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Roma, 7-9 novembre 2014
Meet the expert - Ipernatremia
Marco Faustini Fustini IRCCS Istituto delle Scienze Neurologiche di Bologna (ISNB)
Ospedale Bellaria [email protected]
Roma, 7-9 novembre 2014
Relazione a forma di U tra la [Na+] nel plasma al ricovero e la mortalità in ospedale1
Adattato da: Wald R, et al. Arch Intern Med. 2010;170(3):294-302.
[Na+] nel siero al ricovero mEq/L
Prob
abili
tà p
rede
tta d
ella
m
orta
lità
in o
sped
ale
110 115 120 125 130 135 140 145
0.05
0.10
0.15
0.20
n=53.236
Curva cubica restrittiva
Intervallo di confidenza 95%
Wald, R. et al. Arch Intern Med 2010;170:294–302.
Roma, 7-9 novembre 2014
Hypernatraemia
Hypernatraemia (serum sodium > 145 mmol/L) is a hype-osmolar disorder, in which there is a deficit of body water relative to body solutes.
Hypernatraemia is always synonymous with
hyperosmolality, because Na+ is the main constituent of plasma osmolality,
but hyperosmolality can exists without hypernatraemia when there is an excess of non-sodium solute. This occurs most often with marked elevation of plasma glucose, as in patient with non-ketotic hyperglycaemic hyperosmolar coma.
Verbalis J 2003
Roma, 7-9 novembre 2014
Durante la visita medica in reparto ti viene chiesto quale soluzione usare in un paziente “disidratato”
• A) Soluzione salina 0.9% (“fisiologica”) • B) Soluzione glucosata 5% • C) Soluzione salina 0.45% • D) Soluzione ipertonica 3% • E) Ringer lattato • F) Soluzione elettrolitica “reidratante”
Roma, 7-9 novembre 2014
Durante la visita medica in reparto ti viene chiesto quale soluzione usare in un paziente “disidratato”
• A) Soluzione salina 0.9% (“fisiologica”) • B) Soluzione glucosata 5% • C) Soluzione salina 0.45% • D) Soluzione ipertonica 3% • E) Ringer lattato • F) Soluzione elettrolitica “reidratante”
1) Una delle soluzioni elencate, indifferentemente 2) Una delle soluzioni elencate, tranne la soluzione ipertonica 3) Una delle soluzioni elencate, tranne la soluzione glucosata 5% 4) Non so
Roma, 7-9 novembre 2014
Revisiting dehydration:
what a difference a word makes
Roma, 7-9 novembre 2014
Dehydration vs. (extracellular fluid) volume depletion
• The terms dehydration and volume depletion are used interchangeably at the bedside.
• This habit may be pernicious, because the two conditions describe clearly different disturbances.
• The proper use of the terms dehydration and volume depletion should improve patient care.
• Dehydration associated with hypertonicity = a principal loss of body water from the intracellular and interstitial compartments.
• Extracellular fluid volume depletion = a fluid deficiency that clinically affects the vascular tree.
N Engl J Med 1977 297: 1444 J Clin Invest 1958 37: 1236 N Engl J Med 1962 267: 77 Science 1952 115: 447
Roma, 7-9 novembre 2014
Body fluid compartments in man
J Verbalis, 2003
Volemia
EABV Intravascular fluid
Roma, 7-9 novembre 2014
Dehydration vs. (extracellular fluid) volume depletion
• The physiologic concept of dehydration, at first glance, might subsume the definition of volume depletion.
• This erroneous assumption, made by investigators about
seventy years ago, was corrected by physiologists in the era after World War II, but today has insidiously resurfaced because volume depletion has become a shorthand for extracellular fluid volume depletion, and the first two words of the latter phrase make all the difference.
N Engl J Med 1977 297: 1444 Ann Intern Med 1997 127 N Engl J Med 1962 267: 77 Science 1952 115: 447
Roma, 7-9 novembre 2014
Dehydration vs. (extracellular fluid) volume depletion
• When water is lost from the skin, gut, or kidney, the hypertonicity created in the ECF is directly transferred to the larger intracellular space.
• Worsening hypertonicity therefore has its biggest impact on the size of the ICF and, to a lesser extent, on interstitial spaces.
• To dehydrate is to lose this intracellular water and stimulate thirst.
N Engl J Med 1977; 297: 1444 Ann Intern Med 1997; 127 N Engl J Med 1962; 267: 77 15: Science 1952; 115: 447
Roma, 7-9 novembre 2014
N Engl J Med 2005
1) Increased plasma osmolality: osmoreceptor stimulation of AVP 2) Decreased arterial circulating volume: decreased effective arterial blood volume (EABV)
Baroreceptor stimulation of AVP
Decreased distal delivery of filtrate to the tip of the loop of Henle
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Physiological relationships among plasma osmolality, plasma AVP concentrations, urine osmolality, and urine volume in man.
Robertson, 1985
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Hypernatremia: clinical manifestations
Infants (outpatients): - hyperpnea, muscle weakness, restlessness, high-pitched cry, insomnia, lethargy, convulsions (rarely), and coma.
Elderly patients (outpatients): - few symptoms until the serum sodium exceeds 160 mmol/L; - thirst, which dissipates as the disorder progresses and is absent in patients with hypodipsia; - muscle weakness, confusion, and coma are sometimes manifestations of coexisting disorders rather than of the hypernatremia itself.
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Hypernatremia: clinical manifestations
In patients of all ages - orthostatic hypotension and tachycardia reflect marked hypovolemia; - rapid sodium loading can cause convulsions and coma.
In hospitalised patients
- clinical manifestations are even more elusive, because they often have preexisting neurologic dysfunction.
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Hypernatremia: clinical manifestations
Brain shrinkage induced by hypernatremia can cause vascular rupture, with cerebral bleeding, subarachnoid hemorrhage, and permanent neurologic damage or death.
Brain shrinkage is countered by an adaptive response that is initiated promptly and consists of solute gain by the brain that tends to restore lost water.
This response leads to the normalization of brain volume and accounts for the milder symptoms of hypernatremia that develops slowly.
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Hypernatremia: clinical manifestations
However, the normalization of brain volume does not correct hyperosmolality in the brain.
In patients with prolonged hyperosmolality, aggressive treatment with hypotonic fluid may cause cerebral edema, which can lead to coma, convulsions, and death.
Recommendation: a 8-10 mmol per liter per day for all patients except those in whom the disorder has developed over a period of hours.
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Caso 1
• Paziente di 8 anni ricoverata per una voluminosa formazione endo e sovrasellare; poliuria e polidipsia da qualche mese; deficit visivo severo (2/10 OD e 3/10 OS). La sodiemia è 142 mmol/L.
• La paziente viene operata per via transfenoidale con rimozione molto ampia della lesione, anche se non radicale. L’esame istopatologico depone per un craniofaringioma adamantinomatoso.
• Nel periodo postoperatorio (nelle prime 48 ore la paziente è trasferita nel reparto di Rianimazione) la paziente non sviluppa poliuria e polidipsia. Tuttavia, si assiste a un progressivo incremento della sodiemia, fino al valore di 159 mmol/L.
Roma, 7-9 novembre 2014
Caso 1
• Trasferita nuovamente nel reparto di Neurochirurgia, la bambina appare polipnoica e agitata.
• Non ci sono segni clinici di deplezione di volume extracellulare. Non c’è edema.
• Il medico di guardia (ore 16) richiede per il giorno successivo un controllo degli esami di routine.
• Il mattino successivo viene eseguito il prelievo venoso. Poco dopo, compare una crisi epilettica.
• La sodiemia (ore 10) è 173 mmol/L.
• Quale potrebbe essere la causa dell’ipernatremia? • Come proponi di agire in questo caso?
Roma, 7-9 novembre 2014
Hypernatraemia – first assessment
Hyper-osmolality Hypertonic hypernatraemia
ECF volume
Normal ECF (loss of free water)
Decreased ECF (loss of free water and sodium: hypotonic solutions)
Increased ECF (gain of free water and sodium: gain of hypertonic solutions)
0.9% saline until vital signs stable, along with free water
free water replacement loop diuretics and free water replacement; hemodialysis if nothing works
Roma, 7-9 novembre 2014 HYPERNATREMIA
Hypernatremia, a deficiency of body water relative to body solute.
Causes: - net water loss; - hypertonic sodium gain
Roma, 7-9 novembre 2014
Causes of hypernatremia: net water loss
Pure water loss: - unreplaced insensible losses (dermal and respiratory) - hypodipsia - neurogenic diabetes insipidus - congenital nephrogenic diabetes insipidus - acquired nephrogenic diabetes insipidus: - renal diseases (medullary cystic disease…) - hypercalcemia or hypokalemia - drugs (lithium, demeclocycline, foscarnet, methoxyflurane,
amphotericin B, vasopressin V2-receptor antagonists) Hypotonic fluid loss:
- renal causes (loop diuretics, osmotic diuresis, postobstructive diuresis, poliuryc phase of acute tubular necrosis…);
- gastrointestinal causes (vomiting, nasogastric drainage, enterocutaneous fistula, diarrhea, osmotic cathartic agents);
- cutaneous causes (burns, excessive sweating)
N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Causes of hypernatraemia: hypertonic sodium gain
- hypertonic sodium bicarbonate infusion - hypertonic feeding preparations - ingestium of sodium chloride - ingestium of sea water - sodium chloride-rich emetics - hypertonic saline enemas - intrauterine injection of hypertonic saline - hypertonic sodium chloride infusion - hypertonic dialysis - primary hyperaldosteronism - Cushing’s syndrome N Engl J Med 2000 342: 1493
Roma, 7-9 novembre 2014
Hypernatremia – first assessment
Hyper-osmolality Hypertonic hypernatremia
ECF volume
Normal ECF (loss of free water)
Decreased ECF (loss of free water and sodium: hypotonic solutions)
Increased ECF (gain of free water and sodium: gain of hypertonic solutions)
0.9% saline until vital signs stable, along with free water
free water replacement loop diuretics and free water replacement; hemodialysis if nothing works
Roma, 7-9 novembre 2014
Mange, K. et. al. Ann Intern Med 1997;127:848-853
Effect of a 1-L Infusion of Water or 0.9% Saline on Virtual Body Fluid Spaces
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Hypernatremia: principles of treatment
• Search the initial cause. • There is no drug for the treatment of
hypernatremia. • Whenever it’s possible, prefer hydration by
mouth (especially in childhood). • Use hypotonic solutions in severe cases, with
caution.
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