Monthly Archives: September 2023

Help- The Patient’s Airway Pressures are STILL HIGH!

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In the previous tutorial we looked at the problem of high airway pressures and addressed inspiratory airway resistance in two ways: peak to plateau pressure gradient and dynamic and static inspiratory resistance.

In this tutorial we will look at three more ways of assessing airflow resistance: the identification and measurement of Auto-PEEP, Flow-Volume Loops and capnography.

Subsequently I discuss high airway pressure due to low total respiratory system compliance. I explain that when “compliance” is low – this may be a problem with the lungs as well as the chest wall – including the abdomen. I finish with the introduction into this course of Abdominal Compartment Syndrome.

50 Tutorials Uploaded! Now – Help the Patient’s Airway Pressures Are High!

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The alarm goes off like an air raid siren – everybody starts to panic – somebody starts to do the saturation countdown. There is nothing quite as distressing for the anesthesiologist or intensivist than for the ventilator to pressure cycle and fail to deliver tidal volumes due to high airway pressure.

Generally high pressures are caused by one of three things – a problem with the equipment (kinked tubing, patient biting the tubing etc.), an airway resistance problem (e.g. bronchospasm) or a pulmonary compliance problem (e.g. consolidation or pulmonary edema) or a combination of these. The first thing that the clinician should do when there pressure alarm goes off – is to silence the alarm and increase the Pmax.

Then go looking for the problem: start at the mouth and work your way back to the machine. If you can’t find a fault, put the patient on a manual breathing circuit and commence ventilation. If the patient is easy to bag, there is a machine problem, if difficult – then there is a problem with pulmonary resistance or compliance. In this first tutorial I look at assessing airway resistance. I do this in two ways. First I discuss peak to plateau pressure gradients and then look at airway resistance: dynamic versus static and how to calculate it. I will finish the discussion in the next tutorial.

Volume Pressure Loops – they are on every ventilator and anesthetic machine – look at them

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This tutorial looks at the pressure waveform in patients undergoing anesthesia or mechanically ventilated in ICU. All modern ventilators will provide a pressure time waveform and display volume pressure (often called “pressure volume” loops).

This tutorial commences with a discussion about pressure-flow loops – to demonstrate the relationship between flow and airway pressure. I then discuss and describe normal airway pressure versus time waveforms.

Subsequently I explore normal and abnormal dynamic volume pressure loops. I briefly discuss static VP-curves and why they are important in ARDS. Finally I demonstrate how you can measure real plateau pressure and static compliance by pushing one button and performing an inspiratory hold.

@ccmtutorials http://www.ccmtutorials.org

Flow Volume Loops in Anesthesia and Critical Care

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There is a feature on the display of you ICU ventilator or anesthetic machine that you likely pay little attention to – the flow volume loop. Indeed, you may ignore the flow-time waveform also. This is a pity – and you are missing out on tons of information about your patient.

This tutorial commences with a description of the flow waveform (no previous knowledge required!) and the different waveforms that you are likely to encounter – sinusoidal, constant flow, decelerating flow and “shaved-off” decelerating flow (associated with pressure support).

I then show you a series of flow volume loops and – yes you can pause the video and see if you can figure out what is going on with the patients.

If you find this and my other videos useful – do me a favor and subscribe: subscriber only content coming soon.

 @ccmtutorials  http://www.ccmtutorials.org