venous blood gas reference intervals

Venous Blood Gas

Reference IntervalsThe NSW Health Pathology approach

Andrea Rita Horvath

Department of Clinical Chemistry & Endocrinology

NSW Health Pathology, Prince of Wales Hospital, Sydney

[email protected]

mailto:[email protected]

Outline

Background

Methods

Results

Transferability of the VBG RIs

Conclusions

Kirsty Ress NSW Health Pathology

Gus Koerbin NSW Health Pathology

Doug Chesher NSW Health Pathology

Samarina Musaad NZPOCTQAG / ARQAG

Ken Sikaris Melbourne Pathology

David Hughes ACT Pathology

Robert Flatman Sullivan Nicolaides Pathology

Goce Dimeski QLD Pathology

Frank Alvaro NSW Health Pathology

Joshua Ryan NSW Health Pathology

Anthony Diamond NSW Health Pathology

Dorra Arvanitis NSW Health Pathology

Andrew Sargeant NSW Health Pathology

NSWHP Clinical Chemistry Stream and POCT Advisory Group

Acknowledgements

Background

NSW Health Pathology Blood Gas Service338 devices

105 ABL 800 series, 16 ABL 90 flex

15 GEM 4000

202 i-STAT

Outline

Background

Methods

Results


Conclusions

Methods

Systematic review of the literature

RI study

Survey of laboratory RIs

Consensus of chemical pathologists

Clinical consultation and consensus

Verification and transferability testing

using flag rates and 95 percentile ED

population data

Outline

Background

Methods

Results


Conclusions

Systematic literature review1996-2016: No VBG RI studies in humans

Systematic literature review

Human studies were only on ABG-VBG differences mostly in

sick patients

Review No. of studies

and disease

states*

Difference (VBG – ABG)

pH HCO3

(mmol/L)

pCO2

(mmHg)

pO2

(mmHg)

Lactate

(mmol/L)

Ress (2016)* 47 (All) -0.032 1.0 5.3 -56.0 0.13

Bloom et al (2014) 3-15 (All) -0.033 1.0 4.4 - 0.25

Bryne et al (2014) 18 (All) -0.030 - 3.9 -36.8 -

Kelly (2013) 13 (ED) -0.034 1.2 6.2 - -

Kelly et al (2010) 3-10 (ED) -0.035 1.4 5.7 - -

Lim et al (2010) 6 (COPD) -0.028 1.3 5.9 -18.7 -

Kelly et al (2006) 3 (DKA) -0.020 - - - -

* Median of all studies

ED – Emergency Department, COPD - Chronic Obstructive Pulmonary Disease, DKA – Diabetic Ketoacidosis

All – No specific disease state included in the study. All disease states were included (e.g. COPD, DKA, healthy, critically ill and

emergency department patients).

NSW VBG RI study

Analyte Median

Average

Deviation

Percentile

(Non-coning)

Tukey

(Non-Para)

Dixon-Reed

(Non-Para)

pH 7.31 – 7.43 7.29 – 7.41 7.29 – 7.41 7.29 – 7.41

pO2 (mmHg) 14 - 54 15 - 64 15 - 49 15 - 64

pCO2 (mmHg) 39 - 61 38 - 61 38 - 60 38 – 61

Bicarbonate (mmol/L) 23.0 – 31.8 23.4 – 30.8 23.4 – 30.7 23.4 – 30.8

Lactate (mmol/L) 0.5 – 2.3 0.5 – 3.1 0.5 – 2.0 0.5 – 3.1

Sodium (mmol/L) 134 - 146 136 - 146 136 - 146 136 – 146

Potassium (mmol/L) 3.6 – 4.7 3.7 – 4.7 3.7 – 4.7 3.7 – 4.7

Chloride (mmol/L) 100 - 112 101 - 110 101 - 109 101 – 110

Ionised Ca (mmol/L) 1.17 – 1.29 1.16 – 1.32 1.16 – 1.29 1.16 – 1.32

n=216 healthy adult volunteers; 2/3 female, 1/3 male; age: 18-70y (80% 26-56y)Radiometer ABL 800 series blood gas analyser in one laboratory location

Safe-PICO syringes for sampling

Review by chemical pathologists

Review by

clinicians

Final

clinical &

laboratory

consensus

Evolution of the NSWHP VBG RI

Analyte RI modelled on

ABG-VBG

differences

NSW RI study NSWHP clin.

chem. stream

consensus

NSWH clinical

and laboratory

consensus

pH 7.32 – 7.42 7.29 – 7.41 7.30 – 7.40 7.30 – 7.40

pO2 (mmHg) 19 – 49 15 – 64 No RI No RI

pCO2 (mmHg) 40 - 50 38 – 61 40 – 60 40 – 50

Bicarbonate (mmol/L) 23 – 29 23 – 31 22 – 32 22 – 32

Lactate (mmol/L) <2.2 0.5 – 3.1 0.5 – 2.5 <2.0

Ionised Ca (mmol/L) NA 1.16 – 1.32 1.15 – 1.30 1.15 – 1.30

Sodium (mmol/L) NA 136 - 146 136 - 146 136 - 146

Potassium (mmol/L) NA 3.7 – 4.7 3.7 – 4.7 3.7 – 4.7

Chloride (mmol/L) NA 101 – 110 101 – 110 101 – 110

“From a consequentialist

standpoint, a morally right act

(or omission from acting) is one

that will produce a good

outcome, or consequence.”

Demosthenes

https://en.wikipedia.org

“Every advantage in the

past is judged in the light

of the final issue”

Outline

Background

Methods

Results


Conclusions

Transferability: 95% and flag ratesLocation

‒ NSW (public)

‒ ACT (public)

‒ VIC (private)

‒ QLD (public & private)

‒ NZ

Instruments

‒ 65% Radiometer ABL 90 and 800 series

‒ 28% IL/Werfen GEM

‒ 5% Abbott i-STAT

‒ 2% Siemens Rapidpoint 500

N=92,728 adult (>18 yr) inpatient episodes with VBG results

‒ 89% ED (n=82,786)

‒ 8% ED, ICU, CCU mixed population (n=7,814)

‒ 3% non-ED, non-ICU wards (n=2,128)

Limitations of data/data analysis‒ All (not just single) episodes

‒ No age and gender breakdown (but majority is elderly); no exclusion of outliers

‒ Suitable for instrument comparison but not for RI verification

NSW58%

ACT25%

VIC7%

QLD5%

NZ5%

VBG 95% of ED population - pH

7.00

7.10

7.20

7.30

7.40

7.50

7.60

7.70

1 2 3 4 5 6 7 8 9 10 11

Laboratory

pH

7.21-7.497.19-7.50 7.20-7.54 7.22-7.52

ABL 800 series Radiometer GEM ILi-

STA

T A

bb

ott

Rap

idp

oin

tS

iem

en

s

LRL Flagging Rate - pH

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

pH Lower Reference Limit:

NSWHP – 7.3, NSW RI Study – 7.29

Laboratory

% o

fpH

Results F

lagge

d

ABL 800 series Radiometer

i-S

TA

T A

bb

ott

Rap

idp

oin

tS

iem

en

s

GEM ILE

D

ED

&IC

U

No

n-E

D&

ICU

No

n-E

D

URL Flagging Rate - pH


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

GEM IL

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

pH Upper Reference Limits:

NSWHP – 7.4, NSW RI Study – 7.41

Laboratory

% o

f pH

Results F

lagge

d

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10 11

Laboratory

pC

O2

(mm

Hg

)VBG 95% of ED population – pCO2

ABL 800 series Radiometer GEM ILi-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

27 – 68 24 – 67 28 – 66 30 – 66

LRL Flagging Rate – pCO2

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f pC

O2

Results F

lagge

d

pCO2 Lower Reference Limit:

NSWHP – 40 mmHg, NSW RI Study – 38 mmHg


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

GEM IL

URL Flagging Rate – pCO2

pCO2 Upper Reference Limit:

NSWHP – 50 mmHg, NSW RI Study – 61 mmHg

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f pC

O2

Results F

lagge

d

ABL 800 series Radiometer GEM IL

i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

VBG 95% of ED population – Bicarbonate

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Bic

arb

onate

(mm

ol/L)

ABL 800 series Radiometer GEM ILi-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

15 – 3415 – 33 17 – 35 17 – 33

LRL Flagging Rate – Bicarbonate

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f B

icarb

onate

Results F

lagge

d

Bicarbonate Lower Reference Limit:

NSWHP – 22 mmol/L, NSW RI Study – 23 mmol/L


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

URL Flagging Rate – BicarbonateBicarbonate Upper Reference Limit:

NSWHP – 32 mmol/L, NSW RI Study – 31 mmol/L

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f B

ica

rbo

na

te R

esu

lts

Fla

gge

d

ABL 800 series RadiometerGEM IL

i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Lacta

te(m

mol/L)

VBG 95% of ED population – Lactate


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

0.6-6.50.6-6.1 0.9-5.4 0.7-4.6

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f Lacta

te R

esults F

lagge

dURL Flagging Rate – Lactate


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

Lactate Upper Reference Limit:

NSWHP – <2 mmol/L, NSW RI Study – 3.1 mmol/L

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Ionis

ed C

a(m

mol/L)

VBG 95% of ED population - iCa


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

0.98-1.341.00-1.31 1.01-1.31 0.98-1.29

LRL Flagging Rate – iCaiCa Lower Reference Limit:

NSWHP – 1.15 mmol/L, NSW RI Study – 1.16 mmol/L

0

10

20

30

40

50

60

70

80

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f Io

nis

ed C

a R

esults

Fla

gge

d


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

URL Flagging Rate – iCaiCa Upper Reference Limit:

NSWHP – 1.30 mmol/L, NSW RI Study – 1.32 mmol/L

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12

NSWHP FR

Study FR

Laboratory

% o

f Io

nis

ed C

a

Results F

lagge

d


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

me

ns

110

120

130

140

150

160

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Sodiu

mVBG 95% of ED population - Na


i-S

TA

T A

bb

ott

Ra

pid

po

int

Sie

men

s

NSWHP RI: 136-146 mmol/L;

HRI (serum/plasma): 135-145 mmol/L

126-145127-146 126-146 126-142

Ra

pid

po

int

Sie

men

sABL 800 series Radiometer

i-S

TA

T A

bb

ott

GEM IL

VBG 95% of ED population - K

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Pota

ssiu

m(m

mol/L)

NSWHP RI: 3.7-4.7 mmol/L

HRI (serum/plasma): 3.5-5.2 mmol/L; 3.2-4.9 mmol/L (paed. plasma)

3.0-6.33.0-5.9 3.1-5.82.9-6.0

Ra

pid

po

int

Sie

men

sABL 800 series Radiometer

i-S

TA

T A

bb

ott

GEM IL

VBG 95% of ED population - Cl

70

80

90

100

110

120

130

1 2 3 4 5 6 7 8 9 10 11

Laboratory

Chlo

ride

(mm

ol/L)

NSWHP RI: 101-110 mmol/L;

HRI (serum/plasma): 95-110 mmol/L

88-11293-114 90-115 92-112

Outline

Background

Methods

Results


Conclusions

Conclusions

Analyte NSW RI

study

NSWH clinical

and laboratory

consensus

Comments

Harmonisation Meeting

2018

Recommendations

pH 7.29 – 7.41 7.30 – 7.40 High URL flag rate – may

need fine tuningaccepted

pO2 (mmHg) 15 – 64 No RI Recommend ABG accepted

pCO2 (mmHg) 38 – 61 40 – 50 ‘URL’ = decision limit to

detect COPD. It will flag 20-

25% healthy; clinical F/U

accepted, with some arguing

that this is a decision limit and

we should still cite a RI that has

a higher URL of ~60 mmHg

Bicarbonate (mmol/L) 23 – 31 22 – 32 HRI for serum/plasma accepted

Lactate (mmol/L) 0.5 – 3.1 <2.0 Same as ABG RI accepted

Ionised Ca (mmol/L) 1.16 – 1.32 1.15 – 1.30 Investigate high flag rate at

LRL

Suggested to investigate further

and look into sampling issues

that may explain the high flag

rate at the LRL

Sodium (mmol/L) 136 - 146 136 - 146 Notable instrument

differences

?HRI for plasma: 135-145

To be discussed further in the

blood gas working party

Potassium (mmol/L) 3.7 – 4.7 3.7 – 4.7 ?HRI for plasma: 3.2-4.9

(paed) or 3.5-5.2 (adults)



Chloride (mmol/L) 101 – 110 101 – 110 Notable instrument

differences

?HRI for plasma: 95-110



The below VBG Reference Intervals are adaptable to all major platforms (ABL, i-STAT,

GEM, Rapidpoint) after local verification. Electrolytes need further investigation.

7.30-7.40

40-50

15-64*

22-32

136-146

3.7-4.7

101-110

<2.0

* NSWHP RI study – NB; pO2 RI is not recommended in VBG

Proposed

NSWHP RI

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exacerbations of chronic obstructive pulmonary disease in the emergency department. European

Journal of Emergency Medicine. 2010;17(5):246-8

Kelly AM. Agreement between arterial and venous blood gases in emergency medical care: a

systematic review. Hong Kong Journal of Emergency Medicine. 2013;20(3):166.

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department: a systematic review and meta-analysis. European Journal of Emergency Medicine.

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Byrne AL, Bennett M, Chatterji R, Symons R, Pace NL, Thomas PS. Peripheral venous and arterial

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2014;19(2):168-75 81-8

How to Read a Venous Blood Gas (VBG) - Top 5 Tips - https://acadoodle.com/articles/how-to-read-a-

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