This document discusses the oxyhemoglobin dissociation curve. It provides background on oxygen transport by hemoglobin and factors that influence the curve. Key points include: - Hemoglobin transports oxygen through cooperative binding of up to 4 oxygen molecules per heme-globin molecule. - The sigmoidal dissociation curve arises from cooperative binding - as one oxygen binds it increases affinity for others. - Factors like pH, CO2, temperature can shift the curve left or right, altering oxygen unloading in tissues. - Fetal hemoglobin has a higher affinity, helping oxygen transfer to the fetus in utero. Myoglobin also has higher affinity and acts as an oxygen storage in muscle.

1. OXYHEMOGLOBINOXYHEMOGLOBIN
DISSOCIATIONDISSOCIATION
CURVECURVE
Dr. S. ParthasarathyDr. S. Parthasarathy
MD., DA., DNB(anaes), MD (Acu),MD., DA., DNB(anaes), MD (Acu),
Dip. Diab. DCA, Dip. Software statisticsDip. Diab. DCA, Dip. Software statistics
PhD (physio)PhD (physio)
Mahatma Gandhi medical college andMahatma Gandhi medical college and
research institute , puducherry – Indiaresearch institute , puducherry – India

2. HOPE THIS WOULD BE A VERYHOPE THIS WOULD BE A VERY
USEFUL LECTUREUSEFUL LECTURE
OR ATLEAST IT WILL BE AOR ATLEAST IT WILL BE A
---------FUL LECTURE---------FUL LECTURE

3. ANAESTHETISTS DOANAESTHETISTS DO
PREANAESTHETIC CHECK UPPREANAESTHETIC CHECK UP
What is important ??What is important ??

5. LAVOISIER AND LAPLACELAVOISIER AND LAPLACE
17791779
 INTAKE OF SOME GASES WASINTAKE OF SOME GASES WAS
RESPIRATION AND IT PRODUCEDRESPIRATION AND IT PRODUCED
SOME ACIDSOME ACID
 OXYOXY= ACID= ACID
 GENGENE= PRODUCER.E= PRODUCER.

6. ATMOSPHERIC AIRATMOSPHERIC AIR
 NITROGEN = 78%NITROGEN = 78%
 OXYGEN = 21%OXYGEN = 21%
 ARGON = 0.9%ARGON = 0.9%
 COCO 22 = 0.03%= 0.03%
 TRACES OF HELIUM ,NEON ANDTRACES OF HELIUM ,NEON AND
KRYPTONKRYPTON

7. BAROMETRIC PRESSUREBAROMETRIC PRESSURE
PPBB = 760 mm Hg= 760 mm Hg
 760760 × 21/100 =× 21/100 =160 mm Hg160 mm Hg..
(P(PBB × Fio2)× Fio2)
HUMIDIFIED IN THEHUMIDIFIED IN THE
AIRWAYS.AIRWAYS.
P H2O = 47 mmHg.P H2O = 47 mmHg.
PIO2 = (760-47) × 21/100 =PIO2 = (760-47) × 21/100 =

8. ALVEOLUS -- CO2 DILUTESALVEOLUS -- CO2 DILUTES
PA0PA022 = PIO= PIO22 – PACO– PACO22 / RQ/ RQ
= 150 - 45 == 150 - 45 = 105105
RQ = RESPIRATORY QUOTIENTRQ = RESPIRATORY QUOTIENT
COCO22 PRODUCED / OPRODUCED / O22 CONSUMEDCONSUMED

10. ALVEOLUSALVEOLUS
↓↓ OO22
PLASMAPLASMA
↓↓ OO22
DISSOLVED OXYGENDISSOLVED OXYGEN
↓↓
TRANSFERRED TO HbTRANSFERRED TO Hb
PaPa OO22 100 mm Hg100 mm Hg

11.  160 -150-105-100- 40-25-4160 -150-105-100- 40-25-4
 oxygen cascadeoxygen cascade

13. OXYGEN CARRIAGE INOXYGEN CARRIAGE IN
TWO FORMSTWO FORMS
 DISSOLVED —DISSOLVED — 0.3 ml / 100ml0.3 ml / 100ml
 Very less but.,Very less but.,
 IT ISIT IS IMPORTANTIMPORTANT
– IT DETERMINES PaO2IT DETERMINES PaO2
– IT TRANSFERS O2 TOIT TRANSFERS O2 TO
HAEMOGLOBIN.HAEMOGLOBIN.
– IT IS THIS SMALL QUANTITY WHICHIT IS THIS SMALL QUANTITY WHICH
DIFFUSES TO TISSUES FIRST.DIFFUSES TO TISSUES FIRST.

14. HEMOGLOBINHEMOGLOBIN
 1 gm of Hb carries 1.34 ml-1.39 ml of O1 gm of Hb carries 1.34 ml-1.39 ml of O22
 19.5-19.7 ml oxygen / 100 ml19.5-19.7 ml oxygen / 100 ml
 Dissolved + Hb oxygen= 20 mlDissolved + Hb oxygen= 20 ml
 200 ml / litre or200 ml / litre or 1000 ml / 5 litre1000 ml / 5 litre

15. 1000 ml1000 ml oo22 suppliedsupplied
 250 ml consumed250 ml consumed
 750 ml returned750 ml returned
 SvO2 75%SvO2 75%
 Oxygen flux =Oxygen flux = CARDIAC OUTPUTCARDIAC OUTPUT
× 1.34 × Hb ×× 1.34 × Hb ×
SATURATIONSATURATION

16. HEMOGLOBIN=HEMOGLOBIN=
HEMEHEME+GLOBIN+GLOBIN
 FOURFOUR HEME MOLECULES +GLOBINHEME MOLECULES +GLOBIN
(FOUR CHAINS )(FOUR CHAINS )
 2 ALPHA AND 2 BETA CHAINS.2 ALPHA AND 2 BETA CHAINS.
 FOUR HEMESFOUR HEMES
(FERROPROTOPORPHYRIN ) CAN(FERROPROTOPORPHYRIN ) CAN
ATTACH 4 OXYGEN MOLECULESATTACH 4 OXYGEN MOLECULES
 O2 + FERROUS = FERRICO2 + FERROUS = FERRIC →→
SATURATION → OXYGENATED HbSATURATION → OXYGENATED Hb

19. COOPERATIVECOOPERATIVE
EFFECT.EFFECT.
 OXYGEN ENTRY TO Hb PROMOTESOXYGEN ENTRY TO Hb PROMOTES
FURTHER ENTRY BY INCREASING THEFURTHER ENTRY BY INCREASING THE
AFFINITY UPTO 500 TIMES TO SUCKAFFINITY UPTO 500 TIMES TO SUCK
MORE O2----MORE O2----POSITIVE COOPERATIVEPOSITIVE COOPERATIVE
EFFECT.EFFECT.
 IN DOWNLOADING IN TISSUES.IN DOWNLOADING IN TISSUES.
REVERSE ISREVERSE IS NEGATIVENEGATIVE

20. Parrots and parentsParrots and parents
 Hemoglobin and oxygen act a little like parentsHemoglobin and oxygen act a little like parents
and children. When all are living at home (i.e.and children. When all are living at home (i.e.
hemoglobin is fully saturated) then the parentshemoglobin is fully saturated) then the parents
don’t want any to leave:don’t want any to leave:
 but once one has flown the nest (i.e.but once one has flown the nest (i.e.
dissociated from hemoglobin) – parents find itdissociated from hemoglobin) – parents find it
progressively easier to let go.progressively easier to let go.

21.  What this means that the conformation of theWhat this means that the conformation of the
hemoglobin molecule depends on the number ofhemoglobin molecule depends on the number of
molecules bound:molecules bound:
 as one molecule of oxygen becomes unbound,as one molecule of oxygen becomes unbound,
the affinity for the others falls [and vice-versa].the affinity for the others falls [and vice-versa].
 This is represented by the oxyhemoglobinThis is represented by the oxyhemoglobin
dissociation curve.dissociation curve.

22. Why the curve isWhy the curve is
sigmoid ??sigmoid ??
 COOPERATIVE EFFECT CAUSESCOOPERATIVE EFFECT CAUSES
THE CURVE TO BE SIGMOID.THE CURVE TO BE SIGMOID.
 RR FORM (RELAXED) –FORM (RELAXED) –
OXYGENATEDOXYGENATED
 TT FORM (TAUT) - DE OXYGENATEDFORM (TAUT) - DE OXYGENATED

24. BEFORE THE CURVE – ABEFORE THE CURVE – A
BREAKBREAK
 A LADY PATIENT ENTERED AA LADY PATIENT ENTERED A
DOCTOR’S (MALE) CABIN AND SAIDDOCTOR’S (MALE) CABIN AND SAID
 ““ SIR, CAN I ASK MY HUSBANDSIR, CAN I ASK MY HUSBAND
ALSO TO COME INSIDE.”ALSO TO COME INSIDE.”
 DOCTOR :DOCTOR : “ BELIEVE ME, I AM A“ BELIEVE ME, I AM A
GENTLEMANGENTLEMAN.”.”

25.  LADY PATIENT :LADY PATIENT :
““SIR I BELIEVE YOU ., BUT ISIR I BELIEVE YOU ., BUT I
DON’T BELIEVE MYDON’T BELIEVE MY
HUSBAND AND YOURHUSBAND AND YOUR
NURSE OUTSIDE”NURSE OUTSIDE”

27. CURVE OF PaO2 TO SaO2CURVE OF PaO2 TO SaO2
PaO2 SaO2
27 50 (P50)
40 75 (VENOUS)
60 90
100 98

29. P 50 = 27 , Rt and leftP 50 = 27 , Rt and left

30.  SHIFT TO RIGHT = PSHIFT TO RIGHT = P5050 > 27> 27
 SHIFT TO LEFT= PSHIFT TO LEFT= P5050 < 27< 27
 RIGHT SHIFTRIGHT SHIFT AT ANY PaO2 LESSAT ANY PaO2 LESS
AFFINITY ,LESS SATURATIONAFFINITY ,LESS SATURATION
INCREASED H + IONSINCREASED H + IONS
(ACID)(ACID)
INCREASED PCO2,INCREASED PCO2,
INCREASED TEMPINCREASED TEMP

33. BOHR EFFECTBOHR EFFECT
 ↑↑ PCO2 AND ACIDOSIS CAUSE RT.PCO2 AND ACIDOSIS CAUSE RT.
SHIFTSHIFT
 H + IONS BIND TO GLOBIN CHAINSH + IONS BIND TO GLOBIN CHAINS
TO EFFECT A CONFORMATIONALTO EFFECT A CONFORMATIONAL
CHANGE IN HEME ATTACHMENTCHANGE IN HEME ATTACHMENT
FAVOURING UNLOADING OF OFAVOURING UNLOADING OF O22
( WE WANT TO HAPPEN IN( WE WANT TO HAPPEN IN
TISSUES.)TISSUES.)

34. HALDANE EFFECTHALDANE EFFECT
 DEOXYGENATED BLOODDEOXYGENATED BLOOD
CAN PICK UP MORE COCAN PICK UP MORE CO22
 THINK OF TISSUES :THINK OF TISSUES :
 UNLOADING O2UNLOADING O2→→ DEOXYGENATEDDEOXYGENATED
BLOODBLOOD → PICKS UP MORE CO2→ PICKS UP MORE CO2

35.  15 DAYS OLD BLOOD CAN15 DAYS OLD BLOOD CAN
CAUSE DECREASED 2-3CAUSE DECREASED 2-3
DPG LEVELS TO SHIFTDPG LEVELS TO SHIFT
LEFT--LESS UNLOADINGLEFT--LESS UNLOADING
AND MORE AFFINITYAND MORE AFFINITY
(KENNEDY EFFECT)(KENNEDY EFFECT)
 24-48 HOURS TO BECOME24-48 HOURS TO BECOME

36. What is the role of 2-3What is the role of 2-3
DPG ??DPG ??
 In the deoxygenated T conformer, a cavityIn the deoxygenated T conformer, a cavity
capable of binding 2,3-BPG forms in the centercapable of binding 2,3-BPG forms in the center
of the molecule. 2,3-BPG can occupy this cavityof the molecule. 2,3-BPG can occupy this cavity
stabilizing the T state. Conversely, when 2,3-stabilizing the T state. Conversely, when 2,3-
BPG is not available, or not bound in the centralBPG is not available, or not bound in the central
cavity, Hb can be converted to HbO2 morecavity, Hb can be converted to HbO2 more
readily.readily.

37. Useful increase in 2-3Useful increase in 2-3
BPGBPG
 HIGH ALTITUDE.HIGH ALTITUDE.
 COPDCOPD
 CYANOTIC HEART DISEASECYANOTIC HEART DISEASE
 SEVERE ANEMIAS.SEVERE ANEMIAS.

38. FETAL HbFETAL Hb

40. Fetal Hb (higher affinity)Fetal Hb (higher affinity)
 Umbilical venous bloodUmbilical venous blood
(20-25 mmHg O2)(20-25 mmHg O2)
 DOUBLE BOHR EFFECTDOUBLE BOHR EFFECT
 Transfer of acids from fetalTransfer of acids from fetal
blood to maternalblood to maternal
intervillous spaces—intervillous spaces—
maternal Hb more acidicmaternal Hb more acidic
Rt shift—more unloadingRt shift—more unloading
to fetus…fetal alkalosisto fetus…fetal alkalosis
shift to left-Hb F moreshift to left-Hb F more
affinity-more loadingaffinity-more loading
Pa
O2
Hb A
Sao2
Hb F
Sao2
22 40 75

41. MYOGLOBINMYOGLOBIN

43. MYOGLOBIN (HIGHERMYOGLOBIN (HIGHER
AFFINITY)AFFINITY)
 HYPERBOLIC CURVE –NOHYPERBOLIC CURVE –NO
COOPERATIVE EFFECT.COOPERATIVE EFFECT.
 IF MYO REPLACES ADULT Hb ITIF MYO REPLACES ADULT Hb IT
NEEDS DOUBLE THE AMOUNT ANDNEEDS DOUBLE THE AMOUNT AND
WE WILL BEWE WILL BE 12 POUNDS HEAVIER12 POUNDS HEAVIER..
 BUT THERE(IN MUSCLE) WE NEEDBUT THERE(IN MUSCLE) WE NEED
A STORAGE SPECIALIST AS ADULTA STORAGE SPECIALIST AS ADULT
Hb IS TRANSPORT SPECIALIST.Hb IS TRANSPORT SPECIALIST.

44. OXYGEN FLUX = CARDIACOXYGEN FLUX = CARDIAC
OUTPUTOUTPUT ×O2 CONTENT ---×O2 CONTENT ---
((MAINLY 1.34MAINLY 1.34 × Hb ×× Hb ×
SATURATIONSATURATION ))
 IN A PERIOPERATIVE OR AIN A PERIOPERATIVE OR A
CRITICAL CARE SETTING MAXIMISECRITICAL CARE SETTING MAXIMISE
O2 DELIVERY BYO2 DELIVERY BY MAXIMISING-MAXIMISING-
 1.CARDIAC OUTPUT.1.CARDIAC OUTPUT.
 2.Hb.2.Hb.
 3.SATURATION.3.SATURATION.

45. HOPE THIS WOULD BE A VERYHOPE THIS WOULD BE A VERY
USEFUL LECTUREUSEFUL LECTURE
OR ATLEAST AOR ATLEAST A CCOOLLOOUURRFFUULL
ONEONE

46. THANK YOUTHANK YOU