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 cannot stand to be measured for the MUST screening tool. How can their height be estimated?
AFrom the length of the bed
BFrom the size of the patient's shoes
CBy asking a visitor to guess
DFrom the length of the forearm (ulna)
2.Nursing fundamentalsHard
A pressure ulcer's base is completely covered with slough and dark eschar. How is it classified?
ACategory 2, because it is covered
BCategory 1, because the skin is not open
CUnstageable, because the depth cannot be seen
DHealed, because a scab has formed
3.Clinical nursingMedium
A patient with leukaemia has a very low platelet count. Which nursing precaution is appropriate?
AEncourage contact sports to keep fit
BTake temperatures rectally
CGive medicines by intramuscular injection
DUse a soft toothbrush and an electric razor
4.Clinical nursingHard
A patient who has had a kidney stone is taught about prevention. Which statement shows a need for further teaching?
A"I will follow the diet advice for my stone type."
B"I will drink less water so I don't need to pass urine as often."
C"I will try to pass pale urine."
D"I will aim to drink plenty of fluids spread through every day."
5.Arterial blood gas interpretationMedium
Practice values: Na⁺ 149 mmol/L, glucose 11 mmol/L and urea 21.4 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 149 mmol/Lglucose 11 mmol/Lurea 21.4 mmol/L
Osm = mOsm/kg
6.Arterial blood gas interpretationHard
Practice values: Na⁺ 139, Cl⁻ 94 and HCO₃⁻ 13 mmol/L. Calculate the delta ratio (AG − 12)/(24 − HCO₃⁻), using AG = Na⁺ − (Cl⁻ + HCO₃⁻). Give two decimals.
Na⁺ 139 mmol/LCl⁻ 94 mmol/LHCO₃⁻ 13 mmol/L
delta ratio =
7.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). A practice patient after a head injury opens the eyes only to pressure (a painful stimulus), says inappropriate, random words and shows as the best motor response: extension of the arms and legs (abnormal extension). Work out the GCS and classify the head injury by it. Click your answer.
1mild
2moderate
3severe
8.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 12/min, SpO₂ 89% on room air, blood pressure 142/86 mmHg, pulse 82/min, alert, temperature 37.0 °C. Which clinical risk group does the patient fall into? Click it.
Practice exercise (made-up values, not clinical guidance). Use the Devine formula to find the ideal body weight IBW of a man who is 181 cm tall (1 in = 2.54 cm). Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A critically ill man is 173 cm tall and weighs 105 kg. The practice protocol gives 2 g of protein per kg of ideal body weight (Devine) per day if the BMI is 30 to under 40 kg/m², and 2.5 g/kg of ideal body weight per day if the BMI is 40 kg/m² or more. Find the protein goal P in g/day. Round to the nearest whole number.
This lead II strip shows atrial flutter. Measure the flutter-wave interval and find the atrial rate in beats per minute.
lead II, 25 mm/s, 10 mm/mV1 small box = 0.04 s, 1 large box = 0.20 sstrip length 6 s
atrial rate = bpm
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)
2first-degree AV block
3second-degree AV block type II
4third-degree (complete) AV block
13.Prioritization & delegationMedium
Four hours after thyroid surgery, which patient finding should the nurse act on first?
AA small amount of serous drainage visible on the neck dressing
BPain at the incision of 4/10
CA voice that is getting hoarser, with new noisy breathing
DA request to sit up to drink
14.Prioritization & delegationHard
Six hours after surgery, a patient has not passed urine, feels the urge to go and has a firm swelling above the pubic bone. What is the most likely problem?
AA normal effect of the anesthetic
BAcute kidney injury with no urine made
CUrinary retention
DDehydration from fasting before surgery
15.Infection control & patient safetyMedium
How is a urine specimen for culture obtained from an indwelling catheter?
ABy removing the catheter and sending its tip for culture
BBy disconnecting the catheter from the drainage tubing
CFrom the sampling port, after cleaning it, using aseptic technique
DFrom the urine already collected in the drainage bag at the bedside
16.Infection control & patient safetyHard
A nurse often skips barcode scanning to save time, as many colleagues do. In a just culture, how is this behavior classed?
ASimple human error, managed only by consoling the nurse and moving on
BAcceptable behavior, because it is common on the unit
CReckless behavior, managed by immediate dismissal and reporting to the licensing board
DAt-risk behavior, managed by coaching and fixing the system pressures behind it
17.Lab values & electrolytesMedium
A patient on warfarin for atrial fibrillation has a target INR of 2.0–3.0. How does the usual target for a patient with a mechanical mitral valve compare?
ALower, about 1.0–1.5
BHigher, about 2.5–3.5
CThe same, 2.0–3.0
DMuch higher, about 5.0–6.0
18.Lab values & electrolytesHard
A patient on clozapine for 2 years has been stable. Which statement shows a need for further teaching?
A"I can stop my blood tests since I feel well"
B"I'll report a sore throat or fever at once"
C"I'll keep all my scheduled blood test visits"
D"I'll tell other doctors that I take clozapine"
3Solutions
1.Nursing fundamentals
Answer: D · From the length of the forearm (ulna)
Why this is the answer
MUST includes tables that estimate height from ulna length when the patient cannot stand. Self-reported height can also be used if it is reliable.
Answer
D · From the length of the forearm (ulna)
2.Nursing fundamentals
Answer: C · Unstageable, because the depth cannot be seen
Why this is the answer
When slough or eschar hides the wound base, the true depth is unknown, so the ulcer is recorded as unstageable until the base can be seen.
Answer
C · Unstageable, because the depth cannot be seen
3.Clinical nursing
Answer: D · Use a soft toothbrush and an electric razor
Why this is the answer
Thrombocytopenia increases bleeding risk. Gentle oral care, electric razors and avoiding IM injections and rectal procedures help prevent bleeding.
Answer
D · Use a soft toothbrush and an electric razor
4.Clinical nursing
Answer: B · "I will drink less water so I don't need to pass urine as often."
Why this is the answer
A high fluid intake dilutes urine and is the most important general measure to prevent stones. Dietary advice depends on the stone's composition.
Answer
B · "I will drink less water so I don't need to pass urine as often."
5.Arterial blood gas interpretation
Answer: Osm = 330 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 = 2·149 + 11 + 21.4 = 330.4 ≈ 330 mOsm/kg
Answer
Osm = 330 mOsm/kg
6.Arterial blood gas interpretation
Answer: delta ratio = 1.818
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 = 139 − (94 + 13) = 32
Delta ratio
(32 − 12)/(24 − 13) = 20/11 = 1.818
Answer
delta ratio = 1.818
Between 1 and 2: a pure high anion gap acidosis.
7.Clinical assessment scores
Answer: severe
Glasgow Coma Scale: add the best response in three areas. Eye opening E: 4 spontaneous, 3 to sound or speech, 2 to pressure, 1 none. Verbal V: 5 oriented, 4 confused, 3 inappropriate words, 2 incomprehensible sounds, 1 none. Motor M: 6 obeys commands, 5 localises, 4 normal flexion (withdraws), 3 abnormal flexion, 2 extension, 1 none. The total runs from 3 to 15. After a head injury, 13–15 is usually called mild, 9–12 moderate and 3–8 severe.
Score each area
E: opens the eyes only to pressure (a painful stimulus) → 2
V: says inappropriate, random words → 3
M: extension of the arms and legs (abnormal extension) → 2
Add
GCS = 2 + 3 + 2 = 7
Severity
GCS 7 → severe
Answer
severe
8.Clinical assessment scores
Answer: low–medium
NEWS2 (National Early Warning Score 2, Royal College of Physicians 2017): score each of the seven parameters with the chart (respiration rate, SpO₂ on scale 1, air or supplemental oxygen, systolic blood pressure, pulse, consciousness on the ACVPU scale and temperature) and add the scores. Clinical risk: 0–4 low; a score of 3 in any single parameter low–medium; 5–6 medium; 7 or more high. A total of 5 or more needs an urgent response.
Score each parameter
RR 12/min → 0
SpO₂ 89% → 3
on air → 0
SBP 142 mmHg → 0
HR 82/min → 0
alert (A) → 0
T 37.0 °C → 0
Total and red scores
NEWS2 = 0 + 3 + 0 + 0 + 0 + 0 + 0 = 3
At least one parameter scores 3.
Risk group
low–medium
Answer
low–medium
A single score of 3 needs an urgent review even when the total is low.
9.Enteral & parenteral nutrition calculations
Answer: IBW = 75.9 kg
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.
Height in inches
181 cm/2.54 = 71.26 in
Ideal body weight (Devine)
IBW = 50 + 2.3·(71.26 − 60) = 75.9 kg
Answer
IBW = 75.9 kg
10.Enteral & parenteral nutrition calculations
Answer: P = 137 g/day
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. Obesity in critical illness (ASPEN/SCCM 2016): BMI = weight/height² (kg/m²). The protein goal is 2 g/kg of ideal body weight per day for BMI 30–40 and up to 2.5 g/kg of ideal body weight per day for BMI 40 and above. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.
Body mass index
BMI = 105/1.73² = 35.08 kg/m²
Ideal body weight (Devine)
173 cm/2.54 = 68.11 in
IBW = 50 + 2.3·(68.11 − 60) = 68.65 kg
Protein goal
BMI 30 to under 40: 2 g per kg of ideal body weight.
P = 2·68.65 = 137.3 ≈ 137 g/day
Answer
P = 137 g/day
11.ECG rhythm strip interpretation
Answer: atrial rate = 250 bpm
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.
Flutter waves
F–F = 6 small boxes = 0.24 s → 1500 ÷ 6 = 250 per minute
QRS complexes
R–R = 24 small boxes = 0.96 s → 1500 ÷ 24 = 63 per minute
conduction ratio = 250 ÷ 63 = 4:1
Answer
atrial rate = 250 bpm
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 = 42 small boxes, 1500 ÷ 42 ≈ 36 per minute.
2. Rhythm: regular, every R–R is 1.68 s.
3. P waves: upright and regular (P–P 0.84 s, 71 per minute), two for every QRS.
4. PR interval: constant at 0.18 s in the conducted beats.
5. QRS: 0.08 s, narrow (below 0.12 s).
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: C · A voice that is getting hoarser, with new noisy breathing
Why this is the answer
Increasing hoarseness and noisy breathing can mean swelling, bleeding or nerve injury affecting the airway. This must be assessed at once and escalated. Mild pain and a small amount of serous drainage are expected.
Answer
C · A voice that is getting hoarser, with new noisy breathing
14.Prioritization & delegation
Answer: C · Urinary retention
Why this is the answer
An urge to void with a palpable bladder points to retention, not reduced urine production. The nurse confirms with a bladder scan if available and follows the prescribed plan, such as catheterization.
Answer
C · Urinary retention
15.Infection control & patient safety
Answer: C · From the sampling port, after cleaning it, using aseptic technique
Why this is the answer
Urine in the bag is old and may contain extra bacteria, and disconnecting the system lets organisms in. The sample is taken from the sampling port with a sterile syringe after disinfecting the port.
Answer
C · From the sampling port, after cleaning it, using aseptic technique
16.Infection control & patient safety
Answer: D · At-risk behavior, managed by coaching and fixing the system pressures behind it
Why this is the answer
At-risk behavior is a choice whose risk is not recognized or is believed to be justified, often because shortcuts have become normal. It is managed by coaching and removing the pressures behind it, while reckless behavior may need disciplinary action.
Answer
D · At-risk behavior, managed by coaching and fixing the system pressures behind it
17.Lab values & electrolytes
Answer: B · Higher, about 2.5–3.5
Why this is the answer
Mechanical heart valves, especially in the mitral position, have a high risk of thrombosis, so the INR target is usually higher, about 2.5–3.5. An INR of 5 or more carries a high bleeding risk.Checked against:Label: WARFARIN SODIUM tablet · DailyMed (NLM/FDA) (2012)
Answer
B · Higher, about 2.5–3.5
18.Lab values & electrolytes
Answer: A · "I can stop my blood tests since I feel well"
Why this is the answer
Clozapine requires ongoing ANC monitoring according to the schedule, because severe neutropenia can occur without warning. The patient must keep blood test appointments and report signs of infection at once.