What is a Hyperbaric Stretcher?+
A hyperbaric stretcher is a folding portable pressure vessel suitable for the pressurisation and transport under pressure of a person requiring hyperbaric oxygen therapy (HBO). It is rigid when inflated, but when not in use, can be packed away for easy portability.
What is the purpose of a Hyperbaric Stretcher?+
The presence of a hyperbaric stretcher at an accident or emergency site enables a casualty requiring hyperbaric oxygen therapy (HBO) to be treated as soon as the first symptoms of the requirement become apparent. The importance of immediate treatment of diving accidents cannot be over-emphasised. Delay in treatment greatly reduces the likelihood of full resolution.
Due to the lightness and portability of a hyperbaric stretcher, it is almost always possible to have a unit on site, irrespective of the whereabouts of the incident, whereas to have a larger therapeutic chamber available on site is often logistically not possible.
Note: 1 bar = 5 msw = 33 fsw. At sea level the pressure is 1 atmosphere absolute (ATA) which is just over 1 bar (1.3% over). Chamber/stretcher pressures in hyperbarics are usually measured in metres (or feet) seawater and are assumed to be above 1 atmosphere, ie the depth of seawater. Remember that with a hyperbaric stretcher, you may not be at sea level and therefore it is more correct to consider absolute pressures when referring to therapies.
To what pressure does a hyperbaric stretcher need to be capable of operating?+
A hyperbaric stretcher should be capable of operating to a pressure of at least 1.8 bars above ambient pressure. Above 3 bars absolute pressure (2 bars above atmospheric pressure at sea level), pure oxygen becomes toxic very quickly. Furthermore, at 3 bars absolute pressure or above, one cannot remove the patient from the hyperbaric stretcher in an emergency, without life threatening consequences.
Are higher pressures never required in the treatment of diving accidents?+
Initial treatment therapies for diving accidents are normally conducted at 2.8 bars absolute. If resolution does not take place, then the patient may be subjected to higher pressures when transferred into a therapy chamber where full hands-on medical care is available.
Why does the Hyperlite have a maximum working pressure of 23msw (75 fsw)?+
When the Hyperlite is used in reduced atmospheres, such as in an aircraft or at altitude, then the differential pressure between the inside and outside of the hyperbaric stretcher may exceed 1.8bar (18msw, 60fsw), the most common treatment pressure for pressure related illnesses. This has been allowed for in the design of the hyperbaric stretcher.
Some chambers have a flange attachment so that they may be mated to a therapy chamber? Does the Hyperlite stretcher have such a flange?+
The Hyperlite has been designed with a maximum diameter 585 mm 23 in, small enough to enable it to pass directly through the door of almost any therapy chamber and therefore not need to be locked-on.
What tests have been carried out to prove the Hyperlite's durability?+
The hyperbaric stretcher has been subjected to the following tests: 1. Hydrostatic Proof Pressure Tests Three prototype hyperbaric stretchers maintained total integrity at 6 times maximum working pressure (201psi, 139msw, 455fsw) for a period of 30 minute at max. operating temperature. 2. Drop Tests The hyperbaric stretcher was set up with a 90 kg (200 lb) mannequin on the drag mattress. After pressurisation it was suspended at 45 degrees to the horizontal and dropped a distance of 3 feet on to a rough concrete surface. No damage or pressure loss took place. 3. Cyclic Hydrostatic Pressure Test The hyperbaric stretcher was cycled 11,000 times from atmospheric to maximum working pressure without damage or failure. 4. Folding Tests, Hot and Cold Storage and Inflation Tests, Solar Radiation, Salt Fog Resistance, Vibration Tests, Offgassing Toxicity Tests and Extended Duration Creep Tests have all been successfully tested by Lloyd's Register EMEA, by the UK MoD and/or by the Wyle Laboratories on behalf of the US DoD.
To what Quality Standard are Hyperlite's built?+
All Hyperlite's are built to the BS EN ISO 13485:2003 Quality Standard, covering both design and manufacture. It is also CE marked under the Medical Device Directive 93/42/EEC and Health Canada approved.
Is the Hyperlite supplied with a warranty?+
The Hyperlite is supplied with a full one-year warranty covering materials and workmanship. Each hyperbaric stretcher is built to Lloyd's Register Rules and Regulations and to the ASME PVHO-1 US National Standard (2007). It is a requirement that training be given to Hyperlite Operators. Use by unqualified personnel may invalidate the Warranty
How is the Hyperlite tested prior to delivery?+
In addition to quality control and visual inspections at all stages of manufacture, each Hyperlite is pressurised to 1.5 times the maximum working pressure for one hour. All testing may be witnessed by the purchaser's representative.
How is the Hyperlite protected from over-pressurisation?+
The Hyperlite has an emergency blow-off valve set at 26 msw (86 few).
How do you ensure that the operator does not make wrong connections when assembling the Hyperlite?+
Each connection is different, either in size or type and is colour-coded, so that no hose can be wrongly connected.
What material is used in the manufacture of the flexible tube to make it so strong and yet be so flexible?+
The Hyperlite flexible tube is made of braided Vectran Liquid Crystal Polymer fibres enclosed on both sides by Polyurethane (PU) coated fabrics. The pressure retaining bladder on the inside is a white coated nylon and on the outside is a coated polyester cover (available in various designs).
Does the integrity of the Hyperlite tube suffer damage by folding?+
The tube is unlikely to suffer damage from repeated folding during its normal working life. A prototype tube assembly has undergone 4000 folding and unfolding tests.
Does the Hyperlite tube suffer from being kept folded in its storage case?+
No, The manufacturer recommends however that the hyperbaric stretcher be removed every six months for a trial inflation.
Does the Hyperlite tube suffer from the effects of high or low temperature?+
The Hyperlite tube is approved for use between -20*C and 40*C (-4*F to 54*F). For storage, the tube shall be kept between -23*C (-5*F) and 66*C (150*F). For patient comfort, the Hyperlite should ideally be kept below 29*C (84*F) when in service.
Can repairs be made to a damaged Hyperlite tube?+
Yes, the tube assemblies can be repaired, but only by certified technicians at an approved repair facility
Can a patient be X-rayed inside the hyperbaric stretcher?+
By positioning the tube above the hyperbaric stretcher and the plate beneath the hyperbaric stretcher, any part of a patient can be X-rayed without loss of clarity. The intensity of dosage should not need to be increased.
Can the Hyperlite be used and carried at much lower pressures?+
It remains rigid and fully operational at pressures down to 5 msw (16 few).
Does the Hyperlite float?+
The Hyperlite will always remain buoyant when inflated, even with a large heavy casualty and all the services connected.
Could a patient suffer from claustrophobia in such a small unit?+
This is unlikely as the Hyperlite is supplied with two full diameter transparent domes giving the patient excellent vision from the unit.
How much air and oxygen is needed for a therapy?+
This will depend upon the pressures to which the Hyperlite will be are the responsibility of the operator and can easily be calculated.
Is patient monitoring possible inside the Hyperlite?+
Provided that the unit has been supplied with the correct penetrations and connections, full monitoring of the patient including ECG (EKG), EEG, BP, Pulse Oximetry, and IV sampling etc. are all possible. There is the added capability, using the TeleMedic Systems Vitalink³ Monitoring System, of being able to transmit the information electronically in real time to anywhere in the world via the internet.
What happens if the condition of the casualty deteriorates and a 'hands-on' situation becomes vital?+
This is a situation where the patient must be removed from the Hyperlite without delay. This can be done by fully opening the emergency vent in addition to the pressure exhaust valve. Even from maximum operating pressure, the patient can be de-pressurised in little over one minute.
If removal of a diving casualty from the Hyperlite becomes essential, will the return to ambient pressure bring back the 'bends'?+
Provided that the patient has been under pressure on oxygen for some time, it may well be that the nitrogen has already been flushed out of the system and the symptoms are unlikely to recur. The patient should however be re-pressurised as soon as possible.
Can the Hyperlite be carried on scheduled airlines or chartered aircraft?+
IATA regulations permit the carriage of the Hyperlite with a casualty aboard aircraft in emergency circumstances subject only to agreement with the Carrier. There are no formal restrictions concerning the carriage of air and oxygen cylinders for life support purposes in this situation.
Does the Hyperlite suffer from off-gassing?+
The PU coated nylon used for the Hyperlite Bladder has been selected for its low offgassing properties. The same material is used in other life support breathing equipment.