Electrolyte + Acid base Disorders Flashcards
Causes of Hypernatremia
(1. ) Water loss
- Dehydration
- Diuretics
- DI
- Osmotic diuresis e.g. HHS
- Diarrhoea/ Vomiting/ Sweating/ Burns
(2. ) Excessive hypertonic fluid
- IV infusion
- Total parental nutrition
- Enteral feeds (NGT)
Signs + syx of Hypernatremia
- Lethargy
- Weakness
- Confusion
- Agitation
- Seizure
- DI: polydipsia, polyuria, thirst
Ix and Mx of Hypernatremia
Ix: UE, Ca, Glucose
Mx: PO or IV fluids
Cause of HYPOnatremia
Caused by water excess or sodium depletion
(1. ) Hypovolaemic hyponatremia
- Diuretic therapy
- Addison’s: inadequate steroids and thus Na resorption
- Burns/diarrhoea/ vomiting - body loses electrolytes + water
(2. ) Euvolemic
- Hypothyroidism
(3. ) Hypervolemic hyponatremia
- SIADH: too much ADH release, too much water reabsorbed so serum Na drops
- HF, kidney, liver disease, causes fluid to accumulate in body which dilutes Na in body
- Hypalbuminaemia
- Nephrotic syndrome
Presentation of HYPOnatremia
- Asyx (particularly if developed slowly or mild)
- Lethargy
- Headache
- Dizziness
- Postural hypotension
- Ataxia
- Severe changes: confusion/psychosis/seizures
Hx/Ex/Ix of HYPOnatremia
Hx:
- Any recent illness e.g. gastroenteritis
- PMH: any chronic illnesses such as anorexia nervosa, HF, CKD
- DH: thiazides, steroids?
Ex
- Determine volume status
- Assess HR, postural change in BP, JVP, oedema, signs of dehydration - dry skin/mucous mb/low uo/reduce skin tugor
- Ask about fluid intake and inspect them
- Are they dehydrated/euvolemic/oedematous ?
Ix
(1. ) Serum Na and osmolarity
(2. ) Urine Na or osmolarity
(3. ) Further ix if necessary:
- Urinalysis - if renal disease
- TFT
- Serum cortisol, ACTH - if AI
- BNP - if HF
- LFT
Mx of HYPOnatremia
Admit if:
- Acute onset or severe Na (<125)
- Syx: CNS disturbance, confusion, headache, drowsiness, coma/altered GCS, seizures
- Signs of hypovolaemia
Mx
(1. ) Rx underlying cause e.g. medication, AI, dehydration
(2. ) Hypertonic 1.8% saline (slow inc as rapid inc can lead to Central pontine Myelinolysis)
If not severe, assess fluid status and Rx accordingly
(1. ) Correct underlying cause
(2. ) Hypovolaemia: 0.9% saline cautious rehydration
(3. ) Hypervolaemia: fluid restriction
(4. ) SIADH: Tolvaptan
What is SIADH? Causes? Mx?
Inappropriate ADH secretion from pituitary or ectopic source, despite low serum osmolality.
Causes:
- Small cell lung ca – tumour produced ADH
- Atypical pneumonia (legionella)
- Brain damage: meningitis, SAH, Head injury, tumour,
- Medications: Carbamzepine, ssri
Management
- Restrict fluid intake
- Rx underlying cause
- Tolvaptan (competitive ADH-R antagonist, so prevent ADH binding)
- If severe hyponatremia: Hypertonic IV fluid
Hyperkalaemia: causes, presentation
Causes:
- Kidney: AKI, CKD
- Rhabdomyolysis
- Addison’s
- Medication: aldosterone antagonists, ACEi, NSAIDs, K+ supps
Presentation
- Asyx
- Weakness
- Tingling
- Nauseous
- Severe/sudden hyperkalaemia: palpitations, SoB, CP, N+V
Hyperkalaemia: Ix, Mx
Investigations
(1. ) VBG
(2. ) UE
(3. ) ECG
- Tall, peaked T waves
- Flat or absent P waves
- Broad QRS
- VF
Management >6.5mmol +/- ECG changes - urgent Rx (1.) IV Calcium gluconate (2.) IV insulin + glucose/dextrose (3.) Nebulised SABA (4.) UE + ECG monitoring (5.) Check any precipitating factors + lower total body K via: - Ca resonium = prevent K gut absorption so excreted into stools - Loop diuretics - Dialysis
Non-urgent/ <6mmol K
(1. ) Change in diet
(2. ) Review medication e.g. stop spironolactone or acei
Hypokalaemia: causes, presentation
Causes
- Renal: diuretics, Cushing, hyperaldosteronism, hypomagnesium
- extra-renal: inadequate oral intake, D+V, alkalosis, burns, excessive sweating
Presentation
- Asyx
- Severe: Weakness, paraesthesia, hypotonia, hyporeflexia, tetany
Hypokalaemia: Ix + mx
Ix
(1. ) ECG
(2. ) Blood: UE, Cl, HCO3, glucose, mg, ca
(3. ) VBG
Mx Mild (>2.5, no ECG change, pt can tolerate oral) (1.) Oral supps (SandoK) (2.) Rx cause (3.) Check UE/K+ 3d after
Severe (<2.5)
(1. ) Cardiac, electrolyte, mg monitoring
(2. ) IV 0.9% saline
(3. ) IV K+ 20mmol/h
(4. ) Rx cause
Hypomagnesium causes + presentation + ix + mx
Causes
- Drugs: PPI, diuretics
- Alcoholism
- Refeeding syndrome
- Parental nutrition
- Severe burns
- Dec gut absorption: D+V, malabsoprtion (crohns, coeliac), SMALL BOWEL RESECTION***
- Acute pancreatitis
Presentation
- asyx
- hypocalcemia syx: Tetany, Trousseau and Chvostek signs, paraesthesia
- seizure
- arrythmia
Ix
(1. ) ECG
(2. ) Serum Mg, Ca, K, PO, glucose
(3. ) 24-hour Mg excretion
Mx
(1. ) Identify and Rx cause e.g. medication
(2. ) IV Mg replacement if <0.4 /tetany/ arrhythmias /seizures
(3. ) PO Mg salts if >0.4
Resp acidosis - what would you seen in ABG, causes?
Resp acidosis: Lo pH, hi CO2
Causes
- Asthma, COPD - Raised HCO3 indicates pt has been retaining CO2 chronically usually seen in COPD.
- Respiratory depression e.g. opiates, benzodiazapams
- Guillain-Barre syndrome – inability to ventilate due to paralysis
Resp alkalosis- what would you seen in ABG, causes?
Resp alkalosis: Hi pH, lo CO2
Anything causes hyperventilation + RR is high as they are blowing off CO2.
Causes:
- Anxiety
- PE - to differentiate between the two PE would also have a lo O2.
- Salicylate poisoning
- Altitude
- Pregnancy
- Pyrexia
