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
Which skin changes around the ankles are typical of chronic venous insufficiency?
APale, shiny, hairless skin with weak pulses
BA cold, white foot with no pulse
CBrown staining, swelling and dry, itchy skin
DA sharply defined red patch with fever
2.Med-surg: cardiovascular & respiratoryHard
A patient with asthma has a history of wheeze after taking aspirin. Ibuprofen is prescribed for postoperative pain. What should the nurse do?
AGive it, because ibuprofen is not related to aspirin
BGive it only if the pain score is above 8/10
CWithhold it and ask for an alternative
DGive it with the reliever inhaler at the same time
3.Med-surg: neuro, endocrine & renalMedium
A patient receives phenytoin through a nasogastric tube along with continuous enteral feed. Which issue should the nurse know about?
AThe feed increases phenytoin levels and causes toxicity within hours
BPhenytoin makes the feed curdle, so the two must never be used in one patient
CThe feed can reduce phenytoin absorption, so the feed is often paused around the dose
DPhenytoin must be crushed and mixed into the feed bag
4.Med-surg: neuro, endocrine & renalHard
A patient recovering from acute tubular necrosis enters the polyuric phase, passing over 4 L of urine a day. What is the main nursing concern?
AHypoglycaemia caused by excess insulin
BFluid overload with high potassium levels
CDehydration with low potassium and sodium
DRetention of urine in a distended bladder
5.Med-surg: GI, perioperative & oncologyMedium
Which finding suggests a deep tissue pressure injury?
AIntact skin that is purple or maroon over a bony area
BPale pink skin that blanches quickly when pressed
CA small scratch on the skin with a little fresh red blood
DDry, flaky skin on both shins
6.Med-surg: GI, perioperative & oncologyHard
A patient has had a large terminal ileum resection for Crohn's disease. Which long-term problems should the nurse anticipate?
AExcess vitamin D and calcium kidney stones in the first year
BIron overload and constipation
CInsulin deficiency and high blood glucose from loss of the islets
DVitamin B12 deficiency and bile-acid diarrhoea
7.Clinical nursingMedium
The WHO analgesic ladder recommends:
AGiving analgesia only when pain becomes severe
BStarting all patients on strong opioids
CMoving from non-opioids to weak and then strong opioids as pain increases
DUsing only non-drug methods for cancer pain
8.Clinical nursingHard
A patient with full mental capacity decides against a treatment that the team thinks is best. What does the Mental Capacity Act 2005 (England and Wales) say?
AThe team may override any decision that it disagrees with if it is serious
BThe patient must be assessed by a psychiatrist before refusing
CThe family may make the decision instead if they disagree with the patient's choice
DA person is not treated as lacking capacity just because they make an unwise decision
9.Lab values & electrolytesMedium
A trauma patient receives 2 L of IV crystalloid. The hemoglobin falls from 13.0 to 11.4 g/dL (130 to 114 g/L), and the vital signs are now stable. Which explanation is most likely?
AIncreased red cell production
BA laboratory error in the first sample
CA sudden failure of the bone marrow
DDilution of the blood by the IV fluid
10.Lab values & electrolytesHard
A patient on high-dose dexamethasone has a white cell count of 15 × 10³/µL, mostly mature neutrophils with no bands. They have no fever and no signs of infection. What is the most likely explanation?
AA laboratory error, because steroids always lower the white count
BCertain sepsis that needs antibiotics started without delay
CA steroid effect that moves neutrophils into the circulating blood
DA new leukemia that is confirmed by this result alone
11.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 64 mmHg (8.5 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⁻.
A practice gas shows a respiratory acidosis: pH 7.18, PaCO₂ 78 mmHg (10.4 kPa), HCO₃⁻ 28 mmol/L. Use the rules ‘HCO₃⁻ rises 1 mmol/L per 10 mmHg (acute) or 3.5 mmol/L per 10 mmHg (chronic)’ to classify it. Click your answer.
pH 7.18PaCO₂ 78 mmHg (10.4 kPa)HCO₃⁻ 28 mmol/L
1acute
2chronic
3acute on chronic
13.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
1normal sinus rhythm
2sinus rhythm with PVCs
3sinus arrhythmia
4ventricular bigeminy
14.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
1sinus rhythm with wide QRS
2dual-chamber (AV) paced rhythm
3paced rhythm, failure to capture
4idioventricular rhythm
15.Prioritization & delegationMedium
A charge nurse needs to free a bed. Which patient is most appropriate for discharge or transfer to a lower level of care?
ADay 3 after uncomplicated appendectomy, eating, on oral analgesia
BDay 1 after bowel surgery with a new temperature of 38.5 °C
CAdmitted two hours ago with chest pain; troponin result still pending
DPneumonia, with an oxygen need that rose overnight from 2 to 4 L/min
16.Prioritization & delegationHard
A patient arrives one hour after the start of stroke symptoms. Which step must happen before a thrombolytic drug can be given?
AA full lipid profile to check cholesterol
BA swallow test with a cup of water
CAn echocardiogram to look for clots
DA brain scan to rule out bleeding
3Solutions
1.Med-surg: cardiovascular & respiratory
Answer: C · Brown staining, swelling and dry, itchy skin
Why this is the answer
High venous pressure causes oedema and leakage of red cells, depositing haemosiderin (brown staining), with venous eczema and lipodermatosclerosis. Pale, shiny, hairless skin suggests arterial disease. Venous ulcers often form above the medial malleolus.
Answer
C · Brown staining, swelling and dry, itchy skin
2.Med-surg: cardiovascular & respiratory
Answer: C · Withhold it and ask for an alternative
Why this is the answer
In NSAID-exacerbated respiratory disease, aspirin and other COX-1 inhibiting NSAIDs can trigger severe bronchospasm. A patient with a history of reacting to aspirin should not receive other NSAIDs without specialist advice. Paracetamol at usual doses is generally tolerated.
Answer
C · Withhold it and ask for an alternative
3.Med-surg: neuro, endocrine & renal
Answer: C · The feed can reduce phenytoin absorption, so the feed is often paused around the dose
Why this is the answer
Enteral feeds can bind phenytoin and greatly reduce how much is absorbed. Local protocols usually pause the feed before and after the dose and flush the tube. Drug levels are monitored.
Answer
C · The feed can reduce phenytoin absorption, so the feed is often paused around the dose
4.Med-surg: neuro, endocrine & renal
Answer: C · Dehydration with low potassium and sodium
Why this is the answer
In the diuretic phase of ATN, filtration recovers before tubular reabsorption, so large volumes of dilute urine are passed. Patients risk hypovolaemia and losses of potassium and sodium. Fluid balance, daily weight and electrolytes are monitored and fluids replaced as prescribed.
Answer
C · Dehydration with low potassium and sodium
5.Med-surg: GI, perioperative & oncology
Answer: A · Intact skin that is purple or maroon over a bony area
Why this is the answer
A deep tissue injury appears as persistent purple, maroon or dark discolouration, or a blood-filled blister, from pressure and shear on underlying tissue. It may quickly turn into a deep wound.
Answer
A · Intact skin that is purple or maroon over a bony area
6.Med-surg: GI, perioperative & oncology
Answer: D · Vitamin B12 deficiency and bile-acid diarrhoea
Why this is the answer
The terminal ileum absorbs vitamin B12 and bile acids. After resection, B12 replacement may be needed, and unabsorbed bile acids reaching the colon cause diarrhoea.
Answer
D · Vitamin B12 deficiency and bile-acid diarrhoea
7.Clinical nursing
Answer: C · Moving from non-opioids to weak and then strong opioids as pain increases
Why this is the answer
The ladder moves from non-opioids (such as paracetamol) to weak opioids and then strong opioids, with adjuvants at any step. Regular dosing is preferred for persistent pain.
Answer
C · Moving from non-opioids to weak and then strong opioids as pain increases
8.Clinical nursing
Answer: D · A person is not treated as lacking capacity just because they make an unwise decision
Why this is the answer
One of the Act's principles is that making an unwise decision is not, on its own, evidence of incapacity. The team should check understanding, explore reasons and document the discussion.
Answer
D · A person is not treated as lacking capacity just because they make an unwise decision
9.Lab values & electrolytes
Answer: D · Dilution of the blood by the IV fluid
Why this is the answer
IV fluids dilute the blood, so the hemoglobin falls even without further bleeding. Ongoing bleeding must still be considered, so vital signs, wounds and repeat hemoglobin values are monitored.
Answer
D · Dilution of the blood by the IV fluid
10.Lab values & electrolytes
Answer: C · A steroid effect that moves neutrophils into the circulating blood
Why this is the answer
Corticosteroids raise the neutrophil count by releasing marginated neutrophils and slowing their exit from the blood, usually without a left shift. The nurse still assesses carefully, because steroids can also hide the usual signs of infection.
Answer
C · A steroid effect that moves neutrophils into the circulating blood
11.Arterial blood gas interpretation
Answer: HCO₃⁻ = 32.4 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
|64 − 40| = 24 mmHg → 2.4 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 3.5·2.4 = 32.4 mmol/L
Answer
HCO₃⁻ = 32.4 mmol/L
12.Arterial blood gas interpretation
Answer: acute
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.
Expected HCO₃⁻
acute: 24 + 1·3.8 = 27.8 mmol/L
chronic: 24 + 3.5·3.8 = 37.3 mmol/L
Compare
measured: 28 mmol/L → acute
Answer
acute
13.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: 7 QRS complexes in 6 s, × 10 = 70 per minute.
2. Rhythm: regularly irregular, a short and a long R–R alternate (0.52 s and 1.16 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: 0.10 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
14.ECG rhythm strip interpretation
Answer: dual-chamber (AV) paced rhythm
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: R–R = 25 small boxes, 1500 ÷ 25 ≈ 60 per minute.
2. Rhythm: regular, every R–R is 1.00 s.
3. P waves: each P wave follows its own pacing spike (atrial pacing).
4. AV interval: the second spike comes 0.18 s after the first one (the programmed AV delay).
5. QRS: 0.14 s, wide, right after the second spike (ventricular pacing).
Interpretation
dual-chamber (AV) paced rhythm
Answer
dual-chamber (AV) paced rhythm
The paced QRS is wide by nature; do not call it a bundle branch block or a ventricular rhythm.
15.Prioritization & delegation
Answer: A · Day 3 after uncomplicated appendectomy, eating, on oral analgesia
Why this is the answer
The appendectomy patient is stable, eating and managing with oral pain relief. A pending troponin, rising oxygen needs and a new fever all mean the patient’s course is not yet clear.
Answer
A · Day 3 after uncomplicated appendectomy, eating, on oral analgesia
16.Prioritization & delegation
Answer: D · A brain scan to rule out bleeding
Why this is the answer
Thrombolytics dissolve clots and would worsen a hemorrhagic stroke. A brain CT (or MRI) is needed first to rule out bleeding, and it must be done quickly.