ABG.pdf-study about abg interpretation in icu

Study about abg

1. INTRODUCTION
Anarterialbloodgasmeasurementprovides
valuableinformationaboutthebloodpHand
thepartialpressuresofarterialcarbon
dioxide(PaCO
2)andoxygen(PaO
2).
Mostanalyserscalculateserumbicarbonate
(HCO
3
-
)andthebaseexcess.Some
analysersalsomeasure electrolytes,
haemoglobin,glucose,lactate,andother
analytes.

2. Arterialbloodgasisabloodtestthatis
performedusingbloodfromanartery.It
involvespuncturinganarterywithathin
needleandsyringeanddrawingasmall
volumeofblood

3. Therelativelylowincidenceofmajor
complications,itsabilitytobeperformedat
bedside,anditsrapidanalysismakeitan
importanttooltodirectandredirectthe
treatmentofthepatientespinpatientwho
arecriticallyilltodeterminegasexchange
levelsinthebloodrelatedtorespiratory,
metabolicandrenalfunction.

4. DEFINITION
Itisaproceduretomeasurethepartial
pressureofoxygenandcarbondioxide
(CO2)gasesandthepH(Hydrogenion
concentration)inarterialblood.

5. PURPOSE
To evaluate the acid base level in the blood
To diagnose and evaluate respiratory disease
To assess the integrity of the ventilator
control system
To evaluate the efficiency of pulmonary
gaseous exchange
To monitor the respiratory therapy

6. INDICATION
Critically ill or deteriorate unexpectedly—for
example, because ofsepsis or multiorgan
failure
Uncontrolled diabetes mellitus
Identification of metabolic, respiratory and
acid base disorder

7. Assessment oftheresponseto
therapeuticinterventionssuchas
mechanicalventilationinapatientwith
respiratoryfailure
Thesignificancechangeinventilator
modeorFiO2
Anysignofrespiratorydistress
Aftertheextubation

8. CONTRAINDICATION
Local infection or distorted anatomy at
the potential puncture site
Severe coagulopathy
Anticoagulation therapy with warfarin,
heparin and derivatives

9. EQUIPMENT
Disposable syringe, 2ml with swab.
needle no. 22/23
Heparin injection
Methylatedspirit swab
Ice pack

10. PRECAUTION
Syringeshouldbeheparinizedbefore
sampleiscollected;clottingshouldbe
avoided
Thesyringeshouldbefreefromairboth
beforeandaftersampleiscollected
Fortransportationthesyringeshouldbe
capped,placeonicepack,andimmediately
sentforthelaboratoryanalysis

12. PROCEDURE
1.Explaintheproceduretothepatient
2.Takethevitalsigns
Hyperthermiaandhypothermiainfluence02release
fromhemoglobin.
2 . Wash hands
3. Assemble equipments on bed side
4. Put on gloves
5. Assemble needle to syringe
a. keep needle sterile
b. eject excess heparin and air bubbles, if using syringe
with liquid heparin.

13. 6. Palpate the radial ,brachial or femoral artery
Select Site
Palpate the right and left radials arterial
pulse and visualize the course of the artery
Pick strongest pulse
a. Radial artery is always the first choice and
should be used because of it provides
collateral circulation
-if radial pulse weak on right, move to left
-if pulse on left weak, then try brachial
Note: If puncturing the radial artery,perform
allentest to determine if collateral circulation
is present

14. ALLENTEST

15. ALLENTEST

16. POSITIVERESULTS

17. b. Brachial used as alternative site
c. Femoral is the last choice in normal
situations
7. For the radial site ,place a small towel roll
under the patient’s wrist

18. 9.The needle is at a 45 to 60 degree angle
to the skin surface and is advanced in to
the artery .
1o. once the artery is punctured ,arterial
pressure will push up the hub of the
syringe and a pulsating flow of blood will
fill the syringe

21. 10.Afterbloodisobtained,withdrawthe
needleandapplyfirmpressureoverthe
puncturewithadrysponge
11.Removeairbubblesfromsyringeand
needleusesafetysyringesystemfor
closure
12.Placethecappedsyringeinthe
containerofice

22. 13.Maintainfirmpressureonthepuncture
sitefor5minutes
14.Ifthepatientisonanticoagulant
medication,applydirectpressureover
puncturesitefor10-15minuteandthen
applyafirmpressuredressing

23. POST PUNCTURE

24. COMPONENTS OF THE ABG
Pao
2 =The partial pressure of oxygen that is dissolved
in arterial blood 80-100 mm Hg.
HCO
3-=The calculated value of the amount of
bicarbonate in the blood 22 –26 mmol/L
PCO
2=The amount of carbon dioxide dissolved in
arterial blood 35–45 mmHg
pH=Measurement of acidity or alkalinity, based on the
hydrogen (H+) 7.35 –7.45
SAO
2 =The arterial oxygen saturation >95%

25. NORMALARTERIALANDVENOUSBLOODGAS
VALUES
Parameter Arterial Venous
pH 7.35-7.45 7.35-7.45
Paco2 35-45mmhg 40-45mmhg
Bicarbonate(HCO3) 22-26 mEq/L( MMOL/L) 22-26 mEq
pao2 80-100 mmhg 40-50 mmhg
Oxygen saturation 96-100% 60-85%

26. ACID BASE DISORDER
Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis

27. DEFINITIONS
Metabolicacidosis
Metabolicacidosisisaclinicaldisturbance
characterizedbyalowpH(increasedH+
concentration)andalowplasmabicarbonate
concentration.Itcanbeproducedbyagainof
hydrogenionoralossofbicarbonate
•Metabolicalkalosis
Metabolicalkalosisisaclinicaldisturbance
characterizedbyahighpH(decreasedH+
concentration)andahighplasmabicarbonate
concentration.Itcanbeproducedbyagainof
bicarbonateoralossofH+

28. RESPIRATORY ACIDOSIS
Respiratoryacidosisisaclinicaldisorder
inwhichthepHislessthan7.35andthe
PaCO2isgreaterthan42mmHg.
Itmaybeeitheracuteorchronic.
Respiratoryacidosisisalwaysdueto
inadequateexcretionofCO2with
inadequateventilation,resultingin
elevatedplasmaCO2levelsandthus
elevatedcarbonicacid(H2CO3)levels

29. RESPIRATORYALKALOSIS
Respiratory alkalosis is a clinical condition in
which the arterial pH is greater than 7.45
and the PaCO2 is less than 38 mm Hg.
As with respiratory acidosis, acute and
chronic conditions can occur.
Respiratory alkalosis is always due to
hyperventilation, which causes excessive
“blowing off” of CO2 and, hence, a decrease
in the plasma carbonic acid concentration.

31. INTERPRETATIONS
1.BloodPh(7.35-7.45)
-highindicatesalkalosis
-Lowindicatesacidosis
2.Paco2(35-45mmhg)
>45mmhg-respiratoryacidosis
<45mmhg-respiratoryalkalosis

32. 3.Pao2(80-100mmhg)
Thepartialpressureofo2thatisdissolvedinarterial
blood
4.Hco3(22-26meq/lit)
Thecalculatedvalueoftheamountofbicarbonatein
thebloodstream.
5.Baseexcess(-2to+2meq/l)
>+3=metabolicalkalosis
<-3=metabolicacidosis
6.Sao2(95%-100%)

34. INTERPRETATION BY TIC
TAC TOE METHOD

35. 1.Knowthenormalvalues
KnowthenormalandabnormalABGvalues
whenyoureviewthelabreports.They’re
fairlyeasytoremember:forpH,the
normalvalueis7.35to7.45;35-45
forpaCO
2;and22-26forHCO
3.

36. 2.DetermineifpHisunderacidosisor
alkalosis
Nextthingtodoistodeterminethe
acidityoralkalinityofthebloodthrough
thevalueofpH.ThepHlevelofahealthy
humanshouldbebetween7.35to7.45.
Thehumanbodyisconstantlystrivingto
keeppHinbalance.
pHlevelbelow7.35isacidosis
pHlevelabove7.45isalkalosis

38. 3.Determineifacid-baseisrespiratory
ormetabolic
Nextthingyouneedtodetermineis
whethertheacidbaseisRespiratoryor
Metabolic.
paCO
2= Respiratory
HCO
3= Metabolic

39. 4. Remember ROME
Still, it all boils down to mnemonics. The
mnemonic RO-ME.
Respiratory Opposite
When pH is up, PaCO
2is down = Alkalosis
When pH is down, PaCO
2is up = Acidosis
Metabolic Equal
When pH is up, HCO
3is up = Alkalosis
When pH is down, HCO
3is down = Acidosis

40. 5. Tic-Tac-Toe
And yes, ABG problems can be solved
work using the tic-tac-toe method. All you
have to do is make a blank chartsimilar to
this:

42. 6. Mark the Chart
Using the lab result values, mark them on
your tic-tac-toe. Let’s begin with this sample
problem:
pH: 7.26, paCO
2: 32, HCO
3: 18
Using the normal values reference chart in
the first step, determine where the values
should be under in the tic-tac-toe.

43. In the given example, the solution is as
follows:
pH of 7.26 is LOW = ACID so place pH
under Acid
paCO
2of 32 is LOW = BASE so place
paCO
2under Base
HCO
3of 18 is LOW = ACID so place HCO
3
under Acid

45. 7.Matchitup
Inthisstep,determineatwhichcolumn
matchesupwiththepH.Inthegiven
example,HCO
3goeswithpH.HCO
3is
consideredMetabolic(showninstep3),
andbothareunderAcid,sothisexample
impliesMetabolicAcidosis.

47. 8.Determinecompensation
ThelaststepistodetermineiftheABG
isCompensated,PartiallyCompensated,or
Uncompensated.Here’sthetrick:

48. If pH is NORMAL, PaCO
2and HCO
3are both
ABNORMAL = Compensated
IfpHisABNORMAL, PaCO
2andHCO
3are
bothABNORMAL =PartiallyCompensated
IfpHisABNORMAL, PaCO
2orHCO
3is
ABNORMAL =Uncompensated
ThereforethisABGisMETABOLIC
ACIDOSIS,PARTIALLYCOMPENSATED .

49. By applying the steps above, interpret the
following ABGs:
pH:7.44, PaCO
2: 30, HCO
3:21
pH is NORMAL = NORMAL so place pH under
Normal
PaCO
2is LOW = BASE so place PaCO
2under
Base
HCO
3is LOW = ACID so place HCO
3under
Acid

50. *Sincetheacidityofthebloodisdeterminedby
thevalueofthepH,determinewhetherthenormal
pHisSLIGHTLYACIDICorSLIGHTLYBASIC.
Inthisexample,pHisNORMALbutSLIGHTLY
BASICthereforeitisALKALOSIS.
InthiscasePaCO
2goeswithpH.PaCO
2is
consideredRespiratory(showninstep3),andboth
areunderBasic,sothisexampleimplies
RespiratoryAlkalosis.TheHCO
3isalsoabnormal.
WhenpHisNORMALandPaCO
2andHCO
3are
both ABNORMAL, itindicatesFULL
COMPENSATION .

52. THANK YOU