Pressure reactivity: Relationship between ICP and arterial blood pressure (ABP). Pressure-reactivity index, computational methods. Clinical examples. Optimization of cerebral perfusion pressure: Relationship between Pressure Reactivity and CPP. Does optimal CPP exist always? Implications on management.
Simultaneous analysis of slow changes in arterial pressure and ICP System with disturbed pressurereactivity Pressurereactivity works properly
Thanks to Dr.P.Smielewski PRx- Calculation principles Input signals ICP, ABP Ouput trend PRx ABP 10 sec window 5 min window MAP Mean(ABP) Mean(ICP) MICP ICP Correlation(MAP, MICP) Primary analysis Final Analysis
PRx is a rather noisy parameter Some smoothing is required PRx Smoothed PRx Thanks to Dr.P.Smielewski
Intracranial Hypertension
Plateau Wave
Arterial Hypertension
CT Scan 1 Scan 2 SROR (CPP = 74 mmhg) (CPP = 98 mmhg) 5 60% 3 1 6 40% 2 4 20% 0.4 Figure 5: PET vs. PRx PRx 0.2 0.0-0.2-0.4 r 2 = 0.32 p = 0.02 (n = 17) PRx correlates with PET-static rate of autoregulation -0.6 0 20 40 60 80 100 120 140 Global SROR PET Steiner LA, Coles JP, Johnston AJ, Chatfield DA, Smielewski P, Fryer TD, Aigbirhio FI, Clark JC, Pickard JD, Menon DK, Czosnyka M. Assessment of Cerebrovascular Autoregulation in Head-Injured Patients. A Validation Study.Stroke. 2003 34:2404-2409
rcbf CMRO 2 OEF 0-30 ml/100g/min 0-100 m/100g/min 0-75 % 0.8 0.8 0.6 r 2 = 0.34 p = 0.0022 0.6 r 2 = 0.61 p < 0.00005 0.4 0.4 PRx 0.2 PRx 0.2 0.0 0.0-0.2-0.2-0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 global CMRO 2 (ml 100g -1 min -1 ) -0.4 24 30 36 42 48 54 60 Global oxygen extraction fraction (%)
FLUX ICP ABP PRx and the LLA ABP lowered to zero in piglet LDF vs. CPP to find lower limit of autoregulation PRx compared against LLA AUC=0.91!! Brady K, et al: Stroke 2008 Lee J, et al: Stroke 2009
LOOK at two Periods 1: PRX ~-1 and 2: PRx~+1 1 2
Individual trends are most important
Monitoring of Pressure Reactivity Index ICM+ software: www.neurosurg.cm.ac.uk/icmplus
Ups and downs... Final was not very optimistic
Deterioration of PRx precedes refractory intracranial hypertension?
Refractory intracranial hypertension (2) ABP mmhg ICP mmhg PRx CPP mmhg
Mortality rate dramatically depends on PRX
Optimal CPP- oriented therapy PRx PRx 50-50 55-55 55-55 60-60 60-60 65-65 65-65 70-70 70-70 75-75 75-75 80-80 80-80 85-85 85-85 90-90 90-90 95-95 95-95 100-100 100 100-105 - 105 Mx Both PRx and Mx show the U-shape relationship with mean CPP (200 patients!). This indicate that for low CPP and CPP above 90 mm Hg both autoregulation and pressure reactivity are defective. There is an optimal CPP from 70 to 90 mm Hg which helps to restore vascular functions after head injury.5.5.4.4.3.3.2.2.1.1 0.0 0.0 -.1 -.1 -.2 -.2 a.) a.) Optimal CPP Cerebral Perfusion Pressure (mm Hg) Cerebral Perfusion Pressure (mm Hg) Steiner LA at al. Continuous monitoring of cerebrovascular pressure reactivity allows determination of optimal cerebral perfusion pressure in patients with traumatic brain injury. Crit Care Med. 2002 Apr;30(4):733-8.
New results 2003-2009 Thanks to Dr. M.Aries
If we can see it in statistical evaluation of big series of patients, can we see it in individual cases? 4 6 hours moving window The chart shows that lowest PRx values corresponding to the strongest autoregulation level fall in the CPP range of 73-79 mmhg Thanks to Dr. P.Smielewski
Optimal CPP in individual cases Thanks to Dr.L.Steiner
Optimal CPP oriented therapy? CPPopt ADMISSION TO CRITICAL CARE UNIT START TREATMENT AT CPP 70 MM HG (OR HIGHER IN SEVERLY HEAD INJURED PATIENTS) MONITOR AND AVERAGE PRx FOR 2 HOURS Patient 1 IDENTIFY RANGE OF MINIMAL PRx BY VARYING CPP IN STEPS OF 10 mm Hg OVER 2 HOUR PERIODS 90 80 70 CPP OPT IDENTIFIED CALCULATE CPP OPT NO CPP OPT 60 0 24 48 72 96 120 Hours MINIMIZE CPP CPP OPT DURING THE FOLLOWING 2 HOURS MONITOR AND MINIMIZE PRx, POOL DATA AFTER 2 HOURS Steiner LA, Czosnyka M, Piechnik SK, Smielewski P, Chatfield D, Menon DK, Pickard JD. Continuous monitoring of cerebrovascular pressure reactivity allows determination of optimal cerebral perfusion pressure in patients with traumatic brain injury. Crit Care Med. 2002 Apr;30(4):733-8.
CPP OPT and Outcome r = -0.51 (Spearman rank test) p = 0.00001 Thanks to Dr. L.Steiner
CAMBRIDGE PROJECT: M.ARIES et al, 2010 Method Retrospective analysis (single centre) Data base 2003-2009 (n=327) TBI pts (GCS <8 in 80%) Continuous ICP/ABP monitoring (50 Hz) Glasgow outcome scale at 6 months Assumption: CPP optimal exists Narrow (one) CPP optimal range CPP optimal = the CPP at best cerebral vasoreactivity (pressure) autoregulation parameter: PRx - Correlation coefficient between ABP/ICP - CPP optimal= CPP at lowest PRx
Continuous assessment of CPPopt and real-time comparison with median CPP- 4 hours window
Optimal CPP as an individual threshold for CPP oriented therapy F value much greater than for set threshold
Rate of favourable outcome reaches maximum when CPP is close to optimal CPP For lower CPPs mortality increases For greater CPPs, rate of severe disability increases
CONCEPT CPPopt vs. standard CPP based pressure management Frankfurt 6. Mai 2012 IGNITE Jennifer Diedler Martin Schuhmann
In a meanwhile we are still doing observational studies: Refractory intracranial hypertension- red line again
Matchining Prx-CPP curve; only a left branch!
Road/work ahead.. (2) Large pooled TBI database Does the relation with outcome hold? Specific TBI pts benefit Edema/contusions DAI Target or Direction? Visual display of PRx/CPPopt (poster.) 19-9-2017 Thanks to Marcel Aries and Ari Ercole
Prx SAH: Effect of Vasospasm 0.8 0.6 0.4 SAH 0.2 0.0-0.2-0.4 30 40 50 60 70 80 90 100 110 120 CPP [mmhg] Thanks to Dr. P.Biljenga
What do we know so far about PRx in SAH? (statin trial, placebo branch). PRx agrees with Transient Hyperaemic Response Test and gets worse in vasospasm Tseng MY, Czosnyka M, Richards H, Pickard JD, Kirkpatrick PJ. Effects of acute treatment with pravastatin on cerebral vasospasm, autoregulation, and delayed ischemic deficits after aneurysmal subarachnoid hemorrhage: a phase II randomized placebo-controlled trial. Stroke. 2005 Aug;36(8):1627-32.
Summary Simple analysis of ABP-ICP interaction (low bandwidth) Positive association with outcome Detection of optimal CPP Good agreement with other more expensive methods Promising value of PRx after SAH