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
How is a pulse deficit measured?
AOne nurse counts the apical pulse for 15 seconds and multiplies by four
BTwo nurses count the apical and radial pulse at the same time for one minute
CThe pulse oximeter rate is compared with the blood pressure reading
DOne nurse counts the radial pulse twice and compares the two counts
2.Nursing fundamentalsHard
A patient with dementia keeps getting out of bed at night. What is the best first nursing approach?
ALook for an unmet need such as toileting, pain, hunger or thirst
BAsk the doctor to prescribe a sedative so the patient sleeps through the night
CTie a sheet across the bed to keep the patient in
DRaise the bed rails and leave the patient alone
3.Clinical nursingMedium
When a patient returns to the ward from theatre, what should the nurse assess first?
AWhether visitors are waiting to see the patient
BThe discharge date
CThe patient's dietary preferences for the next meal
DAirway, breathing, circulation and level of consciousness
4.Clinical nursingHard
A patient with a head injury has a GCS that falls from 14 to 10 and one pupil becomes larger and slow to react. What should the nurse do?
AGive a sedative to calm the patient
BEscalate immediately as a neurological emergency
CRecheck the GCS at the next routine observation round
DEncourage the patient to sleep
5.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 75 mmHg (10.0 kPa). Use the rule that in acute respiratory acidosis HCO₃⁻ rises by 1 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
At sea level, a practice gas taken on 21% oxygen shows PaO₂ 93 mmHg (12.4 kPa) and PaCO₂ 40 mmHg (5.3 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.
Practice exercise (made-up values, not clinical guidance). A practice patient is assessed with the Braden scale: sensory perception: completely limited; moisture: rarely moist; activity: chairfast; mobility: slightly limited; nutrition: probably inadequate; friction and shear: problem. Find the Braden total B.
6–23
B =
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). The team aims for a mean arterial pressure of at least 65 mmHg. A patient’s systolic pressure is 115 mmHg. Using MAP = (SBP + 2·DBP)/3, what is the lowest diastolic pressure DBP that still gives a MAP of 65 mmHg?
Practice exercise (made-up values, not clinical guidance). A 93 kg adult (BMI below 30) needs 30 kcal/kg/day. The tube feed provides 2 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). Over 24 hours a patient receives 1800 mL of parenteral nutrition with final concentrations of 25% dextrose and 6% amino acids, plus 100 mL of 20% lipid emulsion (2 kcal/mL). Find the non-protein kilocalorie to nitrogen ratio NPC : N (the number x in x : 1). Round to the nearest whole number.
1800 mLdextrose 25%amino acids 6%lipid 100 mL · 2 kcal/mL
NPC : N =
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. Which interpretation can you defend from this single 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
12:1 AV block (type undetermined)
2second-degree AV block type I (Wenckebach)
3second-degree AV block type II
4first-degree AV block
13.Prioritization & delegationMedium
Which task should the nurse delegate to a nursing assistant for a patient on fall precautions?
ATeaching the family how to prevent falls at home
BDeciding whether the bed alarm is still needed
CAssessing and recording the patient’s fall risk score each morning
DHelping the patient to the toilet every 2 hours as planned
14.Prioritization & delegationHard
A patient in acute mania paces constantly, has lost weight and will not sit down to eat. Which intervention is most helpful?
ALeave meals in the room and let the patient eat whenever and whatever they choose
BInsist that the patient sits at the table until the meal is finished
COffer high-calorie finger foods and drinks the patient can take while moving
DWait until the mania settles before worrying about nutrition
15.Infection control & patient safetyMedium
A nurse finds a used needle in a patient’s bed linen. What should the nurse do?
ALeave it where it is for the housekeeping staff to remove later in the day
BRecap it with two hands before throwing it away
CFold it into the linen and send it to the laundry
DPick it up by the hub or with forceps, put it in a sharps container and report it
16.Infection control & patient safetyHard
Who should mark the operative site before surgery?
AThe admitting clerk, using the information written on the consent form
BAny member of the operating room team after anesthesia starts
CThe patient, alone, using a marker pen at home on the night before surgery
DThe person who will perform the procedure, with the patient involved where possible
17.Lab values & electrolytesMedium
A pregnant woman's blood type is O Rh-negative, and her antibody screen (indirect Coombs test) is negative. What is usually offered at about 28 weeks?
AAn IV dose of vitamin K given for the fetus
BA transfusion of group O Rh-positive red cells
CAnti-D immunoglobulin (Rho(D) immune globulin)
DDaily oral iron and folic acid supplements only
18.Lab values & electrolytesHard
A patient in DKA is receiving IV fluids and insulin. The glucose has fallen to about 220 mg/dL (12.2 mmol/L), but the anion gap is still high. What change would the nurse expect?
AStop the IV fluids and start oral fluids only
BStop the insulin infusion because the glucose is near normal
CGive an IV bolus of sodium bicarbonate at once
DAdd dextrose to the IV fluids and continue the insulin
3Solutions
1.Nursing fundamentals
Answer: B · Two nurses count the apical and radial pulse at the same time for one minute
Why this is the answer
A pulse deficit is the apical rate minus the radial rate, counted at the same time over a full minute. It shows that some heartbeats are too weak to reach the wrist, as in atrial fibrillation.
Answer
B · Two nurses count the apical and radial pulse at the same time for one minute
2.Nursing fundamentals
Answer: A · Look for an unmet need such as toileting, pain, hunger or thirst
Why this is the answer
Restlessness in dementia often has a cause, such as needing the toilet, pain or being cold. Meeting the need is safer than restraint or sedation, which increase the risk of harm.
Answer
A · Look for an unmet need such as toileting, pain, hunger or thirst
3.Clinical nursing
Answer: D · Airway, breathing, circulation and level of consciousness
Why this is the answer
Early postoperative assessment checks the airway, breathing, oxygen saturation, circulation, consciousness, pain, wound and drains. This detects anaesthetic and surgical complications early.
Answer
D · Airway, breathing, circulation and level of consciousness
4.Clinical nursing
Answer: B · Escalate immediately as a neurological emergency
Why this is the answer
A falling GCS with a unilateral dilated pupil suggests rising intracranial pressure and possible brain herniation. Urgent medical review and imaging are needed.
Answer
B · Escalate immediately as a neurological emergency
5.Arterial blood gas interpretation
Answer: HCO₃⁻ = 27.5 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
|75 − 40| = 35 mmHg → 3.5 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 1·3.5 = 27.5 mmol/L
Answer
HCO₃⁻ = 27.5 mmol/L
6.Arterial blood gas interpretation
Answer: A–a gradient = 6.73 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.
Braden scale: six subscales for pressure-injury risk. Sensory perception, moisture, activity, mobility and nutrition score 1 to 4, from the worst level (1) to no problem (4); friction and shear scores 1 to 3. The total runs from 6 to 23, and a lower total means a higher risk. Common bands: 19–23 not at risk, 15–18 mild risk, 13–14 moderate risk, 10–12 high risk and 9 or below very high risk.
Score each subscale
sensory perception: completely limited → 1
moisture: rarely moist → 4
activity: chairfast → 2
mobility: slightly limited → 3
nutrition: probably inadequate → 2
friction and shear: problem → 1
Add
Braden total = 1 + 4 + 2 + 3 + 2 + 1 = 13
Answer
B = 13
8.Clinical assessment scores
Answer: DBP = 40 mmHg
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.
Rearrange
DBP = (3·MAP − SBP)/2
Substitute
DBP = (3·65 − 115)/2 = 80/2 = 40 mmHg
Answer
DBP = 40 mmHg
9.Enteral & parenteral nutrition calculations
Answer: R = 70 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 = 30·93 = 2790 kcal/day
Daily volume
V = 2790/2 = 1395 mL/day
Pump rate
R = 1395/20 = 69.75 ≈ 70 mL/h
Answer
R = 70 mL/h
10.Enteral & parenteral nutrition calculations
Answer: NPC : N = 100
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.
Grams of dextrose and amino acids
dextrose: 25·1800/100 = 450 g
amino acids: 6·1800/100 = 108 g
Kilocalories per component
dextrose: 450·3.4 = 1530 kcal
amino acids: 108·4 = 432 kcal
lipid: 100·2 = 200 kcal
Non-protein kcal and nitrogen
NPC = 1530 + 200 = 1730 kcal
N = 108/6.25 = 17.28 g
Ratio
NPC : N = 1730/17.28 = 100.1 ≈ 100 : 1
Answer
NPC : N = 100
Ratios of about 150 : 1 are typical for stable patients; lower ratios give relatively more protein.
11.ECG rhythm strip interpretation
Answer: pause = 1.8 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
45 small boxes from R to R across the pause
Convert
pause = 45 × 0.04 s = 1.8 s
Compare with P–P
1.80 ÷ 0.76 ≈ 2.4 P–P cycles, not a whole number
Answer
pause = 1.8 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: 2:1 AV block (type undetermined)
2:1 AV block: with two P waves for every QRS, no two conducted P waves follow each other, so you cannot see whether the PR would lengthen (type I) or stay constant (type II) before a non-conducted P wave. From one strip it is called a 2:1 AV block; a longer strip or a change in the conduction ratio decides the type. A narrow QRS makes type I more likely and a wide QRS type II, but neither proves it.
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: upright and regular (P–P 0.72 s, 83 per minute), two for every QRS.
4. PR interval: constant at 0.18 s in the conducted beats.
5. QRS: 0.12 s, wide (0.12 s or more).
Why the type stays open
Every second P wave is not conducted, so no two conducted beats follow each other and a lengthening PR could never show.
2:1 AV block (type undetermined)
Answer
2:1 AV block (type undetermined)
A narrow QRS makes type I more likely and a wide QRS type II, but only a longer strip or a change in the conduction ratio decides.
13.Prioritization & delegation
Answer: D · Helping the patient to the toilet every 2 hours as planned
Why this is the answer
A scheduled toileting round is a routine task that follows the care plan. Scoring fall risk, deciding on interventions and teaching need nursing judgement.
Answer
D · Helping the patient to the toilet every 2 hours as planned
14.Prioritization & delegation
Answer: C · Offer high-calorie finger foods and drinks the patient can take while moving
Why this is the answer
Patients in mania may be too active to sit and eat. Portable high-calorie foods and fluids help meet physiological needs, which are a priority.
Answer
C · Offer high-calorie finger foods and drinks the patient can take while moving
15.Infection control & patient safety
Answer: D · Pick it up by the hub or with forceps, put it in a sharps container and report it
Why this is the answer
A loose needle is a hazard to everyone who handles the linen. The nurse disposes of it safely without recapping, using an instrument if needed, and reports the incident so the cause can be addressed.
Answer
D · Pick it up by the hub or with forceps, put it in a sharps container and report it
16.Infection control & patient safety
Answer: D · The person who will perform the procedure, with the patient involved where possible
Why this is the answer
Under the Universal Protocol, the site is marked by the person performing the procedure, or an authorized delegate, ideally while the patient is awake and can confirm it. This helps prevent wrong-site surgery.
Answer
D · The person who will perform the procedure, with the patient involved where possible
17.Lab values & electrolytes
Answer: C · Anti-D immunoglobulin (Rho(D) immune globulin)
Why this is the answer
An Rh-negative mother can form anti-D antibodies if Rh-positive fetal blood enters her circulation, which can cause hemolytic disease in a later pregnancy. Anti-D immunoglobulin at about 28 weeks and after delivery of an Rh-positive baby prevents this sensitization.Checked against:Red Blood Cell Antibody Screen · MedlinePlus (NIH) (2025); Hemolytic disease of the newborn · MedlinePlus (NIH) (2025)
Answer
C · Anti-D immunoglobulin (Rho(D) immune globulin)
18.Lab values & electrolytes
Answer: D · Add dextrose to the IV fluids and continue the insulin
Why this is the answer
The glucose usually falls before the ketoacidosis resolves. Dextrose is added so insulin can continue, clearing ketones without causing hypoglycemia, until the anion gap closes. Stopping insulin too early lets ketoacidosis return.
Answer
D · Add dextrose to the IV fluids and continue the insulin