\


QuestionAnswer
Amount of O2 dissolved in each ml of plasmaFor every 760 mmHg pressure, .023 ml of O2 dissolves in each ml of plasma
Calculation of O2 dissolved in bloodPO2 x .003
How many Hb molecules are in each RBC?280 million
How many heme groups and amino acid chains are in normal Hb?4 heme groups, 4 amino acid chains
When can Hb be said to be 100% saturated with O2?When 4 O2 molecules are bound to 1 Hb molecule
When hb is bound with 3 O2 molecules it is ___% saturated.75%
Hb bound with O2oxyhemoglobin
Hb not bound with O2deoxyhemoglobin
Amt. of Hb bound to O2 is directly related toPP of O2
Normal Hb for male14-16g/100 ml of blood (g%)
Normal Hb for female12-15g%
Each g% is capable of carrying about ___ ml of O21.34
At normal PaO2 of 100, what is the saturation and why?Sat is 97% because of normal physiologic shunting
Oxyhemoglobin dissociation curvesigmoid curve that results at O2 tensions between 0-150 mmHg, shows the relationship between PO2 and Hb at the lungs and at the tissues
Sigmoidal curve indicatesHb’s affinity for O2 provides 97% saturation at the normal arterial tension of 100 mmHg, and a 75% saturation at the normal mixed venous tension of 40 mmHg
Right shiftP50 value > 27, indicates decreased affinity
Left ShiftP50 value < 27, indicates increased affinity
P50Normal Hb is 50% saturated with the O2 at a PaO2 of 27 mmHg
PO2 60-100Still 90% saturated
What promotes the pickup and delivery of O2?PCO2, pH, and temperature
Clinical signs of hypoxiaTachycardia, hyperventilation, restlessness, hypertension (early), hypotension (late), confusion and disorientation, possible cyanosis, lactic acidosis, polycythemia
Hypoxemic hypoxiaDecreased alveolar ventilation, decreased inspired oxygen tension, ventilation to perfusion mismatch, diffusion defect
Anemic hypoxiaCarbon monoxide poisoning, abnormal Hb–methemoglobinemia, low Hb, sickle cell
Circulatory hypoxiaBradycardia, hypotension, low cardiac output, cardiac arrest
Histotoxic hypoxiaInability to accept and use O2 as seen in cyanide poisoning
The only hypoxia where a patient will always also be hypoxemic is:Hypoxemic hypoxia–PaO2 can be normal in other types
CyanosisGenerally more than 5gm% of reduced Hb results in cyanosis
QuestionAnswer
Hypoxic HypoxiaLow PaO2
Anemic HypoxiaDecreased Hb or O2 carrying capacity of Hb.
Circulatory Hypoxia – CardiacInsufficent pulmonary blood flow
Circulatory Hypoxia – StagnantDecrease or absent blood flow to tissue cells. Also, arterial-venous shunting: Blood bypasses tissue cells.
PolycythemiaIncreased amount of RBC’s in response to chronic hypoxemia. Resulting blood viscosity increase (thick blood)offsets some beneficial effects by increasing myocardial work.
CyanosisA blueish discoloration of the skin or mucosa caused by hypoxemia. Technical definition > 5 gm% of reduced Hb.
Digital ClubbingChronic Pulmonary Osteoarthropathy – Diagnosis made by dissapearance of normal finger/nailbed angle.
Arterial Blood Gas (ABG)Measurement of the gases in the arterial blood which is on it’s way back from the lungs going to the various body parts & tissues.
Arterial Blood Gas (ABG)Lower in CO2 and higher in O2.
Arterial Blood Gas (ABG)Tells how good a job the lungs are doing removing CO2 and providing O2.
Normal Arterial Blood Gas Value – pH7.35 – 7.45
Normal Arterial Blood Gas Value – PCO235-45 mmHg (PaCO2)
Normal Arterial Blood Gas Value – HCO322-28 mEq/L
Normal Arterial Blood Gas Value – PO280-100 mmHg (PaO2)
Normal Arterial Blood Gas Value – BE+/- 2.0
Blood Gas AnalyzerAnalyzes pH, PCO2, PO2, BE, & SaO2 estimated.
Co-OximeterAnalyzes Hb, COHb, MetHb & SaO2 measured.
Oxygent Content Calculation (CaO2)(gm%Hgb x 1.34) x SaO2 + (.003 x PaO2)
O2 may be dissolved in plasma. When carried this way, it exerts a partial pressure and is expressed as:PaO2
What is the more commonly used lab value?PaO2
What lab value is more meaningful and a better assesment of the patients oxygentation status?SaO2
Where do you get the PaO2 value from?ABG
Where do you get the SaO2 value from?Co-Oximetry
Oxyhemoglobin Dissociation CurveIllustrates the % of hemoglobin that is chemically bound to oxygen at each oxygen pressure.
ShuntCardiac output that reaches left heart without having exchanged gases in the alveoli.
True/Absolute Shunt – AnatomicBlood flow from the right to the left heart without perfusing alveoli.
True/Absolute Shunt – CapillaryPerfusion of unventilated alveoli.
Shunt-Like EffectCaused by impaired ventilation and/or perfusion.
Venous AdmixtureEnd result of pulmonary shunting.
Oxygen Dissociation Curve(or Oxygen–Hemoglobin Dissociation Curve) Plots the proportion of hemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis.
CaO2 =(gm% Hgb x 1.34) x SaO2 + (0.003 x Pa02)
How is most of our oxygen carried?Bound to Hemoglobin
Abnormal Hemoglobin – Deoxygenated/ReducedHemoglobin that has reduced or no oxygen
Abnormal Hemoglobin – FetalFetal & Newborn Hemoglobin
Abnormal Hemoglobin – CarboxyhemoglobinCarbon Monoxide & Hemoglobin
Abnormal Hemoglobin – MethemoglobinMet Molecule & Hemoglobin
Bohr EffectStates that an increasing concentration of protons and/or carbon dioxide will reduce the oxygen affinity of hemoglobin.
A-aDO2{(PB – PHO2) x FiO2} – PaCO2 x 1.25

QuestionAnswer
HypoxemiaAn abnormal low arterial oxygen tension (PaO2) and frequently associated with Hypoxia.
HypoxiaAn inadequate level of tissue oxygenation. Inadequate oxygen for cellular metabolism.
If pt is hypoxic, do they have hypoxia?Not always! It strongly suggests it but in mild hypoxic pts hypoxia does not necessarily exist.
Hypoxic Hypoxia (aka Hypoxemic Hypoxia)The condition in which there is inadequate oxygen at the tissue cells caused by low arterial oxygen tension (PaO2).
Hypoxic Hypoxia common causes are:-Hypoventilation -high altitude -Diffusion defects, i.e. interstitial fibrosis or lung disease, pulmonary edema, pneumoconiosis, -V/Q mismatch, -Pulmonary shunting.
Anemic HypoxiaPaO2 is normal but the oxygen-carrying capacity of the hemoglobin is inadequate.
Anemic Hypoxia common causes are:-Decreased hemoglobin, i.e. anemia or hemorrhage, -Abnormal hemoglobin, i.e. carboxyhemoglobinemia or methemoglobinemia.
Carbon monoxide has an affinity to hemoglobin _____ times greater than that of oxygen.210
MethemoglobinemiaIron atoms (Fe2+) are oxidized to ferric (Fe3+) and can no longer carry oxygen in hemoglobin. This suffocates the tissue.
What is the main compensatory mechanism of anemic hypoxia?Increased cardiac output.
Circulatory Hypoxia (aka Stagnant or Hypoperfusion Hypoxia)May have normal oxygen tension but blood flow to the tissue cells is inadaquate; thus, oxygen is not adequate to meet tissue needs.
Circulatory Hypoxia common causes are:-Slow or stagnant (pooling) peripheral blood flow, -arterial-venous shunts.
Histotoxic HypoxiaImpaired ability to the tissue cells to utilize oxygen.
Histotoxic Hypoxia common cause is:Cyanide poisoning; develops in any condition that impairs the ability of tissue cells to utilize oxygen.
Hypoventilation common causes are:COPD, central nervous system depressants, head trauma, and neuromuscular disorders (i.e. myasthenia gravis or Gullain-Barre syndrome).
Diffusion Defects are what?Abnormal anatomic alterations of the lungs that result in an impedance of oxygen transfer across the alveolar-capillary membrane. Causes reduced time for oxygen equilibrium between the alveolus and pulmonary capillary.
Diffusion Defects common causes are:Chronic interstitial lung diseases, pulmonary edema, and pneumoconiosis.
Ventilation-Perfusion Mismatch is what?When the pulmonary capillary blood is in excess of the alveolar ventilation. Causes pulmonary shunting which causes < PaO2 & CaO2
Ventilation-Perfusion Mismatch common causes are:COPD, pheumonia, and pulmonary edema.
Pulmonary shunting causes what?Decreased PaO2 & CaO2.
When the oxygen tension in the arterial blood is normal but the oxygen-carrying capacity of the blood is inadaquate, what condition is this?Anemic Hypoxia
Stagnant Hypoxia (aka Hypoperfusion)Occurs when the peripheral capillary blood flow is slow or stagnant.
Stagnant Hypoxia common causes are:-Decreased cardiac output, -vascular insufficiency, -neurochemical abnormalities, -Primarily assoc with cardiovascular disorders.
Stagnant Hypoxia causes what?Sluggish blood which increases the time needed for oxygen exchange but at the same time is supplying less oxygen. The oxygen pressure gradient between the blood & tissues cells decreases causing tissue hypoxia.
Arterial-venous shunt is what?When arterial blood completely bypasses the tissue cells and moves into the venous system.
CyanosisSevere hypoxemia. Term used to describe the blue-gray or purplish discoloration seen on the mucous membranes, fingertips, and toes whenever blood in these areas contains at least 5 g% of reduced hemoglobin per dL (100 mL).
Polycythemia means what?An increase in RBC’s, increases the oxygen-carrying capacity of blood.
When pulmonary disorders produce chronic hypoxemia what is stimulated?The hormone erythropoietin stimulates the bone marrow to increase RBC production, which is called erythropoiesis.
Polycythemia causes what?Increased viscosity needing a greater driving pressure to maintain flow, which increases the work of the R & L ventricles. Can lead to L ventricular hypertrophy and failure and to R ventricular hypertrophy, and cor pulmonale.
Oxygen is carried in the blood in two forms,1. dissolved oxygen in the blood plasma, and 2. chemically bound to hemoglobin that is encased in the RBC’s.
Dissolve means,that when a gas like oxygen enters the plasma, it maintains its precise molecular structure and moves freely throughout the plasma in its normal gaseous state. This is the portion of O2 that is measured to assess pt PO2. (0.003 mL dissolved O2 factor).
The quantity of O2 that dissolves in the plasma is a function of what?Henry’s Law = the amount of gas that dissolves in a liquid at a given temp is proportional to the partial pressure of gas.
Vol% represents what?The amount of O2 in mL that is in 100 mL of blood. Vol% = mL O2/100 mL blood.
RBC contains approximately ______ million hemoglobin molecules.280
Normal adult hemoglobin consists of what?4 heme groups, which are the pigmented, iron-containing non-protein portions of the hemoglobin molecule, and 4 amino acid chains (polypeptide chains) that collectively constitue globin (a protein).
Hb + O2 <—–>HbO2 (oxyhemoglobin)
Four heme/iron groups in each Hb molecule =Four O2 molecules that combine w/each Hb molecule.
When 4 O2 are combined w/one Hb molecule it is said to be ______% saturated.100
Hb not bound to O2 is called what?Reduced hemoglobin or deoxyhemoglobin.
The amount of O2 bound to Hb is ______ related to the partial pressure of O2.Directly.
Globin portion of each Hb molecule consists of what?2 identical alpha chains, each with 141 amino acids, and 2 identical beta chains, each with 146 amino acids.
Normal hemoglobin values:Adult male – 14 – 16 g/100 mL of blood (g%) Adult female – 12 – 15 g% Infant – 14 – 20 g%
g% =gram percent of hemoglobin
g/dLgrams per deciliter
Quantity of O2 bound to Hbvol% O2 = 1.34 mL O2 x Yg% (.97 or SaO2)
Hb saturation is only about 97% because of what normal physiologic shunts?1. Thebesian venous drainage into the left atrium, 2. bronchial venous drainage into the pulmonary veins, and 3. alveoli that are underventilated relative to pulmonary blood flow.
Dissolved O2 + O2 bound to Hb =Total amount of O2 in 100 mL of blood
Dissolved O2YmmHg x 0.003
O2 bound to HbYg% x 1.34 (SaO2)
CaO2 (O2 content of arterial blood) =(Hb x 1.34 x SaO2) + (PaO2 x 0.003)
CVO2 (O2 content of mixed venous blood) =(Hb x 1.34 x SVO2) + (PVO2 x 0.003)
CCO2 (O2 content of pulmonary capillary blood)(Hb x 1.34) + (PAO2 x 0.003)
The total amount of O2 delivered or transported to the peripheral tissues is dependent on,1. the body’s ability to oxygenate blood, 2. the hemoglobin concentration, and 3. the cardiac output.
Total oxygen delivery (DO2) (tells what is available to the cells) =Qt (total cardiac output, L/min) x (CaO2 x 10) — multiply by 10 to convert CaO2 from mL to L.
CvO2 tells,how much O2 has been consumed by the cells. Average is 15 vol%.
Oxygen delivery decreases when there is a decline in,1. blood oxygenation, 2. hemoglobin concentration, or 3. cardiac output.
An individual’s hemoglobin concentration or cardiac output will often ______ in an effort to compensate for a reduced oxygen delivery.Increase
Arterial-venous oxygen content difference =C(a – V)O2 or CaO2 – CVO2 — CVO2 obtained from pt pulmonary artery.
CaO2 – CVO2 norms =20 vol% – 15 vol% = 5 vol% (arterial-venous diff)
O2 Consumption =O2 used in 1min time. Amount of O2 extracted by the periperal tissues during 1min.
O2 Consumption Calculation =VO2 = Qt [C(a-V)O2 x 10]
Average cardiac output (Qt)5 L/min
Factors that increase C(a-V)O2– decreased cardiac output, – periods of increased O2 consumption, i.e. exercise, seizures, shivering, hyperthermia
Factors that decrease C(a-V)O2– Increased cardiac output, – skeletal muscle relaxation (by drugs), – peripheral shunting, – certain poisons, – hypothermia
Oxygen consumption is usually related to the pt ______?BSA – Body Surface Area — found on a chart, we cannot calculate.
Normal BSA125 – 165 mLO2/m squared
Pt O2 consumption index is derived by what?VO2/BSA
Factors that increase VO2– exercise, – seizures, – shivering, – hyperthermia
Factors that decrease VO2– skeletal muscle relaxation (drugs), – peripheral shunting, – certain poisons, – hypothermia
Oxygen concentration ratio (O2ER)the amount of O2 extracted by the peripheral tissues divided by the amount of O2 delivered to the peripheral cells. Aka oxygen coefficient ratio or oxygen utilization ratio.
O2ER calculationC(a – V)O2/CaO2
Normally, a pts Hb returns to the alveoli approximately _____% saturated with O2.75
Factors that increase O2ER– dec cardiac output, – periods of inc O2 consumption, i.e. exercise, seizures, shivering, hyperthermia, – anemia, – dec arterial oxygenation.
Factors that decrease O2ER– inc cardiac output, – skeletal muscle relaxation (drugs), – peripheral shunting, – certain poisons, – hypothermia, – inc Hb concentration, – inc arterial oxygenation.
Mixed venous oxygen saturation (SVO2)Continuous monitoring of SVO2 is often used to detect changes in the pts C(a-V)O2, VO2, and O2ER. Norm is 75%, about 65% is acceptable.
Factors that decrease SVO2– dec cardiac output, – periods of inc oxygen cunsumption, i.e. exercise, seizures, shivering, hyperthermia.
Factors that increase SVO2– inc cardiac output, – skeletal muscle relaxation (drugs), – peripheral shunting, – certain poisons, – hypothermia.
Shuntperfusion without ventilation
Pulmonary ShuntingThat portion of the cardiac output that moves from the right side to the left side of the heart without being exposed to alveolar oxygen (PAO2). Divided by 1. absolute (true) shunts and 2. relative shunt (aka shunt-like effects).
Absolute ShuntDoes NOT respond to O2 therapy because there is no gas exchange. Divided by 1. anatomic shunts and 2. capillary shunts.
QuestionAnswer
Low flow systemsDo not meet the patients inspiratory flow demands.,Normal inspiratory flow rate is 25 to 30 L/min,Additional flow comes from RA
Low flow systems includeNasal Cannula,Nasal,Catheters,Transtracheal Catheters, Simple masks, Partial Rebreathing Masks, Non-rebreathing Mask
High Flow Oxygen Systems IncludeVenturi Mask or air-entrainment masks,Aerosol Mask, Face Tent, T-Piece, Trach Mask, Oxygen Tent
Nasal Cannula and Nasal CathetersDelivers 24 to 44% oxygen at 1 to 6 L/min 1 = 24, 2 = 28, 3 = 32, 4 = 36, 5 = 40, 6 = 44
Nasal Catheters positionmeasured from nose to ear, lubricated, inserted to just above the uvula
Nasal Catheters consdeep insertion can cause air swallowing and gastric distension , must be repositioned every 8 hours to prevent breakdown
Transtracheal CathetersDelivers low flow rates (1 to 3 L/min) directly to the trachea through a small incision, Requires less oxygen (lower flows) because the upper airway deadspace is bypassed
Transtracheal Catheters riskCan develop infection and irritation at site and there is a risk of accidental removal, If pt becomes SOB or has increased, Flush with saline, Cleaning Rod, reposition
Cannulasbetter tolerated, may be humidified but often not if run @ less than 5 L/min, there are two types of O2-conserving cannulas 
Nasal reservoirreservoir just below the nose stores ~ 20 mL of O2 ,allows for lower flows because of increase O2 delivery
Pendent reservoirpendent stores O2 ,must exhale through nose
Pendent reservoir limitsHFNC – 6-15lpm
Simple masksDelivers 35 to 55 % O2 at flows of 5 to 12 L/min
Partial Rebreathing MasksDelivers 35 to 60 % O2 at flow rates of 8 to 15 L/min
Partial Rebreathing Masks ConsFlow rate must be sufficient to keep bag 1/3 to 1/2 inflated at all times
Non-rebreathing MaskFlow rate must be sufficient to keep bag 1/3 to 1/2 inflated at all times ,Is equipped with a one-way valve that does not allow exhaled gas into the reservoir, One way valves are located on both expiratory ports of the mask to prevent RA entrainment 
Methods for setting up high flow oxygenair entrainment mask, mechanical aerosol systems, Gas Injection Nebulizer- need high flow flowmeters, High FiO2 Misty Ox- for FiO2 of .60+ , Blender and titration system
High flow O2 systems provideall of the inspiratory flow required by the patient at consistent FiO2s, These devices are normally attached to nebulizers (Venti-mask may or may not be)
Venturi Mask or air-entrainment masksprovide FiO2’s from 24 to 50%
what happens with Venturi Mask or air-entrainment masksIncreasing flow will not alter FiO2 (precise) The size of the entrainment port determines FiO2 The larger the port, the more RA entrained, the lower the FiO2
Aerosol MaskDelivers 21-100% FiO2 depending on nebulizer setting, Flow rates of 8 to 15 L/min 
Aerosol Mask limitsOn 100% the device will probably not meet flow demands.(>60%) (No air entrained so flow = flowmeter setting)
Face Tent21% to 40% depending on nebulizer setting Flow rates of 8 to 15 L/min
Face Tent limitsUsed mainly for patients who can not tolerate a mask
T-Piece21-100% depending on nebulizer setting Flow rates of 8 to 15 L/min
T-Piece limitsUsed on intubated or trached patients
Trach Mask35-60% O2 depending on nebulizer setting Flow rates of 10 to 15 L/min
Trach Mask limitsAdequate flow shown by mist flowing out the exhalation port at all times
Oxygen Tent21 -50% at flow rates of 10 to 15 L/min Used mainly on children with croup or pneumonia 
Oxygen Tent RisksProblem with leakage ,Fire hazard
High FiO2’s Important PointsHigh FiO2’s (>.60) may not meet the patient’s inspiratory flow demands To insure adequate flow with stable FiO2’s, a special made high flow device should be used or two flowmeters set up to provide at least 40 L/min total flow
High FiO2’s RiskA restriction, such as a kink, or water in the tubing, causes back-pressure into the nebulizer. This decreases the amount of RA entrained and INCREASES the delivered FiO2. increasing flow on a high flow device will not increase FiO2, only total flow
Head box-small, clear plastic enclosures over infant’s head or head and upper torso
Head boxes allowsfor a higher oxygen concentration and more accessibility to patient without disturbing oxygen delivery. Best not to entrain room air into head box because of noise and microorganism introduction (Blender)
air: oxygen entrainment ratios:.60 1:1, .50 1.7:1, .40 3:1, .35 5:1,.30 8:1
QuestionAnswer
Aerobic metabolismsustain life, metabolism that occurs in the presence of oxygen, can produce a lot of energy (ATP)
Anaerobicable to grow and function without air or oxygen – in the cytoplasm
oxygencolorless, tastleless, transparent gas
What does oxygen exist in atmosphere21%
Four classifications of Tissue Hypoxia1. Hypoxemia (hypoxic hypoxia) 2. Hemoglobin defiency (anemic hypoxia) 3. low blood flow (circulatory hypoxia) 4. dysoxia (histotoxic hypoxia)
Hypoxemia (Hypoxic hypoxia)inadequate delivery of oxygen to the lun or from the lung to the blood RESPONDS TO O2
Causes of hypoxemiahypoventilation, breathing at high altitude, shunt (atelectasis), V/Q mismatch, diffusion defects
Hemoglobin Defiency (anemic hypoxia)anemia refers to low amounts of hemoglobin (Hb) in the blood. RESPONDS TO O2
causes of hemoglobin defiency (anemic hypoxia)loss of Hb, decreased Hb production, abnormal Hb, or an impaired chemical combination of Hb (carbon monoxide poisoning)
Low blood flow (circulatory hypoxia)sufficient blood flow is not reaching the tissue and therefore oxygen is not being delivered. O2 THERAPY LIMITED
causes of low blood flow (circulatory hypoxia)cardiac pump failure, CHF, shock, ischemia
Dysoxia (histotoxic hypoxia)poisoning of the cellular oxygen utilization mechanism has occured (the cell is not able to accept oxygen from the blood to utilize it. DOES NOT RESPOND TO O2
Causes of dysoxia (histotoxic hypoxia)cyanide poisoning
Acute hypoxia sign/symptomstachypnea, increase RR, tachycardia, hypertension, increase CO, Arrythymia, restlessness, liver and kidney damage
Chronic Hypoxia signs/symptomspersistent mental and physical fatigue, secondary polycythemia, restlessness, clubbing, increase size of heart (right side failure) (cor pulmonale)
Indication for O2 useDocumented hypoxemia PaO2 thes than 60 mmHg or SaO2 less than 90%
Oxygen toxicityresult of increased FiO2 2 factors: effective dose and duration
Signs/symptoms of oxygen toxicitytachypnea, fatigue, anxiety, irritation of trachea, mild cough, pain in inspiration, N/V, decreased vital capacity
Hypoventilationincreased PaO2
Retinopathy of Prematurity (ROP)increased PaO2, irreversible damage to the retina of an infant due to exposure to high levels in the arterial blood. Greater than 80 mmHg.
Bronchopulmonary Dysplasia (BDP)fibrotic tissue damage caused by the exposure of high levels of inhaled oxygen (FiO2)to the immature lung tissue in a premature baby for a long period of time FiO2 is greater than 40% for more than 24-72 hours
absorption atelectasiscollapse of alveoli as the result of high levels (FiO2) in the inhaled air causing elimination of N2 from the lung.
Shift to RIGHT on curveDecrease affinity Decrease pH Increase in Temp increase 2,3,DPG increase in PCO2
Shift to LEFT on curveincrease affinity (O2 transferred to the blood and HgB) increase in pH decrease in temp decrease 2,3 DPG Decrease in PCO2
Hypoxialack of oxygen at the tissue level
Hypoxemialack of oxygen in the arterial blood (decreased PaO2)
Hyperoxiaincreased levels of O2 to tissues usually due to the use of supplemental O2
Secondary polycythemiaincreased production of RBCs. More RBCS available to carry oxygen to the tissues
cyanosisvisible bluish tinge of the skin and mucous membranes
CaO2content in the amount of oxygn in a substance expressed as volume %.
CaO2 calculationCaO2 = (Hb x 1.34 x SaO2) + (PaO2 x .003) Hemoglobin plasma
normal CaO220.4 vol%
Alveolar Air EquationPAO2 = [Pb – 47)FiO2]- PACO2/8
Normal A-a gradient5-10 mmHg on room air no more than 65 mmHg on 100% oxygen
A-a gradient calculationP(A-a)O2 = PAO2- PaO2
QuestionAnswer
Goals of Oxygen Therapy1. treat hyoxemia 2.Decrease WOB 3. Decrease Myocardial work 4.Lab measures 5clinical problem 6. signs and symptoms
High Flow systemmeet all the inspiratory need or requirements; usually greater than 60 lpm.
Examples of high flow systemsventuri mask (air entrainment mask, CPAP system, ventilator, oxyhood, T-Tube flowby (briggs adaptor)
Low Flow systemnot able to meet all the patients flow or volume needs (inspiratory needs)
Low flow system can deliver FiO2 dependant onRR and volume, proper fit, flow rate, peak insp flow rate
Examples of low flow systemmasks (simple, PRB, NRB), nasal cannula or catheter, tracheostomy collar, oxygen tent
You choose which one to use bypt comfort, desired FiO2 to obtain desired PaO2, required control or precision of FIO2, Humidity needs, type of patient, age
Desired FIO2(desired PaO2 x current FIO2)/current PaO2
How to estimate pt insp needsMV x 3 = insp peak flow
Total flowTIC TAC TOE CHART top left alwayys 100% bottom left always 20%
Non rebreathing maskFiO2 up to 70%; highest without intubating them.
rebreathing maskFIO2 up to 60% (remove valve from mask)
trach maskFIO2 varies (8-12 lpm)
oxygen tentFIO2 40-50% (12-15 lpm)frequent opening and closing of tent causes wide swings in O2 concentration. Temp is lowered by 10-12 degrees
oxyhoodFIO2 21-100% (7- or greater lpm)
What determines the delivered FiO2 on the entrainment port?the size The larger the port the lower the FIO2 The smaller the port the greater the FIO2
What else determines the fiO2?The size of the jet The smaller the jet the lower the fio2
CPAPUSED FOR PATIENTS WITH DECREASE FRC Continuous positive airways pressure. Used to force air into the nasal passage. Useful for patients with sleep apnea, respiratory distress.
How does CPAP work?Air is pushed from the flow generator throught the tubing, the air passes thru nose and into throat, where the slight presure keeps the upper airway open.
CPAP criteriamust be able to breath on own. Beneficial: open collapsed alveoli, decreased WOB, improved distribution, potential increase in secretion removal.
CPAP complicationsbarotrauma, gas in the stomach, decrease venous return
Vapothermthe power of flow. Makes flows 1-40 lpm Tempature ranges from 33-43 C
Anatomical deadspacein airways that does not participate in gas exchange, estmated approx 1ml/lb of IBW (150ml)
Alveolar dead spacevolume of gas ventilating unperfused alveoli
Mechanical dead spacevolume of expired air that is rebreathed through a connecting apparatus or tubing
galvanic fuel cell analyzerreads more to partial pressure, it actually measures PO2 NOT fio2 Can be within +-2 –most common cause of malfunction= low batteries
Goal of humidityto minimize or eliminate a humidity deficit while the patient is breathing a dry medical gas
Definition of inspissatedbeing thick, dry or made less fluid by evaporation
nebulizersolid or liquid particle suspended in a gas that acn be measured and counted
Pulse Oximitrymeasures oxygen saturation of Hb in the blood. measures at greater than 80% match with HR if troubleshooting