While increasing tissue-oxygen levels is a primary therapeutic effect of HBOT, other benefits include reducing edema, modifying growth factors and cytokine effects, stimulating more rapid development of capillary budding and granulation tissue formation within the wound bed, promoting cellular proliferation, accelerating collagen deposition, and increasing microbial oxidative killing.

Damaged tissue can have decreased oxygen levels that reduce the activity of several antibiotics, including aminoglycosides, sulfonamides, and fluoroquinolones. By raising the oxygen in ischemic tissue to normal levels, HBOT may normalize the activity of these antimicrobials. Additionally, HBOT may potentiate the activity of certain antimicrobials by inhibiting biosynthetic reactions in bacteria. HBOT can modulate the immune system response and also enhance oxygen-radical scavengers, thereby decreasing ischemia-reperfusion injury.

Although any therapeutic application of hyperbaric oxygenation is intrinsically associated with the potential for producing mild-to-severe side effects, the appropriate use of hyperoxia is one of the safest therapeutics available to the practitioner.

It is unknown if hyperbaric oxygen therapy will cause congenital defects in horses. In human studies it has not been shown to have adverse effects. In our hyperbaric center, we do not hesitate to treat a mare with HBOT, especially when the benefits outweigh the risks. It is not unusual in our clinic, if treating a foal, to allow the mare in the chamber during treatments to aid in the relaxation of the foal.

Once the critical level of oxygen is determined, oximetry may be used to adjust oxygen flow settings over time (see Symptoms and Diagnosis of Lung Disorders: Arterial Blood Gas (ABG) Analysis). Oximetry is painless and uses a simple device that is attached to a finger or ear to measure the concentration of oxygen in the blood.

Oxygen for long-term home use is available from three different delivery systems: electrically driven oxygen concentrators, liquid systems, and compressed gas. Inside the home, liquid and compressed gas systems use large tanks to store oxygen. Small, portable tanks of compressed oxygen also may be needed for brief periods—a few hours—outside the home. Each system has advantages and disadvantages.

Oxygen is typically administered with continuous flow through a two-pronged nasal tube (cannula), even though this system is highly wasteful of oxygen. To improve efficiency and increase the person’s mobility, several devices, including reservoir cannulas, demand-type systems, and transtracheal catheters, can be used. Usually, a respiratory therapist or physician instructs the person about proper oxygen use.

While using oxygen therapy at home, it is important to stabilize the tank (possibly using a stand) and store it in an area that is out of the way so it will not fall. Tanks should be closed tightly when not in use. Because oxygen can cause an explosion, it is also important to keep tanks away from any flammable source, such as matches, heaters, or hair dryers. No one in the house should smoke when oxygen is in use.

Several therapeutic principles are made use of in HBOT:

* The increased overall pressure is of therapeutic value when HBOT is used in the treatment of decompression sickness and air embolism.
* For many other conditions, the therapeutic principle of HBOT lies in a drastically increased partial pressure of oxygen in the tissues of the body. The oxygen partial pressures achievable under HBOT are much higher than those under breathing pure oxygen at normobaric conditions (i.e. at normal atmospheric pressure).
* A related effect is the increased oxygen transport capacity of the blood. Under atmospheric pressure, oxygen transport is limited by the oxygen binding capacity of hemoglobin in red blood cells and very little oxygen is transported by blood plasma. Because the hemoglobin of the red blood cells is almost saturated with oxygen under atmospheric pressure, this route of transport cannot be exploited any further. Oxygen transport by plasma, however is significantly increased under HBOT.

Uses

The United States, the Undersea and Hyperbaric Medical Society, known as UHMS, approved for reimbursement diagnoses for application of HBOT in hospitals. The following indications are approved uses of hyperbaric oxygen therapy as defined by the UHMS Hyperbaric Oxygen Therapy Committee.

* Air or gas embolism
* Carbon monoxide poisoning
o Carbon Monoxide Poisoning Complicated by Cyanide Poisoning
* Clostridal Myositis and Myonecrosis (Gas gangrene)
* Crush Injury, Compartment syndrome, and other Acute Traumatic Ischemias
* Decompression sickness
* Enhancement of Healing in Selected Problem Wounds
* Exceptional Blood Loss (Anemia)
* Intracranial Abscess
* Necrotizing Soft Tissue Infections (Necrotizing fasciitis)
* Osteomyelitis (Refractory)
* Delayed Radiation Injury (Soft Tissue and Bony Necrosis)
* Skin Grafts & Flaps (Compromised)
* Thermal Burns

In the United States, HBOT is recognized by Medicare as a reimbursable treatment for 14 UHMS “approved” conditions. An HBOT session costs anywhere from $100 to $200 in private clinics, to over $1,000 in hospitals. U.S. physicians may lawfully prescribing HBOT for “off-label” conditions such as Lyme Disease, stroke and migraines. Such patients are treated in outpatient clinics. In the United Kingdom most chambers are financed by the National Health Service, although some, such as those run by Multiple Sclerosis Therapy Centres, are non-profit.

Other reported applications include:

* Diabeticaly derived illness, such as diabetic foot, diabetic retinopathy, diabetic nephropathy
* Epidural abscesses
* Certain kind of hearing loss
* Radiation-induced hemorrhagic cystitis
* Inflammatory bowel disease

HBOT is controversial and health policy regarding its uses is politically charged. Both sides of the controversy on the effectiveness of HBOT is available in the form of Cochrane Library reviews.

Structure

Traditional

The traditional type of hyperbaric chamber used for HBOT is a hard shelled pressure vessel. Such chambers can be run at absolute pressures up to 600 kilopascals or 85 PSI (lbf/in²), nearly six atmospheres.

Navies, diving organizations and hospitals typically operate these. They range in size from those which are portable and capable of treating just one patient to those which are fixed, very heavy and capable of treating eight or more patients.

The chamber may consist of:

* a pressure vessel that is generally made of steel and aluminium with the view ports (windows) or hull made of acrylic.
* one or more human entry hatches—these could be small and circular or wheel-in type hatches for patients on trolleys
* an airlock allowing human entry—a separate chamber with two hatches, one to the outside world and one to the main chamber, which can be independently pressurized to allow patients to enter or exit the main chamber while it is still pressurized
* an airlock allowing medicines, instruments and food to enter the main chamber
* glass ports or closed-circuit television allowing the technicians and medical staff outside the chamber to monitor the inside of the chamber
* an intercom allowing two-way communications inside and outside the chamber
* a carbon dioxide scrubber—consisting of a fan that passes the gas inside the chamber through a soda lime canister
* a control panel outside the chamber is used to open and close valves allowing air to enter or leave the chamber and oxygen to be supplied to oxygen helmets or masks

Oxygen breathing

Breathing 100% oxygen from an aviators’ oxygen mask.
A recompression chamber for a single diving casualty

In today’s larger “multiplace” chambers, both patients and medical staff inside the chamber breathe from “oxygen helmets”, flexible, transparent soft plastic helmets with a seal around the neck similar to a space suit helmet, or tightly fitting aviators oxygen masks, which supply pure oxygen and remove the exhaled gas from the chamber. During treatment patients breathe 100% oxygen most of the time but have periodic air breaks to minimize the risk of oxygen toxicity. The exhaled gas must be removed from the chamber to prevent the build up of oxygen, which could provoke a fire. Medical staff may also breathe oxygen to reduce the risk of decompression sickness. Administration of 100% breathing oxygen maximizes the patient’s treatment. The pressure inside the chamber is increased by opening valves allowing high-pressure air to enter from storage cylinders, similar to diving cylinders. A gas compressor is used to fill these cylinders.

Smaller “monoplace” chambers can only accommodate the patient. No medical staff can enter. The chamber is flooded with pure oxygen or compressed air. The cost of using pure oxygen in a monoplace chamber is much higher than using compressed air. If pure oxygen is used no oxygen breathing mask or helmet is needed. If compressed air is used then an oxygen mask or helmet is needed as in a multiplace chamber. In monoplace chambers that are compressed with pure oxygen a mask is available to provide the patient with “air breaks,” periods of breathing normal air, in order to reduce the risk of hyperoxic seizures.

Effects of Pressure

Patients inside the chamber will notice discomfort inside their ears as a pressure difference develops between their middle ear and the chamber atmosphere. This can be relieved by the Valsalva maneuver or by “jaw wiggling”. As the pressure increases further, mist may form in the air inside the chamber and the air may become warm. When the patient speaks, the pitch of the voice may increase to the level that they sound like cartoon characters.

To reduce the pressure, a valve is opened to allow gas out of the chamber. As the pressure falls, the patient’s ears may “squeak” as the pressure inside the ear equalizes with the chamber. The temperature in the chamber will fall.

Home treatment

There are portable HBOT chambers, which are used for home treatment. These are usually referred to as “mild chambers”, which is a reference to the lower pressure of soft-sided chambers. Those commercially available in the USA go up to 4 PSI (1.27 ATA 8.92 FSW). International portable chambers can go to 7.35 psi (1.5 ATA 16.38 FSW) or higher. These chambers are operated with oxygen concentrators (typically 95% oxygen) or with 100% oxygen as the breathing gas. Total concentration of oxygen should not exceed 25% as this can increase the risk of fire.

These chambers are often used in a clinical settings, but are also used in homes. Mild hyperbaric chambers use standard 120 volt outlets and can also be configured for 220 volt use. Ranging in size from 21″ up to 40″ in diameter these chambers measure between 84″ to 120″ in length. The soft chambers are FDA approved only for the treatment of altitude sickness but are commonly used off label primarily for the treatment of autism and other neural conditions though there is no proof that it is effective and hospitals refuse to allow their chambers to be used for this purpose. The FDA has a specific warning that supplemental oxygen is not to be used.

Treatments

Initially, HBOT was developed as a treatment for diving disorders involving bubbles of gas in the tissues, such as decompression sickness and gas embolism. The chamber cures decompression sickness and gas embolism by increasing pressure, reducing the size of the gas bubbles and improving the transport of blood to downstream tissues. The high concentrations of oxygen in the tissues are beneficial in keeping oxygen-starved tissues alive, and have the effect of removing the nitrogen from the bubble, making it smaller until it consists only of oxygen which is then re-absorbed into the body. After elimination of bubbles, the pressure is gradually reduced back to atmospheric levels.

Protocol

The slang term for a cycle of pressurization inside the HBOT chamber is “a dive”. An HBOT treatment for longer-term conditions is often a series of 20 to 40 dives.

Emergency HBOT for diving disorders typically follows one of two forms. For most cases, a shallow “dive” to a pressure the equivalent of 18 meters / 60 feet of water for 3 to 4.5 hours with the casualty breathing pure oxygen with air breaks every 20 minutes to reduce oxygen toxicity. For extremely serious cases, a deeper “dive” to a pressure the equivalent of 37 meters / 122 feet of water for 4.5 hours with the casualty breathing air.

In Canada and the United States, the U.S. Navy Dive Charts are used to determine the duration, pressure and breathing gas of the therapy. The most frequently used tables are Table 5 and Table 6. In the UK the Royal Navy 62 and 67 tables are used.

The Undersea and Hyperbaric Medical Society[57] (UHMS) publishes a report which compiles the latest research findings and contains information regarding the recommended duration and pressure of the longer-term conditions.

Possible complications

There are risks associated with HBOT, similar to some diving disorders. Pressure changes can cause a “squeeze” or barotrauma in the tissues surrounding trapped air inside the body, such as the lungs[58], behind the eardrum[59][60], inside paranasal sinuses[59], or trapped underneath dental fillings[61]. Breathing high-pressure oxygen for long periods can cause oxygen toxicity. Temporarily blurred vision can be caused by swelling of the lens, which usually resolves in two to four weeks.[62][63]

There are reports that cataract may progress following HBOT.[64] Also a rare side effect has been blindness secondary to optic neuritis (inflammation of the optic nerve).[citation needed]

Contraindications

The only absolute contraindication to hyperbaric oxygen therapy is untreated pneumothorax.[65] Also, the treatment may raise the issue of Occupational safety and health (OHS), which has been encountered by the therapist.[66][clarification needed]

Patients should not undergo HBO therapy if they are taking or have recently taken the following drugs:

* Doxorubicin (Adriamycin) – A chemotherapeutic drug.
* Disulfiram (Antabuse) – Used in the treatment of alcoholism.
* Cis-platinum – A cancer drug.
* Mafenide acetate (Sulfamylon) – Suppresses bacterial infections in burn wounds

The following are relative contraindications:

* Upper respiratory infections – These conditions can make it difficult for the patient to clear their ears, which can result in what is termed sinus squeeze.
* High fevers – In most cases the fever should be lowered before HBO treatment begins.
* Emphysema with CO2 retention – This condition can lead to pneumothorax during HBO treatment.
* History of thoracic (chest) surgery – This is rarely a problem and usually not considered a contraindication. However, there is concern that air may be trapped in lesions that were created by surgical scarring. These conditions need to be evaluated prior to considering HBO therapy.
* Malignant disease: Since cancers both thrive in blood rich environments and may be suppressed in high oxygen environments, cancer and HBO poses a dilemma since HBO both increases blood flow via angiogenesis and also raises oxygen levels. Taking an anti-angiogenic supplement may provide a solution to this problem.
* Middle ear barotrauma (MEBT) is always a consideration in treating both children and adults in a hyperbaric environment, but most children currently being treated with HBOT are being pressurized to 1.3 ATA which reduces the risks of potential side effects.

Neuro-rehabilitation
The Collet (Quebec) trial that was published in the Lancet in 2001 was the largest randomized trial of Hyperbaric Oxygen Therapy (HBOT) for children with cerebral palsy (CP); it followed the McGill pilot study on the same subject.

The evidence showed both groups of children treated with two very different hyperbaric treatment dosages improved significantly. The motor improvements that were seen and measured with the gross motor function measure were greater, more generalized, and were obtained in a shorter period of time than most of the changes found in any other studies of recognized conventional therapies in the treatment of children with cerebral palsy. The children in both groups improved an average of ten times more during the two months of HBOT (whilst all other therapies and medication were stopped) than during the three months follow-up (when medication and all the ancillary treatments were restarted). This impressive change in the rate of improvements clearly indicates the probable effectiveness of hyperbaric treatment. Both the Lancet commentary and the tech report by the Agency for Healthcare Research and Quality (AHRQ) concluded that the hypothesis of both treatments being equally effective should be retained.

Since the Quebec study of HBOT for children with CP, many reports have been made on the possible efficacy of a low pressure hyperbaric treatment and all the trials conducted with HBOT in CP have demonstrated positive results.

An editorial on CP published by the Undersea and Hyperbaric Medical Society in 2007 called for further research that will include “basic science research to determine a reasonable mechanism of action” for hyperbaric oxygenation as well as “clinical studies of the highest possible methodological rigor”.

Some medical practitioners recommend the use of HBOT for the treatment of acute tinnitus but this treatment has not been verified by independent evidence and the treatment was withdrawn from support by the German health insurance. There is evidence that the therapeutic effects could be greatly due to psychological mechanisms triggered by the patients attitude towards therapy prior to the treatment.

The earliest randomized, placebo-controlled, double-blind study on multiple sclerosis patients treated with HBOT suggested the therapy could improve balance and bladder function. However, by 2004 a Cochrane review assessing ten trials and 21 analyses “found no consistent evidence to confirm a beneficial effect of hyperbaric oxygen therapy for the treatment of multiple sclerosis and do not believe routine use is justified.

For more informaton on Hyperbaric Chambers

Oxygen first aid specifically refers to the use of oxygen in a first aid setting. Oxygen will assist patients with myocardial infarction and hypoxia (low blood oxygen levels). Care needs to be exercised in patients with chronic obstructive pulmonary disease, especially in those known to retain carbon dioxide (type II respiratory failure) who lose their respiratory drive and accumulate carbon dioxide if administered oxygen in moderate concentration. However the risk of the loss of respiratory drive are far outweighed by the risks of withholding emergency oxygen, and therefore emergency administration of oxygen is never contraindicated.

Home or domiciliary oxygen therapy

This refers to the administration of oxygen as ongoing therapy, either continuously or intermittently. Most commonly patients on home oxygen therapy have severe chronic obstructive pulmonary disease caused by smoking. High concentration (approaching 100%) oxygen is used as home therapy to abort cluster headache attacks, due to its vaso-constrictive effects.[1] It is indicated in COPD patients with PaO2 ≤ 55mmHg or SaO2 ≤ 88% and has been shown in a Medical Research Council study to increase survival.

Oxygen sources and delivery
Gas canisters containing oxygen to be used at home. When in use a pipe is attached to the top of the can and then to a mask that fits over the patient’s nose and mouth.
A home oxygen concentrator in situ in an Emphysema patient’s house. The model shown is the DeVILBISS LT 4000.

There are three typical sources of oxygen used therapeutically:

1. Liquid oxygen is contained in thermally insulating tanks. The liquid has to boil changing into a gas for breathing. Large tanks are used by hospitals. Small tanks can be used domestically. Liquid oxygen tanks are refilled by liquid oxygen suppliers.

2. Cylinders contain compressed gaseous oxygen. Small cylinders are used for first aid and for home oxygen patients when mobility is required. Cylinders are refilled by a gas supplier.

3. Oxygen concentrators are electrically powered devices which remove nitrogen from air. They are most commonly used in a domestic situation, because they do not need refilling. However, a number of manufacturers have introduced portable oxygen concentrators. These have replaced[2] the need to use liquid or gas cylinders for mobility for many patients. Portable Oxygen Concentrators allow patients to freely travel without the need of gas or liquid. The FAA has approved portable oxygen concentrators for the use on many commercial airlines. Most major airlines allow the three major portable oxygen concentrators; it is necessary to check in advance if a particular brand or model is permitted on a particular airline. These can typically use AC, DC, or battery power. Some portable concentrators have only pulse or demand flow capabilities, while continuous flow portables are available. Pulse or demand flow is similar to the way an oxygen conserving device delivers oxygen from liquid oxygen or a gas cylinder only during inhalation, but on a concentrator, the oxygen made in between pulses is stored for the next pulse. Where a conserving device can make a liquid or gas container last longer, pulse or demand settings on oxygen concentrators can make a certain flow appear as a higher effective flow, or reduce power consumption and/or extend battery life.

First aid kits have been produced that create oxygen gas as the result of a chemical reaction between lightweight or widely available substances such as sodium percarbonate and water, although the rate and duration of oxygen supply is not high.

Oxygen is most often delivered as continuous gaseous flow, measured in litres per minute (lpm).

Low-Flow Devices

Low-flow systems deliver oxygen at flows that are less than the patient’s inspiratory flowrate (ie, the delivered oxygen is diluted with room air) and, thus, the oxygen concentration inhaled may be low or high, depending on the specific device and the patient’s inspiratory flowrate.

1. The nasal cannula (NC) is a thin tube with two small nozzles that protrude into the patients nostrils. It can only comfortably provide oxygen at low flow rates, 0.25-6 litres per minute (LPM), delivering a concentration of 24-40%. Flow rates greater than 4 liters per minute can cause discomfort and dry out the nasal passages and should also be used with a humidifcation system.

2. The simple face mask (SFM) is a basic mask used for non-life-threatening conditions but which may progress in time, such as chest pain (possible heart attacks), dizziness, and minor hemorrhages. It is often set to deliver oxygen between 5-15 LPM. The final oxygen concentration delivered by this device is dependent upon the amount of room air that mixes with the oxygen the patient breathes. The general oxygen concentration is between 35% and 50%

1. The Partial rebreathing mask is a simple mask with a reservoir bag. Oxygen flow should always be supplied to maintain the reservior bag at least one third to one half full on inspiration, usually 5-15 LPM. At a flow of 6-10 L/min the system can provide 40-70% oxygen.

High-Flow Devices

High-flow systems deliver a prescribed gas mixture — either high or low FDO2 at flowrates that exceed patient demand.

1. The non-rebreather mask (NRB) is similar to the partial rebreathing mask except it has a series of one-way valves. One valve is placed between the bag and the mask to prevent exhaled air from returning to the bag. There should be a minimum flow of 10 L/min. The delivered FIO2 of this system is 60-80%, depending on the oxygen flow and breathing pattern.

1. Air-entrainment masks, also known as Venturi masks, can accurately deliver predetermined oxygen concentration to the trachea up to 40%. Jet-mixing masks rated at 35% or higher usually however do not deliver flowrates adequate to meet the inspiratory flowrates of adults in respiratory distress. Aerosol masks, tracheostomy collars, T-tube adapters, and face tents can be used with high-flow supplemental oxygen systems. A continuous aerosol generator or large-volume reservoir humidifier can humidify the gas flow. Some aerosol generators however, cannot provide adequate flows at high oxygen concentrations.

Filtered Oxygen Masks

Filtered oxygen masks have the ability to prevent exhaled, potentially infectious particles from being released into the surrounding environment. These masks are normally of a closed design such that leaks are minimized and breathing of room air is controlled through a series of one-way valves. Filtration of exhaled breaths is accomplished either by placing a filter on the exhalation port, or through an integral filter that is part of the mask itself. These masks first became popular in the Toronto (Canada) healthcare community during the 2003 SARS Crisis. SARS was identified as being respiratory based and it was determined that conventional oxygen therapy devices were not designed for the containment of exhaled particles. Common practices of having suspected patients wear a surgical mask was confounded by the use of standard oxygen therapy equipment. In 2003, the HiOx80 oxygen mask was released for sale. The HiOx80 mask is a closed design mask that allows a filter to be placed on the exhalation port. Several new designs have emerged in the global healthcare community for the containment and filtration of potentially infectious particles. Other designs include the ISO-O2 oxygen mask,the Flo2Max oxygen mask, and the O-Mask. The use of oxygen masks that are capable of filtering exhaled particles is gradually becoming a recommended practice for pandemic preparation in many jurisdictions.

Because filtered oxygen masks use a closed design that minimizes or eliminates inadvertent exposure to room air, delivered oxygen concentrations to the patient have been found to be higher than conventional non-rebreather masks, approaching 99% using adequate oxygen flows. Because all exhaled particles are contained within the mask, nebulized medications are also prevented from being released into the surrounding atmosphere, decreasing the occupational exposure to healthcare staff and other patients.

Resuscitation/Specialized Devices

1. The bag-valve-mask (BVM) is used for patients in critical condition who are either breathing extremely inefficiently, or not breathing at all (respiratory arrest). An oxygen reservoir bag is attached to a central cylindrical bag, attached to a valved mask that administers almost 100% concentration oxygen at 8-15 lpm. The central bag is squeezed manually to deliver a “breath” to the patient, or assist them in inspiration by overcoming airway resistance or thoracic constriction. This is the standard administration method for acute respiratory distress or respiratory arrest.

2. The pocket mask is a small device that can be carried on one’s person. It is used for the same patients who the BVM is indicated for, but instead of delivering breaths by squeezing a reservoir, the care provider must exhale into the mask. Exhaled air from the provider can provide up to 16% oxygen to the patient, or higher if used with supplemental oxygen.

3. The anaesthetic machine is a machine used during anesthesia that allows a variable amount of oxygen to be delivered, along with other gases including air, nitrous oxide and inhalational anaesthetics.

4. Aviator type and other specialized tight fitting oxygen masks are used in hyperbaric oxygen chambers and to provide oxygen to carbon monoxide victims.

Related devices

1. A pressure regulator is used to control the high pressure of oxygen delivered from a cylinder to a low pressure controllable by the flowmeter.

2. A flowmeter is used to control and indicate the flow of oxygen. Typiclal flow range is 0-15 lpm.

3. A nebulizer can be used deliver nebulizable drugs such as albuterol or epinephrine into the airways by creating a vapor-mist from the liquid form of the drug. Nebulizers are also commonly used with room air in the home with an electric air pump.

Negative effects

Although most EMS jurisdictions hold that oxygen should not be withheld from any patient, there are certain situations in which oxygen therapy can have a negative impact on a patient’s condition.

Oxygen has vasoconstrictive effects on the circulatory system, reducing peripheral circulation and was once thought to potentially increase the effects of stroke. However, when additional oxygen is given to the patient, additional oxygen is dissolved in the plasma according to Henry’s Law. This allows a compensating change to occur and the dissolved oxygen in plasma supports embarrassed (oxygen-starved) neurons, reduces inflammation and post-stroke cerebral edema. Since 1990, hyperbaric oxygen therapy has been used in the treatments of stroke on a worldwide basis. In rare instances, hyperbaric oxygen therapy patients have had seizures. However, because of the afformentioned Henry’s Law effect of extra available dissolved oxygen to neurons, there is usually no negative sequel to the event. Such seizures are thought to be caused by hypoglycemia and the risk can be eradicated or reduced by carefully monitoring the patient’s nutritional intake prior to oxygen treatment.

Some jurisdictions require that oxygen should not be given to children or people suffering from certain long-term lung conditions by first-responders without medical consultation.

Oxygen first aid has been used as an emergency treatment for diving injuries for years. The success of recompression therapy as well as a decrease in the number of recompression treatments required has been shown if first aid oxygen is given within four hours after surfacing. There are suggestions that oxygen administration may not be the most effective measure for the treatment of DCI/DCS and that Heliox may be a better alternative. Recompression in a hyperbaric chamber with the patient breathing 100% oxygen is the standard hospital and military medical response to decompression illness and decompression sickness.

Oxygen should never be given to a patient who is suffering from paraquat poisoning unless they are suffering from severe respiratory distress or respiratory arrest, as this can increase the toxicity. (Paraquat poisoning is rare – for example 200 deaths globally from 1958-1978).

Oxygen therapy while on aircraft

In the United States, most airlines restrict the devices allowed on board aircraft. As a result passengers are restricted in what devices they can use. Some airlines will provide cylinders for passengers with an associated fee. Other airlines allow passengers to carry on approved portable concentrators. However the lists of approved devices varies by airline so passengers need to check with any airline they are planning to fly on. Passengers are generally not allowed to carry on their own cylinders. In all cases, passengers need to notify the airline in advance of their equipment.

The study shows that those patients who complained of nightmares during the week following the suicide attempt were three times more likely to attempt to take their own life again, regardless of gender or psychiatric diagnosis, such as depression or post-traumatic stress syndrome.

“Those who were still suffering from nightmares after two months faced an even greater risk. These people were five times more likely to attempt suicide a second time,” says author of the thesis, Registered Nurse Nils Sjöström.

Other sleeping difficulties do not increase risk of repeat suicide attempts

It is normal for patients that have attempted suicide to suffer from sleeping difficulties. Some 89 percent of the patients examined reported some kind of sleep disturbance. The most common problems were difficulty initiating sleep, followed by difficulty maintaining sleep, nightmares and early morning awakening. Nils Sjöström has also examined the possibility of there being an increased risk of repeat suicide attempts if the patient has difficulty falling asleep, difficulty sleeping during the night, or wakes up early in the morning. However, the result did not indicate any increased risk.

“The results show how important it is for healthcare staff to highlight the significance of nightmares in the clinical suicide risk assessment,” says Nils Sjöström.

“They said that I had 35 interruptions of my sleep per hour. So that meant that I was never getting fully asleep,” says Lou.

Because he was deprived of oxygen at night, Lou’s heart was being damaged, which is why he started using a continuous positive airway pressure mask, or a C-PAP mask. Doctors have known for sometime that it helps patients breathe better.

“What we haven’t known as well, is, whether or not C-PAP benefits the heart,” says Doctor Subha Raman, MD at the Ohio State University Medical Center.

So doctors at the Ohio State University Medical Center decided to find out. They took MRI’s of patients to get a good idea of the size and shape of their hearts when they were first diagnosed. Then patients were given C-PAP masks to sleep in. After several weeks they came back for another MRI, and doctors were surprised by what they saw.

“We saw that before treatment, the heart was enlarged. But after three months of careful use of their CPAP, we saw a reduction in the enlargement of the heart,” says Dr. Raman.

In all, experts say of the 13 patients who tried it, there were “significant” changes in the right ventricle of the heart.* Which means this mask not only helps with sleep disorders, but may be helping doctors get to the heart of a much more serious problem, as well.

Doctors say if left untreated, sleep apnea can lead to high blood pressure, and increase your risk of diabetes or having a stroke. If someone complains that you snore loudly and often you may want to get checked out by your doctor.

Experts say that poor air quality and ventilation is partly due to economies made by airlines to reduce fuel costs and extend the working life of aircraft.

In the study, a team of Belfast researchers measured oxygen saturation levels – the amount of oxygen carried in the blood.

Before take-off, levels averaged 97 per cent but these fell to 93 per cent at altitude.

For 54 per cent of travellers, the fall in oxygen levels was at least 6 per cent – a level at which many hospital doctors would prescribe extra oxygen.

The results were similar for both short-haul and long-haul fliers, according to the research published in Anaesthesia, the official journal of the Association of Anaesthetists of Great Britain and Ireland.

The 84 passengers who took part in the tests were aged between one and 78. None had severe cardio-respiratory problems and no one required permission from their doctor to fly.

Dr Susan Humphreys, anaesthetic specialist registrar, said research showed that a drop in oxygen levels in the blood can lead to an increase in blood clotting, which raises the risk of a deep vein thrombosis even in healthy people.

Illness Link

“We believe that these falling oxygen levels, together with factors such as dehydration, immobility and low humidity, could contribute to illness during and after flights,” she said.

“This has become a greater problem in recent years as modern aeroplanes are able to cruise at much higher altitudes.”

Dr Humphreys said oxygen deficiency can result in impaired mental performance and shortness of breath.

It can also worsen conditions such as angina and breathing problems.

Experts believe that a significant number of passengers travel with medical conditions that could put them at risk.

Farrol Kahn, of the Aviation Health Institute, a medical research charity promoting better health for passengers, said surveys show that around 10 per cent of travellers are unfit to fly.

“Oxygen reduction particularly affects people with pre-existing conditions, the old and very young, as infants can get into difficulty if they have insufficiently developed lungs,” he said.

“Economies play a role because if the altitude pressure is routinely changed on existing aircraft it cuts their working life.

“But passengers can ask for extra oxygen to be supplied to a section of the cabin and cylinders are available for giving individuals supplementary oxygen.”

Mr Kahn said travellers with cardiovascular disease or respiratory diseases such as bronchitis and asthma should have preflight checks, along with the over-50s, to ensure they were fit to fly.

“The conditions on board, especially long-haul flights, put special stress on essential organs such as heart and brain,” he added.

“At the Institute we provide medical advice to GPs who are concerned about whether a patient can fly after a stroke, for example.”

Mr Kahn said ventilation was cut on some flights to save fuel and, by making passengers sleepy, cut down on extra services needed on board.

A report on the risks of flying from the House of Lords select committee on science and technology said there should be display cards at every ticket sale point and in every doctor’s surgery asking intending passengers: “Are you fit to fly?

Not long ago, saying goodnight to his mom and dad was nearly impossible for 3-year-old Rhett Lamb. In a case that baffled doctors, Rhett was awake nearly 24 hours a day.

“His body would give out but his mind wouldn’t; he’d still be awake,” said Rhett’s mom, Shannon Lamb. “He’d still be alert. It was extremely scary.”

One of the side effects of Rhett’s lack of sleep was bad behavior.

“He was in a bad mood all the time,” Lamb said. “He couldn’t play, he didn’t interact with other children. His frustration level was so high, and it just kept getting worse and worse and worse. He couldn’t communicate with anyone. It was heartbreaking.”

Rhett’s temper got so bad he would hit his mother, even giving her black eyes.

“He would hit you, he would bite you, he would head butt you and anything else around him, and you didn’t know from one minute to the next what was going to happen,” she said.

Rhett’s dad David Lamb said, “It was like he was losing his mind and there was nothing we could do to help him.”

The Lambs, who live in St. Petersburg, Fla., arranged opposite work shifts so one of them could stay home and take care of Rhett.

“You get to the point where you can’t function anymore and you can’t think straight, and you get up in the morning and you take a shower to go to work and you drive to work and you’re a robot,” Shannon Lamb said. “You are an absolute robot. And then you dread coming home ’cause you know it’s the same thing.”

Finally, a Diagnosis
After dozens of doctors’ visits and years of conflicting opinions, Rhett was finally diagnosed with a rare brain condition called chiari malformation.

Chiari malformation is a neurological disorder in which the bottom part of the brain, the cerebellum, descends out of the skull and crowds the spinal cord, putting pressure on both the brain and spine, causing a number of symptoms, including sleeplessness.
Once diagnosed, doctors were able to perform a risky surgery that offered a 50-50 chance Rhett would be able to sleep normally for the first time

Rhett Up to Speed
Dr. Gerald Tuite, a pediatric neurosurgeon at All Children’s Hospital in St. Petersberg, made an incision from the base of Rhett’s skull to the top of his neck to remove bone around the brain stem and around the spinal cord, producing more space and reducing the pressure.

The surgery was a success. Rhett was finally able to sleep through the night, and his behavior improved dramatically.