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 is at high risk of falling. Which measure is most appropriate?
AKeep the bed low, the call bell within reach and non-slip footwear on
BGive a sedative at night
CRestrict the patient to bed without assessment
DRaise all bed rails routinely and keep the patient in bed until reviewed
2.Nursing fundamentalsHard
A confused patient repeatedly tries to climb over raised bed rails. What is the safest approach?
AGive a sedative without a medical review
BTie the patient's wrists to the bed
CReassess and consider alternatives such as a low bed and closer observation
DRaise the rails higher and leave the patient alone in a quiet room so they can settle
3.Clinical nursingMedium
Which adverse effects should be monitored for in a patient receiving IV gentamicin?
AConstipation and urinary retention
BHair loss and weight gain
CKidney damage and hearing loss
DHyperglycaemia and tremor
4.Clinical nursingHard
A nurse teaches a patient with heart failure about self-care. Which statement shows a need for further teaching?
A"I will weigh myself each morning after passing urine."
B"I will report it if I need more pillows to sleep."
C"I only need to weigh myself once a month."
D"I will take my water tablet in the morning."
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 22 mmHg (2.9 kPa). Use the rule that in chronic respiratory alkalosis HCO₃⁻ falls by 5 mmol/L for every 10 mmHg that PaCO₂ is below 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
A practice gas shows a metabolic alkalosis with HCO₃⁻ 33 mmol/L. Use expected PaCO₂ = 0.7·HCO₃⁻ + 21 to find the expected PaCO₂.
HCO₃⁻ 33 mmol/L
PaCO₂ = mmHg
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). A practice patient after a head injury opens the eyes when spoken to, talks in sentences but is confused and shows as the best motor response: withdraws the limb from pressure (normal flexion). 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). A practice patient is assessed with the Morse fall scale: history of falling in the last 3 months: no; secondary diagnosis: yes; ambulatory aid: none, bed rest or nurse assists; IV therapy or saline lock: no; gait: impaired; mental status: knows own limits. Using the cut-offs 0–24 low, 25–44 moderate and 45 or more high, click the fall-risk level.
Practice exercise (made-up values, not clinical guidance). A woman is 173 cm tall and weighs 59 kg. Find the actual weight as a percentage of the ideal body weight, %IBW, using the Devine formula (1 in = 2.54 cm). Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). Over 24 hours a patient receives 2000 mL of parenteral nutrition with final concentrations of 17.5% dextrose and 5% amino acids, plus 500 mL of 10% lipid emulsion (1.1 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
2000 mLdextrose 17.5%amino acids 5%lipid 500 mL · 1.1 kcal/mL
NPC : N =
11.ECG rhythm strip interpretationMedium
Measure the QT interval and the R–R interval on this regular lead II strip, then calculate the rate-corrected QTc with Fridericia’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
Interpret this lead II strip. Which interpretation can you defend from this single 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
12:1 AV block (type undetermined)
2second-degree AV block type II
3first-degree AV block
4second-degree AV block type I (Wenckebach)
13.Prioritization & delegationMedium
Which action helps prevent a catheter-associated urinary tract infection?
AKeeping the drainage bag below the level of the bladder
BLeaving the catheter in place longer than needed
CDisconnecting the bag every shift to empty it
DRaising the drainage bag above the bladder when walking
14.Prioritization & delegationHard
A nurse teaches a patient to inject enoxaparin at home. Which statement shows a need for further teaching?
A“I will change the injection site each time.”
B“I will rub the area after the injection to help it absorb.”
C“I will inject into the fat of my abdomen, away from the navel.”
D“I will tell my doctor if I notice unusual bruising or bleeding.”
15.Infection control & patient safetyMedium
A nurse finds an unlabeled syringe of clear fluid on the medication counter. What should the nurse do?
ALabel it with the most likely drug name
BGive it to the patient whose medication is due
CAsk nearby staff and use it if someone recognizes it
DDiscard it, because its contents cannot be confirmed
16.Infection control & patient safetyHard
Only one airborne infection isolation room (negative pressure) is free. Which newly admitted patient should be placed in it?
AA patient with suspected active pulmonary tuberculosis
BA patient with confirmed seasonal influenza and a cough
CA patient with an MRSA wound infection
DA patient with C. difficile diarrhea
17.Lab values & electrolytesMedium
A patient takes valproate (valproic acid) for epilepsy. Which tests are monitored regularly?
ALiver function tests and platelet count
BTroponin and B-type natriuretic peptide
CThyroid function and serum calcium
DSerum lithium and urine specific gravity
18.Lab values & electrolytesHard
A patient with jaundice and nausea has a positive IgM antibody to hepatitis A virus (IgM anti-HAV). What does this show?
AA current or recent hepatitis A infection
BChronic hepatitis A lasting many years
CImmunity from hepatitis A vaccine long ago
DPast hepatitis B infection that has cleared
3Solutions
1.Nursing fundamentals
Answer: A · Keep the bed low, the call bell within reach and non-slip footwear on
Why this is the answer
Standard fall prevention includes a low bed, call bell and personal items within reach, good lighting, footwear and regular checks. Bed rails and sedation need an individual assessment.
Answer
A · Keep the bed low, the call bell within reach and non-slip footwear on
2.Nursing fundamentals
Answer: C · Reassess and consider alternatives such as a low bed and closer observation
Why this is the answer
For a patient climbing over them, bed rails can increase injury risk. Using the least restrictive option, such as a low bed, a floor mat and closer observation, while treating the cause of confusion, is safer.
Answer
C · Reassess and consider alternatives such as a low bed and closer observation
3.Clinical nursing
Answer: C · Kidney damage and hearing loss
Why this is the answer
Gentamicin is nephrotoxic and ototoxic. Blood levels and renal function are monitored, and any tinnitus, dizziness or hearing change is reported.
Answer
C · Kidney damage and hearing loss
4.Clinical nursing
Answer: C · "I only need to weigh myself once a month."
Why this is the answer
Daily weights at the same time with the same scales detect fluid retention early. A rapid gain, worsening breathlessness or needing more pillows should be reported.
Answer
C · "I only need to weigh myself once a month."
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 15 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
|22 − 40| = 18 mmHg → 1.8 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 − 5·1.8 = 15 mmol/L
Answer
HCO₃⁻ = 15 mmol/L
6.Arterial blood gas interpretation
Answer: PaCO₂ = 44.1 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
0.7·33 + 21 = 44.1 mmHg
Answer
PaCO₂ = 44.1 mmHg
The rise has a limit: PaCO₂ rarely goes above about 55 mmHg from compensation alone.
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: talks in sentences but is confused → 4
M: withdraws the limb from pressure (normal flexion) → 4
Add
GCS = 3 + 4 + 4 = 11
Severity
GCS 11 → moderate
Answer
moderate
8.Clinical assessment scores
Answer: moderate risk
Morse fall scale: six items. History of falling: no 0, yes 25. Secondary diagnosis: no 0, yes 15. Ambulatory aid: none, bed rest or nurse assistance 0; crutches, cane or walker 15; holding on to furniture 30. IV therapy or saline lock: no 0, yes 20. Gait: normal, bed rest or wheelchair 0; weak 10; impaired 20. Mental status: knows own limits 0; overestimates or forgets limits 15. The total runs from 0 to 125. Risk cut-offs differ between hospitals; a common set is 0–24 low, 25–44 moderate and 45 or more high.
Score each item
history of falling in the last 3 months: no → 0
secondary diagnosis: yes → 15
ambulatory aid: none, bed rest or nurse assists → 0
IV therapy or saline lock: no → 0
gait: impaired → 20
mental status: knows own limits → 0
Add
Morse total = 0 + 15 + 0 + 0 + 20 + 0 = 35
Risk level
35 → moderate risk
Answer
moderate risk
9.Enteral & parenteral nutrition calculations
Answer: %IBW = 92 %
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.
Ideal body weight (Devine)
173 cm/2.54 = 68.11 in
IBW = 45.5 + 2.3·(68.11 − 60) = 64.15 kg
Percentage of ideal body weight
%IBW = 59/64.15·100 = 91.97 ≈ 92%
Answer
%IBW = 92%
10.Enteral & parenteral nutrition calculations
Answer: NPC : N = 109
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: 17.5·2000/100 = 350 g
amino acids: 5·2000/100 = 100 g
Kilocalories per component
dextrose: 350·3.4 = 1190 kcal
amino acids: 100·4 = 400 kcal
lipid: 500·1.1 = 550 kcal
Non-protein kcal and nitrogen
NPC = 1190 + 550 = 1740 kcal
N = 100/6.25 = 16 g
Ratio
NPC : N = 1740/16 = 108.8 ≈ 109 : 1
Answer
NPC : N = 109
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
11.ECG rhythm strip interpretation
Answer: QTc = 0.494 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 = 12 × 0.04 = 0.48 s
RR = 23 × 0.04 = 0.92 s
Fridericia’s formula
QTc = 0.48/∛0.92 = 0.48/0.9726 = 0.494 s
Answer
QTc = 0.494 s
Above the usual limits for both men (about 0.45 s) and women (about 0.46 s): prolonged. (494 ms)
12.ECG rhythm strip interpretation
Answer: 2:1 AV block (type undetermined)
2:1 AV block: with two P waves for every QRS, no two conducted P waves follow each other, so you cannot see whether the PR would lengthen (type I) or stay constant (type II) before a non-conducted P wave. From one strip it is called a 2:1 AV block; a longer strip or a change in the conduction ratio decides the type. A narrow QRS makes type I more likely and a wide QRS type II, but neither proves it.
Five steps
1. Rate: R–R = 38 small boxes, 1500 ÷ 38 ≈ 39 per minute.
2. Rhythm: regular, every R–R is 1.52 s.
3. P waves: upright and regular (P–P 0.76 s, 79 per minute), two for every QRS.
4. PR interval: constant at 0.18 s in the conducted beats.
5. QRS: 0.06 s, narrow (below 0.12 s).
Why the type stays open
Every second P wave is not conducted, so no two conducted beats follow each other and a lengthening PR could never show.
2:1 AV block (type undetermined)
Answer
2:1 AV block (type undetermined)
A narrow QRS makes type I more likely and a wide QRS type II, but only a longer strip or a change in the conduction ratio decides.
13.Prioritization & delegation
Answer: A · Keeping the drainage bag below the level of the bladder
Why this is the answer
Keeping the bag below the bladder prevents backflow, and the closed system is not broken. Catheters are removed as soon as they are no longer needed.
Answer
A · Keeping the drainage bag below the level of the bladder
14.Prioritization & delegation
Answer: B · “I will rub the area after the injection to help it absorb.”
Why this is the answer
Rubbing the site after a low-molecular-weight heparin injection increases bruising. The abdomen away from the navel, rotating sites and reporting bleeding are correct.
Answer
B · “I will rub the area after the injection to help it absorb.”
15.Infection control & patient safety
Answer: D · Discard it, because its contents cannot be confirmed
Why this is the answer
An unlabeled syringe could contain any drug or dose. It is discarded, and syringes are labeled straight away whenever they are not given immediately.
Answer
D · Discard it, because its contents cannot be confirmed
16.Infection control & patient safety
Answer: A · A patient with suspected active pulmonary tuberculosis
Why this is the answer
Tuberculosis needs airborne precautions in a negative-pressure room. Influenza needs droplet precautions and MRSA and C. difficile need contact precautions, which can be given in an ordinary single room.
Answer
A · A patient with suspected active pulmonary tuberculosis
17.Lab values & electrolytes
Answer: A · Liver function tests and platelet count
Why this is the answer
Valproate can cause liver toxicity and thrombocytopenia, so liver tests and the platelet count are monitored. It can also raise ammonia; confusion or vomiting should prompt an ammonia level.Checked against:Valproic Acid · StatPearls (NCBI Bookshelf) (2024)
Answer
A · Liver function tests and platelet count
18.Lab values & electrolytes
Answer: A · A current or recent hepatitis A infection
Why this is the answer
IgM antibodies appear early, so IgM anti-HAV indicates acute hepatitis A. IgG anti-HAV alone shows past infection or vaccination and lifelong immunity. Hepatitis A does not become chronic and spreads by the fecal-oral route, so hand hygiene is essential.Checked against:Hepatitis A · MedlinePlus (NIH) (2025)