Question Answer
Define P50. Indicated what will happen to the normal value with a shift to the right and left. The partial pressure at hemoglobin is 50 percent saturated with oxygen.A shift to the right will increase the P50 while a shift to the left will decrease the P50 Normal P50 27 mmhg
Co2 diffuses across the A-C membrane how many times faster than O2 20 times faster
What is dead space ventilation? Volume of inspired air that does not reach the alveoli for gas exchange
What is shunted blood? What can cause it? V/Q ratio decreases PAco2 increases PaO2 decreases.CausesCOPD(emphysema, bronchitis, asthma)Restrictive lung disease( Pneumonia, fibrosis, hypoventilation)
What factors can shift the ODC to the left? Hgb has more affinity for O2causes Hgb to hold O2 Alkalosis-Ph increasesCo2 DecreasesTemperature increases2, 3 DP6 decreases
Explain how capillary shunting is refractory to oxygen O2 cannot diffuse capillary blood because of restriction
List the causes of hypoxemia 1. Low alveolar oxygen tension2. Diffusion defects3. Ventilation- perfusion mismatches4. Pulmonary shunting
Which compartment of the blood transports the most Co2 63% bicarbonate
Discuss the Bohr Effect and Haldane Effect Haldane Effect – deoxygenated blood enhances loading of CO2 and oxygenated blood enhances the offload of CO2 Bohr Effect- the effect of PCO2 and Ph on the oxyhemoglobin curve.
What is anatomic shunt? What is the normal value we see? When more O2 does not help refractory to oxygen therapy 3% normal value
List the factors that move the ODC to the right Temperature IncreasePh increasePCO2 increaseDPG increase
In the upright lung is the V/Q high or low at the base Highest at the apex and lowest at the bases
What conditions make RBC concentration of 2,3, DPG decrease Decrease in Ph Store bloodIncrease hypoxiaAnemiaIncrease Ph
What is the first sign of hypoxemia? Tachycardia
If the ventilation decreases but perfusion stays the same has the V/ Q increased or decrease Decrease
Define respiratory acidosis and respiratory alkalosis Respiratory acidosis or acute ventilation failure- hypoventilation caused by narcotics barbiturates decrease Pao2 increase PaCo2Respiratory Alkalosis- POCO2 decrease with hyperventilation Ph increase
Calculate RQ if the tissue consumes 290ml of oxygen and produces 215ml of CO2 CO2/O2 = .74
Define alveolar dead space and anatomical dead space Alveolar is ventilated but not perfused with blood-air is flowing but no gas exchange blood is stopped in a capillary amount of space is unpredictableAnatomical volume of gas in conducting airways equals 1ml/lbs of body wt.
HCO3 to H2CO3 ratio 15:1.Is this acidosis or alkalosis? Acidosis because it is below 20:1
Define physiological dead space Sum of anatomic and alveolar dead space
How much CO2 does the body produce normally at rest in one minute? How much oxygen is consumes normally in one minute? 200mlCO2/min 250mlO2/min
Is a HCO3 to H2CO2 ratio 23:1 acidic or alkalotic? Alkalosis because the 23:1 is higher then 20 making it alkalosis
What happens PaO2 and CaO2 in hypoxic hypoxia? What happens to them in anemia hypoxia? Hypoxic hypoxia- PaO2 decrease CaO2 increaseAnemic hypoxia- normal Pao2 CaO2 decreases
If the ventilation increases but perfusion stays the same what happens to the V/Q ratio? Increases
What is acute ventilatory failure? What are it causes? Increase PaCO2 decrease PaO2CausesCOPDGeneral anesthetics Head trauma Neurological disordersHypoventilation caused by an overdose of narcotics
Discuss the concept of the ion gap. What is the normal range for the ion gap. Is the pt. acidosis caused by fixed acids or by a loss of HCO3Na+=140meq/l Cl=105 meq/l HCO3= 24mq/l9-14meq/l a gap increase 14 represents metabolic acidosis
Be sure you can interpret ABGs Ph 7.35 to 7.45Below 7.35 acidosis Above 7.45 alkalosisPaCo2 35 to 45Below 35 acidosis Above 45 alkalosisHCO3 22 to 26 below 22 acidosis above alkalosis
Causes respiratory acidosis and respiratory alkalosis respiratory acidosis Causes: COPD, general anesthetics, head trauma neurological disorderrespiratory alkalosis Causes: pain aniexty fever brain inflammation hypoxia stimulant drugs

Pt. factors in selecting O2 therapy equipment severity/cause of hypoxemia, age group, degree of consciousness and alertness, presence/abscence of tracheal airway, stability of minute ventilation and mouth vs.nose breathing pt
High flow devices meet inspiratory demand, inspiratory demand equals 3*minute volume, CAN NOT deliver fixed FIO2, ordered in FIO2 while low flow devices ordered in lpm, breathing pattern irrelevant & fixed performance device
HAFOE(high air flow oxygen enriched) air entrainment masks using venturi principle, gas flow through restriction increasing forward velocity; creates greater negative lateral pressure and entrains either air/water
High flow sysytems supply a given o2 concentration @ a flow =/exceeding the pt peek inspiratory flow, uses air-entrainment/blending system can ensure a fixed FIO2
Venturi Mask aerosol face mask and veni mask, has big holes in mask to allow for high flows, fixed FIO2 humidifier not required; gets humidity from air that is entrained, can use aerosol by connecting tubing to collar provided
entrainment ratio 100-FIO2/FIO2-20(or 21 if 35% or LESS)
Oxygen hood/oxihood need large bore tubing & nebulizer bottle, constant FIO2 to babies, flow has to be set high enough to flush out CO2, 5-10 lpm; noise pollution becomes a real problem for babies, measures FIO2 @ babies nose; not @ top of hood(care about babies mouth & nose
Incubator environmental delivery system, warms child to 35 degree Celsius, provides O2 enriched environment, humidifies, noise a problem [Red flag closes entrainment port; flag up = closed(100% FIO2)& flag down = open(40% O2)]
Oxygen tent(crouptent) todays tent provide for children, oxygen enriched environment, high humidity, temperature control
Oxygen adder simplest to create, use 2 flowmeter and use same entrainment ratio
Blender simplest to use, attaches to a 50psi wall outlet and mixes the air and CO2 internally and gives you desired amount by turning the knob where you want it
Hyperbaric Oxygen Chamber chamber makes person breathe oxygen @ pressure higher than 1 atom, used to treat decompression sickness and air embolus in divers, CO poisoning in firefighters,anaerobic infections, burns and cyanide poisoning
Monoplace Chamber 1 person occupancy 8-10 feet long and 3 feet wide
Multiplace Chamber walkin unit for 2 or more people
Indications for Hyperbaric Oxygen Therapy most common acute conditions are Air embolism and Carbon monoxide poisoning. Others are decompression sickness, cyanide poisoning, gangrene, anaerobic infection, skin grafts and wound healing
Contridictions for Hyperbaric Oxygen Therapy high fever, high PCO2(breathe big volumes in w/ high CO2-knockout hypoxic drive), URI(causes pressure on brain), Seizures, Sinusitis, Pneumothorax, Obstructive airway(makes brain think dont need to breath)
Helium Oxygen Therapy The value of helium as a therapeutic gas is based on its low density & can decrease the work of breathing for patients with airway obstruction
Guidelines for use of Heliox therapy helium must always be mixed with O2, heliox can be prepared at the bedside/used from premixed cylinders, heliox should be delivered to patients via a tight fitting non breathing mask with flow
Trouble shooting and hazards of Heliox Therapy poor vehicle for aerosol transport, reduces the effectiveness of coughing, badly distorts patient voice & hypoxemia can be a problem
Humidity Therapy physiologic control of heat-moisture exchange,nose is an effective humidifier/heater, mouth is less effective, artificial airway puts stress on the lower airway to provide heat & moisture
Heat-moisture exchange primary role of the upper airway
Physical Principles governing humidifer function temperature- the higher the temp of the gas the more water it can hold, surface area-affects the rate of evaporation, contact time-evaporation increases as contact time increases
Humidifier is a device that adds molecular water to gas & this occurs by evaporation of water from a surface
Indications for humidification and warming of inspired gases administration of dry medical gases @ flows greater than /equal to 4Lpm, following intubation of the patient, managing hypothermia & treating bronchospasm caused by cold air
Influence of temperature Temperature is the primary factor influencing evaporation; warmer the air the more H2O vapor it can hold
Humidity Deficit difference between the amount of water vapor in alveolus air and inspired air
Must make up the difference to prevent impairment of cillia, decreased mucus movement, retained secretions, bacterial infiltration, atelectasis & pneumonia
insensible body deficits things you CAN’T see like water loss through skin and lungs appox 900ml/day
sensible body deficits things you CAN see like urine and gi tract approx 1200ml/day
additive deficits are not essential for body deficits; includes things like vomiting/diarrhea. approx 1000ml fluid loss; lots of moisture lost in 24 hours
Goals of humidity therapy ensure water vapor content is sufficient to meet patient physiologic need, increase water vapor content of dry therapeutic gases to approximate ambient conditions, provide inspired gas near BTPS for patient with artificial airway
Rationale for using humidity supply water vapor for comfort & provide 100% RH @ body humidity(47mmhg and 44mg/L)
Hazards of Humidity Therapy alternation of normal heat and water exchange caution should be used in using heat humidifiers for pt w/fever, fluid retention. pediatric & neonatal care very sensitive because heat and water exchange more easily disrupted infection primarily w/aerosol
humidifier that produce aerosol carry bacteria
bubble humidifier breaks an underwater gas stream into small bubbles, usually unheated, goal is to raise the water vapor content of the gas to ambient levels, size of bubbles determined by size of openings and gas flow rate; RH body temp of approx 35%
Passover Humidifier directs gas over a water surface; resrvior,membrane, wick type
Cascade Humidifier function reservior type of passover humidifier, sterile water goes through tower down immersion tube through diffuser grid and forms bubbly froth when heated. provide RH @ body temp of about 100%. One way valve prevents water from going back into machine
Wick humidifier porous hygroscopic material partially submerged in water reservoir. wick achieves RH @ body temp of about 100%
Advantages of wick humidifier saturation @ high flow & less resistance to flow
Heat- Moisture Exchanger most often a passive humidifier that has been described as an artificial nose, doesn’t add heat/water to system, captures exhaled heat and moisture which is then applied to the subsequent inhalation
Things to think about w/ HME adds dead space to circuit, excessive secretions render it useless, it acts as a filter and pt will not get meds being administered
Reservior and Feed System heated humidifiers can evaporate more than 1L/day to avoid constant refilling, the devices use large water reservior and/or gravity feed system
Bland Aerosol Therapy consists of liquid particles suspeneded in a gas(oxygen or air), a variety of liquids may be used, sterile water(entrain water into oxygen)& sterile saline( hypotonic,isotonic, hypertonic)
pulmonary circulation arises from right ventricle, carries entire Cardiac Output through the lungs to left heart & capillaries cover about 90% of alveolar surface
Functions of lungs gas exchange @ the alveolar- capillary membrane(primary function), pick up O2 and drop off CO2, Alveolar -Capillary membrane controls fluid exchange in lungs. production, processing and clearance of variety of chemicals and blood clots
ventilation movement of gas into and out of lungs
pressure force per unit area
flow volume per unit time
resistance impedance to flow
elastance ability of object to return to original shape after having been distorted by some external force
compliance ease of distensibility
airway resistance resistance to ventilation caused by movement of gas through airways
transairway pressure pressure difference between airway opening and alveoli
pressure gradient why gas moves in/out
transpulmonary pressure pressure difference between airway opening and intrapleural pressure
alveolar distending pressure pressure difference between alveolus and pleural sapce
transthoracic pressure pressure required to inflate/deflate the lungs and chest wall
surface tension force exerted by like molecules @ surface of a liquid expressed in d/cm
Formula for surface tension P=2*ST/R(bubbles of gas have 2 interfaces so P=4*ST/R
elastance when you exhale it is ability of lungs to return to original shape
compliance when you inhale it is ease with which lungs can be distorted; measured as change in volume/change in pressure. measure of inflation of lung, expressed as L/cmH20 or mL/cmH20. decreased lung compliance = increased elasticity
elaticity measured as change in pressure/change in volume
FRC(functional residual capacity) remains in lungs as a result of opposing forces of pulmonary system and thoracic system
Dynamic compliance measure of compliance obtained while breathing(change in volume/ change in pressure)
static compliance measure of compliance with no flow. put ventilator in inspiratory pause or occlude exhalation valve and measure pressure @ point with no air flow
minute ventilation (VE) normal 5-10L/min total volumne moved in and out per minute VE=RR*VT VE driven by CO2 production and subject size
alveolar ventilation amount of fresh gas reaching alveoli per minute determined by VT, dead space, and RR VA=(VT-VD)*RR VA is always less than VE due to dead space
Dead space Ventilation physiologic dead space= anatomic + alveolar deadspace Vdamat: volume in conducting airways 1mL/lb of IBW(2.2mL/Kg) vDALV: alveoli recime gas but no perfusion/have ventilation that exceeds perfusion measured clinically using the Bohr equation
Lung volumes tidal volume, inspiratory reserve volume, expiratory reserve volume & residual volume
lung capacity total lung capacity, inspiratory capacity, functional residual capacity & vital capacity
tidal volume volume of air inhaled/exhaled @ rest 500mL
inspiratory reserve volume maxium volume of air inhaled after normal inspiration 3000mL
expiratory reserve volume amount of gas exhaled from lungs after resting exhalation 1000mL
residual volume volume of gas remaining in lungs after maxium exhalation 1500mL
inspiratory capacity maxium amount of air inhaled from resting exhalation 3500mL
vital capacity maxium amount of air exhaled after a max inspiration 4500mL
functional residual capacity amount of gas left in lungs after normal exhalation 2500mL
total lung capacity max amount of air in lungs after max inspiration 6000mL
General goals and Clinical Objectives of O2 Theray correct documented/suspected acute hypoxemia, decrease the symptom associated w/ chronic hypoxemia, decrease the workload hypoxemia impose on the cadiopulmonary system
Assessing the need for O2 therapy laboratory documentation(PaO2,SaO2),specific clinical problem(pt suspected of carbon monoxide poising)& clinical findings @ the bedside(tachypnea,tachycardia,confusion,etc)
Precautions & hazards of Supplemental O2 oxygen toxicity, depression of ventilation(occurs in COPD pt w/ chronic hypercapina), retinopathy of prematurely(excessive blood O2 levels cause retinal vasconstriction & necrosis),absorption atelectasis(can occur w/ an FIO2 above 0.50)
hypoxemia abnormal deficiency of oxygen in blood
hypoxia abnormal condition in which oxygen available to the body’s cells is inadequate to meet their metabolic needs
Hypoxia occurs when O2 concentration of aterial blood decreases, caediac output/perfusion is low, & combo of the above 2
Four kinds of hypoxia hypoxic, anemic, stagnant & histotoxic
Anemic hypoxia 2types, absolute anemia & relative anemia
Absolute anemia reduction in blood Hb concentration caused by hemorrahage/poor erythropoiesis
erthropoiesis does not make rbc adequately/fast enough
relative anemia may be enough Hb but not normal transport
Stagnant hypoxia drop in blood flow(shock/ischemia) that leads to circulatory failure
Ischemia no blood to tissues, localized drop in perfusion(ex. MI/CVA)
hypotoxic hypoxia oxygen is ther but tissues can not use it. cellular use of O2 is abnormal like w/ cyanide poison. Hb is ok but tissue is bad
physiologic effects of hypoxia “drunk,” minor changes, hyperinflation is an early response leading to tachycardia, changes in intellectual performances and visual activity
pulmonary complications common after surgery involving the upper abdomen/thorax, complications include atelectasis, pneumonia, and acute respiratory failure
lung expansion therapy utilized to prevent/correct respiratory complications in the postoperative period
resorption atelectasis occurs when mucus plugs block ventilation to selected regions of the lung; gas distal to the obstruction is absorbed by the passing blood
passive atelectasis is caused by persistent breathing w/ small tidal volumes
factors associated w/ causing Atelectasis obesity, neuromuscular disorders, heavy sedation, history of lung disease, surgery near the diaphragm, bed rest & poor cough
clinical signs of atelectasis history of recent major surgery, tachycardia, tachypnea, fine/late-inspiratory crackles, bronchial/diminished breath sounds, increased density & signs of volume loss on chest x-ray
incentive spirometry has been the mainstay of lung expansion therapy for many years, devices provide visual cues to the patient when a desired inspiratory volume of flow is reached, & proved to be effective in high-risk patients
equipment for incentive spirometry simple, portable and inexpensive. Are either flow/volume oriented; flow-oriented are more popular because they are smaller
administration of Incentive spirometry determined by careful patient assessment( high-risk patient)
effective patient teaching demonstrate and then observe the patient, patient should sustain maximal inspiratory effort for 5-10seconds & follow up
IPPB means intermittent positive airway pressure breathing
IPPB uses positive airway pressure to expand the lung, treatments last 15-20 minutes & exhalation is passive
indications for IPPB patients w/ atelectasis not responsive to other modalities such as incentive spirometry & patient at high risk for atelectasis who can’t perform incentive spirometry
contraindicating intermittent positive airway pressure breathing therapy tension pneumothorax, tracheoesophagueal fistula, esophageal surgery, ICP>15mmHg, hemodynamic instability, active/untreated TB & active hemoptysis
types of administration of IPPB are preliminary planning and implementation
preliminary planning therapeutic outcomes set, evaluate alternatives and baseline assessment of the patient
implementation equipment prep, patient orientation, patient positioning, adjusting parameter, flow & pressure
selecting an approach choose the modality that is the safest, simplest and most effective
The respiratory therapist should evaluate the following before choosing a specific modality level of patient cooperation, amount of pulmonary secretions, & patient’s spontaneous vital capacity
laboratory analysis measurements of fluids/tissue that must be removed from the body, measurements made w/ an analyzer, monitoring is an ongoing process by clinicians where they obtain & evaluate physiological process; done w/ a monitor
Invasive procedures require insertion of a sensor/collection device into the body
Noninvasive procedures monitoring is a means of gathering data externally
In general, invasive procedures provide more accurate data but carry greater risk
Monitored Values All data must be evaluated in context of overall clinical presentation, instrument inaccuracy- recalibrate, artifacts, factitious results-true but temporary(cough), treat the pathology, not the errant number
All values monitored must be… considered in relation to what pathology has altered them an how best to treat the pathology
Capnometry the measurement of Co2 in respiratory gases, graphic display of Co2 levels as they change during breathing, used in patients undergoing general anesthesia/mechanical ventilation
capnometer measures Co2, functions on the basis that Co2 absorbs infrared light proportion to the amount of Co2
main stream technique places an analysis chamber in the patients breathing circuit
side stream technique pumps a small volume of gas from the circuit into a nearby analyzer
normal capnogram shows an PCO2 of ZERO at the start of the expiratory breath, soon afterwards, the PCo2 level rises sharply and plateaus as alveolar gas is exhaled
end-tidal PCo2(PETCO2) is used to estimate deadspace ventilation and normally averages 1-5 mmHg less than PaCo2
Physical works on “pauling” principle
O2 is.. susceptible to paramagnetism and is paramagnetic, alters design of magnetic force, drawn to strongest part of the magnetic field; when this occurs O2 displaces nitrogen which is diamagnetic
paramagnetic anything that is attracted by the poles of a magnet and becomes parallel to the lives of the magnetic force
diamagnetic repelled by forces of magnet. moves at right angles to lives of the force of a magnet
pauling dry gas drawn into chamber containing magnetic field, gas must be anhydrous; H20 vapor exerts pressure, thermal conductivity based on ability of O2 to cool electrical wire more so than air
cooler the electric wire less resistant to flow of electrons & greater the current passing through the wire
wheatstone bridge has 2 reference chambers on one side that contain room air. A constant cooling by room air maintains current at constant level. Other side is a measuring chamber & a calibrating polentiometer, 2 sides connected in middle by voltmeter
potential difference is converted into FIO2(wheatstone bridge)
chemical analyzers most precise method of measuring FIO2; know that they exist but they are too large to be economical
electro chemical analyzers for measuring FIO2, most bedside systems to measure use electrochemical principles
The two most common O2 analyzers polargraphic(clark) electrode and galvanic fuel cell
Response times for clark electrodes 10-30seconds
response times for galvanic fuel cells 60seconds
a gold cathode in the presence of O2 will produce the following reaction -o2+h20=4electrons=4oh(hydroxyl ions)
galvanic fuel cell incorporates a semi permeable membrane made of Teflon, uses O2 to create current between electrode; as long as the electrode is exposed to O2 the current is continual. therefore life of cell depends on duration & frequency of all
Polargraphic electrode( Clarke electrode) faster than galvanic, uses battery to polarize electrode, has improved response, time w/ same chemical reaction, composed of 2 electrodes immersed in a potassium chloride electrolyte solution
how does current occur with polargraphic electrode at the silver anode oxidation of chloride ion to silver chloride occurs; releasing electrons and causing a current
The greater the partial pressure of O2 the greater the current produced
Clarke electrode is used in ABC machines & must be calibrated at different altitudes because measures partial pressure
If the analyzer fails to calibrate the problem could be related to low batteries, sensor depletion, or electronic failure
Pulse oximetry(fifth vital sign) provides noninvasive measurement of SaO2(referred to as SPO2), monitors only oxygen; NOT ventilation & significant limitations
tissue oxygenation depends on CaO2(PaO2 & SaO2), cardiac output and oxygen uptake
troubleshooting O2 analyzers best way to avoid problems is through preventative maintenance
increase the flow and you decrease the entrainment ratio
the LOWER the FIO2 the MORE air you entrain; therefore the MORE parts you have… you can use lower flow and still meet inspiratory demand when lower FIO2’s can be used
when the upper airway is bypassed the humidity is provided by the lower respiratory tract(say cascade/wick humidifier)
must have water vapor, it adds with pink silica gel crystal to RH 100%, and electric circuitry is flammable so not used Wheatstone bridge
what covers the tip of a Clarke electrode tip of the Clarke electrode is covered with polyprolene membrane that allows the slow diffusion of O2 from blood/gas being analyzed
oximetry is the measurement of hemoglobin saturation using spectrophotometry, works because each substance has its unique pattern of light absorption, each form of hemoglobin has its own pattern of light absorption
pulse oximetry uses a oximeter to measure blood oxygen levels and hemoglobin saturation, multiple lights pass through the sample to measure multiple hemoglobin species such as Hbo2, HbCo and not Hb, results reported as Spo2,
perfect CO2 and range 40mmHg; 35-45mmHg
acidotic 45/above
alkalotic 35/above