Haukeland University Hospital, 17th January 2017

Hans-Peter Marti Renal Unit Haukeland University Hospital Bergen

Analyses of Acid-Base Disturbances

SomeslidesfromalectureofFredrikBorchsenius,UiO

Likevekten

•  Metabolismengirproduksjonavsyreikroppen•  pHmålikevelholdeskonstant

•  KroppenmåkviCesegmedsyre–  Lunger:CO2utskilles–  Nyrer:Ikke-flykMgesyrer(urinsyre,melkesyreetc)

H2O+CO2 HCO3 +H- +H2CO3

Lungemedisinsk avdeling

Hvordantablodgassprøve?

•  Vanligvisart.radialis

•  Vurderlokalanestesi

Lungemedisinsk avdeling

….…hypervenMlaMonwithrespiratoryalkalosis!

Allenstest •  Holdhåndenhøyt,knyChånden

•  Komprimerbåderadialisogulnaris

•  Senkhåndenogåpnehånden

•  Slippoppforulnaris•  Håndenskalfåfargeigjeninnen6sek

Lungemedisinsk avdeling

Feilkilder

Lungemedisinsk avdeling

•  Prøvemateriale–  Arterie,kapillærellervenøs

•  Luftisprøyten?–  Ikkeover5%volum?

•  Temperatur–  Leggespåis

pH 7,36-7,44 pCO2 4,5-6,1 kPa Base Excess (BE) -3 – 3 mmol/L HCO3

- 22-26 mmol/L pO2 11-13 kPa Hb 11,7 – 15,3 g/dL (K)

13,4 – 17,0 g/dL (M)

SO2 95-100% FCOHb <1,5 % for ikke-

røykere Na 137-145 mmol/L K 3,5-5 mmol/L Cl 98-109 mmol/L iCa (pH7,4 normert) 1,13-1,28 Glu 4,0-6,0 Lac 0,4-1,3 PO2/FO2-ratio > 40++ AG 5,0 – 20/21 mmol/L

Referanseverdi

ABG Acid-Base Eval Josuah Steinberg

Blood pH - Acid Base Disturbance Calculator By Remarkable Edge, Lda

Free Apps!

Version 1.4 Jan, 2015

pCO2: 1 kPa = 7.5 mmHg

PrinciplesofAcid-BaseDisorders

•  Acidemia:serumpH<7.36•  Alkalemia:serumpH>7.44

•  Acidosis:pathologicprocessthatlowers[HCO3

-]orraisesPaCO2•  Alkalosis:pathologicprocessthatraises[HCO3

-]orlowersPaCO2

8

Cl-

Algorithm for simple (not mixed) Acid-Base Disorders

BE↓ BE↑

BE↑ BE↓

Compensation adequate?

Cl- = N or ↑ ?

pCO2: 1 kPa = 7.5 mmHg; 1 mmHg = 0.13 kPa

How common is metabolic acidosis in patients with chronic kidney disease (CKD)?

Hyperchloremic (AG normal) vs. Normochloremic (AG ↑) Acidosis

Normal Normochloremic acidosis: Anion gap (AG) increased

Hyperchloremic acidosis: Anion gap (AG) normal

[Na+ + K+] - [Cl- + HCO3 -] = AG (12±4)

AG 25 Na+

140

HCO3 -

15

Cl-

105

AG 15 Na+

140 HCO3

-

25

Cl-

105

AG 15 Na+

140 HCO3 -

15 Cl-

115

(5-20 mmol/L)

Anion Gap (AG) and Albumin

A lower serum AG (all anions - all cations) can occur due to decreased concentration of anions, which is most often due to hypoalbuminemia.

The serum AG falls by about 2.5 mmol/L for every 10 g/L reduction in the serum albumin (normal: 39-48g/L) concentration.

Correct anion gap = Observed anion gap + 0.25 (normal albumin-observed albumin) for albumin measured in g/L

Urine anion gap <0

Urine anion gap ≥0

Urine anion gap ≥0

AG>20

Cl-↑ Cl- No

Renal Tubular Acidoses (RTA): Types I, II and IV

Type II

Type IV

Type I

Drug-induced: ACEI, ARB, spironolactone

Renal Tubular Acidosis (RTA): Hyperchloremic (AG normal)

K+

AGurine

Read also: Soleimani, AJKD 2016

Palmer BF, Clegg DJ. N Engl J Med 2015;373:548-559.

Phases of Metabolic Acidosis in Patients with Diabetes

Eksempel

Lungemedisinsk avdeling

? pH = 7,32

PCO2 = 8,5-

HCO3 = 35BE = 7,5PO2 = 8,8

Vurdereblodgasser

Lungemedisinsk avdeling

•  Spm1.Acidoseelleralkalose?•  Spm2.Erforstyrrelsenrespiratorisk,metabolskellerkombinert

–  PCO2omv.prop.medalveolærvenMlasjon–  HCO3ogBE–  Hva”passer”medaktuellepHverdi?

•  Hvismetabolskacidose–  Aniongap?

Vurdereblodgasser

Lungemedisinsk avdeling

pH PCO2 BE

Resp.acidose <7,35 >6

Resp.alkalose >7,45 <4,7

Met.acidose <7,35 <-2

Met.alkalose >7,45 >+2

Kompensering

•  Respiratorisk–  ½time–12Mmer–  PCO2økesmed0,09kPaforhver1meq/løketHCO3

•  Metabolsk–  3Mmer–3døgn–  HCO3økermed1meq/lforhver1,3øketPaCO2

Vurdereblodgasser

•  HvasåhvispHernøytralmensPCO2ogBEerpatologisk?– Fullkompensertacidose/alkalose?

Eksempel

pHPCO2

= 7,32= 8,5= 35HCO3

-

Acidose

BE = 7,5

PO2 = 8,8

Eksempel

pH = 7,32PCO2 = 8,5HCO3

- = 35BE = 7,5PO2 = 8,8

Acidose

Alkalose

Konklusjon:Respiratoriskacidose,delviskompensert

Eksempel

pHPCO2

= 7,52= 4,0= 20HCO3

-

Alkalose

BE = -4,5PO2 = 12,8

Eksempel

pH = 7,52PCO2 = 4,0HCO3

- = 20BE = -4,5PO2 = 12,8

Alkalose

Acidose

Konklusjon:Respiratoriskalkalose,delviskompensert

”Aniongap”ernormalt<20

Anion Kation Diff

Na+ 140

K+ 4 Cl- 104 HCO3- 24 Sum 128 144 16

Dessuten Protein Org. syrer

Fosfater, sulfater

Ca K

Mg

Metabolskacidose

Anion gap > 20 –  Uremi–  Ketoacidose–  Intox

§  Metanol§  Etylenglykol§  Salicyl

–  Melkesyre§  Sepsis,hjertesvikt

Anion gap < 20 –  HCO3 tap(diare)–  Medikamenter(Diamox)–  Hyperalimentering–  Renaltubulæracidose

-

Anion gap = Na+ + K+ - (Cl- + HCO3 ) -

Metabolskalkalose

•  TapavHCl– Dehydrering(oppkastea)

•  Diuretika•  Hypokalemi,hyperkalsemi(milk-alkalisyndrom)•  Alkaliinntak(bikarbonat)•  Hypovolemi

pH 7,36-7,44

pCO2 4,5-6,1kPa

BaseExcess(BE) -3–3mmol/L

HCO3- 22-26mmol/L

pO2 11-13kPa

Hb 11,7–15,3g/dL(K)13,4–17,0g/dL(M)

SO2 95-100%

FCOHb <1,5%forikke-røykere

Na 137-145mmol/L

K 3,5-5mmol/L

Cl 98-109mmol/L

iCa(pH7,4normert) 1,13-1,28

Glu 4,0-6,0

Lac 0,4-1,3

PO2/FO2-raMo >40++

AG 5,0–20/21mmol/L

Referanseverdi

pH PCO2 BEResp.acidose <7,35 >6Resp.alkalose >7,45 <4,7Met.acidose <7,35 <-2Met.alkalose >7,45 >+2

Compensation adequate?

pCO2: 1 kPa = 7.5 mmHg

pCO2 = 7.23 kPa = 54 mmHg (34-46) = approx. +14mmHg↑

HCO3- = 31 mmHg (22-26) = approx. +7mmHg↑ = adequate for chronic respiratory acidosis

Summary: Acid-Base Disturbances

pH = pK‘ + log [HCO3

-]

0.03 PaCO2