NIRS of the brain new diagnostic tool

Transcription

1 NIRS of the brain new diagnostic tool Berndt Urlesberger Professor of Neonatology Head, Division of Neonatology, Department of Pediatrics Medical University Graz, Austria Medizinische Universität Graz, Universitätsplatz 3, A-8010 Graz, Topics! Basic principles! What is rsto2?! Cerebral application! Clinical use 1

2 Basic Principles of NIRS! Nearinfrared light can propagate through tissues and, at particular wavelengths, is differentially absorbed by oxygenated vs. deoxygenated hemoglobin (HbO2, Hb) and myoglobin.! Both oxygenated and deoxygenated forms absorb light at 800nm, whereas at 760nm absorption is primarily by deoxygenated forms.! The contribution of myoglobin to the signal is assumed to be 10% or less.! Myoglobin should be fully saturated under most conditions, as the P 50 for myoglobin is very low (5mmHg). NIRS Devices - Wavelength NIRO 200, Hamamatsu INVOS, Somanetics Fore Sight, Casmed Wavelengths : Equanox, Nonin NIRO 200: 775, 810, 850 nm INVOS: 730, 810 nm Fore Sight: 690, 780, 805, 850 nm Equanox: 730, 760, 810, 880 2

3 NIRS-Parameters Where do we measure?! Contribution of vessels All vessels with a diameter below 0.1mm contribute to signal! (1,2) Hypothesis of involved compartments arteriolar 10% (5%) capillary 20% (20%) venular 70% (75%) 1 Mancini D et al, J Appl Physiol : Firebank M, et al, J Appl Physiol :1915 Is the involved compartment relevant? YES! Compartment represents huge part of vascular bed! Tsai AG et al, Physiol Rev 2003, 83:93 3

4 Spatially Resolved Spectroscopy 1 One emission probe. Multiple Sensors. The slope of light attenuation versus distance allows calculation of absolute saturation value: Regional Oxygen Tissue Saturation (rsto2) Superficial tissue is subtracted. Thus regional oxygen saturation relates more to aimed tissue compartment. Measurment depth is half the distance of sensor and emittor 1 Suzuki S, et al. Proc SPIE 1999;3597: What is rsto2?! It reflects the balance between regional oxygen delivery and consumption within a tissue compartment. No differentiation of tissue layers!!! Absolute parameter!! Arterial:venous proportion = 25:75 4

5 What is rsto2? Regionale Balance zwischen Sauerstoff- Anlieferung und -Verbrauch (Oxygen Delivery vs Oxygen Consumption) Simplification! Gefäße sind erst unter einem Durchmesser von 100microm involviert! Anteile Arterie:Kapillare:Vene = 20:5:75 Arteriell:venös = 25:75! Thus rsto2 is closer to SvO2 than SaO2.! But rsto2 does not represent/equate SvO2!!!! SvO2 and rsto2 do not always parallel each other! Comparison Tissue compartment vs Venous drainage Tissue compartment vs Venous drainage 5

6 Absolute normal values for rsto2 (brain)? < > 85 Kurth et al, J Cereb Blood Flow Metab 2002 Are there clinical data supporting this? Adult patients after cardiac arrest. Neurologic Outcome in relation to rcso2 at admission. Regional cerebral oxygen saturation on hospital arrival is a potential novel predictor of neurological outcomes at hospital discharge in patients with out-of-hospital cardiac arrest Ito N. et al, Resuscitation Volume 83, Issue

7 Comparability of devices? NIRO 200, Hamamatsu INVOS, Somanetics Problem: No Goldstandard! Equanox, Nonin Fore Sight, Casmed All devices measure reliable. But there are differences which may be of interest during clinical use. The Sensor-Problem! Keep an eye on the sensor, you use! Dullenkopf et al, Paediatric Anaesthesia

8 NIRS Devices Differences in rsto2 values Mean Normal Values A) INVOS adult 70% B) INVOS neonatal 80% linear regression r=0.89: AB C) Fore-Sight neonatal 81% linear regression r=0.74:ac D) Equanox adult 65% linear regression r=0.62:cd Dix L, et al, Pediatr Res 2013 Decives are calibrated differently?! Witzner Hessel T, et al, Acta Pediatrica

9 Clinical application of NIRS Cerebral Measurements! Pubmed: NIRS cerebral: 1906 publications! Most of them are observational studies! Does the use of NIRS improve outcome in neonatal patients?! Clinical Question: Needs randomised trials 85% 55% A Phase II trial to test the hypothesis that the burden of hypoxia and hyperoxia could be reduced by the combination of cerebral NIRS monitoring and a dedicated treatment guideline and to demonstrate the feasibility of such an approach. 9

10 Next Step: To show in Phase III Multicenter RCT, that this improves neonatal outcome. SafeBoosC Treatment Protocol rsto 2 < 55% rsto 2 > 85% Clinical assessment Blood Pressure CRT Lactate Consider volume expansion, vasopressor/inotropes, decrease MAP On vasopressors? Cardiovascular status Urine output Consider reducing vasopressor Echocardiography Low CO/ SVC flow PDA Consider volume expansion, inotropes, decrease MAP Consider treatment Oxygen transport [Hb] low Consider RBC transfusion Respiratory status SaO 2 low PCO 2 low Consider increase FiO 2 Consider decrease MV Consider decrease FiO 2 Consider increase MV SaO 2 high PCO 2 high Respiratory status Consider increase glucose intake Low Blood glucose level 10

11 Clinical application of NIRS Cerebral measurements in term infants rsto 2 of the brain in newborns with severe asphyxia adverse outcome good outcome From 24 hours onward, the values of FTOE of the infants with an adverse outcome were significantly lower as compared with those with a favorable outcome. But course of rsto 2 had only predictional value at the group level, not at an individual level. Toet MC et al, Pediatrics 2006, 117:333 11

12 NIRS Device:! INVOS 4100! adult sensor!!! If you compare rsto2 data to neonatal sensor : -10%!!!! Use adult sensor in asphyctic newborns! Toet MC et al, Pediatrics 2006, 117:333 Impaired cerebral autoregulation: rso2 and MABP Wong F et al, Pediatrics

13 Impaired cerebral autoregulation: rso2 and MABP Autoregulation impaired Autoregulation functioning Wong F et al, Pediatrics 2008 rsto2 during neonatal transition 13

14 rsto2 during neonatal transition INVOS 5100 Pichler G, et al, J Pediatr 2013; 163:1558 rsto2 druing neonatal transition NIRO 200NX Baik N et al, Neonatology 2015; 108:283 14

15 rsto2 during neonatal transition INVOS 5100 NIRO 200NX Pichler G, et al, J Pediatr 2013; 163:1558 Baik N et al, Neonatology 2015; 108:283 NIRS visible NIRS not visible rsto2, 10 th percentile Pichler et al, submitted 15

16 Infants without IVH 10th Percentile Infants developed IVH later on Conclusion! NIRS is a promising tool since 1997.! There are >1000 observational studies using cerebral NIRS.! But in 2015, the first RCT (SafeBoosC, phase II trial) proved, that it is feasible to reduce burden of cerebral hypoxia/hyperoxia in preterm infants with the use of NIRS in combination with treatment protocol.! At the moment, this treatment protocol is the best approach available.! In order to have adequate evidence for the positive effects of NIRS within clinical routine more RCTs are needed. 16

17 Research Unit for Cerebral Development and Oximetry Division of Neonatology, Medical University Graz, Austria Gerhard Pichler Corinna Binder Heschl Nariae Baik Bernhard Schwaberger Mirjam Pocivalnik Evelyn Ziehenberger Lukas Mileder Thomas Freidl Thank you for your attention! Medizinische Universität Graz, Universitätsplatz 3, A-8010 Graz, 17