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Acid-Base balance revisited

Acid-Base balance revisited. 2013, Wynyard Hall. Luciano Gattinoni, MD, FRCP Università di Milano Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milan, Italy. Sodium. Chlorine. Ionic Bond. Sodium Atom 11 p+ 11 e- Net charge = 0. Sodium Ion 11 p+ 10 e-

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Acid-Base balance revisited

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  1. Acid-Base balance revisited 2013, Wynyard Hall Luciano Gattinoni, MD, FRCP Università di Milano Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milan, Italy

  2. Sodium

  3. Chlorine

  4. Ionic Bond Sodium Atom 11 p+ 11 e- Net charge = 0 Sodium Ion 11 p+ 10 e- Net charge = +1 Chlorine Atom 17 p+ 17 e- Net charge = 0 Chloride Ion 17 p+ 18 e- Net charge = -1

  5. Hydrogen Oxygen

  6. Na+ and Cl- ions become surrounded by spheres of H2O molecules Cl- Na+ Na+ Cl- + + + + + + + + + + + H H H H H H H H H H H H H H H H H H H H H H O O O O O O O O O O O - - - - - - - - - - -

  7. Lactic acid Lactate C3 H6 O3 CH3CH(OH)COO−

  8. Pr - Pr Pr H +H+ 1 gr. of PROTEINS may bound 0.11 mEq [H+]

  9. H O O- O- O H C C C O O -O + O C H+ + 2H+ + H H H O O O O CO2 Carbon Dioxide H2CO3 Carbonic Acid HCO3- Bicarbonate CO32- Carbonate CO2 + H2O ßà HCO3- + H+      pKa = 6.10 HCO3-ßà CO3--+ H+       pKa = 8.92

  10. Types of active transport http://www.emc.maricopa.edu/faculty/farabee/biobk/biobooktransp.html

  11. H+ number 1 Na+ number 1000000 : H+ volume 1 : Na+ volume 120

  12. The players Water 55000 mmol/L Strong Ion+ 150 mmol/L Strong Ion- 110 mmol/L Weak acid- 40 mmol/L H+ 0.0000004 mmol/L

  13. The Stewart’s approach The independent variables are: The in Strong Ion difference PCO2 Amount of weak acid (Proteins, Phosphate, Hemoglobin)

  14. [Na+] 142 + - [K+] 4.1 [Ca2+] 4.6 [Mg2+] 1.6 [HCO3-] 24.5 [Alb-] 12.28 [Pi-] 1.82 [XA-] 8 [Cl-] 106 Plasma electroneutrality 150 BB= [HCO3-] +[A-] i.e. the negative charge mEq/L 100 SID=[Na+]+[K+]+[Ca2+]+ [Mg2+]-[Cl-]-[XA-] 50 i.e. BB=SID

  15. Metabolic acidosis: generation Na+ K+ mEq/L Ca++ OH- OH- Cl- 160 Lactate- A- HCO3- 3 OH- HCO3- 140 HCO3- 32 42 A- 120 A- 100 80 Positive charges Negative charges Negative charges

  16. Whatdoes Nature do torestore the pH?

  17. Metabolic acidosis Within the “BB” Na+ K+ mEq/L Ca++ OH- OH- Cl- 160 Lactate- A- HCO3- HCO3- 3 OH- HCO3- 140 32 32 A- A- 120 Hypocapnia 100 80 Positive charges Negative charges Negative charges

  18. Metabolic acidosis Within the “BB” Na+ K+ mEq/L Ca++ OH- OH- Cl- 160 Lactate- A- HCO3- 3 OH- HCO3- HCO3- 140 32 42 A- 120 A- 100 Chloride excretion 80 Positive charges Negative charges Negative charges

  19. Measured and calculated values (mean +/- SD) at the different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. Infused nearly 4.5-5 L Dilution nearly 30% Initial Vext nearly 15 L Scheingraber: Anesthesiology, 90(5).May 1999.1265-1270

  20. 7.55 pH dilution 20% dilution 30% 7.50 dilution 40% 7.45 7.40 7.35 7.30 7.25 baseline 0 10 20 30 40 50 SID (mEq/L) Effects of infusion SID Sterofundin Gelatin RL NS HES Carlesso E. et al. Intensive Care Med. 2011 Mar;37(3):461-8.

  21. Effects of infusion SID (in vitro experimental data PCO2 = 35 mmHg ) 18.3 ± 0.3 HCO3-Baseline Carlesso E. et al. Intensive Care Med. 2011 Mar;37(3):461-8.

  22. PCO2 and water Consider a volume of water equilibrated at different PCO2 values… [HCO3-]x[H+] = Kc [CO2 dissolved] H-H equation [HCO3-] pH = pK + log10 Electroneutrality [CO2 dissolved] [HCO3-]=[H+]

  23. PCO2, pH and water

  24. PCO2,water and SID Consider a volume of water equilibrated at different PCO2 values…with a strong ion difference higher than zero… [HCO3-]x[H+] = Kc [CO2 dissolved] H-H equation [HCO3-] pH = pK + log10 Electroneutrality [CO2 dissolved] [HCO3-]=[SID] + [H+]

  25. PCO2 and water SID 20 20 mEq/l 0.08 0.07 SID 15 15 mEq/l 0.06 0.05 SID [HCO3-] (mmol/l) 10 0.04 10 mEq/l 0.03 SID 5 0.02 5 mEq/l 0.01 SID 0.00 0 0 mEq/l 0 20 40 60 80 100 120 140 160 180 200 PCO (mmHg) 2

  26. Effects of infinite dilution in open system (constant PCO2) HCO3- mEq/L pH = pKc + log10 50 α PCO2 40 A- SIDD = HCO3-I 30 HCO3- SID 20 HCO3- SID 10 HCO3- SID 0 pH unmodified pH increase pH decrease SID A- prima

  27. Effects of infusion SID PCO2 = 40 mmHg pH 7.55 SIDdiluent = 50 7.50 SIDdiluent = 40 7.45 SIDdiluent = 30 SIDdiluent = 24.42 7.40 SIDdiluent = 20 7.35 SIDdiluent = 10 7.30 SIDdiluent = 0 7.25 baseline 20 30 40 Dilution (%) Carlesso E. et al. Intensive Care Med. 2011 Mar;37(3):461-8.

  28. Effects of infusion SID (in vitro experimental data) PCO2 = 35 mmHg SIDdiluent = 48 SIDdiluent = 36 SIDdiluent = 24 SIDdiluent = 18 SIDdiluent = 12 SIDdiluent = 0 Baseline Carlesso E. et al. Intensive Care Med. 2011 Mar;37(3):461-8.

  29. Effects of infusion (12 pigs) Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]

  30. Effects of infusion (12 pigs) Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]

  31. Effects of infusion (12 pigs) Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]

  32. Differenttypesofcrystalloidsinfused SID infused ~ 24 mEq/L [n = 13] (“balance” solution) SID infused ~ 30 mEq/L Study population [n = 20] (RIII + SF + RL) SID infused ~ 55 mEq/L [n = 24] (Rehydrating III – SID = 55) Courtesyof Dr. P. Caironi

  33. Variationof BE accordingto HCO3–baselinelevels HCO3– ≤ 23.5 mmol/L HCO3– > 23.5 mmol/L P < 0.01 Delta Base Excess [mmol/L] 8 6 P < 0.01 4 2 0 -2 SID ~ 24 SID ~ 30 SID ~ 55 N = 13 N = 20 N = 24 Courtesyof Dr. P. Caironi

  34. Variationof BE accordingtoinfused SID – baseline HCO3– 7 Delta Base Excess [mmol/L] 6 5 4 3 2 1 P = 0.017 0 < –1 – 1 - 12 12 - 19 > 19 Quartile distribution of SID infused – baseline HCO3– [mEq/L] Courtesyof Dr. P. Caironi

  35. Improvement have been made on safety through more balanced crystalloid solutions To maintain initial pH the infusion SID must be equal to HCO3- The clinical benefit of balanced crystalloid solutions has to be determined. Conclusions

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