Dyspnea Definition DyspneaisdefinedasanawarenessofdifficultyinbreathingItisthereforeasymptom usuallydescribedbythepatientas shortofbreath whetherthesensationisduetoactualdifficultyinbreathingorisessentiallyanawarenessofhyperventilation Ifthesymptombecomesstriking italwayscompanieswithdilatationofnares cyanosis useofaccessorymusclesofrespirationandabnormalitiesofrespiratoryrate depthorrhythm RespiratorydiseasesCirculatorydiseasesPoisoningHematologyNeuropsychogenicfactors Etiology Respiratorydyspnea Causedbyabnormalventilationandgasexchange reductioninventilatorycapacity hypercapniaandhypoxemiaresultingfromrespiratorydisease Threeclininaltypes InspiratorydyspneaExpiratorydyspneaMixeddyspnea Inspiratorydyspnea Tendstooccurprimarilywhenthereisobstruction suchasinflammation edema tumorandforeignbody inlarynx tracheaandmajorbronchi Characterizedbythedepressionsigh inwhichvisibleindrawingoverthesternalnotch thesupraclavioularspaces theintercostalspacesandtheepigastriumintheinspirationcanbeseen Oftenaccompaniedbyacoarse lowpitchedinspiratorywheezinganddrycough Expiratorydyspnea Expiratorydyspneaisduetothedecreaseoflungelasticityandspasmnarrowingofthebronchiolesandsmallerbronchiasinemphysema bronchialasthmaandasthmaticbronchitis Expirationisprolongedandlabouredwithwheezing Mixeddyspnea Occurswiththeextensivelungdisease suchasseverepneumonia pulmonaryfibrosis massiveatelectasis pleuraleffusionandpneumothorax Resultsinthedecreaseofventilatorsandgasexchangecapacity Breathingisdifficultduringbothinspirationandexpiration Cardiacdyspnea Cardiacdyspneaisusuallyattributabletopulmonaryvascularcongestionresultingfromtheleftand orrightheartfailure Cardiacdyspnea InLeft sidedheartfailure complianceisreduced andtherefore ventilationisdecreasedtotheedematouslungregionsandvitalcapacityreduced Alveoliarestiffandmoreworkisneededtoovercomeelasticrecoil thehighalveolarpressurewillstimulatestretchreceptorandinitiatetheinflationreflexresultinginearlyturningoffofinspirationandanincreaseinrespiratoryrate Cardiacdyspnea Thedyspneacausedbyright sidedheartfailureislessseverethanthatonecausedbyleft sided Mechanism 1 Thepressureofrightatrialandsuperiorvenacavaisthenaturalstimulusofrespiratorycenter 2 Thedecreaseofoxygencontentandtheaccumulationoftheacidmetabolites suchaslactic stimulaterespiratorycenter 3 Therestrictionoftherespiratorymovementcausedbyenlargementofliverresultingfromcongestion ascitesandpleuraleffusion Cardiacdyspnea Symptomsofcongestiveheartfailurecancauseorthopneaandparoxysmalnocturnaldyspneawhenelevated fillingpressureispresent orthopnea Orthopneaisdifficultyinbreathinginthesupineposition thismayberelivedbysittingup whichreducesthedegreeofpulmonarycongestionbypoolingbloodinthelowerextremitiesandloweringleftventricularfillingpressures improvingthediaphragmaticmovement increasingvitalcapacity paroxysmalnocturnaldyspnea Symptoms Thepatientawakesshortofbreathatnight butoftenobtainreliefbysittingupforaperiodoftime Inthemostadvancedcases thepatientsbecomeacutelydyspneic cyanoticandveryfrequentlyproducefoamysputumtingedwithblood Signs Moistralesatthebothlungbases tachycardia wheezingandbronchospasm themarkedlyaccentuatedsecondheartsoundinthepulmonicarea Mechanism Supinepostureforsleepresultsinresorbtionofextracellularfluidintotheintravascularspace causingariseinfillingpressure Theparoxysmaldyspneaistermedascardiacasthma Itcanbeseeninthehypertensiveheartdiseaseandcoronaryheartdisease paroxysmalnocturnaldyspnea Toxicdyspnea Inthemetabolicacidosis uremiaanddiabeticketosis theacidmetabolitesstimulatetherespiratorycenter causingdeepandregularrespirationwithsnoring TheoverdoseofmorphineandpentobarbitalcandepressrespiratorycentercausingdeeprespirationorCheyne Stokessrespiration Neuro Psychogenicdyspnea Inpatientssufferingfromcerebrovasculardiseases intracranialhemorrhage elevatedintracerebralpressure therespiratorycenterlosesthebloodsupplyoriscompressed Therespirationbecomesdeep slowandirregular Insomecasesthedyspneamaybepsychogenic whichischaracterizedbyrepetitivedeep sighingrespirationwithnumbnessofextremitiesorlips cheiropedalspasm Thesearealsomanifestationsofacutehypocapniaandrespiratoryalkalosis Hematologicaldyspnea Insevereanemia sulfhemoglobinemia methaemoglobinemiaorcarbonmonoxidepoisoningthedecreaseofoxygen carryingcapacityandoxygencontentdevelopabnormalrespirationandincreasedheartrate Therespirationratealsoincreasesinshockwhichstimulatesrespirationcenterbecauseofhypotension AccompaniedSymptomParoxysmaldyspneawithwheezing Dyspneawithchestpain Dyspneawithfever Dyspneawithcoughandpurulentsputum Dyspneawithcoma ParoxysmaldyspneawithwheezingItispresentinbronchialasthmaandcardiacasthma Paroxysmalseveredyspneaisoftenseeninacutelarynxedema foreignbodyinbronchi massivepulmonaryembolism andspontaneouspneumothorax Dyspneawithchestpain Itisfrequentlyobservedinlobarpneumonia pulmonaryinfarction spontaneouspneumothorax acuteexudativepleurisy acutemyocardialinfarction andbronchialcarcinoma Dyspneawithfever Itiscommonlynotedinpneumonia lungabsc