Dyspnea - definitions

Transkriptio

1 Dyspnea - definitions Dyspnea Subjective experience of breathing difficulty Hengenahdistuksen patofysiologiset mekanismit Pathophysiological mechanisms of Awareness of respiratory effort Not a sign! Varying expressions Shortness of breath / ilman loppumisen tunne Distressing breathing / hengitys tuntuu ahtaalta Air hunger / ilmannälkä Stifling sensation / tukahduttava olo Kliinisen fysiologian seminaari Pekka Malmberg, dosentti Hyks, Iho- ja allergiasairaala Breathlessness / hengästynyt Chest discomfort / puristus kurkussa/rinnassa velco dojcinovski: Dyspnea Wassermann and Cassaburi 1988 HENGENAHDISTUS = HENGITYSVAJAUS DYSPNEA = RESPIRATORY INSUFFICIENCY Äkillinen hengitysvajaus on elintoimintahäiriö, jossa happeutumisen häiriö, hiilidioksidin kertyminen tai hengitystyö lisääntyy ja vaatii hoitotoimenpiteitä. Häiriössä happikyllästeisyys (Sa0 2 ) laskee alle 90 %:n tai happiosapaine (PaO 2 ) alle 8 kpa:n. Respiratorinen asidoosi (ph alle 7.35) seuraa hiilidioksidin kertymisestä. de Torres et al. Respir Res 2007

2 Dyspnea What to measure? How to treat? maximal 10 Measuring intensity Borg symptom scale Borg scale very, very severe 9 very severe severe somewhat severe moderate slight very slight just noticeable nothing at all pulmonary group pulmonary (n=85) group normal group (n=109) Pathophysiological mechanisms POWER OUTPUT (% predicted Wmax) Hamilton et al. Chest 1996 Borg scale Hamilton et al. Chest 1996 maximal very, very severe very severe severe somewhat severe moderate slight very slight just noticeable nothing at all angina group (n=114) normal group (n=109) POWER OUTPUT (%predicted Wmax) Control of breathing Cortex (voluntary breathing) Brainstem (automatic breathing) Medulla parenchymal receptors respiratory motoneurons proprioceptive receptors Peripheral chemoreceptors PaCO 2 ; ph PaO 2 ventilation Bronchi Lungs Thorax Respiratory muscles Dyspnea: signaalit Afferentit signaalit: perifeeriset ja sentraaliset kemoreseptorit vagaaliset reseptorit hengitysteissä ja keuhkoissa keuhkokudoksen venytysreseptorit ärsytysreseptorit keuhkoputkien seinämissä C-säikeet keuhkorakkuloiden ja keuhkokapillaarien seinämissä (interstitiaalinen ja kapillaarinen paine) keuhkojen ja rintakehän proprioseptiiviset mekanoreseptorit (lihaskäämit, jänne-elimet) Efferentit signaalit: Respiratoriset motoneuronit kopioituminen ylempiin keskuksiin nucleus tractus solitarius (NTS) ydinjatkoksessa sensorinen cortex (erit anteriorinen insula) + limbinen järjestelmä

3 Neuromekaaninen kytkentä Neuromekaaninen dissosiaatio Hengityslihasten häiriöt Lisääntynyt ventilaation tarve Lisääntynyt hengitystyö Respiratory motor activity (effort) > Sensory feedback of ventilation 1) heightened ventilatory demand 2) increased ventilatory work 3) respiratory muscle abnormalities 4) (blood gas abnormalities) Neuraalinen hengitysyritys > toteutunut hengitys Official statement of ATS: Dyspnea. Mechanisms, assessment and management. AJRCCM 1998 Mod. Sovijärvi ARA. Kliininen fysiologia, 2003 Official statement of ATS: Dyspnea. Mechanisms, assessment and management. AJRCCM 1998 Mod. Sovijärvi ARA. Kliininen fysiologia, 2003 Hengitystyö - breathing work Obstructive lung diseases

4 Breathing work in COPD Breathing work = V x P Dynaamisen hyperinflaation seurauksia Uloshengitysilman virtausrajoitus rasituksessa Flow volume loops during exercise hengitystyö kasvaa! hengityslihasten toiminta heikkenee hengitystiheys kasvaa EELV EELV Borgin asteikko Anssi Sovijärvi 2004 O Donnell and Mahler 2007

5 Ventilation/perfusion and blood gas abnormalities Early onset of lactic acid production Dyspnea: respiratory effort vs. ventilation Increased dead space - > heightened ventilatory demand! Maltais et al. AJRCCM 1996 O Donnell. Proc Am Thorac Soc 2007 Mechanisms of in COPD/astma Increased breathing work increased airway resistance hyperinflation (increased elastic work) Heightened ventilatory demand hypoxaemia (V/Q mismatch, diffusion impairment) hypercapnia (hypoventilation) increased physiologic dead space early onset of lactic acidosis Respiratory muscle weakness overinflation malnutrition Hengenahdistuksen mekanismeja: COPD, astma (Sovijärvi 2003)

6 Hengitystyö (Wbr) Restrictive lung diseases - lung volumes Restrictive lung diseases O Donnel et al. JAP 1998 O Donnel et al. JAP 1998 Restrictive lung diseases - exercise responses Expiratory airflow limitation in ILD Interstitial lung disease increased airway resistance may contribute to Interstitial lung disease Mechanisms of : restrictive lung diseases neuromuscular diseases Increased breathing work increased elastic work increased respiratory rate Heightened ventilatory demand hypoxaemia (diffusion impairment) increased VD/VT vagal afferent discharge from J receptors? hypercapnia (hypoventilation in NM diseases) Respiratory muscle weakness NM diseases

7 Hengenahdistuksen mekanismeja: restriktiiviset ja neuromuskulaariset sairaudet Obesity - lung volumes Obesity: flow volume loops Obeesi Normaali elastic work airway resistance work (Sovijärvi 2003) Ofir et al Mechanisms of : obesity juxtacapillary J receptors diffusion impairment Increased breathing work increased elastic work (chest wall) increased airway resistance (low FRC) increased respiratory rate Heightened ventilatory demand increased metabolic demands due to body weight hypoxaemia (V/Q abnormalities due to low FRC) Congestive heart failure (CHF) wet lung = stiff poorly ventilated alveoli hypercapnia (hypoventilation) Respiratory muscle weakness decreased compliance of chest wall

8 Increased dead space in CHF Wasted ventilation in CHF CHF: Early anaerobic threshold CHF decrease of structures involved in tissue respiration (cells, mitochondria, enzymes) decreased peripheral circulation decrease in C(a-v)O2 VE CHF Normal AT = SV * C(a-v)O2 VO 2 Sovijärvi et al. Clin Physiol 1992 Sovijärvi et al Flow limitation in CHF Chronic CHF: mechanisms of Johnson et al. Chest 1999 Heightened respiratory demand early accumulation of lactic acid ergoreceptor overactivity (myopathy) increased VD/VT hypoxaemia in acute CHF (diffusion impairment) vagal afferent discharge by C fibers (J receptors) Increased respiratory work decreased lung compliance increased airway resistance Respiratory muscle weakness decreased peripheral circulation (myopathy) Hyperventilation syndrome (HVS)

9 Kinnula and Sovijärvi. Respiration 1993 Inappropriate ventilation in HVS Physiologic causes of Increased ventilatory impedance (work): Obstruction of flow asthma COPD emphysema tracheal stenosis endobronchial disease (primary lung carcinoma) Decreased compliance (elastic work) intrinsic (diseases involving lung parenchyma) interstitial fibrosis adult respiratory distress syndrome congestive heart failure extrinsic (not involving lung parenchyma) obesity kyphoscoliosis pleural processes ascites Physiologic causes of Heightened ventilatory demand: increased VD/VT obstructive lung diseases pulmonary embolus heart failure increase in respiratory drive exercise hypoxemia: secondary to any cause metabolic acidosis: diabetic ketoasidosis and renal failure anaemia panic disorders: hyperventilation syndrome Physiologic causes of Respiratory muscle weakness: neuromuscular diseases poliomyelitis severe hypothyreoidism hyperinflation due to obstructive lung disease LOPUKSI - MITEN VÄHENTÄÄ HENGENAHDISTUSTA? Perussairauden hoito Vähennä ventilatorista tarvetta metabolinen kuorma lihaskunnon parantaminen lisähappihoito central drive opiaatit anksiolyytit Vähennä hengitystyötä keuhkoputkia laajentava lääkitys laihdutus emfyseeman reduktiivinen pneumoplastia (volume reduction surgery) noninvasiivinen/invasiivinen ylipaineventilaatiohoito ym Paranna hengityslihasten funktiota ravitsemus hengityslihasten harjoitteet asento