CPB pump flow, and effective Flow in patient. 1

Transcription

1 Peter Fast Nielsen ECCP, MCT AUH. Skejby, Denmark. CPB pump flow, and effective Flow in patient. 1 Pump Flow - that s what the Perfusionist controls, right? Well: Does the pump deliver what we expect? Is pump flow the same as CO? What is the effective Flow? Loss from shunts in circuit Shunts in patient 2 Roller pump Estimated flow from RPM 3 1

2 Actual pumpflow depends upon: RPM Raceway Stroke volume Occlusion setting Tube Fluid (viscosity) Pre- and afterload Correct calibration 4 5 Occlusion settings Hard: Descent rate< 0-1 cm/mi 5 RPM against occlusion > 350 mmhg Medium: Descent rate 2-3 cm/min 5 RPM against occlusion mmhg Light: Descent rate 4-10 cm/min 5 RPM against occlusion mmhg 6 2

3 Percentage flow Preload - Afterload Low preload causes: VAVD Constriction (3/8 ) Kink of pump inlet (Mayo report: down to 45%) High afterload causes: Oxygenator Tubing A-filter A-cannula Kinking 7 Pre- and afterload Flow vs Preload Flow vs Afterload 2% loss 120% 100% 100% 80% 80% 2% loss Soft occlusion Hard occlusion 60% 40% 60% 40% Hard occlusion Medium occlusion Soft occlusion 20% 20% 0% Preload pressure 0% Calibration of Pump Measure flow - with realistic pre- and afterload Dependent of tubing Standardized occlusion 9 3

4 Flow at roller pump 6 Flow (L/min) Pulsation? 11 Effective FLOW Loosing flow after pump: Internal shunts from oxygenator External shunts in circuit Shunts in/from patient 12 4

5 Shunts Oxygenator CTR A-filter CTR (sample) A-line V-line Hemofilter Blood CPL 13 Calculated flow in blood at specified pressure difference in 1 m tubing (Darcy-Weisbach-Mod.1) Diam. (Inch) Diam. (mm) Flow at 20 mmhg Flow at 50 mmhg Flow at 100 mmhg Flow at 200 mmhg Flow at 400 mmhg 1/16 (sample) 1, Sample line 2, Sample line 2, /8 3, /16 4, /4 6, /16 2, /8 9, /2 12, Sample line "Stolen" blood flow: effect of an open arterial filter purge line in a simulated neonatal CPB model. Wang S, Department of Pediatrics, Penn State College Medicine, Penn State Children's Hospital, Hershey, Pennsylvania , USA. Sample line open. Pressure 180mmHg. Flow 0,6 L/min: Loosing 26% of flow Flow 0,2 L/min: Loosing 83% of flow! 15 5

6 Perfusion May;26(3): Epub 2011 Jan 31. Evaluation of shunting flow differences in varied conditions in a simulated adult CPB model during normothermia. Duan X, Ji B, Liu G, Li Q, Liu J, Yu K, Tang Y, Long C. Fuwai Hospital & Cardiovascular Institute, Peking 3/16 purge line and ¼ hemofilter 16 Shunts Sampel line Flow Left To The Patient of 5000 ml/min Flow in arterial line 4750 ml/min 3/ ml/min 3/16 + sampel line 3800 ml/min 1/4 + sampel line 1000 ml /min 1/4 + 3/ ml / min All 400 ml / min Christoffer Hansson & Daniel Johagen 17 Shunts in patient Venting of arterial blood - in peds: easily over 50% of flow. Bleeding/suction of arterial blood Physiological shunts (a-v) Anatomic abnormalities Uneven distribution 18 6

7 Physiological shunts in circulation Uneven distribution - Especially in Digestion system Inner/outer circle Makes svo2 unreliable - if high 19 Each organ adds to resistance, - or shunting 20 Organ distribution Distribution of Cardiac Output to Body Organs (resting) Organ relative to Body weight Blood Flow (ml/min) Organ flow relative to CO Brain 2.0 % % 46 Heart 0.43 % % 23 Kidneys 0.43 % % 18 GI - Liver 2.1 % % 66 Lung 1.5 % % 5 Muscle 39.7 % % (64) Rest 55.3 % % 33 O 2 consumption (ml/min) 21 7

8 FLOW evaluation Adjustments according to: Blood pressure SvO 2 BE Lactate Diuresis 22 Flow measurement Calculations from RPM Bucket and stop watch. Ultrasound, Transit Time Conductivity Accuracy? 23 Conclusions Perfusionist has not complete control! Pump flow CO Beware of shunts combined with high pressure and low flow (peds) Arterial line flow should be measured Clinical assessment of sufficient flow 24 8

9 25 How much flow does the patient need? Oxygen delivery Flow Hct Sat Consumption Adjustments to: Age BMI Muscle/fat Sex Temperature VO 2 Q x [Hgb] x (SaO 2 - SvO 2 ) 26 Calculate EBF EBF in adults: x BSA (L/min/m ) 2 EBF in pediatrics: x BSA EBF from weight alone: <3kg: 200 ml/kg/min 3-10kg: 150 ml/kg/min 10-15kg: 125 ml/kg/min 15-30kg: 100 ml/kg/min 30-55kg: 75 ml/kg/min 55-75kg: 65 ml/kg/min kg: 60 ml/kg/min >100kg: 50 ml/kg/min 27 9

10 BSA Calculations Dubois: x Height(m) x Weight(kg) Mosteller: ( [Height(cm) x Weight(kg) ]/ 3600 ) ½ New (weight) BSA = (4xW+7) / (90+W) Simple estimate: (H + W - 60 ) /100 Even more simple (adults): W / Proportional to CO? 002 Dubois Mosteller 001 Simpel W-only W(65ml/kg) Flow vs Temperature Temperature ( o C) Metabolism Min. Flow/BSA Max. Arrest % min % min % min % min % min 10 7 % min 30 10

11 Optimal Perfusion During Cardiopulmonary Bypass: An Evidence-Based Approach Glenn S. Murphy, MD*, Eugene A. Hessel II, MD and Robert C. Groom, MS, CCP 31 11