week 9 other ECG findings

35 Questions

What is the normal serum potassium level?

3.5-5.0 mmol/L

What is the primary route of potassium excretion?

Through the kidneys

What condition is characterized by a serum potassium level greater than 5.1 mmol/L?

Hyperkalemia

Which of the following can reduce potassium excretion?

Adrenal insufficiency

What is a potential consequence of tissue trauma?

Hyperkalemia

What is the typical electrocardiogram (ECG) finding in a patient with hyperkalemia, when the potassium level is around 5.5 mmol/L?

Tall, narrow peaked T waves

What is the effect of hyperkalemia on myocardial electrical activity?

Depresses myocardial electrical activity, leading to bradycardia, widening of the QRS complex, and ultimately, arrhythmias

At what potassium level (in mmol/L) does the QRS complex widen and ST depression occur?

6.0 mmol/L

What happens to the PR interval and P wave at a potassium level of 6.5 mmol/L?

PR interval prolongs and P wave flattens

What happens to the P waves at a potassium level of 7.0 mmol/L?

P waves begin to disappear

What is the terminal arrhythmia associated with hyperkalemia?

Sine wave

What is the serum potassium level defining hypokalemia?

< 3.5 mmol/L

What are some causes of hypokalemia?

Decreased intake, increased gastrointestinal or renal loss, and transcellular shifts

What is the normal range of calcium levels in the blood?

Ca > 8.5 mg/L

What can cause hypocalcemia?

Chronic renal disease, acute pancreatitis, hypoparathyroidism

What is the effect of decreased extracellular calcium on the heart?

Decreased myocardial contractility and altered action potential duration

What are the ECG changes seen in hypocalcemia?

Bradycardia, prolonged QTc interval, and flattened or inverted T waves

What are the treatment options for hypocalcemia?

Calcium gluconate, calcium chloride

What is the effect of calcitonin on calcium levels?

Decreased calcium levels

What is the effect of diuresis on calcium levels?

Increased calcium excretion

What is the effect of hypocalcemia on the inflammatory response?

Increased inflammatory response in the pericardium

What is the primary treatment for hypercalcemia aside from addressing the underlying cause?

Potassium replacement

In addition to potassium replacement, what other electrolyte may need to be considered for replacement in hypercalcemic patients?

Magnesium

At what level of calcium does hypercalcemia become a concern?

Ca > 10.5 mg/dL

What is one of the underlying conditions that can contribute to hypercalcemia?

Renal disease

How does hypercalcemia affect the QTc interval on an ECG?

Shortened QTc interval

What ECG changes are commonly associated with hypercalcemia?

Bradycardia, widened QRS complex, shortened ST segment, and depressed T waves

What ECG changes are associated with pericarditis?

PR depression, diffuse ST elevation, scooping of the ST segments, and notching of the end of the QRS complex

What is the cause of ECG changes associated with CNS injury?

Excessive sympathetic tone and catecholamine production

What ECG changes are associated with hypothermia?

Tremor artifact, atrial fibrillation with slow ventricular rate, J waves (Osborne waves), bradycardia, and prolongation of the PR, QRS, and QT intervals

What is the core temperature at which hypothermia can cause ECG changes?

Less than 35°C

What is the typical ECG finding in CNS injury?

ST depression, T wave inversion, and prolonged QT interval

What is the significance of PR depression in ECG?

It is an indicator of pericarditis

What is the effect of excessive sympathetic tone on the ECG in CNS injury?

It causes ST depression, T wave inversion, and prolonged QT interval

What is the significance of J waves in ECG?

They are an indicator of hypothermia

Study Notes

Potassium Regulation

98% of potassium is located intracellularly, with 2% in the extracellular fluid
Normal serum potassium level is 3.5-5.0 mmol/L
Potassium is mainly excreted through the kidneys, and its excretion can be reduced by factors like adrenal insufficiency

Hyperkalemia (Serum K+ > 5.1 mmol/L)

Causes: renal failure, adrenal insufficiency, medications affecting the renin-angiotensin-aldosterone pathway, metabolic acidosis, and tissue trauma
ECG changes:
- 5.5 mmol/L: Tall, narrow peaked T waves
- 6.0 mmol/L: QRS widens and ST depression
- 6.5 mmol/L: PR interval prolongs and P wave flattens
- 7.0 mmol/L: P waves begin to disappear, sine wave is terminal

Hypokalemia (Serum K+ < 3.5 mmol/L)

Causes: decreased intake, increased gastrointestinal or renal loss, and transcellular shifts
Treatment: Potassium replacement, consider replacing Magnesium

Calcium Regulation

Ca > 10.5 mg/dL: Hypercalcemia
Causes: renal disease, hyperparathyroidism, cancer
Effects: depresses depolarization and neuromuscular activity, leading to shortened QTc interval
ECG changes: bradycardia, widened QRS complex, shortened ST segment, and depressed T waves
Treatment: Diuresis, Calcitonin
Ca < 8.5 mg/L: Hypocalcemia
Causes: chronic renal disease, acute pancreatitis, hypoparathyroidism
Effects: decreased myocardial contractility and altered action potential duration, affecting the QTc interval
ECG changes: bradycardia, prolonged QTc interval, and flattened or inverted T waves
Treatment: CALCIUM GLUCONATE, CALCIUM CHLORIDE

Miscellaneous ECG Changes

Pericarditis: PR depression, diffuse ST elevation, scooping of the ST segments, and notching of the end of the QRS complex
CNS Injury: ST depression, T wave inversion, and prolonged QT interval
Hypothermia: tremor artifact, atrial fibrillation with slow ventricular rate, J waves (Osborne waves), bradycardia, and prolongation of the PR, QRS, and QT intervals

This quiz covers the physiology of potassium in the human body, including its location, normal serum levels, and excretion. Test your knowledge of potassium's biological functions and regulation.

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