What is Sleep Apnea?Apnea is a Greek word meaning “without breath.”
There are three types of apnea during sleep: central, obstructive and mixed. Mixed apnea is a combination of central and obstructive sleep apnea. It can be argued with some conviction that chronic hyperventilation offers an explanation for both types of sleep apnea.
Central Sleep Apnea
Central sleep apnea affects approximately 5% of sufferers and results from the brain not sending the right signals to breathe. Excessive breathing volume during sleep causes a reduction in the partial pressure of carbon dioxide. This shifts the pH of the blood in an alkaline direction. To maintain the pH within normal levels, a natural bodily response is to hold the breath, allowing the pH to revert to normal. In other words, central apnea occurs from breathing in excess of metabolic requirements.
Obstructive Sleep Apnea
During your school days, you may remember reading about Joe the “fat boy” from the Pickwick papers written by Charles Dickens in 1837.
Joe ate in great quantities and was liable to fall asleep during any situation. His breathing was heavy, he snored and he was continuously sleepy. Originally described as the Pickwickian syndrome, his breathing was later labeled as obstructive sleep apnea syndrome.
While obstructive sleep apnea more often affects men with a neck size of 17 inches or larger, it can also affect children and adults who are not overweight. Children who breathe through their mouth are at risk of developing cranio-facial changes, such as undeveloped jaws, smaller airways, and narrow faces. It also increases the likelihood of the child developing lifelong sleep apnea.
Obstructive sleep apnea is the most common type of apnea and is characterized by holding the breath from collapse of the upper airways during sleep. This holding of the breath, which prevents airflow to the lungs, may occur between five and fifty times per hour. Each breath hold can range from a few seconds to over one minute, causing one’s blood oxygen saturation to decline to as low as 50%.
After a period of holding the breath during sleep, the centre within the brain that controls breathing alerts the rest of the brain that the breath is being held and the individual partially wakes up. This is followed by gasping, a sharp intake of breath, and spluttering, which is often of great concern to sleep partners who in turn suffer from sleep deprivation. The sufferer is unaware that he or she is holding his or her breath, often feels that he or she slept well but wonders why he or she is so tired during the day.
All patients with sleep apnea breathe extremely heavily while sleeping. A normal routine is thunderous snoring followed by complete cessation of the breath.
Imagine sucking air through a collapsible rubber tube. As one sucks air through the tube, the walls of the tube tend to collapse inwards from the pressure created by drawing air. During a gentle draw of air, pressure is minimal and the inner walls of the tube do not collapse. However, during a strong draw of air, the walls can collapse and the more effort one makes to suck air through the tube, the more the walls collapse.
An engineer looking at this problem might offer two solutions. The first is to widen the tube. The second is to reduce the airflow.
Widening a human airway through surgery is a last resort. While losing weight from around the neck region is helpful, a more plausible option is to reduce breathing volume.
Large breathing volume causes the airway walls to collapse, resulting in holding of the breath. During the cessation of the breath, the chest and diaphragm continue to try to draw air into the lungs. This results in jerking and heaving as the diaphragm presses downward. The greater the heaving of the chest and diaphragm, the more the airway walls are drawn inward. Eventually, the patient begins to breathe again.
Symptoms resulting from sleep apnea include excessive daytime sleepiness, waking up tired, loud snoring, holding the breath during the night, loud snorts, gasps upon resumption of breathing, dry throat, dry mouth, and headaches in morning, problems with memory and concentration, heartburn or reflux, swelling of the legs, needing to urinate during the night, sweating during sleep, chest pain, and elevations in blood pressure. Of course, this loud snoring accompanied by loud snorts and gasps can also lead to marital problems.
Side effects of CPAP
The normal treatment for obstructive sleep apnea is a CPAP (continuous positive airway pressure) machine. The patient wears a mask over the face and air is applied at a pressure that exceeds the airway opening pressure, thereby enabling the patient to breathe without cessation. In simple terms, it may be best understood as a small vacuum cleaner working in reverse, applying sufficient air pressure to force the airways open.
The CPAP can resolve apneas in many patients, leading to improved sleep quality, decreased sleepiness, and lower blood pressure.1,2,3,4
The machine helps the patient as long as he or she continues to use it. On the downside, it does nothing to address the major contributory factor of sleep apnea, namely chronic overbreathing. Wearing a mask during sleep can be claustrophobic, uncomfortable, cumbersome, and inconvenient, and getting tangled in the tube can be annoying. The air is very dry, which may cause rhinitis, a dripping nose, a blocked nose, and nasal irritation. Even when the mask is worn correctly, the feeling of the airflow is often described as putting ones head out of a car window while the car is moving at 30 miles per hour. Partners and patients often find the humming of the machine very distracting. The machine has to be cleaned on a regular basis, but few do this. Overall, while it is accepted as the gold standard of treatment, the CPAP machine has major short comings.
During one study of 300 patients referred to the London Chest Ventilatory support unit, it was found that 96% of patients complained of at least one side effect resulting from the therapy, while 45% complained of a side effect from the nasal mask.5
In a study of 80 patients, Verse et al. found that the most prevalent side effects were disturbance of the mask during the night (71.3%), dry mouth (47.5%), dry nose (46.3%), pressure marks from the mask (41.3%), crusts within the nasal cavity (38.8%), and hearing loss (26.3%). Mouth and nose dryness were considered the most irritating side effects.6
In another study of 41 patients with OSAS, the paper noted that “the most frequently reported problems were a tender region on the bridge of the nose and discomfort associated with a dry nasal mucosa. Although CPAP treatment was initially accepted by most patients, adverse effects and other difficulties decreased patient compliance, with time, in many cases.”7
A paper published in The Canadian Respiratory Journal observed that “compliance is a significant problem and has been incompletely assessed in long-term studies.” After evaluating 80 patients to determine long-term compliance with CPAPA, the authors concluded that “although many patients with OSA derive subjective benefit from, and adhere to treatment with CPAP, a significant proportion of those so diagnosed either do not initiate or eventually abandon therapy.”8
The journal Sleep found that only 40% of the 162 newly diagnosed patients who required CPAPA therapy accepted the treatment. The paper noted that compliance was higher in higher socioeconomic groups than the lower.9 Other researchers found that “failure to comply with treatment has been reported to be as high as 25 to 50%, with patients typically abandoning therapy during the first 2 to 4 weeks of treatment.”10
According to Broström A et al., “Adherence to CPAP treatment is a multifaceted problem including patient, treatment, condition, social, and healthcare related factors. Knowledge about facilitators and barriers for adherence to CPAP treatment can be used in interventional strategies.”11
References
1. Pepperell JC, Ramdassingh-Dow S, Crosthwaite N, et al. Ambulatory blood pressure after therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnea: a randomised parallel trial. Lancet. 2002;359:204-10.
2. Hack M, Davies RJ, Mullins R, et al. Randomised prospective parallel trial of therapeutic versus subtherapeutic nasal continuous positive airway pressure on simulated steering performance in patients with obstructive sleep apnea. Thorax. 2000;55:224-31.
3. Norman D, Loredo JS, Nelesen RA, et al. Effects of continuous positive airway pressure versus supplemental oxygen on 24-hour ambulatory blood pressure. Hypertension. 2006;47:840-5.
4. Shivalkar B, Van de Heyning C, Kerremans M, et al. Obstructive sleep apnea syndrome: more insights on structural and functional cardiac alterations, and the effects of treatment with continuous positive airway pressure. J Am Coll Cardiol. 2006;47:1433-9.
5. Kalan A, Kenyon GS, Seemungal TA, Wedzicha JA. Adverse effects of nasal continuous positive airway pressure therapy in sleep apnea syndrome. J Laryngol Otol. 1999 Oct;113(10):888-92.
6. Verse T, Lehnhardt E, Pirsig W, Junge-Hülsing B, Kroker B. [What are the side-effects of nocturnal continuous positive pressure ventilation (nCPAP) in patients with sleep apnea for the head-neck region?].[Article in German] Laryngorhinootologie. 1999 Sep;78(9):491-6.
7. Kuhl S, Hollandt JH, Siegert R. [Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). II: Side-effects of nCPAP therapy. Effect on long-term acceptance] Laryngorhinootologie 1997 Oct;76(10):608-13.
8. Wolkove N, Baltzan M, Kamel H, Dabrusin R, Palayew M. Long-term compliance with continuous positive airway pressure in patients with obstructive sleep apnea Can Respir J. 2008 Oct;15(7):365-9.
9. Simon-Tuval T, Reuveni H, Greenberg-Dotan S, Oksenberg A, Tal A, Tarasiuk A. Low socioeconomic status is a risk factor for CPAP acceptance among adult OSAS patients requiring treatment. Sleep. 2009 Apr 1;32(4):545-52.
10. Zozula R, Rosen R Compliance with continuous positive airway pressure therapy: assessing and improving treatment outcomes. Curr Opin Pulm Med. 2001 Nov;7(6):391-8.
11. Broström A, Nilsen P, Johansson P, Ulander M, Strömberg A, Svanborg E, Fridlund B Putative facilitators and barriers for adherence to CPAP treatment in patients with obstructive sleep apnea syndrome: a qualitative content analysis. Sleep Med. 2010 Feb;11(2):126-30. Epub 2009 Dec 9. |
