Respiratory Failure Flashcards
What is respiratory failure defined as?
PaO2 less than 60 or PaCO2 more than 55
What is Type I (acute hypoxemic) RF?
when PaO2 is low and PaCO2 is normal
What is Type II RF?
When PacO2 is high and PaO2 is low
When does Type I RF occur?
occurs with diseases that damage lung tissue. Common causes include cardiogenic pulmonary edema, pneumonia, acute lung injury and lung fibrosis.
When does Type II RF occur?
occurs when alveolar ventilation is insufficient to excrete the volume of carbon dioxide being produced by tissue metabolism
Most common causes of Type II RF?
Chronic obstructive pulmonary disease (COPD).
Other causes include chest-wall deformities, respiratory muscle weakness (e.g. Guillain–Barré syndrome) and depression of the respiratory center (e.g. overdose).
What should be done if RF is suspected?
blood gas analysis
The most sensitive clinical indicator of increasing respiratory difficulty is____
rising respiratory rate. Measurement of tidal volume is a less sensitive indicator.
_____ is often a better guide to deterioration and is particularly useful in patients with respiratory inadequacy that is due to neuromuscular problems such as the Guillain–Barré syndrome or myasthenia gravis, in which the vital capacity decreases as weakness increases.
Vital capacity
How can RF be monitored?
- pulse oximetry
- BGA
How does pulse oximetry work?
Lightweight oximeters can be applied to an ear lobe or finger. They measure the changing amount of light transmitted through the pulsating arterial blood and provide a continuous, non-invasive assessment of arterial oxygen saturation (SpO2).
These devices are reliable, easy to use and do not require calibration, although remember that pulse oximetry is not a sensitive guide to changes in oxygenation.
An S p O 2 within normal limits in a patient receiving supplemental oxygen does not exclude the possibility of hypoventilation with carbon dioxide retention. Readings are occasionally inaccurate in those with poor peripheral perfusion.
Rules to BGA:
▪ The sample should be analysed immediately. Alternatively, the syringe should be immersed in iced water (the end having first been sealed with a cap) to prevent the continuing metabolism of white cells causing a reduction in P O 2 and a rise in P CO 2 .
▪ Air almost inevitably enters the sample. The gas tensions within these air bubbles will equilibrate with those in the blood, thereby lowering the P CO 2 and usually raising the P O 2 of the sample. However, provided the bubbles are ejected immediately by inverting the syringe and expelling the air that rises to the top of the sample, their effect is insignificant
What is the difference between respiratory and ventilatory failure?
Respiratory failure is when regardless of how well you are breathing, oxygen is not diffusing well into blood. Ventilatory failure is usually characterize by hypercapnia
Which cause of hypoxemia have a normal A-a gradient?
hypoventilation and decreased PiO2
Normal A-a gradient= no lung disease
