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 measures help prevent constipation in hospital patients?
AHolding in the urge to open the bowels
BAvoiding fruit and vegetables
CAdequate fluids, dietary fibre and mobility
DLimiting fluids and staying in bed to rest the bowel
2.Nursing fundamentalsHard
How should a urine sample be taken from a patient with a urinary catheter?
ABy disconnecting the catheter from the bag
BFrom the sampling port, using aseptic technique
CFrom the drainage bag tap
DBy removing the catheter and collecting the next void
3.Clinical nursingMedium
Which tool is commonly used at the bedside to screen for delirium?
AThe Glasgow-Blatchford score
BThe Braden scale
CThe Malnutrition Universal Screening Tool
DThe Confusion Assessment Method (CAM)
4.Clinical nursingHard
A hypotensive postoperative patient is given a fluid bolus. Which findings suggest a good response?
AThe capillary refill time becomes longer
BThe respiratory rate rises and new lung crackles appear
CThe heart rate rises further and the patient becomes more confused
DThe heart rate falls, blood pressure rises and urine output improves
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 141 mmol/L, glucose 11.2 mmol/L and urea 18.5 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 141 mmol/Lglucose 11.2 mmol/Lurea 18.5 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
A practice gas shows a metabolic acidosis: pH 7.14, PaCO₂ 43 mmHg (5.7 kPa), HCO₃⁻ 14 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.
pH 7.14PaCO₂ 43 mmHg (5.7 kPa)HCO₃⁻ 14 mmol/L
1appropriate compensation
2added respiratory acidosis
3added respiratory alkalosis
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). A practice chart records GCS 11, with E3 and V3. What motor score M was recorded, and which response does it describe? Give the number.
GCS 11E3V3
M =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 16/min, SpO₂ 99% on supplemental oxygen, blood pressure 100/60 mmHg, pulse 70/min, alert, temperature 38.8 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). A 48 kg adult (BMI below 30) needs 25 kcal/kg/day. The tube feed provides 1 kcal/mL and runs by pump for 20 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). A critically ill woman is 170 cm tall and weighs 156 kg. The practice protocol gives 11 kcal/kg of actual body weight per day if the BMI is 30–50 kg/m², and 22 kcal/kg of ideal body weight (Devine) per day if the BMI is above 50 kg/m². Find the energy goal E in kcal/day. Round to the nearest whole number.
Interpret this lead II rhythm strip. 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
1sinus bradycardia
2first-degree AV block
3normal sinus rhythm
4sinus tachycardia
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 I (Wenckebach)
3second-degree AV block type II
4junctional rhythm
13.Prioritization & delegationMedium
A patient with angina is taught to use sublingual nitroglycerin (GTN). Which statement shows a need for further teaching?
A“If the pain has not eased as my action plan says, I will call emergency services.”
B“I will carry the tablets with me when I go out.”
C“I will sit or lie down when I take a tablet.”
D“I will take five tablets one after the other before I call for help.”
14.Prioritization & delegationHard
After a cervical spinal cord injury, a patient has a blood pressure of 80/50 mmHg, a heart rate of 48/min and warm, dry skin. What is most likely?
ACardiac tamponade
BSeptic shock
CHypovolemic shock
DNeurogenic shock
15.Infection control & patient safetyMedium
Why should a child’s weight be recorded only in kilograms?
AScales that show kilograms are always more accurate than those that show pounds
BMixing up pounds and kilograms can lead to large dosing errors
CChildren weigh less, so smaller units are needed
DKilograms are easier for parents to remember
16.Infection control & patient safetyHard
A visitor is receiving an electric shock from a faulty lamp and is still touching it. What should the nurse do first?
AStart chest compressions straight away
BPull the visitor away from the lamp by the arm as quickly as possible
CThrow water over the lamp to stop the current
DSwitch off the power or unplug the lamp without touching the person
17.Lab values & electrolytesMedium
On the first day after major surgery, a patient's white cell count is 12.5 × 10³/µL, with no fever or wound signs. What is the best interpretation?
ADefinite wound infection that needs antibiotics now
BA common stress response to surgery that is monitored
CA sign of leukemia that needs bone marrow testing
DA laboratory error, since surgery lowers white cells
18.Lab values & electrolytesHard
A patient stopped long-term prednisone suddenly a week ago. Now: blood pressure 78/46 mm Hg, sodium 128 mEq/L, potassium 4.6 mEq/L, glucose 58 mg/dL (3.2 mmol/L). Which condition is most likely?
AAcute adrenal insufficiency (adrenal crisis)
BCushing syndrome from steroid excess
CPrimary hyperaldosteronism (Conn syndrome)
DSyndrome of inappropriate ADH (SIADH)
3Solutions
1.Nursing fundamentals
Answer: C · Adequate fluids, dietary fibre and mobility
Why this is the answer
Fluids and fibre soften stools, and activity stimulates gut movement. Privacy and responding to the urge to defecate also help. Opioids and immobility increase the risk.
Answer
C · Adequate fluids, dietary fibre and mobility
2.Nursing fundamentals
Answer: B · From the sampling port, using aseptic technique
Why this is the answer
Samples are taken from the needle-free sampling port after cleaning it. Urine in the bag is stale and contaminated, and breaking the system raises infection risk.
Answer
B · From the sampling port, using aseptic technique
3.Clinical nursing
Answer: D · The Confusion Assessment Method (CAM)
Why this is the answer
The CAM, and similar tools such as the 4AT, check for an acute onset or fluctuating course, inattention and disorganised thinking or altered consciousness. Early detection allows causes to be treated.
Answer
D · The Confusion Assessment Method (CAM)
4.Clinical nursing
Answer: D · The heart rate falls, blood pressure rises and urine output improves
Why this is the answer
After a fluid challenge, a falling heart rate, rising blood pressure, better capillary refill, improving consciousness and urine output suggest fluid responsiveness. New crackles or breathlessness suggest fluid overload.
Answer
D · The heart rate falls, blood pressure rises and urine output improves
5.Arterial blood gas interpretation
Answer: Osm = 312 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 = 2·141 + 11.2 + 18.5 = 311.7 ≈ 312 mOsm/kg
Answer
Osm = 312 mOsm/kg
6.Arterial blood gas interpretation
Answer: added respiratory acidosis
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
1.5·14 + 8 = 29 → 27–31 mmHg
Compare
measured: 43 mmHg → added respiratory acidosis
Answer
added respiratory acidosis
7.Clinical assessment scores
Answer: M = 5
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.
Motor score
M = 11 − 3 − 3 = 5
M5: moves a hand to the site of pressure (localises)
Answer
M = 5
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 16/min → 0
SpO₂ 99% → 0
on oxygen → 2
SBP 100 mmHg → 2
HR 70/min → 0
alert (A) → 0
T 38.8 °C → 1
Total and red scores
NEWS2 = 0 + 0 + 2 + 2 + 0 + 0 + 1 = 5
No 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 = 60 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 = 25·48 = 1200 kcal/day
Daily volume
V = 1200/1 = 1200 mL/day
Pump rate
R = 1200/20 = 60 mL/h
Answer
R = 60 mL/h
10.Enteral & parenteral nutrition calculations
Answer: E = 1352 kcal/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). For BMI 30–50 the energy goal is 11–14 kcal/kg of actual body weight per day; above 50 it is 22–25 kcal/kg of ideal body weight per day. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Body mass index
BMI = 156/1.7² = 53.98 kg/m²
Ideal body weight (Devine)
170 cm/2.54 = 66.93 in
IBW = 45.5 + 2.3·(66.93 − 60) = 61.44 kg
Energy goal
BMI above 50: kcal per kg of ideal body weight.
E = 22·61.44 = 1352 kcal/day
Answer
E = 1352 kcal/day
11.ECG rhythm strip interpretation
Answer: first-degree AV block
Rhythm criteria (lead II): sinus rhythm has an upright P wave before every QRS, a constant PR of 0.12–0.20 s and a narrow QRS: normal sinus rhythm at 60–100/min, sinus bradycardia below 60, sinus tachycardia above 100. Atrial fibrillation: no P waves, a fibrillatory baseline and an irregularly irregular R–R. Atrial flutter: sawtooth flutter waves at about 250–350/min with a fixed conduction ratio such as 2:1 or 4:1. First-degree AV block: sinus rhythm with a constant PR above 0.20 s. Junctional rhythm: narrow QRS at 40–60/min with absent or inverted P waves (PR below 0.12 s, or P after the QRS). A PVC is an early, wide (0.12 s or more), bizarre QRS without a P wave, with the T wave in the opposite direction and usually a full compensatory pause; in bigeminy every second beat is a PVC.
Five steps
1. Rate: R–R = 18 small boxes, 1500 ÷ 18 ≈ 83 per minute.
2. Rhythm: regular, every R–R is 0.72 s.
3. P waves: upright, one before every QRS, all alike.
4. PR interval: 0.34 s, constant, longer than 0.20 s.
5. QRS: 0.08 s, narrow (below 0.12 s).
Interpretation
first-degree AV block
Answer
first-degree AV block
12.ECG rhythm strip interpretation
Answer: third-degree (complete) AV block
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: R–R = 50 small boxes, 1500 ÷ 50 ≈ 30 per minute.
2. Rhythm: R–R regular (2.00 s) and P–P regular (0.84 s), but the two are independent.
3. P waves: upright and regular at 71 per minute, but not linked to the QRS complexes; some hide in a QRS or a T wave.
4. PR interval: varies from beat to beat; there is no fixed relation.
5. QRS: 0.16 s, wide (0.12 s or more).
Interpretation
third-degree (complete) AV block
Answer
third-degree (complete) AV block
Type II and third-degree blocks are the ones that can suddenly progress, so textbooks rank them as more serious than type I.
13.Prioritization & delegation
Answer: D · “I will take five tablets one after the other before I call for help.”
Why this is the answer
Action plans differ slightly: US guidance says to call emergency services if pain is not better 5 minutes after the first dose, while UK guidance allows a second dose after 5 minutes and a 999 call if pain persists 5 minutes later. Taking many doses in a row delays care and can cause severe hypotension.
Answer
D · “I will take five tablets one after the other before I call for help.”
14.Prioritization & delegation
Answer: D · Neurogenic shock
Why this is the answer
Neurogenic shock follows loss of sympathetic tone, causing vasodilation, hypotension and bradycardia with warm skin. Hypovolemic shock usually causes a fast pulse and cool, clammy skin.
Answer
D · Neurogenic shock
15.Infection control & patient safety
Answer: B · Mixing up pounds and kilograms can lead to large dosing errors
Why this is the answer
Pediatric doses are often calculated per kilogram. A weight recorded in pounds but read as kilograms gives a dose more than twice as high, so weight is recorded and used only in kilograms.
Answer
B · Mixing up pounds and kilograms can lead to large dosing errors
16.Infection control & patient safety
Answer: D · Switch off the power or unplug the lamp without touching the person
Why this is the answer
The rescuer must not touch someone still in contact with live current. The power is switched off or the plug pulled first, then the person is assessed and resuscitation is started if needed.
Answer
D · Switch off the power or unplug the lamp without touching the person
17.Lab values & electrolytes
Answer: B · A common stress response to surgery that is monitored
Why this is the answer
A mild leukocytosis is common after surgery because of tissue injury and the stress response. It is monitored along with temperature and wound assessment. A rising count after several days, or fever, suggests infection.Checked against:WBC count · MedlinePlus (NIH) (2025)
Answer
B · A common stress response to surgery that is monitored
18.Lab values & electrolytes
Answer: A · Acute adrenal insufficiency (adrenal crisis)
Why this is the answer
Long-term glucocorticoids suppress the body's own cortisol production; stopping them suddenly can cause adrenal crisis. Lack of cortisol causes hypotension, hyponatremia and hypoglycemia. Aldosterone is usually still made, so potassium is often normal; high potassium suggests primary adrenal failure. Treatment is IV hydrocortisone and fluids as prescribed.