Category Archives: Respiratory Failure

Everything You Need to Know About End Tidal CO2

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I decided to do a tutorial on end tidal CO2 as there has been a lot of discussion about it’s merits and limitations in our practice. It is fairly long and can be broken into sections at 20 minutes and 37 minutes if you have a short attention span (I will split it up into smaller segments at some stage in the future).

The content is absolutely essential for doctors and nurses working in anesthesiology and intensive care. In my opinion measuring expiratory CO2 from the ventilator circuit is the most useful clinical measurement tool that we have. It gives us information about cellular metabolic activity, blood flow, venous return, lung unit perfusion, gas exchange and alveolar ventilation. The tutorial commences with a discussion of CO2 as a gas and discusses Henry’s and Daltons’ laws. I then discuss the various different CO2 moieties, particularly bicarbonate. Subsequently I go on to discuss the impact of alveolar ventilation on PaCO2. After 20 minutes I move on to discuss capnometry – the measurement of the presence and quantity of CO2 emerging from the lung at end expiration. I discuss why the etCO2 may rise of fall. I then look at a specific clinical scenario where the etCO2 falls precipitously. After 37 minutes I discuss capnography – initially the normal capnograph and then a series of different capnography traces that you should be able to recognize. As a final thought I mention that CO2 is not the only waste produce or metabolic intermediary that we measure, routinely, in clinical practice.

Tutorial 6: Synchronized Intermittent Mandatory Ventilation

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This is the second tutorial on Volume Controlled Ventilation. I discuss the evolution of ventilators from pure controlled mechanical ventilation, to intermittent mandatory ventilation – with spontaneous breathing to synchronized IMV with Pressure Support. This mode remains robustly popular around the world and critical care practitioners and anesthesiologists should be familiar with the mode, along with its advantages and disadvantages. I guarantee you will learn something. @ccmtutorials

Tutorial 4 – Cycling The Mechanical Ventilator

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This is the last tutorial in the introductory module – “setting up a mechanical ventilator.” In this tutorial I will discuss how the ventilator cycles from inspiration to expiration. In controlled modes this is usually time cycling. However, traditionally volume cycling of volume control was used. On occasion the ventilator pressure cycles – and you must be aware of this as it may cause problems. Finally I will introduce the concept of flow cycling: it is imperative that you understand this process if you use pressure support ventilation. I guarantee you will learn something in this tutorial.

Next week we will be moving on to Volume Controlled Ventilation – specifically Volume Assist Control.

Announcing Mechanical Ventilation Course

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I have received quite a lot of feedback over the years regarding the original ccmtutorials website and what is apparent to me is that the Mechanical Ventilation Tutorials were unfailingly popular.
Fortunately I have delivered quite a few Mechanical Ventilation lectures and tutorials over the past few years. I have redone, reworked and rethought all of this material through and now I am announcing a new version of the Mechanical Ventilation Tutorials for the 2020s. The tutorials will start to stream this week.

The first part of the course is titled: “Setting Up A Mechanical Ventilator” and this contains four tutorials.
1. Ventilator Control: Volume Control and Pressure Control
2. Flow Patterns
3. Triggering
4. Cycling
Please follow these tutorials sequentially – you might think you know a lot about mechanical ventilation; you do not.
Here is the intro spiel to the first module of the course:
If you have ever sat into an unfamiliar car – a rental car or a new car for example – you need to take some time to figure out the controls. How does it start ? Manual or Automatic? Left or right sided drive? Where is the hand break – lever or button? The lights? The wipers? The de-mister? The radio? How you connect your phone etc. Before you ever put a patient onto a ventilator you need to understand how the machine works and how to set it up. This tutorial will look at the basics of setting up a ventilator – and this is essential material. Do not skip onto the next tutorial until you have learned this material.

(note I haven’t forgotten the fluid course – Hyponatremia and Hypernatremia to feature soon).

Pat Neligan Jan 2023