Thread by @JanaSharara

1/🧵Hey #MedTwitter #NephTwitter: 📣 #Tweetorial alert 🚨
DDAVP clamp in #Hyponatremia ❗️
Let’s go for a ride 🚌 and discover together starting with a case!
79 yo female👵🏽 presents with nausea, vomiting and decreased level of consciousness.
Her labs showed a serum Na=109mmol/L

2/🧵 Isotonic NaCl 🧂 solution was administered and 24 hrs later, her neurological 🧠 symptoms worsened (new hypotonia, tremors and involuntary muscle spasms) . What is happening with our patient?

3/🧵These are complications from overcorrection of the hyponatremia!!
Other findings may include: AMS, dysarthria, dysphagia, seizures, confusion or lethargy. 😩😣🥱

4/🧵 Before we go into the management and prevention of overcorrection of hyponatremia, let’s first establish why we want to fix it. 🤔
Why is Hyponatremia important clinically⁉️

5/🧵 The answer is all of the above!
Acute hyponatremia (<48h) is associated with a mortality ≥50% in hospitalized patients (serum Na < 120). Unless you see the acute drop, most hyponatremias are managed as chronic. ⏳

PMID: 21441132, 34414205, 25364669, 29295830

6/🧵Rapid correction of chronic hyponatremia may cause osmotic demyelination syndrome: may be permanent.
ODS occurs when sodium increases too rapidly & outpaces brain’s ability to recapture lost organic osmolytes. It can occur even at rates of change >8 mEq/dL
PMID: 34414205

7/🧵 Inadvertent overcorrection of chronic hyponatremia is quite common due to the unexpected emergence of water diuresis.

Hence, prevention of overcorrection to reduce the risk of osmotic demyelination syndrome are a hotspot for discussion. 🔥

8/🧵 One means of prevention is the DDAVP clamp 🗜

Other means of managing overcorrecting hyponatremia are rescue and reactive..

Check @kkalra_22 ‘s tweetorial for more details.

https://twitter.com/kkalra_22/status/1262852274772152321?s=20&t=HB5_CDrDAs0VcKtnMtP7ug

9/🧵 In order to understand the DDAVP clamp🗜, we will focus on the denominator of the simplified Edelman's equation.

It states that plasma sodium equals the total body exchangeable sodium and potassium divided by total body water 💦

PMID: 13575523

10/🧵 To illustrate our point, let’s use a case. Which hyponatremic patient is the most appropriate candidate for DDAVP clamp?

11/🧵 Our Hypovolemic patient!

Patients at risk of rapid sodium overcorrection due to a sudden drop in ADH (and subsequent water diuresis) are great candidates for a DDAVP clamp ❗️🗜

12/🧵Specifically patients with appropriate ADH excess such as in hypovolemia because a state of ADH excess is commonly-encountered in hyponatremia.

But is this appropriate (i.e. hypovolemia) or inappropriate (i.e. SIADH)? 🤔

13/🧵In states of hypovolemia, after volume resuscitation→ ADH levels would plummet and vasopressin is shut off → emergence of water diuresis → kidneys excrete a ton of free water.
Translation: Our denominator is in danger!
PMID: 26031887

14/🧵 How can we avoid a diminution of our denominator⁉️

We can give back free water (although depending on UOP may be difficult to titrate and keep up!)

Or we can prevent the denominator from dwindling with DDAVP clamp! 🗜😏

15/🧵 Replacing free water excreted from the kidney could be with IV 5% dextrose.
This requires careful attention to UO & serum Na, with titration of the D5W (can be challenging when UO > 200 cc/hr), but depending on the polyuria & renal function, you may not be able to keep up!

16/🧵However, a preventative/proactive approach will not allow excessive water excretion by “clamping” 🗜 the kidneys with DDAVP, typically 2 mcg IV q8hr.
DDAVP stimulates the V2-vasopressin receptors in the kidney, causing renal retention of water. 💦
PMID: 23266328, 26031887

17/🧵 Typical strategy includes DDAVP every 6-8 hrs with a slow infusion of hypertonic saline, and titrating the doses to have a controlled rise in serum Na, usually ~ 6 mmol/L/day. 🧂

PMID: 23266328, 26031887

18/🧵 ❌❌❌Contraindications to proactive DDAVP clamp:
-inability to control oral fluid intake (must be able to restrict)
-patients with pure hypervolemic hyponatremia (e.g. heart failure, cirrhosis) due to fluid overload

19/🧵 The DDAVP clamp is a powerful tool for severe hyponatremia.
It is the most definitive approach to controlling sodium. 🧂
Observational data &small trials support its use in select populations (ICU pts, pts with Na<120.) [PMID: 23266328, 24262506],however there are no RCTs

20/🧵 Hope you feel more comfortable on
🗜How to rx DDAVP clamp
👵🏽Who is eligible for DDAVP clamp
🎯The purpose of the clamp

21/🧵Thank you for reading, until next time, stay hydrated 💦and protect your kidneys!
Special thanks to @Nephro_Sparks @DrFlashHeart @TheBeaniac @menonshina @ghobby @Elena_Cervants @amyaimei @brian_rifkin @bilalksheikh and of course @NSMCInternship 🤍