Respiratory Failure and Mechanical Ventilation

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Respiratory Failure and Mechanical Ventilation

• P. Vorrakitpokatorn

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Respiratory Function
Maintain Adequate Oxygenation and Ventilation
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Respiratory Failure

• Definition Inability to maintain
• Oxygenation
• Ventilation(pump)

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Dx RESPIRATORY FAILURE
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???????????????????? of Respiratory failure

• Stimulation and then depression

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???????????????????? of Respiratory failure
CNS ??????????? ???
CVS ????????? ????????????? ???????
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??????????????? ????????? ??????????????

• ????????????.

?????????? ???????????????????
??? ????? ???? ?? hypoxemia ??????? ???? long
capillary refill ?? hypercarbia Tripod position

• ??????????????.

????????????????????????????? Respiratory
paradox
????????????? rapid shallow breathing
??????? (gt 30, lt 8 ?????/????)

• ?????????????

• ???

Upper airway inspiratory stridor Lower
airway expiratory wheez
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Central cyanosis hypoxemia
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Hypercarbia vasodilatation,warm moist slow
capillary refilledgt 3 seconds
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The tripod sign used to describe the classic
position of a person desperate for more air
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Tripod position (5) is a red flag indicating
severe inflammation and impending upper airway
obstruction. The tripod sign is a term used to
describe the classic position of a person
desperate for more air the patient leans
forward on outstretched arms to open the airway
by moving the inflamed and swollen epiglottic
structures forward. This position tends to ease
the patient's upper airway obstruction and
relieves the choking sensation, which is
aggravated by sitting back or lying flat.
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RESPIRATORY FAILURE Classification

• Type 1. Oxygenation failure
• type 2. Ventilatory failure
• and mixed type

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?????? hypoxemia

• (A-a)O2 normal
• ?????????????????????????????????????????

(A-a)O2 Increase ???????????????????????????????
????????????????
Diffusion defect V/Q mismatch True
shunt Delivery?demand

• Decrease FiO2
• CO2 retention

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Alveolar Air Equation

• PAO2 FiO2 (PB-PH2O) - PAO2/ R

R 0.8 FiO2 lt 0.6 R 1.0 FiO2 0.6
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?????? Oxygenation failure A. normal (A-a)O2,
PaO2
PaO2
PaO2
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?????? Oxygenation failure B. high (A-a)O2
PaO2
PaO2
PaO2
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??? MV-O2 ??????? PaO2 ????????????? ????????
decrease CO Increase used
PAO2
PCO2 100 ...
Tissue O2 DEMAND organs
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(A-a)O2 20 at room air (A-a)O2 100 at FIO1
Hypoxemia (A-a)O2?

• How much PaCO2?
• How much FIO2?

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Hypoxemia differential diagnosis
MV-O2 ???? resp system

• Gas exchange abnormal
• Diffusion
• V/Q
• shunt

Hypoxemia (A-a)O2
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Hypoxemia (A-a)O2??? PV-O2 ???? Gas exchange
abnormal

• Diffusion defect
• V/Q mismatch

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• response to oxygen
• therapy
• Worse if inadequate
• time to exchange
• as tachycardia

Diffusion defect
second
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?????????????? CO2 ????
VA Effective alveolar ventilation
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Pa CO2 CO2 production /effective ventilation
CO2
Tissue metabolism
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Effective Tidal volume Breath
VT Vd Alv ventilation
Vd ventilate but not perfuse
?????????????????????????????????????????
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Deadspace ventilation and CO2 retention
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Ineffective alveolar ventilation too large
dead space
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Dead space
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Hypercarbia differential diagnosis
Hypercarbia ( A-a)O2

• MV ????????
• Ineffective ventilation (airway obstruction,vd)
• ?????????????????
• CO2 contamination

• MV???? CNS or neuromuscular
• Depress rc PIMax ??????
• Pump abn PIMax ???

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Obstructive sleep apnea
Airway obstruction
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Hypercarbia differential diagnosis
Hypercarbia ( A-a)O2

• MV ????????
• Ineffective ventilation (airway obstruction,vd)
• ?????????????????
• CO2 contamination

• MV???? CNS or neuromuscular
• Depress rc PIMax ??????
• Pump abn PIMax ???

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??????????????????????????????????

• ?????????????
• ??????????????????????CO2 ????
• ?????????????? ??????????????
• ?????????????
• ????????????????????
• ??????????????????????????????????? CARDIAC ARREST

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??????????????????????????????????
1. Inadequate oxygenation
??????????????????????????? ??? ??????????????
????????????????????????????? ????????????????????
???????????
PARAMETERS NORMAL IPPV
needed PaO2/FiO2 PaO2/FiO2 350-450
PaO2/FiO2 lt 200
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Severity of Oxygen impair
PaO2 / FiO2 ?
????????? ??????????????????? ??????????????
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Severity of gas exchange defect PaO2/FiO2
PaO2/FiO2gt200 shunt lt20
Spontaneous resp_increase FiO2
PaO2/FiO2 150-200 shunt gt20 Need IPPV
especially in CVS,CNS patients
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2. Inadequate Ventilation
PARAMETERS NORMAL IPPV
needed PaCO2 40 50 pH
7.4
7.3 ????????????? ?????/???? 12-24
lt 8, gt30
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??????????????????????????????????
3. Inadequate lung expansion ????????????????

PARAMETERS NORMAL IPPV VT
??/?? 6-8 lt5 Vital
Capacity ??/?? 65-75 lt 10

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??????????????????????????????????
4. Inadequate muscle power ?????????????
PARAMETERS NORMAL IPPV
needed
Max negative pressure -80-(-120)
gt (-25) ??.??? Vital Capacity ??/??
65-75 lt 10 MVV
????/???? 120 lt 20 ??????????????
normal paradox

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??????????????????????????????????
5. ????????????????????
PARAMETERS NORMAL IPPV
needed Minute Ventilation ???? 6-8
gt 10 ????????????? (?????/????) 12-20
gt 30-35 ?????????????? ???????? accessory
muscle
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???????????????????????????????? oxygen
supplement

• Mild oxygenation,ventilation,mechanic failure
• RC intact
• Vtgt5,lt15 ml/kg
• respiratory rate gt8,lt30

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????????????????????????????????

• CNS.. ?????????????????????? ????????????????????
• CVS. ?? venous return ?????????
• RS. ????? oxygenation,ventilation,
• barotrauma
• Renal. ?? urine out-put ?????????????? ADH
• GI.. Abdomen distention,stress ulcer
• Psychic trauma
• Infection