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![Physiological significant
• Flat upper part acts as a buffer-
• PO2 can drop to 80mmHg, yet Hb remained highly saturated (96%) with
oxygen keeping the arterial [O2] high despite impairment in saturation in the
lungs
• Steep lower part allows large O2 unloading and maintain O2 diffusion
gradient (from capillary to cell) by only a small drop in PO2](https://image.slidesharecdn.com/gastransport-221106062350-a67dca3a/75/Gas-Transport-pptx-22-2048.jpg)
![Oxygen content
• 98% is carried bound to Hb in RBC, only 2% of O2 in arterial blood is
present as dissolved O2
• One gram of Hb can combine with 1.34 ml O2 when 100% saturated
• Functional Hb saturation= [HbO2] x ( [HbO2] + [DeoxyHb]
(1 gm pure Hb binds 1.39mls O2)
• Fractional saturation = ( [HbO2] x 100/total [Hb] )
where total [Hb] = [HbO2] + [DeoxyHb] + [metHb] + [COHb]
(Physiological value ~ 1.34 to 1.37 ml.O2/gmHb)](https://image.slidesharecdn.com/gastransport-221106062350-a67dca3a/75/Gas-Transport-pptx-31-2048.jpg)
![• Total O2 content of arterial blood
CaCO2 = [1.34x(Hb)xSaO2] + [PaCO2 x kO2]
• CaCO2=O2 content (mlO2/dl Blood)
• Hb= hemoglobin concentration (g/dl)
• SaO2= O2 saturation of Hb
• kO2= O2 solubility constant (0.003ml O2/mmHg/dl of blood)
• Normal blood contains 15 gm of Hb/dl of blood
• CaCO2= (1.34x15x1) + (0.003x100)
= 20.4 mls/dl blood
• Thus normal O2 content is about 20.4ml O2/ dl of blood
(if 100% saturated)](https://image.slidesharecdn.com/gastransport-221106062350-a67dca3a/75/Gas-Transport-pptx-32-2048.jpg)
![O₂ Consumption by cell ~250mlsO₂/min
• Arterial point PaO₂ 100mmHg, SaO₂97.5% = 19.9mls O₂/dL
• Venous point PaO₂ 40mmHg, SaO₂ 75%
CaCO2 = [1.34x(Hb)xSaO2] + [PaCO2 x kO2]
= 15.1 + 0.12
= 15.22 O₂/dL
O₂ Consumption 19.9.-15.2= 4.7mls O₂/dL
~ 5x50=250mls O₂/min](https://image.slidesharecdn.com/gastransport-221106062350-a67dca3a/75/Gas-Transport-pptx-33-2048.jpg)
![• Oxygen Flux equation
oxygen flux = chemical O2 delivery + Dissolved O2 delivery
= [CO x (Hb) x SaO2 x k] + [CO x PaO2 x 0.003]
= [50 x 15 x 0.99 x 1.34] + [50 x 100 x 0.003]
= 995 + 15
= approx 1000 mls O2/ min
k – Huffner’s number (1.34mlO2/gm.Hb)
CO in dl/min; Hb in gm/dl](https://image.slidesharecdn.com/gastransport-221106062350-a67dca3a/75/Gas-Transport-pptx-35-2048.jpg)
![Transport of gases carbon dioxide and oxygen [Autosaved].pptx](https://cdn.slidesharecdn.com/ss_thumbnails/transportofgasesautosaved-250324055730-f2aabc7a-thumbnail.jpg?width=640&height=640&fit=bounds)
![PAIN ASSESSMENT IN INTENSIVE CARE UNIT edited[1].pptx](https://cdn.slidesharecdn.com/ss_thumbnails/painassessmentinintensivecareunitedited1-241015133245-77e2642f-thumbnail.jpg?width=640&height=640&fit=bounds)
Gas Transport.pptx
- 1. Gas Transport Dr IsmaSyarina Ismail Moderator : Dr Wan Fadzlina
- 2. OUTLINE • Oxygen cascade •Gas transport • Oxygen • Carbon Dioxide • Oxygen flux
- 3. Ventilation of thelungs supplies O₂ to the alveolus Diffusion of O₂ across the alveolus to the pulmonary capillaries O₂ carriage by blood ( Hb or dissolved in plasma) Diffusion from capillary to miochondria
- 4. OXYGEN CASCADE • Describethe sequential reduction in Po₂ from atmosphere to cellular mitochondria (site of consumption)
- 5.
- 6. Alveolar gas equation PAO2= PIO2 – PACO2 / R = 150 – (40/0.8) = 100mmHg • PACO2 = Alveolar partial pressure of oxygen • PIO2 = Inspired partial pressure of oxygen • PACO2 = Alveolar partial pressure of carbon dioxide • RQ = Respiratory quotient = CO2 produced/ O2consumed = 0.8 • Respiratory exchange ratio
- 8. Arterial Blood PO₂ •Source of contribution • Blood from bronchial and Thebesian vein drain directly into the pulmonary vein, avoiding pulmonary capillaries • V/Q mismatch – blood not fully oxygenated as it passes through poorly ventilated areas of the lung eg, pulm pathology
- 9. • 3 factorsmy cause the Po₂ in the pulmonary vein < PAO2 1. V/Q mismatch 2. Shunt 3. Diffusion impairment Increase Alveolar-arterial (A-a) gradient
- 11. GAS TRANSPORT OXYGEN TRANSPORT DissolvedO₂ (2%) + Chemical O₂ (98%)
- 12. DISSOLVED O₂ • ObeysHenry’s law : the amount dissolved gas is proportional to the partial pressure, Pa • At T of 37°C, plasma contains 0.003ml O₂/mmHgPo2
- 13. O₂ CARRIAGE BYHb • Characteristics: • Reversible • Positive cooperative
- 15.
- 16. • Hemoglobin isa complex molecule with a molecular weight of 64,500 • The protein globin has a tetrameric structure contains four polypeptide chains • Each of it is attached to a heme (iron porphyrin) • Center ferrous ion • Each hb molecule can bind with four oxygen molecules • The chain are of two types, alpha and beta • Hemoglobin A (normal adult Hb): 2α 2β
- 17. • Differences intheir amino acid sequences give rise to various type of human hemoglobin • Hemoglobin F (fetal): 2α 2γ • Higher affinity to oxygen
- 18. • Hemoglobin S(sickle): has valine instead of glutamic acid in the beta chains • Deoxygenated form is poorly soluble and crystallizes within the red cell • Cell shape changes from biconcave to crescent or sickle shaped with increased fragility and a tendency to thrombus formation
- 19. • Methemoglobin • Ferrousion (Fe2+) oxidised to ferric (Fe3+) form by various drugs including nitrites, sulfonamides and acetanilid or congenital cause in which the enzyme methemoglobin reductase is deficient within the red blood cell.
- 20. Oxygen Dissociation Curve(ODC) Sigmoid shape: 1.Allosteric modulation 2.Cooperative binding
- 21. P50 • The partialpressure of oxygen at which the oxygen carrying protein is 50% saturated • Normal p50 in adult hemoglobin is 26.6mmHg • Lie at the steepest part of the curve, thus most sensitive point to detect the shift of the curve • Index of oxygen affinity • P50 HbA = 26.6mmHg • P50 HbF = 18mmHg • P50 Myoglobin = 2.75mmHg • The lower the P50 the higher the affinity towards O₂
- 22. Physiological significant • Flatupper part acts as a buffer- • PO2 can drop to 80mmHg, yet Hb remained highly saturated (96%) with oxygen keeping the arterial [O2] high despite impairment in saturation in the lungs • Steep lower part allows large O2 unloading and maintain O2 diffusion gradient (from capillary to cell) by only a small drop in PO2
- 24. Bohr Effect • Theeffect of CO2 and H+ (pH) toward the affinity of Hb for oxygen • ↑CO2, H+ will cause ↓Hb affinity for O2, favour unloading, right shifted ODC
- 31. Oxygen content • 98%is carried bound to Hb in RBC, only 2% of O2 in arterial blood is present as dissolved O2 • One gram of Hb can combine with 1.34 ml O2 when 100% saturated • Functional Hb saturation= [HbO2] x ( [HbO2] + [DeoxyHb] (1 gm pure Hb binds 1.39mls O2) • Fractional saturation = ( [HbO2] x 100/total [Hb] ) where total [Hb] = [HbO2] + [DeoxyHb] + [metHb] + [COHb] (Physiological value ~ 1.34 to 1.37 ml.O2/gmHb)
- 32. • Total O2content of arterial blood CaCO2 = [1.34x(Hb)xSaO2] + [PaCO2 x kO2] • CaCO2=O2 content (mlO2/dl Blood) • Hb= hemoglobin concentration (g/dl) • SaO2= O2 saturation of Hb • kO2= O2 solubility constant (0.003ml O2/mmHg/dl of blood) • Normal blood contains 15 gm of Hb/dl of blood • CaCO2= (1.34x15x1) + (0.003x100) = 20.4 mls/dl blood • Thus normal O2 content is about 20.4ml O2/ dl of blood (if 100% saturated)
- 33. O₂ Consumption bycell ~250mlsO₂/min • Arterial point PaO₂ 100mmHg, SaO₂97.5% = 19.9mls O₂/dL • Venous point PaO₂ 40mmHg, SaO₂ 75% CaCO2 = [1.34x(Hb)xSaO2] + [PaCO2 x kO2] = 15.1 + 0.12 = 15.22 O₂/dL O₂ Consumption 19.9.-15.2= 4.7mls O₂/dL ~ 5x50=250mls O₂/min
- 34. OXYGENT FLUX • Amountof O₂ delivered to the peripheral tissues per minutes • In healthy young adult, the tissues O₂ delivery is ~ 1000mls O₂/min • Tissues extract 250mls O₂/min (body O₂ consumption) • 750mls O₂ return to right heart
- 35. • Oxygen Fluxequation oxygen flux = chemical O2 delivery + Dissolved O2 delivery = [CO x (Hb) x SaO2 x k] + [CO x PaO2 x 0.003] = [50 x 15 x 0.99 x 1.34] + [50 x 100 x 0.003] = 995 + 15 = approx 1000 mls O2/ min k – Huffner’s number (1.34mlO2/gm.Hb) CO in dl/min; Hb in gm/dl
- 36. CₐO₂ (O₂ content)X CO (cardiac output) = O₂ delivery ,DO₂ (Oxygen flux) How to increase CₐO₂ and DO₂ • Increase circulating Hb • Maintain high oxygen saturation • Increase dissolved oxygen by increase partial pressure of oxygen • Optimise HR and rhytm (sinus ) • Optimise SV (preload/contractality) • Maintain perfusion pressure to ensure organ oxygen delivery (afterload)
- 37. • The amountof O₂ in the blood is determined by : • Amount of dissolved O₂ • Amount of Hb in the blood • Affinity of Hb to the O₂
- 38. GAS TRANSPORT CARBON DIOXIDETRANSPORT Dissolved CO2 (5%) Bicarbonate (90%) Carbamino compounds (5%)
- 39. Carbamino compound • Formedfrom CO₂ reaction with • Terminal amino group of protein • Amino groups in the side chains of arginine and lysine
- 42. Chloride shift • ExcessHco3 leaves the RBC in exchange of Chloride
- 43. Haldane Effect • Referto the effect of O2 on affinity of Hb to CO2 • Removal of O2 from Hb increases the affinity of Hb for CO2. • Favour the loading of CO2 in the tissue level • Arterial blood contains 48mls of CO2 at PCO2 of 40mmHg • Mixed venous blood contains 52 mls of CO2 at PCO2 of 46mmHg
- 45.