Respiratory Failure Flashcards
Respiratory failure: physiologic definition is what?
Inability of the lungs to meet the metabolic demands of the body.
A failure of tissue oxygenation and/or CO2 homeostasis
A failure of tissue oxygenation and/or CO2 homeostasis simply put is what?
cant take in enough O2 or eliminate CO2 fast enough
Components of O2 delivery
O2 Deliver (DO2) =?
CO x CaO2
CaO2= ?
(1.34 x Hgb x HgbSat%) + (PaO2 x 0.003)
Oxygen Consumption
VO2 =
Q x (CaO2 x CvO2)
O2 Extraction Ratio
O2ER =
VO2/DO2(normal approx. 25%)
Normal at Sea Level
PIO2 =?
PAO2 =?
PACO2 =?
PAH2O =?
PaVO2 =?
PaO2 =?
.21 x (760-47) = 150mmHg
100
40
47
40
95
Types of Respiratory Failure
Hypercapnic RF:
PaCO2 > the patients normal value (> 45mmHg in a healthy person)
Pump Failure
Types of Respiratory Failure
Hypoxemic RF:
PaO2 < 60 mmHg
Lung Failure
Classes of Respiratory Failure
Type 1 Hypoxemic:
Mechanism =?
Etiology =?
Clinical Setting =?
Shunt
Airspace Flooding
Water, Blood or Pus filling the alveoli
Classes of Respiratory Failure
Type 2 Ventilatory:
Mechanism =?
Etiology =?
Clinical Setting =?
Decreased Va
Increased Respiratory Load, Decreased ventilatory drive
CNS depression, Bronchospasm, Stiff respiratory system, respiratory muscle failure
Classes of Respiratory Failure
Type 3 Post-op:
Mechanism =?
Etiology =?
Clinical Setting =?
Atelectasis
Decreased FRC and increased closing volume
Abdominal surgery, poor inspiratory effort, obesity
Classes of Respiratory Failure
Type 4 Shock:
Mechanism =?
Etiology =?
Clinical Setting =?
Decreased CO
Decreased FRC and increased Closing Volume
Sepsis, MI, acute hemorrhage
Important Equations
VE =?
VT x RR
VE is min ventilation
VE = alveolar respiration + deadspace
VA + VD
PaCO2 =?
K x VCO2/VA
PaCO2 ~ ?
VCO2/ (1 - VD/VT) x VE
Causes of Hypercapnic Respiratory Failure
CNS
Drugs
Disease of the medulla
Idiopathic (Odine’s curse)
Hypothyroidism
Central Sleep Apnea
Metabolic Alkalosis
Causes of Hypercapnic Respiratory Failure
Chest Bellows
ALS
Polio
Cord Injury
GBS
MG
Eaton Lambert myasthenic syndrome
phrenic nerve paralysis
NM d/o
tense ascites
post-op states
porphyria
fish toxins
critical illness polyneuropathy
Myopathy
Chest wall abnormalities
Causes Of Hypercapnic Respiratory Failure
Airway Disorders
Acute Asthma
COPD
Acute Hypercapnic Respiratory Failure
A decrease in CNS drive leads to?
Decrease in RR and VT
Acute Hypercapnic Respiratory Failure
A decrease in RR and VT leads to?
Decrease in VE and VA
Acute Hypercapnic Respiratory Failure
A decrease in VE and VA leads to?
Rise in PaCO2
Decrease in pH
Decrease in PaO2 (normal or mildly increased A-a gradient)
Decrease in pH
delta pH =?
0.008 x delta PaCO2
Hypoventilation
Patm O2 =?
PAO2 =?
PACO2 =?
PAH2O =?
PvO2 =?
PaO2 =?
150mmHg
50
80
47
40
45
Acute Hypercapnic Respiratory Failure
Decreased muscle strength leads to?
Decrease in VT Increase in RR
Microatelectasis, surfactant inactivation
Acute Hypercapnic Respiratory Failure
Decrease in VT and Increase in RR leads to?
Decrease in VE and VA
Rise in PaCO2, Decrease in pH
Acute Hypercapnic Respiratory Failure
Microatelectasis, surfactant inactivation leads to?
Decreased compliance
Decreased PaO2 (Increased A-a gradient)