What is respiratory failure?
- Occurs when here is inadequate oxygen delivery to the cells. This can occur with hypotension. It is also described as failure of the cell’s ability to USE oxygen as seen in cyanide poisoning and carbon dioxide poisoning
- If respiratory failure is generalized throughout the body with extensive cellular deprivation, the term shock applies
What is Mixed venous oxygen saturation and what is it used for?
- It is best defined as the percentage of oxygen bound to hemoglobin in blood returning to the right side of the heart (SVO2)
This reflects the amount of oxygen "left over" after the tissues remove what they need. It is used to help us to recognize when a patient's body is extracting more oxygen than normal
- It is used to help assess tissue oxygen delivery in unstable patients
Why would there be a decrease is SVO2?
- An increase in extraction is the body’s way to meet tissue oxygen needs when the amount of oxygen reaching the tissues is less than needed.
- SVO2 varies directly with SaO2 and cardiac output.
The normal SvO2 is 65-75%, which denotes adequate tissue oxygenation.
What is Hypercapnic Respiratory Failure?
Occurs with an acute elevation of carbon dioxide > 45 mmHg producing a respiratory acidosis. This condition primarily occurs due to ventilatory failure.
What is hypoxemic respiratory failure?
Hypoxemic Respiratory Failure occurs when normal gas exchange is seriously impaired causing a PaO2 < 60 mmHg. There is usually associated tachypnea and hypocapnia but can progress to hypercapnia. It is usually the result of the lung’s ability to deliver oxygen across the alveolocapillary membrane.