Pathophysiology Of Acute Respiratory Failure

Front 1

what primary or secondary disorders of what areas can lead to ARF? (4)

Back 1

1.airways
2.lung parenchyma
3.chest wall
4.neural processes

Front 2

important facotr in development of ARF?

Back 2

fatigue of muscles of breathing

Front 3

how is ARF distinguished from CRF?

Back 3

ARF - abrupt increase of PaCO2 and decreases of pH

CRF - pH 7.35-7.45 despite increased PaCO2

Front 4

what happens to the following in ARF?

a.PaO2
b.PaCO2
c.pH
d.RR

Back 4

a.PaO2 = <70mmHg on 50% O2
b.PaCO2 = >50-55mmHg (can also be decreased or not changed)
c.pH = <7.3
d.RR = >35breaths/min (tachypnea)

Front 5

what happens to the following in ARF?

e.vital capacity
f.inspiratory force
g.FRC
h.lung compliance
i.PAPW
h.pulmonary vascular resist

Back 5

e.vital capacity = <15mL/kg
f.inspir force = <25cmH2O
g.FRC = decreased
h.lung compliance = decreased
i.PAPW = <15mmHg despite pulm edema
h.pulmonary vascular resist = increased w/ pulm HTN

Front 6

in ARF, PaO2 is low despite what 2 things?

Back 6

1.supplemental O2
2.absence of rt to lft intracardiac shunt

Front 7

in ARF, name 3 causes of low PaO2

Back 7

1.v/q mismatching
2.rt to lft pulmonary shunting
3.alveolar hypoventilation

Front 8

what influences whether CO2 changes in ARF?

Back 8

relation of alveolar ventilation to metabolic produciton of CO2

Front 9

when PaCO2 in increased, how do you know if hypoxemia is due to hypoventilation or a combination of hypoventilation and v/q mismatching?

Back 9

by calculating the A-a gradient (PAO2-PaO2)

Front 10

how do you calculate PAO2?

Back 10

PAO2 = (%FiO2x713)-PaCO2/0.8

Front 11

where do the 713 come from in PAo2 equation?

Back 11

barometric pressure at sea level 760 - water vapor pressure 47 = 713

Front 12

some causes of hypoventilation?

Back 12

1.resp muscle wkness
2.decreased vent drive

Front 13

cause of v/q mismatch?

Back 13

COPD

Front 14

when A-a gradient is normal, arterial hypoxemia is due to ? what is normal A-a gradient?

Back 14

pure hypoventilation

no more than 15mnmHg

Front 15

when A-a gradient is increased, arterial hypoxemia is due to?

Back 15

v/q mismatching and/or right-to-left intrapulmonary shunting

> 15mmHg

Front 16

what is the compensatory mechanism that creates a normal pH with elevated PaCO2 in chronic resp failure?

Back 16

renal tubular reabsorption of bicarbonate

Front 17

acute respiratory distress syndrome (ARDS)

Back 17

arterial hypoxemia associated w/ acute lung injury

Front 18

what lung injury characterizeds ARDS?

Back 18

1.diffuse alveolar damage (influx of protein rich edema fluid into alveoli due to increased permeability of alveolar capillary membranes)

2.noncardiogenic pulmonary edema

Front 19

what prevents adeq gas exchange in ARDS?

Back 19

fluid filled alveoli

Front 20

what is normal gas exhange in the lungs?

Back 20

exchange of gases across alveolar walls allowing uptake of fresh O2 and relaease of CO2

Front 21

name some direct causes of ARDS (5)

Back 21

1.aspiration (gastric contents, fresh/salt water, hydrocarbon fluids)
2.lung contusion
3.pneumonia (viral, bacterial, TB, fungal, pnuemonocyctis carinii)
4.fat, air, amniotic fluid emboli
5.inhalational injury (smoke, high concent of O2, corrosive chemicals)

Front 22

name some indirect causes of ARDS (8)

Back 22

1.sepsis
2.nonthoracic trauma
3.drugs (heroin, methadone, propoxyphene, barbs, colchicine, asa, hztz)
4.shock (hematologic DO, massive blood transfusion, DIC, cardiopulmonary bypass)
5.metabolism (acute pancreatitis, uremia)
6.increased ICP
7.ascent to high altitudes
8.eclampsia

Front 23

S&S of ARDS (5)

Back 23

1.arterial hypoxemia resistant to treatment w/ supplemental O2
2.CXR that look like cardiogenic pulmonary edema
3.fibrosing alveolitis
4.pulmonary HTN progressing to rt side heart failure
5.pneumothorax

Front 24

characters of fibrosing alveolitis

Back 24

1.persistant arterial hypoxemia
2.increased alv deadspace
3.further dec in pulm compliance

Front 25

when do survivors of ARDS regain normal lung fxn?

Back 25

6-12 months

Front 26

3 principle treatment goals for ARF?

Back 26

1.correct arterial hypoxemia
2.remove excess CO2
3.provide patent upper airway

Front 27

ways to correct arterial hypoxemai in ARF?

Back 27

1.maintain pao2 60-80

2.spontaneously breathing patients: supplmental O2 via n/c, venturi mask, nonrebreathing mask, or T-piece (attached to free end of tracheal tube)

3.continuous positive airway pressure w/BIPAP or CPAP to open previously closed alveoli

4.ETT w/ mechanical vent if previous interventions do not work

Front 28

what is the disadvantage of n/c, venturi mask, nonrebreathing mask, or T-piece?

Back 28

seldom provide inspired oxygen concentrations higher than 50% in severe ARF

Front 29

what is the disadvantage of high concentrations of O2?

Back 29

toxic to lungs b/c
1.excessive production of free O2 radicals
2.replacing all nitrogen w/ O2 removes the "nitrogen splint" which leads to collapse of alveoli and absorption atelectasis

Front 30

non-resp way to facilitate the removal of excessive carbon dioxide

Back 30

increasing CO by
1.optimizing IV fluid
2.positive inotropes

Front 31

when is it necessary to provide tracheal intubation w/ mechanical ventilation in ARF patients?

Back 31

if PaO2 cannot be maintained at 60mmHg with 50% oxygen

Front 32

2 modes of ventilation

Back 32

1.volume-cycled ventilation
2.pressure-cycled ventilation

Front 33

what are the subclasses of volume-cycled ventilation?

Back 33

a.assist-control ventilation (AC)

b.synchronized intermittent mandatory ventilation (SIMV)

c.postitive end-expiratory pressure (PEEP)

Front 34

3 characteristics of assist-control ventilation (AC)

Back 34

1.patient initiates breath
2.breath delivered at preset Vt
3.set rate of Vt breaths

Front 35

synchronized intermittent mandatory ventilation (SIMV)

Back 35

1.patient initiates breath
2.patient initiates Vt
3.certain minute ventilation delivered from ventilator

Front 36

postitive end-expiratory pressure (PEEP)

Back 36

allows positive pressure throughout resp cycle

Front 37

when is postitive end-expiratory pressure (PEEP) beneficial?

Back 37

when exhalation is incomplete during airway obstruction

Front 38

what population are pressure cycled ventilation typically used?

Back 38

children

Front 39

what 3 classes of drugs may be used to help manage patients receiving mechanical ventiliation?

Back 39

1.sedatives
2.analgesics
3.paralytics

Front 40

what sedatives may be used during mech ventilation? what are their benefit?

Back 40

a.benzodiazepines
b.propfol
c.remifentanil

prevent self extubation, barotrauma, and excessive deterioration in gas exchange

Front 41

why are propofol and remifentanil good choices for mech vent support?

Back 41

disappears fast so can cut off to do neuro assessments and can be weaned off quick

Front 42

when are paralytics good for mech ventilated patients? what should be considered in regard to clearance of NMBAs?

Back 42

if sedation is inadeq or hemodynamic instability is present

dependenc of certain NMBAs on renal clearence (pancuronium, vercuronium, rocuronium) should be considered

Front 43

risk associated with paralytic use?

Back 43

prolonged durg-induced paralysis in diffuse polyneuropahtys that may accompnay critical illnesses

Front 44

what analgesics may be used during mech vent management?

Back 44

opioids

Front 45

complications of ET intubation and mechanical ventilation (5)

Back 45

1.infection
2.alveolar overdistension
3.barotrauma
4.atelectasis
5.critical illness myopathy

Front 46

name of infection associated w/ ETT & mech vent.

Back 46

ventilator-associated pneumonia

Front 47

prevention of alveolar overdistension

Back 47

1.smaller Vt 5-8ml/kg
2.airway pressure no more than 30

Front 48

ABG effect of alveolar overdistension

Back 48

hypercapnia

Front 49

2 effects of barotrauma

Back 49

tension pneumothorax
arterial gas embolism

Front 50

most common cause of arterial hypoxemia secondary to mech vent?

Back 50

atelectasis

Front 51

treatment of atelectasis

Back 51

bronchoscopy to remove mucus plugs

Front 52

what is critical illness myopathy?

Back 52

neuromuscular weakness that persists long after resp failure is resolved

Front 53

what can critical illness myopathy reflect?

Back 53

axonal disorder occuring w/ sepsis and multiple system organ failure

Front 54

what can accentuate critical illness myopathy?

Back 54

NMBAs

Front 55

to dc mechan vent where should the following measurable factors be:

a.gas exchange
b.vital capacity
c.PaO2
d.max insp pressure
e.pH
f.RR
g.Vd/Vt
h.condiser coexist abnorm

Back 55

a.gas exchange: maintain PaO2 and eliminate CO2
b.vital capacity >15ml/kg
c.PaO2 >60mmHg on <50% O2
d.max insp pressure >-20cmH2O
e.pH = normal
f.RR <20 breaths/min
g.Vd/Vt ration < 0.6
h.consider coexist abnorm: anemia, hypokalemia, hypovolemia

Front 56

to dc mechan vent subjective factors should be present?

Back 56

1.alert
2.cooperative
3.tolerate sponteneous vent w/o tachypnea, tachycardia, or distress
4.active laryngeal reflexes (cough, clear secretions, glottic fxn not impaired)

Front 57

methods used to withdraw mechanical vent and benefit of each.

Back 57

1.SIMV (allows spontan breathing & diminished mandatory breaths per min until pt is breathing completely spont)
2.T-piece (intermittent trials & total removal from mech vent while breathing spont)
3.decreasing levels of pressure-support vent

Front 58

with method used to withdraw mech vent is least effective?

Back 58

decreasing levels of pressure-support vent

Front 59

signs that COPD is acutely deteriorating to ARF (4)

Back 59

1.increased dyspnea
2.altered consciousness
3.retention of secretions
4.further deterioration of gas exchange

Front 60

how can vicious cycle of COPD progressing to ARF be prevented? give examples.

Back 60

by treating triggering events
--pneumonia
--CHF
--increased production of CO2 by fever

Front 61

treatment goals for COPD exacerbations (7)

Back 61

1.analyze ABGs
2.maintain pao2 at least 50-60
3.accept PaCO2 changes as long as pH >7.2
4.bronchopulmonary lavage
5.encourage coughing
6.meds: antibiotics, bronchodilators, corticosteroids
7.mechan vent

Front 62

when would you use noninvasive vent methods to treat COPD exacerabations? what would you use?

Back 62

alert despite hypercarbia

BIPAP via tight fitting face mask

Front 63

what is benefit of noninvasive vent methods?

Back 63

decreased risk of nosocomial infection

Front 64

what pressures do BIPAPs deliver?

Back 64

ins pressure 15-20 cmH2O
exp pressure 3-5 cmH2O

Front 65

when would you use tracheal intubation to treat COPD exacerabations?

Back 65

1.hemodynamically unstable
2.somnolent
3.secretions can't be cleared

Front 66

what is the disadvantage of tracheal intubation?

Back 66

risk of nosocomial infections

Front 67

which indirect lung injury is associated with highest risk of progression to ARDS?

Back 67

sepsis

Front 68

death associated with ARF in pts with acute lung injury and ARDS is most often attributed to ____ or ____ rather than primary resp causes

Back 68

sepsis or multi-organ failure

Front 69

treatment of ARF associated with acute lung injury and ARDS (7)

Back 69

1.search for underlying cuase
2.prevent: further infection, GI bleeding, thromboembolism
3.adeq nutrition
4.ventilation via trachal intubations w/ mech vent & inverse-ratio ventilation
5.fluid & hemodynamic mgmt
6.drugs: diuretics, corticosteroids
7.removal of secretions

Front 70

in ARF associated with acute lung injury and ARDS:

ways of preventing further infection

Back 70

proper respiratory
oral care
keep et cuff inflated

Front 71

in ARF associated with acute lung injury and ARDS:

which method of nutritional support is preferred? why?

Back 71

enteral feeding
no risk of catheter sepsis

Front 72

in ARF associated with acute lung injury and ARDS:

how can you minimize barotrauma?

Back 72

PaO2 60-80 using Vt 8-10ml/kg

Front 73

disadvantage of excessive levels of PEEP

Back 73

1.overdistended alveoli
2.compressed capillaries
3.decreased VR
4.decreases CO
5.decreased PaO2 (b/c blood is shunted away from full alveoli)

Front 74

advantages and disadvantages of inverse-ratio vent

Back 74

advantages
1.insp time exceeds exhalation time
2.may improve arterial oxygenation w/out PEEP

disavantage
1.barotrauma
2.hypotension d/t auto PEEP

Front 75

what are the signs of adeq organ perfusion adn CO?

Back 75

1.metabolic acid/base balance
2.adeq renal fxn (UOP 0.5-1 ml/kg/hr)

Front 76

what pulm artery occlusion pressure reflects inadeq IV fluid volume?

Back 76

< 15

Front 77

how can you improve secretion removal?

Back 77

1.adeq systemic and humidification of inspired gases
2.fiberoptic bronchoscopy

Front 78

compensatory responses to arterial hypoxemia

Back 78

1.increased alveolar ventilation (from carotid body stimulation)
2.regional pulmonary artery vasocon (to divert blood flow from hypoxic alveoli)
3.increases SNS activity (to enhance tissue O2 delivery by increased CO)

Front 79

significant desaturation occurs once PaO2 decreases to below what?

Back 79

< 60

Front 80

at what PaO2 do compensatory mechanisms fail? what will occur?

Back 80

PaO2 of 30

cell damage and death

Front 81

what should be monitored during ARF treatment?

Back 81

1.pulmonary gas exchange
a.O2 exchanges and PaO2
b.CO2 elimination
c.mixed PvO2
d.arterial pH
e.intrapulmonary shunting

2.cardiac fxn
a.CO
b.cardiac filling pressures
c.intrapulmonary shunt

3.PA catheter

Front 82

what does Vd/Vt ratio reflect?

Back 82

efficacy of CO2 transfer across membrane

Front 83

what is Vd/Vt?

Back 83

dead space volume/tidal volume ratio which depicts lung areas that receive adeq ventilation but inadeq or no pulm blood flow

Front 84

normal Vd/Vt

Back 84

< 0.3

Front 85

what dz processes can Vd/Vt be incrased to 0.6 or more?

Back 85

ARF
decreasead CO
PE

Front 86

what dose mixed PvO2 represent?

Back 86

oxygen transport system: O2 delivered vs amt of O2 taken up by tissues

Front 87

what is intrapulmonary shunting?and what happens to PaO2?

Back 87

perfusion of alveoli not being ventilated

decreases

Front 88

Lung Transplantation
Four approaches.

Back 88

1.Single lung transplant
2.Bilateral lung transplant
3.Heart-lung transplant
4.Transplantation of lobes

Front 89

Name some indications for lung transplant. (4)

Back 89

Any end stage resp failure condition such as:

1.Cystic fibrosis
2.COPD
3.Pulmonary fibrosis
4.Primary pulmonary hypertension

Front 90

why is aseptic technique important in lung transplant pts?

Back 90

immunosuppression

Front 91

monitoring devices & equipment during lung transplantation

Back 91

PA catheter
DLETT
postop mech vent

Front 92

name some pathophysiology issues of patients undergoing lung transplant.

Back 92

1.Pts. will demonstrate restrictive patterns (mild to moderate pulm HTN & some rt sided heart failure)
2.Strict asepsis
3.Arterial hypoxemia with one-lung ventilation
4.Pulm. HTN when PA clamped

Front 93

bad drugs & good drugs for pts undergoing lung tranplant?

Back 93

bad: histamine releasing

good: bronchodilators

Front 94

how to correct Arterial hypoxemia with one-lung ventilation

Back 94

trial of PEEP to dependent lung

Front 95

treatment of pulm HTN during PA clamping in lung transplant surgery

Back 95

1.prostacylcin infusion
2.in extreme cases cardiopulmonary bypass is necessary

Front 96

POSITIVE physiologic effects after Lung Transplantation

Back 96

1.Peak improvement in 3-6 months
2.Arterial oxygenation returns to normal
3.Pulmonary vascular resistance normalizes
4.↑ CO
5.Improved exercise tolerance
6.inhaled b2 agonists produce bronchodilation

Front 97

NEGATIVE physiologic effects after Lung Transplantation

Back 97

Lung denervation (loss of cough reflex, blunted vent response to CO2, and mucociliary clearance impaired)

Front 98

Complications of lung transplantation (7)

Back 98

1.Pulmonary edema
2.Dehiscence of bronchial anastomosis
3.Anastomotic stenosis
4.Infection
5.Acute rejection
6.Chronic rejection - Bronchiolitis obliterans

Front 99

what are the anesthesia considerations when working with a patient who has had a lung transpant?

Back 99

1.Function of transplanted lung
2.Possibility of rejection or infection
3.Effects of immunosuppressive therapy
4.Disease of the native lung
5.Planned surgical procedure and its effects on the lungs

Front 100

Preop. Evaluation of a pt with a Transplantated Lung (4)

Back 100

1.History of increasing dyspnea or need for supplemental oxygen
2.SE of immunosuppressive drugs 3.Chronic rejection
4.Preop. medications

Front 101

when does acute lung transplant reject typically occur?

Back 101

100 days after transplantation

Front 102

what is Bronchiolitis obliterans in relation to
Chronic lung rejection?

Back 102

--fibroproliferative process that targets small airways and leads to submucousal fibrosis and luminal obliteration

--uncommon during first 6 months

--incidence exceeds 60% in pts who survive for 5 years

Front 103

name 2 side effects of immunosuppressive drugs

Back 103

pulm HTN, renal dysfxn

Front 104

what can chronic lung transplant rejection hard to differentiate from?

Back 104

resp infection

Front 105

signs of chronic lung transplant rejection

Back 105

Forced exp vol, vital capacity and TLC will be dec., arteial hypox., inc. A-a gradient, chronic cough may be sign of brochiolitis obliterans

Front 106

what are some preop meds that may be given to lung transplantees that are have surgery? considerations of each?

Back 106

1.opioids (will have inc. sensitivity)
2. supp. corticosteroids (for long stressful operations)
3.prophylactic abx
4.fluid (preload cautiously)

Front 107

best Choice of Anesthetic Technique for Lung Transplantees having surgery?

Back 107

Regional is best
--Decreased cough reflex
--Potential for bronchoconstriction
--Increased risk of aspiration & pulmonary infections

Front 108

anesthesia managemnt, monitoring, and goals of lung transplantees having surgery (3)

Back 108

1.Fluid with caution
2.TEE
3.Prompt recovery and early extubation

Front 109

if you intubate a pt with a lung transplant, what is important to remember?

Back 109

ETT cuff just beyond the vocal cords to prevent tracheal or bronchial anastomosis trauma

Front 110

what 2 things do a TEEs show you?

Back 110

1.cardiac function
2.volume status