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 Morse fall scale: history of falling in the last 3 months: yes; secondary diagnosis: no; ambulatory aid: none, bed rest or nurse assists; IV therapy or saline lock: no; gait: normal, bed rest or wheelchair; mental status: knows own limits. Find the Morse total MFS.
0–125
MFS =
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 97% on room air, blood pressure 222/134 mmHg, pulse 38/min, alert, temperature 38.0 °C. Which clinical risk group does the patient fall into? Click it.
RR 14SpO₂ 97%airSBP 222HR 38AT 38.0 °C
1low
2low–medium
3medium
4high
3.Arterial blood gas interpretationMedium
Practice values: Na⁺ 143 mmol/L, glucose 25.9 mmol/L and urea 19.7 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.
Na⁺ 143 mmol/Lglucose 25.9 mmol/Lurea 19.7 mmol/L
Osm = mOsm/kg
4.Arterial blood gas interpretationHard
Practice values: Na⁺ 135, Cl⁻ 112, HCO₃⁻ 15 mmol/L and albumin 31 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).
AThe first urine of the morning is kept and the rest of the day's urine is discarded
BThe first urine of the morning is discarded and the time noted, then all urine is kept
COnly urine passed at night is collected
DA sample is taken every four hours and the rest discarded
6.Nursing fundamentalsHard
Which statement by a visitor shows a need for further teaching about contact precautions?
A"I'll take off the gown and gloves before I leave the room."
B"I'll clean my hands as I leave the room."
C"I'll put on the gown and gloves before I go in."
D"I'll take the gown off at home after I leave the hospital."
7.Nursing math & unit conversionsMedium
Practice exercise (made-up values, not clinical guidance). A dose is charted at 5:00 AM. Which entry is the same time on the 24-hour clock? Click it.
5:00 AM
105:00
204:00
306:00
417:00
8.Nursing math & unit conversionsHard
Practice exercise (made-up values, not clinical guidance). An infusion starts at 23:00 and finishes at 05:15 the next morning (24-hour clock). How many minutes t did it run?
23:0005:15
t = min
3Solutions
1.Clinical assessment scores
Answer: MFS = 25
Morse fall scale: six items. History of falling: no 0, yes 25. Secondary diagnosis: no 0, yes 15. Ambulatory aid: none, bed rest or nurse assistance 0; crutches, cane or walker 15; holding on to furniture 30. IV therapy or saline lock: no 0, yes 20. Gait: normal, bed rest or wheelchair 0; weak 10; impaired 20. Mental status: knows own limits 0; overestimates or forgets limits 15. The total runs from 0 to 125. Risk cut-offs differ between hospitals; a common set is 0–24 low, 25–44 moderate and 45 or more high.
Score each item
history of falling in the last 3 months: yes → 25
secondary diagnosis: no → 0
ambulatory aid: none, bed rest or nurse assists → 0
IV therapy or saline lock: no → 0
gait: normal, bed rest or wheelchair → 0
mental status: knows own limits → 0
Add
Morse total = 25 + 0 + 0 + 0 + 0 + 0 = 25
Answer
MFS = 25
2.Clinical assessment scores
Answer: 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 14/min → 0
SpO₂ 97% → 0
on air → 0
SBP 222 mmHg → 3
HR 38/min → 3
alert (A) → 0
T 38.0 °C → 0
Total and red scores
NEWS2 = 0 + 0 + 0 + 3 + 3 + 0 + 0 = 6
At least one parameter scores 3.
Risk group
medium
Answer
medium
A total of 5 or more calls for an urgent clinical response.
3.Arterial blood gas interpretation
Answer: Osm = 332 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 + 25.9 + 19.7 = 331.6 ≈ 332 mOsm/kg
Answer
Osm = 332 mOsm/kg
4.Arterial blood gas interpretation
Answer: AGc = 10.25 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 = 135 − (112 + 15) = 8
Correction for albumin
8 + 0.25·(40 − 31) = 10.25 mmol/L
Answer
AGc = 10.25 mmol/L
Still within about 8–12 after correction.
5.Nursing fundamentals
Answer: B · The first urine of the morning is discarded and the time noted, then all urine is kept
Why this is the answer
The patient empties the bladder at the start and that urine is discarded. All urine for the next 24 hours is kept, including a final void at the end time.
Answer
B · The first urine of the morning is discarded and the time noted, then all urine is kept
6.Nursing fundamentals
Answer: D · "I'll take the gown off at home after I leave the hospital."
Why this is the answer
PPE is removed in or at the door of the patient's room and disposed of there, followed by hand hygiene. Wearing it out of the room spreads the organism.
Answer
D · "I'll take the gown off at home after I leave the hospital."
7.Nursing math & unit conversions
Answer: 05:00
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
5 AM → 05
Answer
05:00
Answer
05:00
8.Nursing math & unit conversions
Answer: t = 375 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.