Symptoms 16: Electrolyte Abnormalities

Front 1

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

What is the patients problem list?

Back 1

- Diarrhea
- Vomiting
- Doughy skin
- Feeding difficulty
- Recent travel (Uganda)
- + Sick contact w/ diarrhea
- Sunken fontanel
- Dry mucus membranes
- Tired, fussy

Front 2

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

Differential diagnosis?

Back 2

- Bacterial enteritis: E. coli, etc
- Parasitic enteritis
- Viral: rotavirus
- Metabolic

Front 3

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

What would be the most important study to obtain as your best next step?
a. Complete blood count
b. Electrolytes
c. C reactive protein
d. Urinalysis
e. Blood culture

Back 3

Electrolytes

Front 4

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

What results do you expect for this patient's electrolytes?

Back 4

↑ Na+
↓ K+
↑ Cl-
↓ Bicarb

Front 5

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

Besides measuring this patient's electrolytes, what other labs should you evaluate?

Back 5

- CBC - WBC, Hemoglobin, Hematocrit, Platelets
- Electrolytes - Na+, K+, Cl-, Bicarb
- Glucose
- Stool culture

Front 6

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea
- 6d prior to admission developed non-bloody watery diarrhea (~16x/day) and non-bloody, non-bilious emesis (~3x/day)
- Typically formula fed (3 oz / 3 hrs) but refused for last 3 days
- Supplemented with pedialyte but continues to vomit any PO; only took 3 oz in last 12 hrs
- 1 day prior, became sleepier, less interactive
- Soc Hx: recently returned from 2 week trip to Uganda 1 day prior to onset of sx; mom sick w/ diarrhea 3 days ago, resolved after 24 hours
- Vitals: T - 37°C, HR 120, RR 30, BP 94/60, SaO2 98%
- Exam: fussy, high-pitched cry, skin is warm w/ doughy texture, slightly sunken anterior fontanel

What imaging should you evaluate?

Back 6

KUB (kidneys, ureter, bladder) - normal bowel gas pattern

Front 7

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea

Lab results:
- CBC (WB, hemoglobin, hematocrit, platelets) all normal
- Electrolytes: ↑ Na+ (155), ↓ K+ (3), ↑ Cl- (125), ↓ Bicarb (15)
- Glucose: 102 (slightly elevated)
- Stool culture: + for salmonella
- KUB x-ray: normal bowel gas pattern

What is the diagnosis?

Back 7

Salmonella gastroenteritis with hypernatremic dehydration and normal anion gap metabolic acidosis

Front 8

Case 1:
- 6 mo. old term (no complications) male presents w/ vomiting and diarrhea

Lab results:
- CBC (WB, hemoglobin, hematocrit, platelets) all normal
- Electrolytes: ↑ Na+ (155), ↓ K+ (3), ↑ Cl- (125), ↓ Bicarb (15)
- Glucose: 102 (slightly elevated)
- Stool culture: + for salmonella
- KUB x-ray: normal bowel gas pattern

What are the characteristics of this patient's electrolyte abnormality?

Back 8

Hypernatremic dehydration and normal anion gap metabolic acidosis

Front 9

Case 2:
A 35 year old man complains of profuse watery diarrhea for two days, he is weak and feels faint when he stands from a sitting position. An examination indicates that the man has lost 3 kg of body weight, his tongue is dry and furrowed, and his skin turgor is reduced. Compared to normal values, his plasma sodium concentration is elevated, and his hematocrit is elevated.

What can be concluded about this patient’s body volumes?

a) His intracellular fluid (ICF) volume is increased
b) His extracellular fluid (ECF) volume is increased
c) His total body solute is increased
d) His plasma osmolality is increased
e) His plasma pH is increased

Back 9

(D): Plasma Osmolality is Increased:

- Diarrheal stools contain sodium, potassium, chloride, and bicarbonate.
- The sustained loss of fluid containing the major cation in the ECF will lead to a reduction in ECF volume and is consistent with weakness and faintness when trying to stand.
- The loss of bicarbonate leads to a decrease in plasma pH.
- The elevated plasma sodium concentration indicates that his ECF osmolarity (and therefore ICF osmolarity) is elevated.

Front 10

What are the contents of diarrheal stools?

Back 10

Na+, K+, Cl-, and Bicarb
- Sustained loss of fluid containing the major cation in the ECF will lead to a reduction in ECF volume
- Loss of bicarb leads to decreased plasma pH (metabolic acidosis)
- Elevated plasma Na+ indicates ECF osmolarity (and therefore ICF osmolarity) is increased

Front 11

What is the differential for a patient with hypernatremia?

Back 11

- Pure water loss (diabetes insipidus)
- Hypotonic fluid loss - water depletion exceeding Na+ depletion (vomit / diarrhea)
- Hypertonic Na+ gain (wrong formula preparation)

Front 12

What could cause pure water loss? What would this lead to?

Back 12

Diabetes Insipidus → Hypernatremia

Front 13

What could cause hypotonic fluid loss (water depletion that exceeds Na+ depletion)? What would this lead to?

Back 13

Vomit / diarrhea → Hypernatremia

Front 14

What could cause hypertonic Na+ gain? Would would this lead to?

Back 14

Wrong formula preparation → Hypernatremia

Front 15

What are the symptoms of Hypernatremia?

Back 15

- Irritable, restless, weak, thirsty, vomiting, high-pitched cry, twitching, altered mental status, lethargy, coma, seizures
- Chronic may be asymptomatic
- Doughy skin
- Physical findings may underestimate the degree of dehyration

Front 16

What is "doughy skin" a sign of?

Back 16

Hypernatremia

Front 17

What is "high-pitched cry" a sign of?

Back 17

Hypernatremia

Front 18

What are the major cations in the extracellular space?

Back 18

Na+
Ca2+

Front 19

What are the major cations in the intracellular space?

Back 19

K+
Mg2+

Front 20

What are the major anions in the extracellular space?

Back 20

Cl-
HCO3-
Some protein

Front 21

What are the major anions in the intracellular space?

Back 21

PO4(3-) and organic anions
Protein

Front 22

What is the term for the movement of water across a semi-permeable membrane due to differences in osmolarity (an osmotic pressure gradient)?

Back 22

Osmosis

Front 23

What is the influence of adding isotonic NaCl solutions to the ECF on total body water (TBW), extracellular fluid volume (ECFV), and intracellular fluid volume (ICFV)?

Back 23

Isotonic NaCl solutions:
- ↑ Total Body Water (TBW)
- ↑ Extracellular Fluid Volume (ECFW)
- = Intracellular Fluid Volume (ICFW)

Front 24

What is the influence of adding hypertonic NaCl solutions to the ECF on total body water (TBW), extracellular fluid volume (ECFV), and intracellular fluid volume (ICFV)?

Back 24

Hypertonic NaCl solutions:
- ↑ Total Body Water (TBW)
- ↑ Extracellular Fluid Volume (ECFW)
- ↓ Intracellular Fluid Volume (ICFW)

Front 25

What is the influence of adding hypotonic NaCl solutions to the ECF on total body water (TBW), extracellular fluid volume (ECFV), and intracellular fluid volume (ICFV)?

Back 25

Hypotonic NaCl solutions:
- ↑ Total Body Water (TBW)
- ↑ Extracellular Fluid Volume (ECFW)
- ↑ Intracellular Fluid Volume (ICFW)

Front 26

What type of NaCl solution can increase the intracellular fluid volume (ICFV)?

Back 26

Hypotonic NaCl

Front 27

What type of NaCl solution can decrease the intracellular fluid volume (ICFV)?

Back 27

Hypertonic NaCl

Front 28

What type of NaCl solution causes no change to the intracellular fluid volume (ICFV)?

Back 28

Isotonic NaCl

Front 29

What are the effects of isotonic solutions on cell volume?

Back 29

No change

Front 30

What are the effects of hypertonic solutions on cell volume?

Back 30

Cell shrinks

Front 31

What are the effects of hypotonic solutions on cell volume?

Back 31

Cell swells

Front 32

Which is the following is true regarding treatment of hypernatremic dehydration?

A. The sodium should always be corrected as quickly as possible to prevent ongoing complications
B. All sodium should be removed from the fluids since most cases of hypernatremia are due to excess sodium intake
C. Sodium levels should be repeated every 1-2 days to ensure it is improving
D. Sodium should not be corrected any faster than 0.5mEq/hour since rapid correction can lead to cerebral edema and death

Back 32

Sodium should not be corrected any faster than 0.5mEq/hour since rapid correction can lead to cerebral edema and death

Front 33

What are the goals of treating a patient with hypernatremia?

Back 33

- Restore intravascular volume
- Determine time for correction based on initial sodium concentration (24-72 hours)
- Administer fluids at constant rate over time for correction
- Follow serum concentrations and adjust fluids as needed
- Replace ongoing losses as they occur

Front 34

How do you restore intravascular volume for patients with hypernatremia?

Back 34

Normal saline 20 ml/kg

Front 35

What are the potential complications of hypernatremia?

Back 35

- Severe acute hypernatremia → cerebral contraction → tear cerebral blood vessels, leading to cerebral hemorrhage, seizures, paralysis, and encephalopathy

- Rapid correction of hypernatremia → cerebral edema → encephalopathy, seizures and death

Front 36

What is most commonly the problem in a patient with hypernatremia?

Back 36

Decreased total body water compared to total body sodium

Front 37

What are the most concerning symptoms in patients with hypernatremia?

Back 37

- Neurologic: due to fluid shifts from intracellular to extracellular spaces
- Physical findings may underestimate the degree of dehydration

Front 38

What are the goals of treatment of hypernatremic dehydration?

Back 38

- Restore intravascular volume
- Correct fluid deficit and hypernatremia
- Replace ongoing losses
- In subacute/chronic hypernatremia, Na+ needs to be corrected slowly to prevent cerebral edema

Front 39

Case 3:
- 28-day old male with 7 days of vomiting
- Forceful emesis w/ every feed and seems hungry afterward
- Formula colored, non-bloody, non-bilious
- Stools are soft and mashed potato consistency
- 3 wet diapers/day in past 2 days (normally 6-8 wet diapers/day)
- No fevers at home
- No prior issues w/ vomiting besides "normal baby spit up"
- 3 days ago went to a different ED and discharged w/ diagnosis of viral illness
- No improvement with pedialyte for several days so returned for medical care
- Parents both smoke, does not go to daycare, no sick contacts, no pets, no travel
- HR 162, BP 90/48, RR 32, low weight
- Exam: anterior fontanelle slightly sunken, mucus membranes slightly tacky, oropharynx w/o erythema, decreased radial and pedal pulses (1+), delayed capillary refill (3-4 seconds), all else normal

What is on his problem list?

Back 39

- Poor weight gain
- Cool extremities
- Vomiting
- Delayed capillary refill
- Tachycardia
- Smoke exposure
- Sunken fontanel
- Wide pulse pressure

Front 40

Case 3:
- 28-day old male with 7 days of vomiting
- Forceful emesis w/ every feed and seems hungry afterward
- Formula colored, non-bloody, non-bilious
- Stools are soft and mashed potato consistency
- 3 wet diapers/day in past 2 days (normally 6-8 wet diapers/day)
- No fevers at home
- No prior issues w/ vomiting besides "normal baby spit up"
- 3 days ago went to a different ED and discharged w/ diagnosis of viral illness
- No improvement with pedialyte for several days so returned for medical care
- Parents both smoke, does not go to daycare, no sick contacts, no pets, no travel
- HR 162, BP 90/48, RR 32, low weight
- Exam: anterior fontanelle slightly sunken, mucus membranes slightly tacky, oropharynx w/o erythema, decreased radial and pedal pulses (1+), delayed capillary refill (3-4 seconds), all else normal

What is his differential diagnosis?

Back 40

- Pyloric stenosis
- Infection (bacterial, viral)
- Achalasia
- Metabolic
- TE fistula
- Food intolerance
- Reflux

Front 41

Case 3:
- 28-day old male with 7 days of vomiting
- Forceful emesis w/ every feed and seems hungry afterward
- Formula colored, non-bloody, non-bilious
- Stools are soft and mashed potato consistency
- 3 wet diapers/day in past 2 days (normally 6-8 wet diapers/day)
- No fevers at home
- No prior issues w/ vomiting besides "normal baby spit up"
- 3 days ago went to a different ED and discharged w/ diagnosis of viral illness
- No improvement with pedialyte for several days so returned for medical care
- Parents both smoke, does not go to daycare, no sick contacts, no pets, no travel
- HR 162, BP 90/48, RR 32, low weight
- Exam: anterior fontanelle slightly sunken, mucus membranes slightly tacky, oropharynx w/o erythema, decreased radial and pedal pulses (1+), delayed capillary refill (3-4 seconds), all else normal

What would be the most important study to obtain as your next best step?

Back 41

Electrolytes

Front 42

Case 3:
- 28-day old male with 7 days of vomiting
- Forceful emesis w/ every feed and seems hungry afterward
- Formula colored, non-bloody, non-bilious
- Stools are soft and mashed potato consistency
- 3 wet diapers/day in past 2 days (normally 6-8 wet diapers/day)
- No fevers at home
- No prior issues w/ vomiting besides "normal baby spit up"
- 3 days ago went to a different ED and discharged w/ diagnosis of viral illness
- No improvement with pedialyte for several days so returned for medical care
- Parents both smoke, does not go to daycare, no sick contacts, no pets, no travel
- HR 162, BP 90/48, RR 32, low weight
- Exam: anterior fontanelle slightly sunken, mucus membranes slightly tacky, oropharynx w/o erythema, decreased radial and pedal pulses (1+), delayed capillary refill (3-4 seconds), all else normal

What would you most expect to see on your electrolyte results based on what you know so far?

Back 42

↓ Na+
↓ K+
↓ Cl-
↑ Bicarb

Front 43

Case 3:
- Poor weight gain
- Cool extremities
- Vomiting (7 days)
- Delayed capillary refill
- Tachycardia
- Smoke exposure
- Sunken fontanel
- Wide pulse pressure

Labs:
- ↓ Na+ (133)
- ↓ K+ (3.0)
- ↓ Cl- (95)
- ↑ HCO3- (31.5)
- Normal glucose (78)
- CBC normal (WBC, Hgb, Hct, Platelets)

What imaging should you do?

Back 43

Abdominal X-ray
(normal bowel gas pattern, no free air)

Ultrasound Pylorus
(abnormal pyloric wall thickening and elongation without passage of gastric contents into proximal duodenum, consistent with hypertrophic pyloric stenosis)

Front 44

Case 3:
- Poor weight gain
- Cool extremities
- Vomiting (7 days)
- Delayed capillary refill
- Tachycardia
- Smoke exposure
- Sunken fontanel
- Wide pulse pressure

Labs:
- ↓ Na+ (133)
- ↓ K+ (3.0)
- ↓ Cl- (95)
- ↑ HCO3- (31.5)
- Normal glucose (78)
- CBC normal (WBC, Hgb, Hct, Platelets)

Ultrasound shows abnormal pyloric wall thickening and elongation without passage of gastric contents into proximal duodenum, consistent with hypertrophic pyloric stenosis

What is the diagnosis? Include electrolyte abnormalities?

Back 44

Dehydration with hypochloremic, hypokalemic metabolic alkalosis from pyloric stenosis

Front 45

Compared to normal conditions, a partially compensated metabolic acidosis is characterized by ________ pH values, _________ plasma bicarbonate concentrations, and _________ pCO2 values in the extracellular fluids.

a. decreased, decreased, decreased
b. decreased, normal, increased
c. decreased, increased, normal
d. decreased, decreased, increased
e. decreased, increased, increased

Back 45

- ↓ pH
- ↓ Plasma Bicarb
- ↓ pCO2

- Compared to normal, acidosis is characterized by decreased pH
- Primary metabolic acidosis is due to an increase in acid or loss of base; the result is decreased plasma bicarbonate
- The respiratory compensation to metabolic acidosis is to increase ventilation, leading to a decrease in arterial pCO2

Front 46

What is the initiating change in respiratory acidosis?

Back 46

↑ PCO2

Front 47

What is the initiating change in respiratory alkalosis?

Back 47

↓ PCO2

Front 48

What is the initiating change in metabolic acidosis?

Back 48

↓ HCO3-

Front 49

What is the initiating change in metabolic alkalosis?

Back 49

↑ HCO3-

Front 50

What is a normal pH? [H+]? PCO2? [HCO3-]?

Back 50

- pH: 7.4
- [H+]: 40 nEq/L
- PCO2: 40 mmHg
- [HCO3-]: 24 mEq/L

Front 51

How common is pyloric stenosis? Who is most likely to have it?

Back 51

- Rare (0.2-0.35%)
- More common in males
- 30% of cases are in first-born children

Front 52

When do symptoms usually begin for a patient with pyloric stenosis?

Back 52

3-5 weeks of age

Front 53

What is the classic presentation of pyloric stenosis?

Back 53

- 3-6 week old infant
- Immediate post-prandial non-bilious and projectile emesis
- Appears hungry after vomiting
- Poor weight gain and dehydration
- Occasionally an olive-like mass is palpated in epigastric area on exam

Front 54

What are the characteristic labs in a patient with pyloric stenosis?

Back 54

- Hypochloremia
- Hypokalemia
- Alkalosis

More recent onset of symptoms may show normal electrolytes

Front 55

How do you confirm a diagnosis of Pyloric Stenosis?

Back 55

- Imaging showing an enlarged pyloris - ultrasound has high sensitivity and specificity fore detecting pyloric stenosis by an experienced ultrasonographer

Front 56

What is the most important thing to do prior to proceeding to surgical repair of pyloric stenosis?
A. Feed the infant more because he has not been taking enough calories and is at risk for malnutrition.
B. Further confirm the diagnosis with a upper GI contrast study.
C. Nothing—go straight to the operating room for repair in order to prevent further issues.
D. Rehydrate and correct electrolyte abnormalities.

Back 56

Rehydrate and correct electrolyte abnormalities.

Front 57

How should you treat a patient with pyloric stenosis?

Back 57

- Surgical intervention is the definitive management (pyloromyotomy done laparoscopically)
- Must rehydrate and correct electrolyte abnormalities prior to surgery
- Post-op management includes feeding within several hours of surgery

Front 58

Why must you rehydrate and correct electrolyte abnormalities prior to surgery for pyloric stenosis?

Back 58

Alkalosis at the time of surgery carries an increased risk for post-operative apnea

Front 59

How do you rehdyrate a patient with pyloric stenosis before taking them to surgery?

Back 59

Normal saline bolus followed by dextrose containing fluids (D5) and isotonic saline (1/2 normal saline) with KCl added to correct the metabolic alkalosis

Front 60

What electrolyte abnormality does pyloric stenosis lead to?

Back 60

- Hypokalemia
- Hypochloremic
- Metabolic alkalosis

Front 61

When should you consider a diagnosis of pyloric stenosis?

Back 61

In a neonate with projectile non-bilious emesis, hunger after vomiting, and poor weight gain