Electrolyte Imbalance and Acid-Base disorders

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Electrolyte Imbalance and Acid-Base disorders

• Victor Politi, M.D., FACP,
• Medical Director, St. Johns University
• Dr. Andrew J. Bartilucci Center College of
  Pharmacy and Allied Health Professions, PA Program

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Importance of Homeostasis

• Fluid and electrolyte and Acid-base balance are
  critical to health and well-being
• Maintained by intake and output
• Regulation by renal and pulmonary systems

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Imbalances Result From

• Illness
• Altered fluid intake
• Prolonged vomiting or diarrhea

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Distribution of Body Fluids

• Water is the largest single component of the body
• 60 of adults weight is water
• Healthy people can regulate balance

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Composition of Body Fluids

• Water
• Electrolytes
• Separates into ions when dissolved
• Carries an electrical charge
• Positive charge CATIONS
• Sodium, Potassium, Calcium
• Negative charge ANION
• Bicarbonate, Chloride

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Fluid Intake

• Regulated primarily by thirst mechanism
• In the hypothalamus
• Osmoreceptors monitor serum osmotic pressure
• Hypothalamus stimulated when osmolarlity
  increases
• Thirst mechanism stimulated
• With decreased oral intake
• Intake of hypertonic fluids
• Loss of excess fluid
• Stimulation of renin-angiotensisn-aldosterone
  mechanism
• Potassium depletion
• Psychological factors
• Oropharyngeal dryness

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Fluid Intake (cont)

• Average adult intake
• 2200-2700 cc/day
• Oral 1100-1400
• Solid foods 800-1000
• Oxidative metabolism 300
• By-product of cellular metabolism of ingested
  foods

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Fluid Intake (cont)

• Must be alert
• Able to perceive mechanism
• Able to respond to mechanism
• At risk for dehydration
• Elderly
• Very young
• Neurological disorders
• Psychological disorders

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Fluid Output Regulation

• Kidneys
• Major regulatory organ
• Receive about 180 liters of blood/day to filter
• Produce 1200-1500 cc of urine
• Skin
• Regulated by sympathetic nervous system
• Activates sweat glands
• Sensible or insensible-500-600 cc/day
• Directly related to stimulation of sweat glands
• Respiration
• Insensible
• Increases with rate and depth of respirations,
  oxygen delivery
• About 400 cc/day
• Gastrointestinal tract
• In stool
• Average about 100-200
• GI disorders may increase or decrease it.

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Acid-Base Balance

• pH measures amount of Hydrogen ion concentration
• Greater the concentration, lower the pH
• 7 is neutral lt7 acidic gt7 basic or alkaline
• Needed to maintain cell membrane integrity and
  speed of cellular enzymatic actions
• Normal range 7.35-7.45
• Regulated by buffers

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Physiological Regulation

• Lungs and Kidneys
• Lungs adapt fast
• Try to correct pH before biological buffers kick
  in
• Hydrogen and carbon dioxide levels provide
  stimulus for respirations
• Lungs alter depth and rate according to hydrogen
  concentration
• With metabolic acidosis, respirations increase to
  exhale more carbon dioxide
• Metabolic alkalosis, lungs retain carbon dioxide
  by decreasing respiraitons
• Kidneys take from a few hours to several days
• Reabsorb bicarbonate in case of acid excess
  excrete it in cases of acid deficit

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Common Disturbances Electrolyte Balance

• Sodium
• Hypernatremia (Na gt 145, sp gravity lt 1.010)
• Caused by excess water loss or overall sodium
  excess
• Excess salt intake, hypertonic solutions, excess
  aldosterone, diabetes insipidus, increased s
  water loss, water deprivation
• SS thirst, dry, flushed skin, dry, stick tongue
  and mucous membranes
• Hyponatremia (Na lt 135, sp gravity gt 1.030)
• Occurs with net loss of sodium or net water
  excess
• Kidney disease with salt wasting, adrenal
  insufficiency, GI losses, increased sweating,
  diuretics, SIADH
• SS personality change, postural hypotension,
  postural dizziness, abd cramping, nv, diarrhea,
  tachycardia, convulsions and coma

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Common Disturbances Electrolyte Balance

• Potassium
• Hyperkalemia (K gt 5.3 EKG irregularities-bradycar
  dia, heart block, wide QRS pattern-cardiac
  arrest)
• Primary cause renal failure major symptom
  cardiac irregularity
• Fluid volume deficit, massive cell damage, excess
  K given, adrenal insufficiency, acidosis, rapid
  infusion of stored blood, potassium-sparing
  diuretics
• SS dysrhythmias, paresthesia
• Hypokalemia (K lt 3.5 EKG irregularities-ventricu
  lar)
• Most common electrolyte imbalance affects
  cardiac conduction and function. Most common
  cause potassium wasting diuretics
• Diarrhea, vomiting, alkalosis, excess aldosterone
  secretion, polyruia, extreme sweating, insulin to
  treat diabetic ketoacidosis
• SS weakness, ventricular dysrhythmias,
  irregular pulse

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Common Disturbances Electrolyte Balance

• Calcium
• Hypercalcemia (Ca gt 5 x-rays show calcium loss,
  cardiac irregularities)
• Frequently symptom of underlying disease with
  excess bond resorption and release of calcium
• Hyperparathyroidism, malignant neoplastic
  disease, Pagets disease, Osteoporosis, prolonged
  immobization, acidosis
• SS anorexia, nausea and vomiting, weakness,
  kidney stones
• Hypocalcemia (Ca lt 4.0, EKG abnormalities)
• Seen in severe illness
• Rapid blood transfusion with citrate,
  hypoalbuminemia, hypoparathyroidism, Vitamin D
  deficiency, Pancreatitis, Alkalosis
• SS numbness and tingling, hyperactive reflexes,
  positive Trousseaus sign (wrist), positive
  Chvosteks sign (cheek), tetany, muscle cramps,
  pathological fracture

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Common Disturbances Electrolyte Balance

• Chloride
• Usually seen with acid-base imbalance
• Hyperchloremia (Na gt145, Bicarb lt22)
• Serum bicarbonate values fall or sodium rises
• Hypochloremia (pH gt 7.45)
• Excess vomiting or N/G drainage loop of thiazide
  diuretics because of sodium excretion
• Leads to metabolic alkalosis due to reabsorption
  of bicarbonate to maintain electrical neutrality

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Acid Base Balance

• Arterial blood gas is best measure
• pH
• Measures hydrogen ion concentration
• 7.35-7.45
• PaCO2
• Measures carbon dioxide (pulmonary ventilation)
• 35-45 lt hyperventilation gt
  hypoventilation
• PaO2
• Oxygen in arterial blood
• 80-100
• Oxygen Saturation
• How much hemoglobin is carrying oxygen
• 95-99
• Base Excess
• How much blood buffer is present
• High alkalosis Caused from Antacids, rapid
  blood transfusion, IV bicarb
• Low acidosis Caused from Diarrhea
• Bicarbonate
• Major renal component of acid-base balance

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Common Disturbances in Acid-Base Balance

• Respiratory acidosis (pH lt7.35 CO2gt 45)
• Increased carbon dioxide, excess carbonic acid,
  increased hydrogen ion concentration
• Causes HYPOVENTILIATION
• Atelectasis, pneumonia, cystic fibrosis,
  respiratory failure, airway obstruction, chest
  wall injury, overdose, paralysis of respiratory
  muscles, head injury, obesity
• SS neurological changes and respiratory
  depression
• Confusion, dizziness, lethargy, headache,
  ventricular dysrhythmias, warm flushed skin,
  muscular twitching

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Common Disturbances in Acid-Base Balance

• Respiratory alkalosis (pH gt 7.45 CO2 lt 35)
• Decreased carbon dioxide, decreased hydrogen
  ions
• Causes hyperventilation
• asthma, pneumonia, inappropriate ventilator
  settings, anxiety, hypermetabolic state, CNS
  disorder, salicylate overdose
• SS dizziness, confusion, dysrhythmia,
  tachypnea, numbness and tingling, convulsions,
  coma

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Common Disturbances in Acid-Base Balance

• Metabolic acidosis (pH lt 7gt35 Bicarb lt 22)
• Increased acid (hydrogen ions, decreased sodium
  bicarbonate
• High Anion Gap (Sodium minus Chlorine Bicarb)
• Causes starvation, diabetic ketoacidosis, renal
  failure, lactic acidosis, drug use (paraldehyde,
  aspirin)
• SS tachypnea with deep respirations, headache,
  lethargy, anorexia, abdominal cramps

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Common Disturbances in Acid-Base Balance

• Metabolic alkalosis
• Loss of acid (hydrogen ions) or increase
  bicarbonate
• Most common cause vomiting and gastric
  secretions
• Hypokalemia, hypercalcemia, excess aldosterone,
  use of drugs (steroids, bicarb, diuretics)
• SS numbness and tingling, tetany, muscle cramps

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Assessing Blood Gases

• 1st look at pH
• Over 7.45 Alkalosis
• Below 7.35 Acidosis
• 2nd check CO2
• Should move in opposite direction as pH
• if abnormal, respiratory cause
• if normal, metabolic
• 3rd evaluate bicarbonate
• Should move in same direction as pH
• If so, metabolic cause
• if not, respiratory cause
• 4th both CO2 and bicarbonate abnormal?
• Which more closely corresponds to pH and deviates
  more from normal?
• Shows likely cause, other is trying to compensate

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Hypercalcemia
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Hypercalcemia

• Most common causes (90 of cases)
• Malignancy associated hypercalcemia
• Tumor production of PTH-related protein is the
  commonest paraneoplastic endocrine syndrome,
  accounting for most cases of hypocalcemia in
  inpatients
• Primary hyperparathyroidism
• Most common cause in ambulatory patients

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Hypercalcemia - symptoms

• Symptoms
• (usually occur if serum calcium is gt 12mg/dl and
  tend to be more severe if hypercalcemia develops
  acutely)
• Constipation
• Polyuria
• Heart
• Ventricular extrasystoles and idioventricular
  rhythm
• Neurologic symptoms
• Stupor, coma, azotemia in severe cases

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Hypercalcemia - TX

• Treatment
• Ultimate goal locate primary disease process
  control
• Treatment of hypercalcemia of malignancy
• Bisphosponates effective in 95 of cases
• Emergency tx of choice
• Saline furosemide (prevent volume overload and
  enhances Ca2 excretion)

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Hypocalcemia
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Hypocalcemia

• Often mistaken as a neurological disorder
• Most common cause
• renal failure
• Other causes
• Malabsorption
• Vitamin D deficit
• Alcoholism
• Diuretic therapy
• Endocrine disease

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Hypocalcemia - Symptoms

• Hypocalcemia increase excitation of nerve and
  muscle cells, primarily affecting the
  neuromuscular and cardiovascular systems

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Hypocalcemia - Symptoms

• Symptoms
• Muscle cramps and tetany
• Laryngospasm w/stridor
• Convulsions
• Paresthesias of lips extremities
• Abdominal pain

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Hypocalcemia - Symptoms

• Chvosteks Trousseaus signs are usually
  readily elicited
• Chvosteks sign
• Contraction of the facial muscle in response to
  tapping the facial nerve anterior to the ear
• Trousseaus sign
• Carpal spasm occurring after occlusion of the
  brachial artery with a bp cuff for 3 minutes

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Hypocalcemia - Labs

• ECG
• Prolonged QT interval
• Serum calcium concentration
• lt 9mg/dl
• Serum magnesium
• usually low
• Serum phosphate level
• usually elevated in hypoparathyroidism or
  end-stage renal failure
• Suppressed in early stage renal failure or
  vitamin D deficiency

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Hypocalcemia - Tx

• Severe, symptomatic hypocalcemia
• 10-15 milligrams of calcium per kilogram of body
  weight, or 6-8 10-ml vials of 10 calcium
  gluconate (558-744mg of calcium) added to 1 liter
  of D5W and infused over 4-6hrs. Adjust infusion
  rate to maintain serum calcium level at
  7-8.5mg/dL
• In presence of tetany, arrhythmias or seizures
• Calcium gluconate 10 (10-20 ml) IV over 10-15min

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Hypocalcemia - Tx

• Asymptomatic Hypocalcemia
• Oral calcium 1-2g and vitamin D preparations are
  used

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Hyperkalemia
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Hyperkalemia

• Many cases associated with acidosis
• Pseudohyperkalemia result of lysis of red cells
  releasing potassium into the serum

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Hyperkalemia

• Associated With
• HIV
• diabetic ketoacidosis
• Medications
• Surgical Med - Aminocaproic acid
• Ace Inhibitors
• Trimethoprim
• Immunosuppressive medications

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Hyperkalemia

• Findings
• Muscle weakness
• Abdominal distention
• Diarrhea
• Rare finding flaccid paralysis

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Hyperkalemia

• Heart rate may be slow, V-Fib cardiac arrest
  may occur
• ECG changes include
• Peaked T waves, widening of QRS, biphasic QRS-T
  complexes
• Notenearly 50 of cases with serum levels
  6.5meq/L or greater will not exhibit ECG changes

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Hyperkalemia - TX

• Confirm elevated level of serum potassium
  (measure in plasma rather than serum)
• Tx consists of witholding potassium and giving
  cation exchange resins by mouth or enema
• Sodium polystyrene sulfonate 40-80g/d

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Hyperkalemia Emergent TX

• Indicated if cardiac toxicity or muscular
  paralysis present or if hyperkalemia severe gt
  6.5-7 meq/L
• Calcium gluconate 10 5-30ml IV
• NaHCO3 44-88 meq (1-2 ampules) IV
• Insulin 5-10 units, IV plus glucose 50 25g,1
  ampule, IV
• Nebulized albuterol 10-20mg in 4 ml normal saline
  inhaled over 10 min

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Hyperkalemia Nonemergent Tx

• Loop diuretic (Furosemide) 40-160mg IV or orally
  w or w/o NaHCO3, 0.5-3 meq/kg daily
• Sodium polystyrene sulfonate (Kayexalate) oral
  15-30g in 20 sorbitol (50-100mL) rectal 50g in
  20 sorbitol
• Hemodialysis
• Peritoneal Dialysis

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Hypokalemia
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Hypokalemia

• Severe hypokalemia may induce dangerous
  arrhythmias or rhabdomyolysis
• Self limited hypokalemia occurs in 50-60 of
  trauma patients (possibly related to enhanced
  release of epinephrine)
• Hypokalemia in the presence of acidosis suggests
  profound potassium depletion and requires urgent
  tx

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Hypokalemia - Signs

• Common findings
• Muscular weakness
• Muscle cramps
• Fatigue
• Constipation or ileus

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Hypokalemia - Labs

• ECG
• Decreased amplitude
• T wave broadening
• Prominent U waves
• PVCs
• Depressed ST segment

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Hypokalemia Causes

• Several Causes of Hypokalemia
• Decreased potassium intake
• Potassium shift into the cell
• Renal potassium loss
• Primary hyperaldosteronism
• Renovascular HTN
• Cushings Syndrome
• Bartters Syndrome
• Metabolic acidosis
• Extrarenal potassium loss
• Vomiting, diarrhea, laxative abuse,
• Zollinger-Ellison syndrome

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Hypokalemia- Tx

• Mild to moderate deficiency
• Oral potassium
• 20 meq/L to prevent hypokalemia,
• 40-100 meq/L over a period of days to weeks to
  treat hypokalemia and fully replete potassium
  stores

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Hypokalemia - TX

• Moderate to severe
• Peripheral IV should not exceed 40meq/L at rates
  up to 40 meq/L/h
• Continuous ECG monitoring indicated
• Check serum potassium q 3-6 hours
• Correct magnesium deficiency

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Hyponatremia
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Hyponatremia

• MILD HYPONATREMIA
• plasma sodium levels under lt135 mmol x L(-1).
• SEVERE HYPONATREMIA
• plasma sodium levels below lt 130 mmol x L(-1)
  compromising health and performance.
• CRITICAL HYPONATREMIA
• plasma sodium levels below 120 mmol x L(-1) (may
  be fatal).

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Hyponatremia

• Defined as serum sodium concentration less than
  130 meq/L
• Most common electrolyte abnormality observed in
  hospitalized patient population
• Most cases of hyponatremia result from water
  imbalance not sodium imbalance.

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Hyponatremia

• Initial approach is to determine serum osmolality
• Normal (280-295 mosm/kg)
• Low (lt 280 mosm/kg)
• High (gt 295 mosm/kg)

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Hyponatremia

• Measurement of urine sodium helps distinguish
  renal from non-renal causes
• Urine sodium gt 20 meq/L
• consistent with renal salt wasting (diuretics,
  ACE inhibitors, mineralocorticoid deficiency,
  salt-losing nephropathy)
• Urine sodium lt 10meq/L or fractional excretion of
  sodium lt 1
• implies sodium retention by kidney to compensate
  for extrarenal fluid loss (vomiting, diarrhea,
  sweating, third-spacing)

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Hyponatremia

• Isotonic Hypertonic hyponatremia can be ruled
  out by determining serum osmolality, blood
  lipids, and blood glucose
• Osmolality 2 (Na meq/L)
• Glucose mg/dL BUN mg/dL
• 18 2.8

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Hypotonic hyponatremia
Volume Status
Hypervolemic
Hypovolemic
Euvolemic

• Edematous states
• CHF
• Liver Disease
• Nephrotic syndrome (rare)
• Advanced renal failure

• UNa lt 10meq/L
• Extrarenal salt loss
• Dehydration
• Diarrhea
• Vomiting

1. SIADH 2. Post-op hyponatremia 3.
Hypothyroidism 4. Psychogenic polydipsia 5. Beer
potomania 6. Idiosyncratic drug reaction 7.
Endurance exercise

• UNagt 20meq/L
• Renal salt loss
• Diuretics
• Ace inhibitors
• Nephropathies
• Mineralocorticoid deficiency
• Cerebral sodium wasting syndrome

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Hyponatremia - Tx

• Treatment of underlying condition
• Water restriction
• Diuretics
• Hypertonic 3 saline
• Dangerous in volume
  overloaded states, not
  routinely recommended
• Emergency dialysis

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Hypernatremia
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Hypernatremia

• Na gt 145, sp gravity lt 1.010
• An intact thirst mechanism usually prevents
  hypernatremia
• Excess water loss can cause hypernatremia only
  when adequate water intake is not possible, as
  with unconscious patients
• Rarely, excessive sodium intake may cause
  hypernatremia

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Hypernatremia - Symptoms

• Typical Findings include
• orthostatic hypotension, oliguria
• In severe cases
• hyperthermia, delirium, and coma

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Hypernatremia- TX

• Treatment directed at correcting the cause of
  fluid loss and replacing water and as needed,
  electrolytes
• If hypernatremia is corrected too rapidly, the
  osmotic imbalance may cause water to
  preferentially enter brain cells causing cerebral
  edema and potentially severe neurologic impairment

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Questions ?