Respiratory Failure + ARDS Flashcards
Acute respiratory failure
- hypoxic failure
- hypercarbic failure (elimination failure)
- cardiogenic pulmonary edema
- non-cardiogenic pulmonary edema (ARDS)
- pneumonia
Hypoxemia
90%
Decrease in night vision
High altitude pulm edema
Hypoxemia 80-89%
Drowsiness
Poor judgement
Impaired: coordination + efficiency
Hypoxemia
79-70%
Impaired:
- handwriting
- Speech
- vision
- memory
- judgement
- intellect
- sensation to pain
Hypoxemia
<69%
- circulatory failure
- CNS failure
- convulsions
- cardio collapse
- death
When do we need supplemental O2?
<88% or lower sitting (medicare)
Do 6 minute walk test
Alveolar air equation
PO2=FiO2 x (Pb-Pwater)-PaCO2/0.8
Alveolar-Arterial O2 gradient
Alveolar PO2 - arterial PO2
Normal = 1/2-1/3 age
Abnormal>30mmHg
PO2 =
IN AIR = Percentage of air x 760mmHg
IN VOCAL CORDS = percentage of air x (760-47)mmHg
in ALVEOLI = PO2 - PaCO2/0.8
What regulatory mechanism happens in high altitude =
Hyperventilation
CHF = cardiogenic pulm edema
ARDS = non-cardiogenic pulm edema
Path
Not understood how endothelial membrane damaged
- neutro/macro enters
- plasma gets in
- exudate
Acute phase
Path
Intra-alveolar red cells + neutrophils
Fibrosing-Alveolitis Phase
- granulation tissue in the distal air spaces w/ a chronic inflammatory-cell infiltrate
- collagen deposition
ARDS. Risk factors
Pneumonia
Extrapulmonary sepsis
Aspiration
ARDS
Ventilate with High or Low tidal volume?
LOW tidal volume (<6ml/kg) = higher survival
High PEEP or low PEEP
No difference, just keep low tidal volume
ARDS
Tx
Positive pressure mechanical ventilation
- low volume (6mL/kg)
- mode ventilation = doesn’t matter
- use PEEP
Lung protective strategy
ventilation (peep vs. volume)
Under inflection point = Peep keeps higher
Over inflection point = lower tidal volume
PEEP purpose
Makes sure that alveoli doesn’t close when expire
Recruitment?
ARDS tx
Positive pressure
CONSERVATIVE fluid management
NO Rx helps (methypredisolone can increase death risk)
Prone positioning (fluid is gravity dependent, opening new areas)
Extra Corporeal Membrane Oxygenation (ECMO)
ARDS
Path
Proinflammatory cytokines –>diffuse alveolar damage –> alveolar-capillary permeability –> pulmonary edema/alveolar fluid –> hypoxemia
- MC critically ill patients
- acute hypoxemia
- Hours to days after inciting event (ex. sepsis)
- CXR : BILAT INFILTRATES, WHITE-OUT, NO in costophrenic angles
- NO CHF pulm edema
- ABG: PaO2/FIO2 <200mmHg OR <5cmH2O = PEEP!
- PCWP<18mmHG = pulm artery catheterization (opposite CHF!!)
Acute Respiratory Distress Syndrome ARDS
- hypocapnea
- Central neurogenic
- sustained, rapid, deep breaths
- acute: paresthesias, tetany, anxiety
- chronic: fatigue, anxiety, palpitations (s/s reproduced if voluntary action)
Hyperventilation Syndrome
Hyperventilation Syndrome
Tx
breathing through pursed lips/1 nostril/paper bag
*Rx: anti-anxiety
Respiratory failure
- PaO2 <60mmHg
- PaCO2 = normal/down
HYPOXEMIC
Type 1 RF
*Alveoli block, Poor alveoli gas transfer, obstructed blood flow
Respiratory failure
*PaCO2 >45mmHg
HYPERCAPNIC
Type 2 RF
*decreased alveolar minute ventilation
Tx: O2
Respiratory failure
- abnormal chest wall mechanics - surgery/trauma
- splinting
PERIOPERATIVE
Type 3 RF
- regional atelectasis
- hypoventilation
Respiratory failure
- normal lungs
- increased ventilatory demands from hypermetabolism (sepsis)
HIGH-DEMAND
Type 4 RF
*muscle fatigue? –>ventilation
CXR - cardiogenic Pulm Eedema or not?
- Heart size: enlarged
- Edema : central
- Pleural effusions, peribronchial cuffing, septal lines
- NO air bronchiograms
Cardiogenic
CXR - Cardiogenic Pulm Edema or Not?
- heart size: normal
- edema: patchy/peripheral
- NO pleural effusions, peribronchial cuffing, septal lines
- YES air bronchograms
Non-cardiogenic pulm edema
PO2/FIO2 ratios
- normal
- ARDS mild
- ARDS Moderate
- ARDS Severe
- Normal = 429 mmHg
- ARDS mild = 300 mmHg
- ARDS moderate = 150 mmHg
- ARDS severe = 90 mmHg
