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39 Cards in this Set
- Front
- Back
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hypercapneic
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metabolic rate > alveolar ventilation
CO2 production > CO2 excretion ABG definition: respiratory acidosis - increase PaCO2 (>50) with decrease pH (<7.30) |
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hypoxemic
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inadequate oxygenation
- decrease PaO2 (<60) with O2 sat < 90% |
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most common type of respiratory failure?
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high work of breathing
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poor respiratory drive
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brain stem suppression
- drugs: narcotics & benzodiazepines - endocrine/metabolic (hypothyroid) brainstem damage - trauma (damage pace maker) intracranial P increase stimulates hyperventilation, so this is rare - disease (ALS & polio) |
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poor muscle strength
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muscular disorders
neurologic disorders drugs |
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muscular disorders in acute resp failure
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malnutrition
electrolytes abnormalities dystrophies, myositities |
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neurologic disorders that produce poor muscle strength
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ALS, polio, MS
spinal cord injury myasthenia gravis |
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drugs that produce poor muscle strength
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neurmuscular relaxing agents (surgery)
steroids (common) |
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high work of breathing components
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flow/resistive work
stretch work volume work |
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flow/resistive work
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upper airway obstruction
- aspriation - produces stridor lower airway obstruction - wheezing |
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stretch work
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lung parenchymal stiffness (pneumothorax; stretch alveoli to get air in)
chest wall or pleural stiffness - kyphosis - seizure: all muscles contract |
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volume work
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high metabolic activity
high dead space (PE) |
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determine if respiratory drive intact
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breathing pattern
bedside breathing measurements measured with respirometer |
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breathing pattern in determining of respiratory drive intact
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mental status
respiratory distress: dyspnea accessory muscle use |
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bedside breathing measurements in determining intact resp drive
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resp rate: normal about 10 breaths/min
machine vs total breaths tidal volume : Vt = 5 ml/kg = 350 ml total minute ventilation : VE = 5 L/min |
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is muscle strength adequate
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general muscle strength
- standing from chair - turningn over or sitting up in bed - hair combing, window opening chest vs ab breathing - paradoxical pattern = diaphragm fatigue bedside strength measurements - vital capacity : VC = 3x tidal volume or > 1 L - maximal inspiratory P : MIP < -20 cmH2O with MIP meter |
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is flow work increased?
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exam
- wheezing and/or stridor - thick copious secretions - pursed lip breathing (to not let air P drop as fast; ppl with flopy airways) - barrel chest - long exhalation time (decrease I:E ratio) PFTs - decreased FEV (in 1st sec) - decreased peak exp flow rate (PEFR) |
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is stretch work increased
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exam
- lungs = rales or crackles - chest wall deformity (scoliosis) - dullness to percussion - ab distension, prego, ascites |
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PFT if stretch work increased
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increase restriction; decrease forced vital capacity
increase chest stiffness; decrease static compliance |
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volume work increased exam
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tachypnea: RR > 20
lungs may be clear CXR may be normal |
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volume work increased PFT
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increase resting minute ventilation : 15-20 L/min
increase dead space : increase Vd/Vt 30% = 50% - unable to exercise (can't recruit) - Vd/Vt increase with exercise; should decrease |
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finding that best characterizes impaired resp drive
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apnea with resp acidosis
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83 yo female inpt; hip replacement 2 days ago; unarousable for 2 hrs (stroke?); cyanosis, no distress, unresponsive, RR 4; acute respiratory acidosis
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normal lung function
hypoxemia = alveolar hypoventilation elderly pt recent surgery & narcotics given comatose, no focal findings, bradypnea no resp distress acute alveolar hypoventlation ;normal A-a = impaired resp drive - not a lung prob = brainstem suppression suppression by drugs support ventilatioin & give narcotic antagonist |
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narcotic antagonist
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naloxone: Narcan
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impaired resp drive Ddx
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brainstem suppression by drugs or endocrine/metabolic
brainstem damage by trauma or disease (brainstem stroke) drugs are most common cause of impaired resp drive |
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18 yomale transferred from another hospital for mechanical ventilation; SOB x 1 wk; cyanosis, confusion, distended neck veins, muscle wasting, accessory muscle use, unable to stand or turn over, RR 32; chronic respiratory acidosis
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normal lung function
hypoxemia = alveolar hypoventilation young person, generalized wkness & muscle wasting resp distress, tachypnea chronic alveolar hypoventilation - normal gradient =poor muscle strength; not a lung problem - muscular disease treat precipitating cause support ventilation : - acutely or chronically |
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poor muscle strength Ddx
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muscular disease
- drug induced myopathies (steriods, EtOH) - non drug induced myoopathies : acquired (myositities) or genetic (muscular dystrophy) neurological disease - neuronal : polio - NMJ: myasthenia gravis |
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tx for poor muscle strength
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treat precipitating cause
- correct electrolyte diroders - treat acute infection - correct malnutrition support ventilation - acutely: oral intubation, ventilator - chronically: tracheostomy, home ventilator |
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likely findings in pt with high work of breathing
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accessory muscle use
tachypnea hyperpnea |
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35 yo male 1 wk hx fever, cough, SOB, worsening SOB on ward x 48 hrs; intubatd after near arrest; resp distress, diffuse crackles; diffuse patch infiltrates on CXR; refractory hypoxemia; normal acid base balance
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grossly abnormal lung function
refractory hypoxemia: R-L shunt young pt, febrile respiratory illness diffuse alveolar filling pattern on radiograph shunt typee of hypoxemia = airspace dz = high work of breathing (stiff) = primary lung problem (stretch work, not flow) ARDS: legionella pneumonia |
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Ddx of high work of breathing
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flow work
stretch work 1. parenchymal (airspace disease) a. alveolar filling process (radiograph) = cardiogenic pulmonary edema (age) = non cardiogenic pulmonary edema = atypical pneumonia b. interstitial disease 2. pleural disease 3. chest wall disease volume work |
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ARDS
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a precipitating cause could be legionella pneumonia
refracotry hypoxemia difuse infiltrates pulmonary wedge P < 15 stiff lungs: edema predictable behavior for injured lungs: similar physiology regardless of cause |
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intrapulmonic shunting in early ARDS
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edema & microatelectasis
- perfused, not ventilated - stiffness = stretch work arterial becomes venous - high FiO2 requirement - PEEP requirement: barotrauma |
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ARDS tx
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Rx underlying cause
minimize O2 consumption - fully ventilate them - Rx fever, pain, anxiety - sedate - neuromusclar blockade (rarely) recruit alveoli - add positive pressure (PEEP) to open up alveoli |
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what finding best fits with flow work of breathing problem
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wheezing
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53 yo male with 15 r hx severe asthma; FEV1 28% of predicted 2 yo; increase SOB over last wk; barrel chest, minimal sputum; intubated and bagged (by hand) in ER; hypotensive since intubation; acute on chronic respiratory acidosis; wide gradient
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grossly abnormal lung function
COPD acute worsening hyperinflation with air trapping on radiograph high work of breathing - lung problem - air trapping worsened by positive pressure ventilation ** Flow work |
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high work of breathing Ddx
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flow work
- upper airway - lower airway: COPD (bronchospasm moderate, bronchitis, emphysema moderate) & asthma stretch work volume work |
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flow work problem tx
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permit more time for exhalation
- increase expiratory time = decrease ventilator RR = decrease ventilator tidal volume = increase inspiratory flow rate prevent airway closure - continuous positive airway P : CPAP drugs |
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tx drugs for flow work problem
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bronchodilators: B agonists
anti inflammatories: steroids sedatives: benzodiazepines neuromuscular blockers |
