Definition for hypoxemia: arterial oxygen saturation < 90% using a pulse oximeter (corresponds to an arterial oxygen tension of 60-70 mm Hg, depending on age, altitude, blood pH, temperature and other factors).
Endpoints: To identify those infants to receive oxygen therapy and referral to the local hospital.
Patient population in study of Usen et al: based on enrollment in a Hemophilus influenzae vaccination study:
(1) Exclusions: age < 2 months (not candidates for vaccine), Down's syndrome, structural heart disease
(2) 1,072 children, with 5.9% having hypoxemia
(3) mean age: 8 months (non-hypoxemic) and 9 months (hypoxemic)
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Hypoxemia if 1 or more of the following is present
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Finding
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Dyke
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Onyan-go
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Usen (1)
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Usen (2)
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Weber
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WHO
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inability to feed or drink
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x
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cyanosis
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x
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x
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x
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x
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respiratory rate in breaths/minute
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>= 90
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>= 70
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>= 90
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>= 70
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severe chest indrawing
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inter-costal
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x
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grunting respirations
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x
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x
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abnormally sleepy
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x
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head nodding
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x
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x
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inability to cry
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x
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x
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from Table 2, Usen page 89
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Criteria
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Sensitivity
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Specificity
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Positive Predictive Value
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Negative Predictive Value
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Dyke
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73%
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72%
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13.9%
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97.7%
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Onyango
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84.2%
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63.3%
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11.3%
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98.6%
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Usen (1)
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69.3%
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80.4%
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17.8%
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97.6%
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Usen (2)
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69.8%
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78.6%
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16.9%
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97.7%
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Weber
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71.4%
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77.1%
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16.3%
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97.7%
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WHO
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80.9%
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62.5%
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11.9%
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98.1%
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from Table 2, Usen page 89
The criteria appear fairly good for excluding hypoxemia (high negative predictive value).
Independent predictors for hypoxemia using logistic regression model (Usen et al):
(1) cyanosis
(2) rapid respiratory rate
(3) grunting respirations
(4) head nodding
(5) absence of a history of fever
(6) no spontaneous movements during the examination
