining Cerebral Oxygen Saturation During Cardiac Surgery Shortened ICU and Hospital Stays. J Cardiothorac Vasc Anesth 2004;18(5)5:552-558. -Denault A, Deschamps A, Murkin JM. A Proposed Algorithm for the Intraoperative Use of Cerebral Near-Infrared Spectroscopy. Sem Cardiothor Vasc Anesth. 2007: 11:274-281
Avery, EG
http://www.casecag.com/clinical%20protocols/Cerox_Clin_Prot_11-07-2011.pdf
www.casecag.com
HPI: 72 YO Polynesian ♀ with 2 vessel CAD s/f CABG x2 on CPB PMH: HTN, LVEF = 45% Ht = 4’ 8” Wt = 48 kg BSA = 1.38 Hct = 29%
Raping 400 mLs prior to CPB
CI 2.8 L/min/m2
ON CPB 75%BL L-BL 70% R-BL 64%
CI 2.6 L/min/m2
CI 1.4 L/min/m2 SBP 185 mmHg
Conclusions Clinicians challenged to maintain and/or improve upon clinical outcomes in aged NIRS is non-invasive and reveals regional tissue oxygen saturation (an index of tissue oxygen balance), in contrast to relying upon assumptions related to â&#x20AC;&#x153;acceptableâ&#x20AC;? physiologic parameters (e.g., MAP of 50-60 mmHg on CPB) Peer reviewed studies provide robust support of the idea that the INVOS rSO2 value represents an index of regional cerebral oxygen balance Published evidence supports the use of INVOS monitoring in Cardiac, Orthopedic, General, and Vascular surgery to alert the clinician to hypoperfusion and/or mechanical obstruction which may result in poor clinical outcomes
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No published peer reviewed manuscripts exist that compare the commercially available devices based upon the criteria that the FDA employed to provide device clearance (i.e. bias, precision and ARMS [average root mean squared]) However, non-peer review format data does exist Somanetics INVOS
CASMED – Fore-sight
2λ
Laser light
4λ
(~20 years of clinical use)
Nonin – Equanox Ornim – Cerox
3,4λ Ultrasound tagged NIR light
4λ
(2 models)
Comparison of Two Spatially Resolved NIRS Oxygenation Indices Gagnon RE, Macnab AJ, Gagnon FA, Blackstock D, LeBlance JG
CPB model with circulatory arrest N = 24 healthy juvenile swine
NIRO300
J Clin Monit Computing 2002;17:385-91
INVOS5100
Circulatory arrest
J Clin Monit Computing 2002;17:385-91
Comparison of Two Spatially Resolved NIRS Oxygenation Indices Gagnon RE, Macnab AJ, Gagnon FA, Blackstock D, LeBlance JG
Conclusions: There was close agreement between the INVOS and NIRO in response to major physiological change, although absolute values of (rSO2) and TOI were not identical. There was less agreement during baseline measurements or minimal physiologic change. Hence there does not appear to be any detectable benefit from the use of laser light sources and 2 additional wavelengths to determine tissue oxygen balance in various physiologic states J Clin Monit Computing 2002;17:385-91
Any unaccounted chromophore can reduce the optimal nature of rSO 2 Further, a chromophore sink also has a clear negative impact on the performance of all FDA cleared devices
N= 12
Anesthesiology 2012;116(4):834-40
Anesthesiology 2012;116(4):834-40
Anesthesiology 2012;116(4):834-40
Vein Shambles!
Phenylephrine for BP (anesthesiologist)
Perfusionist returning RAP volume
Thank you