Respiratory System Respiratory System

John P. McDonough,John P. McDonough, CRNA, Ed.D., ARNPCRNA, Ed.D., ARNP

Pulmonary System StructuresPulmonary System Structures

LungsLungs AirwaysAirways

– (upper & lower)(upper & lower) VasulatureVasulature Chest wallChest wall

LungsLungs

RightRight– upper, middle & lowerupper, middle & lower

LeftLeft– upper & lowerupper & lower

Lobes Lobes segment segment lobules lobules MediastinumMediastinum

– contains heart, great vessels, esophagus contains heart, great vessels, esophagus

Conducting Airways (upper)Conducting Airways (upper)

NasopharynxNasopharynx Oropharynx Oropharynx LaryngopharynxLaryngopharynx

Conducting Airways (lower)Conducting Airways (lower)

LarynxLarynx TracheaTrachea

– divides at the carinadivides at the carina BronchiBronchi

Conducting Airways (lower)Conducting Airways (lower)

Lobar bronchiLobar bronchi Segmental bronchiSegmental bronchi Subsegmental bronchi (nonrespiratory)Subsegmental bronchi (nonrespiratory)

Gas Exchange AirwaysGas Exchange Airways(Respiratory Unit)(Respiratory Unit)

Subsegmental bronchi (respiratory)Subsegmental bronchi (respiratory) Terminal bronchiolesTerminal bronchioles Alveolar ductsAlveolar ducts AlveoliAlveoli

Bronchial WallsBronchial Walls

Epithelial liningEpithelial lining– exocrine gland cells, ciliated cellsexocrine gland cells, ciliated cells

Smooth muscleSmooth muscle Connective tissueConnective tissue

AlveoliAlveoli

25 (birth) 25 (birth) 300 (adulthood) million 300 (adulthood) million Where most gas exchange takes placeWhere most gas exchange takes place

– alveolocapillary membranealveolocapillary membrane Secretes surfactantSecretes surfactant

Pulmonary CirculationPulmonary Circulation

Facilitates gas exchangeFacilitates gas exchange Delivers nutrients to lung tissueDelivers nutrients to lung tissue Reservoir for the left ventricle Reservoir for the left ventricle Filter for the circulation Filter for the circulation Less pressure & resistance than systemicLess pressure & resistance than systemic

– MAP 18 Vs 90MAP 18 Vs 90 100 ml blood / 70-100 m100 ml blood / 70-100 m22 Bronchial circulation Bronchial circulation pulmonary pulmonary

Thoracic CavityThoracic Cavity

Chest wallChest wall DiaphragmDiaphragm LungsLungs PleuraPleura

– visceral & parietalvisceral & parietal Mediastinum Mediastinum Heart & great vesselsHeart & great vessels

Volumes & Capacities Volumes & Capacities

Alveolar dead spaceAlveolar dead space Alveolar ventilationAlveolar ventilation Anatomic dead spaceAnatomic dead space

– 1 ml / pound, 33% of each breath1 ml / pound, 33% of each breath Dead-space ventilationDead-space ventilation Functional residual capacityFunctional residual capacity Minute volumeMinute volume

Volumes & CapacitiesVolumes & Capacities(continued)(continued)

Physiologic dead spacePhysiologic dead space Residual volumeResidual volume Tidal volumeTidal volume Total lung capacityTotal lung capacity Vital capacityVital capacity

Control of VentilationControl of Ventilation

Voluntary Vs involuntary Voluntary Vs involuntary Respiratory center (brain stem)Respiratory center (brain stem) Chemoreceptors Chemoreceptors

Lung ReceptorsLung Receptors

IrritantIrritant– epithelium of conducting airwaysepithelium of conducting airways

Stretch (Herring-Breuer reflex)Stretch (Herring-Breuer reflex)– smooth muscle of airwayssmooth muscle of airways

J-receptors (juntapulmonary)J-receptors (juntapulmonary)– capillaries of alveolar septacapillaries of alveolar septa

ChemoreceptorsChemoreceptors

Monitor pH, PaMonitor pH, PaCOCO22 & Pa & PaOO2 2

Central chemoreceptorsCentral chemoreceptors– near respiratory centernear respiratory center– sense change in pH by Hsense change in pH by H++ ion in CSF ion in CSF

Peripheral chemoreceptorsPeripheral chemoreceptors HH++ changes changes Pa PaCOCO22

COCO22 + H + H22O O H H22COCO33 HCO HCO33 + H + H++

ChemoreceptorsChemoreceptors(continued)(continued)

ventilation ventilation Pa PaCOCO22 COCO22 diffuses across blood/brain barrier diffuses across blood/brain barrier

HH+ + pH pH Center Center rate & depth of respiration rate & depth of respiration Center sensitive to small changes (1-2 Torr)Center sensitive to small changes (1-2 Torr) Chronic disease will desensitize receptorChronic disease will desensitize receptor

ChemoreceptorsChemoreceptors(continued)(continued)

Peripheral receptorsPeripheral receptors Aortic arch, aortic bodies, carotid bodiesAortic arch, aortic bodies, carotid bodies Some sensitivity for PaSome sensitivity for PaCOCO22 & pH & pH Primarily react to PaPrimarily react to PaOO22 Marked hypoxia (PaMarked hypoxia (PaOO2 2 <60 Torr) required <60 Torr) required

Mechanics of BreathingMechanics of Breathing

Muscles are usually for inspiration onlyMuscles are usually for inspiration only 2 major muscles2 major muscles

– intercostal & diaphragmintercostal & diaphragm Accessory musclesAccessory muscles sternocleidomastoid & scalenes sternocleidomastoid & scalenes

Mechanics of BreathingMechanics of Breathing(continued)(continued)

Alveolar surface tensionAlveolar surface tension– surfactant reduces itsurfactant reduces it– Law of Laplace P= (2T/Law of Laplace P= (2T/rr) )

ElasticityElasticity ComplianceCompliance

Airway ResistanceAirway Resistance(Poiseuille’s Law)(Poiseuille’s Law)

50-66% occurs in the nose50-66% occurs in the nose Next highest, oropharynx & larynxNext highest, oropharynx & larynx Should be little in lung conducting airwaysShould be little in lung conducting airways Except in:Except in:

– edemaedema– obstructionobstruction– bronchospasmbronchospasm

Gas TransportGas Transport

Intake of OIntake of O22 by Ventilation of the lungs by Ventilation of the lungs

Diffusion of ODiffusion of O22 across PCM across PCM

Systemic capillaries get arterial bloodSystemic capillaries get arterial blood Diffusion of ODiffusion of O22 into cell into cell

Diffusion of CODiffusion of CO22 into systemic capillaries into systemic capillaries

Pulmonary capillaries get venous bloodPulmonary capillaries get venous blood Removal of CORemoval of CO2 2 by ventilation of the lungsby ventilation of the lungs

Tests of Pulmonary FunctionTests of Pulmonary Function

Spirometry Spirometry – measures volumes and capacitiesmeasures volumes and capacities

Diffusing capacityDiffusing capacity– measure ability for gas transport across PCMmeasure ability for gas transport across PCM

Arterial blood gas analysisArterial blood gas analysis RadiographsRadiographs

– chest x-raychest x-ray

Arterial Blood Gases Arterial Blood Gases

ArtArt VenousVenous pH pH 7.35-7.457.35-7.45 7.33-7.437.33-7.43 PPCOCO22 mm Hg mm Hg 35-45 35-45 41-5741-57 PPOO22 mm Hg mm Hg 80-10080-100 35-4035-40 HCOHCO33 -- mEq/L 22-26 mEq/L 22-26 24-2824-28

SSOO2 2 96-98%96-98% 70-75%70-75%

Base ExcessBase Excess -2 to +2-2 to +2 0 to +40 to +4

Effects of AgingEffects of Aging

Loss of elastic recoilLoss of elastic recoil Stiffening of the chest wallStiffening of the chest wall Alterations in gas exchangeAlterations in gas exchange Increases in flow resistanceIncreases in flow resistance All influenced other factorsAll influenced other factors

– environmental, disease, body size, race & environmental, disease, body size, race & gender gender

S/S of Pulmonary DiseaseS/S of Pulmonary Disease

DyspneaDyspnea– exertional, orthopnea, PNDexertional, orthopnea, PND

Abnormal breathing patternsAbnormal breathing patterns– Kussmaul, “purse lipped”, Cheyne-StokesKussmaul, “purse lipped”, Cheyne-Stokes

Hypo/hyperventilationHypo/hyperventilation CoughCough HemoptysisHemoptysis

S/S of Pulmonary DiseaseS/S of Pulmonary Disease(continued)(continued)

CyanosisCyanosis PainPain ClubbingClubbing Abnormal sputumAbnormal sputum

Conditions Caused by Pulmonary Conditions Caused by Pulmonary DiseaseDisease

HypercapniaHypercapnia HyoxiaHyoxia Acute respiratory failureAcute respiratory failure Pulmonary edemaPulmonary edema AspirationAspiration BronchiolitisBronchiolitis

Conditions Caused by Pulmonary Conditions Caused by Pulmonary Disease Disease (continued)(continued)

Pneumothorax Pneumothorax Plural effusion Plural effusion Pulmonary fibrosisPulmonary fibrosis Pneumoconiosis Pneumoconiosis

Chronic BronchitisChronic Bronchitis

Occurs for at least 3 months, in 2 yearsOccurs for at least 3 months, in 2 years 20 X increase in smokers20 X increase in smokers Inflammation of bronchi (irritants/infection)Inflammation of bronchi (irritants/infection) Muscle hypertrophyMuscle hypertrophy Mucus gland hyperplasiaMucus gland hyperplasia InflammationInflammation H. flu (H. flu (Haemaphilus influenzaeHaemaphilus influenzae) & ) &

Streptococcus pneumoniaeStreptococcus pneumoniae are common are common

EmphysemaEmphysema

Permanent Permanent size of gas exchange airways size of gas exchange airways Destruction of alveolar wallsDestruction of alveolar walls Obstruction from anatomical changeObstruction from anatomical change Primary- 1-2% of casesPrimary- 1-2% of cases

– 11-antitrypsin deficiency (70-80% likelihood)-antitrypsin deficiency (70-80% likelihood)

Secondary most commonSecondary most common

S/S of EmphysemaS/S of Emphysema

Dyspnea on exertion Dyspnea on exertion at rest at rest Often no cough and little sputumOften no cough and little sputum Thin patientThin patient TachypneaTachypnea Prolonged expiration Prolonged expiration

Chronic Obstructive Pulmonary Chronic Obstructive Pulmonary DiseaseDisease

Includes chronic bronchitis & emphysemaIncludes chronic bronchitis & emphysema Next to heart disease as cause of death in Next to heart disease as cause of death in

adults <65adults <65 >33% of all VA patients have COPD>33% of all VA patients have COPD smoking is the primary causesmoking is the primary cause

AsthmaAsthma

Reactive airways and bronchospasmReactive airways and bronchospasm Extrinsic (most common)Extrinsic (most common)

– mast cell activationmast cell activation– triggered by dust, mold, pollen, etctriggered by dust, mold, pollen, etc

Intrinsic Intrinsic – no known allergic causeno known allergic cause– seen in adults >35 and often severeseen in adults >35 and often severe– triggered by drugs, irritants, infections, coldtriggered by drugs, irritants, infections, cold

AsthmaAsthma(continued)(continued)

Inflammation Inflammation hyperresponsiveness hyperresponsiveness Thickening of airwaysThickening of airways

– edema, vascular congestion, edema, vascular congestion, mucus mucus Muscle (bronchial) spasmMuscle (bronchial) spasm

AsthmaAsthma(continued)(continued)

Sensation of chest constrictionSensation of chest constriction Wheezing (inspiratory & expiratory)Wheezing (inspiratory & expiratory) DyspneaDyspnea Cough (often non-productive)Cough (often non-productive) Prolonged inspiration Prolonged inspiration TachycardiaTachycardia Tachypnea Tachypnea