applied physiology & chemistry rt 210 unit b. mechanics of ventilation: ventilation &...
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Applied Physiology & Applied Physiology & ChemistryChemistry
RT 210RT 210
Unit BUnit B
Mechanics of Ventilation: Mechanics of Ventilation: Ventilation & RespirationVentilation & Respiration
Ventilation is air movement in and out of the Ventilation is air movement in and out of the lungs to allow external respiration to occurlungs to allow external respiration to occur
Respiration is gas exchange across a Respiration is gas exchange across a permeable cellular membranepermeable cellular membrane
External respiration is gas exchange External respiration is gas exchange between alveolar gas (between alveolar gas (airair) and capillaries ) and capillaries ((bloodblood))
Internal respiration is gas exchange Internal respiration is gas exchange between capillaries and the tissuesbetween capillaries and the tissues
The Lung - Thorax The Lung - Thorax RelationshipRelationship
Two opposing forcesTwo opposing forces Lungs tend to collapse due to elasticityLungs tend to collapse due to elasticity Chest wall tends to spring outChest wall tends to spring out Linked together by the pleura Linked together by the pleura
Negative pressure -4 to -5 cm H2ONegative pressure -4 to -5 cm H2O Parietal pleura lines chest wallParietal pleura lines chest wall Visceral pleura covers lungVisceral pleura covers lung Potential space between with small amount of Potential space between with small amount of
lubricant/pleural fluid between layerslubricant/pleural fluid between layers
Normal ventilation Normal ventilation pressurespressures
Inspiration, (intrapleural = -10 cm Inspiration, (intrapleural = -10 cm H2O, intrapulmonary -3 cm H2O)H2O, intrapulmonary -3 cm H2O)
Diaphragm contracts and flattensDiaphragm contracts and flattens Chest cavity expandsChest cavity expands Negative intrapulmonary pressureNegative intrapulmonary pressure Negative transairway pressureNegative transairway pressure Gas flows in through the mouthGas flows in through the mouth
Normal ventilation Normal ventilation pressurespressures
Expiration, (intrapleural = -5 cm H2O, Expiration, (intrapleural = -5 cm H2O, intrapulmonary = +3 cm H2O)intrapulmonary = +3 cm H2O)
Diaphragm relaxesDiaphragm relaxes Chest cavity recoils and decreases in sizeChest cavity recoils and decreases in size Slight positive intrapulmonary pressureSlight positive intrapulmonary pressure Gas flows out through the mouth Gas flows out through the mouth
Physics of VentilationPhysics of Ventilation
Law of LaplaceLaw of Laplace P = 2 ST/rP = 2 ST/r surface tension tends to collapse alveolisurface tension tends to collapse alveoli Surfactant allows different sized alveoli to Surfactant allows different sized alveoli to
be connected without smaller emptying into be connected without smaller emptying into the larger alveoli and collapsingthe larger alveoli and collapsing
PhospholipidPhospholipid Decreases surface tension of the alveoli Decreases surface tension of the alveoli Allows critical volume to be variable from alveoli Allows critical volume to be variable from alveoli
to alveolito alveoli
Compliance-measures Compliance-measures dispensability of the lungdispensability of the lung
Compliance of the Lung = change in Compliance of the Lung = change in volume divided by change in volume divided by change in pressure pressure
)(
)(
2OHcmpressure
litersvolumeCL
Compliance-measures Compliance-measures dispensability of the lungdispensability of the lung
Total compliance = lung and thorax Total compliance = lung and thorax (lung is not measured out of thorax)(lung is not measured out of thorax)
Pulmonary compliance = 0.2L/cm H2OPulmonary compliance = 0.2L/cm H2O Thoracic compliance = 0.2L/cm H2OThoracic compliance = 0.2L/cm H2O Total compliance = 0.1 L/cm H2OTotal compliance = 0.1 L/cm H2O
thoracicCpulmonaryCtotalC
111
Compliance-measures Compliance-measures dispensability of the lungdispensability of the lung
pressurepeak
volumeDynamic
Pressure is peak pressure during gas flow
pressureplateau
volumeStatic
Compliance-measures Compliance-measures dispensability of the lungdispensability of the lung
Decreased or less compliance seen in:Decreased or less compliance seen in: Pulmonary consolidationPulmonary consolidation Pulmonary edemaPulmonary edema PneumothoraxPneumothorax Abdominal distensionAbdominal distension ARDSARDS Pulmonary fibrosisPulmonary fibrosis Thoracic deformitiesThoracic deformities Complete airway obstructionComplete airway obstruction
Compliance-measures Compliance-measures dispensability of the lungdispensability of the lung
Compliance increasesCompliance increases Alveolar distensionAlveolar distension Alveolar septal defectAlveolar septal defect Obstructive disorders-CBABEObstructive disorders-CBABE
C = Cystic FibrosisC = Cystic Fibrosis B = BronchitisB = Bronchitis A = AsthmaA = Asthma B = BronchiectasisB = Bronchiectasis E = EmphysemaE = Emphysema
Compliance is inversely related to Compliance is inversely related to elastanceelastance Elastance is the property of resisting deformationElastance is the property of resisting deformation
Resistance Resistance
Resistance = Resistance =
Flow
essurePr
ResistanceResistance
LaminarLaminar Poiseuille’s Law states that flow rate Poiseuille’s Law states that flow rate
varies directly with radius of a tubevaries directly with radius of a tube Small changes in airway radius will Small changes in airway radius will
dramatically affect flow and resistancedramatically affect flow and resistance ½ decrease in diameter increases resistance by ½ decrease in diameter increases resistance by
16 times16 times Turbulent (non laminar or eddy flow)Turbulent (non laminar or eddy flow)
The higher the flow the more resistanceThe higher the flow the more resistance Resistance is also directly proportional to gas Resistance is also directly proportional to gas
densitydensity
ResistanceResistance
TransitionalTransitional Tracheobronchial tree has both laminar Tracheobronchial tree has both laminar
and turbulent flow caused in part by the and turbulent flow caused in part by the directional changes in the conductive directional changes in the conductive airwayairway
Reynold’s numberReynold’s number Less than 2000 is laminar flowLess than 2000 is laminar flow 2000-4000 is laminar and turbulent or mixed 2000-4000 is laminar and turbulent or mixed
flowflow Greater than 4000 is turbulent flowGreater than 4000 is turbulent flow
ResistanceResistance
ViscosityViscosity Pressure GradientPressure Gradient Bernoulli’s PrincipleBernoulli’s Principle Coanda EffectCoanda Effect
Lung VolumesLung Volumes
Relate to lung/thorax relationship, Relate to lung/thorax relationship, compliance and surface tensioncompliance and surface tension
Four volumes and four capacitiesFour volumes and four capacities IRV - Inspiratory Reserve VolumeIRV - Inspiratory Reserve Volume
Maximum inhalation following quiet inhalationMaximum inhalation following quiet inhalation Normally 3.1 LNormally 3.1 L
VT - Tidal VolumeVT - Tidal Volume Volume inspired or expired during quiet Volume inspired or expired during quiet
breathingbreathing Normally 0.5LNormally 0.5L
Lung VolumesLung Volumes
Four volumes and four capacities Four volumes and four capacities (cont)(cont)
ERV - Expiratory Reserve VolumeERV - Expiratory Reserve Volume Maximum exhalation following quiet exhalationMaximum exhalation following quiet exhalation Normally 1.2LNormally 1.2L
RV - Residual VolumeRV - Residual Volume Gas remaining in lung after maximum exhalationGas remaining in lung after maximum exhalation Normally 1.2LNormally 1.2L
Lung VolumesLung Volumes
Capacities - consist of 2 or more Capacities - consist of 2 or more volumes or capacitiesvolumes or capacities
IC - Inspiratory CapacityIC - Inspiratory Capacity Made of IRV and VTMade of IRV and VT Maximum inhalation following quiet exhalationMaximum inhalation following quiet exhalation Normally 3.6LNormally 3.6L
FRC - Functional Residual CapacityFRC - Functional Residual Capacity Made of ERV and RVMade of ERV and RV Gas in lung following quiet exhalationGas in lung following quiet exhalation Normally 2.4L Normally 2.4L
Lung VolumesLung Volumes
Capacity (cont)Capacity (cont) VC - Vital CapacityVC - Vital Capacity
Made of IRV, VT, and ERVMade of IRV, VT, and ERV Maximum exhalation following a maximum Maximum exhalation following a maximum
inspirationinspiration Normally 4.8LNormally 4.8L
TLC - Total Lung CapacityTLC - Total Lung Capacity Made of IRV, VT, ERV and RVMade of IRV, VT, ERV and RV Gas in the lung following maximum inhalationGas in the lung following maximum inhalation Normally 6LNormally 6L
FRC and Lung ComplianceFRC and Lung Compliance FRC is most consistent volume - FRC is most consistent volume -
diaphragm at restdiaphragm at rest At FRC, equalization of opposing forces of At FRC, equalization of opposing forces of
pulmonary and thoracic elasticitypulmonary and thoracic elasticity As elasticity changes, FRC changesAs elasticity changes, FRC changes At FRC, intrapleural pressure is normal -5 cm At FRC, intrapleural pressure is normal -5 cm
H2OH2O At FRC, intrapulmonary pressure equals At FRC, intrapulmonary pressure equals
ambient pressureambient pressure With an increase in compliance, (decrease With an increase in compliance, (decrease
elasticity), an increase in ease of inspiration elasticity), an increase in ease of inspiration but difficulty in expirationbut difficulty in expiration
Decrease in compliance, decrease the ease of Decrease in compliance, decrease the ease of inspiration inspiration
Classification of VentilationClassification of Ventilation
VE = Minute VentilationVE = Minute Ventilation The amount of gas moved in 1 minuteThe amount of gas moved in 1 minute Calculated by VT times (*) fCalculated by VT times (*) f Can be measured by a respirometerCan be measured by a respirometer
Vane- Draeger, WrightVane- Draeger, Wright Volume bellows spirometerVolume bellows spirometer Venticomp bagVenticomp bag Vortex principle- Boum’s LS 75Vortex principle- Boum’s LS 75 Use a respirometer with a filter attached to Use a respirometer with a filter attached to
demonstrate measuring VEdemonstrate measuring VE
Classification of VentilationClassification of Ventilation
VD= Dead spaceVD= Dead space Part of min. ventilation is "wasted", does Part of min. ventilation is "wasted", does
not reach alveoli where external not reach alveoli where external respiration occursrespiration occurs
Anatomical (VDanat)Anatomical (VDanat) Fills space in the conductive airwaysFills space in the conductive airways
Alveolar (VDalv)Alveolar (VDalv) Alveoli that are not perfusionAlveoli that are not perfusion
Physiologic (VDphys)Physiologic (VDphys) All dead space combination of VDanat and VDalvAll dead space combination of VDanat and VDalv
Classification of VentilationClassification of Ventilation
Dead space (cont)Dead space (cont) MechanicalMechanical
Added dead spaceAdded dead space Normally 1 cc per pound ideal weight Normally 1 cc per pound ideal weight
(approx. 150cc)(approx. 150cc) Volume rebreathedVolume rebreathed
Classification of VentilationClassification of Ventilation
VA = Alveolar ventilationVA = Alveolar ventilation Gas in perfused alveoliGas in perfused alveoli Participates in external respirationParticipates in external respiration VA= (VT - VD)VA= (VT - VD)
Classification of VentilationClassification of Ventilation Terms relating to dead spaceTerms relating to dead space
Normal ventilationNormal ventilation Adequate ventilation to meet metabolic needsAdequate ventilation to meet metabolic needs
HypoventilationHypoventilation Decreased alveolar ventilationDecreased alveolar ventilation Can be caused by increased VD or decreased VTCan be caused by increased VD or decreased VT Ventilation less than that necessary to meet Ventilation less than that necessary to meet
metabolic needs; signified by a PCO2 greater metabolic needs; signified by a PCO2 greater than 45 mmHg in the arterial bloodthan 45 mmHg in the arterial blood
HyperventilationHyperventilation Increased alveolar ventilationIncreased alveolar ventilation Caused by decreased VD or increased VTCaused by decreased VD or increased VT Ventilation more than necessary to meet Ventilation more than necessary to meet
metabolic needs, signified by a PCO2 less than metabolic needs, signified by a PCO2 less than 35 mmHg in the arterial blood35 mmHg in the arterial blood
Ventilation and PerfusionVentilation and Perfusion
Ventilation = alveolar minute Ventilation = alveolar minute ventilationventilation
VA = (VT - VD)* fVA = (VT - VD)* f Perfusion = blood flow to the tissuesPerfusion = blood flow to the tissues
Ventilation and PerfusionVentilation and Perfusion External respiration = gas exchange External respiration = gas exchange
between the alveoli and capillariesbetween the alveoli and capillaries Carbon dioxide leaves bloodCarbon dioxide leaves blood Oxygen enters the bloodOxygen enters the blood Respiratory Quotient -unequal exchange of Respiratory Quotient -unequal exchange of
CO2 produced vs. oxygen uptake or utilizationCO2 produced vs. oxygen uptake or utilization
200 ml CO2 produced by 250 ml O2 used due to 200 ml CO2 produced by 250 ml O2 used due to normal metabolism in the Kreb’s cycle (CARC page normal metabolism in the Kreb’s cycle (CARC page
154 & 389).154 & 389).
8.0250
200
/5
/4
2
2
2
2 Oml
COmlor
Ovol
COvolRQ
Gas exchange unitGas exchange unit
Normal unitNormal unit Alveoli with capillary—relationship between Alveoli with capillary—relationship between
ventilation and gas flow are relatively equalventilation and gas flow are relatively equal Dead space unitDead space unit
ventilation without or in excess of perfusionventilation without or in excess of perfusion ShuntShunt
Perfusion without or in excess of ventilationPerfusion without or in excess of ventilation Silent unitSilent unit
No perfusion, no ventilationNo perfusion, no ventilation
Regional Differences in Regional Differences in Ventilation & PerfusionVentilation & Perfusion
More ventilation to the basesMore ventilation to the bases 4 times more ventilation to bases than apices4 times more ventilation to bases than apices
Due to gravity’s effect on pleural pressuresDue to gravity’s effect on pleural pressures On inspiration the transpulmonary pressure is On inspiration the transpulmonary pressure is
greater at the basesgreater at the bases More perfusion to basesMore perfusion to bases
Due to gravityDue to gravity 20 times more perfusion to bases than apices20 times more perfusion to bases than apices
Ventilation/Perfusion ratio (V/Q)Ventilation/Perfusion ratio (V/Q) V/Q = 4L alveolar minute volume 5L minute V/Q = 4L alveolar minute volume 5L minute
cardiac outputcardiac output Overall for the lung is 4:5 or 0.8Overall for the lung is 4:5 or 0.8
Regional Differences in Regional Differences in Ventilation & PerfusionVentilation & Perfusion
DiffusionDiffusion Whole Body Diffuision GradientsWhole Body Diffuision Gradients Determinants of Alveolar Gas TensionsDeterminants of Alveolar Gas Tensions Mechanism of DiffusionMechanism of Diffusion Systemic Diffusion GradientsSystemic Diffusion Gradients AbnormalitiesAbnormalities
Impaired oxygen DeliveryImpaired oxygen Delivery Impaired Carbon Dioxide RemovalImpaired Carbon Dioxide Removal
Shunting Shunting Unoxygenated blood entering the left Unoxygenated blood entering the left
side of the heartside of the heart Anatomical shuntAnatomical shunt
Normally 2-5% of cardiac outputNormally 2-5% of cardiac output Bronchial veins drains bronchial circulationBronchial veins drains bronchial circulation Pleural veins drains pleural circulationPleural veins drains pleural circulation
Thebesian veins drains heart circulationThebesian veins drains heart circulation
Absolute capillary shuntAbsolute capillary shunt Alveoli perfused but not ventilatedAlveoli perfused but not ventilated ““True Shunt”True Shunt” Refractory to O2 therapyRefractory to O2 therapy
ShuntingShunting
Relative capillary shuntRelative capillary shunt V/Q mismatchV/Q mismatch Areas where perfusion is in excess of Areas where perfusion is in excess of
ventilationventilation Physiological shuntPhysiological shunt
Sum of anatomical, absolute and relative shuntsSum of anatomical, absolute and relative shunts CausesCauses
Decrease in ventilationDecrease in ventilation An increase in perfusion (increased CO)An increase in perfusion (increased CO)
Dead SpaceDead Space "Wasted" ventilation"Wasted" ventilation TypesTypes
AnatomicalAnatomical Conducting airways in tracheobronchial treeConducting airways in tracheobronchial tree
Alveolar: Alveoli that have decreased perfusionAlveolar: Alveoli that have decreased perfusion Physiological: Sum of anatomical and alveolarPhysiological: Sum of anatomical and alveolar Mechanical – added dead spaceMechanical – added dead space CausesCauses
An increase in ventilationAn increase in ventilation A decrease in perfusion (decreased CO)A decrease in perfusion (decreased CO)
EffectEffect Increased VD will decrease VA if VE remains constantIncreased VD will decrease VA if VE remains constant
Effects of exercise & of high Effects of exercise & of high pressure environspressure environs
ExerciseExercise Increases CO2 production and O2 Increases CO2 production and O2
consumptionconsumption Aerobic versus anaerobicAerobic versus anaerobic
Oxygen consumption correlates to alveolar Oxygen consumption correlates to alveolar ventilationventilation
At rest 250ml rises to 3500ml/minute At rest 250ml rises to 3500ml/minute (untrained) to 5000ml/minute (trained (untrained) to 5000ml/minute (trained athlete)athlete)
PaO2, PaCO2 and pH remain constantPaO2, PaCO2 and pH remain constant
Effects of exercise & of high Effects of exercise & of high pressure environspressure environs
Exercise (cont)Exercise (cont) CirculationCirculation
Increased sympathetic impulses stimulates heart Increased sympathetic impulses stimulates heart rate and perfusion to working musclesrate and perfusion to working muscles
Frank-Starling mechanismFrank-Starling mechanism Maximal heart rateMaximal heart rate
Muscle Work, Oxygen Consumption, and Muscle Work, Oxygen Consumption, and Cardiac Output InterrelationshipsCardiac Output Interrelationships
The Training InfluenceThe Training Influence Body Temperature: Cutaneous Blood Flow Body Temperature: Cutaneous Blood Flow
RelationshipRelationship
Effects of exercise & of high Effects of exercise & of high pressure environspressure environs
High altitudeHigh altitude AcclimatizationAcclimatization Major cardiopulmonary responsesMajor cardiopulmonary responses
increased alveolar ventilation via peripheral increased alveolar ventilation via peripheral chemoreceptor stimulationchemoreceptor stimulation
Secondary polycythemia, increased RBC production Secondary polycythemia, increased RBC production due to low oxygen levelsdue to low oxygen levels
Development of respiratory alkalemia, due to the Development of respiratory alkalemia, due to the increased alveolar ventilation and carbon dioxide increased alveolar ventilation and carbon dioxide eliminationelimination
Increased oxygen diffusion capacity in native high Increased oxygen diffusion capacity in native high dwellers, due to increased lung sizedwellers, due to increased lung size
Effects of exercise & of high Effects of exercise & of high pressure environspressure environs
Major cardiopulmonary responses (cont)Major cardiopulmonary responses (cont) Increased alveolar arterial oxygen differenceIncreased alveolar arterial oxygen difference Improved ventilation perfusion ratioImproved ventilation perfusion ratio Increased cardiac output of non-acclimatized Increased cardiac output of non-acclimatized
individualsindividuals Increased pulmonary hypertension as a result of Increased pulmonary hypertension as a result of
hypoxic vasoconstrictionhypoxic vasoconstriction
SolutionsSolutions
DefinitionDefinition Concentration Concentration Osmotic pressureOsmotic pressure Quantifying solute content and activityQuantifying solute content and activity Calculating solute contentCalculating solute content Quantitative classification of solutionsQuantitative classification of solutions
Electrolytic Activity and Acid Electrolytic Activity and Acid Base BalanceBase Balance
Characteristics of acids, bases, and Characteristics of acids, bases, and saltssalts
Designation of acidity and alkalinityDesignation of acidity and alkalinity
Body Fluids and ElectrolytesBody Fluids and Electrolytes
FluidsFluids Electrolytes Electrolytes
Blood GasesBlood Gases
DefineDefine Kreb’s [TCA] CycleKreb’s [TCA] Cycle
Oxygen TransportOxygen Transport
DissolvedDissolved Henry's Law - weight of gas dissolving Henry's Law - weight of gas dissolving
in liquid is proportional to the partial in liquid is proportional to the partial pressure of a gaspressure of a gas
Bunsen solubility coefficient for O2Bunsen solubility coefficient for O2 0.023ml of O2 can be dissolved in 1ml of plasma 0.023ml of O2 can be dissolved in 1ml of plasma
at 37°C and 760mmHg PO2at 37°C and 760mmHg PO2 This allows us to determine the amount of O2 This allows us to determine the amount of O2
(expressed in ml) dissolved in 1ml of plasma (expressed in ml) dissolved in 1ml of plasma using the formula: 0.003 * PaO2using the formula: 0.003 * PaO2
(ex: PaO2 of 100 mmHg = 0.3ml of dissolved O2 (ex: PaO2 of 100 mmHg = 0.3ml of dissolved O2 in plasma)in plasma)
Oxygen TransportOxygen Transport
Graham's Law – rate of diffusion of a Graham's Law – rate of diffusion of a gas is directly proportional to its gas is directly proportional to its solubility coefficient and inversely solubility coefficient and inversely proportional to the square root of its proportional to the square root of its densitydensity
CO2 is 20 times more diffusible than O2CO2 is 20 times more diffusible than O2 CO is 200 times more diffusible than O2CO is 200 times more diffusible than O2 Hemoglobin’s affinity for CO is 200 times Hemoglobin’s affinity for CO is 200 times
more than for oxygen.more than for oxygen.
Oxygen TransportOxygen Transport
Combined with hemoglobinCombined with hemoglobin Carries the most oxygen to the tissuesCarries the most oxygen to the tissues Doesn't exert a gas pressureDoesn't exert a gas pressure Calculate 1.34 * Hb * SaO2Calculate 1.34 * Hb * SaO2 Total oxygen content is sum of Total oxygen content is sum of
dissolved and combineddissolved and combined
Oxygen TransportOxygen Transport
Oxyhemoglobin dissociation curve Oxyhemoglobin dissociation curve Curve is sigmoidal due to Hb affinity Curve is sigmoidal due to Hb affinity
for O2 at each of 4 binding sitesfor O2 at each of 4 binding sites Last site has less affinity than 2nd & 3rd Last site has less affinity than 2nd & 3rd In the steep portion minimal changes in In the steep portion minimal changes in
PO2 will cause drastic changes in PO2 will cause drastic changes in saturation and total O2 contentsaturation and total O2 content
P50 is where Hb is 50% saturated with O2 P50 is where Hb is 50% saturated with O2 and is normally a PaO2 of 27mm/Hgand is normally a PaO2 of 27mm/Hg
Oxygen TransportOxygen Transport
Oxyhemoglobin dissociation curve Oxyhemoglobin dissociation curve (cont)(cont)
A shift to right causes a decreased A shift to right causes a decreased affinity for O2, resulting in decreased affinity for O2, resulting in decreased saturation but increased O2 to tissues saturation but increased O2 to tissues
Factors causing shift to the rightFactors causing shift to the right Increased PCO2Increased PCO2 Increased H+ (decreased pH)Increased H+ (decreased pH) Increased 2, 3 DPGIncreased 2, 3 DPG Increased temperatureIncreased temperature
Oxygen TransportOxygen Transport
Oxyhemoglobin dissociation curve Oxyhemoglobin dissociation curve (cont)(cont)
A shift to the left causes increased affinity A shift to the left causes increased affinity for O2, resulting in increased saturation for O2, resulting in increased saturation but decreased O2 to the tissuesbut decreased O2 to the tissues
Factors causing shift to the leftFactors causing shift to the left Decreased PCO2Decreased PCO2 Decreased H+ (increased pH)Decreased H+ (increased pH) Decreased temperatureDecreased temperature Decreased 2, 3, DPGDecreased 2, 3, DPG
Oxygen TransportOxygen Transport Oxyhemoglobin dissociation curve Oxyhemoglobin dissociation curve
(cont)(cont) Bohr effect – the effect of H+ or CO2 on Bohr effect – the effect of H+ or CO2 on
Hb affinity for O2Hb affinity for O2 At lungs – PCO2 is lowAt lungs – PCO2 is low
Shifts curve to leftShifts curve to left Increased affinity for O2Increased affinity for O2 pH increased in lungs causing shift to the left with pH increased in lungs causing shift to the left with
an uptake of oxygen into the bloodan uptake of oxygen into the blood At tissues - PCO2 is highAt tissues - PCO2 is high
Shifts curve to the rightShifts curve to the right Decreases affinity for O2Decreases affinity for O2 pH decreased in tissue causing shift to right pH decreased in tissue causing shift to right
releasing oxygen to the tissuereleasing oxygen to the tissue
Shift to Left (increased affinity)
Shift to Right (decreased affinity)
H+ ( pH) H+ ( pH) PCO2 PCO2 Temperature Temperature
2-3 DPG 2-3 DPG P50 <27 P50 >27 ↑ SaO2 ↓ Sao2
Oxygen TransportOxygen Transport
Total O2 content is determined by Total O2 content is determined by adding the combined oxygen adding the combined oxygen content with the dissolved oxygen content with the dissolved oxygen contentcontent
CaO2 = (0.003 * PaO2) + (1.34 * Hb * CaO2 = (0.003 * PaO2) + (1.34 * Hb * SaO2)SaO2)
HypoxemiaHypoxemia
Deficiency of oxygen in the arterial Deficiency of oxygen in the arterial bloodblood
Causes of hypoxemiaCauses of hypoxemia Decreased alveolar oxygen tensionDecreased alveolar oxygen tension
Alveolar air equationAlveolar air equation
RQ
PaCOvaporOPHPBarOFPAO 2
2212 )(
HypoxemiaHypoxemia
Causes of hypoxemiaCauses of hypoxemia Alveolar hypoventilationAlveolar hypoventilation Decreased hemoglobin saturationDecreased hemoglobin saturation Alveolar hypoventilation due to V/Q Alveolar hypoventilation due to V/Q
abnormalitiesabnormalities Intrapulmonary shunting: blood going from Intrapulmonary shunting: blood going from
right to left heart without oxygenationright to left heart without oxygenation
HypoxemiaHypoxemia
Responses to hypoxemiaResponses to hypoxemia Increased ventilationIncreased ventilation Increased cardiac outputIncreased cardiac output TypesTypes
HypoxicHypoxic AnemicAnemic StagnantStagnant HistotoxicHistotoxic
HypoxiaHypoxia
Decreased oxygen to the tissuesDecreased oxygen to the tissues Hypoxemic Hypoxia or Ambient HypoxiaHypoxemic Hypoxia or Ambient Hypoxia
PaO2 decreasedPaO2 decreased Anemic Hypoxia or Hemic Hypoxia Anemic Hypoxia or Hemic Hypoxia
Hb decreasedHb decreased inability to accept O2 (CO poisoning)inability to accept O2 (CO poisoning)
Hb has 200 times more affinity for CO than O2Hb has 200 times more affinity for CO than O2 Normal HbCO is 0.5%Normal HbCO is 0.5% HbCO of 5-10% occurs after smokingHbCO of 5-10% occurs after smoking HbCO of 40-60% can cause deathHbCO of 40-60% can cause death
HypoxiaHypoxia
Stagnant Hypoxia or Circulatory HypoxiaStagnant Hypoxia or Circulatory Hypoxia Heart unable to deliver oxygenated blood to Heart unable to deliver oxygenated blood to
tissues (low CO)tissues (low CO) Histotoxic HypoxiaHistotoxic Hypoxia
cells unable to accept or use oxygen cells unable to accept or use oxygen (cyanide poisoning)(cyanide poisoning)
ResultsResults Anaerobic metabolismAnaerobic metabolism Production of lactic acids is a by product of Production of lactic acids is a by product of
CO2 metabolismCO2 metabolism
Alveolar-Arterial Oxygen Alveolar-Arterial Oxygen Difference P(A-a)O2Difference P(A-a)O2
Measurement of the pressure difference Measurement of the pressure difference between the alveoli and the arterial between the alveoli and the arterial bloodblood
In normal lungs O2 is readily transferred In normal lungs O2 is readily transferred from alveoli to blood and only a small PO2 from alveoli to blood and only a small PO2 difference is presentdifference is present
Diseased lungs often have larger P(A-a)O2 Diseased lungs often have larger P(A-a)O2 because of diffusion defectsbecause of diffusion defects
Has been used to estimate the percent Has been used to estimate the percent intrapulmonary shuntintrapulmonary shunt On 100% O2, every 50 mmHg difference in P(A-On 100% O2, every 50 mmHg difference in P(A-
a)O2 approximates a 2% shunta)O2 approximates a 2% shunt
Alveolar-Arterial Oxygen Alveolar-Arterial Oxygen Difference P(A-a)O2Difference P(A-a)O2
An increase in P(A-a)O2 is strictly An increase in P(A-a)O2 is strictly an indication of respiratory defects an indication of respiratory defects in oxygenation abilitiesin oxygenation abilities
Most respiratory dysfunctions that produce Most respiratory dysfunctions that produce hypoxemia are accompanied by an hypoxemia are accompanied by an increase in P(A-a)O2increase in P(A-a)O2
Normal value on room air is 10 to Normal value on room air is 10 to 15 mmHg15 mmHg
CO2 TransportCO2 Transport
Carbon DioxideCarbon Dioxide Produced from normal metabolismProduced from normal metabolism The burning of glucose with O2 is The burning of glucose with O2 is
carried in plasma and in red blood cellscarried in plasma and in red blood cells
CO2 TransportCO2 Transport
In plasmaIn plasma Dissolved: approximately 8% of CO2Dissolved: approximately 8% of CO2 As Bicarbonate (HCO3): As Bicarbonate (HCO3):
CO2 + H2O form carbonic acid (H2CO3)CO2 + H2O form carbonic acid (H2CO3) dissociates into bicarbonate and hydrogen ionsdissociates into bicarbonate and hydrogen ions Equation Equation H2O + CO2 = H2CO3H2O + CO2 = H2CO3H+ + HCO3¯H+ + HCO3¯
about 80% of C02 is transported as about 80% of C02 is transported as bicarbonatebicarbonate
Attached to plasma proteins about 12%Attached to plasma proteins about 12%
CO2 TransportCO2 Transport
In the red blood cellsIn the red blood cells DissolvedDissolved As HCO3¯As HCO3¯
HCO3¯ produced by hydrolysis of CO2HCO3¯ produced by hydrolysis of CO2 HCO3¯ diffuses out of cellHCO3¯ diffuses out of cell creates an electrical imbalancecreates an electrical imbalance Cl¯ enters the cell to bring balanceCl¯ enters the cell to bring balance called the chloride shift or Hamburger called the chloride shift or Hamburger
phenomenonphenomenon Attached to the Hb moleculeAttached to the Hb molecule
CO2 TransportCO2 Transport
Haldane EffectHaldane Effect The effect of O2 on CO2 transportThe effect of O2 on CO2 transport
At the lungs, PO2 is increased & CO2 is At the lungs, PO2 is increased & CO2 is unloaded off Hbunloaded off Hb
At the tissues, PO2 is decreased & CO2 is At the tissues, PO2 is decreased & CO2 is loaded on Hbloaded on Hb
CO2 TransportCO2 Transport
Terms relating to PaCO2Terms relating to PaCO2 Hypocapnia or hyporcarbiaHypocapnia or hyporcarbia
CO2 below 35 mmHgCO2 below 35 mmHg Hypercapnia or hypercarbiaHypercapnia or hypercarbia
CO2 above 45 mmHgCO2 above 45 mmHg EucapneaEucapnea
Normal CO2 (35-45 mmHg)Normal CO2 (35-45 mmHg)
Buffer Systems (Acid Base Buffer Systems (Acid Base Balance) Balance)
Purpose is to maintain the pHPurpose is to maintain the pH Prevent rapid changesPrevent rapid changes
Buffer systemsBuffer systems Open/BicarbonateOpen/Bicarbonate
Mainly the HCO3/H2CO3Mainly the HCO3/H2CO3 VentilatoryVentilatory About 60%About 60%
HbHb RenalRenal About 30%About 30%
Buffer Systems (Acid Base Buffer Systems (Acid Base Balance) Balance)
Closed/NoncarbonateClosed/Noncarbonate BloodBlood
IntracellularIntracellular Phosphates, proteins, sulfates and Phosphates, proteins, sulfates and
ammonia groupsammonia groups Physiological roles of buffer systemsPhysiological roles of buffer systems
BicarbonateBicarbonate NoncarbonateNoncarbonate
Henderson-Hasselbalch Henderson-Hasselbalch EquationEquation
pH = pk + logpH = pk + log
pk = 6.10 pk = 6.10 normally HCO3¯= 24 mEq/Lnormally HCO3¯= 24 mEq/L normally H2CO3 = 1.2 mEq/Lnormally H2CO3 = 1.2 mEq/L
log of 20 = 1.3log of 20 = 1.3 6.1 + 1.3 = 7.4 normal pH6.1 + 1.3 = 7.4 normal pH 10/1 = acidemia10/1 = acidemia 30/1 = alkalemia30/1 = alkalemia
)(
)(
32
3
COH
HCO
1
20
32
3
COH
HCO
Normal Values (Arterial)Normal Values (Arterial)
AbsoluteAbsolute RangeRange pHpH 7.47.4 7.35-7.457.35-7.45 PaCO2 PaCO2 40 mmHg40 mmHg 35-4535-45 PaO2PaO2 100 mmHg100 mmHg 80-10080-100 HCO3HCO3 24 mEq/L24 mEq/L 22-2622-26 BaseBase 00 00 + or – 2+ or – 2 HbHb 14 gm %14 gm % 12-1512-15 O2 SatO2 Sat 97.5 %97.5 % 95 - 100%95 - 100% O2 contentO2 content 20 volume %20 volume % 18-20 volume 18-20 volume
%%
Normal Values (Venous)Normal Values (Venous)
AbsoluteAbsolute pHpH 7.367.36 PvCO2PvCO2 4646 PvO2PvO2 4040 HCO3HCO3 2424 BaseBase 00 HbHb 14 14 O2 SatO2 Sat 75 75 O2 contentO2 content 15 volume %15 volume %
Acid Base EffectsAcid Base Effects
Increased CO2 causes a decreased Increased CO2 causes a decreased pHpH
Decreased CO2 causes an increased Decreased CO2 causes an increased pHpH
Increased HCO3 causes an increased Increased HCO3 causes an increased pHpH
Decreased HCO3 causes a Decreased HCO3 causes a decreased pHdecreased pH
CompensationCompensation
KidneysKidneys Excrete H+ which increase HCO3 to Excrete H+ which increase HCO3 to
compensate for an increased CO2compensate for an increased CO2 Excrete less H+ and more HCO3 to Excrete less H+ and more HCO3 to
compensate for decreased PCO2compensate for decreased PCO2 May take 3 days to compensateMay take 3 days to compensate Excess Hydrogen Ion excretion & role Excess Hydrogen Ion excretion & role
of urinary buffersof urinary buffers
CompensationCompensation
LungsLungs Increases CO2 to compensate for an Increases CO2 to compensate for an
increased HCO3 (short term only)increased HCO3 (short term only) PharmacologicallyPharmacologically
Administer sodium bicarbonate Administer sodium bicarbonate (NaHCO3) to increase pH(NaHCO3) to increase pH
Administer ammonium chloride Administer ammonium chloride (NH3Cl) to decrease pH(NH3Cl) to decrease pH
InterpretationInterpretation
Method for interpretationMethod for interpretation Categorize pHCategorize pH Determine Respiratory InvolvementDetermine Respiratory Involvement Determine Metabolic InvolvementDetermine Metabolic Involvement Assess for CompensationAssess for Compensation
InterpretationInterpretationA. Values
pH PCO2 HCO3 B.E. Respiratory Acidosis
1. Uncompensated - + N N 2. Partially Compensated - + + + 3. Compensated N + + +
Respiratory Alkalosis 4. Uncompensated + - N N 5. Partially Compensated + - - - 6. Compensated N - - -
Metabolic Acidosis 7. Uncompensated - N - - 8. Partially Compensated - - - - 9. Compensated N - - -
Metabolic Alkalosis 10. Uncompensated + N + + 11. Partially Compensated + + + + 12. Compensated N + + +
InterpretationInterpretation
StatesStates Respiratory AcidosisRespiratory Acidosis
CausesCauses CompensationCompensation CorrectionCorrection
Respiratory AlkalosisRespiratory Alkalosis CausesCauses Clinical SignsClinical Signs CompensationCompensation CorrectionCorrection Alveolar Hyperventilation Superimposed on Alveolar Hyperventilation Superimposed on
Compensated Respiratory AcidosisCompensated Respiratory Acidosis
InterpretationInterpretation
ValuesValuespHpH PCO2PCO2 HCO3HCO3 B.E. B.E.
Respiratory AcidosisRespiratory Acidosis Uncompensated Uncompensated -- ++ NN N N Partially CompensatedPartially Compensated -- ++ ++ ++ CompensatedCompensated NN ++ ++ ++
Respiratory AlkalosisRespiratory Alkalosis UncompensatedUncompensated ++ -- NN NN Partially CompensatedPartially Compensated ++ -- -- -- CompensatedCompensated NN -- -- --
Metabolic AcidosisMetabolic Acidosis UncompensatedUncompensated -- NN -- -- Partially CompensatedPartially Compensated -- -- -- -- CompensatedCompensated NN - - -- --
Metabolic AlkalosisMetabolic Alkalosis UncompensatedUncompensated ++ NN ++ ++ Partially CompensatedPartially Compensated ++ ++ ++ ++ CompensatedCompensated NN ++ ++ ++
InterpretationInterpretation
Metabolic AcidosisMetabolic Acidosis CausesCauses Anion GapAnion Gap CompensationCompensation SymptomsSymptoms CorrectionCorrection
Metabolic AlkalosisMetabolic Alkalosis Causes Causes CompensationCompensation CorrectionCorrection
Metabolic Acid-Base IndicatorsMetabolic Acid-Base Indicators Standard BicarbonateStandard Bicarbonate Base ExcessBase Excess
Assessment of HypoxemiaAssessment of Hypoxemia
On room air with normal Hb and under On room air with normal Hb and under 60 years old (PaO2 above 80mmHg = 60 years old (PaO2 above 80mmHg = no hypoxemia)no hypoxemia)
Normal = 80-100mmhgNormal = 80-100mmhg Mild hypoxemia = PaO2 = 60-79mmHgMild hypoxemia = PaO2 = 60-79mmHg Moderate hypoxemia = PaO2 = 40-Moderate hypoxemia = PaO2 = 40-
59mmHg59mmHg Severe hypoxemia PaO2 = less than Severe hypoxemia PaO2 = less than
40mmHg40mmHg
Assessment of HypoxemiaAssessment of Hypoxemia
O2 contentO2 content Mild hypoxemia 15-17 volume % (17)Mild hypoxemia 15-17 volume % (17) Moderate hypoxemia = 12-14 volume % (15)Moderate hypoxemia = 12-14 volume % (15) Severe hypoxemia = 12 volume % (12)Severe hypoxemia = 12 volume % (12)
Over 60 years oldOver 60 years old Subtract 1 mmHg for every year over 60Subtract 1 mmHg for every year over 60 Severe hypoxemia is still PaO2 <40mmHgSevere hypoxemia is still PaO2 <40mmHg
**Review Table 7-2 CARC p122 “Relationship between Age and Review Table 7-2 CARC p122 “Relationship between Age and Normal Predicted PaCO2Normal Predicted PaCO2
Assessment of HypoxemiaAssessment of Hypoxemia
Patients with abnormal HbPatients with abnormal Hb Calculate total O2 contentCalculate total O2 content
(Hb * 1.34 * SaO2) + (0. 003 * PaO2)(Hb * 1.34 * SaO2) + (0. 003 * PaO2) Mild hypoxemia = CaO2 17 volume %Mild hypoxemia = CaO2 17 volume % Moderate hypoxemia = CaO2 15 Moderate hypoxemia = CaO2 15
volume %volume % Severe hypoxemia = CaO2 12 volume Severe hypoxemia = CaO2 12 volume
%%
Other Oxygenation Other Oxygenation AssessmentsAssessments
Oxygen Saturation (SaO2)Oxygen Saturation (SaO2) Arterial Oxygen Content (CaO2)Arterial Oxygen Content (CaO2) Alveolar-Arterial Oxygen Difference [P(A-Alveolar-Arterial Oxygen Difference [P(A-
a)O2]a)O2] Partial Pressure of Oxygen in Mixed Partial Pressure of Oxygen in Mixed
Venous Blood (PvO2)Venous Blood (PvO2) Arteriovenous Oxygen Content Difference Arteriovenous Oxygen Content Difference
C(a-v)O2C(a-v)O2 Carboxyhemoglobin (HbCO)Carboxyhemoglobin (HbCO)
Assessment of Acid Base Assessment of Acid Base BalanceBalance
Hydrogen Ion Concentration (pH)Hydrogen Ion Concentration (pH) Partial Pressure of Arterial Carbon Partial Pressure of Arterial Carbon
Dioxide (PaCO2)Dioxide (PaCO2) Arterial Blood Bicarbonate (HCO3-)Arterial Blood Bicarbonate (HCO3-) Base Excess & Base DeficitBase Excess & Base Deficit
Control of Ventilation Control of Ventilation
VentilationVentilation Under control of autonomic or involuntary Under control of autonomic or involuntary
nervous systemnervous system Is controlled by central and peripheral Is controlled by central and peripheral
chemoreceptorschemoreceptors Central chemoreceptorsCentral chemoreceptors
Influenced by contents of the cerebrospinal Influenced by contents of the cerebrospinal fluid (CSF)fluid (CSF)
CO2 diffuses freely in CSFCO2 diffuses freely in CSF Increased CO2 in CSF will cause increased H+Increased CO2 in CSF will cause increased H+ Causes a stimulation of the inspiratory centerCauses a stimulation of the inspiratory center
Control of VentilationControl of Ventilation
Central chemoreceptors (cont)Central chemoreceptors (cont) Areas of the medullary centerAreas of the medullary center
Apneustic or pontine centerApneustic or pontine center Allows deep inspirationAllows deep inspiration
Pneumontaxic centerPneumontaxic center Limits inspiration from inspiration centerLimits inspiration from inspiration center Causes decreased rate of timeCauses decreased rate of time Hering-Breuer (stretch receptors)Hering-Breuer (stretch receptors)
Inflation reflex message carried to brain via Vagus Inflation reflex message carried to brain via Vagus nervenerve
Located in smooth muscle of both large and small Located in smooth muscle of both large and small airwaysairways
Limits inspirationLimits inspiration
Peripheral ChemoreceptorsPeripheral Chemoreceptors
Carotid bodiesCarotid bodies Responds to hypoxemiaResponds to hypoxemia Increases ventilationIncreases ventilation Located in the bifurcations of the common Located in the bifurcations of the common
carotid arteriescarotid arteries Aortic bodiesAortic bodies
Responds to hypoxemiaResponds to hypoxemia Usually effects heart more than ventilationUsually effects heart more than ventilation Located in the aortic archLocated in the aortic arch
Handle Gas Cylinders With Care
States of MatterStates of Matter
EnergyEnergy PotentialPotential KineticKinetic TemperatureTemperature
Absolute ZeroAbsolute Zero ScalesScales
Heat TransferHeat Transfer
States of MatterStates of Matter
FormsForms SolidSolid Liquid (Properties)Liquid (Properties)
PressurePressure BuoyancyBuoyancy ViscosityViscosity Cohesion & AdhesionCohesion & Adhesion Surface TensionSurface Tension Capillary ActionCapillary Action
GasGas
States of MatterStates of Matter
ChangesChanges Liquid to SolidLiquid to Solid
MeltingMelting FreezingFreezing
Liquid to Gas (Vapor)Liquid to Gas (Vapor) EvaporationEvaporation Vapor PressureVapor Pressure HumidityHumidity
Water Water How its behavior is different from other compounds How its behavior is different from other compounds
when it freezes or meltswhen it freezes or melts
GasesGases
Molecules continuously movingMolecules continuously moving Avogadro’s lawAvogadro’s law
1 gram atomic weight of any 1 gram atomic weight of any substance 6.02 * 10substance 6.02 * 102323 atoms atoms
This is known as 1 mole.This is known as 1 mole. 1 mole of a gas at STPD occupies 22.4 1 mole of a gas at STPD occupies 22.4
LL
PressurePressure
PB= barometric pressurePB= barometric pressure Normal barometric pressure isNormal barometric pressure is
760mmHg 760mmHg 14.7 PSI 14.7 PSI 1034cm H2O1034cm H2O 33ft of water33ft of water
Water vapor (or humidity) exerts Water vapor (or humidity) exerts pressurepressure
Partial pressure of H2O (PH2O) at 100% RH at Partial pressure of H2O (PH2O) at 100% RH at 37 degrees C = 47mmHg37 degrees C = 47mmHg
PressurePressure
Dalton's lawDalton's law The sum total of the individual partial The sum total of the individual partial
pressures of gases in the atmosphere pressures of gases in the atmosphere are equal to the barometric (PB = PN2 are equal to the barometric (PB = PN2 + PO2 +PTrace gases)+ PO2 +PTrace gases)
The pressure of each gas will be The pressure of each gas will be exerted when separated from a exerted when separated from a mixture (PN2 = PB * %N2)mixture (PN2 = PB * %N2)
Concentrations of Atmospheric Concentrations of Atmospheric GasesGases
Oxygen 20.95%Oxygen 20.95% Nitrogen 78.08%Nitrogen 78.08% Argon 0.93%Argon 0.93% Carbon Dioxide 0.03%Carbon Dioxide 0.03% Trace Gases 0.01 %Trace Gases 0.01 %
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
Partial pressure of a gas equals Pbar * Partial pressure of a gas equals Pbar * concentration (example: 760mmHg * 0.21 concentration (example: 760mmHg * 0.21 = 159mmHg for O2)= 159mmHg for O2)
In the lung the water vapor exerts a In the lung the water vapor exerts a pressure of 47mmHg thus it changes the pressure of 47mmHg thus it changes the pressure of the atmospheric gases in the pressure of the atmospheric gases in the alveoli (example: Pbar= 760mmHg – alveoli (example: Pbar= 760mmHg – 47mmHg = 713mmHg)47mmHg = 713mmHg)
Because of the change in the barometric Because of the change in the barometric pressure in the alveoli the partial pressure pressure in the alveoli the partial pressure of O2 also changes (example: PO2 = of O2 also changes (example: PO2 = 713mmHg * 0.21 = 149mmHg)713mmHg * 0.21 = 149mmHg)
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
In the lungs the CO2 is higher than in the In the lungs the CO2 is higher than in the atmosphere and affected by the atmosphere and affected by the respiratory quotient (the unequal respiratory quotient (the unequal exchange of O2 for CO2)exchange of O2 for CO2)
Example: 149mmHg – 50mmHg = Example: 149mmHg – 50mmHg = 99mmHg (99mmHg is alveolar partial 99mmHg (99mmHg is alveolar partial pressure of oxygen)pressure of oxygen)
8.0149 2PaCO
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
Ideal Alveolar Gas EquationIdeal Alveolar Gas Equation In addition to the effects of PH2O on partial In addition to the effects of PH2O on partial
pressure of gases in the alveoli, the carbon pressure of gases in the alveoli, the carbon dioxide diffusing from the bloodstream into dioxide diffusing from the bloodstream into the alveoli will further decrease alveolar PO2the alveoli will further decrease alveolar PO2
Since carbon dioxide is leaving the Since carbon dioxide is leaving the bloodstream, (a closed system), and entering bloodstream, (a closed system), and entering the respiratory tract, (an open system), there the respiratory tract, (an open system), there is an indirect relationship between the is an indirect relationship between the pressures of carbon dioxide and oxygenpressures of carbon dioxide and oxygen
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
Ideal Alveolar Gas Equation (cont)Ideal Alveolar Gas Equation (cont) Increases in PACO2 result in decreases Increases in PACO2 result in decreases
in PAO2in PAO2 This indirect relationship basically This indirect relationship basically
involves only carbon dioxide and involves only carbon dioxide and oxygen because they are the only oxygen because they are the only metabolically active gasesmetabolically active gases
Dalton's Law must be modified to Dalton's Law must be modified to account for incoming carbon dioxide account for incoming carbon dioxide when applied to alveolar when applied to alveolar
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
Ideal alveolar gas equationIdeal alveolar gas equation
PAO2 = FIO2 * (Pb - PH2O) - PCO2 / RQPAO2 = FIO2 * (Pb - PH2O) - PCO2 / RQ PAO2 = pressure of O2 in the alveoliPAO2 = pressure of O2 in the alveoli Pb = barometric pressurePb = barometric pressure PH2O = water pressurePH2O = water pressure FIO2 = fraction of inspired oxygenFIO2 = fraction of inspired oxygen PACO2 = pressure of CO2 in the alveoliPACO2 = pressure of CO2 in the alveoli RQ = respiratory quotientRQ = respiratory quotient
Application of Dalton's Law To Application of Dalton's Law To The LungThe Lung
A modification of the above equation A modification of the above equation maybe used with reasonably accurate maybe used with reasonably accurate resultsresults
PAO2 = (PB - PH2O)(FIO2) - PACO2PAO2 = (PB - PH2O)(FIO2) - PACO2 In both equations, PaCO2 is always In both equations, PaCO2 is always
considered equal to PACO2 because of considered equal to PACO2 because of the rapid equilibration of carbon the rapid equilibration of carbon dioxide (20 * faster or easier than O2)dioxide (20 * faster or easier than O2)
Gas LawsGas Laws
Ideal Gas LawIdeal Gas Law If mass is constant thenIf mass is constant then
2
22
1
11
T
VP
T
VP
Gas LawsGas Laws
Boyle's LawBoyle's Law If temperature and mass are constant If temperature and mass are constant
then volume and pressure are then volume and pressure are inversely proportionalinversely proportional
P1V1 = P2V2
Gas LawsGas Laws
Charles' LawCharles' Law If pressure and mass are constant then If pressure and mass are constant then
temperature and volume are directly temperature and volume are directly proportionalproportional
2
2
1
1
T
V
T
V
Gas LawsGas Laws
Gay-Lussac's LawGay-Lussac's Law If volume and mass remain constant, If volume and mass remain constant,
pressure and temperature are directly pressure and temperature are directly proportionalproportional
The triangle demonstrates the The triangle demonstrates the relationshiprelationship
2
2
1
1
T
P
T
P
Gas LawsGas Laws
All gas laws use temperature in All gas laws use temperature in Kelvin (absolute temperature scale)Kelvin (absolute temperature scale)
C + 273 = KelvinC + 273 = Kelvin
Relationships of Gas LawsRelationships of Gas Laws
Volume
Boyle’s Charles’m(constant)
Pressure TemperatureGay-Lussac’s
ExamplesExamples Ideal Gas EquationIdeal Gas Equation
A gas system has volume, moles, and temperature of A gas system has volume, moles, and temperature of 9160ml, 0.523 moles & 324K, respectively. What is the 9160ml, 0.523 moles & 324K, respectively. What is the pressure in torr?pressure in torr?P = xP = xV = 9160ml = 9.16LV = 9160ml = 9.16Ln = 0.523 molesn = 0.523 molesT = 324KT = 324K
(0.523 * 62.4 * 324) ÷ 9.16 = 1160 torr(0.523 * 62.4 * 324) ÷ 9.16 = 1160 torr How many moles of gas are contained in 890 ml at How many moles of gas are contained in 890 ml at
21°C and 750 mmHg pressure?21°C and 750 mmHg pressure?n = PV/RTn = PV/RT(750 mmHg ÷ 760mmHg atm-1)(0.89L) ÷ (0.08206L at (750 mmHg ÷ 760mmHg atm-1)(0.89L) ÷ (0.08206L at mol-1K-1)(294K)mol-1K-1)(294K)(0.9868) * (0.89) ÷ (24.12564)(0.9868) * (0.89) ÷ (24.12564)0.878252 ÷ 24.125640.878252 ÷ 24.12564n = 0.0364n = 0.0364
*Division of 750 by 760 is to convert mmHg to atm*Division of 750 by 760 is to convert mmHg to atm
ExamplesExamples
Boyle’s LawBoyle’s Law A gas system has initial pressure and volume A gas system has initial pressure and volume
of 3.69 atm and 5440ml. If the pressure of 3.69 atm and 5440ml. If the pressure changes to 2.38 atm, what will the resultant changes to 2.38 atm, what will the resultant volume be in ml?volume be in ml?
P1(V1) = P2 (V2)P1(V1) = P2 (V2)
3.69 * 5440 = 2.38x3.69 * 5440 = 2.38x
20073.6 = 2.38x20073.6 = 2.38x
x = 8434.29x = 8434.29
ExamplesExamples
Boyle’s Law (cont)Boyle’s Law (cont) A gas occupies 12.3L at a pressure of 40.0 A gas occupies 12.3L at a pressure of 40.0
mmHg. What is the volume when the mmHg. What is the volume when the pressure is increased to 60mmHg?pressure is increased to 60mmHg?40 * 12.3 = 60x40 * 12.3 = 60xx = 8.2Lx = 8.2L
If a gas at 25°C occupies 3.6L at a pressure If a gas at 25°C occupies 3.6L at a pressure of 1atm, what will be its volume at a pressure of 1atm, what will be its volume at a pressure of 2.5atm?of 2.5atm?1atm * 3.6L = 2.5x1atm * 3.6L = 2.5xx = 1.44Lx = 1.44L
ExamplesExamples
Charles’ LawCharles’ Law A gas system has an initial temperature A gas system has an initial temperature
of 308.9K with the volume unknown. of 308.9K with the volume unknown. When the temperature changes to -When the temperature changes to -230.4°C the volume is found to be 230.4°C the volume is found to be 1.67L. What was the initial volume in L?1.67L. What was the initial volume in L?
-230.4°C =>42.6K-230.4°C =>42.6K
11.12
863.5156.426.42
67.1
9.308
x
x
x
ExamplesExamples
Charles’ Law (cont)Charles’ Law (cont) Calculate the decrease in temperature Calculate the decrease in temperature
when 2L at 20°C is compressed to 1L.when 2L at 20°C is compressed to 1L.2L * 293 = 1x2L * 293 = 1xx = 146.5x = 146.5
A 600ml sample of nitrogen is warmed A 600ml sample of nitrogen is warmed from 77°C to 86°C. Find its new volume from 77°C to 86°C. Find its new volume if the pressure remains constant.if the pressure remains constant.600ml ÷ 350 = 359K 600ml ÷ 350 = 359K
ExamplesExamples
Guy-Lussac’s LawGuy-Lussac’s Law A container is initially at 47mmHg and 77K A container is initially at 47mmHg and 77K
(liquid nitrogen temperature). What will the (liquid nitrogen temperature). What will the pressure be when the container warms up to pressure be when the container warms up to room temperature of 25°C?room temperature of 25°C?Ans: 180mmHgAns: 180mmHg
A gas thermometer measures temperature by A gas thermometer measures temperature by measuring the pressure of a gas inside the measuring the pressure of a gas inside the fixed volume container. A thermometer reads a fixed volume container. A thermometer reads a pressure of 248 torr at 0°C. What is the pressure of 248 torr at 0°C. What is the temperature when the thermometer reads a temperature when the thermometer reads a pressure of 345 torr?pressure of 345 torr?Ans: 107Ans: 107°C°C
ExamplesExamples
Guy-Lussac’s Law (cont)Guy-Lussac’s Law (cont) A vessel has a pressure of 18.9 lb/in2 A vessel has a pressure of 18.9 lb/in2
at 20°C. What temperature is at 20°C. What temperature is necessary to lower the pressure to necessary to lower the pressure to 14.2 lb/in2?14.2 lb/in2?
Ans: -53°CAns: -53°C
Review Characteristics of Review Characteristics of Medical Gases Medical Gases
OxygenOxygen AirAir Carbon DioxideCarbon Dioxide HeliumHelium Nitrous OxideNitrous Oxide Nitric OxideNitric Oxide
Agencies Regulating Gas Agencies Regulating Gas AdministrationAdministration
DOT - Department of TransportationDOT - Department of Transportation Before 1970, was called ICC – Interstate CommissionBefore 1970, was called ICC – Interstate Commission Regulates construction, transport and testing of Regulates construction, transport and testing of
cylinderscylinders HHS - Department. of Health & Human ServicesHHS - Department. of Health & Human Services
Formerly called HEW - Department. of Health, Formerly called HEW - Department. of Health, Education and WelfareEducation and Welfare
FDA - Food & Drug Administration - is part of HHS - FDA - Food & Drug Administration - is part of HHS - regulates the purity of gases regulates the purity of gases
OSHA Occupational Safety & Health OSHA Occupational Safety & Health Administration - responsible for occupational Administration - responsible for occupational safetysafety
Recommending BodiesRecommending Bodies
CGA - Compressed Gas Association - created CGA - Compressed Gas Association - created safety systemssafety systems
NFPA - National Fire Protection Assn.NFPA - National Fire Protection Assn. Fire preventionFire prevention Governs storageGoverns storage
Z-79 – Committee of American National Z-79 – Committee of American National Standards for Anesthetic Equipment, which Standards for Anesthetic Equipment, which includesincludes
Ventilator devicesVentilator devices Reservoir bagsReservoir bags Trachea tubes and their connectorsTrachea tubes and their connectors HumidifiersHumidifiers Other related equipmentOther related equipment
Safety Systems for Safety Systems for CylindersCylinders
Color coding for E cylinders (not Color coding for E cylinders (not mandatory for larger cylinders)mandatory for larger cylinders)
Oxygen – green (white internationally)Oxygen – green (white internationally) Carbon dioxide – greyCarbon dioxide – grey Nitrous oxide – blueNitrous oxide – blue Cyclopropane – orangeCyclopropane – orange Helium – brownHelium – brown Ethylene – redEthylene – red Air – yellowAir – yellow Nitrogen – blackNitrogen – black
Safety Systems for Safety Systems for CylindersCylinders
Pin Index Safety SystemPin Index Safety System E cylinders and smallerE cylinders and smaller High pressure (greater than 200psi)High pressure (greater than 200psi) Yoke & pin connectionsYoke & pin connections Oxygen 2-5 positionOxygen 2-5 position Air 1-5 positionAir 1-5 position CO2 1-6 positionCO2 1-6 position
Safety Systems for Safety Systems for CylindersCylinders
American Standard Safety SystemAmerican Standard Safety System Larger than E cylindersLarger than E cylinders High pressureHigh pressure Nipple & threaded nutNipple & threaded nut
Safety Systems for Safety Systems for CylindersCylinders
Diameter Index Safety SystemDiameter Index Safety System Low pressures (less than 200 PSI)Low pressures (less than 200 PSI) All connections after the regulatorAll connections after the regulator Threaded nut & nippleThreaded nut & nipple
Qualities of cylinder gasesQualities of cylinder gases
Flammable Gases Flammable Gases EthyleneEthylene CyclopropaneCyclopropane
Nonflammable GasesNonflammable Gases NitrogenNitrogen Carbon dioxideCarbon dioxide HeliumHelium
Qualities of cylinder gasesQualities of cylinder gases
Gases that support combustionGases that support combustion OxygenOxygen Oxygen mixturesOxygen mixtures
Helium/oxygen – helioxHelium/oxygen – heliox Oxygen/carbon dioxide – carbogenOxygen/carbon dioxide – carbogen Oxygen/nitrogenOxygen/nitrogen Oxygen/nitrous oxideOxygen/nitrous oxide
Nitrous oxideNitrous oxide
Qualities of oxygenQualities of oxygen
ColorlessColorless OdorlessOdorless TastelessTasteless Atomic weight = 16gmsAtomic weight = 16gms Molecular weight = 32gmsMolecular weight = 32gms Critical temperatureCritical temperature -118.8ºC or -181.1ºF at 49.7 atm-118.8ºC or -181.1ºF at 49.7 atm Above this temperature it cannot remain a Above this temperature it cannot remain a
liquidliquid Fractional distillationFractional distillation
Cylinder marking and Cylinder marking and testingtesting
FrontFront DOT-3AA 2015 PSI– these are DOT DOT-3AA 2015 PSI– these are DOT
specifications and service pressurespecifications and service pressure Serial numberSerial number Ownership markingsOwnership markings Manufacturers markManufacturers mark
Cylinder marking and Cylinder marking and testingtesting
BackBack Original hydrostatic testingOriginal hydrostatic testing SpecificationsSpecifications Retest datesRetest dates Inspectors mark and specificationsInspectors mark and specifications
Cylinders are filled to 5/3 maximum Cylinders are filled to 5/3 maximum pressure every 5-10 years pressure every 5-10 years (hydrostatic testing)(hydrostatic testing)
Cylinder Filling and DurationCylinder Filling and Duration
Can be overfilled by 10% to hold Can be overfilled by 10% to hold 2200 PSI2200 PSI
Duration of flow in minutes =Duration of flow in minutes =
flowliter
factorTankpressureTank
Cylinder Filling and DurationCylinder Filling and Duration
Tank factors for O2 duration of flowTank factors for O2 duration of flow E = 0.28E = 0.28 G = 2.41G = 2.41 H = 3.14H = 3.14
These factors are used to calculate absolute These factors are used to calculate absolute duration times; however, in practice a safety factor duration times; however, in practice a safety factor must be utilized to insure no interruptions in gas must be utilized to insure no interruptions in gas therapy to the patienttherapy to the patient
Cylinder capacitiesCylinder capacities E = 22 ft3 or 616 liters @ 2200 psig E = 22 ft3 or 616 liters @ 2200 psig G = 187 ft3 or 5308 liters @ 2200 psig G = 187 ft3 or 5308 liters @ 2200 psig H = 244 ft3 or 6908 liters @ 2200 psigH = 244 ft3 or 6908 liters @ 2200 psig
Cylinder HandlingCylinder Handling
Keep in carrier or standKeep in carrier or stand No flames/smokingNo flames/smoking Proper technique in attaching regulatorsProper technique in attaching regulators
Remove capRemove cap Turn on gas momentarily (away from people) Turn on gas momentarily (away from people)
“cracking”“cracking” Place and tighten regulatorPlace and tighten regulator Turn on gasTurn on gas Adjust flowAdjust flow Bleed off pressure when not in useBleed off pressure when not in use
Cylinder HandlingCylinder Handling
Store with cap on to prevent Store with cap on to prevent breaking stembreaking stem
Cylinder testingCylinder testing Every 5- 10 yearsEvery 5- 10 years Water displacement measured to Water displacement measured to
check for expansion with 5/3 maximum check for expansion with 5/3 maximum pressurepressure
Gaseous bulk systems three Gaseous bulk systems three general typesgeneral types
StandardStandard Large H or K size cylinders banked into a Large H or K size cylinders banked into a
manifold systemmanifold system Primary bankPrimary bank Reserve bank (automatically switches to this Reserve bank (automatically switches to this
when primary system drops to a preset lower when primary system drops to a preset lower pressure limitpressure limit
Six or more cylinders manifolded together. Six or more cylinders manifolded together. Alarms are activated when reserve switches Alarms are activated when reserve switches on or malfunction occur. Cylinders are on or malfunction occur. Cylinders are replaced as needed.replaced as needed.
Gaseous bulk systems three Gaseous bulk systems three general typesgeneral types
Fixed cylindersFixed cylinders Large bank of permanently fixed cylinders Large bank of permanently fixed cylinders
(up to 75)(up to 75) Refilled on site by a liquid O2 truck that Refilled on site by a liquid O2 truck that
converts the liquid into gas to fill tanksconverts the liquid into gas to fill tanks Trailer units (2200 PSI)Trailer units (2200 PSI)
Very large cylinders mounted on trailers Very large cylinders mounted on trailers towed to a central location for connectiontowed to a central location for connection
When low or in need of maintenance replaced When low or in need of maintenance replaced with fresh trailerwith fresh trailer
Gaseous bulk systems three Gaseous bulk systems three general typesgeneral types
Liquid Oxygen SystemsLiquid Oxygen Systems Liquid O2 is stored at -183°C or -297°F in thermos Liquid O2 is stored at -183°C or -297°F in thermos
bottle type storage vessels (inner and outer steel bottle type storage vessels (inner and outer steel shells separated by a vacuum)shells separated by a vacuum)
Pressure readings do not indicate remainder of O2 Pressure readings do not indicate remainder of O2 because the liquid O2 doesn't exert gas pressurebecause the liquid O2 doesn't exert gas pressure
Weight will indicate remainder of O2Weight will indicate remainder of O2 Pressures not to exceed 250 PSI in containers in LOX Pressures not to exceed 250 PSI in containers in LOX
containerscontainers Specifications for bulk systems by NFPASpecifications for bulk systems by NFPA Piping systemsPiping systems
Locate zone valves in hospitalLocate zone valves in hospital Do not turn off unless directed by fire chiefDo not turn off unless directed by fire chief
Gaseous bulk systems three Gaseous bulk systems three general typesgeneral types
Liquid Oxygen Systems (cont)Liquid Oxygen Systems (cont) Most economicalMost economical
1 ft3 of liquid O2 = 860 ft3 of gaseous O2 @ 1 ft3 of liquid O2 = 860 ft3 of gaseous O2 @ ambient temperatureambient temperature
Liquid O2 cylinders are used when usage too large Liquid O2 cylinders are used when usage too large for and not large enough for a permanently liquid for and not large enough for a permanently liquid vessel (come in various sizes see textbook)vessel (come in various sizes see textbook)
Fixed station (stand tanks) are large spherical with Fixed station (stand tanks) are large spherical with gaseous equivalents up to 130,000 cubic feet. gaseous equivalents up to 130,000 cubic feet. Refilled by service tank trucks.Refilled by service tank trucks.
All liquid O2 tank containers are equipped with 50 All liquid O2 tank containers are equipped with 50 PSI reducing valves.PSI reducing valves.
Liquid O2 duration (in minutes)Liquid O2 duration (in minutes)Pounds of liquid O2 * 344 =Pounds of liquid O2 * 344 =Liters per minuteLiters per minute
Gaseous bulk systems three Gaseous bulk systems three general typesgeneral types
Safety precautions for bulk O2Safety precautions for bulk O2 Must have 24 hour reserve or back-up supplyMust have 24 hour reserve or back-up supply Procedure for total system failure should be knownProcedure for total system failure should be known
Oxygen ConcentratorsOxygen Concentrators MembraneMembrane
Thin membrane-1 µm thickThin membrane-1 µm thick Oxygen and H2O pass through membrane faster than Oxygen and H2O pass through membrane faster than
nitrogennitrogen Delivers an FIO2 of about 40%Delivers an FIO2 of about 40%
Molecular SieveMolecular Sieve Uses a sieve filled with sodium-aluminum silicateUses a sieve filled with sodium-aluminum silicate Air is forced through the sieveAir is forced through the sieve The nitrogen is scrubbed from the airThe nitrogen is scrubbed from the air Delivers an FIO2 of about 90% at 2 LPMDelivers an FIO2 of about 90% at 2 LPM At higher flows the FIO2 decreasesAt higher flows the FIO2 decreases
RegulatorsRegulators
Reduce high tank pressure to low Reduce high tank pressure to low working pressureworking pressure
Usually 50 PSIUsually 50 PSI Single stage regulatorSingle stage regulator
Reduces tank pressure to 50 PSI in 1 Reduces tank pressure to 50 PSI in 1 stepstep
Has one pressure relief valve (about Has one pressure relief valve (about 200 PSI)200 PSI)
RegulatorsRegulators
Multi-stage regulatorMulti-stage regulator Reduces tank pressure to working pressure in Reduces tank pressure to working pressure in
2 or more steps2 or more steps Each stage has a pressure relief valveEach stage has a pressure relief valve The more stages the less fluctuation of The more stages the less fluctuation of
working pressureworking pressure Preset regulatorPreset regulator
Single or multi-stage regulator that is set to Single or multi-stage regulator that is set to have pressure reduced to set working have pressure reduced to set working pressure (usually 50 PSI)pressure (usually 50 PSI)
Has no way to adjust working pressureHas no way to adjust working pressure
RegulatorsRegulators
Adjustable regulatorAdjustable regulator Single or multi-stage regulator in which Single or multi-stage regulator in which
working pressure may be set variablyworking pressure may be set variably
FlowmetersFlowmeters
Control and indicate flowControl and indicate flow Thorpe TubeThorpe Tube
Vertical funnel shape tube with floatVertical funnel shape tube with float Must be kept vertical to be accurateMust be kept vertical to be accurate
FlowmetersFlowmeters
Compensated Thorpe Tube FlowmeterCompensated Thorpe Tube Flowmeter Needle valve adjustment is distal (after Needle valve adjustment is distal (after
or downstream) to the floator downstream) to the float Indicated flow is accurate in the presence Indicated flow is accurate in the presence
of back pressure to check for of back pressure to check for compensation:compensation:
Label calibrated at 70ºF, 50 PSILabel calibrated at 70ºF, 50 PSI Visualize needle valve placementVisualize needle valve placement Turn unit off and plug into pressureTurn unit off and plug into pressure Float will rise, then fallFloat will rise, then fall
FlowmetersFlowmeters
Uncompensated Thorpe Tube Uncompensated Thorpe Tube FlowmeterFlowmeter
Needle is proximal (upstream or Needle is proximal (upstream or before) the floatbefore) the float
Flow meter reading will be lower than Flow meter reading will be lower than what is delivered to the patient if back what is delivered to the patient if back pressure is presentpressure is present
FlowmetersFlowmeters
Kinetic FlowmeterKinetic Flowmeter Has plunger instead of floatHas plunger instead of float All other areas of Thorpe tubes applyAll other areas of Thorpe tubes apply
FlowmetersFlowmeters
FlowmetersFlowmeters
Bourdon GaugeBourdon Gauge Measures pressure but reads flowMeasures pressure but reads flow Flow delivered to patient is less than Flow delivered to patient is less than
flow shown on the gauge if back flow shown on the gauge if back pressure is present pressure is present
Works in any positionWorks in any position
FlowmetersFlowmeters
Use of oxygen flowmeters with Use of oxygen flowmeters with heliumhelium
Due to density of gases flow will not be Due to density of gases flow will not be accurateaccurate
80% helium, 20% O2 flow will be 1.8 80% helium, 20% O2 flow will be 1.8 times the meter readingtimes the meter reading
70% helium, 30% O2 flow will be 1.6 70% helium, 30% O2 flow will be 1.6 times the meter readingtimes the meter reading
CompressorsCompressors
PistonPiston DiaphragmDiaphragm CentrifugalCentrifugal Assembly & Troubleshooting (White Assembly & Troubleshooting (White
p15)p15)
ValvesValves
Direct ActingDirect Acting DiaphragmDiaphragm Safety FeaturesSafety Features ReducingReducing
Single stageSingle stage Modified Single stageModified Single stage MultistageMultistage Safety FeaturesSafety Features
RegulatorsRegulators
ConservationConservation
List current manufacturer and List current manufacturer and modelmodel
Describe how each acts as a Describe how each acts as a conservation optionconservation option
BlendersBlenders
See textbookSee textbook