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
How can nurses help patients sleep better on a hospital ward at night?
AGroup care and observations so patients are disturbed less often
BKeep the main lights on so staff can see clearly
CDo routine tasks such as bed changes at midnight while it is quiet
DGive every patient a sleeping tablet
2.Nursing fundamentalsHard
A patient with capacity refuses a prescribed treatment. What should the nurse do?
ARespect the refusal, make sure they understand the consequences, inform the team and document it
BAsk a relative to consent instead
CHide the medicine in the patient's food
DGive the treatment anyway, because it was prescribed and the doctor has decided it is in their best interests
3.Clinical nursingMedium
Which side effects are common after high doses of salbutamol (albuterol)?
AHair loss and weight gain
BBradycardia and drowsiness
CConstipation and urinary retention
DTremor and a fast heart rate
4.Clinical nursingHard
Shortly after starting a transfusion, a patient becomes breathless, wheezy and hypotensive with facial swelling. What should the nurse do first?
ASlow the transfusion rate and recheck the observations in an hour
BStop the transfusion, keep IV access and call for urgent help
CGive paracetamol and an antihistamine and continue the transfusion
DFinish the unit quickly so the exposure time is as short as possible
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 128 mmol/L, glucose 23.8 mmol/L and urea 21.4 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 128 mmol/Lglucose 23.8 mmol/Lurea 21.4 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
Practice values: Na⁺ 141, Cl⁻ 104, HCO₃⁻ 17 mmol/L and albumin 20 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).
Practice exercise (made-up values, not clinical guidance). A practice patient after a head injury opens the eyes when spoken to, says inappropriate, random words and shows as the best motor response: abnormal flexion of the arms (decorticate posture). Work out the GCS and classify the head injury by it. Click your answer.
1mild
2moderate
3severe
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). The team aims for a mean arterial pressure of at least 65 mmHg. A patient’s systolic pressure is 117 mmHg. Using MAP = (SBP + 2·DBP)/3, what is the lowest diastolic pressure DBP that still gives a MAP of 65 mmHg?
Practice exercise (made-up values, not clinical guidance). Use the Devine formula to find the ideal body weight IBW of a man who is 164 cm tall (1 in = 2.54 cm). Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A critically ill woman is 177 cm tall and weighs 137 kg. The practice protocol gives 2 g of protein per kg of ideal body weight (Devine) per day if the BMI is 30 to under 40 kg/m², and 2.5 g/kg of ideal body weight per day if the BMI is 40 kg/m² or more. Find the protein goal P in g/day. Round to the nearest whole number.
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 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
1third-degree (complete) AV block
2sinus rhythm with wide QRS
3ventricular paced rhythm
4idioventricular rhythm
13.Prioritization & delegationMedium
A nurse teaches a patient with COPD pursed-lip breathing. Which statement shows a need for further teaching?
A“I will breathe in through my mouth and out quickly through my nose.”
B“I will make my breath out about twice as long as my breath in.”
C“I will breathe in slowly through my nose.”
D“I will breathe out slowly through pursed lips.”
14.Prioritization & delegationHard
Which patient’s finding is the most urgent?
AA patient on warfarin with an INR of 2.5 who is due for the usual evening dose
BA patient whose platelet count result is pending
CA patient on a heparin infusion who has new confusion and a severe headache
DA patient after knee surgery with a small bruise at an injection site
15.Infection control & patient safetyMedium
A nurse cleans an IV pump with a disinfectant wipe. What must happen for the disinfectant to work?
AThe wipe is used on many pumps to save product
BThe surface is wiped once lightly without pressure
CThe surface is dried with a clean towel right after wiping
DThe surface stays wet for the contact time on the product label
16.Infection control & patient safetyHard
A patient who speaks little English is being discharged with new medications. The patient’s 12-year-old child offers to interpret. What should the nurse do?
AUse a professional medical interpreter
BGive written instructions in English only
CUse simple English and many hand gestures
DLet the child interpret, because the family prefers it
17.Lab values & electrolytesMedium
A patient with a potassium of 2.8 mEq/L has potassium chloride prescribed IV. Which statement about giving it is correct?
AIt is added to the IV bag without mixing, so it stays at the bottom
BIt may be given as a slow IV push over one minute if the level is very low
CIt is always diluted and given by infusion pump, never as an IV push
DIt is given as an undiluted bolus into a large vein to avoid irritation
18.Lab values & electrolytesHard
A patient on a stable dose of levothyroxine now has a TSH of 9.8 mIU/L. She recently started taking her calcium and iron supplements with her morning levothyroxine. What is the most likely explanation?
AThe supplements are reducing levothyroxine absorption
BThe result is normal for a person on levothyroxine therapy
CThe TSH is low, showing that the dose is now too high
DThe supplements are causing an overactive thyroid gland
3Solutions
1.Nursing fundamentals
Answer: A · Group care and observations so patients are disturbed less often
Why this is the answer
Clustering care, dimming lights, reducing noise and offering eye masks or earplugs improve sleep. Sedatives carry risks and are not routine.
Answer
A · Group care and observations so patients are disturbed less often
2.Nursing fundamentals
Answer: A · Respect the refusal, make sure they understand the consequences, inform the team and document it
Why this is the answer
An adult with capacity may refuse treatment. The nurse should explore the reasons, give information, inform the prescriber and document. Covert administration without proper legal process is not acceptable.
Answer
A · Respect the refusal, make sure they understand the consequences, inform the team and document it
3.Clinical nursing
Answer: D · Tremor and a fast heart rate
Why this is the answer
Salbutamol is a beta2-agonist and can cause tremor, tachycardia and palpitations. High doses can also lower serum potassium.
Answer
D · Tremor and a fast heart rate
4.Clinical nursing
Answer: B · Stop the transfusion, keep IV access and call for urgent help
Why this is the answer
Severe transfusion reactions, including anaphylaxis, require immediately stopping the transfusion, keeping venous access, following the ABCDE approach and treating anaphylaxis with IM adrenaline.
Answer
B · Stop the transfusion, keep IV access and call for urgent help
5.Arterial blood gas interpretation
Answer: Osm = 301 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 = 2·128 + 23.8 + 21.4 = 301.2 ≈ 301 mOsm/kg
Answer
Osm = 301 mOsm/kg
6.Arterial blood gas interpretation
Answer: AGc = 25 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.
Anion gap
AG = 141 − (104 + 17) = 20
Correction for albumin
20 + 0.25·(40 − 20) = 25 mmol/L
Answer
AGc = 25 mmol/L
Above about 12 after correction: a high anion gap.
7.Clinical assessment scores
Answer: moderate
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.
Score each area
E: opens the eyes when spoken to → 3
V: says inappropriate, random words → 3
M: abnormal flexion of the arms (decorticate posture) → 3
Add
GCS = 3 + 3 + 3 = 9
Severity
GCS 9 → moderate
Answer
moderate
8.Clinical assessment scores
Answer: DBP = 39 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 = (3·65 − 117)/2 = 78/2 = 39 mmHg
Answer
DBP = 39 mmHg
9.Enteral & parenteral nutrition calculations
Answer: IBW = 60.5 kg
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.
Height in inches
164 cm/2.54 = 64.57 in
Ideal body weight (Devine)
IBW = 50 + 2.3·(64.57 − 60) = 60.5 kg
Answer
IBW = 60.5 kg
10.Enteral & parenteral nutrition calculations
Answer: P = 169 g/day
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. Obesity in critical illness (ASPEN/SCCM 2016): BMI = weight/height² (kg/m²). The protein goal is 2 g/kg of ideal body weight per day for BMI 30–40 and up to 2.5 g/kg of ideal body weight per day for BMI 40 and above. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Body mass index
BMI = 137/1.77² = 43.73 kg/m²
Ideal body weight (Devine)
177 cm/2.54 = 69.69 in
IBW = 45.5 + 2.3·(69.69 − 60) = 67.78 kg
Protein goal
BMI 40 or more: 2.5 g per kg of ideal body weight.
P = 2.5·67.78 = 169.4 ≈ 169 g/day
Answer
P = 169 g/day
11.ECG rhythm strip interpretation
Answer: QTc = 0.387 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 = 7.5 × 0.04 = 0.30 s
RR = 15 × 0.04 = 0.60 s
Bazett’s formula
QTc = 0.30/√0.60 = 0.30/0.7746 = 0.387 s
Answer
QTc = 0.387 s
Within the usual limits (about 0.45 s for men, 0.46 s for women). (387 ms)
12.ECG rhythm strip interpretation
Answer: ventricular paced rhythm
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: R–R = 24 small boxes, 1500 ÷ 24 ≈ 63 per minute.
2. Rhythm: regular, every R–R is 0.96 s.
3. P waves: none visible; a sharp pacing spike comes just before every QRS.
4. PR interval: not measurable.
5. QRS: 0.16 s, wide, and every spike is followed by a QRS (capture).
Interpretation
ventricular paced rhythm
Answer
ventricular paced rhythm
The paced QRS is wide by nature; do not call it a bundle branch block or a ventricular rhythm.
13.Prioritization & delegation
Answer: A · “I will breathe in through my mouth and out quickly through my nose.”
Why this is the answer
Pursed-lip breathing means breathing in through the nose and out slowly through pursed lips, making exhalation longer. This keeps airways open and reduces air trapping.
Answer
A · “I will breathe in through my mouth and out quickly through my nose.”
14.Prioritization & delegation
Answer: C · A patient on a heparin infusion who has new confusion and a severe headache
Why this is the answer
New confusion and a severe headache in an anticoagulated patient may mean an intracranial bleed. An INR of 2.5 is within the common therapeutic range of 2 to 3, and a small injection-site bruise is common.
Answer
C · A patient on a heparin infusion who has new confusion and a severe headache
15.Infection control & patient safety
Answer: D · The surface stays wet for the contact time on the product label
Why this is the answer
Each disinfectant has a contact (dwell) time during which the surface must stay visibly wet. Drying it early or spreading one wipe over many items reduces its effect.
Answer
D · The surface stays wet for the contact time on the product label
16.Infection control & patient safety
Answer: A · Use a professional medical interpreter
Why this is the answer
Professional medical interpreters reduce errors and protect privacy. Children and other family members may translate wrongly, leave things out or be placed in a difficult position.
Answer
A · Use a professional medical interpreter
17.Lab values & electrolytes
Answer: C · It is always diluted and given by infusion pump, never as an IV push
Why this is the answer
Concentrated potassium chloride given as an IV push can cause fatal cardiac arrest, so it is never pushed. It is diluted, mixed well and given by infusion pump at a rate set by protocol, often with cardiac monitoring at higher rates.
Answer
C · It is always diluted and given by infusion pump, never as an IV push
18.Lab values & electrolytes
Answer: A · The supplements are reducing levothyroxine absorption
Why this is the answer
Calcium, iron and antacids bind levothyroxine in the gut and reduce absorption, so the TSH rises. Levothyroxine is taken on an empty stomach, usually 30–60 minutes before breakfast, separated from these supplements by about 4 hours.
Answer
A · The supplements are reducing levothyroxine absorption