gas exchange and respiratory function part one by linda self
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Gas Exchange and Gas Exchange and Respiratory FunctionRespiratory Function
Part OnePart One
By Linda Self
Review of TermsReview of TermsCyanosis—influenced by polycythemia and
anemiaClubbing-Schamroth methodHemoptysisPerfusion—actual blood flow through the
circulationVentilation----movement of gas into and out
of the alveoliDiffusion—oxygen and CO2 exchanged from environment>trachea>bronchi>bronchioles
and alveoli Compliance-measure of the elasticity,
expandability, and distensibility of lungs, influenced by surfactant
Ventilation—Perfusion Ventilation—Perfusion RatiosRatiosNormal lung is 1:1Shunts: when perfusion exceeds
ventilation, a shunt exists. Blood bypasses the alveoli w/o gas exchange occurring.
Pneumonia, atelectasis, tumors, mucous plugs
Ventilation-Perfusion Ratios Ventilation-Perfusion Ratios cont.cont.
High ventilation-perfusion ratio---Dead space
Ventilation exceeds perfusionAlveoli do not have adequate
blood supply for gas exchange to occur
Pulmonary emboli, pulmonary infarction, cardiogenic shock
Ventilation-Perfusion Ratios Ventilation-Perfusion Ratios cont.cont.Silent unit—absence of
ventilation and perfusionSeen in pneumothorax and
severe ARDS
Neurologic Control of Neurologic Control of VentilationVentilationPhrenic nerveRespiratory center in medulla and
ponsCentral chemoreceptors in medulla,
influenced by chemical changes in csf
Peripheral chemoreceptors in aortic arch and carotid arteries, respond first to changes in PaO2, then PaCO2 and pH
Gerontologic Gerontologic ConsiderationsConsiderationsDecreased strength of
respiratory musclesDecreased elasticityIncreased respiratory dead spaceDecreased number of ciliaDecreased cough and gag reflexIncreased collagen of alveolar
walls
Respiratory AssessmentRespiratory AssessmentHealth HistoryRisk factors for respiratory disease-
genetics, smoking, allergens, occupational and recreational exposure
Dyspnea, orthopneaCough, ?productiveChest painCyanosisLung soundsClubbing—indicates chronicity
Diagnostic EvaluationDiagnostic EvaluationPFTs-assess respiratory function,
screening, assess response to therapy FVC—vital capacity performed with a
maximally forced expiratory effortForced expiratory volume—FEV1—
volume of air exhaled in the specified time during the performance of forced vital capacity. FEV1 is volume exhaled in one second.
FEV1/FVC%--ratio of timed forced exp. volume to forced vital capacity
Diagnostic Evaluation--Diagnostic Evaluation--ABGsABGs1. pH2. evaluate the PaCO2 and HCO3-3. Look to see if compensation has
occurred. If CO2 is >40, respiratory acidosis; If HCO3- <24, metabolic acidosis; next look at value other than primary disorder, if moving in same direction as primary value, compensation is underway.
ABG’s continuedABG’s continuedCan have two acid-base disturbances at
same timeThis can be identified when the pH does
not explain one of the changes, e.g., pH 7.2PaCO2 52HCO3 13Notice that oxygen level is not a
component in determining the acid-base balance
ABGs cont.ABGs cont.Normal values for arterial gases:
7.35-7.45, CO2 35-45 mm Hg, HCO3 22-26 mEq/L, O2 80-100 mm Hg, BE +/-2 mEq/L
sat >94%Mixed Venous Blood: 7.33-7.41,
CO2 41-51 mm Hg, HCO3 22-26 mEq/L, O2 35-40 mmHg, BE +/- 2mEq/L, sat 60-80%
See chapter 14 of text
AcidosisAcidosisResults in decreased myocardial
contractility and a decreased vascular response to catecholamines. May interfere with metabolism of certain medications
AlkalosisAlkalosisCan radically impair oxygen
release from RBCs. For this reason, use bicarbonate infrequently in code situations
Other diagnostic studiesOther diagnostic studiesPulse oximetry—not reliable in severe
anemia, high CO levels, or in shockCO2 monitoring—tells us ventilation to
lungs is occurring, that CO2 is being transported to lungs, exp. CO2 indicates adequate ventilation
CulturesImaging—chest xray, CT, MRI, lung
scans (inject isotope, inhale radioactive gas), PET
BronchoscopyThoracentesisothers
Sleep ApneaSleep ApneaAssociated with frequent, loud
snoring with breathing cessation for 10 seconds or long, at least 5 episodes per hour, followed by awakening by a snort when O2 levels drop
May be associated with obesityDecreased pharyngeal tone
(related to alcohol, sedatives, neuromuscular disease)
Sleep ApneaSleep ApneaDiagnosed by polysomnography
(ECG, EEG, EMG, pulse oximetry)More common in menHigh risk for CAD, cerebrovascular
disease and premature death.Results in hypoxia and
hypercapnia which trigger sympathetic response. Can lead to dysrhythmias and elevated BP
Sleep Apnea signs and Sleep Apnea signs and symptomssymptoms
Excessive daytime sleepinessFrequent nocturnal awakeningInsomniaLoud snoringMorning headachesPersonality changesSystemic hypertensionDysrhythmiasPulmonary hypertension, cor
pulmonalepolycythemia
ManagementManagementNurse educates patientAvoid alcohol and sedativesWeight lossCPAP or BiPAP—CPAP prevents
airway collapse, BiPAP makes breathing easier and results in lower airway pressure
UvulopalatopharyngoplastyTracheostomyProvigil, Provera, Diamox, Triptil may
help
Cancer of the LarynxCancer of the LarynxSquamous cell most common—95%Increasing in womenMore common in African AmericansMost common in individuals
between 50-70 years of ageCarcinogens—tobacco, alcohol,
exposure to asbestos, wood dust, cement dust, tar products, leather and metals
Most often affects glottic area
Laryngeal CancerLaryngeal CancerClinical manifestations1.Hoarseness of greater than two weeks
duration2.Persistent cough3.Sore throat4.Dysphagia5.Dyspnea6.Ulceration7.Foul breath8.Cervical adenopathy9.Weight loss10.Debilitation
Assessment and DiagnosisAssessment and DiagnosisH&PLaryngoscopy with
biopsy/staging of diseaseCT and MRI to assess adenopathy
and further stageing
Laryngeal Cancer—Laryngeal Cancer—ManagementManagement
Depends on staging of tumorOptions include surgery,
radiation and chemotherapySometimes combination therapyEnsure any dental problems
corrected, usually before other treatments
Surgical ManagementSurgical ManagementLaser surgery, supraglottic
laryngectomy, hemilaryngectomy, total laryngectomy
In case of total laryngectomy, advanced cancer present
Laryngeal structures removed including portion of trachea. Results in permanent loss of voice and permanent tracheostomy
Often will have radical neck dissection involves removal of sternocleidomastoid muscle, lymph nodes, jugular vein, surrounding soft tissue
Post-operative CarePost-operative CareUsually ICU postopMonitor airway, VS,
hemodynamic status and comfort level
Monitor for hemorrhageMonitor for infectionMonitor tracheal stomaHave extra trach at bedside (of
same size!)
Post-operative CarePost-operative CareMay be on ventilator initiallyWill have trachEnsure humidity at all timesMay have split thickness skin graft or
trapezius or pectoralis muscle grafts—ensure side of flap or graft not in dependent position
May have PCA NG, G tube or jejunostomy tube may be
in place—nutrition importantSpeech rehab, esophageal speech,
electrolaryngesSupport group
Patients with chronic Patients with chronic obstructive pulmonary obstructive pulmonary
disordersdisordersCOPD—nonreversible Includes emphysema and chronic
bronchitisCan co-exist with asthma Present with s/s in middle life and
incidence increases with ageFVC and FEV1 decreased
Chronic BronchitisChronic BronchitisDisease of airwaysIncreased mucous production,
decreased ciliary activity, inflammation, reduced alveolar macrophage function
EmphysemaEmphysemaLobule—physiologic unit of lung consisting
of bronchiole and its branches (alveolar ducts, sacs and alveoli)
Two types—panlobar and centrilobularIn Panlobartype—destruction of
bronchiole, alveolar duct and alveoli; little inflammation, hyperexpanded chest, work on exhalation
Centrilobar type—derangement of the V/Q ratios, chronic hypoxemia, hypercapnea, polycythemia and right sided heart failure
See p. 688 for schematic
EmphysemaEmphysemaRisk factors include:1.Cigarette smoking2.Occupational dusts, chemicals,
pollution3.Deficiency of alpha1-antitrypsin,
protective enzyme that protects lung parenchyma from injury---seen in Caucasians
COPD clinical COPD clinical manifestationsmanifestationsChronic cough, sputum
production, and dyspnea on exertion (DOE)
Weight loss commonIncreased number of respiratory
infectionsIn primary emphysema, will have
“barrel chest”
Diagnosis of COPDDiagnosis of COPD
Thorough H&PSpirometry to evaluate airflow
obstructionFEV1/FVC will be less than 70%Reversibility will be testedChest xray ABGsScreening for alpha1-antitrypsin
deficiencyClassified by five stages—0 through
IV (see p. 690)
Medical ManagementMedical ManagementSmoking cessation will slow
progressionMay use Chantix, Wellbutrin,
nortriptyline, clonidineBronchodilators—beta agonists,
anticholinergics, methyxanthines, combinations, nebulized medications, inhaled and systemic corticosteroids
Influenza and pneumococcal vaccinesOxygen therapy—usually started in
severe COPDHigh fat, low CHO diet
Oxygen Therapy in COPDOxygen Therapy in COPDPreviously felt that high levels of
O2 affected hypoxic driveNow thought that Haldane effect
relates to ability of hgb to carry O2 and CO2. With increased levels of O2, increased saturation, increased CO2 load w/o being able to expel it. So, increased hypercapnia.
Surgical Management Surgical Management Bullectomy—have blebs or
enlarged airspaces that do not contribute to ventilation
Lung volume reduction surgery—may improve quality of life but not life expectancy
Lung transplantation
Nursing ManagementNursing ManagementKey is educationBreathing exercisesInspiratory muscle training—
breathe against a set resistanceActivity pacing Self-care activitiesPhysical conditioningOxygen txNutritional therapyCoping measures
BronchiectasisBronchiectasisChronic, irreversible dilation of the
bronchi and bronchiolesCaused by: inflammation d/t recurrent
infections damaging bronchial walls, thick sputum and decreased mucociliary clearance; genetic disorders like CF, idiopathic causes
Results in atelectasis, fibrosis, VQ mismatch
R/O TB or other pathologyTx-chest PT, smoking cessation,
continuous abx tx, possible surgical resection of affected areas
AsthmaAsthmaChronic inflammatory disease
characterized by mucosal edema, airway hyperreactivity, and mucous production
Largely reversibleAllergy is strongest predisposing
factorPoorly controlled asthma can
result in remodeling. Bronchial muscles and mucous glands enlarge, alveoli hyperinflate and subbasement fibrosis.
AsthmaAsthmaCells that play role in
inflammation of asthma include: leukotrienes, bradykinins, prostaglandins, mast cells, neutrophils, eosinophils
Beta receptor stimulation results in decrease of chemical mediators and causes bronchodilation
Three most common symptoms of asthma are cough, dyspnea and wheezing
AsthmaAsthmaFamily, environmental and
occupational history is necessaryComorbid conditions like GERD,
drug-induced asthma and allergic bronchopulmonary aspergillosis may be present
AsthmaAsthmaTriggersComplications—status asthmaticusRescue and maintenance
medicationsPeak flow monitoring—measure
highest airflow during a forced expiration. See asthma action plan on p. 715. Height, age and sex are variables to consider in personal best determination.
Status AsthmaticusStatus AsthmaticusSevere and persistent asthma that does
not respond to conventional therapy. Can be precipitated by infection, irritants, ASA or others
Severe bronchospasm with mucous plugging leading to asphyxia
Labored breathing, engorged neck veins, cough, wheezing
ABGs indicatedO2, IV fluids, burst of steroids, short
acting corticosteroids, possibly magnesium sulfate
Nurse monitors, administers fluids and meds, ensures no irritants in environment
AtelectasisAtelectasisClosure of collapse of alveoli Often occurs in postoperative
setting and in those who are immobilized
Can result from any obstruction that blocks air to and from alveoli
AtelectasisAtelectasisClinical manifestations—cough,
sputum, low grade fever. In severe cases, tachycardia, tachypnea, central cyanosis
Chest xray may reveal patchy infiltrates, crackles will be heard over affected area, O2 saturation may be lower than 90%
AtelectasisAtelectasisPrevention—turning, mobilizing
patient, deep breathing maneuvers, incentive spirometry, secretion management such as suctioning, nebulizers, chest PT
Management—IPPB, chest PT, nebulizer tx, bronchoscopy, possible ventilator support, thoracentesis
PneumoniaPneumonia
Is an inflammation of the lung parenchyma caused by microorganisms
Community acquired—usually caused by: Strep pneumo, Hemophilus influenza, Legionella, Mycoplasma pneumoniae, Chlamydia, viral
Hospital acquired—Pseudomonas, Staph aureus, Klebsiella
PneumoniaPneumoniaPneumonia in the
immunocompromised patient—Aspergillus, Pneumocystis, Mycobacterium tuberculosis
Aspiration pneumoniaIs the most infectious disease
causing death in the United States
Pathophysiology of Pathophysiology of pneumoniapneumoniaArises when normal flora has
been aspirated, when host defenses are down or from bloodborne organisms that enter the pulmonary circulation
Affects ventilation and diffusion—will have adequate perfusion but not ventilation
Risk factors for Risk factors for PneumoniaPneumoniaConditions resulting in mucous
obstruction (cancer, smoking, COPD)ImmunosuppressionProlonged immobilityDepressed coughNPO, ETT, NG or OG tubesAlcohol intoxicationAdvanced ageMedications that depress
respirations
Clinical Manifestations of Clinical Manifestations of PneumoniaPneumonia
Not possible to diagnose a certain type by manifestations alone
May be sudden in onset with fever, chills and pleuritic pain as seen in pneumococcal pneumonia
May be gradual in onset with low grade fever, HA, pleuritic pain, myalgias and pharyngitis
OrthopneaPurulent sputum
Diagnosis of PneumoniaDiagnosis of PneumoniaHistoryPhysical examSputum culturesBlood culturesChest xrayPossible bronchoscopy
depending on severity
Medical ManagementMedical ManagementAntibiotic depending on Gram stainOften treat empirically, intervene
promptlyCAP-tx with Zithromax, Biaxin, doxy,
or fluoroquinolone. With comorbidities, may use Augmentin, Vantin, Ceftin, and a macrolide or doxy. Symmetrel for Flu A, Tamiflu for Flu A/B. Bactrim for PCP.
Medical Management Medical Management cont.cont.
Hospital acquired—IV antibiotics such as second generation cephalosporins, carbapenems, fluoroquinolones. If MRSA, use vancomycin, Zyvox. For Pseudomonas, use Timentin, Unasyn, and an aminoglycoside.
Viral pneumonia is supportive care only.
Hydration is important in all types.
Other treatmentsOther treatmentsAntihistaminesNasal decongestantsAntipyreticsMonitoring O2 saturation,
possibly ABGsSerial xrays
Gerontologic Gerontologic ConsiderationsConsiderationsIn elderly the classic s/s of cough,
chest pain, sputum production and fever may be absent
May be difficult to distinguish heart failure from pneumonia
Xrays particularly helpful in this population
Nursing the patient with Nursing the patient with pneumoniapneumonia
Frequent assessment—night sweats, fever, chills, cough, lung sounds
Encourage hydration as hydration thins and loosens secretions
Humidification w/or w/o oxygenEncourage cough, chest
physiotherapyPromote restMaintain nutritionPromote patient education
Respiratory Care Respiratory Care ModalitiesModalitiesNasal cannula—up to 6L/min.
Delivers up to 42% oxygenSimple mask—flow rate 6-8L/min.
Delivers 40-60% oxygen. Partial rebreather mask—flow rate is
8-11L/min. Delivers 50-75% oxygen.Nonrebreather mask—flow at 12
L/min. Delivers 80-100% oxygen.Venturi mask—4-6 L/min, 6-8 L/min.
Deliver respective oxygen concentration of 24, 26, 28 or 30, 35, 40% oxygen. Most accurate delivery.
Respiratory Care Respiratory Care ModalitiesModalitiesOxygen Hypoxemia—decrease in arterial
oxygen tension in bloodHypoxia—decrease on oxygen supply
to tissuesOxygen toxicity—can occur if
delivering >50% for longer than 48h. Caused by free radical production.
Signs/symptoms of oxygen toxicity—paresthesias, fatigue, refractory hypoxemia, alveolar atelectasis, alveolar infiltrates
Consider alveolar collapse with high levels of oxygen
TracheostomyTracheostomySurgical procedure in which an
opening is made into the tracheaTracheostomy tubeTemporary or permanentUsed to bypass an upper airway
obstruction, allow removal of tracheobronchial secretions, permit long term use of mechanical ventilation, to prevent aspiration in unconscious patient or to replace endotracheal tube
Complications of Complications of tracheostomytracheostomyBleeding, pneumothorax, air
embolism, aspiration, subcutaneous or mediastinal emphysema, recurrent laryngeal nerve damage
Airway obstruction from accumulation of secretions ,tracheoesophageal fistula, tracheal ischemia
Nursing Care of the Patient Nursing Care of the Patient with Tracheostomywith Tracheostomy
Initially, semi-fowler’s position to facilitate ventilation, promote drainage, minimize edema, and prevent strain on the sutures
Allow method of communicationEnsure humidity to trachSuction secretions as neededManage cuff—usually keep pressure
less than 25 mm Hg but more than 15 mm Hg to prevent aspiration
Endotracheal IntubationEndotracheal IntubationPass ETT via nose or mouth into
tracheaMethod of choice in emergency
situationPassed with aid of a laryngoscopeETT generally has a cuff, ensure
that cuff pressure is between 15-20 mm Hg.
Use warmed, humidified oxygenShould not be used for more than
3 week
Preventing Complications Associated Preventing Complications Associated with Endotracheal and Tracheostomy with Endotracheal and Tracheostomy
TubesTubesAdminister adequate warmed humidityMaintain cuff pressure at appropriate
levelSuction as neededMaintain skin integrityAuscultate lung sounds—ETT can lodge
in right mainstem bronchusMonitor for s/s of infectionMonitor for cyanosisMaintain hydration of patientUse sterile technique when suctioning
and performing trach careMonitor O2 sat
Mechanical VentilationMechanical VentilationUsed to control patient’s
respirations, to oxygenate when patient’s ventilatory efforts are inadequate, to rest respiratory muscles
Can be positive pressure or negative pressure
Key for the nurse is assess patient—not the ventilator
Indications for Mechanical Indications for Mechanical VentilationVentilation
PaO2 <50 mm Hg with FiO2 >0.60PaO2 >50 mm Hg with pH <7.25Vital capacity < 2 times tidal volumeNegative inspiratory force < 25 cm
H20Respiratory rate > 35 bpm( *vital capacity is dependent on age,
gender, weight and body build. Usually is twice tidal volume. If < 10mL/kg, will need respiratory assist)
Classification of Ventilators—Classification of Ventilators—Negative PressureNegative Pressure
Used for patients with polio, muscular dystrophy, ALS, myasthenia gravis
Examples include the iron lung chamber, pneumo wrap and tortoise shell (portable devices with rigid shell to create a negative pressure)
Ventilators—positive Ventilators—positive pressurepressureInflate lungs by exerting positive
pressure on the airwayUsually requires trach or ETTUsed in home setting as well Pressure cycled, time cycled and
volume cycledNoninvasive positive pressure
ventilation is an option, does not require ETT
Positive Pressure Positive Pressure VentilatorsVentilatorsPressure cycled ventilators—
delivers air until reaches a preset pressure, then cycles off, then passive expiration
Can vary as patient’s airway resistance or compliance changes
Volume delivered thus will vary and may compromise ventilation
Positive Pressure Positive Pressure VentilatorsVentilatorsTime cycled rarely seen in adults
(used in newborns and infants)Volume cycled—most common.
Delivers a preset volume usually 8-10ml per kg
Noninvasive positive pressure ventilation—CPAP and BiPAP. CPAP indicated for sleep apnea, BiPAP esp. useful to avoid intubating patients and in those with neuromuscular disorders, other conditions.
Ventilator ModesVentilator ModesAssist control Intermittent mandatory controlSynchronized intermittent
mandatory ventilationPressure support—assists SIMV,
applies pressure plateau to spont. resp. during inspiratory phase
New modes incl. computerized systems
Initial Ventilator SettingsInitial Ventilator SettingsTidal volumeLowest concentration of oxygen to
maintain PaO2 80-100 mm HgPeak inspiratory pressureMode—AC or SIMV, possibly PEEPSensitivity so that patient can
trigger the vent. With minimal effortCheck ABGs after being on vent. for
20-30 minutes
Remember………..Remember………..If patient becomes agitated,
confused, tachycardic, blood pressure increases for some unexplained reason, assess for hypoxia and manually ventilate on 100%.
If patient’s heart rate slows and BP drops during suctioning, possible vagal stimulation. Stop suctioning and give 100% O2.
Bucking the ventilatorBucking the ventilatorOccurs when the patient’s
inspiration and expiration are out of synch with the ventilator
Anxiety, hypoxia, increased secretions, hypercapnia, others
Sedatives, muscle relaxants, paralytics may be necessary
Monitoring and Managing Monitoring and Managing Potential Complications Potential Complications
associated with the associated with the ventilatorventilatorSee handout
Alterations in cardiac functionBarotrauma and volutrauma
resulting in pneumothoraxVagal stimulationPulmonary infections—use
chlorhexidine gluconate in oral care
Weaning from the VentilatorWeaning from the Ventilator—criteria for weaning—criteria for weaning
Vital capacity—amount of air expired after maximum inspiration. Should be 10-15mL/kg.
Maximum inspiratory pressure-used to assess the patient’s respiratory muscle strength—should be at least -20cm H20
Tidal volume—volume of air that is inhaled or exhaled during effortless breath.
Weaning criteria cont.Weaning criteria cont.Minute ventilation—equals resp
rate times tidal volume. Normal is 6 L/min.
PaO2 greater than 60 mm Hg with FiO2 <50%, stable vital signs, adequate nutritional status
Would refrain from sedating patient during weaning
Thoracic SurgeriesThoracic SurgeriesPneumonectomyLobectomySegmental resectionLung volume reductionothers
Risk factors for thoracic Risk factors for thoracic surgery related atelectasis surgery related atelectasis
and pneumoniaand pneumoniaPreop—age, obesity, poor nutritional
status, smoking, preexisting lung disease, comorbid states
Intraoperative—thoracic incision, prolonged anesthesia
Postop—immobile, supine, inadequate pain management, prolonged intubation/ventilator, presence of NG tube, LOC, lack of education
Care of Patient after Care of Patient after ThoracotomyThoracotomy
Maintain airway clearancePositioning-lobectomy turn either
side,pneumonectomy turn on affected side, segmental resection varies per doctor
Chest tube drainage/careRelieve painPromote mobilityMaintain fluid volume and
nutrition
Care of Patient after Care of Patient after Thoracotomy—monitor and Thoracotomy—monitor and
manage potential manage potential complicationscomplications
Monitor respiratory statusVitalsFor dysrhythmiasFor bleeding, atelectasis and
infectionMonitor chest tube drainage, for
leaks, for tube kinks, for excessive drainage
Chest tube drainage Chest tube drainage systemsystem
Based on three bottle systemDrainage chamberWater sealWet or dry suctionMonitor water seal for bubblingCheck for subq emphysemaGently milk tube Occlusive dressingMonitor drainage
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