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Respiratory Failure Ch. 2
Terms in this set (41)
failure of the lungs to provide adequate oxygenation or ventilation for the blood/tissues
types of respiratory failure
-acute hypercapnic respiratory failure
-acute hypoxemic respiratory failure/ventilatory
PaO2 <60mmHg at FiO2 >.5
PaCO2 >45 mmHg
Etiology of Oxygenation failure
-decrease O2 in the blood
-can lead to hypoxia
-inadequate tissue oxygenation
When hypoxemia is present how can oxygenation be preserved?
by increasing CO but in patients that already have decreased cardiac function, CO may not be able to be increased enough to make up for the hypoxemia
What happens if hypoxia occurs at the heart's tissues?
this problem can cause arrhythmias & poor contractility
The most common cause of hypoxemia?
V/Q mismatch, where you have poor ventilation but are perfusion (low V/Q) or you have an area of adequate ventilation but poor perfusion (high V/Q)
adequate ventilation but poor perfusion
ex: pulmonary embolism
poor ventilation but adequate perfusion
ex: COPD emphysema, asthma, & pneumonia
Another cause of hypoxemia?
shunting (movement of blood from right to left side of the heart w/out coming into contact w/ ventilated alveoli for gas exchange)
anatomic shunt causes?
physiologic shunt causes?
unventilated alveoli (low V/Q) & would see refractory hypoxemia
examples of hypoxemia caused by inadequate PIO2
-equipment failure: breathing 100% helium w/out mixed in O2
increased PACO2 & decreased PAO2
Etiology of Ventilatory failure
-depression of respiratory centers
-spinal cord abnormalities
-thoracic cage abnormalities
-upper & lower airway obstruction
-malnutrition & electrolyte disturbance
Depression of respiratory centers in the brain
-depression of ventilation w/ increased O2
-guillian barre syndrome
a neuromuscular disease like spinal cord abnormalities where the brain can not transmit signals to the lungs
can weaken ventilatory muscles making them less efficent
PaO2 60-80 mmHg
PaO2 40-60 mmHg
PaO2 <40 mmHg
Patients response to hypoxemia depends on?
-pre existing conditions & severity of hypoxemia & length of time
-tachypnea & tachycardia are the most common responses
will normal healthy people be affected by mild hypoxemia?
what type of patients would be affected by mild hypoxemia?
patients w/ underlying cardiopulmonary disease w/ low reserve will be gravely affected.
Why does your body respond to hypoxemia w/ increased RR & HR?
bodys natural compensatory response to increase VE, decreasing PACO2 & hopefully increasing PaO2.
tachypnea can increase?
work of breathing & can be bad for patients w/ an underlying disease
increase HR increases?
CO which will increase cardiac work & can lead to ischemia & even infarction
bodys response to oxygenation failure in order
1. increased pulmonary vascular resistance
2. increased right ventricular workload
3. ventricular failure
4. Cor pulmonale
what does hypoxemia stimulate?
pulmonary capillaries to constrict which will increase pulmonary vascular resistance, which increases work on right heart & after a period of time results in Cor pulmonale
drug overdose w/ ventilatory failure
-decreases drive to breath, increases PaCO2, decreases pH & causes acidosis.
-combination of high PaCO2 & low pH causes the brain function to slow like an anesthetic & results in coma
Oxygenation failure physical examination
-tachycardia, tachypnea, hypertension
-altered mental status
-Cor pulmonale: hepatomegaly, JVD, pedal edema
Oxygenation failure lab abnormalities
-Polycythemia if chronic
-chest radiograph often normal if extra pulmonary cause
Ventilatory failure clinical findings
-headache -diminished alertness
-warm& flushed skin -bounding peripheral pulses
-hypothermia & altered mental status= drug OD
-tachycardia& hypertension= tricyclics
-respiratory alternans or abdominal paradox= diaphragmatic fatigue
Ventilatory failure lab abnormalities
-elevated total CO2 on electrolyte panel
Treatment of Oxygenation failure
-supplemental oxygen (V/Q mismatch)
-Positive Pressure ventilation-CPAP (shunt) if PaO2 <60 mmHg at FiO2 >.50
-mechanical ventilation if CPAP is unsuccessful
continuous positive airway pressure
-holds a pressure in the alveoli above atmospheric.
Treatment for ventilatory failure
-VT 5-10 ml/kg IBW
-Keep Plateau < 35 cmH2O
-RR according to age & metabolic rate
-FiO2 adjusted w/ pulse oximetry
Weaning criteria from mechanical ventilation associated w/ respiratory failure
-Etiology/ventilatory failure resolved
-patients condition stable & improving
-vital capacity > 10-15 mL/kg
-resting minute volume < 10 L/min
-MIP > -20cmH2O
-adequate oxygenation on FiO2 <.50
-spontaneous RR < 35 breaths/min
-spontaneous tidal volume >325 mL
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