Potassium

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Joel M. Topf, MDNephrology Attending

Potassium

Emergencies

• Decreased intake of potassium Alcoholics Anorexia

• Transcellular shift of potassium ß-agonists Dobutamine

• Renal potassium excretion Diuretics Decreased chloride delivery Hyperaldosteronism

Etiologies of hypokalemia

EKG findings with hypokalemia• hypokalemia produces

EKG changes which are not necessarily related to the K+ level Flattening of T waves Increased prominence of

U waves (look at V4, 5, 6) ST depression Increased prominence of

P waves Inversion of T waves

• 81-year-old woman develops chest pain during treatment of an asthma exacerbation.

• The patient was found to be: Disoriented Complaining of stabbing,

non-radiating chest pain Nausea, vomiting,

dyspnea Severe muscle weakness

• Potassium of 0.9 mEq/L. • History of taking herbal

remedies, including natural licorice. Licorice contains

glycyrrhizic acid

Hypokalemia and Arrhythmias• Norwegians with AMI• N= 1035

23 K ≤ 3.0 94 K = 3.1-3.5 357 K = 3.6-4.0 393 K = 4.1-4.5 141 K = 4.6=5.1 24 K ≥ 5.2

• Results are the incidence of arrhythmias by K level

0

10

20

30

40

50

≤3.0 3.1-3.5 3.6-4.0 4.1-4.5 4.6-5.1 ≥5.2

VF, VFl, VT, AF VT, VF VF

Nordrehaug, JE, Acta Med Scand, Sup. 1981 647, 101-107

Treatment of hypokalemia

• Give potassium Oral is preferred route

20-40 mEq qd-q6h

KCl is superior to Kphos or K-acetate

IV for patients who are NPO or have dangerously low potassium

• Liberal use of K sparing diuretics

• Check and correct Mg deficiency



How much K to give

• Altered cellular distribution No total body K deficit so

any K given will need to be excreted after the maldistrib-ution is rectified

• A compilation of 7 separate metabolic balance studies reveals the following graph

2

3

4

5

0 100 200 300 400 500 600 700 800

K Deficit (mmol/70 kg body Wt)

Serum K (mmol/L)

Serum K Replacement

3.0 100

2.0 200

1.0 400

Check the Creatinine first

Problems with IV potassium

Concentrated IV potassium solutions cause phlebitis

Dilute IV potassium in saline causes volume overload

IV potassium in dextrose cause a release of insulin

lowering plasma potassium

Hyperkalemia

0

0.05

0.1

0.15

0.2

0.25

Control Infusion

QRS duration T-Wave Amplitude

Treatment of hypokalemia: IV KCl• N = 40 ICU patients

with arterial lines and hypokalemia. Patients given 20

mmol of KCl in 100 mL

Pre-infusion K = 2.9 26 central vein 14 peripheral Continuous EKG

monitoring in 31 and pre and post 12 lead EKG in all 40.

0.0

0.1

0.2

0.3

0.4

0.5

0 15 30 45 60 75 90 105 120

Time (min)

∆ K (mmol/L)

0

2

4

6

8

10

12

14

16

18

20

Control Infusion

PAC PVC

Kruse, JA, Et al J Clin Pharm. 1994 34, 1077-1082

Hyperkalemia• Plasma potassium

over 5.5 mEq/L• Primary problems

are weakness and arrhythmias Bradycardia Ventricular fibrillation

• Increased intake of potassium Enteral Parenteral

Etiologies of hyperkalemia

• Transcellular shift of potassium Lack of insulin Beta-blockers Cardiac glycosides Tissue destruction

• Renal potassium excretion Renal failure Decreased distal delivery of Na Hypoaldosteronism

Hyperkalemia: Clinical Sequelae• Arrhythmia• Paralysis

Due to abnormal nerve conduction

Ascending paralysis mimicking GBS documented with K of 7

In review of all reported cases of hyperkalemic paralysis:

Ave. K = 9Half were on a K

sparing diuretic

Evers, S. Et al. Secondary hyperkalaemic paralysis. J Neurol Neurosurg Psychiatry 64, 249-252 (1998).

EKG findings with hyperkalemia

• Short QT interval

• Peaked T waves

• Widened QRS complex

• The EKG changes into a sinusoidal pattern

EKG Changes with hyperkalemia

Treatment of hyperkalemia: Calcium• If EKG signs are present

give calcium• Calcium Chloride is

more effective than calcium gluconate

• Onset of action is instant and duration approx. 1 hour

• May repeat until EKG normalizes

• Avoid if patient has digoxin toxicity

In animal studies, verapamil ablates the cardioprotective effect of calcium.

Bisogno, J. L., Langley, A. & Von, D. M. M. Critical Care Medicine. 22, 697-704 (1994).

Nugent, M., Tinker, J. H. & Moyer, T. P. Anesthesiology 60, 435-439 (1984).

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Ca Content (mmol/mL)

Ca Gluconate Ca Cl

• Stop intake of potassium Enteral Parenteral

• Induce a transcellular shift of potassium Insulin Albuterol

• Enhance potassium excretion Renal Colonic

Treatment of hyperkalemia:

Treatment of hyperkalemia: Speed

• N=10, no diabetics• Hemodialysis

patients, K = 5.5.• 5 protocols:

1. Bicarbonate 8.4%.2. Bicarbonate 1.4%.3. Epinephrine

0.05µg/kg/min4. Insulin 5mU/kg/min +

Glucose 5mg/kg/min5. Hemodialysis w/ 1 K bath

-1.5

-1.3

-1.1

-0.9

-0.7

-0.5

-0.3

-0.1

0.1

0.3

0 10 20 30 40 50 60

Time (min)

Change in K

NaHCO3 8.4% NaHCO3 1.4%

Epinephrine Insulin Glucose

Dialysis

Blumberg Et al. Amer J Med; 1988: 85, 507-512.

Bicarbonate for hyperkalemia: duration

• N=12• Hemodialysis patients,

K ≥ 5.8.• Given sodium

bicarbonate 4 mmol/min for 1 hour 0.5 mmol/min for 5 hours

• Total 390 mmol 8 amps of bicarbonate and

a liter of fluid for a decrease in K of 0.5 mmol/L

-1.5

-1.3

-1.1

-0.9

-0.7

-0.5

-0.3

-0.1

0.1

0.3

0 60 120 180 240 300 360

Time (min)

Change in K

p>0.05 P<0.05

Blumberg Et al. Kidney International; 1992: 41, 369-374.

At 1 hour the small drop in K was fully accounted for by dilution.

At 6 hours 50±7% of the fall in K was due to ECF expansion

Albuterol for hyperkalemia• N=10• Hemodialysis patients

with pre-dialysis K > 5• Given Nebulized:

Saline. K=5.74 10mg albuterol. K=5.93 20 mg albuterol. K=5.81 on separate days.

• Patients served as their own controls.

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0 30 60 90 120

Time (min)

Change in K

Saline 10 mg 20 mg

Allon Et al. Annals of Int Med; 1989: 110, 426-429.

Albuterol for hyperkalemia: Synergy?• N=12• Hemodialysis patients

with pre-dialysis K > 5• No diabetics or ß-

blockers• Given:

10 u IV insulin + D50 20 mg nebulized

albuterol. Combination of both Patients served as their

own controls.

-1.5

-1.2

-0.9

-0.6

-0.3

0.00 15 30 45 60

Time (min)

Change in K

Insulin Albuterol Combination

Allon Et al. Kidney International; 1990: 38, 869-872.


• Move potassium into the cells Insulin and Glucose

Glucose 0.5-1 Amp

Insulin 10 unit IV

Albuterol10-20 mg

nebulized

Do not use sodium bicarbonate Cooper, DJ et al, Annals Int Med 1990;112:492-8.


• Move potassium into the cells Insulin and Glucose

Glucose 0.5-1 Amp

Insulin 10 unit IV

Albuterol10-20 mg

nebulized

Do not use sodium bicarbonate

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

Before After

Ionized Calcium (mmol/L)

Bicarbonate Saline

Cooper, DJ et al, Annals Int Med 1990;112:492-8.

Treatment of hyperkalemia:• Increase the

excretion of potassium Furosemide (Lasix)

Only in patients with working kidneys

20 x sCr IV push Sodium polystyrene

resins (Kayexalate) in patients whose kidneys don’t work

30 g Dialysis

• Make sure the glucose is normal

• Rule out urinary obstruction

Life after death

• 70-year-old man who developed cardiac arrest secondary to hyperkalemia (K=8.5) from chronic renal failure from obstructive uropathy.

• The patient experienced electromechanical dissociation and approximately 26 minutes of asystole after which the resuscitation was suspended

• 8 to 10 minutes after declaration of death, as the emergency department personnel were preparing to transport him to the morgue, the patient was noted to have spontaneous respiration.

• The patient survived and was discharged without apparent neurologic sequelae.

Quick, G Et al. Annals of Emergency Med; 1994: 24, 305-311.

Potassium

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