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
A patient stops ramipril because of a troublesome dry cough. Which drug class is a common alternative?
AA non-selective beta-blocker such as propranolol
BA loop diuretic such as furosemide
CAn angiotensin II receptor blocker such as losartan
DA nitrate such as isosorbide mononitrate
2.Med-surg: cardiovascular & respiratoryHard
After six weeks of treatment for tuberculosis, a patient has nausea, dark urine and yellow eyes. What should the nurse do?
AReassure the patient that the urine colour is due to rifampicin
BAdvise taking the tablets with an alcoholic drink to settle the stomach
CWithhold the next doses and report urgently for liver tests
DDouble the isoniazid dose to clear the infection faster
3.Med-surg: neuro, endocrine & renalMedium
A patient uses a continuous glucose monitor. Which statement is correct?
AIt works by giving small doses of insulin automatically
BIt makes finger-prick checks unnecessary in every situation
CIt measures glucose directly in the blood every second of the day
DIt reads glucose in fluid under the skin, a little behind blood glucose
4.Med-surg: neuro, endocrine & renalHard
Which statement correctly distinguishes spinal shock from neurogenic shock?
ASpinal shock is low blood pressure; neurogenic shock is the loss of reflexes
BSpinal shock is lost reflexes; neurogenic shock is low BP and slow pulse
CNeurogenic shock is caused by blood loss; spinal shock is caused by infection
DThey are two names for exactly the same condition
5.Med-surg: GI, perioperative & oncologyMedium
Which treatment often relieves pain from a bone metastasis?
AIron supplements by mouth for several months
BComplete bed rest for a month
CPalliative radiotherapy to the area
DA diet low in calcium and vitamin D
6.Med-surg: GI, perioperative & oncologyHard
On the ward after surgery, a patient has a red, blistered area of skin under where the diathermy plate was. What should the nurse do?
ATreat it as a possible burn, report it and complete an incident form
BWash it with alcohol and leave it uncovered
CIgnore it because skin changes after surgery are normal and expected to fade
DApply a hot water bottle to improve the circulation
7.Clinical nursingMedium
A patient with Guillain–Barré syndrome has weakness spreading upwards from the legs. Which monitoring is most important?
AVisual acuity
BWeekly weight
CBlood glucose, measured once a day before breakfast
DBreathing function, such as forced vital capacity
8.Clinical nursingHard
A day after surgery, a patient's haemoglobin has fallen from 125 g/L to 85 g/L (12.5 to 8.5 g/dL) and their heart rate has risen to 118/min. What is the priority?
ARecheck the haemoglobin next week
BEncourage the patient to eat iron-rich foods
CEscalate urgently, as the patient may be bleeding
DDocument the result and take no further action
9.Lab values & electrolytesMedium
A healthy woman at 28 weeks of pregnancy has a mildly lower hemoglobin than before pregnancy, with a normal MCV and ferritin. What is the most likely explanation?
APregnancy hormones stop the bone marrow from making red cells
BPlasma volume rises more than red cell mass, diluting the blood
CThe fetus is destroying the mother's red cells in the circulation
DIron is being lost through the kidneys during the pregnancy
10.Lab values & electrolytesHard
A patient’s vancomycin trough is 28 mcg/mL; the target set by the prescriber is 15–20 mcg/mL. The next dose is due now. What is the best action?
AGive the dose as scheduled and recheck the trough level in a week
BGive the dose over a shorter time to reduce exposure
CHold the dose, inform the prescriber and check kidney function
DGive a double dose to finish the course faster
11.Arterial blood gas interpretationMedium
Practice values: Na⁺ 143 mmol/L, glucose 28.5 mmol/L and urea 19.6 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 143 mmol/Lglucose 28.5 mmol/Lurea 19.6 mmol/L
Osm = mOsm/kg
12.Arterial blood gas interpretationHard
Practice values: Na⁺ 138, Cl⁻ 103, HCO₃⁻ 16 mmol/L and albumin 24 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).
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
2sinus rhythm with PVCs
3ventricular bigeminy
4sinus arrhythmia
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)
2first-degree AV block
3atrial fibrillation
4second-degree AV block type II
15.Prioritization & delegationMedium
During a blood transfusion, a patient develops chills, back pain and a fever. What is the nurse’s first action?
AGive an antipyretic and continue the transfusion
BStop the transfusion and keep the IV open with normal saline via new tubing
CFinish the unit quickly through a pressure bag so that the reaction does not last long
DSlow the transfusion and recheck in an hour
16.Prioritization & delegationHard
A patient on a cardiac monitor suddenly becomes unresponsive, and the monitor shows ventricular fibrillation. What is the priority once help has been called?
ACheck the blood potassium level before any shock is considered
BGive an oral antiarrhythmic tablet and recheck the rhythm in five minutes
CRecord a full 12-lead ECG to confirm the rhythm before doing anything else at all
DDefibrillate as soon as the defibrillator is available, with CPR until then
3Solutions
1.Med-surg: cardiovascular & respiratory
Answer: C · An angiotensin II receptor blocker such as losartan
Why this is the answer
Angiotensin receptor blockers (ending in -sartan) block the effects of angiotensin II without inhibiting ACE, so bradykinin does not build up and cough is much less common. They share other effects, such as raising potassium, and ACE inhibitors and ARBs are not normally combined.
Answer
C · An angiotensin II receptor blocker such as losartan
2.Med-surg: cardiovascular & respiratory
Answer: C · Withhold the next doses and report urgently for liver tests
Why this is the answer
Isoniazid, rifampicin and pyrazinamide can all cause hepatotoxicity. Jaundice, dark urine and nausea suggest drug-induced hepatitis, so the drugs are stopped and liver function is checked urgently. Orange urine from rifampicin does not cause yellow eyes. Alcohol increases the risk.
Answer
C · Withhold the next doses and report urgently for liver tests
3.Med-surg: neuro, endocrine & renal
Answer: D · It reads glucose in fluid under the skin, a little behind blood glucose
Why this is the answer
CGM sensors measure interstitial glucose, which lags several minutes behind blood glucose, especially when levels change fast. A finger-prick check is advised when symptoms do not match the reading.
Answer
D · It reads glucose in fluid under the skin, a little behind blood glucose
4.Med-surg: neuro, endocrine & renal
Answer: B · Spinal shock is lost reflexes; neurogenic shock is low BP and slow pulse
Why this is the answer
Spinal shock is the temporary loss of reflexes and tone below the injury. Neurogenic shock is hypotension and bradycardia caused by loss of sympathetic tone, usually with injuries at T6 or above. The two can occur together.
Answer
B · Spinal shock is lost reflexes; neurogenic shock is low BP and slow pulse
5.Med-surg: GI, perioperative & oncology
Answer: C · Palliative radiotherapy to the area
Why this is the answer
A single fraction or short course of radiotherapy relieves pain from bone metastases in many patients. Analgesia, including NSAIDs where suitable, and bone-targeted drugs are also used.
Answer
C · Palliative radiotherapy to the area
6.Med-surg: GI, perioperative & oncology
Answer: A · Treat it as a possible burn, report it and complete an incident form
Why this is the answer
A blister under the return electrode suggests a diathermy burn. The nurse assesses and dresses it, informs the team, and reports it as an incident so that the cause can be investigated.
Answer
A · Treat it as a possible burn, report it and complete an incident form
7.Clinical nursing
Answer: D · Breathing function, such as forced vital capacity
Why this is the answer
Guillain–Barré syndrome can paralyse the respiratory muscles. Serial vital capacity measurements help identify patients who need ventilation before they deteriorate.
Answer
D · Breathing function, such as forced vital capacity
8.Clinical nursing
Answer: C · Escalate urgently, as the patient may be bleeding
Why this is the answer
A large fall in haemoglobin with tachycardia suggests ongoing blood loss. The nurse assesses the patient with ABCDE, checks wounds and drains and escalates for urgent review.
Answer
C · Escalate urgently, as the patient may be bleeding
9.Lab values & electrolytes
Answer: B · Plasma volume rises more than red cell mass, diluting the blood
Why this is the answer
In pregnancy, plasma volume increases by more than red cell mass, so the hemoglobin falls slightly (physiologic or dilutional anemia). Iron deficiency is still common in pregnancy and is checked with the MCV and ferritin.Checked against:Anemia · StatPearls (NCBI Bookshelf) (2026)
Answer
B · Plasma volume rises more than red cell mass, diluting the blood
10.Lab values & electrolytes
Answer: C · Hold the dose, inform the prescriber and check kidney function
Why this is the answer
A trough above target means the drug is building up, which raises the risk of kidney damage. The nurse holds the dose and informs the prescriber, who will adjust the dose or interval. The kidney function is checked.
Answer
C · Hold the dose, inform the prescriber and check kidney function
11.Arterial blood gas interpretation
Answer: Osm = 334 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 = 2·143 + 28.5 + 19.6 = 334.1 ≈ 334 mOsm/kg
Answer
Osm = 334 mOsm/kg
12.Arterial blood gas interpretation
Answer: AGc = 23 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 = 138 − (103 + 16) = 19
Correction for albumin
19 + 0.25·(40 − 24) = 23 mmol/L
Answer
AGc = 23 mmol/L
Above about 12 after correction: a high anion gap.
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 (0.50 s and 1.26 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: 0.08 s in the sinus beats; the early beats are wide (0.14 s) and bizarre, with the T wave pointing the other way.
Interpretation
ventricular bigeminy
Answer
ventricular bigeminy
14.ECG rhythm strip interpretation
Answer: second-degree AV block type I (Wenckebach)
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: 5 QRS complexes in 6 s, × 10 = 50 per minute.
2. Rhythm: regularly irregular, the QRS complexes come in groups separated by a pause (group beating).
3. P waves: upright and regular (P–P 0.88 s, 68 per minute); one P in every 4 is not followed by a QRS.
4. PR interval: lengthens 0.18 → 0.30 → 0.38 s, then a P wave is not conducted.
5. QRS: 0.08 s, narrow (below 0.12 s).
Interpretation
second-degree AV block type I (Wenckebach)
Answer
second-degree AV block type I (Wenckebach)
15.Prioritization & delegation
Answer: B · Stop the transfusion and keep the IV open with normal saline via new tubing
Why this is the answer
For any suspected transfusion reaction, the nurse stops the transfusion at once, keeps the vein open with normal saline through new tubing and informs the provider and blood bank.
Answer
B · Stop the transfusion and keep the IV open with normal saline via new tubing
16.Prioritization & delegation
Answer: D · Defibrillate as soon as the defibrillator is available, with CPR until then
Why this is the answer
Ventricular fibrillation is a shockable cardiac arrest rhythm. Early defibrillation, with high-quality CPR until the shock is given, is the most important treatment.
Answer
D · Defibrillate as soon as the defibrillator is available, with CPR until then