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NCLEX-RN · Physiological Integrity

NCLEX-RN: Physiological Adaptation Concepts

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Overview

This chapter covers clients whose bodies are failing to keep balance, such as those with fluid and electrolyte problems, shock, breathing or heart emergencies, and brain injuries. The exam asks you to spot changes early and act in the right order.

High potassium can cause tall, peaked T waves and dangerous rhythms, while low potassium causes muscle weakness and flat T waves. Too much fluid shows as crackles, swelling and weight gain; too little shows as a fast pulse, dry mouth and low urine output. In shock, an early sign is a rising heart rate and restlessness, and low blood pressure often comes later. In sepsis, draw blood cultures before starting antibiotics, and do not delay either.

For heart rhythms, ventricular fibrillation needs CPR and defibrillation, while asystole needs CPR and medicine but no shock. In normal sinus rhythm, a P wave comes before every evenly spaced QRS, while atrial fibrillation is irregular and raises stroke risk. Rising pressure in the skull often first shows as a change in level of consciousness. If a chest tube comes out of the chest, cover the site with a sterile dressing taped on three sides. Know how DKA and HHS differ.

Key concepts

  • High and low potassium

    High potassium, often from kidney failure, can cause muscle weakness, tall peaked T waves and life-threatening rhythms. Low potassium, often from diuretics or vomiting, causes muscle weakness, cramps, flat T waves, U waves and rhythm problems.

    Memory tipPeaked T waves = potassium too high. Low potassium also raises the risk of digoxin toxicity.

  • Fluid volume excess and deficit

    Too much fluid causes crackles in the lungs, swelling, bounding pulse and weight gain. Too little causes a fast weak pulse, dry mouth, low urine output and dizziness on standing.

    Memory tipDaily weight, at the same time with the same scale, is the best way to track fluid.

  • Early signs of shock

    Shock means organs are not getting enough blood. Early signs include a rising heart rate, restlessness and cool, pale skin. Blood pressure often falls later.

    Memory tipDo not wait for low blood pressure; a rising pulse and new anxiety are early clues.

  • Sepsis care

    Sepsis is a life-threatening body response to infection. Care includes blood cultures, then broad antibiotics without delay, IV fluids and close watching of blood pressure and urine output.

    Memory tipCultures first, then antibiotics, but do not hold antibiotics for long to get cultures.

  • Atrial fibrillation

    In normal sinus rhythm, a P wave comes before every evenly spaced QRS. In atrial fibrillation, there are no clear P waves, the baseline is wavy and the QRS complexes are unevenly spaced. Blood can pool in the heart and form clots, which raises stroke risk.

    Memory tipIrregular rhythm with no clear P waves: think atrial fibrillation and ask about blood thinners.

  • Shockable and non-shockable rhythms

    Ventricular fibrillation (chaotic waves, no QRS) and pulseless ventricular tachycardia are treated with CPR and defibrillation. Asystole (a nearly flat line) and pulseless electrical activity are treated with CPR and epinephrine, not shocks.

    Memory tipNo electrical activity, nothing to shock: asystole gets CPR, not a shock.

    Source: American Heart Association (Guidelines for CPR and ECC) · as of 2025

  • Increased intracranial pressure

    Rising pressure inside the skull. The earliest sign is often a change in level of consciousness. Later signs include a rising systolic blood pressure with a slow pulse and irregular breathing (Cushing's triad).

    Memory tipKeep the head of the bed raised and the head in line with the body; avoid things that raise pressure, such as straining.

See it in a picture

Four Lead II rhythm strips stacked on ECG grid paper: normal sinus rhythm with a P wave before every evenly spaced QRS; atrial fibrillation with unevenly spaced QRS and a wavy baseline; ventricular fibrillation with chaotic waves and no QRS; asystole as a nearly flat line.
Normal sinus rhythm, atrial fibrillation, ventricular fibrillation (shockable) and asystole (not shockable)

Often tested

  • Match ECG changes to potassium: peaked T waves high, flat T and U waves low.
  • Daily weight is the best measure of fluid change.
  • A rising heart rate and restlessness are early shock signs; low blood pressure often comes later.
  • On a strip: normal sinus rhythm has a P wave before each even QRS; atrial fibrillation is irregular; shock ventricular fibrillation, not asystole.
  • A change in level of consciousness is often the first sign of rising pressure in the skull.
  • If a chest tube falls out, cover the site with a sterile dressing taped on three sides.

Easy to confuse: DKA and HHS

PointDKAHHS
Usual diabetes typeType 1Type 2
Ketones and acidosisPresentLittle or none
Blood glucoseHighOften extremely high
Key signsFruity breath, deep fast breathingSevere dehydration, confusion
Main treatmentIV fluids, insulin, potassium watchIV fluids, insulin, potassium watch

3 sample questions

Verified practice questions from this unit.

Practice questionReviewedPhysiological Integrity › Physiological Adaptation★★★★★

Question 1. A client with type 1 diabetes reports feeling shaky and sweaty. The fingerstick glucose is 58 mg/dL. The client is awake and able to swallow. What should the nurse do first?

  1. ① Give glucagon by injection
  2. ② Give 50% dextrose by IV push
  3. ③ Give 15 grams of a fast-acting carbohydrate, such as 4 ounces of fruit juice
  4. ④ Recheck the glucose in 1 hour
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Answer: ③ Give 15 grams of a fast-acting carbohydrate, such as 4 ounces of fruit juice

Key point: Awake hypoglycemic client: 15 g fast carbs, recheck in 15 min

A glucose below 70 mg/dL is hypoglycemia (low blood sugar). For a client who is awake and can swallow, the first step is the "15-15 rule":

  1. Give about 15 grams of fast-acting carbohydrate (for example, 4 ounces of juice or regular soda, or glucose tablets).
  2. Recheck the glucose in 15 minutes.
  3. Repeat if it is still low. Once it is normal, give a snack or meal if the next meal is not soon.

Wrong choices

  • "50% dextrose IV": used when the client cannot swallow safely or is unconscious and has IV access.
  • "Glucagon injection": used when the client cannot swallow and there is no IV access.
  • "Recheck in 1 hour": waiting without treatment lets the sugar drop further and can lead to seizures or loss of consciousness.
Practice questionReviewedPhysiological Integrity › Physiological Adaptation★★★★★

Question 2. A client is brought to the emergency department with sudden weakness of the left arm and a drooping face. Which information is most important for the nurse to obtain right away?

  1. ① The time the client was last known to be normal
  2. ② The date of the client's last flu vaccine
  3. ③ The client's usual diet
  4. ④ Whether any family members have had a stroke
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Answer: ① The time the client was last known to be normal

Key point: Stroke: find out when the client was last known well

Sudden one-sided weakness and facial droop are signs of a stroke. For an ischemic stroke (caused by a clot), clot-dissolving medicine and clot-removal procedures can only be used within certain time windows. Treatment decisions start from the time the client was last known to be normal ("last known well"). If the client woke up with symptoms, the last known well time is when they went to sleep.

The nurse also checks the blood glucose quickly, since low blood sugar can look like a stroke.

Wrong choices

  • "Usual diet": useful later, but it does not guide emergency treatment.
  • "Family history of stroke": a risk factor, but it does not change what is done right now.
  • "Last flu vaccine": not related to emergency stroke care.
Practice questionReviewedPhysiological Integrity › Physiological Adaptation★★★★★

Question 3. Which finding most directly points to left-sided heart failure?

  1. ① Fluid in the abdomen (ascites)
  2. ② Swelling of the ankles
  3. ③ Crackles in the lungs with shortness of breath
  4. ④ An enlarged liver
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Answer: ③ Crackles in the lungs with shortness of breath

Key point: Left-sided failure backs up into the lungs; right-sided into the body

Think of where the blood backs up.

  • The left side of the heart receives blood from the lungs. When it fails, blood backs up into the lungs: crackles, shortness of breath, cough, and trouble breathing when lying flat.
  • The right side receives blood from the body. When it fails, blood backs up into the body: ankle swelling, enlarged liver, fluid in the abdomen, and swollen neck veins.

Many clients have both, but crackles are the sign most directly linked to the left side.

Wrong choices

  • "Swelling of the ankles": a sign of right-sided failure.
  • "Enlarged liver": a sign of right-sided failure.
  • "Ascites": a sign of right-sided failure.
Practice 5 questions from this unit →