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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

2013, Wynyard Hall

Luciano Gattinoni, MD, FRCP

Università di Milano

Fondazione IRCCS Ca’ Granda

Ospedale Maggiore Policlinico

Milan, Italy




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


Hydrogen

Oxygen


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

-

-

-

-

-

-

-

-

-

-

-


Lactic acid

Lactate

C3 H6 O3

CH3CH(OH)COO−


Pr

-

Pr

Pr

H

+H+

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


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


Types of active transport

http://www.emc.maricopa.edu/faculty/farabee/biobk/biobooktransp.html


H+ number

1

Na+ number

1000000

:

H+ volume

1

:

Na+ volume

120


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


The Stewart’s approach

The independent variables are:

The in

Strong Ion difference

PCO2

Amount of weak acid

(Proteins, Phosphate, Hemoglobin)


[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


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


Whatdoes Nature do torestore the pH?


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


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


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


7.55 different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05.

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.


Effects of infusion SID different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05.

(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.


PCO different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. 2 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+]


PCO different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. 2, pH and water


PCO different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. 2,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+]


PCO different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. 2 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


Effects of infinite dilution in open system (constant PCO different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. 2)

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


Effects of infusi different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. on 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.


Effects of infusi different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. on 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.


Effects of infusi different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. on

(12 pigs)

Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]


Effects of infusi different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. on

(12 pigs)

Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]


Effects of infusi different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. on

(12 pigs)

Langer T. et al. Intensive Care Med. 2012 Jan 25. [Epub ahead of print]


Different different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. typesofcrystalloidsinfused

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


Variation different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. of 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


Variation different measuring points. Saline group = white dots; Ringer's group = black dots. Star = intragroup differences, P < 0.05; triangle = intergroup differences, P < 0.05. of 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


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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