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's radial pulse is irregular. How should you count it?
AOnly on the automatic blood pressure machine
BFor 10 seconds and multiply by six
CFor a full 60 seconds, ideally at the apex of the heart
DFor 15 seconds and multiply by four
2.Nursing fundamentalsHard
Which feature best helps distinguish delirium from dementia?
ADementia always improves once the underlying cause has been treated
BDelirium starts suddenly and attention fluctuates during the day
CDementia starts within hours of an infection
DDelirium always lasts for many years
3.Clinical nursingMedium
For a patient in skin traction on the leg, which is correct?
AThe rope is tied to the bed frame to keep it still
BThe weights hang freely and do not rest on the bed or floor
CThe weights are removed whenever the patient feels uncomfortable
DThe weights rest on the floor overnight
4.Clinical nursingHard
A patient with small cell lung cancer has hyponatraemia, concentrated urine and no signs of dehydration. Which condition and first measure fit best?
ACushing's syndrome, managed with potassium
BDehydration, managed with an IV fluid bolus
CDiabetes insipidus, managed with extra fluids
DSIADH, often managed first with fluid restriction
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 71 mmHg (9.5 kPa). Use the rule that in chronic respiratory acidosis HCO₃⁻ rises by 3.5 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 18/min, SpO₂ 97% on supplemental oxygen, blood pressure 150/90 mmHg, pulse 130/min, alert, temperature 35.2 °C. What is the NEWS2 total score?
RR 18SpO₂ 97%O₂SBP 150HR 130AT 35.2 °C
NEWS2 =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 32/min, SpO₂ 96% on room air, blood pressure 106/64 mmHg, pulse 92/min, alert, temperature 39.0 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). A 52 kg patient needs 2 g of protein per kg a day. The tube feed contains 63 g of protein per litre and runs at 45 mL/h for 24 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). A 75 kg adult receives 1500 mL of parenteral nutrition containing 10% dextrose, infused over 12 hours. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
75 kg1500 mLdextrose 10%12 h
GIR = mg/kg/min
11.ECG rhythm strip interpretationMedium
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 rhythm with PVCs
2normal sinus rhythm
3atrial fibrillation
4ventricular bigeminy
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
2second-degree AV block type II
3dual-chamber (AV) paced rhythm
4paced rhythm, failure to capture
13.Prioritization & delegationMedium
A patient with severe neutropenia needs a room. Which roommate is the safest choice?
AA patient with an infected, draining leg wound
BA patient with influenza
CA patient with C. difficile diarrhea
DA patient after a knee replacement with no signs of infection
14.Prioritization & delegationHard
After report, which patient should the nurse assess first?
ACOPD on 2 L/min oxygen: SpO₂ 90%, respiratory rate 22/min, at usual baseline
B1 hour after femoral cardiac catheterization: new back pain, pulse 118/min, BP 92/58 mmHg
CType 2 diabetes: glucose 210 mg/dL (11.7 mmol/L) before lunch, no symptoms
DDay 2 after gallbladder surgery: pain 6/10, next analgesic due in 30 minutes
15.Infection control & patient safetyMedium
An order uses the abbreviation “MS”. Why is this unsafe?
AIt can mean either morphine sulfate or magnesium sulfate
BIt is the abbreviation for milliseconds, not a drug
CIt is reserved for drugs used in multiple sclerosis
DIt means the drug must be given by mouth only
16.Infection control & patient safetyHard
A nurse cannot find a confused patient who was in their room 15 minutes ago. What should the nurse do first?
AWait an hour in case the patient comes back
BCall the family to ask whether the patient has gone home on their own
CDocument the absence at the end of the shift
DAlert staff and security at once, following the missing-patient procedure
17.Lab values & electrolytesMedium
A patient starts high-dose prednisone. Which laboratory change should the nurse expect?
AA fall in serum sodium
BA rise in serum potassium
CA rise in blood glucose
DA fall in the white cell count
18.Lab values & electrolytesHard
Which set of results best shows that diabetic ketoacidosis is resolving?
AA closing anion gap with a rising bicarbonate and pH
BA falling glucose with a still widening anion gap
CA rising potassium with a falling bicarbonate
DA falling glucose with a falling serum bicarbonate
3Solutions
1.Nursing fundamentals
Answer: C · For a full 60 seconds, ideally at the apex of the heart
Why this is the answer
An irregular pulse should be counted for a full minute. An apical count with a stethoscope is more accurate, as some beats may be too weak to feel at the wrist.
Answer
C · For a full 60 seconds, ideally at the apex of the heart
2.Nursing fundamentals
Answer: B · Delirium starts suddenly and attention fluctuates during the day
Why this is the answer
Delirium develops over hours to days with fluctuating attention and awareness, often from a physical cause. Dementia develops gradually over months or years. People with dementia are at higher risk of delirium.
Answer
B · Delirium starts suddenly and attention fluctuates during the day
3.Clinical nursing
Answer: B · The weights hang freely and do not rest on the bed or floor
Why this is the answer
Weights must hang freely so the pull is continuous and in line. Nurses also check the skin, circulation and sensation of the limb.
Answer
B · The weights hang freely and do not rest on the bed or floor
4.Clinical nursing
Answer: D · SIADH, often managed first with fluid restriction
Why this is the answer
In SIADH, excess ADH makes the kidneys retain water, so blood sodium is diluted while urine is concentrated. Small cell lung cancer is a classic cause; fluid restriction is a common first step.
Answer
D · SIADH, often managed first with fluid restriction
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 34.85 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
|71 − 40| = 31 mmHg → 3.1 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 3.5·3.1 = 34.85 mmol/L
Answer
HCO₃⁻ = 34.85 mmol/L
6.Arterial blood gas interpretation
Answer: AGc = 21.75 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 = 145 − (115 + 14) = 16
Correction for albumin
16 + 0.25·(40 − 17) = 21.75 mmol/L
Answer
AGc = 21.75 mmol/L
Above about 12 after correction: a high anion gap.
7.Clinical assessment scores
Answer: NEWS2 = 5
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 18/min → 0
SpO₂ 97% → 0
on oxygen → 2
SBP 150 mmHg → 0
HR 130/min → 2
alert (A) → 0
T 35.2 °C → 1
Add
NEWS2 = 0 + 0 + 2 + 0 + 2 + 0 + 1 = 5
Answer
NEWS2 = 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 32/min → 3
SpO₂ 96% → 0
on air → 0
SBP 106 mmHg → 1
HR 92/min → 1
alert (A) → 0
T 39.0 °C → 1
Total and red scores
NEWS2 = 3 + 0 + 0 + 1 + 1 + 0 + 1 = 6
At least one 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: ΔP = 36 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
2·52 = 104 g/day
Protein from the feed
45·24 = 1080 mL = 1.08 L
1.08·63 = 68.04 g/day
Shortfall
ΔP = 104 − 68.04 = 35.96 ≈ 36 g/day
Answer
ΔP = 36 g/day
10.Enteral & parenteral nutrition calculations
Answer: GIR = 2.78 mg/kg/min
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.
Dextrose in the bag
10·1500/100 = 150 g = 150 000 mg
Minutes of infusion
12·60 = 720 min
Glucose infusion rate
GIR = 150 000/(75·720) = 2.778 ≈ 2.78 mg/kg/min
Answer
GIR = 2.78 mg/kg/min
11.ECG rhythm strip interpretation
Answer: ventricular bigeminy
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: 8 QRS complexes in 6 s, × 10 = 80 per minute.
2. Rhythm: regularly irregular, a short and a long R–R alternate (0.44 s and 1.00 s).
3. P waves: upright before every narrow QRS; none before the early wide beats.
4. PR interval: 0.18 s, constant, within 0.12–0.20 s.
5. QRS: 0.08 s in the sinus beats; the early beats are wide (0.16 s) and bizarre, with the T wave pointing the other way.
Interpretation
ventricular bigeminy
Answer
ventricular bigeminy
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: 5 QRS complexes in 6 s, × 10 = 50 per minute.
2. Rhythm: the pacing spikes are regular (every 0.96 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: 0.14 s and wide after the captured spikes; one spike is 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: D · A patient after a knee replacement with no signs of infection
Why this is the answer
A neutropenic patient cannot fight infection well, so the roommate must not have a transmissible infection. A clean postoperative patient is the safest choice; ideally the neutropenic patient has a single room.
Answer
D · A patient after a knee replacement with no signs of infection
14.Prioritization & delegation
Answer: B · 1 hour after femoral cardiac catheterization: new back pain, pulse 118/min, BP 92/58 mmHg
Why this is the answer
Back pain, tachycardia and hypotension after a femoral puncture suggest retroperitoneal bleeding, which can be hidden and fatal. The COPD patient is at baseline, the pain is expected and being treated, and the glucose is high but not an emergency.
Answer
B · 1 hour after femoral cardiac catheterization: new back pain, pulse 118/min, BP 92/58 mmHg
15.Infection control & patient safety
Answer: A · It can mean either morphine sulfate or magnesium sulfate
Why this is the answer
“MS”, “MSO4” and “MgSO4” can be confused, and giving one drug instead of the other can cause serious harm. Drug names are written in full.
Answer
A · It can mean either morphine sulfate or magnesium sulfate
16.Infection control & patient safety
Answer: D · Alert staff and security at once, following the missing-patient procedure
Why this is the answer
A missing vulnerable patient is an emergency. The nurse immediately activates the facility’s missing-patient procedure so a search starts, and the provider and family are informed per policy.
Answer
D · Alert staff and security at once, following the missing-patient procedure
17.Lab values & electrolytes
Answer: C · A rise in blood glucose
Why this is the answer
Glucocorticoids raise blood glucose by increasing glucose production and reducing insulin sensitivity. They also tend to lower potassium, retain sodium and raise the white cell count by releasing neutrophils into the blood.Checked against:Blood Glucose Test · MedlinePlus (NIH) (2024)
Answer
C · A rise in blood glucose
18.Lab values & electrolytes
Answer: A · A closing anion gap with a rising bicarbonate and pH
Why this is the answer
DKA has resolved when the ketoacidosis has cleared: ketones fall, the anion gap normalizes, bicarbonate rises and the pH returns towards normal. Glucose alone is a poor guide, because it falls earlier.
Answer
A · A closing anion gap with a rising bicarbonate and pH