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.
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.
2Practice problems
1.Med-surg: cardiovascular & respiratoryMedium
How can a patient reduce wound pain when coughing after abdominal surgery?
AAvoid coughing completely until all the stitches are removed
BHold a pillow firmly against the wound while coughing
CLie flat on the back with the legs straight
DHold the breath for as long as possible
2.Med-surg: cardiovascular & respiratoryHard
An older ex-smoker has a dry cough and worsening breathlessness over a year, finger clubbing and fine "Velcro-like" crackles at both bases at the end of inspiration. Which condition is most likely?
ACommunity-acquired pneumonia
BSpontaneous pneumothorax
CAn acute asthma attack
DIdiopathic pulmonary fibrosis
3.Med-surg: neuro, endocrine & renalMedium
Where is the zero point of an external ventricular drain usually levelled?
AAt the top of the head
BAt the tragus of the ear
CAt the level of the umbilicus
DAt the mid-axillary line of the chest
4.Med-surg: neuro, endocrine & renalHard
A patient with type 1 diabetes has a seizure on the ward. Their capillary glucose is 1.9 mmol/L (34 mg/dL). They cannot swallow. What is the most appropriate treatment?
AGlucose gel squeezed into the mouth during the seizure
BIV glucose or IM glucagon, then recheck the glucose
CAn antiepileptic drug only, because seizures need seizure treatment
DA rapid-acting insulin dose to stabilise the glucose
5.Med-surg: GI, perioperative & oncologyMedium
Which statement about giving medicines through a feeding tube is correct?
ATubes do not need flushing between medicines
BAll tablets can be crushed together and given at once
CModified-release tablets should not be crushed
DMedicines can be added to the bag of feed
6.Med-surg: GI, perioperative & oncologyHard
A patient is splashed in the eye with an alkaline cleaning product. What is the first action?
ACover the eye with a pad and wait for a doctor to examine it first
BAdd a few drops of vinegar to neutralise it
CAsk the patient to rub the eye to clear it
DIrrigate the eye at once with large volumes of water or saline
7.Clinical nursingMedium
What does HbA1c measure?
AInsulin levels after a meal
BAverage blood glucose over roughly the previous two to three months
CBlood glucose at the moment of testing
DThe amount of ketones in the urine
8.Clinical nursingHard
A patient with an acute GI bleed has a heart rate of 120/min and blood pressure 90/60 mmHg. What is the nursing priority after calling for help?
ADelay action until the stool colour is checked
BSecure large-bore IV access and prepare for fluid or blood replacement
CEncourage walking to the bathroom alone
DGive a large meal to restore energy
9.Lab values & electrolytesMedium
A patient taking furosemide has a potassium of 3.3 mEq/L and is told to eat more potassium-rich foods. Which snack is the best choice?
AWhite bread
BPlain crackers
CRice cakes
DDried apricots
10.Lab values & electrolytesHard
A patient with a new deep vein thrombosis is on a heparin infusion, and warfarin has just been started. Why is the heparin continued for several days?
AWarfarin only works when heparin is given at the same time
BHeparin prevents the side effects of warfarin
CHeparin increases the absorption of warfarin from the gut
DWarfarin takes several days to reach its full anticoagulant effect
11.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 76 mmHg (10.1 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⁻.
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
14.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 I (Wenckebach)
2second-degree AV block type II
3sinus bradycardia
4third-degree (complete) AV block
15.Prioritization & delegationMedium
A nurse asks a nursing assistant to use a mechanical lift. The assistant says they have never been trained to use it. Which right of delegation would be violated if the nurse insisted?
ARight person
BRight directions and communication
CRight supervision and evaluation
DRight task
16.Prioritization & delegationHard
Two patients on the unit have the same surname. What should the nurse do before giving a medication?
AAsk the patient, “Are you Mr Smith?” and give the drug once he says yes
BCheck two identifiers against the wristband and the medication record
CUse the room number as the main identifier
DAsk a nursing assistant which patient is which
3Solutions
1.Med-surg: cardiovascular & respiratory
Answer: B · Hold a pillow firmly against the wound while coughing
Why this is the answer
Splinting the incision with a pillow or folded towel supports the wound, reduces pain and makes effective coughing easier. Combined with good analgesia and deep breathing, this helps clear secretions and prevents atelectasis and pneumonia.
Answer
B · Hold a pillow firmly against the wound while coughing
2.Med-surg: cardiovascular & respiratory
Answer: D · Idiopathic pulmonary fibrosis
Why this is the answer
Idiopathic pulmonary fibrosis causes progressive breathlessness, a dry cough, clubbing and fine end-inspiratory crackles. Spirometry shows a restrictive pattern and CT shows fibrosis. Treatment includes antifibrotic drugs, pulmonary rehabilitation, oxygen and palliative care.
Answer
D · Idiopathic pulmonary fibrosis
3.Med-surg: neuro, endocrine & renal
Answer: B · At the tragus of the ear
Why this is the answer
The EVD is levelled at the tragus, which approximates the foramen of Monro. If the head of the bed is changed, the drain must be re-levelled, because its height decides how much CSF drains.
Answer
B · At the tragus of the ear
4.Med-surg: neuro, endocrine & renal
Answer: B · IV glucose or IM glucagon, then recheck the glucose
Why this is the answer
Severe hypoglycaemia can cause seizures. A patient who cannot swallow needs IV glucose, or IM glucagon if there is no IV access. Nothing should be put in the mouth of a fitting or unconscious patient. Glucose is rechecked and a long-acting carbohydrate is given when safe.
Answer
B · IV glucose or IM glucagon, then recheck the glucose
5.Med-surg: GI, perioperative & oncology
Answer: C · Modified-release tablets should not be crushed
Why this is the answer
Crushing modified-release or enteric-coated tablets can cause toxicity or loss of effect. Liquid forms are preferred; each medicine is given separately with flushes, and a pharmacist advises.
Answer
C · Modified-release tablets should not be crushed
6.Med-surg: GI, perioperative & oncology
Answer: D · Irrigate the eye at once with large volumes of water or saline
Why this is the answer
Alkali burns can cause severe, deep eye damage. Immediate, prolonged irrigation, checking the pH, and urgent ophthalmology review are needed. Neutralising agents are not used.
Answer
D · Irrigate the eye at once with large volumes of water or saline
7.Clinical nursing
Answer: B · Average blood glucose over roughly the previous two to three months
Why this is the answer
HbA1c reflects glycation of haemoglobin over the life of red cells, giving an estimate of long-term glucose control.
Answer
B · Average blood glucose over roughly the previous two to three months
8.Clinical nursing
Answer: B · Secure large-bore IV access and prepare for fluid or blood replacement
Why this is the answer
Tachycardia and hypotension suggest significant blood loss. ABCDE assessment, wide-bore IV access, bloods including cross-match and resuscitation come first, followed by endoscopy.
Answer
B · Secure large-bore IV access and prepare for fluid or blood replacement
9.Lab values & electrolytes
Answer: D · Dried apricots
Why this is the answer
Dried fruits such as apricots, raisins and prunes are rich in potassium, as are bananas, oranges, potatoes, beans and tomatoes. Refined grain products such as white bread and crackers are low in potassium.Checked against:Potassium in diet · MedlinePlus (NIH) (2026)
Answer
D · Dried apricots
10.Lab values & electrolytes
Answer: D · Warfarin takes several days to reach its full anticoagulant effect
Why this is the answer
Warfarin blocks the making of new vitamin K–dependent clotting factors, but existing factors last for days. Heparin is therefore overlapped until the INR has been in the target range, typically for at least 24 hours and after a minimum of about 5 days.
Answer
D · Warfarin takes several days to reach its full anticoagulant effect
11.Arterial blood gas interpretation
Answer: HCO₃⁻ = 36.6 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
|76 − 40| = 36 mmHg → 3.6 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 3.5·3.6 = 36.6 mmol/L
Answer
HCO₃⁻ = 36.6 mmol/L
12.Arterial blood gas interpretation
Answer: AGc = 15.25 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 = 134 − (110 + 11) = 13
Correction for albumin
13 + 0.25·(40 − 31) = 15.25 mmol/L
Answer
AGc = 15.25 mmol/L
Above about 12 after correction: a high anion gap.
13.ECG rhythm strip interpretation
Answer: pause = 2 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
50 small boxes from R to R across the pause
Convert
pause = 50 × 0.04 s = 2 s
Compare with P–P
2.00 ÷ 0.88 ≈ 2.3 P–P cycles, not a whole number
Answer
pause = 2 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.
14.ECG rhythm strip interpretation
Answer: second-degree AV block type II
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: 4 QRS complexes in 6 s, × 10 = 40 per minute.
2. Rhythm: the P waves are regular; R–R is regular except for a long pause where a QRS is missing.
3. P waves: upright and regular (P–P 0.96 s, 63 per minute); one P in every 3 is not followed by a QRS.
4. PR interval: constant at 0.16 s in the conducted beats.
5. QRS: 0.14 s, wide (0.12 s or more).
Interpretation
second-degree AV block type II
Answer
second-degree AV block type II
Type II and third-degree blocks are the ones that can suddenly progress, so textbooks rank them as more serious than type I.
15.Prioritization & delegation
Answer: A · Right person
Why this is the answer
Right person means the delegate has the training and competence for the task. Using a lift is normally a delegable task, but not to someone who has not been trained. The nurse should arrange training or do the task with help.
Answer
A · Right person
16.Prioritization & delegation
Answer: B · Check two identifiers against the wristband and the medication record
Why this is the answer
The nurse uses at least two identifiers, such as full name and date of birth, checked against the wristband and record. Open questions (“Please tell me your name”) are safer than yes/no questions.
Answer
B · Check two identifiers against the wristband and the medication record