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
Before fitting anti-embolism stockings, what should the nurse do?
AFit the tightest size available so the stockings give the best effect
BFit them over existing bandages or wounds
CMeasure the legs to get the right size and check for arterial disease
DChoose a size by looking at the patient's shoe size and weight
2.Nursing fundamentalsHard
After treatment for hypoglycaemia a patient's glucose is now 5.2 mmol/L (94 mg/dL) and the next meal is hours away. What should the nurse do next?
AGive another dose of insulin to balance out the extra sugar
BGive nothing more, as the glucose is now normal
CGive a longer-acting carbohydrate, such as a sandwich
DGive a second glucose drink every 15 minutes
3.Clinical nursingMedium
Why must levodopa for Parkinson's disease be given at the exact times prescribed in hospital?
AThe drug only works if taken at midnight
BEarly doses cause severe low blood glucose and sweating attacks
CLate doses cause dangerous high potassium
DDelays can quickly worsen rigidity, immobility and swallowing
4.Clinical nursingHard
An older patient's blood pressure is 142/80 mmHg lying and 116/72 mmHg after standing for three minutes, and they feel dizzy. What does this show?
AHypertensive emergency
BWhite coat hypertension
CPostural hypotension
DNormal blood pressure variation
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 73 mmHg (9.7 kPa). Use the rule that in chronic respiratory acidosis HCO₃⁻ rises by 3.5 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
At sea level, a practice gas taken on 30% oxygen shows PaO₂ 62 mmHg (8.3 kPa) and PaCO₂ 44 mmHg (5.9 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.
Practice exercise (made-up values, not clinical guidance). A practice chart records GCS 4, with E1 and V1. What motor score M was recorded, and which response does it describe? Give the number.
GCS 4E1V1
M =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 18/min, SpO₂ 88% on room air, blood pressure 142/86 mmHg, pulse 70/min, alert, temperature 37.3 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). A 51 kg patient has a fluid goal of 35 mL/kg/day and receives all fluid through a feeding tube. The formula is 70% free water and runs at 90 mL/h for 24 hours a day. The rest of the fluid is given as water flushes every 4 hours. What volume V is each flush? Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 1200 mL of parenteral nutrition with final concentrations of 10% dextrose and 3.5% 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.
1200 mLdextrose 10%amino acids 3.5%lipid 100 mL · 2 kcal/mL
E = kcal/day
11.ECG rhythm strip interpretationMedium
Interpret this lead II rhythm strip. Which rhythm is it? 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
1first-degree AV block
2sinus bradycardia
3junctional rhythm
4normal sinus rhythm
12.ECG rhythm strip interpretationHard
This lead II strip shows an AV block, so the atria and the ventricles beat at different rates. The QRS complexes are regular: find the ventricular rate in beats per minute (1500 method, whole number).
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
ventricular rate = bpm
13.Prioritization & delegationMedium
A nurse gives IV morphine for severe pain. When should the nurse reassess the pain and sedation?
AWithin about 15–30 minutes
BAt the end of the shift
COnly when the patient asks for more
DAt the next routine round in four hours
14.Prioritization & delegationHard
During START triage, a non-walking adult breathes 28 times a minute, has no radial pulse and has a capillary refill of 4 seconds. Which category is the victim given?
ABlack (expectant)
BGreen (minor)
CRed (immediate)
DYellow (delayed), because the respiratory rate is under 30/min
15.Infection control & patient safetyMedium
A nurse pours sterile saline into a bowl on a sterile field. Which technique is correct?
AReach across the field to fill the bowl at the far side
BHold the bottle with the label in the palm and pour without touching the bowl
CPour from below the level of the field to reduce splashing
DRest the lip of the bottle on the edge of the bowl so that the saline does not splash
16.Infection control & patient safetyHard
A newly hired nurse has these hepatitis B results: HBsAg negative, anti-HBs positive, anti-HBc negative. What do they show?
AA current hepatitis B infection
BImmunity from hepatitis B vaccination
CPast infection that has now cleared
DNo immunity, so the vaccine is needed
17.Lab values & electrolytesMedium
Which factor is most likely to raise a patient’s lithium level?
ATaking each dose with a meal instead of before
BEating more salt than usual for several days
CDrinking more fluid than usual in hot weather
DDehydration or a sudden drop in sodium intake
18.Lab values & electrolytesHard
A patient on a heparin infusion has a platelet count that falls from 260 to 110 × 10³/µL on day 7. Which action is most appropriate?
ATake no action, because the count is still just above 100 × 10³/µL
BReport it at once: heparin-induced thrombocytopenia is possible
CContinue the infusion and increase the rate as per protocol
DGive a platelet transfusion and continue the heparin
3Solutions
1.Nursing fundamentals
Answer: C · Measure the legs to get the right size and check for arterial disease
Why this is the answer
Wrong-sized stockings can cause skin damage or a tourniquet effect. They are not used in significant peripheral arterial disease, and the skin is checked daily.
Answer
C · Measure the legs to get the right size and check for arterial disease
2.Nursing fundamentals
Answer: C · Give a longer-acting carbohydrate, such as a sandwich
Why this is the answer
Fast-acting glucose raises the level quickly but briefly. A starchy snack, or the next meal if due, keeps it from falling again. The episode is recorded and its cause reviewed.
Answer
C · Give a longer-acting carbohydrate, such as a sandwich
3.Clinical nursing
Answer: D · Delays can quickly worsen rigidity, immobility and swallowing
Why this is the answer
Levodopa has a short effect, so missed or late doses can lead to severe stiffness, falls, swallowing problems and, rarely, a dangerous hyperpyrexia-like state. Parkinson's medicines are treated as time-critical.
Answer
D · Delays can quickly worsen rigidity, immobility and swallowing
4.Clinical nursing
Answer: C · Postural hypotension
Why this is the answer
A fall in systolic pressure of 20 mmHg or more (here 26 mmHg) on standing, especially with symptoms, indicates postural hypotension. Causes include medicines, dehydration and autonomic problems.
Answer
C · Postural hypotension
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 35.55 mmol/L
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.
Change in PaCO₂
|73 − 40| = 33 mmHg → 3.3 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 3.5·3.3 = 35.55 mmol/L
Answer
HCO₃⁻ = 35.55 mmol/L
6.Arterial blood gas interpretation
Answer: A–a gradient = 96.9 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.
Alveolar oxygen
PAO₂ = 0.3·713 − 44/0.8 = 213.9 − 55 = 158.9 mmHg
Gradient
A–a = 158.9 − 62 = 96.9 mmHg
Answer
A–a gradient = 96.9 mmHg
7.Clinical assessment scores
Answer: M = 2
Glasgow Coma Scale: add the best response in three areas. Eye opening E: 4 spontaneous, 3 to sound or speech, 2 to pressure, 1 none. Verbal V: 5 oriented, 4 confused, 3 inappropriate words, 2 incomprehensible sounds, 1 none. Motor M: 6 obeys commands, 5 localises, 4 normal flexion (withdraws), 3 abnormal flexion, 2 extension, 1 none. The total runs from 3 to 15. After a head injury, 13–15 is usually called mild, 9–12 moderate and 3–8 severe.
Motor score
M = 4 − 1 − 1 = 2
M2: extension of the arms and legs (abnormal extension)
Answer
M = 2
8.Clinical assessment scores
Answer: low–medium
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 88% → 3
on air → 0
SBP 142 mmHg → 0
HR 70/min → 0
alert (A) → 0
T 37.3 °C → 0
Total and red scores
NEWS2 = 0 + 3 + 0 + 0 + 0 + 0 + 0 = 3
At least one parameter scores 3.
Risk group
low–medium
Answer
low–medium
A single score of 3 needs an urgent review even when the total is low.
9.Enteral & parenteral nutrition calculations
Answer: V = 46 mL
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.
Fluid goal
35·51 = 1785 mL/day
Free water from the formula
90·24 = 2160 mL
2160·0.7 = 1512 mL
Water still needed
1785 − 1512 = 273 mL/day
Volume per flush
24/4 = 6 flushes
V = 273/6 = 45.5 ≈ 46 mL
Answer
V = 46 mL
10.Enteral & parenteral nutrition calculations
Answer: E = 776 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: 10·1200/100 = 120 g
amino acids: 3.5·1200/100 = 42 g
Kilocalories per component
dextrose: 120·3.4 = 408 kcal
amino acids: 42·4 = 168 kcal
lipid: 100·2 = 200 kcal
Total energy
E = 408 + 168 + 200 = 776 kcal/day
Answer
E = 776 kcal/day
11.ECG rhythm strip interpretation
Answer: first-degree AV block
Rhythm criteria (lead II): sinus rhythm has an upright P wave before every QRS, a constant PR of 0.12–0.20 s and a narrow QRS: normal sinus rhythm at 60–100/min, sinus bradycardia below 60, sinus tachycardia above 100. Atrial fibrillation: no P waves, a fibrillatory baseline and an irregularly irregular R–R. Atrial flutter: sawtooth flutter waves at about 250–350/min with a fixed conduction ratio such as 2:1 or 4:1. First-degree AV block: sinus rhythm with a constant PR above 0.20 s. Junctional rhythm: narrow QRS at 40–60/min with absent or inverted P waves (PR below 0.12 s, or P after the QRS). A PVC is an early, wide (0.12 s or more), bizarre QRS without a P wave, with the T wave in the opposite direction and usually a full compensatory pause; in bigeminy every second beat is a PVC.
Five steps
1. Rate: R–R = 24 small boxes, 1500 ÷ 24 ≈ 63 per minute.
2. Rhythm: regular, every R–R is 0.96 s.
3. P waves: upright, one before every QRS, all alike.
4. PR interval: 0.28 s, constant, longer than 0.20 s.
5. QRS: 0.08 s, narrow (below 0.12 s).
Interpretation
first-degree AV block
Answer
first-degree AV block
12.ECG rhythm strip interpretation
Answer: ventricular rate = 34 bpm
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.
Atrial rate
P–P = 20 small boxes = 0.80 s → 1500 ÷ 20 = 75 ≈ 75 per minute
Ventricular rate
R–R = 44 small boxes = 1.76 s → 1500 ÷ 44 = 34.09 ≈ 34 per minute
Answer
ventricular rate = 34 bpm
Answer
ventricular rate = 34 bpm
Third-degree block with a wide-complex ventricular escape (usually 20–40 per minute).
13.Prioritization & delegation
Answer: A · 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
A · Within about 15–30 minutes
14.Prioritization & delegation
Answer: C · Red (immediate)
Why this is the answer
A rate under 30/min passes the breathing check, but an absent radial pulse or a capillary refill over 2 seconds fails the perfusion check, so the victim is immediate (red). Stopping after the breathing check is the trap.
Answer
C · Red (immediate)
15.Infection control & patient safety
Answer: B · Hold the bottle with the label in the palm and pour without touching the bowl
Why this is the answer
The nurse pours from a little height without touching the sterile bowl, avoiding splashes that would wet the field. Holding the label in the palm keeps it readable and free of drips.
Answer
B · Hold the bottle with the label in the palm and pour without touching the bowl
16.Infection control & patient safety
Answer: B · Immunity from hepatitis B vaccination
Why this is the answer
The vaccine contains surface antigen, so it produces anti-HBs only. A negative anti-HBc shows there has been no natural infection, and a negative HBsAg rules out current infection.
Answer
B · Immunity from hepatitis B vaccination
17.Lab values & electrolytes
Answer: D · Dehydration or a sudden drop in sodium intake
Why this is the answer
When the body is short of sodium or water, the kidneys keep more sodium and lithium with it, so the level rises. NSAIDs, thiazide diuretics and ACE inhibitors can also raise lithium levels.
Answer
D · Dehydration or a sudden drop in sodium intake
18.Lab values & electrolytes
Answer: B · Report it at once: heparin-induced thrombocytopenia is possible
Why this is the answer
Heparin-induced thrombocytopenia causes a large fall in platelets (often more than half), usually 5–14 days after starting heparin, and carries a high risk of clots. The prescriber stops all heparin and starts a non-heparin anticoagulant if HIT is suspected.Checked against:Heparin-Induced Thrombocytopenia · StatPearls (NCBI Bookshelf) (2023)
Answer
B · Report it at once: heparin-induced thrombocytopenia is possible