Read the pH: below 7.35 is acidosis, above 7.45 alkalosis.
Find the value that explains it: PaCO₂ moving opposite to the pH is respiratory, HCO₃⁻ moving with the pH is metabolic.
Look at the other value: normal means uncompensated, abnormal in the compensating direction means partial compensation, and a normal pH with both abnormal means full compensation.
In a metabolic acidosis, compare PaCO₂ with Winter’s formula, 1.5·HCO₃⁻ + 8 ± 2, and calculate the anion gap Na⁺ − (Cl⁻ + HCO₃⁻).
Check a high anion gap with the delta ratio and, when albumin is low, with the corrected gap.
Write down what is asked: a pump rate, a volume, kilocalories, grams of protein or water.
Turn energy into volume with mL = kcal/(kcal/mL), and volume into protein with litres × g/L.
Divide by the hours the feed actually runs for a rate, or by the number of feeds for a bolus.
For needs, multiply kcal/kg or g/kg by the weight the rule names; find the ideal body weight with Devine: 50 or 45.5 + 2.3 × (inches − 60).
For PN, find grams as % × mL/100, then use 3.4 kcal/g for dextrose, 4 kcal/g for amino acids and the stated kcal/mL for lipid.
ECG rhythm strip interpretation
Paper (25 mm/s, 10 mm/mV)
1 small box = 0.04 s, 1 large box = 0.20 s, 10 mm = 1 mV
Heart rate, regular rhythm
300 ÷ large boxes = 1500 ÷ small boxes = 60 ÷ RR (s)
Heart rate, irregular rhythm
QRS complexes in 6 s × 10
Normal PR interval
0.12–0.20 s
Normal QRS duration
< 0.12 s
QTc (Bazett)
QT/√RR
QTc (Fridericia)
QT/∛RR
QTc (Framingham)
QT + 154·(1 − RR)
Sinus rates
bradycardia < 60, normal 60–100, tachycardia > 100 /min
Escape rates
junctional 40–60, ventricular 20–40 /min
Fast rhythms
SVT 150–250 /min (narrow), VT > 100 /min (wide)
Method
Rate: for a regular rhythm divide 300 by the large boxes or 1500 by the small boxes between two R waves; for an irregular rhythm count the QRS complexes in 6 seconds and multiply by 10.
Rhythm: compare the R–R intervals. Equal is regular; a repeating pattern is regularly irregular; no pattern at all is irregularly irregular.
P waves: is there an upright P wave in lead II before every QRS, all alike? Look for fibrillatory or sawtooth waves, inverted P waves and P waves without a QRS.
PR interval: from the start of P to the start of the QRS, normally 0.12–0.20 s and constant. Watch whether it lengthens, stays fixed before a dropped beat, or varies at random.
QRS duration: below 0.12 s is narrow; 0.12 s or more is wide. Then name the rhythm, and for the QT use QTc = QT/√RR (Bazett) with times in seconds.
Prioritization & delegation
Method
Ask what will harm the patient soonest if nothing is done.
Apply ABC (C-A-B in cardiac arrest), then Maslow: physiological needs before safety, safety before psychological needs.
Compare the options: acute before chronic, unstable before stable, unexpected before expected, systemic before local, and check each finding against the patient’s baseline.
Assess before you act unless it is an emergency; then choose the step the others depend on.
For delegation, check the five rights: task, circumstance, person, directions and supervision. Assessment, teaching and evaluation stay with the RN.
Infection control & patient safety
Method
Start with standard precautions for every patient: hand hygiene, PPE for the expected exposure, safe sharps.
Keep sterile items sterile: if in doubt, it is not sterile; replace, never wipe.
Prevent harm in the environment: fall measures, restraints only as a last resort, RACE and PASS for fire.
Check the rights of medication administration, two identifiers and extra safeguards for high-alert drugs; report errors and near misses.
Lab values & electrolytes
Method
Compare the value with the laboratory’s own reference range, then with the patient’s baseline and trend.
Check the sample: hemolysis, a delay, or blood drawn near an IV can give false results.
Link the value to its typical signs and to the drugs and conditions that cause it.
Look for interactions: low potassium or magnesium increases digoxin toxicity; dehydration raises lithium.
Act on the patient: assess, hold a drug if the level is unsafe, read back critical values and inform the prescriber.
2Practice problems
1.Nursing fundamentalsMedium
A dying patient asks to see a chaplain or religious leader. What should the nurse do?
ATell the patient to wait until visiting hours tomorrow
BAsk the patient's doctor if a visit is allowed
CArrange the visit as soon as possible
DExplain that religious matters are not part of care
2.Nursing fundamentalsHard
Why is the level of sedation a useful early warning in a patient on opioids?
ASedation shows that the pain has completely gone and the dose is right
BSedation means the opioid dose is too low
CIncreasing sedation usually comes before respiratory depression
DSedation only occurs after the breathing has stopped
3.Clinical nursingMedium
Which ECG change is typical of hypokalaemia?
ATall, peaked T waves
BFlattened T waves and prominent U waves
CST elevation in leads II, III and aVF
DA very short PR interval with a delta wave
4.Clinical nursingHard
Which statement about oxygen in a patient with suspected acute coronary syndrome is correct?
AOxygen replaces the need for an ECG
BOxygen must never be given in chest pain
CHigh-flow oxygen should always be given, whatever the SpO2
DOxygen is given if the SpO2 is below the target range
5.Arterial blood gas interpretationMedium
A practice arterial blood gas shows pH 7.49, PaCO₂ 26 mmHg (3.5 kPa) and HCO₃⁻ 19 mmol/L. The primary disorder is respiratory alkalosis. How far is it compensated? Click your answer.
pH 7.49PaCO₂ 26 mmHg (3.5 kPa)HCO₃⁻ 19 mmol/L
1uncompensated
2partially compensated
3fully compensated
6.Arterial blood gas interpretationHard
At sea level, a practice gas taken on 40% oxygen shows PaO₂ 63 mmHg (8.4 kPa) and PaCO₂ 46 mmHg (6.1 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.
Practice exercise (made-up values, not clinical guidance). A patient has a pulse of 133/min and a blood pressure of 82/53 mmHg. Find the shock index SI = HR/SBP. Round to two decimal places.
HR 133/minBP 82/53 mmHg
SI =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). An adult weighs 81 kg and is 183 cm tall. Calculate the BMI and click the WHO weight category.
Practice exercise (made-up values, not clinical guidance). A man is 174 cm tall and weighs 102 kg. Find the actual weight as a percentage of the ideal body weight, %IBW, using the Devine formula (1 in = 2.54 cm). Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1000 mL of parenteral nutrition with final concentrations of 15% dextrose and 4.25% amino acids, plus 100 mL of 20% lipid emulsion (2 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
1000 mLdextrose 15%amino acids 4.25%lipid 100 mL · 2 kcal/mL
E = kcal/day
11.ECG rhythm strip interpretationMedium
Measure the QT interval and the R–R interval on this regular lead II strip, then calculate the rate-corrected QTc with Bazett’s formula QTc = QT/√RR (both in seconds). Give the answer in seconds to three decimals.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
QTc = s
12.ECG rhythm strip interpretationHard
Interpret this lead II strip. Which interpretation can you defend from this single strip? Click your answer.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
1second-degree AV block type I (Wenckebach)
2first-degree AV block
32:1 AV block (type undetermined)
4third-degree (complete) AV block
13.Prioritization & delegationMedium
A patient is receiving opioids after surgery. Which finding usually comes before opioid-induced respiratory depression?
AIncreased appetite and thirst
BA sudden rise in pain scores
CA rise in blood pressure with flushed cheeks
DIncreasing sleepiness that is hard to rouse
14.Prioritization & delegationHard
A nurse teaches a patient to inject enoxaparin at home. Which statement shows a need for further teaching?
A“I will change the injection site each time.”
B“I will inject into the fat of my abdomen, away from the navel.”
C“I will tell my doctor if I notice unusual bruising or bleeding.”
D“I will rub the area after the injection to help it absorb.”
15.Infection control & patient safetyMedium
What should a nurse do after an accidental splash of a patient’s blood into the eyes?
ARub the eyes gently with a clean, dry tissue to remove the blood first
BApply antibiotic eye drops and tell no one
CFinish the procedure, then report it the next day
DRinse the eyes at once with plenty of water or saline, then report
16.Infection control & patient safetyHard
A patient was harmed by a medication error and asks the nurse what happened. Which approach is best?
ABe honest that an error occurred and involve the provider and team in disclosure per policy
BTell the patient nothing happened to avoid worry
CTell the patient to make a formal complaint to find out
DBlame the pharmacy for the error so that the nurse and the ward are not at fault
17.Lab values & electrolytesMedium
A healthy woman at 28 weeks of pregnancy has a mildly lower hemoglobin than before pregnancy, with a normal MCV and ferritin. What is the most likely explanation?
AIron is being lost through the kidneys during the pregnancy
BPregnancy hormones stop the bone marrow from making red cells
CThe fetus is destroying the mother's red cells in the circulation
DPlasma volume rises more than red cell mass, diluting the blood
18.Lab values & electrolytesHard
A patient's bedside glucose meter shows "HI" (above its measuring range). The patient is drowsy. What should the nurse do?
AGive oral glucose in case the reading is wrong and the patient is low
BRecord "HI" and repeat the meter test at the next scheduled time
CSend a venous sample to the lab and inform the provider at once
DAssume the meter is broken and give the usual insulin dose
3Solutions
1.Nursing fundamentals
Answer: C · Arrange the visit as soon as possible
Why this is the answer
Spiritual care is an important part of end-of-life care. The nurse responds promptly to such requests and records the patient's wishes.
Answer
C · Arrange the visit as soon as possible
2.Nursing fundamentals
Answer: C · Increasing sedation usually comes before respiratory depression
Why this is the answer
Patients usually become drowsy before their breathing slows dangerously. Checking sedation with a simple scale alongside respiratory rate allows early action.
Answer
C · Increasing sedation usually comes before respiratory depression
3.Clinical nursing
Answer: B · Flattened T waves and prominent U waves
Why this is the answer
Low potassium causes flattened or inverted T waves, ST depression and U waves. It increases the risk of arrhythmias, especially in patients on digoxin.
Answer
B · Flattened T waves and prominent U waves
4.Clinical nursing
Answer: D · Oxygen is given if the SpO2 is below the target range
Why this is the answer
Current guidance recommends oxygen in ACS only for hypoxaemia, as routine oxygen in patients with normal saturations has not been shown to help. Urgent ECG, analgesia and antiplatelet treatment remain priorities.
Answer
D · Oxygen is given if the SpO2 is below the target range
5.Arterial blood gas interpretation
Answer: partially compensated
Reading a blood gas (ROME): first the pH: below 7.35 is acidaemia, above 7.45 alkalaemia. Then find the value that explains it. PaCO₂ (normal 35–45 mmHg, 4.7–6.0 kPa) is the respiratory part and moves Opposite to the pH in a respiratory disorder; HCO₃⁻ (normal 22–26 mmol/L) is the metabolic part and moves in the same direction as the pH (Respiratory Opposite, Metabolic Equal). The other value shows the compensation: normal means uncompensated; abnormal in the direction that pulls the pH back while the pH is still abnormal means partially compensated; a normal pH with both values abnormal means fully compensated. Ranges differ slightly between laboratories; these are practice values.
ROME, value by value
pH 7.49: alkalaemia (above 7.45)
PaCO₂ 26 mmHg: low (35–45)
HCO₃⁻ 19 mmol/L: low (22–26)
Compensation
partially compensated
Answer
partially compensated
6.Arterial blood gas interpretation
Answer: A–a gradient = 164.7 mmHg
Derived values: calculated serum osmolality is 2·Na⁺ + glucose + urea with all values in mmol/L (2·Na⁺ + glucose/18 + BUN/2.8 with glucose and BUN in mg/dL); normal is about 275–295 mOsm/kg. The P/F ratio is PaO₂ divided by FiO₂ as a fraction. The alveolar oxygen pressure is PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 mmHg at sea level, and the A–a gradient is PAO₂ − PaO₂.
Blood pressure values: pulse pressure PP = SBP − DBP. Mean arterial pressure MAP ≈ (SBP + 2·DBP)/3 = DBP + PP/3, an estimate based on the heart spending about two thirds of each beat in diastole at a normal heart rate (less accurate when the heart rate is fast); a MAP of at least about 65 mmHg is a common target for organ perfusion. The shock index SI = heart rate/SBP is normally about 0.5–0.7; a value above about 1 is a warning sign of shock.
Shock index
SI = 133/82 = 1.622 ≈ 1.62
Answer
SI = 1.62
1 or more: a warning sign of shock in this practice case.
8.Clinical assessment scores
Answer: healthy weight
Body mass index: BMI = weight (kg)/height (m)², with the height converted to metres first. With pounds and inches, BMI = 703 × weight (lb)/height (in)². WHO adult categories: below 18.5 underweight, 18.5–24.9 healthy weight, 25.0–29.9 overweight, 30.0–34.9 obesity class I, 35.0–39.9 obesity class II and 40 or more obesity class III.
BMI
BMI = 81/1.83² = 24.19
Category
healthy weight
Answer
healthy weight
9.Enteral & parenteral nutrition calculations
Answer: %IBW = 147 %
Needs and free water: energy needs are often estimated as kcal/kg/day × weight and protein needs as g/kg/day × weight. A formula is only partly water, so its free water = volume × water fraction; water flushes make up the rest of the daily fluid goal. Ideal body weight (Devine): IBW = 50 kg + 2.3 kg for every inch over 5 feet (60 in) for men, and 45.5 kg + 2.3 kg per inch over 60 in for women; 1 in = 2.54 cm. The formula is meant for adults at least 152.4 cm (5 ft) tall. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Ideal body weight (Devine)
174 cm/2.54 = 68.5 in
IBW = 50 + 2.3·(68.5 − 60) = 69.56 kg
Percentage of ideal body weight
%IBW = 102/69.56·100 = 146.6 ≈ 147%
Answer
%IBW = 147%
10.Enteral & parenteral nutrition calculations
Answer: E = 880 kcal/day
Parenteral nutrition: dextrose provides 3.4 kcal/g, amino acids 4 kcal/g and lipid emulsion the kcal/mL stated (2 kcal/mL for 20%, 1.1 kcal/mL for 10%). Grams = % × mL/100. Non-protein kcal (NPC) = dextrose + lipid kcal; nitrogen = protein/6.25. The glucose infusion rate (GIR) in mg/kg/min = dextrose mg/(kg × minutes). The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Grams of dextrose and amino acids
dextrose: 15·1000/100 = 150 g
amino acids: 4.25·1000/100 = 42.5 g
Kilocalories per component
dextrose: 150·3.4 = 510 kcal
amino acids: 42.5·4 = 170 kcal
lipid: 100·2 = 200 kcal
Total energy
E = 510 + 170 + 200 = 880 kcal/day
Answer
E = 880 kcal/day
11.ECG rhythm strip interpretation
Answer: QTc = 0.38 s
QT and QTc: the QT interval runs from the start of the QRS complex to the end of the T wave. It shortens as the heart rate rises, so it is corrected for rate with the R–R interval in seconds: Bazett QTc = QT/√RR and Fridericia QTc = QT/∛RR. Bazett is the formula most textbooks use; it over-corrects at fast rates, where Fridericia is preferred. Limits differ between references: a QTc above about 0.45 s in men or 0.46 s in women is usually called prolonged, and above 0.50 s markedly prolonged.
Measure
QT = 8.5 × 0.04 = 0.34 s
RR = 20 × 0.04 = 0.80 s
Bazett’s formula
QTc = 0.34/√0.80 = 0.34/0.8944 = 0.38 s
Answer
QTc = 0.38 s
Within the usual limits (about 0.45 s for men, 0.46 s for women). (380 ms)
12.ECG rhythm strip interpretation
Answer: 2:1 AV block (type undetermined)
2:1 AV block: with two P waves for every QRS, no two conducted P waves follow each other, so you cannot see whether the PR would lengthen (type I) or stay constant (type II) before a non-conducted P wave. From one strip it is called a 2:1 AV block; a longer strip or a change in the conduction ratio decides the type. A narrow QRS makes type I more likely and a wide QRS type II, but neither proves it.
Five steps
1. Rate: R–R = 42 small boxes, 1500 ÷ 42 ≈ 36 per minute.
2. Rhythm: regular, every R–R is 1.68 s.
3. P waves: upright and regular (P–P 0.84 s, 71 per minute), two for every QRS.
4. PR interval: constant at 0.18 s in the conducted beats.
5. QRS: 0.12 s, wide (0.12 s or more).
Why the type stays open
Every second P wave is not conducted, so no two conducted beats follow each other and a lengthening PR could never show.
2:1 AV block (type undetermined)
Answer
2:1 AV block (type undetermined)
A narrow QRS makes type I more likely and a wide QRS type II, but only a longer strip or a change in the conduction ratio decides.
13.Prioritization & delegation
Answer: D · Increasing sleepiness that is hard to rouse
Why this is the answer
Sedation usually increases before breathing slows. Regular sedation checks let the nurse hold the opioid and act before respiratory depression occurs.
Answer
D · Increasing sleepiness that is hard to rouse
14.Prioritization & delegation
Answer: D · “I will rub the area after the injection to help it absorb.”
Why this is the answer
Rubbing the site after a low-molecular-weight heparin injection increases bruising. The abdomen away from the navel, rotating sites and reporting bleeding are correct.
Answer
D · “I will rub the area after the injection to help it absorb.”
15.Infection control & patient safety
Answer: D · Rinse the eyes at once with plenty of water or saline, then report
Why this is the answer
Mucous membranes are rinsed straight away with plenty of water or saline, for example at an eyewash station. The exposure is reported immediately so the risk can be assessed and post-exposure treatment considered.
Answer
D · Rinse the eyes at once with plenty of water or saline, then report
16.Infection control & patient safety
Answer: A · Be honest that an error occurred and involve the provider and team in disclosure per policy
Why this is the answer
Open, honest disclosure of errors is an ethical duty and part of a safety culture. The nurse follows policy, which usually involves the provider and risk team, and does not hide or blame.
Answer
A · Be honest that an error occurred and involve the provider and team in disclosure per policy
17.Lab values & electrolytes
Answer: D · Plasma volume rises more than red cell mass, diluting the blood
Why this is the answer
In pregnancy, plasma volume increases by more than red cell mass, so the hemoglobin falls slightly (physiologic or dilutional anemia). Iron deficiency is still common in pregnancy and is checked with the MCV and ferritin.Checked against:Anemia · StatPearls (NCBI Bookshelf) (2026)
Answer
D · Plasma volume rises more than red cell mass, diluting the blood
18.Lab values & electrolytes
Answer: C · Send a venous sample to the lab and inform the provider at once
Why this is the answer
"HI" means the glucose exceeds the meter's range, so the true value is unknown and may be very high, as in DKA or HHS. A laboratory sample is sent, the provider is informed promptly, and the patient is assessed for dehydration and ketones.Checked against:Blood Glucose Test · MedlinePlus (NIH) (2024); Diabetic ketoacidosis - Medical Encyclopedia · MedlinePlus (NIH) (2025)
Answer
C · Send a venous sample to the lab and inform the provider at once