Oxygen saturation is a clinical measurement that determines what percentage of a patient’s red blood cells are saturated with oxygen after passing through the lungs. It is a result that reflects not only how well a patient’s lungs are working but also how effectively oxygen is being delivered to all parts of the body. In a healthy child breathing room air, the oxygen saturation levels will be between 96 and 98 percent. Falling levels of oxygen saturation are concerning to physicians and may require intervention.
SIGNIFICANCE
Oxygen saturation is an accurate measurement that reflects multiple aspects of a child’s cardiovascular health. Monitoring the percent of red blood cells saturated with oxygen tells a physician how well a child is breathing, how efficiently the oxygen is being distributed to the body and how well oxygen is unloaded from red blood cells at its destination. A disruption in any of these processes will decrease the child’s oxygen saturation and can necessitate therapeutic intervention.
FUNCTION
Oxygen saturation sensing in a healthy child breathing room air will reveal a saturation rate between 96 and 98 percent. This is the normal range for a healthy adult as well. A disruption in oxygen metabolism can cause saturation levels to drop below 95 percent, at which point a physician might order intervention. Saturation levels that fall below 90 percent often require oxygen therapy, in which higher than normal amounts of oxygen are fed directly into the child’s nose.
TYPES
Typically, oxygen saturation is measured with a pulse oximeter. This is a painless clip that can be attached to the child on either a finger, toe or even ear lobe and detects the extent of oxygen saturation in the blood in that region, however in more sensitive cases physicians may draw arterial blood from the child to directly measure oxygen levels.
BENEFITS
Since measurement is simple, painless and cost-effective, it is a very efficient method for catching a change in oxygen delivery before severe consequences occur. Home-use pulse oximeters are widely available for home monitoring of oxygen saturation levels both at rest and during exercise.
WARNING
In a hospital, falling oxygen levels are detected immediately and corrected in extreme situations with oxygen therapy. If you are monitoring your at-risk child at home, however, and you detect a drop in oxygen levels, consult your physician immediately. Efficient correction of low oxygen levels can help prevent long-term consequences and allow your child to lead a healthier life.
RESPIRATORY PROBLEMS
Most children with low oxygen saturation have a respiratory disorder. Any disease that interfere with oxygen flow through the lungs can cause a low oxygen saturation, including conditions such as pneumonia, croup or chronic diseases such as cystic fibrosis or bronchopulmonary disease, which makes the lungs stiff.
Newborns who breathe irregularly or who have apneic periods where they stop breathing may also have low oxygen saturation.
Children with asthma may have normal oxygen saturation, except when they have an asthma attack. Giving supplemental oxygen normally raises the oxygen saturation in children with respiratory disease, although severe asthma or lung damage, which narrows and constricts the tubes in the lungs, can make it difficult for oxygen to reach the lungs.
POOR TISSUE PERFUSION
If your child has poor tissue perfusion, the pulse oximeter will have difficulty reading the oxygen saturation accurately. Poor tissue perfusion means that not enough blood is flowing to an area. Extreme cold, decreased blood volume due to blood loss or dehydration, very low blood pressure, heart failure or diseases that disrupt blood flow to the arms and legs can all cause low oxygenation saturation due to poor perfusion.
An irregular heartbeat can make it difficult for the pulse oximeter to record an accurate reading. If the child has a blood pressure cuff on the same arm as a pulse oximeter, the cuff interferes with blood flow when it pumps up, causing low readings.
MOVEMENT
If you’re child is moving around or crying, SpO2 may be artificially low because the machine can’t lock onto the signal long enough to read it. During a seizure, SpO2 will also fall, both because of decreased oxygenation and because of the child’s movement. Vibrations in a moving vehicle, plane or helicopter, during a medical transport, for instance, will also interfere with readings.
OTHER PROBLEMS
If your child has sickle cell anaemia, the irregular and abnormal shapes of the red blood cells can cause SpO2 to be either too high or too low. A number of mechanical problems can also interfere with the pulse oximeter, causing low readings. Very bright light shining on the pulse oximeter can skew the readings, as can very dark nail polish on a fingernail. Dark skin colour does not cause low readings, however. Pulse oximeters do not measure carbon dioxide and can’t diagnose respiratory failure due to carbon dioxide retention, states S.J. Fearnley of the Department of Anaesthetics at Torbay Hospital in the United Kingdom.
