BLOOD GAS (ARTERIAL AND VENOUS

BLOOD GAS (ARTERIAL AND VENOUS Gus Koerbin Adjunct Professor, University Of Canberra, Faculty of Health Visiting Fellow, ANU, College of Health and Medicine

WHAT ARE WE GOING TO DISCUSS? Gus Koerbin Introduction and some recapping of 2017 Roger Ashton ABG The New Zealand data Gus Koerbin Australian ABG flagging rates Rita Horvath VBG The NSW Health experience Gus Koerbin Some additional venous data Summary

Some introductory questions

Some introductory questions Question 1 Who has VBG reference intervals? Question 2 Who has different ABG and VBG reference intervals? Question 3 Is it appropriate to report Arterial intervals for venous gases?

What are we going to work through today? Is there enough data to decide whether to harmonise RI? What are the flagging rates? Are the RI that will be discussed suitable? We will not discuss all the analytes that are produced when a blood gas is requested but concentrate on a few such as: ph, pco2 po2 bicarb, ica,

Is there any instrument related reason not to harmonise a group of analytes? Ideally we would use a bias study using commutable material (Human) Is this feasible? Is it possible? RCPA QAP Not human material But does give us an idea of how instruments perform relative to each other Consider ph, pco2, po2 and ica

Recap of 2017 RCPA QAP Survey of labs and industry arterial RI s

ph ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT SEALS Radiometer SEALS ISTAT SSWPS Radiometer, Siemens istat ph 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.34-7.44 7.35-7.45 7.35-7.43 7.35-7.45 7.36-7.44

pco2 ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL PCO 2 [mmhg] 35-45 35-48 (M) 32-45 (F) SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT SEALS SEALS ISTAT Radiometer SSWPS Radiometer, Siemens istat 35-45 35-45 35-45 32-48 35-45 35-45 35-45 32-45 35-45 35-45

po2 ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT SEALS SEALS ISTAT Radiometer SSWPS Radiometer, Siemens istat PO 2 [mmhg] 83-108 83-108 80-105 75-100 80-100 83-108 75-100 75-100 75-100 69-116 80-105 80-100

ica ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT SEALS Radiometer SEALS ISTAT SSWPS Radiometer, Siemens istat ica ++ [mmol/l] 1.15-1.30 1.15-1.29 1.12-1.32 1.15-1.32 1.1-1.4 1.15-1.32 1.12-1.30 1.04-1.24 1.15-1.30 1.1-1.3 1.12-1.32 1.15-1.29

Arterial Blood Gas We have seen some of the NSW data last year and it was based on survey results. Note: This has been updated in 2018 after consultation NSW Reference intervals by consensus ABG state of the art, flag rates 10-20% (later) Ken Sikaris has produced some Melbourne 2011-2017 flag rates differences

Venous Blood Gas In NSW in some instances there were no VBG RI s caused incidents in NSW Is it better to have something that is OK than nothing at all ISO requirements: must have some way of interpreting (not necessarily RI) but you must have soothing to support the interpretation. Some more VBG flagging rates

Over to Roger

Arterial blood gas (Flagging rates) Gus Koerbin Adjunct Professor, University Of Canberra, Faculty of Health Visiting Fellow, ANU, College of Health and Medicine

Flagging rates Excess flagging of results can lead to inappropriate testing due to decreased specificity of the RI. The flagging rates provided in this review are those when community samples are considered.

NSW Health Agreed ABG Reference Interval Arterial (>19 years) RI Source ph 7.35-7.45 Consensus decision (Clinical Streams members) PO2 [mmhg] 75-105 Consensus decision (Clinical Streams members) PCO2 [mmhg] 35-45 Consensus decision (Clinical Streams members) HCO3- [mmol/l] 22-28 Consensus decision (Clinical Streams members) APUTS, QLD RI Arterial (>19 years) RI AACB/RCPA Source Electrolytes: Sodium [mmol/l] 136-146 135-145 Consensus decision (Clinical Streams members) APUTS Potassium [mmol/l] 3.7-4.7 3.5-5.2 Consensus decision (Clinical Streams members) APUTS Chloride [mmol/l] 101-110 95-110 Consensus decision (Clinical Streams members) APUTS Ionised Ca++ [mmol/l] 1.15-1.30 Consensus decision (Clinical Streams members)

BGAS Database (Melbourne ) 2001-2017 Art Ven Ven% Total DanEmerg 1,888 262 12.2% 2,150 DanICUf 32,054 1,045 3.3% 32,054 DanICUm 37,659 947 2.5% 37,659 EpwEmerg 871 8 0.9% 871 EpwICU 29,519 0 0.0% 29,519 FreeCCU 57,593 3,215 5.6% 57,593 FreeICU 43,514 109 0.3% 43,514 OutPat 5,317 39 0.7% 5,317 Ward 27,435 81 0.3% 27,435 All 235,850 5,706 2.4% 236,112 Courtesy K.Sikaris

Location (Sick) Melbourne : 2001-17 Courtesy K.Sikaris

Median Age = 71 y/o (Old) Courtesy K.Sikaris

Art ph Distributions Outpatients have much tighter ph distribution. Less acidosis than hospital patients Courtesy K.Sikaris

Art ph Cumulative (Flag Rate) 7.35-7.45 gives 10% flag rate in OP, but 30% flag rate for acidosis in inpatients Alkalosis flag rate is the same in IP and OP around 10% (NZ,NSW ABG RI red dashed lines) ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT Courtesy K.Sikaris SEALS Radiometer SEALS ISTAT SSWPS Radiometer, Siemens istat ph 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.35-7.45 7.34-7.44 7.35-7.45 7.35-7.43 7.35-7.45 7.36-7.44

Art pco2 Distributions pco2 distributions similar in IP and OP Courtesy K.Sikaris

Art pco2 Cumulative (Flag Rate) pco2 flag rate is much higher using 35-45 mmhg 15% for resp alkalosis and 25% for resp acidosis (NZ,NSW ABG RI red dashed lines) ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL PCO 2 [mmhg] 35-45 35-48 (M) 32-45 (F) SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT Courtesy K.Sikaris SEALS SEALS ISTAT Radiometer SSWPS Radiometer, Siemens istat 35-45 35-45 35-45 32-48 35-45 35-45 35-45 32-45 35-45 35-45

Art po2 Distributions po2 distribution shows biphasic distribution with probable contamination from venous samples Very few samples lie between 80-100 mmhg in IP or OP Courtesy K.Sikaris

Flag Rate for arterial po2 is 60% for lower limit (80mmHg) Art po2 Cumulative and around 10% for upper limit in OP (Flag Rate) Much higher high po2 flags in IP (>50%) due to oxygen and assisted ventilation (NZ,NSW ABG RI red dashed lines) ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT Courtesy K.Sikaris SEALS SEALS ISTAT Radiometer SSWPS Radiometer, Siemens istat PO 2 [mmhg] 83-108 83-108 80-105 75-100 80-100 83-108 75-100 75-100 75-100 69-116 80-105 80-100

Art ica Distributions Ionised calcium shows broad distribution. Courtesy K.Sikaris

Art ica Cumulative (Flag Rate) Flag Rate using 1.10 1.25 would be 30% at LRL and 5% at URL (NZ,NSW ABG RI red dashed lines) Courtesy K.Sikaris ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS RAPIDLAB PATH QLD (all devices) North Radiometer ISTAT North GEM West Radiometer, ISTAT SEALS Radiometer SEALS ISTAT SSWPS Radiometer, Siemens istat ica ++ [mmol/l] 1.15-1.30 1.15-1.29 1.12-1.32 1.15-1.32 1.1-1.4 1.15-1.32 1.12-1.30 1.04-1.24 1.15-1.30 1.1-1.3 1.12-1.32 1.15-1.29

Art SBIC Distributions SBIC is lower in inpatients (appropriate?) Courtesy K.Sikaris

Art SBIC Cumulative (Flag Rate) Flag rate for metabolic acidosis using 22 mmol/l cutoff is 10% for OP and 25% in inpatients Flag Rate for metabolic alkalosis is 15% for OP and <10% in inpatients. (NZ,NSW ABG RI red dashed lines) Courtesy K.Sikaris

How are the ABG RI s used diagnosis and monitoring (sick people not surprised at high flag rates) not used for screening generally what is the cut off with flag rates what is the clinical response to the gas result? Who can contribute What is the ideal clinician group Respiratory, ED. Clinical decision points may be different to the RI Interpreted as part of a pattern don t interpret pco2 without ph and bicarbonate

What now? Roger has presented the New Zealand ABG data We have seen some of the NSW data last year based on survey results. ABG state of the art, flag rates 10-20% or greater Melbourne 2011-2017 flag rates differences NSW Reference intervals by consensus For Discussion NZ and NSW ABG RI s are now the same Are these values candidates for harmonised RI s?

VENOUS BLOOD GAS Gus Koerbin Adjunct Professor, University Of Canberra, Faculty of Health Visiting Fellow, ANU, College of Health and Medicine

WHAT ARE WE GOING TO DISCUSS? Some additional venous data New Zealand and NSW VBG RI ph: 7.3-7.4 pco2: 40-50 mmhg Bicarbonate: 22-28 mmol/l ica: 1.15-1.30 mmol/l Summary

BGAS Database 2001-2017 Art Ven Ven% Total DanEmerg 1,888 262 12.2% 2,150 DanICUf 32,054 1,045 3.3% 32,054 DanICUm 37,659 947 2.5% 37,659 EpwEmerg 871 8 0.9% 871 EpwICU 29,519 0 0.0% 29,519 FreeCCU 57,593 3,215 5.6% 57,593 FreeICU 43,514 109 0.3% 43,514 OutPat 5,317 39 0.7% 5,317 Ward 27,435 81 0.3% 27,435 All 235,850 5,706 2.4% 236,112 Courtesy K.Sikaris

Venous ph Cumulative (Flag Rate) Insufficient Outpatient venous data for ph distribution. 60% flag rate at 7.35 (ABG LRL) for venous OP gases Red dashed lines NZ/NSWHP VBG RI: 7.30-7.40 Green dashed lines NSW RI study: 7.29-7.41 Courtesy K.Sikaris

Venous pco2 Cumulative (Flag Rate) If using the same 35 45 mmhg limits, the resp acidosis flag rate would increase from 25% (arterial) to 45% (venous) To maintain a similar rate rate to arterial flag rate (25%), the upper pco2 limit would need to be increase from 45 to 50. Conversely, to maintain arterial resp alkalosis arterial flag rate (15%), the lower limit would need to increase from 35 to about 37 mmhg. Red dashed lines NZ/NSWHP VBG RI: 40-50 mmhg Green dashed lines NSW RI study: 38-61 mmhg Courtesy K.Sikaris

Venous po2 Cumulative (Flag Rate) Flag Rate for 25-55 mmhg would be about 10% at each end. NZ/NSWHP VBG RI: N/A Green dashed lines NSW RI study:15-64 mmhg Courtesy K.Sikaris

Venous SBIC Cumulative (Flag Rate) Flag Rate for metabolic acidosis will increase from 10% to 20% is using the same cut-off for venous as arterial. Red dashed lines NZ/NSWHP VBG RI: 22-28 mmol/l (=HRI for plasma) Green dashed lines NZ/NSW RI study: 22-32 mmol/l Courtesy K.Sikaris

VBG Reference Interval Study on Radiometer ABL800 series analysers (NSW Health, Prince of Wales Hospital) Dixon-Reed (Non-Para) Flagging rate (Melbourne patients) ph 7.29 7.41 ~ 10% at both limits po2 15-64 <5% pco2 38 61 15% LRL, 10% URL Bicard 23.4 30.8 ~5% at both limits ica 1.16 1.32 20% LRL, <5% URL Courtesy R Horvath

Summary where to now? Are there any significant method differences? CLSI: if population and analysers similar then can adopt harmonised RI s Venous Is it better to have some reference intervals that are venous specific, than none at all or using inappropriate arterial RI s? How much more work needs to be done for adoption of harmonised RI s (venous and arterial)? Have we got enough data to suggest RI s for some analytes undertaken in ABG analysis? Are the NZ/NSW ABG and VBG reference intervals suitable as candidates for harmonised RI s