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). A practice patient is assessed with the Braden scale: sensory perception: very limited; moisture: rarely moist; activity: bedfast; mobility: slightly limited; nutrition: very poor; friction and shear: potential problem. Find the Braden total B.
6–23
B =
2.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 16/min, SpO₂ 99% on supplemental oxygen, blood pressure 118/70 mmHg, pulse 58/min, alert, temperature 37.9 °C. Which clinical risk group does the patient fall into? Click it.
RR 16SpO₂ 99%O₂SBP 118HR 58AT 37.9 °C
1low
2low–medium
3medium
4high
3.Arterial blood gas interpretationMedium
A practice arterial blood gas shows pH 7.15, PaCO₂ 71 mmHg (9.5 kPa) and HCO₃⁻ 24 mmol/L. The primary disorder is respiratory acidosis. How far is it compensated? Click your answer.
pH 7.15PaCO₂ 71 mmHg (9.5 kPa)HCO₃⁻ 24 mmol/L
1uncompensated
2partially compensated
3fully compensated
4.Arterial blood gas interpretationHard
A practice gas shows pH 7.22, PaCO₂ 20 mmHg (2.7 kPa) and HCO₃⁻ 8 mmol/L, with Na⁺ 136 and Cl⁻ 108 mmol/L. Use the anion gap and the delta ratio to click the best interpretation.
A patient's blood pressure is much higher than in all previous readings. What is the best first step?
ATell the patient they are having a stroke
BRecheck it, making sure the technique and cuff size are correct
CIgnore it, as it must be a machine error
DRecord it and give an extra dose of the blood pressure tablet
6.Nursing fundamentalsHard
A nurse notices that the power cable of an infusion pump is frayed. What is the correct action?
AUse it only for patients who are not seriously ill
BTake it out of use, label it as faulty and report it
CUnplug it and put it back in the equipment store
DWrap tape around the cable and keep using it
7.Nursing math & unit conversionsMedium
Practice exercise (made-up values, not clinical guidance). A patient’s temperature is 37.6 °C. Convert it to degrees Fahrenheit T with °F = °C × 9/5 + 32. Round to one decimal place.
37.6 °C
T = °F
8.Nursing math & unit conversionsHard
Practice exercise (made-up values, not clinical guidance). A haemoglobin result is 94 g/L. Express it in g/dL Hb.
94 g/L1 L = 10 dL
Hb = g/dL
3Solutions
1.Clinical assessment scores
Answer: B = 13
Braden scale: six subscales for pressure-injury risk. Sensory perception, moisture, activity, mobility and nutrition score 1 to 4, from the worst level (1) to no problem (4); friction and shear scores 1 to 3. The total runs from 6 to 23, and a lower total means a higher risk. Common bands: 19–23 not at risk, 15–18 mild risk, 13–14 moderate risk, 10–12 high risk and 9 or below very high risk.
Score each subscale
sensory perception: very limited → 2
moisture: rarely moist → 4
activity: bedfast → 1
mobility: slightly limited → 3
nutrition: very poor → 1
friction and shear: potential problem → 2
Add
Braden total = 2 + 4 + 1 + 3 + 1 + 2 = 13
Answer
B = 13
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 16/min → 0
SpO₂ 99% → 0
on oxygen → 2
SBP 118 mmHg → 0
HR 58/min → 0
alert (A) → 0
T 37.9 °C → 0
Total and red scores
NEWS2 = 0 + 0 + 2 + 0 + 0 + 0 + 0 = 2
No parameter scores 3.
Risk group
low
Answer
low
3.Arterial blood gas interpretation
Answer: uncompensated
Reading a blood gas (ROME): first the pH: below 7.35 is acidaemia, above 7.45 alkalaemia. Then find the value that explains it. PaCO₂ (normal 35–45 mmHg, 4.7–6.0 kPa) is the respiratory part and moves Opposite to the pH in a respiratory disorder; HCO₃⁻ (normal 22–26 mmol/L) is the metabolic part and moves in the same direction as the pH (Respiratory Opposite, Metabolic Equal). The other value shows the compensation: normal means uncompensated; abnormal in the direction that pulls the pH back while the pH is still abnormal means partially compensated; a normal pH with both values abnormal means fully compensated. Ranges differ slightly between laboratories; these are practice values.
ROME, value by value
pH 7.15: acidaemia (below 7.35)
PaCO₂ 71 mmHg: high (35–45)
HCO₃⁻ 24 mmol/L: normal (22–26)
Compensation
uncompensated
Answer
uncompensated
4.Arterial blood gas interpretation
Answer: added normal-gap acidosis
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 = 136 − (108 + 8) = 20
Delta ratio
(20 − 12)/(24 − 8) = 0.5
added normal-gap acidosis
Answer
added normal-gap acidosis
5.Nursing fundamentals
Answer: B · Recheck it, making sure the technique and cuff size are correct
Why this is the answer
Unexpected findings are validated before action. If the repeat reading is still high, the nurse assesses for symptoms and reports it.
Answer
B · Recheck it, making sure the technique and cuff size are correct
6.Nursing fundamentals
Answer: B · Take it out of use, label it as faulty and report it
Why this is the answer
Damaged electrical equipment can cause shocks or fires. It is removed from use, clearly labelled and reported for repair, and a safe replacement is found.
Answer
B · Take it out of use, label it as faulty and report it
7.Nursing math & unit conversions
Answer: T = 99.7 °F
Temperature: °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32. Subtract 32 before you multiply when going from °F, and add 32 after you multiply when going from °C. A quick check: 37 °C is 98.6 °F, and every 1 °C is 1.8 °F.
Multiply by 9/5
37.6·9/5 = 67.68
Add 32
T = 67.68 + 32 = 99.68 ≈ 99.7 °F
Answer
T = 99.7 °F
8.Nursing math & unit conversions
Answer: Hb = 9.4 g/dL
Dimensional analysis: write the given quantity, then multiply by conversion factors written as fractions (for example 60 min/1 h or 1 mg/1000 mcg) so that each unwanted unit appears once on top and once underneath and cancels. When only the wanted unit is left, calculate. Use the equivalents the question gives and round only the final answer.