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Test 2/ Resp 121lec
Chap. 10,18,35,38,39
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 |