Pearls of Knowledge: WBC and the Differential

Lab Values: WBC and the Differential 

Pearls of Knowledge          ©

There are many conditions that will alter the white blood cell count. The most common cause of an elevation is a bacterial or parasitic infection or any type of an inflammatory disorder. Some of the immune system and thyroid disorders may be implicated. Select drugs, such as glucocorticoids will also elevate the count. Leukemia will elevate the count; however, the cells are dysfunctional, and a risk for infection is present.

A low white blood cell count is often caused by viral infections, severe infections due to depletion of the cells, congenital disorders, damage to the bone marrow, autoimmune disorders, and medications such as anti-infectives or chemotherapy that suppress the bone marrow. Leukopenia is white blood cells < 1,000 cells/mm3. Agranulocytosis is a severe decrease of < 200 cells/mm3.

Types of white blood cells 


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Pearls of Knowledge: Torsades de pointes

Dysrhythmias: Torsades de Pointes

Pearls of Knowledge          ©

Torsades de pointes is a life-threatening type of ventricular tachycardia that is associated with a prolonged QT interval. The QT interval is comprised of the absolute (ARP) and relative refractory (RRP) periods. During the absolute refractory period, no stimulus can cause an electrical response in the heart. During the relative refractory period, a strong stimulus can trigger a response, such as Torsades de pointes.

The prolongation of the QT interval may be due to a congenital defect but is most frequently caused by drug therapy (of which, there are many). A prolonged QT interval is also seen in electrolyte imbalances, particularly hypokalemia and hypomagnesemia. Treatment for Torsades de pointes is the administration of magnesium, even in the presence of a normal magnesium level. If pulseless, then defibrillation.

Measuring the QT Interval

The QT...

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Pearls of Knowledge: Four Heart Sounds

Heart Sounds: Recognizing the “Four” Which are Possible

Pearls of Knowledge          ©

In listening to the heart, a systematic approach is important. And remember, the more you listen, the better your skills will become. In acute conditions, listening to heart sounds is very important on presentation, and then with subsequent assessments. If heart sounds change, it generally signifies a deterioration in condition.

 Be sure to determine the following with assessment.

  • The strength of the heart sounds.
  • The heart sounds heard (S1, S2, S3, S4).
  • If systolic or diastolic murmurs are present.
  • If a friction rub is present.

Listening to the four possible heart sounds

As the valves close, S1 and S2 are produced. 

  • S1 indicates closure of the mitral and tricuspid valves, is heard the loudest in those areas of the heart and occurs during systole. 
  • S2 indicates closure of the aortic and pulmonic...
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Anion Gap

We often see anion gap reported on patient charts. The gap defines the type and cause of acidosis. Normal is 8-16 mEq/L. The formula is Na+ + K+ - (Cl- + HCO3-) and luckily the computer generates the reading for us!

Only in select clinical situations, does the reading have significance from a nursing perspective. We will discuss two of the most common in this “Pearls of Knowledge”, utilizing our Memory Hint.

#1 When to give sodium bicarbonate based on the anion gap.

#2 The implication the anion gap has in a patient in diabetic ketoacidosis and insulin administration.

Anion gap and sodium bicarbonate

When a patient presents in metabolic acidosis, nurses are anticipating the administration of sodium bicarbonate. However, this may or may not be appropriate. When the anion gap is normal, sodium bicarbonate is the appropriate treatment. When the anion gap is high, the underlying condition needs to be treated, such as insulin administration in diabetic ketoacidosis.

Look at...

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Breath Sounds

You are invited to check out a quick review of Breath Sounds to incorporate in the assessments you make as a professional.


  • Heard on inspiration and indicate fluid, atelectasis, or pneumonia
  • In left sided heart failure and pulmonary edema, crackles will be persistent
  • When heard in post-operative conditions and pulmonary or fat emboli, they are most often due to atelectasis and will clear with cough and deep breathing exercises
  • Will be heard in bacterial pneumonia, along with bronchial (loud) breath sounds, but are often absent in viral pneumonia


  • Primarily heard on expiration and indicates movement of air through mucus
  • Will be heard when the patient needs to be suctioned and should clear when suctioning is successful


  • Indicates air movement through narrowed airways or a blockage in the vocal cords
  • Expiratory wheezing indicates a mild obstruction
  • Inspiratory wheezing is heard in chronic asthma
  • Inspiratory and expiratory wheezing is heard in acute asthma...
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ABG Analysis

Check out the simplest ABG interpretation ever!

There is a lot of information available about ABG analysis. It is all important, but as a nurse at the bedside, you may be looking for a “quick and dirty” way to get to the interpretation. As I have presented this method in numerous seminars throughout the years, I frequently hear…”where have you been all my career? I have always struggled with interpretation…and this makes sense!”

Your memory hint for ABG interpretation is “If the pH and Bicarbonate are Both in the same direction, it is a metabolic disturbance”. This is similar to “R-O-M-E” which you may have learned in nursing school. But, as a practicing nurse, you may have learned it a long time ago.

As you click on the image below, check out the three examples using this method. Note the way the arrows are going with the pH and HCO3 to lead you to the correct interpretation. Patient example #3 is a septic patient....

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