Oxygen Supply and Demand in Critical Illness Edward M. Omron MD, MPH, FCCP Critical Care Services
Objectives <ul><li>Is oxygen delivery adequate for the patient? </li></ul><ul><li>Is cardiac output adequate for oxygen co...
 
 
 
 
 
 
 
 
 
 
Oxygen Demand, Consumption, and Delivery Oxygen Demand:  The amount of oxygen needed to satisfy the metabolic requirements...
Oxygen Demand, Consumption, and Delivery Physiologic stress states: Infection, Surgery, and Trauma Oxygen Demand exceeds d...
Cardinal Rules of Critical Care <ul><li>Golden Hour </li></ul><ul><ul><ul><li>Early correction of oxygen debt prevents mul...
<ul><li>Cardinal Rules of Critical Care </li></ul><ul><ul><li>1.  GOLDEN HOUR  </li></ul></ul><ul><ul><ul><li>Time depende...
Golden Hour <ul><li>Survival  Time To Treatment </li></ul><ul><li>Vietnam War  97.5%  1 hours </li></ul><ul><li>Korean War...
GOLDEN HOUR <ul><li>Shoemaker, WC </li></ul><ul><ul><li>Chest  1988;94:1187-1195 </li></ul></ul><ul><ul><li>Prospective tr...
GOLDEN HOUR <ul><li>Rivers, Emmanual </li></ul><ul><ul><li>NEJM  2001; 345: 1368-1377 </li></ul></ul><ul><ul><li>Early goa...
Components of Oxygen Delivery <ul><li>DO 2  (oxygen delivery in mL O 2 /min) </li></ul><ul><li>DO 2  = CO x CaO 2  x10  </...
Effects of PaO 2 , Hemoglobin, cardiac output on DO 2  (oxygen delivery) <ul><li>FiO 2   PaO 2   SaO 2   Hb  (g/dL)   C.O....
<ul><li>Preload Augmentation </li></ul><ul><li>DO 2  (oxygen delivery in mL O 2 /min) </li></ul><ul><li>DO 2  = CO x CaO 2...
Stroke Volume Cardiac Output Venous Return RAP, Preload or RV End diastolic Volume Starling Curve Volume Responsive Volume...
Preload Augmentation s/p fluid bolus Preload RESPONSIVE RAP RVEDV  Cardiac Output Normal Abnormal (Cardiogenic or septic s...
Preload Augmentation s/p fluid bolus Preload UNRESPONSIVE RVEDV or LVEDV Stroke Volume Normal Abnormal (Cardiogenic or sep...
. Stroke volume Ventricular preload Starling Curve <ul><li>Leg Raise </li></ul><ul><li>PP Variation </li></ul><ul><li>PCO2...
Cardinal Rules of Critical Care <ul><ul><li>2. Maximize Oxygen Delivery </li></ul></ul><ul><ul><ul><li>Improve Cardiac Per...
VO 2  or Oxygen Consumption <ul><li>VO 2  = Arterial O 2  delivery – Venous O 2  delivery </li></ul><ul><li>The difference...
 
Fick Equation for Oxygen Consumption <ul><li>V O 2 = Oxygen Consumption (250 mL/min) </li></ul><ul><li>V O 2  = 10*C.O.*(C...
Four Determinants of Mixed Venous Oximetry SvO 2  = SaO 2  - (VO 2  / C.O. x Hgb x 1.34) SvO 2   = Mixed venous saturation...
 
 
Why measure SvO2? <ul><li>A decrease in SvO2 is an early indicator of a threat to tissue oxygenation </li></ul><ul><li>Ear...
PaO 2  vs PvO 2   in Cardiogenic Shock Arterial Venous Saturation Difference SHOCK
 
Master Equation ScvO2     SvO2 = SaO2  - (VO2 / C.O. x Hgb x 1.34) <ul><li>Acute Illness or Post-op Surgery </li></ul><ul...
Cardinal Rules of Critical Care <ul><ul><li>3. Minimize oxygen consumption </li></ul></ul><ul><ul><ul><li>Sedation, analge...
Is cardiac output adequate for oxygen consumption? <ul><li>Mixed or central venous PCO2 gradient is proportional to 1/Card...
Paradoxical Respiratory Acidosis of Cardiopulmonary Arrest Venous Arterial CO2 Difference Cardiogenic Shock
Central Venous-Arterial PCO2 Gradient
Fick Equation for CO 2  production <ul><li>V CO2  =Carbon dioxide production (200 mL/min) </li></ul><ul><li>V CO2  = 10*C....
 
<ul><li>65 year old man presents to the ER in Shock </li></ul><ul><ul><li>BP 60/30, HR 150 bpm </li></ul></ul><ul><ul><li>...
Two Possible Causes of the Low Blood Pressure were Considered <ul><li>Cardiogenic Shock </li></ul><ul><li>Hemorrhagic Shoc...
Match the ABG VBG with the Associated Condition ( a) pH = 7.25, PCO2 =  30 , PaO2 = 75, saturation =  97%,  BE = -15, LA =...
Endpoints of Resuscitation <ul><li>50% of critically ill patients who present in shock who were resuscitated to normal vit...
Endpoint of Resuscitation <ul><li>Conventional Endpoints are lagging indicators of inadequate oxygen delivery </li></ul><u...
<ul><li>More effective endpoints of resuscitation </li></ul><ul><ul><ul><li>Continuous Cardiac Index </li></ul></ul></ul><...
Resuscitation Endpoints <ul><li>A single set of data points is useless </li></ul><ul><ul><li>C.I., SvO2, PaCO2-PvCO2, SBE,...
Systolic Pressure Variation
SEPTIC SHOCK PRESENT SBP ≤ 90 mmHg  or  MAP ≤ 65 mmHg OR Lactate  ≥ 4 mmol/L PLUS Clinical Picture c/w Infection Fluid bol...
 
 
 
 
 
Benefits of EGDT <ul><li>$12,000.00 reduction in total hospital charges </li></ul><ul><li>34% reduction in sepsis mortalit...
References <ul><li>Chest 2005;128:554s-560s </li></ul><ul><li>Chest 2006; 130: 1579-1595 </li></ul><ul><li>Intensive Care ...
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Oxygen delivery and consumption in critical care

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Discussion of oxygen delivery and consumption principles in critical illness with the golden rules of resuscitation
Edward Omron MD, MPH, FCCP
Pulmonary, Critical Care, and Internal Medicine
Morgan Hill, CA 95037

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  • Excellent overview - Thank you! You highlight many important points, including the need for dynamic and real-time measures of flow (CO/CI) and the balance of tissue oxygenation (ScvO2) in determining adequate resuscitation.
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  • wow thank you so much from venezuela im an icu resident
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Oxygen delivery and consumption in critical care

  1. 1. Oxygen Supply and Demand in Critical Illness Edward M. Omron MD, MPH, FCCP Critical Care Services
  2. 2. Objectives <ul><li>Is oxygen delivery adequate for the patient? </li></ul><ul><li>Is cardiac output adequate for oxygen consumption? </li></ul><ul><li>Is oxygen consumption adequate for oxygen demand? </li></ul>
  3. 13. Oxygen Demand, Consumption, and Delivery Oxygen Demand: The amount of oxygen needed to satisfy the metabolic requirements of all body tissues. Determined by physiologic stress, infection, temperature, and is coupled to cardiac output and minute ventilation Oxygen Consumption: Amount of oxygen used and made available to the body tissues
  4. 14. Oxygen Demand, Consumption, and Delivery Physiologic stress states: Infection, Surgery, and Trauma Oxygen Demand exceeds delivery and occult or frank shock may be present Anaerobic metabolism Lactic acidosis Cell Injury Cell Death
  5. 15. Cardinal Rules of Critical Care <ul><li>Golden Hour </li></ul><ul><ul><ul><li>Early correction of oxygen debt prevents multi-organ failure that leads to death </li></ul></ul></ul><ul><li>Maximize oxygen delivery </li></ul><ul><ul><ul><li>The supply of oxygen to the tissues must always exceed demand </li></ul></ul></ul><ul><li>Minimize oxygen consumption </li></ul><ul><ul><ul><li>Shock: oxygen demand exceeds supply </li></ul></ul></ul><ul><ul><ul><li>Global tissue hypoxia, anaerobic metabolism, lactic acidosis and cell death. </li></ul></ul></ul>
  6. 16. <ul><li>Cardinal Rules of Critical Care </li></ul><ul><ul><li>1. GOLDEN HOUR </li></ul></ul><ul><ul><ul><li>Time dependent function </li></ul></ul></ul><ul><li>Early correction of oxygen debt prevents multi-organ failure that leads to death </li></ul><ul><li>In World War I, there was an appreciation of time between wounding and shock treatment. If the patient was treated within one hour, mortality was 10%; and, after eight hours the mortality was 75%. </li></ul>
  7. 17. Golden Hour <ul><li>Survival Time To Treatment </li></ul><ul><li>Vietnam War 97.5% 1 hours </li></ul><ul><li>Korean War 95.5% 5 hours </li></ul><ul><li>World War 2 95.5% 10 hours </li></ul><ul><li>Regarding penetrating torso injuries </li></ul><ul><li>Medical success was attributed to helicopter evacuation, whole blood, medical teams, and forward hospitals </li></ul><ul><li>Not really a “Golden Hour” but a term used to indicate urgency of care and the crucial importance of time </li></ul><ul><li>Ann Emerg Med 1981; 10: 659-661 </li></ul><ul><li>Acad Emerg Med 2001; 8: 758-760 </li></ul>
  8. 18. GOLDEN HOUR <ul><li>Shoemaker, WC </li></ul><ul><ul><li>Chest 1988;94:1187-1195 </li></ul></ul><ul><ul><li>Prospective trial of early goal-directed therapy in high risk surgical patients </li></ul></ul><ul><ul><li>Marked improvement in mortality in experimental groups that received early pre-operative and perioperative optimization of oxygen transport variables </li></ul></ul>
  9. 19. GOLDEN HOUR <ul><li>Rivers, Emmanual </li></ul><ul><ul><li>NEJM 2001; 345: 1368-1377 </li></ul></ul><ul><ul><li>Early goal-directed therapy in severe sepsis and septic shock during the first 6 hours after presentation </li></ul></ul><ul><ul><li>Significant reductions in mortality, morbidity in experimental group that optimized oxygen delivery and consumption variables </li></ul></ul>
  10. 20. Components of Oxygen Delivery <ul><li>DO 2 (oxygen delivery in mL O 2 /min) </li></ul><ul><li>DO 2 = CO x CaO 2 x10 </li></ul><ul><li>DO 2 = (HR x SV) x CaO 2 x10 </li></ul><ul><li>DO 2 =(HR x SV)x(1.34 x Hb x SaO 2 )x10 </li></ul>
  11. 21. Effects of PaO 2 , Hemoglobin, cardiac output on DO 2 (oxygen delivery) <ul><li>FiO 2 PaO 2 SaO 2 Hb (g/dL) C.O. (l/min) DO 2 % </li></ul><ul><li>0.21 70 96% 13 5.3 900 0 </li></ul><ul><li>0.21 45 75% 7 4 288 -68 </li></ul><ul><li>0.60 350 98% 7 4 384 +25 </li></ul><ul><li>0.60 350 98% 10.5 4 568 +48 </li></ul><ul><li>0.60 350 98% 10.5 6 852 +50 </li></ul>
  12. 22. <ul><li>Preload Augmentation </li></ul><ul><li>DO 2 (oxygen delivery in mL O 2 /min) </li></ul><ul><li>DO 2 = CO x CaO 2 x 10 </li></ul><ul><li>DO 2 = HR x SV x CaO 2 x 10 </li></ul><ul><li>DO 2 = HR x SV x Hb x SaO 2 x 13.8 </li></ul>
  13. 23. Stroke Volume Cardiac Output Venous Return RAP, Preload or RV End diastolic Volume Starling Curve Volume Responsive Volume Unresponsive preload-dependence preload-independence
  14. 24. Preload Augmentation s/p fluid bolus Preload RESPONSIVE RAP RVEDV Cardiac Output Normal Abnormal (Cardiogenic or septic shock) 50 mL 100 mL 150 mL 200 mL
  15. 25. Preload Augmentation s/p fluid bolus Preload UNRESPONSIVE RVEDV or LVEDV Stroke Volume Normal Abnormal (Cardiogenic or septic shock) 50 mL 100 mL 150 mL 200 mL
  16. 26. . Stroke volume Ventricular preload Starling Curve <ul><li>Leg Raise </li></ul><ul><li>PP Variation </li></ul><ul><li>PCO2 </li></ul><ul><li>TTE </li></ul><ul><li>SVO2 </li></ul><ul><li>CCI </li></ul><ul><li>CEDV? </li></ul>normal heart failing heart preload-dependence preload-independence
  17. 27. Cardinal Rules of Critical Care <ul><ul><li>2. Maximize Oxygen Delivery </li></ul></ul><ul><ul><ul><li>Improve Cardiac Performance </li></ul></ul></ul><ul><ul><ul><ul><li>Maintain MAP > 65 mm Hg (arbitrary) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Preload Augmentation (crystalloid/colloid) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Inotropes (norepinephrine) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Peripheral vasoconstrictor (vasopressin) </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Transfuse Packed Red Blood Cells </li></ul></ul></ul><ul><ul><ul><li>Assume control of ventilation/oxygenation </li></ul></ul></ul><ul><ul><ul><ul><li>FIO 2 factors </li></ul></ul></ul></ul>
  18. 28. VO 2 or Oxygen Consumption <ul><li>VO 2 = Arterial O 2 delivery – Venous O 2 delivery </li></ul><ul><li>The difference represents the amount of oxygen consumed by the tissues </li></ul><ul><li>Normal = 250 mL/min or 5 mL/100 mL blood </li></ul>
  19. 30. Fick Equation for Oxygen Consumption <ul><li>V O 2 = Oxygen Consumption (250 mL/min) </li></ul><ul><li>V O 2 = 10*C.O.*(CaO2 –CvO2) </li></ul><ul><li>V O 2 = 10 * C.O. * (1.34*Hgn*SaO2 -1.34*Hgn*SvO2) </li></ul><ul><li>V O 2 = 1.34*Hgn*10*C.O.*(SaO 2 – SvO 2 ) </li></ul><ul><li>Solve for SvO 2 ? Or the mixed venous saturation? </li></ul>
  20. 31. Four Determinants of Mixed Venous Oximetry SvO 2 = SaO 2 - (VO 2 / C.O. x Hgb x 1.34) SvO 2 = Mixed venous saturation (%) SaO 2 = Arterial oxygen saturation (%) VO 2 = Oxygen consumption mL (O 2 /min) Hgb = Hemoglobin concentration (g/dL) Cardiac Output (C.O.) = dL/min
  21. 34. Why measure SvO2? <ul><li>A decrease in SvO2 is an early indicator of a threat to tissue oxygenation </li></ul><ul><li>Earlier information results in earlier diagnosis with interventions </li></ul><ul><li>Normal range of SvO2 = 60-80% </li></ul><ul><li>The 5 th vital sign </li></ul>
  22. 35. PaO 2 vs PvO 2 in Cardiogenic Shock Arterial Venous Saturation Difference SHOCK
  23. 37. Master Equation ScvO2  SvO2 = SaO2 - (VO2 / C.O. x Hgb x 1.34) <ul><li>Acute Illness or Post-op Surgery </li></ul><ul><ul><li>SaO 2 , VO 2 , Cardiac Output, and Hgb are dynamically changing concurrently </li></ul></ul><ul><ul><li>Optimize each parameter then recheck ScvO 2 to assess response to intervention </li></ul></ul>
  24. 38. Cardinal Rules of Critical Care <ul><ul><li>3. Minimize oxygen consumption </li></ul></ul><ul><ul><ul><li>Sedation, analgesia, rarely neuromuscular blockade </li></ul></ul></ul><ul><ul><ul><li>Work of breathing </li></ul></ul></ul><ul><ul><ul><li>Fever </li></ul></ul></ul><ul><ul><ul><li>Rigors </li></ul></ul></ul><ul><ul><ul><li>Pain </li></ul></ul></ul><ul><ul><ul><li>Anxiety </li></ul></ul></ul>
  25. 39. Is cardiac output adequate for oxygen consumption? <ul><li>Mixed or central venous PCO2 gradient is proportional to 1/Cardiac index </li></ul><ul><li>Tissue hypercarbic acidosis evolves during ischemic hypoxia or low flow states </li></ul><ul><li>Oxygen utilization coefficient > 35% as well </li></ul>
  26. 40. Paradoxical Respiratory Acidosis of Cardiopulmonary Arrest Venous Arterial CO2 Difference Cardiogenic Shock
  27. 41. Central Venous-Arterial PCO2 Gradient
  28. 42. Fick Equation for CO 2 production <ul><li>V CO2 =Carbon dioxide production (200 mL/min) </li></ul><ul><li>V CO2 = 10*C.O.*(PvCO 2 – PaCO 2 ) </li></ul><ul><li>If cardiac output decreases and V CO2 remains constant, what must happen to venous-arterial CO2 difference? </li></ul><ul><li>V CO2 = 10* C.O.* (PvCO 2 – PaCO 2 ) </li></ul>
  29. 44. <ul><li>65 year old man presents to the ER in Shock </li></ul><ul><ul><li>BP 60/30, HR 150 bpm </li></ul></ul><ul><ul><li>Paleness </li></ul></ul><ul><ul><li>Cool Skin </li></ul></ul><ul><ul><li>Dilated Pupils </li></ul></ul><ul><ul><li>Semicomatose state </li></ul></ul><ul><ul><li>Low Urine Output </li></ul></ul>
  30. 45. Two Possible Causes of the Low Blood Pressure were Considered <ul><li>Cardiogenic Shock </li></ul><ul><li>Hemorrhagic Shock </li></ul>
  31. 46. Match the ABG VBG with the Associated Condition ( a) pH = 7.25, PCO2 = 30 , PaO2 = 75, saturation = 97%, BE = -15, LA = -15 (v) pH = 7.20, PCO2 = 36 , PvO2 = 25, venous saturation = 45% (a) pH = 7.30, PCO2 = 25 , PaO2 50, BE = -10, saturation = 85 % LA = -10 (v) pH = 7.20, PCO2 = 50 , PvO2 = 25, venous saturation = 45 %
  32. 47. Endpoints of Resuscitation <ul><li>50% of critically ill patients who present in shock who were resuscitated to normal vital signs continued to have increased lactate and low SvO2 and ScvO2 </li></ul>
  33. 48. Endpoint of Resuscitation <ul><li>Conventional Endpoints are lagging indicators of inadequate oxygen delivery </li></ul><ul><ul><li>Blood Pressure </li></ul></ul><ul><ul><li>Heart Rate </li></ul></ul><ul><ul><li>Urine Output </li></ul></ul><ul><ul><li>Mental Status Changes </li></ul></ul><ul><ul><li>Central Venous Pressure (poor surrogate of filling pressures) </li></ul></ul>
  34. 49. <ul><li>More effective endpoints of resuscitation </li></ul><ul><ul><ul><li>Continuous Cardiac Index </li></ul></ul></ul><ul><ul><ul><ul><li>Pulse pressure variation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Systolic pressure variation </li></ul></ul></ul></ul><ul><ul><ul><li>SvO2 or ScvO2 </li></ul></ul></ul><ul><ul><ul><li>Serum lactate (Tissue hypoxia) </li></ul></ul></ul><ul><ul><ul><li>Venous – arterial PCO2 </li></ul></ul></ul><ul><ul><ul><ul><li>Directly correlates with cardiac index </li></ul></ul></ul></ul><ul><ul><ul><li>Metabolic acid-base status (SBE) </li></ul></ul></ul><ul><ul><ul><li>With CVP </li></ul></ul></ul>
  35. 50. Resuscitation Endpoints <ul><li>A single set of data points is useless </li></ul><ul><ul><li>C.I., SvO2, PaCO2-PvCO2, SBE, Lactate </li></ul></ul><ul><li>Construct multiple data points to assess trends and response to interventions! </li></ul><ul><li>REAL time bedside interventions </li></ul>
  36. 51. Systolic Pressure Variation
  37. 52. SEPTIC SHOCK PRESENT SBP ≤ 90 mmHg or MAP ≤ 65 mmHg OR Lactate ≥ 4 mmol/L PLUS Clinical Picture c/w Infection Fluid bolus 20 ml/kg (.9 NaCl or LR) PLUS Vasopressors if MAP is judged to be critically low SBP < 90 mmHg, or MAP < 65 mmHg, or Lactate > 4 mmol/L CVP < 8 mmHg Insert CVP Catheter Boluses crystalloid or colloid equivalent until CVP > 8 mmHg Check MAP Assess ScvO2 Achieve ALL Goals? < 70% Dobutamine or RBCs depending on HCT MAP ≥ 65 Resuscitation complete. Establish re-evaluation intervals. YES
  38. 58. Benefits of EGDT <ul><li>$12,000.00 reduction in total hospital charges </li></ul><ul><li>34% reduction in sepsis mortality </li></ul><ul><li>3.8 reduction in hospital days </li></ul>
  39. 59. References <ul><li>Chest 2005;128:554s-560s </li></ul><ul><li>Chest 2006; 130: 1579-1595 </li></ul><ul><li>Intensive Care Medicine 2004; 30:2170-2179 </li></ul><ul><li>Crit Care Med 2003; 31:S658-S667 </li></ul><ul><li>Current Opinion Critical Care 2001; 7: 204-211 </li></ul><ul><li>NEJM 2001; 345: 1368-1377 </li></ul><ul><li>Critical Care Medicine 2002; 30: 1686-1692 </li></ul><ul><li>Circulation 1969; 40: 165 </li></ul><ul><li>Thorax 2002; 57: 170-177 </li></ul><ul><li>Academic Emer Med 1999; 6: 421 </li></ul>

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