Acid Base - The kPa Rules

Traditionally rules of thumb regarding the changes in PaCO2 and Bicarbonate in acid base balance have utilized mmHg. Unfortunately, in large tracts of the world, particularly in Europe, blood gases are reported in the SI unit kPa. This tutorial is for those people. I cover various acid base abnormalities - pH vs PaCO2, acute and chronic respiratory acidosis, respiratory alkalosis, metabolic acidosis and alkalosis and go through the various acid base rules of thumb using kPa, with examples. I guarantee you'll learn something.
Rules:
Rule 1 H+ vs pH: a 1nmol/L increase in [H+} results in a 0.01 fall in pH
Rule 2 PaCO2 in Apnea: In apnea the PaCO2 rises by 1.5kPa in the first minute and by 0.5kPa per minute thereafter (this reduces progressively over time to 0.2-3kPa)
Rule 3 PaCO2 vs pH: For every 1kPa increase in the PaCO2 the pH falls by 0.06
Rule 4 PaCO2 vs HCO3 in Acute Respiratory Failure: For every 1kPa increase in the PaCO2, the HCO3 rises by 1mmol/L
Rule 5 PaCO2 vs HCO3 in Chronic Respiratory Failure: For every 1kPa increase in the PaCO2, the HCO3 rises by 3mmol/L and the Chloride falls by an equal value.
Rule 6 PaCO2 vs HCO3 in Acute Respiratory Alkalosis: For every 1kPa increase in the PaCO2, the HCO3 falls by 2mmol/L
Rule 7 PaCO2 versus Base Deficit in Acute Metabolic Acidosis: For every 1mmol/L increase in the Base Deficit (-BE e.g. from -1 to -2), the PaCO2 falls by 0.13kPa
e.g. if the BD is -10 the PaCO2 will fall by 1.3kPa from 5.3 to 4
Rule 8 PaCO2 vs HCO3 in Chronic Metabolic Alkalosis (in ICU): For every 1mmol/L increase in the Base Excess (or HCO3) the PaCO2 increase by 0.13kPa
e.g. if the BE is +10 then the PaCO2 will increase from 5.3 to 6.6
Description
01:15 Introduction
02:15 Overview of Acid Base
05: 09 Clinical Scenario - Apnea for 10 minutes
06:26 pH versus H+
08:22 PaCO2 rise in Apnea
09:40 PaCO2 versus pH
11:45 Clinical Scenario - Community Acquired Pneumonia & Hypercarbia
14:40 PaCO2 vs HCO3 in Acute Respiratory Acidosis
15:45 Clinical Scenario - Chronic Respiratory Failure - Labs
18:00 Chronic Respiratory Acidosis PaCO2 vs HCO3
19:25 Clinical Scenario - Hyperventilating Patient
20:15 Acute Respiratory Alkalosis - PaCO2 versus HCO3
21:15 Clincal Scenario - Acute Metabolic Acidosis
22:35 PaCO2 versus Base Deficit in Acute Metabolic Acidosis
25:20 Metabolic Alkalosis - Clinical Scenario - Patient in ICU (prolonged stay)
27:40 A Short Overview of Metabolic Alkalosis in the ICU
30:13 Review
26:40 PaCO2 vs HCO3 in Metabolic Alkalosis (Chronic in ICU)
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