Assessing Ventilation (Carbon Dioxide)

This tutorial looks at the assessment of PaCO2 on the blood gas and how it interfaces with the pH and the Bicarbonate (HCO3-). The control of PaCO2 is a major physiological mechanism for maintaining homeostasis. CO2 production by the body must be balanced by CO2 elimination. PaCO2 rises when there is hypoventilation, this results in a fall in pH and an rise in HCO3 and this is called "Acute Respiratory Acidosis." If the patient hyperventilates, the PaCO2 and the HCO3 fall and the pH rises: this is "Acute Respiratory Alkalosis." When there is chronic CO2 retention, the body adapts by wasting Chloride in the urine, the pH normalizes and the HCO3 rises substantially.
Any patient who is intubated, or who has a laryngeal mask in situ, must undergo end tidal (end of exhalation) CO2 monitoring. The capnography waveform is worth evaluating, particularly if airway obstruction or increased resistance is suspected.
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Description
00.00 Introduction and Review
01:17 The Importance of CO2 and Ventilation
04:27 Hypercarbia and Why it Occurs
05:41 Failure to Generate Adequate Minute Ventilation
07:50 Carbon Dioxide Metabolism
09:03 Carbon Dioxide Content of Blood
09:56 Capnometry
10:25 Blood Gas PCO2
11:10 The Rule of 40
12:11 Acute Respiratory Acidosis
13:23 Acute Respiratory Alkalosis
14:39 Chronic Respiratory Acidosis
16:08 PaCO2 Targets
17:38 PaCO2 and Minute Ventilation
18:30 Acute Metabolic Acidosis
19:00 Hypercarbia and the Non Ventilated Patient
20:10 Hypercarbia and the Ventilated Patient
21:00 Capnometry and Capnography
25:02 Review and Preview