Thursday, August 15, 2013

Three things I learned: respiratory pathophysiology

dogs study with Anne
Online learning: dogs LOVE it!
Unless you are an ubernerd (more power to you) the word pathophysiology probably makes you want to run away...which is precisely why you should pay attention to any course with the word in its name (or even the word physiology!). I don't know about you but this stuff is challenging to teach and challenging to learn, so a review on the subject is always welcome and I always pick up something new (or learn about something old in a new way).

This month I'm enrolled in the Centre for Veterinary Education's TimeOnline on Respiratory physiology, monitoring and basic support.

Don't get me wrong...I am very much a fan of attending courses. But its nice to be able to take one at one's own pace. This course is great - you can take it as light or deep as you want. You can just read the notes and coast through, or you can read the supplementary materials and watch the videos and pick up a lot more.

So what did I learn or remember this week?

  1. There are type I and type II alveolar cells (aka pneumocytes). Type I are very thin and enable gas diffusion. Type II are fatter, and produce surfactant which is essential for alveolar stability. But Type IIs are capable of cell replication and can turn into type I's.
  2. Oxygen toxicity leads to damage and loss of Type I's (thin walls make them more fragile). Where there is inflammation and destruction, type II's proliferate, but they are thicker so there is a diffusion impairment of oxygen into the blood. As part of alveolar repair they will eventually turn into type I's but you want that process to happen rapidly.
  3. In acute respiratory distress syndrome, type II's have reduced capacity to produce surfactant - leading to increased alveolar instability and collapse.
Surfactant therapy during these episodes sounds like a sensible idea but apparently, despite improving oxygenation which makes sense, it doesn't decrease mortality.

We covered lots more this week including anatomy, the principles of ventilation, regulation of respiration, oxygenand gas transport across alveoli, ventilation/perfusion ratios, water balance in the lung, oxygen transport from lung into tissues, CO2 transport from tissues to lungs and other functions of the lungs (such as filtering), but I'm restricting myself to three things.