Hyponatremia - 1. Understanding and Working the Problem

Описание: This is the first tutorial in a short series on hyponatremia. About 15% of our critical care patients has a problem with dysnatremia -- high or low sodium levels in plasma. Hyponatremia, with symptoms, is a medical emergency as it can result in cerebral edema and irreversible brain injury.
In this tutorial I first present two case of hyponatremia - one that needs to be treated emergently and one that does not, despite both having the same plasma sodium levels. I then proceed to discuss the physiology of sodium and why it is a key component of body osmolality.
The main part of the tutorial is developing a decision tree for working the hyponatremic problem. The key question is whether this is hypotonic or non hypotonic hyponatremia. If it is non hypotonic you need to look for other sources of unmeasured osmoles (usually alcohols).
Hypotonic hyponatremia may be associated with myriad problems - but your main concern is whether or not this is being caused by kidney injury or blockade or normal renal pathways (e.g. diuretics). Ultimately I provide an algorithm for how to make a firm diagnosis of the cause of hyponatremia.
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Contents
00:13 Introduction
00:52 Clinical Scenarios
01:53 Dysnatremias and Extracellular Osmolality
03:22 Understanding the Osmolality of Extracellular Fluid (why Sodium is important)
04:46 Electrochemistry and Osmolarity
05:38 Calculating Osmolarity
06:21 How Rapid Falls in Serum Osmolality Impacts the Brain
10:06 Hypertonic Saline
14:00 Hyponatremia - How to Work the Problem
14:19 You Must Send 4 Tests
14:48 Measure Blood Glucose
15:34 Measure Serum and Urinary Osmolality and Urinary Sodium
16:13 Why Urinary Osmolality is Important
19:50 Why Urinary Sodium is Important
21:00 Algorithm Part 2 - Urinary Osmolality (ADH)
21:53 Part 3 - Serum Osmolality
22:35 Part 4 - Look for and Osmol Gap
24:15 Hypotonic Hyponatremia
24:35 Step 5 - Urinary Sodium (plasma urea and creatinine) - Are the Kidneys Working?
27:26 All the Steps in a Single Algorithm
29:24 Review, End and Preview