Electrolyte imbalances.docx

**Hypovolaemia** **Hypervolaemia** **What** [Loss] of sodium and water (ECF loss) [Gain] of sodium and water (ECF gain) **Cause** Blood loss, internal fluid loss, diuretics, sweating, vomiting Excessive isotonic IV, Na retention (CHF, primary hyperaldosteronism) **Clinical** Signs: low JVP,...

**Hypovolaemia** **Hypervolaemia** **What** [Loss] of sodium and water (ECF loss) [Gain] of sodium and water (ECF gain) **Cause** Blood loss, internal fluid loss, diuretics, sweating, vomiting Excessive isotonic IV, Na retention (CHF, primary hyperaldosteronism) **Clinical** Signs: low JVP, low urine output Tests: high albumin, urea and haematocrit Signs: high JVP, peripheral and pulmonary oedema/crepitations, SOB, ascites, **Physiological response** 1. Baroreceptors release of ADH. JGA RAAS 2. Water retention and Na reabsorption 1. Atrial distension ANP, baroreceptors prostaglandins 2. Natriuresis (Na excretion), diuresis, vasodilation **Treatment** 0.9% NaCl 5% glucose (goes to ICF and ECF) Fluid and salt restriction Diuretics **Impaired Na transport:** **Impaired K transport:** +-----------------------+-----------------------+-----------------------+ | | **Hypokalaemia** | **Hyperkalaemia** | +=======================+=======================+=======================+ | **What** | [Loss] of | [Gain] of | | | potassium (ECF loss) | potassium (ECF gain) | | | \5mmol/L | +-----------------------+-----------------------+-----------------------+ | **Cause** | Redistribution | Lysed cells, | | | (alkalosis), | redistribution | | | diuretics, Conn's | (acidosis, no | | | syndrome, GIT fluid | insulin, beta | | | loss | blockers), renal | | | | retention (reduced | | | | GFR or tubular | | | | secretory failure -- | | | | Addison's, amiloride) | +-----------------------+-----------------------+-----------------------+ | **Clinical** | Signs: skeletal | Signs: skeletal | | | muscle weakness, | muscle paralysis, ECG | | | polyuria, cardiac | changes (peaked T | | | arrythmias and ECG | waves and prolonged | | | changes (t wave | QRS, sine wave | | | height decrease) | pattern), cardiac | | | | arrest | +-----------------------+-----------------------+-----------------------+ | **Physiological | More negative | Less negative | | response** | transmembrane | transmembrane | | | potential | potential excessive | | | hyperpolarisation and | depolarisation and | | | then enhanced | then reduced | | | excitability | excitability | | | | | | | With dehydration | Aldosterone | | | involved, aldosterone | | | | acts to increase Na | 1. Adrenal zona | | | reabsorption and | glomerulosa | | | excrete more K, | releases | | | making hypokalaemia | aldosterone | | | worse | | | | | 2. Acts on cortical | | | | collecting duct | | | | to reabsorb Na | | | | and excrete K | +-----------------------+-----------------------+-----------------------+ | **Treatment** | Reverse the cause | [Stabilise membrane | | | | potential: | | | KCl (oral or IV) | ] | | | | | | | Amiloride | Ca gluconate or Ca | | | | chloride | | | | | | | | [Shift K into cells: | | | | ] | | | | | | | | Insulin and glucose | | | | | | | | B2 agonist | | | | | | | | Bicarbonate | | | | | | | | [Remove | | | | K:] | | | | | | | | Diuretics | | | | | | | | Resin in gut | | | | | | | | Dialysis | +-----------------------+-----------------------+-----------------------+ **Impaired water transport:** +-----------------------+-----------------------+-----------------------+ | | **Hyponatraemia** | **Hypernatraemia** | +=======================+=======================+=======================+ | **What** | [Loss] of | [Gain] of | | | sodium (low | sodium (high | | | osmolality) | osmolality) | | | | | | | Failure of urine | Failure of urine | | | dilution (too | concentration (too | | | concentrated) | diluted) | | | | | | | 1. With increased | | | | ECF | | | | | | | | 2. With normal ECF | | | | | | | | 3. With decreased | | | | ECF | | +-----------------------+-----------------------+-----------------------+ | **Cause** | CKD, loop or thiazide | Chronic renal | | | diuretics, increased | failure, loop | | | ADH | diuretics, diabetes | | | | insipidus | +-----------------------+-----------------------+-----------------------+ | **Clinical** | Signs: headache, | Signs: confusion, | | | nausea, vomiting, | muscle weakness, | | | seizures, memory | subarachnoid | | | impairment | haemorrhage, central | | | | bleeding (shrinking | | | Note: children more | brain sheering from | | | sensitive than | bone due to tear of | | | elderly | capillary plexus) | +-----------------------+-----------------------+-----------------------+ | **Treatment** | 1. Increased ECF: | Hypotonic solution | | | fluid restriction | | | | | | | | 2. Normal ECF: fluid | | | | restriction | | | | | | | | 3. Decreased ECF: | | | | replace | | | | salt/water | | +-----------------------+-----------------------+-----------------------+