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Two standard tables (average and normal limits) are shown for comparison.

Table 17.1Vital signs (average)
Table 17.2Paediatric vital signs: American College of Surgeons


The pulse oximeter measures oxygen saturation of arterial blood (SpO2).

Facts and figures

In a healthy young person the O2 saturation should be 95–99%. It varies with age, the degree of fitness, current altitude and oxygen therapy. Studies show that Caucasian race, obesity and male sex but not smoking are associated with lower SpO2 readings.1

The ideal value is 97–100%.

The median value in neonates is 97%, in young children 98% and adults 98%.

Target oxygen saturation

  • Asthma—the aim is to maintain SpO2 > 94%

  • Acute coronary syndromes ≥ 94%

  • Opioid effect ≥ 94%

  • Type 1 (hypoxemic) respiratory failure (e.g. interstitial lung disease, pneumonia, pulmonary oedema) ≥ 94%

  • Severe COPD with hypercapnoeic respiratory failure 88–92%

  • Critical illness (e.g. major trauma, shock) 94–98%

  • Children > 94% (< 94% is a concern)

Indications for oxygen therapy to be beneficial

  • Australian guideline to improve quality of life > 88%

  • UK: adults < 50 years 90%, asthma 92.3%

Availability and cost

Pulse oximeters are readily available from medical and surgical suppliers with a range in cost from about $30 to $2000. A good-quality unit is available for about $200 to $400.


In the author’s rural practice, over a period of 10 years, the most common cause of sudden death was myocardial infarction, which was responsible for 67% of deaths in the emergency situation. The importance of confirming early diagnosis with the use of the electrocardiogram (ECG) and serum markers, especially troponin, is obvious. A summary of acute coronary syndromes is presented in Table 17.3.

Table 17.3Types of acute coronary syndromes

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