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.
Nursing math & unit conversions
Metric steps
1 kg = 1000 g, 1 g = 1000 mg, 1 mg = 1000 mcg, 1 L = 1000 mL
Weight and length
1 kg = 2.2 lb, 1 lb = 16 oz, 1 in = 2.54 cm, 1 ft = 12 in
Household measures
1 tsp = 5 mL, 1 tbsp = 15 mL, 1 fl oz = 30 mL, 1 cup = 8 fl oz = 240 mL
Write the given quantity with its unit and the unit you want.
Pick the equivalent: 1000 between kg, g, mg and mcg or L and mL; 1 kg = 2.2 lb; 1 tsp = 5 mL, 1 tbsp = 15 mL, 1 fl oz = 30 mL, 1 cup = 240 mL.
Write it as a fraction so that the unwanted unit cancels; for a rate, use one fraction per unit that changes.
Check the direction: a smaller unit gives a bigger number.
Round only the final answer, to the precision the question names.
2Practice problems
1.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 11/min, SpO₂ 98% on room air, blood pressure 130/78 mmHg, pulse 120/min, alert, temperature 36.2 °C. What is the NEWS2 total score?
RR 11SpO₂ 98%airSBP 130HR 120AT 36.2 °C
NEWS2 =
2.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 18/min, SpO₂ 96% on supplemental oxygen, blood pressure 118/70 mmHg, pulse 64/min, alert, temperature 38.8 °C. Which clinical risk group does the patient fall into? Click it.
RR 18SpO₂ 96%O₂SBP 118HR 64AT 38.8 °C
1low
2low–medium
3medium
4high
3.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 22 mmHg (2.9 kPa). Use the rule that in acute respiratory alkalosis HCO₃⁻ falls by 2 mmol/L for every 10 mmHg that PaCO₂ is below 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
A practice gas shows a respiratory acidosis: pH 7.32, PaCO₂ 69 mmHg (9.2 kPa), HCO₃⁻ 34 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 7.32PaCO₂ 69 mmHg (9.2 kPa)HCO₃⁻ 34 mmol/L
1acute
2chronic
3acute on chronic
5.Nursing fundamentalsMedium
How should a rectal suppository be inserted?
AJust inside the anus, without passing the sphincter
BAfter the patient has stood up and bent forward
CPast the internal sphincter, against the rectal wall
DInto the middle of the stool in the rectum so it softens it
6.Nursing fundamentalsHard
A patient with COPD and a target saturation of 88–92% is on oxygen. Their SpO₂ is now 97%. What should the nurse do?
AReduce the oxygen to bring the saturation back into the target range
BIncrease the oxygen to keep the level high
CLeave it, because a higher saturation is always better for a patient with COPD
DRemove all oxygen and stop monitoring
7.Nursing math & unit conversionsMedium
Practice exercise (made-up values, not clinical guidance). A patient is 5 ft 9 in tall. Using 1 ft = 12 in and 1 in = 2.54 cm, find the height h in centimetres, to the nearest whole centimetre.
5 ft 9 in1 ft = 12 in1 in = 2.54 cm
h = cm
8.Nursing math & unit conversionsHard
Practice exercise (made-up values, not clinical guidance). An infusion starts at 23:15 and finishes at 02:45 the next morning (24-hour clock). How many minutes t did it run?
23:1502:45
t = min
3Solutions
1.Clinical assessment scores
Answer: NEWS2 = 3
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 11/min → 1
SpO₂ 98% → 0
on air → 0
SBP 130 mmHg → 0
HR 120/min → 2
alert (A) → 0
T 36.2 °C → 0
Add
NEWS2 = 1 + 0 + 0 + 0 + 2 + 0 + 0 = 3
Answer
NEWS2 = 3
2.Clinical assessment scores
Answer: low
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 18/min → 0
SpO₂ 96% → 0
on oxygen → 2
SBP 118 mmHg → 0
HR 64/min → 0
alert (A) → 0
T 38.8 °C → 1
Total and red scores
NEWS2 = 0 + 0 + 2 + 0 + 0 + 0 + 1 = 3
No parameter scores 3.
Risk group
low
Answer
low
3.Arterial blood gas interpretation
Answer: HCO₃⁻ = 20.4 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
|22 − 40| = 18 mmHg → 1.8 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 − 2·1.8 = 20.4 mmol/L
Answer
HCO₃⁻ = 20.4 mmol/L
4.Arterial blood gas interpretation
Answer: chronic
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 + 1·2.9 = 26.9 mmol/L
chronic: 24 + 3.5·2.9 = 34.15 mmol/L
Compare
measured: 34 mmol/L → chronic
Answer
chronic
5.Nursing fundamentals
Answer: C · Past the internal sphincter, against the rectal wall
Why this is the answer
The suppository is pushed past the internal anal sphincter and placed against the rectal wall, usually with the patient lying on the left side. Placing it in stool stops absorption.
Answer
C · Past the internal sphincter, against the rectal wall
6.Nursing fundamentals
Answer: A · Reduce the oxygen to bring the saturation back into the target range
Why this is the answer
For patients at risk of hypercapnia, saturations above the target can raise CO₂ levels. The oxygen should be reduced step by step to the prescribed range, with continued monitoring.
Answer
A · Reduce the oxygen to bring the saturation back into the target range
7.Nursing math & unit conversions
Answer: h = 175 cm
Household measures and weight: nursing exams use rounded equivalents: 1 teaspoon (tsp) = 5 mL, 1 tablespoon (tbsp) = 15 mL = 3 tsp, 1 fluid ounce (fl oz) = 30 mL = 2 tbsp, and 1 cup = 8 fl oz = 240 mL. For weight, 1 kg = 2.2 lb and 1 lb = 16 oz; for length, 1 inch = 2.54 cm. Set the conversion up so that the unit you do not want cancels out.
Height in inches
5·12 + 9 = 69 in
Inches to centimetres
h = 69·2.54 = 175.3 ≈ 175 cm
Answer
h = 175 cm
8.Nursing math & unit conversions
Answer: t = 210 min
24-hour clock: from 1 PM onwards add 12 to the hour (3:45 PM = 15:45). Midnight to 12:59 AM is 00:00–00:59, and 12:00–12:59 PM stays 12:00–12:59. Going back, subtract 12 from hours 13–23 and add PM; hours 00 become 12 AM. Count time across midnight in two parts: up to 24:00 (00:00), then from 00:00 on.