Oxygen Concentrators Oxygen concentrators (sometimes referred to as oxygen generators) can be used as an alternative to compressed gas cylinders. They produce 90–95% oxygen from room air, by absorbing nitrogen. Portable units generally produce 4–10 l/min ( Fig. 1.4), and larger devices, producing up to 25 l/min and capable of supplying several anaesthetic machines can also be obtained. All of these devices are electrically operated, so a power failure will result in a failure of oxygen supply unless a standby generator, or a battery backup and power inverter are available. Alternatively, a cylinder of oxygen can be retained for emergency use. Since the flow of gas from a portable machine is relatively low, the emergency oxygen button on an anaesthetic machine will not function correctly, but turning up the flow meter can rapidly flush anaesthetic vapour from a breathing system.

The low flow and lower pressure of gas supplied from these units limits their use with some ventilators, and with larger animals. However the small, relatively portable units are well-suited for use in small procedure rooms, where transport and storage of oxygen cylinders can be a problem. Newer devices are noticeably quieter than older models, and noise is not an issue if a larger unit is sited away from the immediate theatre area.

The purchase cost of this equipment has fallen dramatically in recent years, and they can now be considered an economical and convenient alternative to compressed gas cylinders. Oxygen Delivery Systems Long-term home O 2 therapy is available from three different delivery systems: oxygen concentrators, liquid systems, and compressed gas. Each system has advantages and disadvantages, and the correct system for each patient depends on patient limitations and the clinical application. Oxygen systems were recently compared on the basis of weight, cost, portability, ease of refilling, and availability; the first three factors may be of particular importance in elderly, often debilitated patients. Administration Devices Oxygen is typically administered with continuous flow by a nasal cannula.

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However, because alveolar delivery occurs during a small portion of a spontaneous respiratory cycle (approximately the first sixth), with the rest of the cycle used to fill dead space and for exhalation, the majority of continuously flowing O 2 is not used by the patient and is wasted into the atmosphere. To improve efficiency and increase patient mobility, several devices are available that focus on O 2 conservation and delivery during early inspiration, including reservoir cannulas, demand-type systems, and transtracheal catheters. Reservoir nasal cannulas and pendants store oxygen during expiration and deliver a 20-mL bolus during early inspiration. Because more alveolar O 2 is delivered, flows may be reduced proportionally, resulting in a 2: 1 to 4: 1 O 2 savings at rest and with exercise.

Cosmetic considerations have traditionally limited patient acceptance of these devices. Demand valve systems have an electronic sensor that delivers O 2 only during early inspiration or provides an additional pulse early in inspiration as an adjuvant to the continuous flow.

By restricting or accentuating O 2 during inspiration, wasted delivery into dead space or during exhalation is minimized. This results in a 2: 1 to 7: 1 O 2 savings. The effect of mouth breathing on efficacy is not yet clear. Transtracheal oxygen therapy introduces a thin flexible catheter into the lower trachea for delivery of continuous (or pulsed) O 2. Because O 2 is delivered directly into the trachea, dead space is reduced, and the upper trachea serves as a reservoir of undiluted O 2. This provides a 2: 1 to 3: 1 O 2 savings over a nasal cannula.

However, the widespread use of transtracheal O 2 has been limited by the rate of complications, requiring administration in specialized centers. Oxygen concentrator Most patients will require a stationary source of oxygen which is usually provided by an oxygen concentrator.

Since concentrators are relatively inexpensive and require less frequent home visits than liquid oxygen, they have become the system of choice for suppliers. These electrically powered devices utilize a molecular sieve to separate oxygen from air resulting in delivery of oxygen to the patient, while nitrogen is returned to the atmosphere. The typical sieve achieves oxygen purity of 97% at low flows and 94% at higher flows. However, due to their voltage requirement and their weight, they are primarily a fixed source of oxygen. Consequently, patients need either compressed gas or liquid oxygen as an ambulatory source of oxygen.

New, more portable devices should improve availability of these units. Oxygen Concentrators Improved oxygen availability, independent of compressed gas and electrical power supply, can be provided by linking oxygen concentrators to a draw-over anesthetic apparatus as first described by Fenton. 65 Maintenance requirements are low, and servicing is recommended only after approximately 10,000 hours of usage. The benefits are enormous, but a reliable electricity supply is critical. The concentrator functions by using a compressor to pump ambient air alternately through one of two canisters containing a molecular sieve of zeolite granules that reversibly absorbs nitrogen from compressed air.

63, 78 The controls are simple and comprise an on/off switch for the compressor and a flow-control knob to deliver 0 to 5 L/min. Flow of oxygen continues uninterrupted as the canisters are alternated automatically so that oxygen from one canister is available while the other regenerates. A warning light on a built-in oxygen analyzer illuminates if the oxygen concentration is less than 85% and the concentrator switches off automatically when the oxygen concentration is less than 70%.

This is heralded by visual and audible alarms. Air is then delivered as the effluent gas. Modern machines are relatively silent. The oxygen output of the concentrator depends on the size of the unit, the inflow of oxygen, the minute volume, and pattern of ventilation.

The addition of dead space (or oxygen economizer tube) at the outlet improves the performance, and predictable concentrations of more than 90% oxygen can be obtained with flows between 1 and 5 L/min independent of the pattern of ventilation. Much lower concentrations and less predictability was noted when the dead space tubing was omitted.

80 The possible hazards of oxygen concentrators are few, provided they are positioned in the operating room so that the in-draw area is free from pollutants. Failure of power supply or failure of the zeolite canisters will result in the delivery of ambient air. The Inner Game Of Chess Pdfs more. A bacterial filter at the outlet combined with the use of dust-free zeolite should prevent contamination of the delivered gas. Dirty internal air filters may produce lower oxygen concentrations and must be checked. An oxygen storage tank and booster pumps afford protection against the vagaries in electrical supply. Delivery Systems The oxygen delivery systems available for home use are as follows: compressed gas in high-pressure cylinders; liquid gas in lightweight canisters; and stationary oxygen concentrators.

Large compressed gas cylinders are fixed in place, but patients can move short distances while using long (50-ft) tubing; smaller cylinders can be attached to wheelchairs or installed in automobiles to allow journeys out of the home. Ambulatory patients are best served with a small portable, liquid system, which is the only practicable way to deliver oxygen to someone who is working or active.

Liquid gas-containing canisters and portable oxygen concentrators are constantly being improved to reduce weight and to increase duration of use. Because the goal of pulmonary rehabilitation is to restore the patients' functional capacity to its optimal level and exercise is a fundamental part of pulmonary rehabilitation, every effort must be made to provide hypoxemic patients with portable devices that help achieve these goals. Oxygen Supplemental oxygen therapy is a primary requirement for infants with BPD and CLDI. Oxygen can be provided in the home from compressed gas in tanks, liquid oxygen, or oxygen concentrators. Each system has advantages and disadvantages in terms of the liter flow required, cost, and portability; the system chosen should be based on the needs of the infant as well as the availability of local resources. A proper evaluation of the home environment (e.g., assessment of fire risk and family economic resources) should occur, and the appropriate oxygen source should be established well in advance of discharge. Pulse oximetry may be appropriate and, with careful guidance, can help in the monitoring and management of infants with BPD and CLDI who are chronically hypoxic or who have developed a need for supplemental oxygen.

Pulse oximetry in the absence of home oxygen therapy cannot be recommended. Oxygen saturation is commonly measured during the day. Nocturnal desaturation is frequent, however, and may be unexpected clinically; in addition, nocturnal saturation may correlate poorly with daytime saturation.

36,42 Therefore, overnight oximetry should be performed before nocturnal supplemental oxygen is discontinued. The Traveler's Medical Kit Table 1.7 presents recommendations for a traveler's medical kit for a short-term international trip.

Depending on geographic location(s), type(s) of activities planned, and underlying health, the traveler may augment the kit with regular prescription medications, medication for high-altitude sickness, antifungal preparations, treatment for ectoparasites, and additional antiparasitic drugs. Pulmonary patients may need to make arrangements for portable oxygen supplies and even oxygen concentrator machines, and peritoneal dialysis patients may travel with dialysate fluids and accessories and may need advance reservations for access to dialysis services at the destination (see Chapter 16). Lost 5x02 Ita Download Free.

Prescription Medications At least a few days' supply of necessary medications should be taken in hand-held luggage. Preferably, the entire supply of usual prescription medications, enough to last the whole trip, should be taken in the hand-held luggage. If possible, travelers should not pack their prescription medications in checked luggage, as the baggage could be lost or pilfered in transit. Travelers should not plan to purchase prescription medications abroad as a cost-reducing strategy: expired, improperly stored, and counterfeit drugs are a growing problem worldwide, or the traveler's usual medications may simply not be available. DEVICES AND EQUIPMENT There are various oxygen sources and delivery devices available for use in the home, at work, or in the community. Oxygen may be supplied in gas cylinders of varying sizes.

These cylinders must be replaced or refilled periodically to replenish the oxygen supply and most are large, bulky, and heavy. However, recent technology has made much smaller devices, such as liquid oxygen containers and oxygen concentrators, available ( Fig. These devices can supply oxygen for up to several hours of oxygen, depending on patient usage. Liquid oxygen systems have been available for use at home for many years. There is usually a large reservoir in the home from which a small, portable knapsack–size container may be filled for outside use. Oxygen concentrators, which have also been available for several years, are electrically powered and use a molecular sieve to separate oxygen from the ambient air and concentrate and store the oxygen.

These devices are economical for use in the home and for activities immediately around the house, such as gardening, but are too large to take out into the community. Oxygen must be delivered from its source to the patient via a device. Oxygen catheters may be inserted into the nasal passage or via a small surgical incision directly into the trachea, with a transtracheal device. Oxygen masks placed over the nose and mouth may also be used.

These sometimes have a reservoir that enables high concentrations of oxygen to be provided. The most commonly used device is a nasal cannula that provides a small prong into each nostril for oxygen delivery ( Fig. Mechanical ventilators are commonly used for patients with airway clearance disorders when acute or chronic respiratory failure occurs such as after acute disease processes, trauma, or surgery (see Chapter 26). Basic modes of mechanical ventilation are briefly identified in Table 24-8. When the patient with airway clearance dysfunction is receiving mechanical ventilation, it is important to note the parameters of ventilation, particularly when breathing strategies and retraining are to be employed.

Certain modes and limitations of mechanical ventilation may or may not allow certain breathing strategies. Assistive devices, such as canes and walkers, are often indicated to assist with ambulation and enhance stability and safety. 2 When recommending such assistive devices for the patient with airway clearance dysfunction, the therapist must be aware that crutches, walkers, and similar devices tend to increase the oxygen requirement when compared to unassisted ambulation. 128 A cost-benefit decision about such devices must be made. 129 A wheeled walker can, however, be very helpful for individuals with chronic airway clearance dysfunction. The walker not only offers support and stabilization but with a basket or small platform can be used to carry a small oxygen delivery system during community activities.

Motorized scooters are useful for community mobility outside the home for shopping, work, and recreational activities in individuals with significant airway clearance dysfunction. There are lift systems for automobile storage of the scooters to facilitate patient use. Motorized scooters and the appropriate lift devices are expensive but often make the difference between being housebound or active in the community. The following ventilator options are available: 1. Servo ventilators are used widely around the world but developed primarily for developed nation use. They require a reliable mains power and compressed gas supply. Simpler electromagnetic turbine ventilators have been developed for a wide range of transport and high-dependency unit operations.

Examples include the T Bird (Viays Health Care, Conshohocken, PA) and the Elysee (Saime SA RES MED, Poway, CA). They are of mains/battery operation and do not require a compressed gas supply.

Oxygen is used only for gas enrichment and could be replaced by an oxygen concentrator. Pneumatically operated transport and emergency ventilators could be used in a basic ICU role. Examples include Pneupac Ventipac (Smiths Medical International, Ltd., Kent, UK) and Drager Oxylog 2000 (Drager Siemens, Luebeck, Germany). Mixed pneumatic and electric ventilators require a compressed gas and a mains/battery supply. Examples include the Drager 3000 and Osiris 2 (Taema SA, Cedex, France). Autonomous transport ventilators were originally designed for military use.

Only the Pneupac CompPac 200 (Smith Medical International, Ltd., Kent, UK) fulfills this role at present. It has a wide range of power options including mains/external DC supply/internal battery, which drives an internal compressor. This ventilator has been used in a variety of DN operations including transport and disaster medicine and in use with field anesthesia. Simple and tried bellows ventilators are gas-driven minute volume dividers.

An example is the traditional Manley (Penlon, Ltd., Oxfordshire, UK) ventilator, which is still manufactured and used worldwide. Bellows-type ventilator driven by a gas engine is another option. The driving gas can be either compressed air or oxygen of nonmedical quality because the driving engine is separate from the patient circuit. An example is the Oxford Nuffield Ventilator (Penlon, Ltd.). In general, descent leads to resolution of all forms of altitude illness.

Patients with mild illness may not require descent, however, and often recover by remaining at the same elevation and resting for a period of time. In more severe illness, descent is indicated and should continue until symptoms resolve. How much descent is required varies depending on the severity of the case; less severe illness may resolve with descent of only 300 m while more severe illness may require further drops in altitude. At times, because of field conditions, descent may not be feasible and alternative treatments are necessary.

Severely ill patients can be placed on supplemental oxygen if gas tanks or an oxygen concentrator are available or “low altitude” can be brought to the patient through the use of lightweight portable hyperbaric chambers ( Fig. These chambers can be pressurized to 2 psi and mimic a descent of approximately 1500 m.

By means of a foot pump, sufficient gas flow is maintained to keep the carbon dioxide concentration low and the oxygen concentration close to 21%. 122 Studies demonstrate that the chamber is as effective as administering supplemental oxygen with an F io 2 of 0.26 to 0.3, although the therapy is difficult to implement with claustrophobic individuals or those who are vomiting.

As with oxygen therapy, relief of symptoms is generally immediate, but long treatment times are needed in severe illness and to ensure sustained improvement upon removal from the chamber. 122 Acetazolamide can ameliorate symptoms of AMS and improve arterial oxygenation, 123 while aspirin, 88 ibuprofen, 124 and acetaminophen 124 have been shown to treat the headache associated with AMS. Prochlorperazine is useful for treating nausea and vomiting and, unlike some other antiemetics, may actually increase rather than depress ventilation. 125 Even if it is not being used for AMS prophylaxis, dexamethasone should be part of the high-altitude traveler's medical kit, especially in remote areas of the mountains, because rapid treatment of evolving symptoms with dexamethasone may keep the patient ambulatory, allowing a rapid descent without need for an expensive evacuation.

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