Invitees:
Andrew Marchant Ian Green Cato Christian Spook Steven Dain Katarina Lindve Farzaneh Ashrafi
Apologies:
Patrick McCormick Monica Harry
Present:
Anesthesia Clinical Reference Group
Time: Tuesday, April 8, 2025 15:30 - 17:30 Oslo / 13:30 - 15:30 UTC / 14:30 - 16:30 UK / 9:30 - 11:30 ET
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| Item | Description | Owner | Notes |
|---|---|---|---|
| 1 | Introductions and Apologies | ||
| 2 | Matters arising from the previous meeting notes | ||
| 3 | SNOMED Update | SNOMED is widely adopted across Sweden, and thanks were expressed for Sweden's hospitality during the Business Meeting. Ian will be working on a part-time basis. A new manager has been appointed to support the needs of the rest of Europe. Forthcoming Expo and Business Meetings were discussed. | |
| 4 | Ventilation new concept requests | General approach noted: Discussion was held around proposed terms for modes of ventilation. The results were returned to the content management team. Several terms were not felt to usefully extend the existing classification, one appeared to describe a concept which SNOMED should reflect, and some were reserved for further discussion. Ventilator classification will have to reflect increasingly sophisticated control systems, which will often be computerised and have AI features. Additionally it was noted that some proposed systems made use of multiple inputs (perhaps including lab or physiological data) and some operated over a longer timescale than has hitherto been part of the control systems of ventilators (with blurring into the realms of clinical decision-making). These latter were reserved for future discussion. | |
| 5 | Items for future discussion | All | |
| 6 | Dates of next meeting | Next meeting Tuesday May 27, 2025 |
2 Comments
Monica Harry
Please accept my apologies, I will not be able to attend this call today as I have to facilitate another meeting. Farzaneh Ashrafi will attend in my place. Farzaneh Ashrafi Ian Green
Steven Dain
Monica Harry Andrew Marchant Ian Green Cato Christian Spook I looked at Monica's spreadsheet and added to it after the meeting. Feel free to comment on the changes.
After the SNOMED meeting today, for fun I had a chat with Chatgpt. I don't agree with everything it says, but it was entertaining and illustrates the confusion in ventilation terms.
The transcript is below. I started by asking:
what is assisted breathing?
ChatGPT said:
Assisted breathing refers to any method where a person receives help to breathe, either partially or fully, because they are unable to do it effectively on their own. This support can be provided by machines, devices, or manual techniques. It’s commonly used in medical settings for people with respiratory issues or during surgery.
Types of Assisted Breathing:
Mechanical Ventilation – A machine (ventilator) pushes air into the lungs through a tube in the mouth (intubation) or a tracheostomy.
CPAP/BiPAP – Machines that deliver pressurized air through a mask to keep airways open, often used for sleep apnea or milder breathing problems.
Bag-Valve-Mask (BVM) – A manual method where a caregiver squeezes a bag to push air into the lungs, usually in emergency situations.
Negative Pressure Ventilators – Like the old "iron lung," these draw air into the lungs by creating a vacuum around the body.
Why It's Used:
Respiratory failure
During anesthesia in surgery
Severe asthma or COPD
Overdose or trauma
Neuromuscular disorders (e.g., ALS)
Let me know if you want a deeper explanation of any specific type or situation!
4o
You said:
how does artificial ventilation differ?
ChatGPT said:
Great question! Artificial ventilation and assisted breathing are closely related, but they’re not exactly the same. Here's how they differ:
Assisted Breathing
Definition: The patient is still initiating breaths on their own, but they get help (assistance) to make those breaths more effective.
Key Point: The patient participates in breathing.
Examples:
BiPAP/CPAP machines
Some modes on a ventilator (like pressure support)
Manual bagging where the patient is still breathing some on their own
Artificial Ventilation
Definition: Breathing is completely taken over by a machine or device because the patient can’t breathe on their own at all.
Key Point: The machine does all the work of breathing.
Examples:
Full mechanical ventilation in a coma or under anesthesia
Ventilation during CPR
Use of a ventilator when a person is paralyzed or deeply sedated
(Note that I don't agree with this definition, ISO TC 121 definition is artificial ventilation --intermittent elevation of the pressure in the patient's airway (3.8.1.1) relative to that in the lungs by external means with the intention of augmenting or totally controlling the ventilation of a patient)
In Short:
Assisted breathing = help with natural effort.
Artificial ventilation = machine breathes for the person.
Let me know if you want to get into the different ventilator settings or how the body reacts to each!
4o
You said:
Hmm what is supported ventilation?
ChatGPT said:
Nice follow-up! Supported ventilation is kind of a middle ground between assisted and artificial ventilation. It's a term often used in ventilator settings to describe when the machine helps the patient only when they initiate a breath—but doesn't force them to breathe if they don’t try.
Supported Ventilation: Key Points
The patient starts the breath, and the ventilator supports it.
It’s used when someone can breathe somewhat on their own but not strongly or consistently.
Common in recovery phases or in conditions like COPD or during weaning off a ventilator.
Common Modes of Supported Ventilation:
Pressure Support Ventilation (PSV):
The patient breathes spontaneously.
The ventilator adds a set amount of pressure to assist each breath.
CPAP with pressure support:
Continuous pressure keeps airways open, and extra support is added when the patient inhales.
BiPAP (in non-invasive settings):
Delivers higher pressure when inhaling (IPAP) and lower when exhaling (EPAP).
So, compared to the others:
(These are the terms from ISO 19223)
Supported ventilation is like having a spotter at the gym: you're lifting the weight yourself, but there's help right there if you need it.
Want to dive into any of those ventilator modes in more detail?
4o
You said:
What is the difference between pressure support ventilation and CPAP with pressure support?
ChatGPT said:
Great question—this one trips up even some clinicians in training! Let's break it down clearly:
Pressure Support Ventilation (PSV)
What it is: A mode of invasive ventilation (via an endotracheal tube or tracheostomy).
How it works: The patient initiates every breath, and the ventilator provides a set amount of pressure to help them inhale.
Baseline pressure (PEEP): Often added, but optional.
Use case: Commonly used during weaning from the ventilator.
Key point: There is no mandatory breath delivery—if the patient doesn't breathe, nothing happens (unless backup is set).
CPAP with Pressure Support
What it is: A non-invasive form of ventilation (via a mask).
CPAP: Provides continuous pressure during the entire breathing cycle to keep airways open.
Pressure Support: Adds an extra boost during inhalation only, on top of the baseline CPAP.
Use case: Often used in sleep apnea, COPD, or early respiratory distress.
Key point: CPAP + PS mimics PSV, but through a mask rather than a tube.
Side-by-Side Summary
Bottom Line:
PSV = invasive support mode on a ventilator.
CPAP with PS = non-invasive version, often used outside the ICU.
Let me know if you want to go over IPAP/EPAP numbers or how these modes look in real-life patient scenarios!
4o
You said:
This is just semantics. Are they not both the same thing except one is invasive and one non-invasive. Isn't it confusing to have 2 different names for the same thing ontologically?
ChatGPT said:
YES. You’re absolutely on point—and you’ve hit on a really important nuance in medicine: sometimes, different names are used for what are functionally the same physiological concepts, just because they occur in different contexts (like invasive vs. non-invasive settings).
You're Totally Right:
At their core:
PSV (invasive) and
CPAP with pressure support (non-invasive)
...are essentially the same mode of ventilation, just delivered differently.
Both:
Rely on the patient to trigger the breath.
Provide pressure during inspiration to assist the breath.
May or may not have a baseline pressure during exhalation (PEEP or CPAP/EPAP).
So yes—ontologically, they are the same species of support. The only real distinction is interface (tube vs mask), and that’s a pragmatic difference, not a fundamental one.
Why the Confusing Names Then?
Medicine loves tradition and compartmentalization (), so we end up with:
Different names based on the ventilator's mode labels (which differ between invasive and non-invasive devices).
Different clinical workflows (ICU vs sleep lab vs emergency room).
Different teams using them—respiratory therapists, intensivists, pulmonologists—each with their own language.
So the names serve as shorthand to indicate not just the physiology, but also the context, setting, and equipment involved.
So in summary:
You're right to feel it’s semantic. It’s the same mechanism, just packaged differently depending on the setting. And yes, the naming can be unnecessarily confusing.
If medicine were starting from scratch, we’d probably just have:
"Pressure support ventilation (non-invasive)"
"Pressure support ventilation (invasive)"
But alas... tradition.
Want to go deeper into how ventilators label these modes or how different brands confuse it even more?
4o
You said:
So then, what is hybrid ventilation? How does that differ?
ChatGPT said:
Yesss now we’re really diving in
Hybrid ventilation is a broader, newer concept—and you’re gonna love this because it ties everything together.
What is Hybrid Ventilation?
Hybrid ventilation refers to any ventilation strategy or mode that blends features of both assisted and controlled ventilation, or spontaneous and mandatory breaths, within the same mode.
Basically, it's a system that:
Gives the patient some room to breathe on their own, but...
Steps in to give full support if needed.
Think of it like adaptive cruise control in a car: you’re in control until you’re not—then it takes over to keep you safe.
Examples of Hybrid Modes:
SIMV (Synchronized Intermittent Mandatory Ventilation)
Delivers mandatory breaths at a set rate.
Allows the patient to breathe spontaneously in between, with or without pressure support.
APRV (Airway Pressure Release Ventilation)
Keeps lungs open at a high pressure (like CPAP), but intermittently drops to a lower pressure to allow passive exhalation.
Patient can breathe spontaneously throughout.
NAVA (Neurally Adjusted Ventilatory Assist)
Uses signals from the diaphragm to tailor support to each breath.
Fully hybrid because the machine matches the patient's natural effort, second by second.
Adaptive Support Ventilation (ASV)
Automatically adjusts the level of support based on the patient’s lung mechanics and effort.
Patient can go from fully passive to mostly independent, and the machine adapts.
So How’s It Different from PSV or CPAP+PS?
Bottom Line:
Hybrid ventilation is not just about pressure delivery, it's about how flexible the mode is in responding to the patient. It’s patient-tailored, blending:
Support when they need it
Autonomy when they don’t
Safety net all the time
So it’s not just a mode—it’s a strategy. A more dynamic, responsive way of ventilating someone.
Want to look at a real-life scenario comparing these modes in an ICU setting?
4o
You said:
Isn't a ventilation "strategy" the same as a "ventilation mode"? Who are you trying to kid here?
ChatGPT said:
Okay, okay—fair play! That’s a very fair challenge.
Let’s unpack that, because you're absolutely right to question the language here. The terms ventilation strategy and ventilation mode often get used interchangeably, but they’re not exactly the same—and the distinction actually does matter once you zoom out a bit.
Ventilation Mode = How the machine delivers breaths
It’s the technical setting on the ventilator.
Tells the machine:
How to deliver breaths (volume vs pressure)
When to deliver them (timed vs patient-triggered)
How much to support (full vs partial)
Examples:
Volume Control (VC)
Pressure Control (PC)
Pressure Support (PS)
SIMV
CPAP
BiPAP
NAVA
ASV
It’s like choosing the gear in a car.
Ventilation Strategy = The clinical approach/plan behind the settings
It’s the why and when we choose certain modes and settings.
Based on:
Patient’s condition (ARDS? COPD? Neuro issue?)
Goals (oxygenation, CO₂ clearance, lung protection, weaning?)
Tolerance of the mode
Risk of lung injury, barotrauma, etc.
Examples:
Lung-protective strategy (low tidal volumes)
Permissive hypercapnia
Weaning strategy using pressure support
Hybrid strategy using SIMV + PS
Non-invasive support as first-line therapy
It’s like choosing how you want to drive: aggressively, conservatively, off-road, highway cruise, etc.
So...
TL;DR:
You're right—in casual conversation, people throw these terms around like they're the same.
But technically:
Mode = what the vent does.
Strategy = why and how we use it in context.
No kiddding—just trying to make sense of the jargon jungle with you. Want to roast ventilator settings next? Or look at how modes map to different clinical goals?
I ran out of quarters to put into the machine....
Steven