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10. Evidence for recommendations on the oxygen use and delivery
10.1 Pulse oximetry for detection of hypoxaemia
1. Pulse oximetry is recommended to determine the presence of hypoxaemia and to guide administration of oxygen therapy in all infants and children with
hypoxaemia.
Strong recommendation, low quality evidence
he panel noted that although there are no studies comparing arterial blood gases versus pulse oximetry in children, the meta-analysis in adults shows a very high
correlation. Pulse oximetry is non-invasive, feasible to implement, and does not require any special skills. It is, therefore, more suitable for use more widely.
10.1.1 Evidence and summary of findings
A systematic review of the accuracy of pulse oximetry in children was not found. A meta-analysis of 74 studies of adult subjects, published between 1976-1994, reported
the correlation between pulse oximetry measurements and arterial blood gas ABG analysis, and investigated how a number of factors afected this relationship [Jensen,
1998]
see GRADE table A7.28 . he available low quality evidence shows that pulse
oximetry is the best non-invasive method of detecting hypoxaemia, and should be made globally available.
Subjects included in the studies were healthy adult volunteers 25.7, respiratory patients 20.3, cardiac and thoracic surgical patients 18.9, critically ill patients
16.2, and athletes 5.4. Of 39 studies that reported suicient data on the number of subjects and data points to calculate the correlation coeicient r between pulse
oximetry and ABG, the weighted mean r was 0.895 +- 0.014. his estimate did not signiicantly change when only higher quality studies were considered r = 0.883. he
highest correlation was in healthy volunteers r = 0.957, and the lowest in critically ill patients r = 0.760.
he accuracy of oximeters difered depending on the oximeter make, particularly at saturations below 70. Finger probes were found to have a signiicantly higher
correlation with SaO
2
than ear probes p 0.0001. he correlation coeicient in ive studies of hypoxic subjects SaO
2
67.6 -87.8 was high r = 0.938. Factors that reduced accuracy included dyshemoglobinemia, hypothermia, and skin pigmentation.
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10.1.2 Benefits and risks
Benefits As compared to clinical signs, pulse oximetry is:
n
much more accurate at detecting hypoxaemia
n
requires less training than detection of clinical signs As compared to blood gas analysis, pulse oximetry is:
n
non-invasive
n
faster
n
less expensive
n
requires minimal infrastructure and no laboratory facilities
n
less prone to erroneous measurements
n
allows continuous monitoring Risks
Unlike blood gas analysis, pulse oximetry does not give an indication of ventilation pCO
2
or pH.
10.1.3 Acceptability and feasibility
Given the large global burden of hypoxaemia, the mortality beneit in detecting and treating with oxygen, and the inaccuracy and unreliability of the detection
and interpretation of clinical signs, the cost of pulse oximetry is justiied. Blood gas analysis is expensive for most low-resource settings, given the high level of laboratory
infrastructure required, as well as the cost and diiculty in obtaining and analysing an arterial sample in a timely manner.
Oximeters are becoming more afordable. Depending on the type and make, prices can range from US 35–400 digit oximeters, US 60–1200 hand-held oximeters
to US 800–4500 oximeters with monitor displays, which can also be used in ICU and theatre.
Several studies have shown the feasibility of implementing and sustaining oxygen systems, including pulse oximetry, in low-resource district and provincial hospitals
in developing countries, including Malawi and Papua New Guinea [Duke, 2008; Enarson, 2009].
10.2 Clinical signs in detection of hypoxaemia in children
a Use pulse oximetry wherever possible is recommended for the detection of hypoxaemia in children with severe lower respiratory infections. If oximetry is
not available then the following clinical signs could be used to guide the need for oxygen therapy:
— central cyanosis — nasal laring
— inability to drink or feed where this is due to respiratory distress — grunting with every breath
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