Respiratory Failure Flashcards
What is respiratory failure?
A potentially life-threatening deterioration in the gas exchange function of the respiratory system:
- Impairment of oxygenation
- Inadequacy of CO2 excretion
- A mixture of both
What is the precise site of O2 and CO2 exchange ?
the respiratory unit (respiratory bronchioles + alveoli)
What can confirm respiratory failure from history and physical exam?
Arterial Blood Gases (ABG’s) are required to confirm the diagnosis
What are some symptoms of resp failure?
Dyspnea Fatigue Headache Anxiety Confusion
What are signs of resp failure?
Tachypnea Bradypnea Altered mental status Cyanosis Accessory Muscle Use Indrawing Paradoxical abdominal breathing
What are normal ABG values?
PaO2 > 60 mm Hg
PaCO2 = 40 mm Hg
[H+] = 40 nM/l (pH = 7.40)
[HCO3-] = 24 mmol/l
What are the type of respiratory failure?
Impaired Oxygenation (Type I)
Hypoventilation (Type II)
Mixed (Type III)
What can be indicated by an abnormal Abnormal A-aDO2, in the presence of high PAO2, low PaO2 and low PaCO2?
Oxygen impairment (due to diffusion limitation)
What is hypoxemia?
PaO2 < 60 mm Hg and/or SaO2 < 90%
What causes hypoxemia in normal lungs?
↓ FiO2
↓ barometric pressure
Hypoventilation
What causes hypoxemia in abnormal lungs?
Shunt
VQ mismatch
Diffusion impairment
Impaired cardiopulmonary function
What is hypercapnia?
PaCO2 > 40 mm Hg +/- acidosis
What causes hypercapnia?
↑ CO2 production
↑ Deadspace ventilation
↓ Minute ventilation
What causes increased CO2 production?
Fever, sepsis, seizures, exercise, excessive carbohydrate loads in diet
T or F: ↑ CO2 production leads to hypercapnia only when there is co-existing cardiopulmonary dysfunction
T
What conditions would increase dead space ventilation?
COPD, asthma, cystic fibrosis, pulmonary fibrosis, thoracic cage abnormalities,
What is minute ventilation?
Minute ventilation refers the to volume of air entering and leaving the lungs per unit time (liters/minute)
What causes a decrease in minute ventilation?
CNS/respiratory center depression Spinal cord lesions Peripheral nerve dysfunction Disorders of the neuromuscular junction Respiratory muscle weakness Structural abnormalities of the chest/thoracic spine (scoliosis) Upper airway, lung or pleural disease
What are causes of ventilation failure?
Drug-induced CNS depression (resp center)
Metabolic alkalosis
Traumatic quadriplegia (peripheral nerve)
Guillain-Barré Syndrome (peripheral nerve/muscle weakness)
Myasthenia gravis (neuromuscular junction)
Phrenic nerve paralysis
Hereditary myopathy (DMD)
T or F: Immediate management of resp failure is not required
F: required
How to manage respiratory failure?
Rapid evaluation
ABC’s/resuscitation
Support: oxygen, ventilatory support
Specific treatment for the underlying cause
What does ABCs involve?
A - Airway
Assess if patient able to speak (good if can), look for edema, blood, vomitus, foreign body
B - Breathing --> abnormal then CPR Look for work of breathing, respiratory rate Listen to breath sounds Feel the air at mouse and nose Check for pulse oximetry (O2 Sat)
C - Circulation
Assess mental status, color
Feel peripheral pulses
Check HR, rhythm, BP
What are the two types of supportive therapy for resp failure?
Oxygen &
Ventilation
What are ways to give O2 (21%)?
Nasal prongs/cannulae
Venturi mask
CPAP
Simple or reservoir mask
Same as ventilation and O2:
Bag + mask devices
BiPAP
Endotracheal tube/tracheostomy + positive pressure mechanical ventilation
How to give ventilation?
Mouth-to-mouth or mouth-to-mask rescue breathing
Negative pressure ventilation (“iron lung”)
Bag and mask devices
BiPAP
Endotracheal tube/tracheostomy + positive pressure mechanical ventilation
HOw much O2 to give?
Give enough O2 to keep SpO2 at least 90% (PaO2 55 mm Hg)
Treat hypercapnia/hypoventilation if/when develops
