Presentation on theme: "Chapter 23 Disorders of Ventilation and Gas Exchange"— Presentation transcript:
1 Chapter 23 Disorders of Ventilation and Gas Exchange Essentials of PathophsiologyChapter 23 Disorders of Ventilation and Gas Exchange
2 Pre lecture quiz True/false Pleural, musculoskeletal, and myocardial pain are similar in description and almost impossible to differentiate.Extrinsic or atopic asthma is typically initiated by a type I hypersensitivity reaction induced by exposure to an extrinsic antigen or allergen, such as dust mite allergens, cockroach allergens, and animal dander.Persons with emphysema are often labeled as “blue bloaters” because of the chronic hypoxemia and eventual right-sided heart failure with peripheral edema.Cystic fibrosis is manifested by pancreatic exocrine deficiency and a noted decrease in levels of sodium chloride in the sweat.Hypercapnia refers to an abnormal increase in oxygen levels.
3 Pre lecture quizAsthmaEffusionEmbolismRightTensionA pleural __________ refers to an abnormal collection of fluid in the pleural cavity.__________ is a leading cause of chronic illness in children and is responsible for a significant number of lost school days; it is also the most frequent admitting diagnosis in children’s hospitals.A __________ pneumothorax, a life-threatening condition, occurs when the intrapleural pressure exceeds atmospheric pressure, permitting air to enter but not leave the pleural space.A pulmonary __________ develops when a blood-borne substance lodges in a branch of the pulmonary artery and obstructs the flow.Cor pulmonale refers to __________-sided heart failure resulting from primary lung disease and involves hypertrophy and eventual failure of that ventricle.
4 Causes of Respiratory Failure Hypoventilation hypercapnia, hypoxiaDepression of the respiratory centerDiseases of respiratory nerves or musclesThoracic cage disordersVentilation–perfusion mismatchingImpaired diffusion hypoxemia but not hypercapniaInterstitial lung diseaseARDSPulmonary edemaPneumonia
5 Impaired function of vital centers HypoxemiaPO2 <60 mm HgCyanosisImpaired function of vital centersAgitated or combative behavior, euphoria, impaired judgment, convulsions, delirium, stupor, comaRetinal hemorrhageHypotension and bradycardiaActivation of compensatory mechanismsSympathetic system activation
7 QuestionTell whether the following statement is true or false. Both hypercapnia and hypoxemia will lead to respiratory failure if untreated.
8 AnswerTrue Rationale: In hypercapnia (PCO2 >50 mm Hg), tissues accumulate carbon dioxide; in hypoxemia (PO2 <60 mm Hg), less oxygen is delivered to the tissues. In both cases, gas exchange is impaired, and respiratory failure will result unless the conditions are corrected (with oxygen, mechanical ventilation, etc.).
9 Pleural Disorders Decrease Ventilation Parietal pleura lines the thoracic wall and superior aspect of the diaphragmVisceral pleura covers the lungPleural cavity or space between the two layers contains a thin layer of serous fluid
10 Scenario Mr. K presents himself with a stab wound Now he is having breathing problems, and his breath sounds are diminished on the side with the woundHis trachea seems to be slanting toward the other side of his chest, and his heart sounds are displaced away from the woundHe has an increased respiration rate and blood pressure, is pale and sweating with bluish nail beds, and has no bowel soundsQuestion:Explain the effects of the wound
11 Air enters the pleural cavity PneumothoraxAir enters the pleural cavityAir takes up space, restricting lung expansionPartial or complete collapse of the affected lungSpontaneous: an air-filled blister on the lung rupturesTraumatic: air enters through chest injuriesTension: air enters pleural cavity through the wound on inhalation but cannot leave on exhalationOpen: air enters pleural cavity through the wound on inhalation and leaves on exhalation
14 QuestionTell whether the following statement is true or false. Open pneumothorax is more life-threatening than tension pneumothorax.
15 AnswerFalse Rationale: In open pneumothorax, inhaled air compresses the affected side’s lung, but during exhalation, the lung reinflates somewhat. In tension pneumothorax, a sort of one-way valve exists: the air enters the affected side during inhalation, but is unable to leave when the patient exhales. Therefore, all of this air exerts increased pressure on the organs of the thoracic cage. Unless the pressure is relieved, tension pneumothorax is fatal.
16 Pleural Effusion—Fluid in the Pleural Cavity Hydrothorax: serous fluidEmpyema(em-pī-ē-mə) : pusChylothorax: lymphHemothorax: bloodan accumulation of fluid in one or both pleural cavities, often resulting from disease of the heart or kidneysfluid in the pleural space secondary to leakage from the thoracic duct
18 Pathogenesis of Bronchial Asthma Early PhaseAntigenIgECytokine ReleaseMuscle SpasmLate PhaseMast Cell ActivationVascular porosityEdema and WBC infiltrationEpithelial DamageMuscle Spasm with edema
19 Extrinsic (Atopic) Asthma Type I hypersensitivityMast cells’ inflammatory mediators cause acute response within 10–20 minutesTreat with inhalersAirway inflammation causes late-phase response in 4–8 hoursTreat with antiflamatoryAllergenMast cells releaseinflammatorymediatorsWBCs enter regionand release moreinflammatorymediators
20 Intrinsic (Nonatopic) Asthma Respiratory infectionsEpithelial damage, IgE productionExercise, hyperventilation, cold airLoss of heat and water may cause bronchospasmInhaled irritantsInflammation, vagal reflexAspirin and other NSAIDsAbnormal arachidonic acid metabolism
21 Airway Obstruction in Asthma inflammatoryairwaymediatorsinflammationincreasedepithelialimpairedairwayinjurymucociliaryresponsivenessfunctionbronchospasmedemaairflow limitation
22 Which of the following occurs in asthma? Airway inflammation QuestionWhich of the following occurs in asthma?Airway inflammationBronchospasmDecreased ability to clear mucusAll of the above
23 AnswerAll of the aboveRationale: Inflammatory mediators lead to airway inflammation, edema of the mucous lining of the airways, bronchospasm, and impaired ability to clear secretions. All of these things cause the airways to narrow during an asthma attack.
24 Chronic Obstructive Pulmonary Disorders EmphysemaEnlargement of air spaces and destruction of lung tissueChronic obstructive bronchitisObstruction of small airwaysBronchiectasisInfection and inflammation destroy smooth muscle in airways, causing permanent dilationthe bronchi are distended, characterized by sudden violent coughing and copious expectoration of sputum, and which often become infected
25 Mechanisms of COPD Inflammation and fibrosis of bronchial wall Hypertrophied mucus glands excess mucusObstructed airflowLoss of alveolar tissueDecreased surface area for gas exchangeLoss of elastic lung fibersAirway collapse, obstructed exhalation, air trapping
26 Mechanism of COPD A) Inflammation, Fibrosis B) Hypersecretion of mucus C) Destruction of elastic fibers that hold the airways openAuthor: Please add title.
27 Emphysema Neutrophils in alveoli secrete trypsin Increased neutrophil numbers due to inhaled irritants can damage alveoliAlpha1-antitrypsin inactivates the trypsin before it can damage the alveoliA genetic defect in alpha1-antitrypsin synthesis leads to alveolar damage
33 AnswerEmphysemaRationale: In emphysema, alveolar walls are destroyed. The other chronic pulmonary diseases listed primarily affect the airways.
34 Normal when stabilized & down to 7.3 unstabilized COPD and Blood pHDiscussion:In what range will a COPD client’s blood pH fall?Why?Normal when stabilized & down to 7.3 unstabilizedCO2 +H2O H2CO H+ + HCO3-Venous blood gasRespiratory acidosis(lung induced): Low pH, High CO2, Low HCO3-Metabolic (tissue induced): Low pH, High CO2, Normal HCO3-
35 Consequences of COPDCOPDWhich step in this flow chart will cause the central chemoreceptors to increase respiration?Which will cause the peripheral chemoreceptors to increase respiration?decreasedability toexhalestale air inlungslow O2highlevelsCO2levelshypoxiahypercapnia
36 ScenarioA client with chronic bronchitis has a barrel chest and cyanosis. His pulse oximeter reads 86% oxygenation. His PO2 is 54 mm Hg. His PCO2 is 56 mm Hg.He is put on low-flow oxygen but complains of shortness of breath. Somebody turns the O2 flow up. He is found in a coma with a PCO2 of 59 mm Hg and a blood pH of 7.2.Question:What was the cause of the coma? Why?
37 Cystic Fibrosis Recessive disorder in chloride transport proteins High concentrations of NaCl in the sweatLess Na+ and water in respiratory mucus and in pancreatic secretionsMucus is thickerObstructs airwaysObstructs pancreatic and biliary ducts
39 Cystic Fibrosis Manifestations Discussion:A client with cystic fibrosis is having respiratory problems and:Digestive problemsFlatulenceSteatorrheaWeight lossQuestion:He does not understand why a respiratory disease would cause these problems. How would this be explained to the client?Steatorrhea is the presence of excess fat in feces. Stools may also float due to excess lipid, have an oily appearance and be especially foul smelling.
40 Pulmonary Blood FlowIn a COPD client, exhalation is inefficient and O2 levels in the lungs decreaseIf blood goes through the lungs filled with stale air, it will not pick up much oxygen; it might even pick up CO2Discussion:What will the pulmonary arterioles do?Which side of the heart will be affected? Why?
41 Disorders of Pulmonary Blood Flow Pulmonary embolismPulmonary hypertensionPrimaryBlood vessel walls thicken and constrictSecondaryElevation of pulmonary venous pressureIncreased pulmonary blood flowPulmonary vascular obstructionHypoxemia
44 Right-sided heart failure secondary to respiratory disease Cor PulmonaleRight-sided heart failure secondary to respiratory diseaseDecreased lung ventilationPulmonary vasoconstrictionIncreased workload on right heartDecreased oxygenationKidney releases erythropoietin more RBCs madePolycythemia makes blood more viscousIncreased workload on heart
45 Acute Respiratory Distress Syndrome (ARDS) Exudate enters alveoliBlocks gas exchangeMakes inhalation more difficultNeutrophils enter alveoliRelease inflammatory mediatorsRelease proteolytic enzymes
47 QuestionTell whether the following statement is true or false. Patients suffering from ARDS will be not necessarily be hypoxemic.
48 AnswerFalse Rationale: In ARDS the alveoli are filled with exudate, decreasing the available surface area for gas exchange. If gas exchange decreases, poorly oxygenated or unoxygenated blood is sent to the tissues (hypoxemia).