July 31, 2014
Making Sense of Lab or Home Sleep Apnea Testing
Home sleep apnea tests don't always detect cases of sleep apnea and most don't detect other sleep disorders. Yet because they are inexpensive, many insurance carriers are not allowing the sleep study labs, except as a last resort. The Mayo Clinic does say the following: “Your doctor may make an evaluation based on your signs and symptoms or may refer you to a sleep disorder center. There, a sleep specialist can help you decide on your need for further evaluation. Such an evaluation often involves overnight monitoring of your breathing and other body functions during sleep.”
Tests to detect sleep apnea may include:
#1 - Nocturnal polysomnography. During this test, you're hooked up to equipment that monitors your heart, lung and brain activity, breathing patterns, arm and leg movements, and blood oxygen levels while you sleep.
#2 - Home sleep tests. In some cases, your doctor may provide you with simplified tests to be used at home to diagnose sleep apnea. These tests usually involve measuring your heart rate, blood oxygen level, airflow and breathing patterns. If you have sleep apnea, the test results will show drops in your oxygen level during apneas and subsequent rises with awakenings. If the results are abnormal, your doctor may be able to prescribe a therapy without further testing.
Portable monitoring devices don't detect all cases of sleep apnea, so your doctor may still recommend polysomnography even if your initial results are normal.
A USA Today story on the other hand promotes home sleep study tests. While they do present both sides, have no doubt that home testing is favored.
This is the attitude of many insurance carriers. "You get to sleep in your own bed with your own pillow," said Dr. Laddie Tackett, medical director for Anthem Blue Cross and Blue Shield in Kentucky. "It makes testing more accessible. It makes it more affordable. It makes it more convenient." But many doctors are skeptical. They say in-home tests -- which make up a small percentage of overall sleep tests -- aren't as thorough as lab testing.
The amount of data from a home study is significantly less than what is obtained from a lab sleep study. I can confirm that walking around with untreated sleep apnea is no fun and can be very wearing on your body. It took me about three weeks to feel fully rested and another month to feel like my body had healed from the wear sleep apnea had caused.
The home study equipment varies, but should include something that measures air flow, an instrument that measures the effort people make during respiration, and a finger device that measures blood oxygen saturation. The air flow sensor is placed under your nose, the respiration effort belt goes around your chest, and the oxygen saturation clip in put over your finger (generally next to the thumb).
Tackett says the home study equipment is relatively easy to use and most patients usually do well in the home setting. There is much discussion still taking place about where home testing fits into the overall sleep disorder setting.
The lab sleep study equipment is extensive. It includes about 25 sensors for the head, legs, and other body areas, two belts to monitor breathing and respiratory effort, and snoring microphones. The equipment measures breathing, air flow, respiratory effort, heart rate, oxygen levels, brain waves, snoring, and leg movements. It can detect about 80 types of sleep disorders.
Many doctors believe that it is a misconception that patients always sleep better at home and I would agree. Just knowing that your sleep study is being monitored with equipment that can determine if it is just sleep apnea or has other sleep disorders involved can make sleeping in a lab quite comforting.
Some patients will require lab tests before a CPAP machine is prescribed to determine is there are other sleep disorders present. Both the home and lab may have advantages and disadvantages and this is why a sleep specialist should do a proper assessment.