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?
AFor a full 60 seconds, ideally at the apex of the heart
BOnly on the automatic blood pressure machine
CFor 10 seconds and multiply by six
DFor 15 seconds and multiply by four
2.Nursing fundamentalsHard
A pressure ulcer shows full-thickness tissue loss with exposed bone. How is it classified?
ACategory 2
BCategory 3
CSuspected deep tissue injury
DCategory 4
3.Clinical nursingMedium
Why must a patient with a new coronary stent not stop their antiplatelet medicines without specialist advice?
AStopping causes severe low blood pressure
BStopping causes immediate kidney failure
CStopping early greatly increases the risk of a clot forming in the stent
DThe stent will dissolve if the drugs are stopped before the course ends
4.Clinical nursingHard
A nurse teaches a patient with reflux disease. Which statement shows a need for further teaching?
A"I will try to lose some weight over the next months."
B"I will raise the head of my bed with blocks."
C"I will cut down on alcohol."
D"A big meal just before bed is fine if I take my tablet."
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 130 mmol/L, glucose 30 mmol/L and urea 6.2 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 130 mmol/Lglucose 30 mmol/Lurea 6.2 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
Practice values: Na⁺ 140, Cl⁻ 90 and HCO₃⁻ 15 mmol/L. Calculate the delta ratio (AG − 12)/(24 − HCO₃⁻), using AG = Na⁺ − (Cl⁻ + HCO₃⁻). Give two decimals.
Na⁺ 140 mmol/LCl⁻ 90 mmol/LHCO₃⁻ 15 mmol/L
delta ratio =
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). A patient has a pulse of 73/min and a blood pressure of 84/55 mmHg. Find the shock index SI = HR/SBP. Round to two decimal places.
HR 73/minBP 84/55 mmHg
SI =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). An adult weighs 77 kg and is 155 cm tall. Calculate the BMI and click the WHO weight category.
Practice exercise (made-up values, not clinical guidance). A 51 kg patient has a fluid goal of 30 mL/kg/day and receives all fluid through a feeding tube. The formula is 81% free water and runs at 70 mL/h for 20 hours a day. The rest of the fluid is given as water flushes every 8 hours. What volume V is each flush? Round to the nearest whole number.
Practice exercise (made-up values, not clinical guidance). A child who weighs 7 kg receives 5% dextrose at 52 mL/h. Find the glucose infusion rate GIR in mg/kg/min. Round to two decimal places.
7 kg5%52 mL/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
1atrial fibrillation
2junctional rhythm
3sinus arrhythmia
4atrial flutter, 4:1 conduction
12.ECG rhythm strip interpretationHard
Identify the rhythm on this 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
1asystole
2third-degree (complete) AV block
3junctional rhythm
4sinus bradycardia
13.Prioritization & delegationMedium
A nursing assistant reports on four patients. Which report needs the nurse’s attention first?
AA patient has passed 300 mL of urine in the past 6 hours
BA patient asks for an extra pillow
CA patient one day after abdominal surgery is newly restless and has a heart rate of 124/min
DA patient with COPD has an SpO₂ of 90% at rest, which matches their usual values
14.Prioritization & delegationHard
A nurse sees a colleague put a vial of an opioid into their own pocket instead of returning it. What should the nurse do?
AReport it to the nurse manager according to policy
BSay nothing, because it is not their business
CTell the patients to watch the colleague carefully
DAsk the colleague to share the vial with them
15.Infection control & patient safetyMedium
Sterile saline is spilled on a sterile drape that lies on a non-sterile table. What does this mean?
AOnly the wet part is contaminated, so items can be moved to the dry part
BThe field is contaminated, because moisture can carry organisms through the drape
CThe field becomes sterile again when it dries
DThe field stays sterile, because saline is sterile
16.Infection control & patient safetyHard
Which patient with a suspected infection meets at least two SIRS criteria?
ATemperature 36.8 °C and respiratory rate 18/min
BTemperature 37.2 °C and heart rate 80/min
CRespiratory rate 16/min and WBC 8,000/mm3
DTemperature 38.6 °C and heart rate 112/min
17.Lab values & electrolytesMedium
A patient on phenytoin has a level of 28 mcg/mL (usual range about 10–20 mcg/mL). Which findings would the nurse expect?
ATall, peaked T waves
BHyperactive behavior and insomnia only
CNystagmus, unsteady gait and slurred speech
DHunger and weight gain
18.Lab values & electrolytesHard
After a crush injury, a patient's urine dipstick is strongly positive for blood, but microscopy shows almost no red cells. CK is very high. What best explains this?
AThe sample was contaminated with menstrual blood
BA kidney stone is scraping the ureter lining
CMyoglobin from damaged muscle is in the urine
DBleeding is coming from the bladder lining
3Solutions
1.Nursing fundamentals
Answer: A · 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
A · For a full 60 seconds, ideally at the apex of the heart
2.Nursing fundamentals
Answer: D · Category 4
Why this is the answer
Category 4 (Stage 4 in the US NPIAP system) involves full-thickness tissue loss with exposed bone, tendon or muscle. It carries a high risk of osteomyelitis and needs specialist input.
Answer
D · Category 4
3.Clinical nursing
Answer: C · Stopping early greatly increases the risk of a clot forming in the stent
Why this is the answer
Dual antiplatelet therapy prevents stent thrombosis while the stent becomes covered by the artery lining. Stopping early can cause a sudden myocardial infarction.
Answer
C · Stopping early greatly increases the risk of a clot forming in the stent
4.Clinical nursing
Answer: D · "A big meal just before bed is fine if I take my tablet."
Why this is the answer
Large late meals increase reflux even when a PPI is taken. Raising the head of the bed, losing weight and reducing alcohol are correct measures.
Answer
D · "A big meal just before bed is fine if I take my tablet."
5.Arterial blood gas interpretation
Answer: Osm = 296 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 = 2·130 + 30 + 6.2 = 296.2 ≈ 296 mOsm/kg
Answer
Osm = 296 mOsm/kg
6.Arterial blood gas interpretation
Answer: delta ratio = 2.556
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 = 140 − (90 + 15) = 35
Delta ratio
(35 − 12)/(24 − 15) = 23/9 = 2.556
Answer
delta ratio = 2.556
Above 2: an added metabolic alkalosis.
7.Clinical assessment scores
Answer: SI = 0.87
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 = 73/84 = 0.869 ≈ 0.87
Answer
SI = 0.87
Above the usual 0.5–0.7.
8.Clinical assessment scores
Answer: obesity class I
Body mass index: BMI = weight (kg)/height (m)², with the height converted to metres first. With pounds and inches, BMI = 703 × weight (lb)/height (in)². WHO adult categories: below 18.5 underweight, 18.5–24.9 healthy weight, 25.0–29.9 overweight, 30.0–34.9 obesity class I, 35.0–39.9 obesity class II and 40 or more obesity class III.
BMI
BMI = 77/1.55² = 32.05
Category
obesity class I
Answer
obesity class I
9.Enteral & parenteral nutrition calculations
Answer: V = 132 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
30·51 = 1530 mL/day
Free water from the formula
70·20 = 1400 mL
1400·0.81 = 1134 mL
Water still needed
1530 − 1134 = 396 mL/day
Volume per flush
24/8 = 3 flushes
V = 396/3 = 132 mL
Answer
V = 132 mL
10.Enteral & parenteral nutrition calculations
Answer: GIR = 6.19 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
5% = 50 mg/mL
Dextrose per minute
50·52/60 = 43.33 mg/min
Per kilogram
GIR = 43.33/7 = 6.19 mg/kg/min
Answer
GIR = 6.19 mg/kg/min
Shortcut: GIR = % dextrose × mL/h/(6 × kg).
11.ECG rhythm strip interpretation
Answer: atrial fibrillation
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: irregularly irregular, R–R from 0.46 to 1.02 s with no pattern.
3. P waves: none; the baseline shows small irregular fibrillatory waves.
4. PR interval: not measurable.
5. QRS: 0.06 s, narrow (below 0.12 s).
Interpretation
atrial fibrillation
Answer
atrial fibrillation
12.ECG rhythm strip interpretation
Answer: asystole
Ventricular rhythms: ventricular tachycardia is a run of three or more wide (0.12 s or more) complexes in a row at more than 100/min, usually 150–250/min, regular, without related P waves. Ventricular fibrillation is a chaotic, irregular waveform with no identifiable P waves, QRS complexes or T waves and no countable rate. Asystole is an almost flat line with no ventricular activity; a flat line is always confirmed by checking the patient, the leads and the gain and a second lead. In resuscitation guidelines VF and pulseless VT are the shockable rhythms and asystole is not.
Five steps
1. Rate: no countable ventricular rate.
2. Rhythm: none; an almost flat line.
3. P waves: none identifiable.
4. PR interval: not measurable.
5. QRS: no QRS complexes.
Interpretation
asystole
Answer
asystole
A flat line is always checked: look at the patient, the leads and the gain, and view a second lead, because a loose electrode or fine VF can look like asystole.
13.Prioritization & delegation
Answer: C · A patient one day after abdominal surgery is newly restless and has a heart rate of 124/min
Why this is the answer
New restlessness with a fast heart rate after surgery can mean bleeding, sepsis or hypoxia. An SpO₂ of 90% is expected for this COPD patient, and 300 mL in 6 hours (50 mL/h) is an adequate urine output.
Answer
C · A patient one day after abdominal surgery is newly restless and has a heart rate of 124/min
14.Prioritization & delegation
Answer: A · Report it to the nurse manager according to policy
Why this is the answer
Suspected drug diversion must be reported through the proper channel, usually the manager. It protects patients and allows the colleague to get help; staying silent is not acceptable.
Answer
A · Report it to the nurse manager according to policy
15.Infection control & patient safety
Answer: B · The field is contaminated, because moisture can carry organisms through the drape
Why this is the answer
Liquid soaking through a drape can carry organisms up from the non-sterile surface below. The field is considered contaminated and is set up again.
Answer
B · The field is contaminated, because moisture can carry organisms through the drape
16.Infection control & patient safety
Answer: D · Temperature 38.6 °C and heart rate 112/min
Why this is the answer
SIRS criteria include a temperature above 38 °C or below 36 °C, heart rate above 90/min, respiratory rate above 20/min and a WBC above 12,000 or below 4,000/mm3. Only the first patient meets two.
Answer
D · Temperature 38.6 °C and heart rate 112/min
17.Lab values & electrolytes
Answer: C · Nystagmus, unsteady gait and slurred speech
Why this is the answer
Phenytoin toxicity causes nystagmus, ataxia, slurred speech and drowsiness. The nurse holds the dose and informs the prescriber. Low albumin increases the free (active) drug, so toxicity can occur even with a normal total level.
Answer
C · Nystagmus, unsteady gait and slurred speech
18.Lab values & electrolytes
Answer: C · Myoglobin from damaged muscle is in the urine
Why this is the answer
The dipstick blood test detects heme, which is present in both hemoglobin and myoglobin. Positive "blood" without red cells, together with a very high CK, indicates myoglobinuria from rhabdomyolysis, which can damage the kidneys. IV fluids and close monitoring of urine output and potassium are needed.Checked against:Myoglobin urine test · MedlinePlus (NIH) (2025); Rhabdomyolysis · MedlinePlus (NIH) (2025); Creatine Kinase · MedlinePlus (NIH) (2023)