One of the quirks of the LOs, is that some of them seem to cover half a textbook’s worth of information and then others, like this one, are very specific. This LO is closely related to yesterday’s post.
I was looking for a picture of the respiratory system compliance like the ones in West’s Respiratory Physiology and I came across a fascinating article discussing how difficult it is to teach the mechanics of breathing by John West himself. It includes the diagram I was looking for (fig 7) and also a little appendix on the requisite physics – bonus! It also has a discussion about dynamic compression of the airways (one of my pet topics)
BT_PO 1.13 Describe the elastic properties of the chest wall and plot pressure-volume relationships of the lung, chest wall and the total respiratory system
At FRC, the forces promoting chest wall expansion and those promoting lung collapse are in equilibrium T/F
Chest wall compliance is calculated by measuring the difference between intrapleural and alveolar pressure under conditions of respiratory muscle relaxation T/F
At high lung volumes, the chest wall has a tendency to collapse inwards rather than spring outwards T/F
A normally compliant chest wall is important for respiratory function T/F
With a large pneumothorax, the lung collapses and the thoracic cage expandsT/F
Something to think about. In the context of this topic, why does a flail segment caused by multiple fractured ribs compromise ventilation (apart from the fact is it very painful!)?
Well wasn’t yesterday a lucky day – thanks to a total brain fade on my behalf, there were two posts on the one day! I hope that you enjoyed them both.
This one sort of follows on from my post from yesterday, at least staying in the realm of the respiratory system. I am taking the chest wall to include the intercostal muscles because allows a bit more scope for statements.
I think you should know the answer to all of these. Answers in West Respiratory Physiology (at least my VERY old copy circa 1995 – I can’t imagine this is the sort of information which changes on a yearly basis) and Nunn’s Applied Respiratory Physiology.
BT_PO 1.6 Discuss the structure of the chest wall and diaphragm and the implications for respiratory mechanics
In normal people, the thoracic cage is an elastic body T/F
At FRC the intrapleural pressure is negative partly because the chest wall wants to spring outwards T/F
At high lung volumes (>75% TLC), the tendency for the chest wall to spring outwards disappears T/F
During inspiration, the ribs move upwards and forwards due to the effect of the external intercostal muscles T/F
During quiet expiration, the internal intercostals contract to draw the ribs back to a resting position T/F
The diaphragm has the capacity for an excursion of up to 10cm during forced respiration T/F
Contraction of the diaphragm results in an increase in the vertical dimension of the chest cavity only T/F
I wonder if this is another LO which appears elsewhere under another name. I find it hard to believe it has not already been covered, although my quick search cannot find another post on this area.
Clearly quite important to know this area in detail! I have added a few extra statements for you to sink your teeth into, because there is so much to consider.
The answer to all of the statements below can be found in Nunn’s Applied Respiratory Physiology which has an excellent chapter on the respiratory effects of anaesthesia.
BT_GS 1.60 Describe the physiological effects of anaesthesia on the respiratory system
FRC reduces upon induction of anaesthesia T/F
The reduction in FRC with anaesthesia is greater if the patient is paralysed rather than unparalysed T/F
The ventilatory response to hypoxia is attenuated by 0.2 MAC of volatile anaesthetic T/F
The ventilatory response to hypoxia is maintained during a propofol based anaesthetic T/F
The ventilatory response to hypercarbia is attenuated at lower levels of volatile anaesthesia compared to the hypoxic response T/F
Lung compliance is increased during anaesthesia T/F
Both shunt and dead space increase in anaesthetised patients T/F
All potent volatile anaesthetics (so excluding N2O) are bronchodilators, resulting in lower airways resistance in anaesthetised compared with awake supine patients T/F (this one requires a little bit more thought – the first part of the statement is true. See if you can work the second part out from first principles before looking up the answer)
I think this is another LO where you what you learn should be directed towards how it affects function rather than just memorising in detail the intricacies of the receptor itself.
The top 4 statements are core. The last one is the most interesting (I’ll try to find a good concise article on it for those who are interested and will update the post when I have). You will find the answers to the rest in, you guessed it, Hemmings and Egan 2e. There is also a nice summary article in BJA Educationhere.