Jessica

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You might say I'm biased, but don't we have the best field in medicine?

The core business of critical care is mechanical ventilation. This page gives you an overview of the various articles I've written on the subject. So consider this a work in progress. The end goal? This should become a basic to advanced course in mechanical ventilation. See the roadmap below for the plans I have. I'm making this public so you can hold me accountable when I've slacked off ;)

Basics of mechanical ventilation


During normal breathing, expiratory time is usually twice the inspiratory time. This means that the I:E ratio is 1:2, or 1/3rd to 2/3rd. If you try to find this setting on the ventilator during support ventilation, good luck with that. Someone has decided it's way more convenient to give this setting a different name during support ventilation… it's either the End Inspiratory Cycle (EIC) on Macquets or the Expiratory Trigger Sensitivity (ETS) on Hamiltons. Seriously, Hamilton… the name doensn't even make sense. Also, the setting is a bit counter intuitive, so allow me to explain it.

The EIC (or ETS)…


So we've talked about the importance of safe mechanical ventilation and one way of quantifying safe mechanical ventilation during pressure support. We've also discussed driving pressure as an important parameter during mechanical ventilation, as it is directly related to mortality. Now get this, it's possible to measure driving pressure during pressure support! Sure, there are some caveats and considerations, but why am I so excited about this?

During COVID-19 we've obviously had a tremendous influx of patients with ARDS. A lot of these patients require mechanical ventilation for weeks. In early ICU admission phases, these patients are usually ventilated with…


This article covers triggering, cycling and basic ventilator modes and settings.

Consider a patient's respiratory rate of, for instance, 20 breaths per minute. One breath consists of an inhalation and exhalation. The ratio of inspiration to expiration is typically 1:2. This means that for 20 breaths per minute (i.e. 60 seconds), one breath cycle takes 60/20 = 3 seconds. Of these 3 seconds 1 second is used for inspiration (inspiratory time), and 2 seconds is used for expiration. These settings are available on your ventilator; we'll get back to that in a minute.

Triggering and cycling


Our lungs have 23 generations of airway branches. Surface area increases as we travel deeper within the lung. The functional unit of the lungs are the alveoli, responsible for oxygenation and ventilation, which together have a surface area of around 70 m².

For healthy individuals, total lung capacity (TLC, after maximal inspiration) is 6–8 liters. Residual volume (RV, after maximal expiration) is 2–2.5L. The difference between the two is called the vital capacity (VC), 4–6L. Functional residual capacity (FRC, after normal expiration) is 3–4L, which decreases when lying down, during anesthesia, etc. In short, everything that causes atelectasis. Anatomical dead…


An important parameter to guide safe mechanical ventilation is driving pressure. In this article, we learn how to calculate driving pressure, its origin, and most importantly, how to use it in clinical practice.

Driving pressure (DP or ΔP) is calculated by taking the difference between the pressure at end inspiration (when flow is 0) and the pressure at end expiration (when flow is 0). This means that during volume controlled ventilation, driving pressure is the difference between plateau pressure (Pplat) and total PEEP. Measurement thus requires an inspiratory and expiratory hold.


Patient Self Inflicted Lung Injury (PSILI) is a relatively new concept within mechanical ventilation. It implies that a patient can cause harm to their own lungs, creating barotrauma due to excessive transpulmonary pressure as a result of increased patient respiratory effort.

In Pressure Support mechanical ventilation it's not always easy to identify patients at risk of PSILI. This page will attempt to show you how.

Intensivist Dr. Bertoni proposed a method to estimate respiratory effort: he proposed that by performing an expiratory hold and determining the nadir of the pressure curve, you could determine the force that the patient is…


Dyssynchronies between inspiratory attempts of the patient and the inspiration by the ventilator could cause ventilator-induced lung injury (VILI). It is therefore important to recognize these dyssynchronies and act accordingly. On this page, you’ll find a quick overview of common dyssynchronies and how to treat them.

Jessica

I'm an intensivist and clinical pharmacologist, spreading the love for and knowledge of acute and critical care medicine on YouTube https://crit-ic.com/

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