4.2 Oxygen dissociation curve Flashcards

Question

Volume pressure & flow during normal breathing Draw 3 curves on page 131 Draw curve showing change intrapleural pressure during normal TV Curve showing corresponding change in alveolar pressure Gas flow in trachea

Answer 1

4.15 0 intrapleural during quiet breathing IPP v Time -5 at start inspiration d.t elastic recoil lungs fall in IPP during inspiration d/t increas elastic recoil and fall alveolar pressure Alveolar P v time decrease alveolar pressure est driving pressure If no airway resstiance - alverolar pressure stay 00 thru-out inspiration - Airway resistance is delta P between alveoli and mouth / flow Major site resistant - medium sized bonrhci most pressure drop occurs airways up to 7th gen <20% d/t airways <2mm diameter gas flow in trachea during quiet breathing

Answer 2

Aim increase oxygen patient lung as a buffer against hypomaeia during apneoa Aim displace N from FRC and replace O2 Denitrogenaiton effective oxygen in lung increased substatn increase can occur rapidly

Answer 3

FRC supine 30mlkg 2.1l in 70kg adult normal con 13% o2 = 270mls little more than mins supply ``` if preoxy al gas eqn pred max of about 660 760-47 -40/.8 87% oxygen alveol and 1825 o2 at frc 7 mins oxygen at consump 250mls min ```

Answer 4

Yes - hypervent 2 factors 1 rate wawshout N increase - signifcant effect speeds up Condeq decrease alv PCo2 FRC sml amt addit oxygen pred alveolar g eqn

Answer 5

``` FRC Blood Dissolved in fluiod myoglobi VC inspir - increase ``` lungs 270-> 1825 Blood 820-> 910 tussye 45->50 Nyi gkib 200 -> 200 min cellular change substant increase d/t lungs total sotres breathing room air 1335 supine increase ~~ 3l breathing 100%

Answer 6

Increase content blood d.t increase sat hb a+ v sides increase dissovled .3 at 100mmhg -> 1.8 at 600mmhg Only parts blood increase diss o2 - lheart and stem artery veins not increase on 100% extra dissolved in blood only 15mls Incr ven po2 hb sat in veins high normal increase carriage both art and venous side 70mls extra in veins and rheart d/t igher sat hb total increase oxygen store in blood 80-95ml small compared increased stores in lung tissue po2 mi alter little increase in o2 stores myoglob low p50 sat little alter small icrease po2

Answer 7

vitally - present cell participate rxn dissovle o2 diffused capilary to cell across placenta doesnt contrib to delivery bt has vital role in rxn cells

Answer 8

Mitochodn oxidative phospho - largest con ~90% total use of o2 cell oxy reacts w. H produce metabolic water in final step electron tpor tchain catlysed cytochrome oxidsae

Answer 9

Sit sm aponeic oxyugen lungs full oxygen airway opne - no vent oxygen pulm cap blood cont normal no excretion co2 art pco2 rise rapidy as much 55mmhg Reasons 1 wash thru mix venou blood haldane effect - pco2 constant pco2 will rise - d/t rise in sats Inevitable abrupt increase cbf - espec if difficult and prolonged smyp stim -addit stress cbf and icp

Answer 10

Alveolar Po3 rises to high value - calc from alveolar gas equiaton PaO2 = PiO2 - PaCO2/R WHere R is reps exchange ratio Pio2 is inpsired pp Assuming paco2 is same value as art pco2 PiO2 = 760 -47 713 for oxyygen full sat wiht vapor 37 pao2 713 - 40/.8 = 663 sp wpi;d [redict value 663 arterial lower d/t venous admix (inlcude v/q mm) Probably over 600 mmhg in health young adult

Answer 11

PaCo2 - not be affected - value proportional tissue CO2 production and inversely proportional to alveolar venitlation - unaffected pN2 - decrease as N2 being washed out of body decrease low levels if breathing 100% oxygen continue Nitrogen lungs washed out quickly - dentitrogenation

Answer 12

O2 40mmhg - hb 75% sat CO2 - 46

Answer 13

Pco2 is about 46mmHg rise in Po2 not sufficient to alter increase in deoxy if po2 in venous blood was 100mmhg or more - hyperbaric oxyen then hb remain fully aR Pco2 rise to about 55mmHg - d/t absence haldane effect As mix venous not much higher 100% oxygen - hldane imporant and mix venus pco2 not much affected

Answer 14

Po2 slightly eleavted 48->50

Answer 15

Answer -appreciation difference oxygen content and oxygen partial pressure Po2 600mhg in art blood - high partial pressure - oxygen content rise art blod small As Hb almost fully sat at Po2 100mmHg Increase PO2 >100 cannt add any more oxygen hb AMount oxygen dissolved in blood directed related to PP Amt oxygen dissolvedat 600 is x6 dissollved at 100mmhg Amt O2 dissolved 100 at PO2 100 - .003 x 100 = 3mls amt 100mls at 600 .003 x 600 - 1.8 henrys law Hb not start release oxygen until po2 <100mmHg because of shape of ODC Oxygen released from hb but po2 not drop to 40 mix blood because signif contib dissolve oxygen mix venous po2 48-50

Answer 16

no dissolved oxygen not suffficent supply needs of all the tissues some dissociation of oxygen from Hb will laways occur Mean capillary Po2 be only slightly elevated from normal not sufficient to cause toxic effect in periphery Alveolar cells exposed to high Po2 with prolonged exporsure -s ome oxygen tox in lung

Answer 17

Major oxygenation problem Must be d/t significant shunt Other major cause hypoxaemia in ITU is V/Q mm if this where the cause - vent 100% = high po2 arterial po2 should rise over 500mmhg if v/q mismatching presnet without coex shunt rise art po2 slow - if many units with low v/qs With 100% art po2 rise to high level in other 4 causes hypoxaemia hypoventilation low inspired o2 diffusion block diffusion hypoxaemia (exercise at altitude)

Answer 18

Mech is diffusion gas down PP grad from gas pT into blood and pleural cap Most cases ptx high Po2 than cap blood o2 diff down into pleural cap blood PTX decrease size total pressure resmain same @1atm Loss volume d/t xoygen absorption concentrating effect on all gasses reamin icnreasees gradient acouring resabso gases oxygen PP increase by eefect reabson continue and size cont decrease conc effect important till all gas reabsorbed Key understand 3 point above 1 gas move down diffusion conc grad Total pressure in ptx doesnt vary much beacuse voulme change totral press ~~1atm Becaume volume redcution and main constant pressure in PTx abso gas down conc grad has conc effect on remain gas increase pp gases and maintain gradient keeps process untull all reabasorb PTTX may increase in size cert ciurm room air to 70%N2o NO DIFFUSION DOWN CONC INT ptx would increase size difference movemnt n2o and N N2o diffusion fastr than N diffuse out Increase size decreasePP grad other gases Gas compostion of ptx vary on orignal source if orig room air pco2 low and grad cause entry co2 capillary great reabs oxygen - decrease in vol and conc effect - conc effect increase PP of all gases present

Answer 19

Water vapour Ph20 remains 47mmh - and svp 37 Eliminate nitrogen cap glood grad fave reab N larger Mixed venous po2 slightly increase breathing 100% not much affect in gradient facour oxygen reab offse effect dentropgenation PTX reabsorb faster breathing 100% and this dt assos dentrogenation

Answer 20

Blue discolouration sking d/t presence excess amt desat hb in blood cyanosis detectable clinically when blood contains 5gdl of deoxy hb

Answer 21

Cyanosis clin apprtly 1.5gdl meth-haem present in cap blood clinical significant lower than 5 g dl deoxy reqd

Answer 22

Produced in hb when haem irons converted Ferrous Fe 2 -> Ferric Fe3 oxidation may be caused by some drugs or metabolites eg metab of prilocaine prduces otoludine - which can oxidise haem iron Met-haem doesnt bind oxygen Redcells contain enzyme methab reductase which reduce ferric back o ferrous requires NADH cytochrome b5 as cofacor oxidation of ferrous ion in b occurs at 3% day

Answer 23

Iron in deoxyhb is in ferrous form oxyhb is different - partial tfer electron from iron to oxygen Oxy hb has a superoxyferrihaem Fe3O2 Unloading of oxygen restore the ferrous form howerver rarely oxygen leaves as a superoxide radiacal o2 and the iron is left in the ferric stat - methhb

Answer 24

In additio to NADH meth hb redcuate red cell contrain another enx can reduce hb Enz is NADPH methhb reductase under normal coniditon is responible few percent of daily methb reduction. In presence of methylene blue - amt hb reduction d/t enzyme increase enzyme directly reduces methylen blue - reduce form methylne blue non enzymatically reduce mehthb

Answer 25

Require 5gdl deoxy hb cap blood person sever anmaei hb <5 - yanosis never be prseent with less severe cyanosis require high level desat beofre present

Answer 26

Salte grey blue discol skin - insoluble silver albuminate occurs ingents silver salts long time rare could be confused cyanosis

Answer 27

Page 138 Draw flow volume loop flow is on y volme is on x TLC start rapidly increase flow towards 8l sec, then desending limb expiratory curve from onset closure to RV Effor indep potion most descending part - occuring during expiration -part descling lumb from onset airway closure down to RV max poss flow rate at any particul volume on x defined by max expiratory curve reason flow not exceed cause of dynamic airway compression

Answer 28

Consider forced expiration increase intrapleral pressure - tmitted to alveoli - alveolar pressure >mouth pressure (atm) - airway open gas flows out lung thru airways down pressure gradient Might be thouhgt - greater effort during expiration larger increase intrapleural pressure - greater rise in alveolar pressure - increase gradient alvoelar and mouht pressure increase expiratory flow rate Happens to limit particular max flow ossible depend lung volume at that instant - indicated on max exp flow vol loop reason flow limitation related design chest part airwys in thoracic cavity - like alveoli airways also exposed increaed intrapleural pressure during forced expiration - larger pressure acts squeee alveoi - also acts compress airway initiall held open airway pressure inside great than intrapleural because resistance airway presure inside airway decrease preogressively further particular airway from alveoli finally reach point airway pressure and intraplreal are equal distal to equal pressure point airway collapse Known as straling resistor driving pressure flow differnece pressure alveolar and intrpleural rather pressure diff alveolus and mouth dirivng foce - same even with incraed expiratory effort Max flow constant each partic lung vol and decrease as lung vol decreases

Answer 29

Increased airway resistance of intrapulmonary airways -airway pressure drops rapidly Increased compliance - results reduced driving pressure Expiration from initla low volume - vecause reduced driving pressure - ie alveolar intrapleural press diffc decrease forced expiration w/ emphysema - causes more ponounced dynamic airway compression audible wheeze - may be presesnt during noraml TV no wheze airway closed - no flow

Answer 30

TOtal lung voule high - chest over expand loop left shift max flow rate reduced total vol expire less fvc descending limb - may be concanve

Answer 31

Intramyocardial pressurre limits perfusion lv during systele Lung - alveolre pressure is external pressure - west zones any organ has capule - oedema casues increase tissue pressure pericaridal effsuion impar vr AND filling icp - limits cbf pregnant uterus contracts vacval compression - supine hypotension pregn muslce pump mech leg - promo vr increase intraabdo pressure - bowel bladder emypty tampomade pulm vessel during vaslavla incrase IOP _ glaucoma oedema muslce in CT ocompar tight plaster cast - oedema tissue injury