blood gas - aacb
TRANSCRIPT
BLOOD GAS (ARTERIAL AND VENOUS
Gus Koerbin
Adjunct Professor, University Of Canberra, Faculty of Health
Visiting Fellow, ANU, College of Health and Medicine
AACB Harmonisation meeting 10-11 May 2018, Sydney
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 Pathology experience
• Gus Koerbin • Some additional venous data • Summary
AACB Harmonisation meeting 10-11 May 2018, Sydney
Some introductory questions
AACB Harmonisation meeting 10-11 May 2018, Sydney
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?
AACB Harmonisation meeting 10-11 May 2018, Sydney
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,
AACB Harmonisation meeting 10-11 May 2018, Sydney
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
AACB Harmonisation meeting 10-11 May 2018, Sydney
Recap of 2017
• RCPA QAP
• Survey of labs and industry arterial RI’s
AACB Harmonisation meeting 10-11 May 2018, Sydney
pH ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS
RAPIDLAB PATH QLD
(all devices)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology 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
SIEMENS RAPIDLAB
PATH QLD (all devices)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology West
Radiometer, ISTAT
SEALS Radiometer
SEALS ISTAT
SSWPS Radiometer,
Siemens iSTAT
PCO2 [mmHg] 35-45 35-48 (M) 32-45 (F)
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)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology West
Radiometer, ISTAT
SEALS Radiometer
SEALS ISTAT
SSWPS Radiometer,
Siemens iSTAT
PO2 [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)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology 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 Pathology 2011-2017 flag rates
differences
AACB Harmonisation meeting 10-11 May 2018, Sydney
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
AACB Harmonisation meeting 10-11 May 2018, Sydney
Over to Roger
AACB Harmonisation meeting 10-11 May 2018, Sydney
Arterial blood gas (Flagging rates)
Gus Koerbin
Adjunct Professor, University Of Canberra, Faculty of Health
Visiting Fellow, ANU, College of Health and Medicine
AACB Harmonisation meeting 10-11 May 2018, Sydney
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.
AACB Harmonisation meeting 10-11 May 2018, Sydney
AACB Harmonisation meeting 10-11 May 2018, Sydney
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
NSW Health Pathology Agreed ABG Reference Interval
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 Pathology) 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
AACB Harmonisation meeting 10-11 May 2018, Sydney
Location (Sick) Melbourne Pathology: 2001-17
Courtesy K.Sikaris
AACB Harmonisation meeting 10-11 May 2018, Sydney
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)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology 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
Courtesy K.Sikaris
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 SIEMENS
RAPIDLAB PATH QLD
(all devices)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology West
Radiometer, ISTAT
SEALS Radiometer
SEALS ISTAT
SSWPS Radiometer,
Siemens iSTAT
PCO2 [mmHg] 35-45 35-48 (M) 32-45 (F)
35-45 35 - 45 35-45 32-48 35-45 35-45 35-45 32-45 35-45 35-45
Courtesy K.Sikaris
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
Art pO2 Cumulative (Flag Rate)
Flag Rate for arterial pO2 is 60% for lower limit (80mmHg) and around 10% for upper limit in OP 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)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology West
Radiometer, ISTAT
SEALS Radiometer
SEALS ISTAT
SSWPS Radiometer,
Siemens iSTAT
PO2 [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
Courtesy K.Sikaris
Art iCa Distributions Ionised calcium shows broad distribution.
Courtesy K.Sikaris
Art iCa Cumulative (Flag Rate)
ARTERIAL > 18 Y Possible RI RADIOMETER ISTAT IL SIEMENS
RAPIDLAB PATH QLD
(all devices)
Pathology North
Radiometer ISTAT
Pathology North GEM
Pathology 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
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
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
AACB Harmonisation meeting 10-11 May 2018, Sydney
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 Pathology 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?
AACB Harmonisation meeting 10-11 May 2018, Sydney
VENOUS BLOOD GAS
Gus Koerbin
Adjunct Professor, University Of Canberra, Faculty of Health
Visiting Fellow, ANU, College of Health and Medicine
AACB Harmonisation meeting 10-11 May 2018, Sydney
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
AACB Harmonisation meeting 10-11 May 2018, Sydney
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 Pathology, Prince of Wales Hospital)
Dixon-Reed
(Non-Para)
Flagging rate (Melbourne
Pathology 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
AACB Harmonisation meeting 10-11 May 2018, Sydney
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
AACB Harmonisation meeting 10-11 May 2018, Sydney