Acute Respiratory Failure Lecture Powerpoint Flashcards
Normal A-a gradient value range, higher A-a gradient means what?
10-20, higher means elevated pressure in alveoli than capillaries
Vital capacity + residual volume =
total lung volume
Causes of acute respiratory failure (5)
- decreased FiO2
- Ventilation without perfusion (deadspace ventilation)
- Diffusion abnormality (V/Q ratio affected)
- Perfusion without ventilation (shunting)
- Hypoventilation
Decreased FiO2 causes (2)
- High altitude
- toxic gases
Hypoventilation causes (3)
- COPD
- Neurological disease
- Obstructive sleep apnea
Diffusion abnormality causes (4)
- Interstitial lung diseases
- pneumonia
- ARDS
- Pulmonary edema
More dead space corresponds to ___ work of breathing
Increased
Shunt definition
Blood flow that passes next to alveoli that are collapsed or filled with fluid and inflammation
Physiologic deadspace =
Anatomic dead space + alveolar dead space
Hypercapnia value
Elevated PaCO2 >45mmHg
What causes hypercapnia? (2)
- Decrease in tidal volume
- decrease in respiratory rate
Causes of increased dead space (4)
- COPD/emphysema
- asthma
- cystic fibrosis
- pulmonary fibrosis
Signs and symptoms of hypercapnia are dependent on 2 variables
- level of CO2 in arterial blood
- rate of accumulation
Mild to severe acute hypercapnia signs and symptoms
-anxiety to asterixis (wrist flapping) and delirium
Normal individuals do not exhibit depressed consciousness until PaCO2 >….
75-80mmHg, if chronic will be 90-100
Oxygen associated hypercapnic respiratory failure
Occurs in COPD patients who are used to higher CO2 levels and thus if placed on supplemental O2 will not receive input to breath and worsen with it as a result
If you suspect oxygen associated hypercapnic respiratory failure and O2 at least 95%, ___ supplemental O2
Decrease to 90-93%
Venturi masks provide ___O2 compared to nasal prongs
More
Good candidate for noninvasive positive pressure ventilation has these 5 characteristics
- pH <7.3
- Moderate to severe respiratory distress
- RR >25
- Increased work of breathing
- Must be able to spontaneously breath
CMV ventilation
Set respiratory rate and volume is automated with no patient work, requiring heavy sedation
Assist control
Set minimum respiratory rate and volume, patient may initiate breath but will always be given a set volume (sometimes uncomfortable for patients)
IMV ventilation
Set minimum respiratory rate and volume, spontaneous breaths are volume that patient is able to independently able to achieve
Pressure controlled ventilation
Set inspiratory pressure level, respiratory rate, and PEEP, insiration ends after pressure achieved
Pressure support
Set PS and PEEP, helps patients wean off as they control spontaneous breathing
PEEP
5 is physiologic PEEP, mainstay of adequate oxygenation by preventing collapse of alveoli upon exhalation
PEEP too high consequence
-Blood vessel compression
Noncardiogenic pulmonary edema
Caused by increased capillary permeability most often caused by ARDs and less often HAPE, neurogenic pulmonary edema, opiod overdose, etc.
Acute respiratory disress syndrome
Complication of multiple other diseases resulting systemic response with acute onset of bilateral alveolar infiltrates and hypoxemia, has excess fluid in the interstitium and alveoli and alveoli collapse resulting in dire consequences
Consequences of ARDS (3)
- Decreased lung compliance*** Hallmark sign
- Impaired gas exchange
- pulmonary hypertension
ARDS almost always presents with…
….acute inciting event
Things not seen on an X ray in ARDS
- no caridomegaly
- no pleural effusion
- no kerley B lines
ARDS must have these symptoms to make clinical diagnosis (3)
- respiratory symptoms beginning within 1 week of clinical insult
- unexplained opacities present on cxr or CT
- Moderate to severe impairment of oxygenation even on ventilation
ARDS treatment
Treat underlying condition and supply supportive care for respiratory failure
ARDS prognosis
Depends on funciton of # of organ systems (more important than severity of respiratory failure) and age of patient, generally those who die do so within 2 weeks and if survive need prolonged course of recovery and supportive care
