6 Fluids and Electrolytes, part 2 Flashcards
Hypokalemia most commonly occurs secondary to
profuse vomiting and/or diarrhea
IV replacement of potassium
If IV therapy is necessary, potassium 0.2 to 0.3 mEq/kg/h is generally adequate
In extremely urgent situations, such as hypokalemia-induced respiratory insufficiency or cardiac manifestations, potassium 0.5 mEq/kg/hour can be adminsitered (maximum 20 mEq/dose), with continuous ECG monitoring
If potassium chloride infusion conentration exceeds 60 mEqs/L, the infusion will need to run through a central line, because potassium is a vein irritant
Potassium levels in DKA
In diabeteic ketoacidosis profound hypokalemia can result from osmotic diuresis, although in the face of the hydrogen-potassium shift that accompanies acidemia, serum levels may be normal or falsely elevated
In DKA, potassium repletion should begin early in the course of therapy, because diuresis-induced depletion can result in profound hypokalemia as acidosis is corrected and serum potassium shifts into cells.
Most common manifestation of hyperkalemia
Cardiac conduction delay is the most common manifestation of hyperkalemia and is potentially life threatening
- Peaked T waves are the first manifestation
- followed by prolonged PR interval
- and then widening of the QRS complex, an ominous finding that can precede the
- characteristic “sine wave” pattern, leading to
- ventricular dysrhythmias and asystole
Dosing of 10% calcium gluconate
100 mg/kg (1mL/kg/dose) IV at a rate not to exceed 100 mg/min
10% means 100mg/mL
maximum of 3 grams per dose
may be repeated in 5 mins if necessary
remarks on calcium chloride
max 1 gram per dose
must be given via central line or IO due to vein sclerosis
may be repeated in 5 mins if necessary
sodium bicarbonate in hyperkalemia
if acidotic (pH <7.3), 1-2 mEq/kg IV
typical adult dose 50-100 mEq
may be repeated every 5-10 mins as needed
In patients with hyperkalemia secondary to metabolic acidosis, normalization of serum pH usually restores serum potassium to normal levels.
Definition of hypocalcemia
< 8 mg/dL
<2 mmol/L
ionized Ca <4.4 mg/dL
ionized Ca <1.1 mmol/L
Another common cause of hypocalcemia is
hyperventilation:
the decreased partial pressure of carbon dioxide results in an acute respiratory alkalosis that rapidly decreases levels of ionized calcium
The most characteristic ECG abnormality in hypocalcemia is
a prolonged QT interval.
If a neonate is seen with hypocalcemia, a ____________ should be done to look for a thymic shadow in infants and young children.
chest radiograph
Treatment of hypocalcemia
calcium gluconate 10% in a dose fo 100 mg/kg at a rate not to exceed 100mg/min, with continuous ECG monitoring.
definition of hypercalcemia
> 11 mg/dL
Probably the most common cause of hypercalcemia in children is
malignancy involving the lymphoreticular system.
hypercalcemia can cause
constipation
Treatment of hypercalcemia
Treatment depends on the cause.
Acutely, patients with functioning kidneys can be treated with aggressive IV hydration (e.g., twice maintenance), with or without furosemide, 1 to 2 mg/kg IV, to a maximum of 40 mg. Then, treat the underlying cause.
Clinical manifestations of hypomagnesemia
Clinical manifestations are similar to those seen with hypocalcemia:
* muscle spasms, weakness, or even atrophy may occur
* CNS symptoms include ataxia, abnormal movements, nystagmus, and seizures
* cardiac changes include prolonged pR and QT intervals and may predispose to arrhythmias such as torsades de pointes
treatment of hypomagnesemia
In symptomatic patietns (e.g., those with seizures, arrhytmias), give IV magnesium sulfate, 25 to 50 mg/kg administered as a 10% solution over 30 minutes, and repeat every 4 to 6 horus as needed
most common cause of hypermagnesemia
The most common cause is ingestion of exogenous magnesium, typically found in antacids and laxatives.
* Patients with renal dysfunction are at increased risk
clinical manifestations of hypermagnesemia
Clinical manifestations include hypotension, loss of deep tendon reflexes, and respiratory failure
Cardiac manifestsions include widening of the QRS, PR, and QT intervals
treatment of hypermagnesemia
Treatment is removal of exogenous sources and hydration accompanied by diuresis.
Severe symptoms may be mitigated with IV calcium, 0.5 mL/kg delivered as calcium gluconate.
* dialysis is effective in patients with renal failure
