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
What is the main purpose of a wound drain after surgery?
ATo keep the wound edges apart until it heals
BTo give antibiotics directly into the wound until it has fully healed
CTo measure the temperature inside the wound
DTo remove fluid or blood that could collect and delay healing
2.Nursing fundamentalsHard
A patient has had a stroke. Why must swallowing be screened before giving food, drink or oral medicine?
ASwallowing checks are only needed if the patient asks
BPatients after a stroke are always kept nil by mouth for at least a week
COral medicines are never used after a stroke
DDysphagia is common after stroke and can cause aspiration pneumonia
3.Clinical nursingMedium
A nurse gives a patient analgesia for post-operative pain. What should be done next?
AWait until the next shift before asking the patient about the pain
BAssume the pain has gone if the patient is quiet and has their eyes closed
CGive a second analgesic straight away just in case
DReassess the pain and any side effects once the drug has had time to work
4.Clinical nursingHard
A patient has new facial weakness. Which feature suggests a stroke rather than Bell's palsy?
AThe patient has had a recent cold
BThe patient has pain behind the ear
CThe forehead can still be wrinkled on the affected side
DThe whole of one side of the face, including the forehead, is weak
5.Arterial blood gas interpretationMedium
A practice arterial blood gas shows pH 7.50, PaCO₂ 20 mmHg (2.7 kPa) and HCO₃⁻ 15 mmol/L. The primary disorder is respiratory alkalosis. How far is it compensated? Click your answer.
pH 7.50PaCO₂ 20 mmHg (2.7 kPa)HCO₃⁻ 15 mmol/L
1uncompensated
2partially compensated
3fully compensated
6.Arterial blood gas interpretationHard
A practice gas shows a metabolic acidosis: pH 7.15, PaCO₂ 50 mmHg (6.7 kPa), HCO₃⁻ 17 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.
pH 7.15PaCO₂ 50 mmHg (6.7 kPa)HCO₃⁻ 17 mmol/L
1appropriate compensation
2added respiratory acidosis
3added respiratory alkalosis
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 18/min, SpO₂ 96% on room air, blood pressure 150/90 mmHg, pulse 114/min, alert, temperature 38.1 °C. What is the NEWS2 total score?
RR 18SpO₂ 96%airSBP 150HR 114AT 38.1 °C
NEWS2 =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). An adult weighs 88 kg and is 160 cm tall. Calculate the BMI and click the WHO weight category.
Practice exercise (made-up values, not clinical guidance). A 58 kg adult (BMI below 30) needs 35 kcal/kg/day. The tube feed provides 1.2 kcal/mL and runs by pump for 16 hours a day. At what rate R do you set the pump, in mL/h? Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). An 84 kg adult receives 1800 mL of parenteral nutrition containing 12.5% dextrose, infused over 24 hours. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
84 kg1800 mLdextrose 12.5%24 h
GIR = mg/kg/min
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
This lead II strip shows second-degree AV block type I (Wenckebach). By how much does the PR interval increase from the first to the second beat of a group (ΔPR), in seconds?
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
ΔPR = s
13.Prioritization & delegationMedium
A nurse gives IV morphine for severe pain. When should the nurse reassess the pain and sedation?
AAt the next routine round in four hours
BOnly when the patient asks for more
CAt the end of the shift
DWithin about 15–30 minutes
14.Prioritization & delegationHard
A toddler with tetralogy of Fallot becomes very blue and breathless while crying. What should the nurse do first?
APlace the child in a knee-to-chest position
BEncourage the child to keep crying to open the lungs
CLay the child flat on their back
DGive a large drink of water to calm the child
15.Infection control & patient safetyMedium
Sterile saline is spilled on a sterile drape that lies on a non-sterile table. What does this mean?
AOnly the wet part is contaminated, so items can be moved to the dry part
BThe field stays sterile, because saline is sterile
CThe field becomes sterile again when it dries
DThe field is contaminated, because moisture can carry organisms through the drape
16.Infection control & patient safetyHard
A unit keeps vials of concentrated potassium chloride in the ward stock cupboard. Why do many safety guidelines advise against this?
APotassium chloride is too expensive to keep as general ward stock
BUndiluted concentrate given by mistake can stop the heart
CPotassium chloride vials expire within a day of opening
DPotassium chloride must always be given by mouth
17.Lab values & electrolytesMedium
A patient with central diabetes insipidus starts desmopressin. Which laboratory result is most important to monitor for an adverse effect?
ASerum calcium, which may rise too high
BSerum potassium, which may rise too high
CSerum glucose, which may rise very high
DSerum sodium, which may fall too low
18.Lab values & electrolytesHard
After surgery, a patient receiving large volumes of hypotonic IV fluid develops headache, nausea and confusion. Which result best explains this?
AA sodium of 126 mEq/L
BA glucose of 110 mg/dL (6.1 mmol/L)
CA calcium of 9.4 mg/dL (2.35 mmol/L)
DA potassium of 4.2 mEq/L
3Solutions
1.Nursing fundamentals
Answer: D · To remove fluid or blood that could collect and delay healing
Why this is the answer
Drains let blood, serous fluid or pus escape, preventing collections such as seromas and haematomas. The nurse records the amount and type of drainage.
Answer
D · To remove fluid or blood that could collect and delay healing
2.Nursing fundamentals
Answer: D · Dysphagia is common after stroke and can cause aspiration pneumonia
Why this is the answer
Stroke often affects swallowing, and silent aspiration is possible. A swallow screen, with referral to a speech and language therapist if needed, guides safe food textures and routes for medicines.
Answer
D · Dysphagia is common after stroke and can cause aspiration pneumonia
3.Clinical nursing
Answer: D · Reassess the pain and any side effects once the drug has had time to work
Why this is the answer
The effect of analgesia should be reassessed when it is expected to work, with side effects such as sedation and breathing checked. The result is documented and the plan adjusted.
Answer
D · Reassess the pain and any side effects once the drug has had time to work
4.Clinical nursing
Answer: C · The forehead can still be wrinkled on the affected side
Why this is the answer
In a stroke (upper motor neurone lesion), the forehead is usually spared because it has bilateral cortical supply. Bell's palsy (lower motor neurone) weakens the whole side, including the forehead.
Answer
C · The forehead can still be wrinkled on the affected side
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 7.50: alkalaemia (above 7.45)
PaCO₂ 20 mmHg: low (35–45)
HCO₃⁻ 15 mmol/L: low (22–26)
Compensation
partially compensated
Answer
partially compensated
6.Arterial blood gas interpretation
Answer: added respiratory acidosis
Expected compensation: in metabolic acidosis Winter’s formula predicts PaCO₂ = 1.5·HCO₃⁻ + 8 ± 2 mmHg; a measured value above that range points to an additional respiratory acidosis, below it to an additional respiratory alkalosis. The anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), normally about 8–12 mmol/L, separates high-gap from normal-gap metabolic acidosis; low albumin hides a high gap (add 2.5 per g/dL that albumin is below 4.0). The delta ratio (AG − 12)/(24 − HCO₃⁻) between about 0.8 and 2 fits a pure high-gap acidosis (some texts use 1 instead of 0.8), below that an added normal-gap acidosis, and above 2 an added metabolic alkalosis.
Expected PaCO₂
1.5·17 + 8 = 33.5 → 31.5–35.5 mmHg
Compare
measured: 50 mmHg → added respiratory acidosis
Answer
added respiratory acidosis
7.Clinical assessment scores
Answer: NEWS2 = 3
NEWS2 (National Early Warning Score 2, Royal College of Physicians 2017): score each of the seven parameters with the chart (respiration rate, SpO₂ on scale 1, air or supplemental oxygen, systolic blood pressure, pulse, consciousness on the ACVPU scale and temperature) and add the scores. Clinical risk: 0–4 low; a score of 3 in any single parameter low–medium; 5–6 medium; 7 or more high. A total of 5 or more needs an urgent response.
Score each parameter
RR 18/min → 0
SpO₂ 96% → 0
on air → 0
SBP 150 mmHg → 0
HR 114/min → 2
alert (A) → 0
T 38.1 °C → 1
Add
NEWS2 = 0 + 0 + 0 + 0 + 2 + 0 + 1 = 3
Answer
NEWS2 = 3
8.Clinical assessment scores
Answer: obesity class I
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 = 88/1.6² = 34.37
Category
obesity class I
Answer
obesity class I
9.Enteral & parenteral nutrition calculations
Answer: R = 106 mL/h
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.
Energy needed
E = 35·58 = 2030 kcal/day
Daily volume
V = 2030/1.2 = 1692 mL/day
Pump rate
R = 1692/16 = 105.7 ≈ 106 mL/h
Answer
R = 106 mL/h
10.Enteral & parenteral nutrition calculations
Answer: GIR = 1.86 mg/kg/min
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.
Dextrose in the bag
12.5·1800/100 = 225 g = 225 000 mg
Minutes of infusion
24·60 = 1440 min
Glucose infusion rate
GIR = 225 000/(84·1440) = 1.86 mg/kg/min
Answer
GIR = 1.86 mg/kg/min
11.ECG rhythm strip interpretation
Answer: QTc = 0.481 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 = 12.5 × 0.04 = 0.50 s
RR = 27 × 0.04 = 1.08 s
Bazett’s formula
QTc = 0.50/√1.08 = 0.50/1.039 = 0.481 s
Answer
QTc = 0.481 s
Above the usual limits for both men (about 0.45 s) and women (about 0.46 s): prolonged. (481 ms)
12.ECG rhythm strip interpretation
Answer: ΔPR = 0.12 s
AV blocks: march out the P waves and check which ones are followed by a QRS. First-degree: every P conducted, PR constant and above 0.20 s. Second-degree type I (Mobitz I, Wenckebach): the PR lengthens from beat to beat until one P wave is not conducted, then the cycle starts again (group beating). Second-degree type II (Mobitz II): the PR of the conducted beats stays constant, and P waves are suddenly not conducted; the QRS is often wide. Third-degree (complete) block: P waves and QRS complexes are each regular but independent, the PR varies at random and the atrial rate is faster than the escape rate (junctional 40–60/min with a narrow QRS, ventricular 20–40/min with a wide QRS). A 2:1 block cannot be called type I or type II from one strip.
March out the P waves
P–P = 0.88 s, regular; one P wave in every 4 is not conducted
PR in each group
PR₁ = 0.16 s, PR₂ = 0.28 s, PR₃ = 0.36 s
Answer
ΔPR = 0.12 s
The biggest step in PR comes between the first and second beats of a group; later steps are smaller, which is why the R–R intervals shorten before the pause.
13.Prioritization & delegation
Answer: D · Within about 15–30 minutes
Why this is the answer
IV opioids act within minutes, so the nurse reassesses pain, sedation and breathing within about 15–30 minutes. Oral analgesics are usually reassessed later, after about an hour.
Answer
D · Within about 15–30 minutes
14.Prioritization & delegation
Answer: A · Place the child in a knee-to-chest position
Why this is the answer
In a hypercyanotic (“tet”) spell, the knee-chest position raises systemic vascular resistance and sends more blood to the lungs. Oxygen and prescribed medication follow.
Answer
A · Place the child in a knee-to-chest position
15.Infection control & patient safety
Answer: D · The field is contaminated, because moisture can carry organisms through the drape
Why this is the answer
Liquid soaking through a drape can carry organisms up from the non-sterile surface below. The field is considered contaminated and is set up again.
Answer
D · The field is contaminated, because moisture can carry organisms through the drape
16.Infection control & patient safety
Answer: B · Undiluted concentrate given by mistake can stop the heart
Why this is the answer
Concentrated potassium chloride given undiluted or too quickly can stop the heart. Removing the concentrate from general ward stock and using premixed, ready-to-use bags is a widely recommended safety measure.
Answer
B · Undiluted concentrate given by mistake can stop the heart
17.Lab values & electrolytes
Answer: D · Serum sodium, which may fall too low
Why this is the answer
Desmopressin acts like ADH, so the kidneys retain water. If the patient drinks too much, water retention can cause hyponatremia, which may lead to confusion and seizures. Sodium, weight and fluid balance are monitored.
Answer
D · Serum sodium, which may fall too low
18.Lab values & electrolytes
Answer: A · A sodium of 126 mEq/L
Why this is the answer
Surgical stress raises antidiuretic hormone, and hypotonic fluids add free water, so sodium falls. Hyponatremia causes headache, nausea and confusion. The other values are normal.Checked against:Low blood sodium · MedlinePlus (NIH) (2025); Syndrome of inappropriate antidiuretic hormone secretion · MedlinePlus (NIH) (2025); Hyponatremia · StatPearls (NCBI Bookshelf)