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
Which measure is appropriate for a patient with a fever who feels hot and uncomfortable?
ALight bedclothes, plenty of fluids and a prescribed antipyretic
BRestricting fluids so the patient sweats less during the fever
CExtra blankets to make the patient sweat it out
DAn ice bath until the patient shivers
2.Nursing fundamentalsHard
During a handover the nurse notices a colleague is sharing patient details loudly in a busy corridor. What should the nurse do?
AJoin in to finish the handover more quickly
BIgnore it, as handover is part of care
CReport the colleague to the police
DSuggest moving the handover to a private place
3.Clinical nursingMedium
Which advice is correct for a patient taking levothyroxine?
ATake it on an empty stomach, usually before breakfast
BStop taking it once the symptoms improve
CTake it with a large meal to avoid nausea and stomach upset
DTake it only on days when feeling tired
4.Clinical nursingHard
Four call bells ring at the same time. Which patient should the nurse see first?
AA patient asking for pain relief for chronic back pain that they rate as 3/10
BA patient asking what time they will be discharged
CA patient who has just become breathless after starting an IV antibiotic
DA patient who needs help to go to the toilet and has rung twice
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 130 mmol/L, glucose 16 mmol/L and urea 10.8 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 130 mmol/Lglucose 16 mmol/Lurea 10.8 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
A practice gas shows a metabolic alkalosis with HCO₃⁻ 36 mmol/L. Use expected PaCO₂ = 0.7·HCO₃⁻ + 21 to find the expected PaCO₂.
HCO₃⁻ 36 mmol/L
PaCO₂ = mmHg
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 8/min, SpO₂ 89% on room air, blood pressure 112/68 mmHg, pulse 82/min, alert, temperature 38.4 °C. What is the NEWS2 total score?
RR 8SpO₂ 89%airSBP 112HR 82AT 38.4 °C
NEWS2 =
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 97% on room air, blood pressure 90/54 mmHg, pulse 120/min, alert, temperature 35.2 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). A 70 kg adult (BMI below 30) needs 35 kcal/kg/day. The tube feed provides 1 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). Over 24 hours a patient receives 1000 mL of parenteral nutrition with final concentrations of 20% dextrose and 4% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the total energy E the patient receives in kcal per day. Round to the nearest whole number.
1000 mLdextrose 20%amino acids 4%lipid 500 mL · 1.1 kcal/mL
E = kcal/day
11.ECG rhythm strip interpretationMedium
This lead II strip shows sinus rhythm with one pause. Measure the pause, the R–R interval across it, in seconds.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
pause = s
12.ECG rhythm strip interpretationHard
This lead II strip shows a conduction problem between the atria and the ventricles. 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
1third-degree (complete) AV block
2second-degree AV block type II
3second-degree AV block type I (Wenckebach)
4atrial fibrillation
13.Prioritization & delegationMedium
A patient taking clozapine reports a sore throat and fever. What is the priority action?
AAdvise the patient to gargle with warm salt water and rest in bed
BOffer throat lozenges and continue the usual dose
CIncrease the dose because the symptoms suggest a relapse
DHold the dose and report so the white cell count can be checked
14.Prioritization & delegationHard
A patient taking an SSRI is also given tramadol. A few hours later the patient is agitated, sweating and has a fever, jerking muscles and brisk reflexes. What is the most likely cause?
ANeuroleptic malignant syndrome
BSerotonin syndrome
CAn anxiety attack
DOpioid withdrawal
15.Infection control & patient safetyMedium
A patient’s identification wristband is missing. A medication is due. What should the nurse do?
AUse the room and bed number to confirm identity
BGive it, because the nurse recognizes the patient from yesterday
CSkip the medication until the next day
DConfirm identity with two identifiers and apply a new wristband first
16.Infection control & patient safetyHard
A nurse has just started a unit of red blood cells when a colleague asks for urgent help with another patient. What is the best action?
ASpeed up the transfusion so it finishes sooner
BPause the transfusion until the nurse is free again
CStay with the transfusing patient for the first 15 minutes and ask another nurse to help
DLeave to help the other patient, and check the transfusion again in about an hour
17.Lab values & electrolytesMedium
When do the blood counts usually reach their lowest point (nadir) after many standard chemotherapy regimens?
AWithin 1–2 hours of treatment
BOn the same day as treatment
CAbout 7–14 days after treatment
DAbout 6 months after treatment
18.Lab values & electrolytesHard
A patient with a long-standing lung condition has a serum bicarbonate of 32 mEq/L, an arterial PaCO₂ that is always high and a pH of 7.36. Which condition fits best?
AAcute severe diarrhea with large bicarbonate losses
BAcute diabetic ketoacidosis with severe dehydration and vomiting
CCOPD with chronic CO₂ retention and metabolic compensation
DAcute aspirin overdose with rapid breathing
3Solutions
1.Nursing fundamentals
Answer: A · Light bedclothes, plenty of fluids and a prescribed antipyretic
Why this is the answer
Light clothing, fluids and antipyretics such as paracetamol (acetaminophen) increase comfort and replace fluid lost through sweating. Very cold sponging causes shivering, which produces heat.
Answer
A · Light bedclothes, plenty of fluids and a prescribed antipyretic
2.Nursing fundamentals
Answer: D · Suggest moving the handover to a private place
Why this is the answer
Information shared for care must still be protected from people who do not need it. Moving to a private area or speaking quietly at the bedside protects patient confidentiality.
Answer
D · Suggest moving the handover to a private place
3.Clinical nursing
Answer: A · Take it on an empty stomach, usually before breakfast
Why this is the answer
Levothyroxine is absorbed best on an empty stomach and is usually taken at the same time each morning. It is normally lifelong, with doses adjusted by thyroid blood tests.
Answer
A · Take it on an empty stomach, usually before breakfast
4.Clinical nursing
Answer: C · A patient who has just become breathless after starting an IV antibiotic
Why this is the answer
Breathlessness soon after a new IV antibiotic suggests possible anaphylaxis, an airway and breathing emergency. The infusion should be stopped and the patient assessed immediately.
Answer
C · A patient who has just become breathless after starting an IV antibiotic
5.Arterial blood gas interpretation
Answer: Osm = 287 mOsm/kg
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.
Calculated osmolality
Osm = 2·130 + 16 + 10.8 = 286.8 ≈ 287 mOsm/kg
Answer
Osm = 287 mOsm/kg
6.Arterial blood gas interpretation
Answer: PaCO₂ = 46.2 mmHg
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
0.7·36 + 21 = 46.2 mmHg
Answer
PaCO₂ = 46.2 mmHg
The rise has a limit: PaCO₂ rarely goes above about 55 mmHg from compensation alone.
7.Clinical assessment scores
Answer: NEWS2 = 7
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 8/min → 3
SpO₂ 89% → 3
on air → 0
SBP 112 mmHg → 0
HR 82/min → 0
alert (A) → 0
T 38.4 °C → 1
Add
NEWS2 = 3 + 3 + 0 + 0 + 0 + 0 + 1 = 7
Answer
NEWS2 = 7
8.Clinical assessment scores
Answer: 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 97% → 0
on air → 0
SBP 90 mmHg → 3
HR 120/min → 2
alert (A) → 0
T 35.2 °C → 1
Total and red scores
NEWS2 = 0 + 0 + 0 + 3 + 2 + 0 + 1 = 6
At least one parameter scores 3.
Risk group
medium
Answer
medium
A total of 5 or more calls for an urgent clinical response.
9.Enteral & parenteral nutrition calculations
Answer: R = 153 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 = 35·70 = 2450 kcal/day
Daily volume
V = 2450/1 = 2450 mL/day
Pump rate
R = 2450/16 = 153.1 ≈ 153 mL/h
Answer
R = 153 mL/h
10.Enteral & parenteral nutrition calculations
Answer: E = 1390 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: 20·1000/100 = 200 g
amino acids: 4·1000/100 = 40 g
Kilocalories per component
dextrose: 200·3.4 = 680 kcal
amino acids: 40·4 = 160 kcal
lipid: 500·1.1 = 550 kcal
Total energy
E = 680 + 160 + 550 = 1390 kcal/day
Answer
E = 1390 kcal/day
11.ECG rhythm strip interpretation
Answer: pause = 2 s
Narrow-complex tachycardia and pauses: supraventricular tachycardia (SVT) is a regular tachycardia at about 150–250/min with narrow QRS complexes; the P waves are usually not visible because they are hidden in the QRS complex or the T wave. Sinus tachycardia in an adult at rest is usually below about 150/min and has a visible P wave before every QRS; atrial flutter with 2:1 conduction often runs at about 150/min and shows sawtooth waves. In sinus arrest the sinus node stops firing for a moment: a pause with no P wave and no QRS whose length is not a whole number of P–P cycles (a pause of exactly two or three cycles points to sinus exit block instead).
Measure
50 small boxes from R to R across the pause
Convert
pause = 50 × 0.04 s = 2 s
Compare with P–P
2.00 ÷ 0.88 ≈ 2.3 P–P cycles, not a whole number
Answer
pause = 2 s
No P wave appears in the pause, and the pause is not a whole number of P–P cycles: sinus arrest. A pause of exactly two or three cycles would point to sinus exit block.
12.ECG rhythm strip interpretation
Answer: second-degree AV block type I (Wenckebach)
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.
Five steps
1. Rate: 4 QRS complexes in 6 s, × 10 = 40 per minute.
2. Rhythm: regularly irregular, the QRS complexes come in groups separated by a pause (group beating).
3. P waves: upright and regular (P–P 0.96 s, 63 per minute); one P in every 3 is not followed by a QRS.
4. PR interval: lengthens 0.20 → 0.32 s, then a P wave is not conducted.
5. QRS: 0.06 s, narrow (below 0.12 s).
Interpretation
second-degree AV block type I (Wenckebach)
Answer
second-degree AV block type I (Wenckebach)
13.Prioritization & delegation
Answer: D · Hold the dose and report so the white cell count can be checked
Why this is the answer
Clozapine can cause agranulocytosis. A sore throat or fever may be the first sign of infection, so the nurse reports it and the neutrophil count is checked before more doses are given.
Answer
D · Hold the dose and report so the white cell count can be checked
14.Prioritization & delegation
Answer: B · Serotonin syndrome
Why this is the answer
SSRIs and tramadol both raise serotonin. Agitation, fever, clonus and hyperreflexia that start quickly suggest serotonin syndrome; neuroleptic malignant syndrome follows antipsychotics and causes rigid muscles with slow reflexes.
Answer
B · Serotonin syndrome
15.Infection control & patient safety
Answer: D · Confirm identity with two identifiers and apply a new wristband first
Why this is the answer
Every medication requires a confirmed identity. The nurse replaces the wristband after confirming the patient’s identity with two identifiers. Familiarity and room numbers are not acceptable identifiers.
Answer
D · Confirm identity with two identifiers and apply a new wristband first
16.Infection control & patient safety
Answer: C · Stay with the transfusing patient for the first 15 minutes and ask another nurse to help
Why this is the answer
The most serious reactions, such as acute hemolytic reactions and anaphylaxis, usually start within the first 15 minutes. The nurse stays with the patient during this time and finds another person to help elsewhere.
Answer
C · Stay with the transfusing patient for the first 15 minutes and ask another nurse to help
17.Lab values & electrolytes
Answer: C · About 7–14 days after treatment
Why this is the answer
Chemotherapy damages dividing marrow cells, but mature neutrophils and platelets already in the blood survive for a while, so counts usually fall to a nadir about 7–14 days later, depending on the drug. Infection and bleeding risks are highest then.
Answer
C · About 7–14 days after treatment
18.Lab values & electrolytes
Answer: C · COPD with chronic CO₂ retention and metabolic compensation
Why this is the answer
In chronic CO₂ retention, as in severe COPD, the kidneys retain bicarbonate over days and bring the pH back towards normal, often to the low end of the range. DKA and diarrhea lower bicarbonate, and aspirin overdose causes rapid breathing that lowers the PaCO₂.Checked against:Respiratory Acidosis · StatPearls (NCBI Bookshelf)
Answer
C · COPD with chronic CO₂ retention and metabolic compensation