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 chart records GCS 8, with E3 and V2. What motor score M was recorded, and which response does it describe? Give the number.
GCS 8E3V2
M =
2.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 14/min, SpO₂ 98% on room air, blood pressure 150/90 mmHg, pulse 58/min, alert, temperature 35.5 °C. Which clinical risk group does the patient fall into? Click it.
RR 14SpO₂ 98%airSBP 150HR 58AT 35.5 °C
1low
2low–medium
3medium
4high
3.Arterial blood gas interpretationMedium
A practice arterial blood gas shows pH 7.36, PaCO₂ 72 mmHg (9.6 kPa) and HCO₃⁻ 39 mmol/L. The primary disorder is respiratory acidosis. How far is it compensated? Click your answer.
pH 7.36PaCO₂ 72 mmHg (9.6 kPa)HCO₃⁻ 39 mmol/L
1uncompensated
2partially compensated
3fully compensated
4.Arterial blood gas interpretationHard
A practice gas shows a metabolic acidosis: pH 7.08, PaCO₂ 35 mmHg (4.7 kPa), HCO₃⁻ 10 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.
pH 7.08PaCO₂ 35 mmHg (4.7 kPa)HCO₃⁻ 10 mmol/L
1appropriate compensation
2added respiratory acidosis
3added respiratory alkalosis
5.Nursing fundamentalsMedium
A patient has just finished a glass of iced water. How should this affect taking an oral temperature?
AWait about 15–30 minutes, as the reading may be falsely low
BUse the reading but only if the patient says they feel warm
CAdd half a degree to the reading to correct for the drink
DTake it straight away, as cold drinks do not affect the mouth
6.Nursing fundamentalsHard
A pressure ulcer shows full-thickness skin loss with visible fat, but no bone, tendon or muscle is exposed. Which category is it?
ACategory 2
BCategory 3
CCategory 1
DCategory 4
7.Nursing math & unit conversionsMedium
Practice exercise (made-up values, not clinical guidance). A dose is charted at 1:35 AM. Which entry is the same time on the 24-hour clock? Click it.
1:35 AM
102:35
213:35
301:35
400:35
8.Nursing math & unit conversionsHard
Practice exercise (made-up values, not clinical guidance). A serum creatinine result is 4.1 mg/dL. Using 1 mg/dL = 88.4 µmol/L for creatinine, find c in µmol/L to the nearest whole number.
4.1 mg/dL1 mg/dL = 88.4 µmol/L
c = µmol/L
3Solutions
1.Clinical assessment scores
Answer: M = 3
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.
Motor score
M = 8 − 3 − 2 = 3
M3: abnormal flexion of the arms (decorticate posture)
Answer
M = 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 14/min → 0
SpO₂ 98% → 0
on air → 0
SBP 150 mmHg → 0
HR 58/min → 0
alert (A) → 0
T 35.5 °C → 1
Total and red scores
NEWS2 = 0 + 0 + 0 + 0 + 0 + 0 + 1 = 1
No parameter scores 3.
Risk group
low
Answer
low
3.Arterial blood gas interpretation
Answer: fully compensated
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 7.36: within 7.35–7.45
PaCO₂ 72 mmHg: high (35–45)
HCO₃⁻ 39 mmol/L: high (22–26)
Compensation
fully compensated
Answer
fully compensated
4.Arterial blood gas interpretation
Answer: added respiratory 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.
Expected PaCO₂
1.5·10 + 8 = 23 → 21–25 mmHg
Compare
measured: 35 mmHg → added respiratory acidosis
Answer
added respiratory acidosis
5.Nursing fundamentals
Answer: A · Wait about 15–30 minutes, as the reading may be falsely low
Why this is the answer
Hot or cold drinks, eating and smoking change the temperature in the mouth for a while. The nurse waits 15–30 minutes or uses another site.
Answer
A · Wait about 15–30 minutes, as the reading may be falsely low
6.Nursing fundamentals
Answer: B · Category 3
Why this is the answer
Category 3 involves full-thickness skin loss with subcutaneous fat visible. Category 2 is partial-thickness loss, and category 4 exposes bone, tendon or muscle.
Answer
B · Category 3
7.Nursing math & unit conversions
Answer: 01:35
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.
Convert the hour
1 AM → 01
Answer
01:35
Answer
01:35
8.Nursing math & unit conversions
Answer: c = 362 µmol/L
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.