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
When cleaning a surgical incision, in which direction should the nurse clean?
AIn circles from the outside in, reusing the swab
BBack and forth along the incision with the same swab
CFrom the incision outwards, using a new swab for each stroke
DFrom the surrounding skin towards the incision with one swab
2.Nursing fundamentalsHard
What should the nurse check before giving digoxin?
AThe blood glucose level
BThe apical pulse for a full minute
CThe radial pulse for 15 seconds
DThe temperature
3.Clinical nursingMedium
The WHO analgesic ladder recommends:
AMoving from non-opioids to weak and then strong opioids as pain increases
BUsing only non-drug methods for cancer pain
CStarting all patients on strong opioids
DGiving analgesia only when pain becomes severe
4.Clinical nursingHard
A patient's hypoglycaemia was caused by a sulfonylurea such as gliclazide or glipizide. Why might they need monitoring for longer than usual?
ASulfonylureas act for a long time, so hypoglycaemia can recur
BThe drug makes glucose tablets and drinks ineffective
CThe drug causes rebound hyperglycaemia later the same day
DSulfonylureas only work at night
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 77 mmHg (10.3 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 a respiratory acidosis: pH 7.29, PaCO₂ 84 mmHg (11.2 kPa), HCO₃⁻ 39 mmol/L. Use the rules ‘HCO₃⁻ rises 1 mmol/L per 10 mmHg (acute) or 3.5 mmol/L per 10 mmHg (chronic)’ to classify it. Click your answer.
pH 7.29PaCO₂ 84 mmHg (11.2 kPa)HCO₃⁻ 39 mmol/L
1acute
2chronic
3acute on chronic
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). A patient has a pulse of 89/min and a blood pressure of 84/50 mmHg. Find the shock index SI = HR/SBP. Round to two decimal places.
HR 89/minBP 84/50 mmHg
SI =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). The team aims for a mean arterial pressure of at least 60 mmHg. A patient’s systolic pressure is 98 mmHg. Using MAP = (SBP + 2·DBP)/3, what is the lowest diastolic pressure DBP that still gives a MAP of 60 mmHg?
Practice exercise (made-up values, not clinical guidance). A 52 kg patient needs 1.8 g of protein per kg a day. The tube feed contains 55 g of protein per litre and runs at 70 mL/h for 16 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 20% dextrose and 4.25% amino acids, plus 250 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein energy NPC in kcal per day. Round to the nearest whole number.
2400 mLdextrose 20%amino acids 4.25%lipid 250 mL · 1.1 kcal/mL
NPC = 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 patient has a pacemaker. Interpret the 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
1paced rhythm, failure to capture
2second-degree AV block type II
3third-degree (complete) AV block
4idioventricular rhythm
13.Prioritization & delegationMedium
Using the Emergency Severity Index, which level fits a 70-year-old with chest pressure that suggests a heart attack, but normal vital signs?
ALevel 2
BLevel 1
CLevel 5
DLevel 4
14.Prioritization & delegationHard
Two weeks after birth, a mother says she hears voices telling her the baby is evil. What is the priority?
ALeave her alone with the baby to bond
BKeep the mother and baby safe and arrange urgent psychiatric care
CReassure her that this is normal “baby blues”
DAdvise more sleep and book a routine follow-up visit for next month
15.Infection control & patient safetyMedium
Sputum specimens are ordered to look for acid-fast bacilli (TB). How are they usually collected?
AOne saliva sample collected at any convenient time of day
BOne specimen of sputum collected straight after the evening meal, when coughing is easiest
CThree deep-cough specimens collected 8 to 24 hours apart, at least one early in the morning
DThree specimens collected after an antiseptic mouthwash
16.Infection control & patient safetyHard
A nurse teaches the daughter of a patient with moderate Alzheimer’s disease about home safety. Which statement shows a need for further teaching?
A“She wears an ID bracelet in case she gets lost.”
B“I keep her medicines locked away and give each dose to her myself.”
C“We put locks high up on the outside doors.”
D“I let Mom cook alone on the gas stove because she enjoys it.”
17.Lab values & electrolytesMedium
Which blood collection practice helps prevent hemolysis of the sample?
AGently inverting the tubes instead of shaking them
BUsing the smallest needle available for every patient
CLeaving the tourniquet on for at least 3 minutes
DForcing blood quickly through a needle into the tube
18.Lab values & electrolytesHard
A lithium level of 1.0 mEq/L was drawn 2 hours after the patient’s morning dose, and the prescriber plans to raise the dose. What should the nurse point out?
ALithium levels can be drawn at any time of day without affecting the result
BThe level is toxic, so lithium should be stopped for good
CThe level is too low, so a large increase is clearly safe
DThe sample was taken too soon after the dose, so it is not a valid level
3Solutions
1.Nursing fundamentals
Answer: C · From the incision outwards, using a new swab for each stroke
Why this is the answer
The incision is the cleanest area, so cleaning moves from it outwards. Using a fresh swab each time avoids bringing skin bacteria back into the wound.
Answer
C · From the incision outwards, using a new swab for each stroke
2.Nursing fundamentals
Answer: B · The apical pulse for a full minute
Why this is the answer
Digoxin slows the heart rate and can cause dangerous bradycardia and arrhythmias in toxicity. The apical pulse is counted for a full minute, and a low or irregular rate is reported before giving it.
Answer
B · The apical pulse for a full minute
3.Clinical nursing
Answer: A · Moving from non-opioids to weak and then strong opioids as pain increases
Why this is the answer
The ladder moves from non-opioids (such as paracetamol) to weak opioids and then strong opioids, with adjuvants at any step. Regular dosing is preferred for persistent pain.
Answer
A · Moving from non-opioids to weak and then strong opioids as pain increases
4.Clinical nursing
Answer: A · Sulfonylureas act for a long time, so hypoglycaemia can recur
Why this is the answer
Sulfonylureas stimulate insulin release and have a long duration of action. Hypoglycaemia can be prolonged or recur, so glucose is monitored closely after treatment.
Answer
A · Sulfonylureas act for a long time, so hypoglycaemia can recur
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 27.7 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
|77 − 40| = 37 mmHg → 3.7 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 1·3.7 = 27.7 mmol/L
Answer
HCO₃⁻ = 27.7 mmol/L
6.Arterial blood gas interpretation
Answer: chronic
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 HCO₃⁻
acute: 24 + 1·4.4 = 28.4 mmol/L
chronic: 24 + 3.5·4.4 = 39.4 mmol/L
Compare
measured: 39 mmol/L → chronic
Answer
chronic
7.Clinical assessment scores
Answer: SI = 1.06
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 = 89/84 = 1.06
Answer
SI = 1.06
1 or more: a warning sign of shock in this practice case.
8.Clinical assessment scores
Answer: DBP = 41 mmHg
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.
Rearrange
DBP = (3·MAP − SBP)/2
Substitute
DBP = (3·60 − 98)/2 = 82/2 = 41 mmHg
Answer
DBP = 41 mmHg
9.Enteral & parenteral nutrition calculations
Answer: ΔP = 32 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
1.8·52 = 93.6 g/day
Protein from the feed
70·16 = 1120 mL = 1.12 L
1.12·55 = 61.6 g/day
Shortfall
ΔP = 93.6 − 61.6 = 32 g/day
Answer
ΔP = 32 g/day
10.Enteral & parenteral nutrition calculations
Answer: NPC = 1907 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: 20·2400/100 = 480 g
amino acids: 4.25·2400/100 = 102 g
Kilocalories per component
dextrose: 480·3.4 = 1632 kcal
amino acids: 102·4 = 408 kcal
lipid: 250·1.1 = 275 kcal
Non-protein energy
NPC = 1632 + 275 = 1907 kcal/day
Answer
NPC = 1907 kcal/day
11.ECG rhythm strip interpretation
Answer: pause = 2.2 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
55 small boxes from R to R across the pause
Convert
pause = 55 × 0.04 s = 2.2 s
Compare with P–P
2.20 ÷ 0.96 ≈ 2.3 P–P cycles, not a whole number
Answer
pause = 2.2 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: paced rhythm, failure to capture
Paced rhythms: a pacemaker impulse shows as a narrow vertical pacing spike. After a ventricular spike the QRS is wide (0.12 s or more), because the impulse spreads from the lead through the muscle instead of the conduction system; with right-ventricular pacing it is often mostly negative in lead II. A spike before each P wave means atrial pacing, and a dual-chamber (AV) pacemaker shows an atrial spike and a P wave, then, after the programmed AV delay, a ventricular spike and a wide QRS. Capture means every spike is followed by a depolarisation. Failure to capture is a spike without a P wave or QRS after it; failure to sense (spikes that ignore the patient’s own beats) and failure to pace (no spike when one is due) are the other classic malfunctions.
Five steps
1. Rate: 4 QRS complexes in 6 s, × 10 = 40 per minute.
2. Rhythm: the pacing spikes are regular (every 1.00 s), but the R–R is not, because a QRS is missing after some spikes.
3. P waves: none visible.
4. PR interval: not measurable.
5. QRS: 0.16 s and wide after the captured spikes; 2 spikes are not followed by a QRS (no capture).
Interpretation
paced rhythm, failure to capture
Answer
paced rhythm, failure to capture
Failure to capture: the pacemaker fires but the heart does not respond. Textbooks treat it as urgent to report, because the patient may depend on the pacemaker.
13.Prioritization & delegation
Answer: A · Level 2
Why this is the answer
Possible acute coronary syndrome is a high-risk situation, so the patient is ESI level 2 and should be seen very soon. Level 1 is kept for patients who need an immediate life-saving intervention.
Answer
A · Level 2
14.Prioritization & delegation
Answer: B · Keep the mother and baby safe and arrange urgent psychiatric care
Why this is the answer
Hallucinations and delusions after birth suggest postpartum psychosis, a psychiatric emergency with risk to mother and baby. Safety and urgent specialist care are the priorities.
Answer
B · Keep the mother and baby safe and arrange urgent psychiatric care
15.Infection control & patient safety
Answer: C · Three deep-cough specimens collected 8 to 24 hours apart, at least one early in the morning
Why this is the answer
Several deep-cough sputum samples improve the chance of finding acid-fast bacilli, and early-morning samples contain the most secretions. Saliva is not sputum, and antiseptic mouthwash can affect the result.
Answer
C · Three deep-cough specimens collected 8 to 24 hours apart, at least one early in the morning
16.Infection control & patient safety
Answer: D · “I let Mom cook alone on the gas stove because she enjoys it.”
Why this is the answer
People with moderate dementia may forget a lit stove, causing fires or burns. Cooking should be supervised, or stove knobs removed or controls disabled. The other statements show good safety planning.
Answer
D · “I let Mom cook alone on the gas stove because she enjoys it.”
17.Lab values & electrolytes
Answer: A · Gently inverting the tubes instead of shaking them
Why this is the answer
Hemolysis falsely raises potassium and affects other results. It is reduced by gentle inversion of tubes, avoiding very small needles, avoiding strong suction or forcing blood through a needle, and keeping tourniquet time short.
Answer
A · Gently inverting the tubes instead of shaking them
18.Lab values & electrolytes
Answer: D · The sample was taken too soon after the dose, so it is not a valid level
Why this is the answer
Lithium levels are standardized at about 12 hours after the last dose, usually just before the morning dose. A sample 2 hours after a dose catches the absorption peak and is not comparable with the target range, so the dose should not be changed on it.
Answer
D · The sample was taken too soon after the dose, so it is not a valid level