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Positive airway pressure
PAP ventilation is also commonly used for critically ill patients in hospital with respiratory failure, and in newborn infants (neonates). In these patients, PAP ventilation can prevent the need for endotracheal intubation, or allow earlier extubation. Additional recommended knowledge
MachineA continuous positive airway pressure (CPAP) machine is used mainly by patients for the treatment of sleep apnea at home. Obstructive sleep apnea occurs when the upper airway becomes narrow as the muscles relax naturally during sleep. This reduces oxygen in the blood and causes arousal from sleep. The CPAP machine stops this phenomenon by delivering a stream of compressed air via a hose to a nasal pillow, nose mask or full-face mask, splinting the airway (keeping it open under air pressure) so that unobstructed breathing becomes possible, reducing and/or preventing apneas and hypopneas. This has the additional benefit of reducing or eliminating snoring. The CPAP machine blows air at a prescribed pressure (also called the titrated pressure). The necessary pressure is usually determined by a sleep physician after review of a study supervised by a sleep technician during an overnight study (polysomnography) in a sleep laboratory. The titrated pressure is the pressure of air at which most (if not all) apneas and hypopneas have been prevented, and it is usually measured in centimetres of water (cm H2O). The pressure required by most patients with sleep apnea ranges between 6 and 14 cm H2O. A typical CPAP machine can deliver pressures between 4 and 20 cm H2O. More specialized units can deliver pressures up to 25 or 30 cm H2O. CPAP treatment can be highly effective in treatment of obstructive sleep apnea. [1] For some patients, the improvement in the quality of sleep and quality of life due to CPAP treatment will be noticed after a single night's use. Prospective CPAP candidates are often reluctant to use this therapy, since the nose mask and hose to the machine look uncomfortable and clumsy, and the airflow required for some patients can be vigorous. Some patients adjust to the treatment within a few weeks, others struggle for longer periods, and some discontinue treatment entirely. However, studies show that cognitive behavioral therapy at the beginning of therapy dramatically increases compliance - up to 148%. [2] Therapy compliance on the part of the patient can be improved with support from a durable medical equipment (DME) provider,[citation needed] including allowing the patient his or her choice of PAP devices. PAP manufacturers frequently offer different models at different price ranges, and PAP masks have many different sizes and shapes, so that some users need to try several masks before finding a good fit. Given that sleep apnea is a chronic health issue and doesn't go away, ongoing care is needed to maintain CPAP therapy. Based on the study of cognitive behavioral therapy (referenced above), ongoing [chronic care management] is the best way to help patients continue therapy by educating them on the [health risks of sleep apnea] and providing motivation and support. HistoryProfessor Colin Sullivan first developed the Continuous Positive Airway Pressure (CPAP) system at Royal Prince Alfred Hospital in 1981. Types
Components
Optional features
Such features generally increase the likelihood of PAP tolerance and compliance. [3] Care and maintenanceAs with all durable medical equipment, proper maintenance is essential for proper functioning, long unit life and patient comfort. The care and maintenance required for PAP machines varies with the type and conditions of use, and are typically spelled out in a detailed instruction manual specific to the make and model. Most manufacturers recommend that the end user perform weekly maintenance. Units must be checked regularly for wear and tear and kept clean. Worn or frayed electrical connections may present a shock or fire hazard; worn hoses and masks may reduce the effectiveness of the unit. Most units employ some type of filtration, and the filters must be cleaned or replaced on a regular schedule. Hoses and masks accumulate exfoliated skin, particulate matter, and can even develop mold. Humidification units must be kept free of mold and algae. Because units use substantial electrical power, housings must be cleaned without immersion. PortabilitySince continuous compliance is an important factor in the success of treatment, it is of importance that patients who travel have access to portable equipment. Progressively, nPAP units are becoming lighter and more compact, and often come with carrying cases. Dual-voltage power supplies permit many units to be used internationally. Air travel presents special considerations. Most airport security inspectors have seen the portable machines, so screening rarely presents a special problem. Increasingly, machines are capable of being powered by the 400 Hz power supply used on most commercial aircraft and include manual or automatic altitude adjustment. Some patients on PAP therapy also use supplementary oxygen. When provided in the form of bottled gas, this can present an increased risk of fire and is subject to restrictions. (Commercial airlines generally forbid passengers to bring their own oxygen.) As of November, 2006, most airlines permit the use of oxygen concentrators. Availability
In a hospital settingPAP ventilation is often used for patients who have acute type 1 or 2 respiratory failure. Usually PAP ventilation will be reserved for the subset of patients for whom oxygen delivered via a face mask is deemed to be insufficient or deleterious to health (see CO₂ retention). Usually, patients on PAP ventilation will be closely monitored in an intensive care, high dependency, coronary care unit or specialist respiratory unit. The most common conditions for which PAP ventilation is used in hospital are congestive cardiac failure and acute exacerbation of obstructive airways disease, most notably exacerbations of COPD and asthma. It is not used in cases where the airway may be compromised, or consciousness is impaired. The mask required to deliver CPAP must have a tight seal, and be held on very firmly. Most people find wearing the mask uncomfortable. Breathing out against the positive pressure resistance (the expiratory positive airway pressure component, or EPAP) is also unpleasant. These factors lead to inability to continue treatment due to patient intolerance in about 20% of cases where it is initiated. Obviously those who suffer an anxiety disorder or claustrophobia are more likely to be unable to tolerate PAP treatment. Sometimes medication will be given to assist with the anxiety caused by PAP ventilation. Unlike PAP used at home to splint the tongue and pharynx, PAP is used in hospital to improve the ability of the lung to exchange oxygen and carbon dioxide, and to decrease the work of breathing (the energy expended moving air into and out of the alveoli). This is because:
References
Categories: Intensive care medicine | Medical equipment | Medical treatments | Pulmonology | Sleep |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Positive_airway_pressure". A list of authors is available in Wikipedia. |