内科学-呼吸衰竭知识介绍.pptVIP

Influence of hypoxemia hypercapniaAcid-base balance and electrolytes Severe hypoxia → inhibition of cellular energy metabolism → insufficient energy production, production of lactic acid ↑ → sodium-potassium pump failure → metabolic acidosis, hyperkalemia → PCO2↑ Respiratory acidosis and metabolic acidosis pH is determined by HCO3/PaCO2 ratio Slow CO2 retention → compensated by kidney, decreased elimination of HCO3－ (It takes 1 ~ 3 days for kidney to compensate) pH = HCO3- PaCO2 Clinical manifestationAcute respiratory failure (1) Dyspnea Dyspnea is a early symptom of respiratory failure. Increased breath rates Change in breath rhythm: Cheyne-Stokes respiration, Biot’s respiration Accessory respiratory muscles involved in breathing → “three depressions sign” Cyanosis: Cyanosis is a typical sign of hypoxia, indicating arterial oxygen saturation lower than 90%. The extent of cyanosis is associated with content of reduced hemoglobin. So it is less readily detectable if anemia is present and more readily seen in polycythemia. Peripheral cyanosis is associated with stasis, in which oxyhemoglobin is reduced more than it normally is because of the prolonged peripheral blood transit time, while the PaO2 could be normal. Central cyanosis results from arterial hypoxemia. Clinical manifestationAcute respiratory failure (2) Neuropsychic symptoms: Mental disorder, mania, coma, convulsion Circulatory system: Tachycardia, myocardial impairment, peripheral circulatory failure, hypotension, arrhythmia, cardiac arrest. Digestive system : Hepatic function impairment: ALT↑ Gastrointestinal tract: mucosal erosion, stress ulcer, gastrointestinal bleeding Urinary system: Renal function impairment: BUN↑ Proteinuria, hematuria, casts in urine Clinical manifestationAcute respiratory failure (3) Clinical manifestationChronic respiratory failure Dyspnea: Excessive respiratory effort, prolonged expiration——rapid shallow breathing——slow shallow breathing, Cheyne-Stokes bre