Sleep apnea is a disorder in which pauses in breathing occur for about 10 to 30 seconds during one’s sleep (American Academy of Family Physicians 2005). An “apnea” is an episode without breath in which one’s body simply skips breathing momentarily. Of the 18 millions Americans that have sleep apnea, 90% don’t even know they have it because they don’t recall waking up hundreds of times during the night due to a break in REM sleep. They feel tired and moody during the day, craving the occasional morning, afternoon, and evening nap; but they often don’t realize that they’re suffering from a disorder. The best means for diagnosis of sleep apnea is an overnight polysomnography that tracks blood pressure (BP), respiration (resp), sympathetic nerve activation (SNA), and body movements (Benedictis 2006).

There are two types of sleep apnea: obstructive and central. Obstructive sleep apnea (OSA) occurs in one out of every five people and is caused by an obstruction in the throat. The obstruction is any physical hindrance in the airway, this can be caused by anything from obesity to enlarged tonsils. People who are more vulnerable to OSA are men, overweight individuals, and individuals over the age of 40. Central sleep apnea (CSA), the main focus of this paper, is caused by an error in the thalamus, the part of the brain that controls involuntary breathing. During CSA, there is no effort by the person’s body to breath; no struggle by respiratory muscles, just stiffness of the body without breathing. Mixed apnea, which is a combination of OSA and CSA, also exists (UMMC 2004, ASAA 2007).

Circadian rhythm sleep, or “normal sleep”, consists of a period of time in which the body is at rest to avoid exhaustion (UMMC 2004). During circadian rhythm sleep, one exhibits tidal breathing in which about 700 mL of air is inhaled and filtered through the lungs for oxygen extraction before exhalation. During circadian rhythm sleep, one’s body should comply with average standards such as an average pulse rate between 60 and 80 beats per minute and average resting blood pressure around 120/80 mmHg. The average respiratory rate for a resting adult is between 12 to 18 breaths per minute; however children take about 20 to 30 breaths per minute (UI Health Care 2005). There are two major respiratory gases: oxygen (O₂) and carbon dioxide (CO₂). The average amount of oxygen in expired breath during tidal breathing is 250 mL of oxygen per breath and for carbon dioxide it is 220 mL of carbon dioxide per breath (George 2007). The average blood pH for a resting adult is 7.35 to 7.45 and red blood cells should be about 33% concentrated with hemoglobin (Hb) (Encyclopedia of Surgery Information 2005).

Proposed Solution

Apneas disturb circadian rhythm sleep and cause the individual to wake up in the night gasping for air. During an apnea, the individual’s pulse, blood pressure, and respiratory rate decrease and they submit to hypoxia (lower than threshold oxygen levels) and hypercapnia (high carbon dioxide levels) (ASAA 2007). There are several risks to people with sleep apnea, among these are higher risks of car accidents due to drowsiness, stroke due to increased blood viscosity, depression due to lack of sleep and low sexual arousal, heart disease, heart attack, heart failure, kidney failure, seizures, headaches, eye disorders, and memory loss. According to doctors at the University of Maryland Medical Center, people with sleep apnea must be diagnosed and treated to help reduce their chances of these terrible risks (Rice et al. 2006).

After diagnosing a patient with OSA, doctors will recommend a series ideas that will help reduce the amount of apneas a person has. There is positional therapy, dieting, exercising, and surgery. The 20% of the American population with OSA has great chances to permanently correct their disorder by simply losing weight, surgically widening their airway, or surgically moving their jaw forward (Rice et al. 2006, ASAA 2007).

The first thing a doctor will say to their newly diagnosed CSA patient is to avoid alcohol and central nervous system depressants because they worsen CSA by relaxing the muscles and impairing the brain. When looking at CSA, there are many solutions available to relieve it, however none of the devices on the market are a permanent cure for this disorder. In order for a device to help the individual, it must first detect an apnea and then trigger a mechanism to induce breathing without waking them (ASAA 2007, Encyclopedia of Surgery Information 2005).

Some currently patented detection devices are adaptive servo-ventilation devices, snorkels, and sleep apnea detection apparatuses. Our company’s proposed detection device for CSA will be a pulse oximeter, which utilizes infrared light shining through one’s finger to measure the Hb concentration on red blood cells.

A pulse oximeter clips onto the patient’s finger and can be kept on for the whole night. It will sense Hb concentration below 33%, which correlates with hypoxia below 75% O₂ saturation on red blood cells. When O₂ saturation drops below 75%, the photodetector senses an increased amount of infrared light, so the pulse oximeter can trigger the device to induce breathing.

Pulse oximeters are the best detection device because they are comfortable, don’t dry skin out/chaff, are used widely in hospitals, and don’t cause claustrophobia since they are not on the person’s face. For people who move around in their sleep, our company can provide an add-on option to the pulse oximeter that utilizes Bluetooth technology to communicate with the breath induction device rather than a wire. Pulse oximeters are accurate in detecting hypoxia about 80% of the time (AARC 1991, UMMC 2004).

Examples of breath induction devices for CSA patients are continuous positive airway pressure (CPAP), electrical stimulators, and drugs. The most common breath induction device is the CPAP, which delivers a constant flow of air pressure using a nasal mask while the patient is sleeping. Since it is unnecessary to continuously apply pressure to the airway even when the patient is not having an apnea, the R&D department of our company should conduct research to create a positive airway pressure device that administers pressure only when activated by the pulse oximeter (if our company chooses to invest in sleep apnea). CPAP is the most widely used and accepted method for CSA patients because it effectively prevents the patient from having an apnea due to its continuous pressure, thereby providing the patient with smooth respiration throughout the night (Matthews 2003).

On the negative side, the CPAP can cause claustrophobia, dry skin, and discomfort. It is also very large, must be cleaned/maintained meticulously, and cannot be kept in direct sunlight or exposed to excessive amounts of heat. There are several different types of CPAPs like the Auto-CPAP, Smart CPAP, and Goodnight 420E. Our company will use the Auto-CPAP because it is more compact and lightweight than the others, automatically adjusts to altitude changes, and has a display screen that is very user friendly (REMstar 2006).

Our company’s proposed solution consists of a pulse oximeter that detects low Hb/oxygen levels and a CPAP that induces breathing through constant pressure on the airway. This solution works via the feedback loop in figure 5. Although the detection method is wonderful, the breath induction method is already widely in use with many established competitors. Our company should not invest in a sleep apnea device patent because, although the pulse oximeter can cost as low as $80, the CPAP alone is around $800 each at leading companies. A good investment for our company could be not to create a patent, but to have the R&D department create a better CPAP device than leading companies. In conclusion, a patent for a sleep apnea device is not currently a good investment for our company (AARC 1991, Rice 2006, REMstar 2006).

-Amy Shah