Blood Gas Reference Intervals

Home , Reference range

The Struggle Continues

Roger Ashton Pathlab Whakatane Walking on eggshells

Riding on the shoulders of those who have tried before

Lynne Clarke – Waikato Tony Mace - Pathlab

And many others including : RCPA ARQAG AACB

Blood Gas Reference Intervals

Lyn Clarke Dip MLT, BBS June2016 Analysers in New Zealand

 Radiometer – majority of large volume sites  41 ABL800  11 ABL80  25 ABL90  iSTAT – Large numbers in low volume sites  Siemens – A few sites APPROX 9  GEM At least 2  ? Others e.g. Epoch, Roche, Novastat 12 New Zealand Locations Reality

 Few Laboratories have references in their methods. • Some use vendor ranges.

 There is a lot of data on cord bloods

 Plenty of data on animals

 Very little data on adults

 Text books often have no references or reference each other e.g Tietz, Sigaard-Andersen, Wallach, New England Medical Journal

 Still cannot get agreement on UNITS

Klaestrup et al 2011

 182 patients  Medical Students and health professionals

 118 medical students practising on each other  76% <40 yrs (138)  Age range 20-76 yrs  Radiometer analyser

Conclusions 2015

 CLSI now allows for Consensus Ranges

 Logically the ranges should be the same throughout the country.

 Get buy in from Pathologists

 Set up a meeting of the participants

iSTAT Comparison of Reference Intervals

REFERENCE RANGES LITERATURE Tietz 4th ed ABBOTT Klaestrup et Widdop Cousineau et al Test Age Range 2006 ISTAT Radiometer al (2011) (2002) ( 2006) Helwig (1996) Yeomans (1985) Victory (2004) Shirley (1996) Number in study ? ? ? 182 126 16060 146 20456 53 pH Arterial 1 Day 7.29-7.45 7.35 - 7.45 7.35-7.45 Male 7.376 -7.455

Female 7.35-7.45 7.384-7.468 Female/Male 7.35 - 7.45 7.382 - 7.462 pH Venous Adult 7.32-7.43 7.31 - 7.41 60-90 7.31-7.42 pH - Capillary 36-60 hours 7.312-7.473 pH Cord Blood- Arterial 7.28±0.05 7.10-7.38 7.15-7.43 7.17-7.31 pH Cord Blood - Venous 7.35±0.05 7.20-7.46 7.24-7.49 7.27-7.45 54-95 mmHg pO2 Arterial 1 Day 7.18-12.64 kPa

83-108 mmHg 83-108 mmHg >1 Day 11.04-14.36 kPa 11.07-14.4 kPa 11.1-15.5 kPa pO2 Venous pO2 Capillary 36-60 hours 32.8- 61.2 mmHg 80 -105 mmHg pO2 Cord Blood- Arterial 6.7 -14 kPa 6-30 mmHg 3.8-33.8 mmHg pO2 Cord Blood - Venous 16-43 mmHg 15.4-48.2 mmHg 27-40 mmHg pCO2 Arterial Newborn 3.59-5.32 kPa 35-48 35-48 mmHg 35-45 mmHg mmHG(M/F) Adult Male 4.66-6.38 kPa 4.67 - 6.0 kPa 4.67-6.40 kPa 4.5-6.0 kPa 32-45 mmHg 35-45 mmHg Adult Female 4.26 - 5.99 kPa 4.67 - 6.0 kPa 4.1 - 5.6 kPa Female/Male 4.3-6.0 kPa 0.8-0.83 kPa Higher than 41-51 mmHg pCO2 Venous arterial 5.47 - 6.8 kPa Where we are currently

 pH

 Tietz (2006) 7.35 – 7.45  Wallach (1996) 7.36 – 7.44  Radiometer, Siemens iSTAT 7.35 – 7.45  Klaestrup et al (2011) 7.382 – 7.462

 Propose 7.35 - 7.45 pO2

Adult

KPA mmHg Semantics and conversion factors 1 7.5 2 15 3.5 26.25 mmHg 4 30 6 45 160 6.7 50.25 KPA mmHg 140 7 52.5 1 7.5 7.6 57 2 15 120 8 60 4 30 9.34 70.05 6 45 100 9.5 71.25 8 60 80 10 75 10 75 10.65 79.875 12 90 60 10.66 79.95 14 105 40 10.67 80.025 16 120 11.34 85.05 20 18 135 11.4 85.5 20 150 0 12 90 0 5 10 15 20 25 13.3 99.75 14 105 16 120 18 135 • Do we want our Reference Range to be exact? 20 150 • To how many decimals? • Or Memorable? • Or close enough? • Or Clinically Significant NUMERICAL CREEP 11 KPa = 82.5 mmHg “ Let’s call it 83” 83 mmHg = 11.1 KPa “must be exact”

80 ~ 10.7 85 ~ 11.4

100 ~ 13.3 108 ~ 14.4 PO2 Adult

 Low 70 – 85 mmHg = 9.3 – 11.4 KPa

 High 100 - 108 mmHg = 13.3 - 14.4 Kpa

 9.3 - 14.4 Kpa ?? Too wide, and not referenced ??  ORIGINAL PROPOSAL  Tietz 83 - 108 mmHg = 11.0 to 14.4 KPa

P O 2

 ARQAG Proposal

 75 - 105 mmHg 10 - 14 KPa PCO2

Wider variation depending on source Tried looking at Low & High separately Some sources had different Male and Female

Test Age Range ADHB Christchurch Waikato Wellington WDHB Hawkes Bay Whakatane pCO2 Arterial 4.6-6.0 kPa 24-30.0 mmHg 4.5-6.0 kPa 35-45 mmHg 4.6 -6.0 KPA 35-45 4.67 - 6.00 kPa pCO2 Venous 5.0-6.4 kPa 25-33.0 mmhg 5.0-6.4 kpa 38-48 mmHg 41-51 5.47 - 6.8 kPa

PCO2 Adult  Low MALE 32 – 37 mmHg = 4.3 – 4.9 KPa  Low FEMALE 27 – 32 = 3.6 – 4.3 Kpa  LOW limit NZ LABS 24 – 30 = 3.4 – 4.0 Kpa

 High MALE 45 – 48 = 6.0 – 6.66  High FEMALE 43 – 45 = 5.6 – 6.0  High limit NZ LABS 30 – 48 = 4.0 – 6.67 Kpa

 DO WE NEED GENDER SPECIFIC RANGES ??

PCO2 Adult

 Tietz  Male 35 – 48 mmHg = 4.7 – 6.4 KPa  Female 32 – 45 mmHg = 4.3 – 6.0 KPa

 ARQAG PROPOSAL  35 - 45 mmHg 4.7 - 6.0 KPa

Consensus Recommendation NZPOCTQAG / ARQAG NSW Pathology • source  pH 7.35 - 7.45 Tietz

 PO2 75 - 105 mmHg = 10.0 to 14.0 Kpa Tietz / ARQAG

 PCO2 35 – 45 mmHg = 4.7 to 6.0 KPa Tietz / ARQAG  HCO3 22 to 28 mmol/L  Base Excess -3 to +3 mmol/L  Lactate less than 2.0 mmol/L

Cord Bloods Agreed 2018 What is next?

 HAEMOGLOBIN  HaemQAG RCPA

 Haematology nationwide recommendations 2014  Needed “pruning” to give 10 age related for use in POC Number of significant figures

 The reference intervals are rounded regardless of the number of decimals in the original source.  pH: Rounded to 2 decimal places.  pCO2: Rounded to 0 decimal place for mmHg and 1 decimal place for kPa.  pO2: Rounded to 0 decimal place for mmHg and 1 decimal place for kPa.  ctHb: Rounded to 0 decimal place. (1 decimal for g/dl )  sO2: Rounded to 0 decimal place for % and 2 decimal places for fraction. Laboratories may choose to report to a higher number of Decimals, but Ranges should be rounded  Other parameters  (Electrolytes, Metabolites, & Co-oximetry)  Generally follow ARQAG

 Do we need separate ranges?  Serum, Plasma, Whole Blood?

 Potassium Venous Ranges

 To be discussed in more detail by Rita  Currently before ARQAG



Where to next?

 Propose pH , PCO2, PO2 ranges to

 NZPOCTQAG  ARQAG  PATHOLOGISTS  Other Quality Groups

 Suggest need for haste and assertiveness. onions References

 B.E. Statland, Clinical Decision Levels for Lab Tests (Oradell, NJ: Medical Economic Books, 1987).  P.C. Painter, J.Y. Cope, J.L. Smith, “Reference Ranges, Table 41–20” in Tietz Textbook of Clinical Chemistry—Second Edition, C.A. Burtis and E.R. Ashwood, eds. (Philadelphia: W.B. Saunders Company, 1994).  CLSI Defining, Establishing and Verifying Reference Intervals in the Clinical Laboratory – Third Edition v28 n30 Base Excess??

 Standard Base Excess ?? SBE  Actual Base Excess ?? ABE

 Bicarbonate  HCO3  Plasma  Standardized  K 3.5-5.2 mmol/L  Na 135-145 mmol/L  Cl 95-110 mmol/L  pH 7.30-7.40  PO2 No RR  PCO2 5.0-6.4 Kpa 40-50 mmHg  HCO3 22-28 mmol/L  Lactate < 2.0 mmol/L  Ionized Ca 1.15-1.30 mmol/L