ARDS and ALI Flashcards by A B

Define hypoxemic respiratory failure

Causes?

anything that limits diffusion or V/Q matching so O2 sat decr diffusion across alveolocapillary membrane (impaired gas diffusion)
–> V/Q mismatch

-> high altitude (low PIO2)
-> alveolar hypoventilation

How well did you know this?

Not at all

Perfectly

What is alveolar hypoventilation

excess CO2

No room for O2

How well did you know this?

Not at all

Perfectly

What are examples of V/Q mismatch diseases

1) pneumonia
2) pulm edema
3) obstructive airways

How well did you know this?

Not at all

Perfectly

which conditions are more likely to have signif shunt

1) alveolar collapse or filling

PNA/ARDS

How well did you know this?

Not at all

Perfectly

examples of decr diffusion across alveolocapillary membrane causing hypoxemia

1) interstitial fibrosis

2) amyloid

How well did you know this?

Not at all

Perfectly

examples of alvolear hypoventilation causing hypoxemia

1) sedatives
2) alcohol
3) brain injury
4) neuromuscular disease

How well did you know this?

Not at all

Perfectly

define hypercapneic resp failure

separated by?

any process that impairs ventilation (CO2 elimination) or elev CO2

can’t breathe vs. won’t breathe

How well did you know this?

Not at all

Perfectly

hypercapneic resp failure

if you can’t breathe, causes…

lung diseases

1) asthma
2) COPD
3) upper airway obstruction
4) severe burn (chest wall restriction)
5) trauma
6) neuromuscular

How well did you know this?

Not at all

Perfectly

hypercapneic resp failure

if you won’t breathe, causes

chronic lung disease
adapted to chronic ability to hypoventilate

1) central hypoventilation
2) oversedation
3) brain injury
4) seizure

How well did you know this?

Not at all

Perfectly

2 determinants of ventilation

To incr ventilation, incr…

1) tidal volume (affects ventilation)

2) respiratory rate (affects ventilation)

How well did you know this?

Not at all

Perfectly

To incr oxygenation on ventilation

3) incr FIO2 (0.21 vs. 1.00)

4) PEEP (more recruit alveolus)

How well did you know this?

Not at all

Perfectly

what ultimately determines PaCO2

alveolar ventilation

Va = (Vt - Vd) x f

How well did you know this?

Not at all

Perfectly

Define dead space ventilation

causes of deadspace

a process that decr perfusion to ventilated alveoli, incr physio dead space (air, but no blood flow)

1) hypovolemia (lower perfusing pressure –> alveolar collapse and need high vent pressures)
2) decr CO
3) PE (stopped blood flow)
4) high airway pressures (when alveolar pressure > capillary pressure = no ventilation = zone 1)

How well did you know this?

Not at all

Perfectly

When evaluating respiratory failure,

procedure?

1) physical exam
2) CXR
3) ABG

How well did you know this?

Not at all

Perfectly

Standard notation of ABG

pH/pCO2/pO2

How well did you know this?

Not at all

Perfectly

Calculate A-a DO2

7.36/36/65 on room air in Denver

PAO2=(Pbar-PH2O) x FIO2-PaCO2/RQ
PAO2=(630-47)x 0.21-36/0.8
PAO2=77

A-a DO2= PAO2-PaO2
A-a DO2= 77-65
A-a DO2= 12

How well did you know this?

Not at all

Perfectly

Normal A-a reflects ___

normal lung function in regards to oxygenation

How well did you know this?

Not at all

Perfectly

Hypoxemia in setting of normal A-a DO2 is due to?

Low Pbar
Low FIO2
Low PaCO2

How well did you know this?

Not at all

Perfectly

Compensation rules for acute respiratory acidosis

[HCO3-] ↑ 1 mEq/L : PaCO2 ↑ 10 mm Hg

∆ pH = 0.008 x (40- PaCO2)

How well did you know this?

Not at all

Perfectly

Comepnsation rules for chronic respiratory acidosis

Study These Flashcards

[HCO3-] ↑ 4 mEq/L : PaCO2 ↑ 10 mm Hg

∆ pH = 0.003 x (40- PaCO2)

Approach to classification of respiratory failure

Study These Flashcards

1) calculate A-a DO2 to classify hypoxemia
- primary diffusion, V/Q or shunt
- hypercapnea

2) acute vs. chronic based on clinical
3) if respiratory acidosis is present, THERE IS A COMPONENT OF hypercapneic resp failure
4) determine acute vs chronic based on compensation rule

KNOW!!!!!!!!!!
for the exam,
if a patient has hypoxemic due to alveolar hypoventilation, THEY HAVE ____

Study These Flashcards

they don’t have hypoxemic respiratory failure

THEY HAVE HYPERCAPNIC RESPIRATORY FAILURE

normal A-a gradient excludes ____

Study These Flashcards

hypoxemic respiratory failure

Example 1
65 year old woman with mild emphysema, no home oxygen requirement, and 3 days of increasing cough and wheeze presents with shortness of breath.
ABG: 7.28/55/30 on room air.

Calculate A-a on room air in Denver

Study These Flashcards

PAO2=(Pbar-PH2O) x FIO2-PaCO2/RQ
PAO2=(630-47)x 0.21-55/0.8
PAO2= 54

A-a DO2= PAO2-PaO2
A-a DO2= 54-30
A-a DO2= 24

∆pH = 0.12 (from 7.40)
∆pCO2=15 (from 40 normal)
0.12/15=0.008 (and ratio = 0.008) so pure acute mixed resp failure resp acidosis
(both acute hypoxemic and hypercapneic)

Example 1 65 year old woman with mild emphysema, no home oxygen requirement, and 3 days of increasing cough and wheeze presents with shortness of breath. ABG: 7.28/55/30 on room air. Diagnosis?

∆pH = 0.12 (from 7.40) ∆pCO2=15 (from 40 normal) 0.12/15=0.008 respiratory acidosis hypercapneic resp failure hypoxemia we know she has hx of emphysema and she has no home O2 so likely just ACUTE

Long-term smoker who hasn’t seen a doctor in 40 years comes in with obvious emphysema on Xray, saturating 82% on room air, 92% on 4L?

has some chronic hypoxemia feeling fine —> then came down with cold (acute on chronic)

Example 2 42 y/o morbid obesity and chronic low back pain. Has had worsened low back pain the past few days, for which he has been taking oxycodone. Brought into ED after family found him very sleepy and confused. ABG: 7.30/54/55 on room air. Calculate the A-a DO2: on room air in Denver

PAO2=(Pbar-PH2O) x FIO2-PaCO2/RQ PAO2=(630-47)x 0.21-55/0.8 PAO2= 55 A-a DO2= PAO2-PaO2 A-a DO2= 55-55 A-a DO2= 0 ∆pH = 0.09 ∆pCO2=14 0.09/15=0.006 (between 0.003 and 0.008 since between acute and chronic = acute-on-chronic)

∆pH = 0.09 ∆pCO2=14 0.09/14=0.006 no hypoxemic acute-on-chronic hypercapnea PaCO2 is high, pH low

Patient with chronic lung disease on 2L per minute nasal cannula O2 at home comes in with sat of 92% on 2L? comes in with saturation of 82% on 2L, 92% on 6L

chronic hypoxemic at basleine acute on chronic resp failure (when there is change in baseline and have chronic so manage the chronic)

Define PEEP

ET tube prevents glottis' ability to maintain expiratory pressure and lung inflation when vent goes into exhalation, provides an adjustable back pressure to stim glottic closure --> MAINTAIN ALVEOLAR RECRUITMENT AND SURFACE AREA, PREVENT DERECRUITMENT

Without PEEP what happens?

1) atelectasis = deflation of alveoli causing alveolar de-recruitment, decr surface area PEEP maintains surface area in hypoxemia

100% FIO2 AND 5 PEEP | and not oxygenating well then ____

turn up the PEEP

22 year old woman with history of asthma comes in with an acute attack, requiring intubation and mechanical ventilation. What type of respiratory failure do you expect? 7.10/80/470

PAO2=(Pbar-PH2O) x FIO2-PaCO2/RQ PAO2=(630-47)x 1-80/0.8 PAO2= 483 A-a DO2= PAO2-PaO2 A-a DO2= 483-470 A-a DO2= 13 ∆pH = 0.3 ∆pCO2=40 0.3/40=0.008 ACUTE HYPERCAPNEIC RESP FAILURE need to incr ventilation

22 year old woman with history of asthma comes in with an acute attack, requiring intubation and mechanical ventilation. Assuming her vent settings are VT 500, RR 20, FIO2 100%, PEEP 5, what next?

HYPERCAPNEIC RESP FAILURE need to incr ventilation ``` Decrease FIO2 increase RR (or VT), ``` turn down FIO2 because 470 is too high and don't have to worry about oxygenation treat asthma with standard therapies (steroids, bronchodilators, ± antibiotics).

62 year old woman with history of chronic systolic heart failure comes in decompensated and volume overloaded. Despite diuresis, afterload reduction, and supplemental oxygen, she requires intubation and mechanical ventilation. What type of respiratory failure do you expect? 7.50/28/45

PAO2=(Pbar-PH2O) x FIO2-PaCO2/RQ PAO2=(630-47)x 1-28/0.8 PAO2= 578 A-a DO2= PAO2-PaO2 A-a DO2= 578-45 A-a DO2= 533 ∆pH = 0.10 ∆pCO2=12 0.10/12=0.008 hyperventilating and hypoxemic respiratory fialure acute resp alkalosis pulm edema interstitial and alveolar space --> hypoxemia

62 year old woman with history of chronic systolic heart failure comes in decompensated and volume overloaded. Despite diuresis, afterload reduction, and supplemental oxygen, she requires intubation and mechanical ventilation. Assuming her vent settings are VT 500, RR 20, FIO2 100%, PEEP 5, what next?

Ventilation is OK. Since our vents don’t go to 11, our only option is to increase PEEP. since vent already maxed out at FIO2 = 100% can only change PEEP

Definition of ARDS

occurs within 1 week of known insult/worsening resp symptoms 2) diffuse bilateral pulm infiltrates 3) not explained by cardiac failure/fluid overload 4) severity classfiied by PaO2: FIO2 with > 5 cM-H2O PEEP best if 201-300 = mild

ARDS pathogenesis

1) inflamm and macrophage infiltrate --> disrupt alveolar/capill barrier function --> alveolar flooding with fluid, red cells neutrophils, LOSS surfactant

histology of ARDS

hyaline membrane with hypoxemic resp failure 1) alveolar filling with protein edema 2) denuded basement membrane 3) HYALINE MEMBRANE (PROTEIN DEPOSITION) 4) neutrophils, hemorrhage 5) type II hyperplasia

radiology of ARDS

bilateral alveolar infiltrates

etiology of ARDS

1) Sepsis 2) pancreatitis 3) trauma 4) aspiration 5) transfusion = indirect

most likely pathogenesis of ARDS

UTI --> cytokines --> lungs --> oxidant damage humoral cytokines activ neutrophils

functional disability after ARDS 5 yrs later

at 1 yr --> physiologic limitation over 5 yrs physiology unchanged but return to work improved

how to treat ARDS

1) treat underlying cause 2) supportive care 3) ventilator management 6 cc/kg tidal voluem, plateau pressure

what is ventilator induced lung injury

high tidal volume ventilation can worsen lung injury and systemic inflamm

why is prone position better for ARDS ventilation when to use?

more uniform transpulmonary pressure and distrib of alveolar stress PaO2:FIO2

Before incr a patient's tidal volume based on ABG, ___

make sure does not meet criteria for ARDS

ventilate patient with ___ ON EXAM!!!

LOW TIDAL VOLUME | CONSIDER PRONE IN SEVERE

ARDS and ALI Flashcards

(48 cards)