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
Why do nurses often count the respiratory rate while still appearing to take the pulse?
ACounting breaths is only accurate when the wrist is held
BThe pulse and breathing rates are always the same number
CIt is not allowed to tell patients that breathing is measured
DPatients who know their breathing is watched tend to change it
2.Nursing fundamentalsHard
A patient's NEWS2 score suddenly rises from 1 to 7. What is the appropriate response?
ARecheck the observations tomorrow morning
BContinue four-hourly observations
CUrgent or emergency response with immediate senior clinical review
DDocument it, repeat the observations and inform the doctor at the next ward round
3.Clinical nursingMedium
A patient is newly confused, has a respiratory rate of 24/min and a systolic blood pressure of 95 mmHg. What should you suspect first?
ANormal postoperative recovery
BAnxiety
CAlcohol intoxication
DSepsis
4.Clinical nursingHard
Which nursing assessment best helps detect early deterioration in a patient after major surgery?
AAsking the patient only whether they feel well
BChecking the wound only at discharge
CMeasuring temperature once a day
DRegular full sets of observations with an early warning score and trend review
5.Arterial blood gas interpretationMedium
A practice arterial blood gas shows pH 7.31, PaCO₂ 33 mmHg (4.4 kPa) and HCO₃⁻ 16 mmol/L. The primary disorder is metabolic acidosis. How far is it compensated? Click your answer.
pH 7.31PaCO₂ 33 mmHg (4.4 kPa)HCO₃⁻ 16 mmol/L
1uncompensated
2partially compensated
3fully compensated
6.Arterial blood gas interpretationHard
At sea level, a practice gas taken on 40% oxygen shows PaO₂ 74 mmHg (9.9 kPa) and PaCO₂ 31 mmHg (4.1 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 16/min, SpO₂ 97% on supplemental oxygen, blood pressure 142/86 mmHg, pulse 64/min, alert, temperature 38.8 °C. What is the NEWS2 total score?
RR 16SpO₂ 97%O₂SBP 142HR 64AT 38.8 °C
NEWS2 =
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: yes; secondary diagnosis: yes; ambulatory aid: crutches, cane or walker; IV therapy or saline lock: no; gait: weak; mental status: overestimates or forgets 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 77 kg patient has a fluid goal of 30 mL/kg/day and receives all fluid through a feeding tube. The formula is 76% free water and runs at 55 mL/h for 24 hours a day. The rest of the fluid is given as water flushes every 4 hours. What volume V is each flush? Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). A critically ill man is 183 cm tall and weighs 154 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.
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
1atrial fibrillation
2first-degree AV block
3junctional rhythm
4sinus bradycardia
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
1second-degree AV block type II
2third-degree (complete) AV block
3second-degree AV block type I (Wenckebach)
4junctional rhythm
13.Prioritization & delegationMedium
A patient taking warfarin has an INR of 5.2 and no signs of bleeding. What should the nurse do?
AGive the usual dose and recheck the INR next month
BGive a double dose to correct the result
CHold the warfarin dose and inform the provider
DEncourage the patient to take aspirin for pain
14.Prioritization & delegationHard
A patient with major depression has been withdrawn for weeks but is suddenly calm and cheerful and gives away her belongings. What should the nurse suspect?
AA full recovery, so observation can be reduced
BThat she is getting ready for discharge as planned
CA raised risk of suicide, because she may have made a decision
DA side effect of her antidepressant medicine that needs no special action
15.Infection control & patient safetyMedium
A small spill of blood is found on the floor. How should it be cleaned?
AWipe it up quickly with a dry cloth using bare hands, then wash the hands well
BCover it with a clean sheet and keep working
CWear gloves, absorb the blood, then clean the area with an approved disinfectant
DLeave it until housekeeping arrives the next morning
16.Infection control & patient safetyHard
A patient is prescribed hydralazine, but the pharmacy has sent hydroxyzine. What should the nurse do?
AGive half the dose of hydroxyzine as a compromise
BGive it now and tell the prescriber afterwards
CGive it, because the two drug names are almost the same
DNot give it, and contact the pharmacy to obtain the correct drug
17.Lab values & electrolytesMedium
A 55-year-old has a positive fecal immunochemical test (FIT) during routine screening. What is the usual next step?
ARepeat the test in 10 years
BNo action if there are no symptoms
CReferral for colonoscopy
DStart an iron supplement only
18.Lab values & electrolytesHard
Which cerebrospinal fluid (CSF) pattern most strongly suggests bacterial meningitis?
AClear fluid, normal glucose, mildly raised protein, lymphocytes
BClear fluid, high glucose, low protein, many red cells
CCloudy fluid, low glucose, high protein, many neutrophils
DClear fluid, normal glucose, normal protein, no white cells
3Solutions
1.Nursing fundamentals
Answer: D · Patients who know their breathing is watched tend to change it
Why this is the answer
Breathing can be changed on purpose, so a patient who is aware of being watched may breathe differently. Counting unobtrusively for a full minute gives a more accurate rate.
Answer
D · Patients who know their breathing is watched tend to change it
2.Nursing fundamentals
Answer: C · Urgent or emergency response with immediate senior clinical review
Why this is the answer
A NEWS2 of 7 or more calls for an emergency response: continuous monitoring and immediate assessment by a clinician with critical care skills.
Answer
C · Urgent or emergency response with immediate senior clinical review
3.Clinical nursing
Answer: D · Sepsis
Why this is the answer
These three signs form the qSOFA criteria and suggest a high risk of poor outcome from sepsis. Escalate urgently and start the sepsis pathway.
Answer
D · Sepsis
4.Clinical nursing
Answer: D · Regular full sets of observations with an early warning score and trend review
Why this is the answer
Track-and-trigger systems such as NEWS2 combine respiratory rate, SpO2, blood pressure, pulse, consciousness and temperature to identify deterioration early.
Answer
D · Regular full sets of observations with an early warning score and trend review
5.Arterial blood gas interpretation
Answer: partially compensated
Reading a blood gas (ROME): first the pH: below 7.35 is acidaemia, above 7.45 alkalaemia. Then find the value that explains it. PaCO₂ (normal 35–45 mmHg, 4.7–6.0 kPa) is the respiratory part and moves Opposite to the pH in a respiratory disorder; HCO₃⁻ (normal 22–26 mmol/L) is the metabolic part and moves in the same direction as the pH (Respiratory Opposite, Metabolic Equal). The other value shows the compensation: normal means uncompensated; abnormal in the direction that pulls the pH back while the pH is still abnormal means partially compensated; a normal pH with both values abnormal means fully compensated. Ranges differ slightly between laboratories; these are practice values.
ROME, value by value
pH 7.31: acidaemia (below 7.35)
PaCO₂ 33 mmHg: low (35–45)
HCO₃⁻ 16 mmol/L: low (22–26)
Compensation
partially compensated
Answer
partially compensated
6.Arterial blood gas interpretation
Answer: A–a gradient = 172.4 mmHg
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.
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 97% → 0
on oxygen → 2
SBP 142 mmHg → 0
HR 64/min → 0
alert (A) → 0
T 38.8 °C → 1
Add
NEWS2 = 0 + 0 + 2 + 0 + 0 + 0 + 1 = 3
Answer
NEWS2 = 3
8.Clinical assessment scores
Answer: high 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: yes → 25
secondary diagnosis: yes → 15
ambulatory aid: crutches, cane or walker → 15
IV therapy or saline lock: no → 0
gait: weak → 10
mental status: overestimates or forgets limits → 15
Add
Morse total = 25 + 15 + 15 + 0 + 10 + 15 = 80
Risk level
80 → high risk
Answer
high risk
9.Enteral & parenteral nutrition calculations
Answer: V = 218 mL
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.
Fluid goal
30·77 = 2310 mL/day
Free water from the formula
55·24 = 1320 mL
1320·0.76 = 1003 mL
Water still needed
2310 − 1003 = 1307 mL/day
Volume per flush
24/4 = 6 flushes
V = 1307/6 = 217.8 ≈ 218 mL
Answer
V = 218 mL
10.Enteral & parenteral nutrition calculations
Answer: P = 194 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 = 154/1.83² = 45.99 kg/m²
Ideal body weight (Devine)
183 cm/2.54 = 72.05 in
IBW = 50 + 2.3·(72.05 − 60) = 77.71 kg
Protein goal
BMI 40 or more: 2.5 g per kg of ideal body weight.
P = 2.5·77.71 = 194.3 ≈ 194 g/day
Answer
P = 194 g/day
11.ECG rhythm strip interpretation
Answer: junctional rhythm
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 = 36 small boxes, 1500 ÷ 36 ≈ 42 per minute.
2. Rhythm: regular, every R–R is 1.44 s.
3. P waves: inverted, just after each QRS.
4. PR interval: not measurable.
5. QRS: 0.10 s, narrow (below 0.12 s).
Interpretation
junctional rhythm
Answer
junctional rhythm
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 = 54 small boxes, 1500 ÷ 54 ≈ 28 per minute.
2. Rhythm: R–R regular (2.16 s) and P–P regular (0.64 s), but the two are independent.
3. P waves: upright and regular at 94 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: 0.14 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: C · Hold the warfarin dose and inform the provider
Why this is the answer
An INR well above target raises the risk of serious bleeding. The nurse holds the dose, informs the provider and watches for bleeding. Without bleeding, holding warfarin is usually enough at this level; vitamin K is mainly used for very high INRs or bleeding.
Answer
C · Hold the warfarin dose and inform the provider
14.Prioritization & delegation
Answer: C · A raised risk of suicide, because she may have made a decision
Why this is the answer
A sudden lift in mood with giving away belongings can mean the patient has decided to end her life. The nurse asks directly about suicidal thoughts and keeps her safe.
Answer
C · A raised risk of suicide, because she may have made a decision
15.Infection control & patient safety
Answer: C · Wear gloves, absorb the blood, then clean the area with an approved disinfectant
Why this is the answer
Blood spills are cleaned promptly by staff wearing gloves. The blood is absorbed with disposable material, then the area is cleaned and disinfected with a hospital disinfectant, and waste goes into clinical waste.
Answer
C · Wear gloves, absorb the blood, then clean the area with an approved disinfectant
16.Infection control & patient safety
Answer: D · Not give it, and contact the pharmacy to obtain the correct drug
Why this is the answer
Hydralazine is an antihypertensive, while hydroxyzine is an antihistamine used for itching and anxiety. Giving the wrong drug is a medication error. The nurse withholds it, gets the correct drug and reports the dispensing error.
Answer
D · Not give it, and contact the pharmacy to obtain the correct drug
17.Lab values & electrolytes
Answer: C · Referral for colonoscopy
Why this is the answer
A positive FIT means hidden blood in the stool, which may come from a polyp, cancer or other lesion, so a colonoscopy is needed to find the source. A positive screening test is never ignored, even without symptoms.Checked against:Fecal Occult Blood Test (FOBT) · MedlinePlus (NIH) (2024)
Answer
C · Referral for colonoscopy
18.Lab values & electrolytes
Answer: C · Cloudy fluid, low glucose, high protein, many neutrophils
Why this is the answer
Bacterial meningitis typically gives cloudy CSF with many neutrophils, high protein and low glucose, because bacteria and white cells use glucose. Viral meningitis usually shows lymphocytes with a normal glucose; option C is normal CSF.Checked against:CSF glucose test · MedlinePlus (NIH) (2025); CSF cell count · MedlinePlus (NIH) (2025); CSF total protein · MedlinePlus (NIH) (2025)
Answer
C · Cloudy fluid, low glucose, high protein, many neutrophils