1、Respiratory Failure Respiratory Failure is a syndrome in which the respiratory system fails in one or both of its gas exchange function:oxygenation氧氧&carbon dioxide 二氧化碳二氧化碳 elimination.PaO2 60 mmHg or PaCO2 50 mmHgnAcute respiratory failure is present when alveolar ventilation is inadequately to me
2、et the bodys need;the lung can no longer adequately oxygenate the blood.Mechanisms of type I respiratory failurenMechanisms that may cause hypoxemia and subsequent hypoxemic respiratory failure are:nVentilation-Perfusion(V/Q)mismatch通气血流比例失调通气血流比例失调nShunts分流分流nDiffusion abnormalities弥散障碍弥散障碍1.Alveol
3、ar ventilation肺泡通气不足肺泡通气不足Mechanisms of type I respiratory failurenVentilation-Perfusion(V/Q)mismatch通气血流（通气血流（V/Q)比例失调比例失调:nalter(V/Q)relationship in the lungs or V/Q mismatch,is the most common cause of hypoxemia低氧血症低氧血症.nThe V/Q relationship means that where there is ventilation in the lungs,ther
4、e must be matching blood perfusion to that area for efficient gas exchange occur.nIn the normal lung the overall V/Q ratio is 0.8.Mechanisms of type I respiratory failurenVentilation-Perfusion(V/Q)mismatchnAn alteration or mismatch occurs if there is blood flow to areas of decrease or absent ventila
5、tion or if there is ventilation to areas of decrease or absent blood flow.nExamples of process that cause V/Q mismatch are:pneumoniam肺炎肺炎,atelectasis肺不张肺不张,chronic acute bronchitis,severe emphysema肺气肿肺气肿,asthma哮喘哮喘and pulmonary embolism肺栓塞肺栓塞.Mechanisms of type I respiratory failurenShunts分流分流nA shu
6、nt occurs when blood enters the arterial system动脉系统动脉系统from venous system静脉系统静脉系统without being exposed to ventilated areas通气通气区域区域of the lung.nEssentially,the blood is shunted from the right to the left side of the heart without participating in gas exchange.nBlood that has a PO2 similar to venous b
7、lood is mixed with arterial blood as it enters the left atrium左心房左心房of the heart.Mechanisms of type I respiratory failurenShunts nA shunt can be viewed as extremely V/Q imbalance.nThe most common shunts are extrapulmonary肺外分流肺外分流and include those that occur in congenital heart disease先天性心脏病先天性心脏病thr
8、ough atrial or septal defects房或室间隔缺损房或室间隔缺损or a patent ductus arteriosus动脉导管未闭动脉导管未闭.nIntrapulmonary anatomic shunts肺内解剖相关的肺内解剖相关的分流分流are associated with arteriovenous fistulas动静脉瘘动静脉瘘in congenital defects.Mechanisms of type I respiratory failure3.Diffusion abnormalities扩散异常扩散异常Diffusion abnormaliti
9、es indicates an impairment in the equilibration between the O2 pressure in the alveoli and in the pulmonary capillarie.Disease in which a a diffusion abnormalities may contribute to hypoxemia include:Diffuse interstitial fibrosis弥漫性间质纤维化Collagen vascular disease胶原血管疾病of the lung(e.g.,scleroderma硬皮病,
10、systemic lupus erythematosus系统性红斑狼疮)Asbestosis石棉病Sarcoidosis结节病Interstitial pneumonia间质性肺炎Cardiogenic pneumonic edma心源性肺水肿Mechanisms of type I respiratory failurenAlveolar hypoventilation(PaCO250mmHg):is generalized decrease in ventilation of the lungs with buildup of CO2 in the blood.nAlthough alve
11、olar hypoventilation肺泡通气不肺泡通气不足足is primarily a mechanism of type II respiratory failure,it is mentioned here because in can cause hypoxemia低氧血症低氧血症.nHypoventilation通气过低通气过低is commonly the result of diseases outside the lungs.Pathophysiologic effects of hypoxemianHyhoxemia低氧血症低氧血症 occurs when the amo
12、unt of oxygen in the blood is not adequate to support aerobic metabolism.nCO2 is the waste product of aerobic metabolism有氧代氧代谢谢.When O2 insufficiency persists,the cell must shift from aerobic to anaerobic metabolism无氧代谢无氧代谢.nThe waste product of anaerobic metabolism,lactic acid乳酸乳酸,is more difficult
13、 than CO2 to remove from the body because it has to be buffered with sodium bicarbonate碳酸氢钠碳酸氢钠.nWhen the body does not have adequate amounts of sodium bicarbonate to buffer lactic acid,metabolic acidosis代谢性酸中毒代谢性酸中毒and cell death occur.Pathophysiologic effects of hypoxemianHyhoxemia低氧血症低氧血症and meta
14、bolic acidosis代谢性酸中代谢性酸中毒毒have adverse effect on vital organs,especially the heart and central nervous system(CNS).Permanent brain damage may occur because of depressant effect on the brain.nThe heart try to compensate for the decrease O2 level by increasing heart rate and cardio output.As oxygenati
15、on decreases and acidosis increases,however,the heart muscle is unable to function and a slowing and eventual cessation of cardiac activity occur,resulting in systemic shock全身性休克全身性休克.nRenal function is also impaired,and sodium retention,proteinuria,edema formation,tubular necrosis and uremia may oc
16、cur.nGastrointestinal system alteration include abnormal liver function,abdominal pain and bowel infarction.Mechanisms of type II respiratory failurenMechanisms that may cause type II respiratory failure(hypercapnia)are:nAlveolar hypoventilation通气不足通气不足 1.Ventilation-Perfusion(V/Q)mismatchMechanisms
17、 of type II respiratory failurenAlveolar hypoventilation肺泡过低通气肺泡过低通气nAlveolar ventilation肺泡通气肺泡通气:is the volume of gas气体容量气体容量per breath that is available for gas exchange in functioning alveoli功能性肺泡功能性肺泡.nThe PaCO2 is inversely related to the effective alveolar ventilation.Therefore increase PaCO2
18、indicates decreased alveolar ventilation.nAlveolar hypoventilation is commonly caused by diseases outside the lungs,and often the lungs are normal.Mechanisms of type II respiratory failurenVentilation-Perfusion(V/Q)mismatchnThis may occur in a patient who has an increased work of breathing,most like
19、ly secondary to a large increase in airway resistance.nBecause the patient does not have the energy or ability to overcome this increased resistance,ventilation decreases and PaCO2 increases.Pathophysiologic effects of hypercapnianThe main physiologic feature of hypoventilation通气通气过低过低is hypercapnia
20、高碳酸血症高碳酸血症.This occurs because ventilation is inadequate to remove the CO2 produced by cell metabolism.nSubsequent physiologic effect of hypercapnia are:nDecrease in PaO2The level of CO2 in the blood(PaCO2)the level of CO2 in the alveolar lest space left in alveolar for O2 PaO2 2.Decrease PHRespirat
21、ory acidosis results as CO2 accumulates in the plasma:CO2+H2O H2CO3 H+HCO3 Pathophysiologic effects of hypercapnianSubsequent physiologic effect of hypercapnia are:2.Potassium shift(hypokalemia低钾血症低钾血症)nAs the CO2 accumulates,and with it hydrogen ions(H+),the serum become more acidic H+enters the ce
22、lls and K+move out of the cells to the plasma血血浆浆in an attempt to achieve electorneutrality中和中和电电解解质质.nInitially,serum K+may be increase,but as acidemia酸血症酸血症becomes prolonged or more pronounced,total body K+is depleted as excess extracellular K+is excreted by the kidneys.Pathophysiologic effects of
23、 hypercapnia3.Chloride shift(hypochloremia低氯血症低氯血症)nA low serum chloride lever occurs in acute respiratory failure:as HCO3 move from the cell to the plasma to buffer H2CO3,the chloride ions move into the cell to maintain electroneutrality电解质平衡电解质平衡.Clinical manifestation临床表现临床表现 Hypoxemia低氧血症低氧血症:nD
24、yspnea呼吸困难nRestlessness 烦躁不安nAgitation躁动nDisorientation定向障碍nConfusion精神混乱nDelirium谵妄nLoss of consciousness意识丧失Finding:nCardiac dysrhythmia心律失常nTrachycardia心动过速nHypertensionnTrachypnea呼吸过速nCyanosis(may not be present until hypoxemia is severe)nPale,cool,clammy skin脸色苍白，皮肤湿冷脸色苍白，皮肤湿冷Clinical manifesta
25、tion临床表现临床表现 Hypercapia高碳酸血症高碳酸血症:nHeadachenSomnolence嗜睡nDizziness头晕ncoma昏迷Finding:nHypertensionnTrachycardianDiaphoresis发汗nWarm,flushed skin皮肤温暖潮红皮肤温暖潮红nBounding pulse脉冲脉脉冲脉nAsterixis扑翼样震颤扑翼样震颤 nPapilledema视神经乳头水肿视神经乳头水肿nDecreased deep tendon reflexes深腱反射降低深腱反射降低Diagnostic studies辅助检查辅助检查Evaluation
26、 of oxygenationnArterial blood gas analysis(PaO2,O2 saturation)nPulse oximetry(SpO2)nMixed venous oxygen(PvO2)nShunt equation(Qs/Qt)nAlveolar-arterial oxygen difference D(A-a)O2nAlterial-alveolar ratio(a/A gradient or PaO2/PAO2 ratio)nHypoxemia score(PaO2/FIO2 ratio)Evaluation of ventilation nArteri
27、al blood gas analysis(PaCO2)nCapnography(PetCO2)nTidal volume(Vt)nForced vital capacity(FVC)nMinute ventilation or volume(VE)nNegative inspiratory force(NIF)or maximum inspiratory pressure(MIP)nPhysiologic dead space(VD/VT ratio)Nursing implementation护理措施护理措施 Maintenance of adequate oxygenation维持足维持
28、足够的氧合够的氧合nOxygen administration to keep PaO2 60mmHg:if hypoxemia is secondary to hypoventilation,provision and maintenance of adequate ventilation usually will overcome the problem of gas exchange.Hypoxemia secondary to V/Q mismatch V/Q比例失调比例失调usually responds favorably to the lowest concentration o
29、f O2(administered by mask or cannula)necessary to maintain a PaO2 of at least 55-60 mmHg.1.Hypoxemia secondary to shunting 分流分流is usually refractory to the administration of high concentration of O2 by mask and ultimately requires mechanical ventilation Nursing implementation Maintenance of adequate
30、 oxygenation2.Maintenance of adequate Hb concentration血红血红蛋白浓度蛋白浓度and cardiac output心输出量心输出量To ensure adequate O2 delivery to the tissues,keep the patients PaO2 equal to 60mm Hg or greater will provide adequate O2 saturation.When the PaO2 is 60mm Hg or greater,the Hb is 90%saturated.BP should be mai
31、ntained at the most beneficial level each patient.Usually,a systolic BP of at least 90 mmHg is adequate to maintain perfusion to vital organs.A urine output of 0.5 ml/kg per hour or more is an indication of adequate renal perfusion.Nursing implementation Maintenance of adequate oxygenation3.Preventi
32、on and assessment of tissue hypoxia 缺氧Close observation for clinical manifestations of vital organ hypoxia is needed,including:Mental and neurologic status:clouding of sensorium感觉迟钝感觉迟钝,poor concentration,restlessness,stupor昏睡昏睡,lethargy嗜睡嗜睡,somnolence tremors,slurred speech,depressed tendon reflexe
33、s跟键反射减弱跟键反射减弱,and asterixis扑翼样震颤扑翼样震颤.Cardiovascular status:direct or indirect BP monitoring,cardiac rate and rhythm心律和心率心律和心率,symptoms of right-sided and left-sided heart failure.Fluid and electrolyte levels:continuous or serial monitoring of oxygenation status is essential;serial evaluations of se
34、rum electrolytes are made to determine excesses or deficiencies.Nursing implementation Maintenance of adequate oxygenation4.Measures to decrease stress and promote comfortnThe patient should be maintained in an atmosphere as quite and relaxed as possible.nPositioning the patient for comfort and for
35、the most efficient ventilation is important.nFrequent rest periods needed to be provided and efficient scheduling(pacing)of care,treatments,assessments and diagnostic studies are important to help with conserving the patients energy.nIt is helpful to explain to the patient the possible sensation tha
36、t may be encountered with each new experience(e.g.,suctioning,drawing ABGs)so that coping strategies can be purposefully selected.nMeasures to increase physical comfort are also important:mouth care,removing perspiration-soaked gown,sponging the upper torso躯干上部躯干上部酒精擦浴酒精擦浴.Nursing implementation Imp
37、rovement of alveolar ventilation nMaintenance of patent airway维持气道的开放维持气道的开放Effective coughingAugmented coughing增加咳嗽增加咳嗽may be useful in the patient with neuromuscular weakness or in an exhausted patient.If the patients cough is ineffective in removing secretions,nasopharyneal or nasotracheal suctio
38、ning is indicated.1.Coughing at the end of expiration呼气末呼气末is helpful in the patient with sever airway obstruction because it can cause compression of the more distal or peripheral airways and may help“milk”or move secretions into the proximal airway.Nursing implementation Maintenance of patent airw
39、aynPositioning体位体位nPositioning the patient either by elevating the head of the bed to at least 45 degree(if tolerated)or by using a reclining chair bed may maximize thoracic expansion.nA patient with only one functioning lung should be positioned with the unaffected lung健侧健侧in the dependent position
40、.This position is important in preventing hypoxemia because the“down”lung gets more perfusion.If the diseased lung was“down”,more V/Q mismatch would occur.2.The patient should be lying on the side if there is any possibility that the tongue will obstruct the airway or that aspiration may occur.Nursi
41、ng implementation Maintenance of patent airway3.Suctioning吸引吸引 nAdequate oxygenation and monitoring of the patient are essential during suctioning procedures.nAlthough rarely indicated,bronchoscopy may be used to remove secretions,especially if they are extremely thick and tenacious.Nursing implemen
42、tation Improvement of alveolar ventilation4.Measures to liquefy and mobilize secretionsHumidification加湿加湿Adequate hydration Chest physiotherapy(if indicated)Aerosol and untrasonic nebulization雾化雾化nIf suctioning or other measures to mobilize secretions are ineffective,it may become necessary to inser
43、t endotracheal or tracheostomy tube to facilitate suctioning of secretions.Improvement of alveolar ventilation5.Relief of bronchospasm减轻支气管痉挛减轻支气管痉挛Bronchodilators支气管扩张剂支气管扩张剂nRelief of bronchospasm(if present)will aid in maximal bronchodilatation and increase effective alveolar ventilation.nAdminis
44、tration of an O2-riched gas mixture simultaneously with the bronchodilator may help to alleviate the subsequently hypoxemia.Corticosteroids(when indicated)nCorticosteroids are used in conjunction with bronchodilating agents when bronchospasm and inflammation are present.Nursing implementation Improv
45、ement of alveolar ventilationnVentilation assistanceIf intensive measures fail to improve alveolar ventilation and the patient continues to deteriorate clinically,mechanical ventilation may be instituted to assist or control ventilation;nContinuous positive pressure breathing(CPPB)连续正压呼吸nNoninvasive
46、 positive pressure breathing(NIPPV)无创正压呼吸Nursing implementation Treatment of underlying cause of failurenIn a patient with absolute hypoventilation,the primary problem usually can be diagnosed rapidly,and appropriate therapy initiated.Continuous monitoring of the effects of treatmentnAccurate,clear
47、documentation of subjective and objective assessments on the patients flowchart is an important aspect of care.nA flowchart that shows the patients ABG measurement,vital signs,pulmonary artery pressure,weights,intake and output,medications and dosages,electrolytes,respiratory parameters is extremely
48、 helpful.Nursing intervention and rationalesnIneffective airway clearance related to accumulation of secretion,exudate,sputum in airways,decreased level of consciousness,thoracic and/or abdominal neuromuscular dysfunction,pain and expiratory airflow obstruction nEvaluate patients ability to cough to
49、 determine the need for assistance in removing secretion.nPerform chest physiotherapy to enhance removal of secretions.nPerform tracheobronchial suctioning if coughing is effective.nHumidify inspired air if upper airway is bypassed or O2 is being used at 3L/min to prevent drying of mucosa.nSplint ch
50、est abdominal incision with pillow or hand to reduce pain and allow deeper,more effective breathing and coughing.nTurn q2hr to prevent stasis of secretions and promote optimal ventilationnStabilizer artificial airway to prevent accidental extubation.nEnsure adequate fluid intake of 2-3L/24hr to liqu
