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 combination of signs suggests a wound infection?
AA dry scab with no pain
BMild itching as the edges close
CPink granulation tissue, mild serous fluid and a shrinking wound
DIncreasing redness, warmth, swelling, pain and pus
2.Nursing fundamentalsHard
A patient has been taught breathing exercises before surgery. Which statement shows a need for further teaching?
A"I'll ask for pain relief if pain stops me breathing deeply."
B"I'll hold a pillow over the wound when I cough."
C"I'll take some slow deep breaths every hour."
D"I'll avoid coughing so I don't hurt my stitches."
3.Clinical nursingMedium
A patient who injects drugs has a fever, a new heart murmur and small dark lines under the nails. What is the likely diagnosis?
AInfective endocarditis
BMyocardial infarction
CPericarditis
DRheumatic fever
4.Clinical nursingHard
A patient with myasthenia gravis develops increasing difficulty swallowing and weak, shallow breathing. What is the main danger?
ASevere hypertension from anxiety
BA sudden rise in blood glucose from the stress
CRespiratory failure from a myasthenic crisis
DA urinary tract infection
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 140 mmol/L, glucose 31.1 mmol/L and urea 19.9 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 140 mmol/Lglucose 31.1 mmol/Lurea 19.9 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
A practice gas shows pH 7.31, PaCO₂ 33 mmHg (4.4 kPa) and HCO₃⁻ 16 mmol/L, with Na⁺ 139 and Cl⁻ 91 mmol/L. Use the anion gap and the delta ratio to click the best interpretation.
Practice exercise (made-up values, not clinical guidance). A patient has a pulse of 90/min and a blood pressure of 72/43 mmHg. Find the shock index SI = HR/SBP. Round to two decimal places.
HR 90/minBP 72/43 mmHg
SI =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 9/min, SpO₂ 90% on room air, blood pressure 136/82 mmHg, pulse 82/min, alert, temperature 36.4 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). Use the Devine formula to find the ideal body weight IBW of a woman who is 156 cm tall (1 in = 2.54 cm). Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A child who weighs 17 kg receives 7.5% dextrose at 53 mL/h. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
17 kg7.5%53 mL/h
GIR = mg/kg/min
11.ECG rhythm strip interpretationMedium
This lead II strip shows sinus rhythm with one pause. Measure the pause, the R–R interval across it, in seconds.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
pause = s
12.ECG rhythm strip interpretationHard
Interpret this lead II strip with the five steps in order: rate, rhythm, P waves, PR interval, QRS duration. At which step do you find the first abnormal finding? Click it.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
1rate
2rhythm
3P waves
4PR interval
5QRS duration
13.Prioritization & delegationMedium
A patient with diabetes is unresponsive and has a blood glucose of 40 mg/dL (2.2 mmol/L). What should the nurse do first?
AWait 15 minutes and recheck the glucose
BPour orange juice into the patient’s mouth
CGive IV dextrose or glucagon as prescribed
DGive the scheduled dose of insulin
14.Prioritization & delegationHard
A patient at 34 weeks of pregnancy has painless, bright red vaginal bleeding. Which action should the nurse avoid?
AWeighing the pads to estimate blood loss
BMeasuring the blood pressure and pulse
CMonitoring the fetal heart rate
DA vaginal examination
15.Infection control & patient safetyMedium
Which nurse should not be assigned to a patient with a sealed radioactive implant?
AA nurse who has worked on the unit for two years
BA nurse who is pregnant
CA nurse trained in radiation safety
DA nurse wearing a dosimeter badge
16.Infection control & patient safetyHard
Ten minutes into a red blood cell transfusion, the patient reports chills and low back pain and has a new fever. What should the nurse do first?
ASlow the transfusion and recheck vital signs in 15 minutes
BCall the blood bank and let the transfusion continue
CStop the transfusion
DGive an antipyretic and continue the transfusion
17.Lab values & electrolytesMedium
A patient takes low-dose methotrexate weekly for rheumatoid arthritis. Which laboratory tests are monitored regularly?
ASerum lithium, sodium and urine specific gravity
BTroponin, creatine kinase and myoglobin
CSerum amylase, lipase and blood ketones
DComplete blood count, liver tests and kidney function
18.Lab values & electrolytesHard
The nurse teaches a patient with severe neutropenia after chemotherapy. Which statement shows a need for further teaching?
A"I'll wash my hands before eating and after the toilet"
B"I'll call the clinic if my temperature rises"
C"I'll check my temperature rectally to be accurate"
D"I'll avoid people who have a cold or the flu"
3Solutions
1.Nursing fundamentals
Answer: D · Increasing redness, warmth, swelling, pain and pus
Why this is the answer
Spreading redness, heat, swelling, pain, pus or an unpleasant smell suggest infection, sometimes with fever. Pink granulation tissue and itching are signs of normal healing.
Answer
D · Increasing redness, warmth, swelling, pain and pus
2.Nursing fundamentals
Answer: D · "I'll avoid coughing so I don't hurt my stitches."
Why this is the answer
Avoiding coughing lets secretions collect and raises the risk of chest infection. Splinting the wound, deep breathing and good pain control are correct.
Answer
D · "I'll avoid coughing so I don't hurt my stitches."
3.Clinical nursing
Answer: A · Infective endocarditis
Why this is the answer
Infective endocarditis causes fever and a new or changing murmur, sometimes with splinter haemorrhages. Several sets of blood cultures are taken before long-course IV antibiotics.
Answer
A · Infective endocarditis
4.Clinical nursing
Answer: C · Respiratory failure from a myasthenic crisis
Why this is the answer
In a myasthenic crisis, weakness of respiratory and bulbar muscles can cause aspiration and respiratory failure. Breathing function is monitored closely and ventilation may be needed.
Answer
C · Respiratory failure from a myasthenic crisis
5.Arterial blood gas interpretation
Answer: Osm = 331 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 = 2·140 + 31.1 + 19.9 = 331 ≈ 331 mOsm/kg
Answer
Osm = 331 mOsm/kg
6.Arterial blood gas interpretation
Answer: added metabolic alkalosis
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 = 139 − (91 + 16) = 32
Delta ratio
(32 − 12)/(24 − 16) = 2.5
added metabolic alkalosis
Answer
added metabolic alkalosis
7.Clinical assessment scores
Answer: SI = 1.25
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.
Shock index
SI = 90/72 = 1.25
Answer
SI = 1.25
1 or more: a warning sign of shock in this practice case.
8.Clinical assessment scores
Answer: low–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 9/min → 1
SpO₂ 90% → 3
on air → 0
SBP 136 mmHg → 0
HR 82/min → 0
alert (A) → 0
T 36.4 °C → 0
Total and red scores
NEWS2 = 1 + 3 + 0 + 0 + 0 + 0 + 0 = 4
At least one parameter scores 3.
Risk group
low–medium
Answer
low–medium
A single score of 3 needs an urgent review even when the total is low.
9.Enteral & parenteral nutrition calculations
Answer: IBW = 48.8 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
156 cm/2.54 = 61.42 in
Ideal body weight (Devine)
IBW = 45.5 + 2.3·(61.42 − 60) = 48.76 ≈ 48.8 kg
Answer
IBW = 48.8 kg
10.Enteral & parenteral nutrition calculations
Answer: GIR = 3.9 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 concentration
7.5% = 75 mg/mL
Dextrose per minute
75·53/60 = 66.25 mg/min
Per kilogram
GIR = 66.25/17 = 3.897 ≈ 3.9 mg/kg/min
Answer
GIR = 3.9 mg/kg/min
Shortcut: GIR = % dextrose × mL/h/(6 × kg).
11.ECG rhythm strip interpretation
Answer: pause = 1.44 s
Narrow-complex tachycardia and pauses: supraventricular tachycardia (SVT) is a regular tachycardia at about 150–250/min with narrow QRS complexes; the P waves are usually not visible because they are hidden in the QRS complex or the T wave. Sinus tachycardia in an adult at rest is usually below about 150/min and has a visible P wave before every QRS; atrial flutter with 2:1 conduction often runs at about 150/min and shows sawtooth waves. In sinus arrest the sinus node stops firing for a moment: a pause with no P wave and no QRS whose length is not a whole number of P–P cycles (a pause of exactly two or three cycles points to sinus exit block instead).
Measure
36 small boxes from R to R across the pause
Convert
pause = 36 × 0.04 s = 1.44 s
Compare with P–P
1.44 ÷ 0.88 ≈ 1.6 P–P cycles, not a whole number
Answer
pause = 1.44 s
No P wave appears in the pause, and the pause is not a whole number of P–P cycles: sinus arrest. A pause of exactly two or three cycles would point to sinus exit block.
12.ECG rhythm strip interpretation
Answer: PR interval
Five steps for every strip: 1. rate (300 or 1500 method, or the 6-second method if irregular); 2. rhythm: are the R–R intervals equal; 3. P waves: present, upright in lead II, one before every QRS and all alike; 4. PR interval: 0.12–0.20 s and constant; 5. QRS duration: below 0.12 s. Only after the five steps name the rhythm. Normal sinus rhythm passes all five: 60–100/min, regular, upright P before every QRS, PR 0.12–0.20 s, QRS below 0.12 s.
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: upright, one before every QRS, all alike.
4. PR interval: 0.30 s, constant, longer than 0.20 s.
5. QRS: 0.10 s, narrow (below 0.12 s).
First abnormal step
PR interval → first-degree AV block
Answer
PR interval
13.Prioritization & delegation
Answer: C · Give IV dextrose or glucagon as prescribed
Why this is the answer
An unconscious patient must not be given anything by mouth because of aspiration risk. IV dextrose or glucagon raises the glucose quickly.
Answer
C · Give IV dextrose or glucagon as prescribed
14.Prioritization & delegation
Answer: D · A vaginal examination
Why this is the answer
Painless, bright red bleeding suggests placenta previa. A vaginal examination could cause severe hemorrhage, so it is avoided until the placenta position is known.
Answer
D · A vaginal examination
15.Infection control & patient safety
Answer: B · A nurse who is pregnant
Why this is the answer
Pregnant staff and visitors are not assigned to patients with radioactive implants. Other staff limit the time spent with the patient, keep their distance, use shielding and wear a dosimeter.
Answer
B · A nurse who is pregnant
16.Infection control & patient safety
Answer: C · Stop the transfusion
Why this is the answer
These signs suggest an acute transfusion reaction, possibly hemolytic. The nurse stops the transfusion at once, keeps the IV open with normal saline through new tubing, assesses the patient and notifies the provider and blood bank.
Answer
C · Stop the transfusion
17.Lab values & electrolytes
Answer: D · Complete blood count, liver tests and kidney function
Why this is the answer
Methotrexate can cause bone marrow suppression, liver toxicity and, as it is cleared by the kidneys, toxicity when kidney function falls. The CBC, liver tests and creatinine are checked regularly, and folic acid is usually given to reduce adverse effects.Checked against:Methotrexate · StatPearls (NCBI Bookshelf) (2024)
Answer
D · Complete blood count, liver tests and kidney function
18.Lab values & electrolytes
Answer: C · "I'll check my temperature rectally to be accurate"
Why this is the answer
Rectal temperatures, suppositories and enemas are avoided in neutropenia, because injury to the rectal mucosa can let bacteria into the blood. Prompt reporting of fever, hand hygiene and avoiding sick contacts are correct.
Answer
C · "I'll check my temperature rectally to be accurate"