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 patient with advanced dementia cannot describe their pain. How should pain be assessed?
ABy using the 0–10 numeric rating scale only
BWith an observational pain tool that scores behaviour such as facial expression
CBy asking a visitor to guess the pain score
DBy assuming there is no pain as long as the patient does not complain or call for help
2.Nursing fundamentalsHard
When is a "clean" (non-sterile) technique acceptable instead of an aseptic technique?
AFor dressing a fresh surgical wound in theatre, provided that non-sterile gloves are worn throughout
BFor procedures that do not enter sterile body areas, such as giving an oral medicine
CFor inserting a central venous catheter
DFor inserting a urinary catheter
3.Clinical nursingMedium
A patient is receiving enteral feeding through a nasogastric tube. How should they be positioned during feeding?
AIn any position, as long as the feed runs slowly
BWith the head of the bed raised to at least 30 degrees
CLying on the left side with the head down to help the feed drain
DLying completely flat
4.Clinical nursingHard
In a patient with a head injury, which is usually the earliest sign of rising intracranial pressure?
AA slow pulse with high blood pressure
BA change in level of consciousness
CA fixed, dilated pupil on both sides
DIrregular breathing pauses
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 60 mmHg (8.0 kPa). Use the rule that in acute respiratory acidosis HCO₃⁻ rises by 1 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
A practice gas shows pH 7.32, PaCO₂ 36 mmHg (4.8 kPa) and HCO₃⁻ 18 mmol/L, with Na⁺ 143 and Cl⁻ 97 mmol/L. Use the anion gap and the delta ratio to click the best interpretation.
Practice exercise (made-up values, not clinical guidance). A patient has a pulse of 110/min and a blood pressure of 163/106 mmHg. Find the shock index SI = HR/SBP. Round to two decimal places.
HR 110/minBP 163/106 mmHg
SI =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 9/min, SpO₂ 99% on room air, blood pressure 150/90 mmHg, pulse 76/min, alert, temperature 36.8 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). An 80 kg patient needs 1.2 g of protein per kg a day. The tube feed contains 55 g of protein per litre and runs at 55 mL/h for 18 hours a day. How many grams of extra protein ΔP a day are still needed? Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 2400 mL of parenteral nutrition with final concentrations of 15% dextrose and 5% amino acids, plus 500 mL of 20% lipid emulsion (2 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
2400 mLdextrose 15%amino acids 5%lipid 500 mL · 2 kcal/mL
NPC : N =
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
Identify the rhythm on this lead II 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
1third-degree (complete) AV block
2ventricular fibrillation
3asystole
4sinus bradycardia
13.Prioritization & delegationMedium
A patient with a head injury is being monitored. Which set of findings suggests rising intracranial pressure?
ALow temperature, fast breathing and a strong appetite
BNormal blood pressure, normal pulse and clear speech
CRising systolic pressure, slow pulse and irregular breathing
DFalling blood pressure, a fast pulse and warm, flushed dry skin
14.Prioritization & delegationHard
A patient with raised intracranial pressure is being nursed on the ward. Which position is best?
AHead down with the legs raised above the heart
BFlat on the back with the head turned well over to one side
CHead of the bed at about 30 degrees with the neck straight
DSitting forward with the chin on the chest
15.Infection control & patient safetyMedium
When should blood specimen tubes be labeled?
AAt the nurses’ station before going to the patient, to save time
BBack at the station after all the samples are collected
CAt the bedside, in front of the patient, right after collection
DBy the laboratory staff after the tubes arrive
16.Infection control & patient safetyHard
The fire alarm sounds, but the nurse does not know where the fire is. What should the nurse do?
AOpen all doors so patients can be seen easily
BClose the doors to patient rooms, stay on the unit and wait for instructions
CEvacuate all patients down the stairs at once, starting with those in bed
DLeave the unit and the building to find out where the fire is
17.Lab values & electrolytesMedium
Before giving prescribed IV potassium chloride, which assessment is most important?
AHearing in both ears
BUrine output and kidney function
CSkin turgor on the forearm
DPupil size and reaction to light
18.Lab values & electrolytesHard
A patient on stable digoxin starts amiodarone. A week later, the patient has nausea and visual changes, and the digoxin level is above the range. What is the most likely explanation?
AAmiodarone has raised the digoxin level
BThe patient has started a viral illness
CAmiodarone has lowered potassium only
DDigoxin has raised the amiodarone level
3Solutions
1.Nursing fundamentals
Answer: B · With an observational pain tool that scores behaviour such as facial expression
Why this is the answer
Observational tools score signs such as facial expression, vocalisation, body language and changes in behaviour. People with dementia often have pain that is missed.
Answer
B · With an observational pain tool that scores behaviour such as facial expression
2.Nursing fundamentals
Answer: B · For procedures that do not enter sterile body areas, such as giving an oral medicine
Why this is the answer
Aseptic technique is required when entering normally sterile sites or handling key parts of invasive devices. Routine non-invasive tasks only need standard precautions.
Answer
B · For procedures that do not enter sterile body areas, such as giving an oral medicine
3.Clinical nursing
Answer: B · With the head of the bed raised to at least 30 degrees
Why this is the answer
Keeping the head raised to at least 30–45° during feeding and for a period afterwards lowers the risk of aspiration pneumonia.
Answer
B · With the head of the bed raised to at least 30 degrees
4.Clinical nursing
Answer: B · A change in level of consciousness
Why this is the answer
Subtle changes in consciousness, such as restlessness, confusion or a falling GCS, are often the first signs. Pupil changes and Cushing's triad (hypertension, bradycardia, irregular breathing) are late signs.
Answer
B · A change in level of consciousness
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 26 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
|60 − 40| = 20 mmHg → 2 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 1·2 = 26 mmol/L
Answer
HCO₃⁻ = 26 mmol/L
6.Arterial blood gas interpretation
Answer: added metabolic alkalosis
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.
Anion gap
AG = 143 − (97 + 18) = 28
Delta ratio
(28 − 12)/(24 − 18) = 2.667
added metabolic alkalosis
Answer
added metabolic alkalosis
7.Clinical assessment scores
Answer: SI = 0.67
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 = 110/163 = 0.6748 ≈ 0.67
Answer
SI = 0.67
Within or below the usual 0.5–0.7.
8.Clinical assessment scores
Answer: low
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 9/min → 1
SpO₂ 99% → 0
on air → 0
SBP 150 mmHg → 0
HR 76/min → 0
alert (A) → 0
T 36.8 °C → 0
Total and red scores
NEWS2 = 1 + 0 + 0 + 0 + 0 + 0 + 0 = 1
No parameter scores 3.
Risk group
low
Answer
low
9.Enteral & parenteral nutrition calculations
Answer: ΔP = 41.6 g/day
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.
Protein needed
1.2·80 = 96 g/day
Protein from the feed
55·18 = 990 mL = 0.99 L
0.99·55 = 54.45 g/day
Shortfall
ΔP = 96 − 54.45 = 41.55 ≈ 41.6 g/day
Answer
ΔP = 41.6 g/day
10.Enteral & parenteral nutrition calculations
Answer: NPC : N = 116
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: 15·2400/100 = 360 g
amino acids: 5·2400/100 = 120 g
Kilocalories per component
dextrose: 360·3.4 = 1224 kcal
amino acids: 120·4 = 480 kcal
lipid: 500·2 = 1000 kcal
Non-protein kcal and nitrogen
NPC = 1224 + 1000 = 2224 kcal
N = 120/6.25 = 19.2 g
Ratio
NPC : N = 2224/19.2 = 115.8 ≈ 116 : 1
Answer
NPC : N = 116
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
11.ECG rhythm strip interpretation
Answer: pause = 1.6 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
40 small boxes from R to R across the pause
Convert
pause = 40 × 0.04 s = 1.6 s
Compare with P–P
1.60 ÷ 0.92 ≈ 1.7 P–P cycles, not a whole number
Answer
pause = 1.6 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: asystole
Ventricular rhythms: ventricular tachycardia is a run of three or more wide (0.12 s or more) complexes in a row at more than 100/min, usually 150–250/min, regular, without related P waves. Ventricular fibrillation is a chaotic, irregular waveform with no identifiable P waves, QRS complexes or T waves and no countable rate. Asystole is an almost flat line with no ventricular activity; a flat line is always confirmed by checking the patient, the leads and the gain and a second lead. In resuscitation guidelines VF and pulseless VT are the shockable rhythms and asystole is not.
Five steps
1. Rate: no countable ventricular rate.
2. Rhythm: none; an almost flat line.
3. P waves: none identifiable.
4. PR interval: not measurable.
5. QRS: no QRS complexes.
Interpretation
asystole
Answer
asystole
A flat line is always checked: look at the patient, the leads and the gain, and view a second lead, because a loose electrode or fine VF can look like asystole.
13.Prioritization & delegation
Answer: C · Rising systolic pressure, slow pulse and irregular breathing
Why this is the answer
Cushing’s triad (high systolic pressure with a widening pulse pressure, bradycardia and irregular respirations) is a late sign of raised intracranial pressure and needs urgent escalation.
Answer
C · Rising systolic pressure, slow pulse and irregular breathing
14.Prioritization & delegation
Answer: C · Head of the bed at about 30 degrees with the neck straight
Why this is the answer
Raising the head to about 30 degrees and keeping the neck in line helps venous drainage and lowers intracranial pressure. Head-down positions and neck bending or turning can raise it.
Answer
C · Head of the bed at about 30 degrees with the neck straight
15.Infection control & patient safety
Answer: C · At the bedside, in front of the patient, right after collection
Why this is the answer
Labeling tubes at the bedside, using two patient identifiers and in the patient’s presence, prevents wrong-patient specimens. Pre-labeled or later-labeled tubes are easily mixed up.
Answer
C · At the bedside, in front of the patient, right after collection
16.Infection control & patient safety
Answer: B · Close the doors to patient rooms, stay on the unit and wait for instructions
Why this is the answer
Closing doors limits the spread of smoke and fire. Staff follow the fire plan, keep corridors clear and prepare for evacuation, but do not evacuate until directed or the fire is in their area.
Answer
B · Close the doors to patient rooms, stay on the unit and wait for instructions
17.Lab values & electrolytes
Answer: B · Urine output and kidney function
Why this is the answer
The kidneys excrete potassium, so poor urine output or kidney failure can lead to dangerous hyperkalemia during replacement. IV potassium is always diluted and given by infusion pump, never as an IV push.Checked against:High potassium level · MedlinePlus (NIH) (2025)
Answer
B · Urine output and kidney function
18.Lab values & electrolytes
Answer: A · Amiodarone has raised the digoxin level
Why this is the answer
Amiodarone reduces digoxin clearance, so the level can rise significantly, and the digoxin dose is often reduced when amiodarone is started. Nausea and visual changes are classic signs of digoxin toxicity.