Deresuscitation has become more and more ubiquitous within ICU practice. But what tools can we use to do it? Over the next 2 Tweetorials, i’ll explain some pharmacological methods. Focussing on the JICS mix!
The brilliant paper in question is well worth a good read through. For both its novel description of combination diuretic therapy, and its golden descriptions of simple and complex fluid/renal physiology.
We know, universally, oedema on the ICU is contentious. Early goal directed therapy trials after Shoemaker, all demonstrated worse outcomes. Why?🤔
There were signals towards positive fluid balance and probably states of venous congestion in the treatment arms.
The FACCT trial signalled better outcomes amongst ALI/ARDS patients kept on the ‘dry side’. Fewer ventilator days, better lung function and reduced ITU stay.
Note - there was a 12h delay until after shock resolution, before diuresis took place🤷♂️🤔
IV fluids are sadly an obsession and have become a reflexive prescription. Although almost any crystalloid is safe early in resuscitation, the amplification effect of over-prescription can be very harmful to patients.
Moreover - many contain supra-physiological amounts of Na+!
We’ve evolved to hold onto sodium. Probably to help maintain intravascular volume and body electrolyte composition during times of extreme stress.
This doesn’t help when critically Ill / stressed or worse, when we’ve been overloaded with too much sodium containing fluid!🙈
It gets even worse in hospital, when we have surgery or are critically Ill!
We release too much ADH (that Neanderthal protective mechanism), and hold onto water = oedema ultimately!
Even worse I’m afraid🙈
The kidneys also hold onto more sodium - and we pee out potassium. We are now ill, boggy, hypernatraemic and hypokalaemic🤯🙄
What we often end up doing, is becoming a little too obsessed with diuresis. We overdo it, creating problems we then end up chasing with more fluid …and it’s Groundhog Day!
What we should perhaps be considering is NATRIURESIS😉🤷♂️ Get rid of that cation that’s glued in!
It’s a very fine balance though. We don’t want electrolyte issues, nor do we want to cripple the vital intravascular volume supplying suffering vital organs during panendothelial dysfunction states, by dehydrating patients!
We discuss R.O.S.E and the 4 phases of fluid therapy.
Resus
Organ support
Stabilisation
Evacuation
We should really only have one phase - resuscitation and then standard maintenance. Period🤷♂️ why go too far and have to remove it..ideal world, I know!
Take a look at this aide-mémoire graphic of the important parts of the nephron….
Remind yourselves of the different sections, as it’s all going to be very relevant to helping the patient later on.
Solute passes through the nephron, first into the Proximal Convoluted Tubule.
Lots is reabsorbed here. Glucose, amino acids, bicarb and importantly, 65% of passing sodium! It’s already starting early on!
Then we have the loop of Henle! Don’t worry, I won’t go on about the CC multiplier! The descending limb let’s water out but not Na+. Na+ concentration rises.
Then, the opposite occurs in the ascending limb, sodium gets out and water can’t, creating a more dilute urine.
The Distal convoluted tubule continues the trend of the ascending limb, where it’s permeable to sodium but NOT water, so dilution continues and 25% more sodium is reabsorbed.
You get the trend! We hate giving up sodium!
Finally, the collecting duct! There are 2 cell types here. The principal cell reacts to aldosterone, allowing sodium re absorption, in exchange for potassium. The influence of ADH then causes insertion of aquaporin channels, allowing water reabsorption.
Finally, the intercalated cell.
This is influenced by aldosterone, causing reabsorption of potassium, in exchange for hydrogen ions. Acidifying the urine if you like👍
In the next instalment, I will talk about the diuretic drugs and how they work to promote diuresis AND **Natriuresis**
You don’t have to just use furosemide! Everyone’s favourite loop…
Let’s use our physiology and pharmacology knowledge to combine some of them, to achieve good natriuresis as well as diuresis👍👏🤷♂️
Starting:
1/3 Carbonic anhydrase inhibitors.
Acetazolamide being one.
Good for the alkalotic, fluid overloaded patient, (as many ICU a patients often are). A mild diuresis is achieved with this one, so it’s a good additive choice.en.m.wikipedia.org/wiki/Acetazola…
Where do we scan then?? Linear/curvilinear or phased probe positions shown👍👇
We don’t tend to use linear for the basal sections, as you need depth for the PLAPS points. To see the pleura clearly, minimise depth and drop gain down, you get a real concept of sliding on the screen.
Pleural slide disappears as the parietal and visceral pleura separate. So, a static washing line is seen between the rib pillars 👇. The more you see, the more you recognise. Decompress IF your patient is compromised. It’s more sensitive than CXR!
Probe position shown with marker to right shoulder, left Parasternal edge; roughly at intercostal spaces 2-3/3-4🤷♂️
2/13
What should you see on ultrasound, and the associated sono anatomy🤔
BTW, this is the only basic position you need for this. Dipping the tail or lifting the tail then get you inflow and outflow views. This is more advanced. #FUSIC
3/13
Next, the Parasternal short axis (PSAX) - Mitral view
If you’ve lined up the aortic and mitral valves in the centre of the image on PLAX, a simple rotation of the probe through 90 degrees gives you your view🤛👍
Apply careful firm pressure to displace pesky bowel gas. I start at the umbilicus; you can find the vertebral body easily here. You can then move up or down, tracing the vessel. The aim is to see as much of the vessel as you can. Marker - right (SAX) or to the head (LAX).
3/7
High Subxiphoid SAX
Find that vertebral body shadow again, you will see the aorta and IVC just above this. We are looking for the classic ‘seagull’ sign -
Here we slide the probe along a slug trail of gel, quite crudely, across a wide area of the body. This is often used to ‘window shop’, for structures we can’t see at first. When they snap into view, we can fine-tune movements 👍 Also allows view of larger organs.
3/7
ROCKING
Classic example here is when we get an apical view of the heart. At first, the heart may not be in line with the scan field. We can ‘swing’ it into view, so it appears more square on the screen. Makes parallel measurements more accurate and things less off-axis🤷♂️