Green tube med?

[akroeze]

I was flipping through the channels the other day and I happened to see some medics working on someone. It turned out that it was survivor *shudder* and from the accent I would say they were in Australia or somewhere in that area. What interested me was they were having him breathe through a green tube and it appeared to be for the purpose of pain control (the person had suffered burns). Does anyone know what this is? I've never seen it before.

[Lithium]

Most likely it was Entonox (Nitrous Oxide). It's quite common for pain relief, and even certain provinces (BC and AB that I know of) use it on their ambulances.

I'll still stick to the standard of morphine and fentanyl tho thanks!

[vs-eh?]

Lol...

I was flipping channels yesterday and saw the same show and thought the same thing. I agree with Lithium, someone asked me what it was and I said probably Entonox as well...

I didn't find a picture, basically looked like a green kazoo type thing. Probably the length of the tip of your ring finger to the tip of your thumb in an outstretched hand.

[akroeze]

That was my thought too but for some reason I thought it was a compressed gas in a cylinder?

[aussiephil]

If it was from Australia, then you were seeing Methoxyflurane, or Penthrox.

It is a CNS depressant & works well, acts quickly & washes out quickly. It is also used as an anesthetic agent, with the risk to the patient of renal damae in extended uses. The dru is nephrotoxic & the pt is limited to a max of 6ml/day 15ml/week. Officers on the cars administerin are also limited in my service, to givin a max of 6ml/day as well.

Any other questions, let me know

Phil

[Lithium]

Well Entonox does come in a compressed gas cylinder. It needs to be mixed with oxygen, otherwise ... well if you give it to them straight, they're not receiving any O2.

[Timmy]

During a recent episode of CBS' TV show "Survivor," show participant Michael Skupin, a publisher from Michigan, passed out while starting a camp fire. When he regained consciousness, but still in a partial stupor, he accidentally placed both of his hands into hot coals resulting in severe second degree burns to both of his hands. Stricken with immediate pain, he jumped into a lake to stop the burning. The show's standby paramedics rushed to his side and administered a "Penthrox Inhaler" to ease his pain. While the Penthrox Inhaler is well known to emergency medical caregivers in Australia, those of us watching the show in the U.S. wondered what the green whistle-like device was!

The "Penthrox Inhaler" is a device that administers methoxyflurane (Penthrane or abbreviated MOF) vapors. MOF is a colorless, liquid with a fruity odor with analgesic properties when administered in low doses. After the "Survivor" show EMSvillage.com staff was inundated with questions about this mystery drug. So we decided to get the scoop on pain control "down under." First, let's take a look at the Australian attitude towards pain relief and identify drug options available for prehospital pain control. Then we'll explore the facts about methoxyflurane, the Penthrox Inhaler device, and the effectiveness and safety of MOF as a prehospital pain control medication.

Options for Prehospital Pain Control in the Land "Down Under"

After corresponding with an Australian first responder, a ER nurse, a physician medical director and a paramedic, we were pleasantly surprised to learn that the Australian emergency medical / prehospital care systems accepted standard of care for emergencies includes a humane and aggressive approach to the relief of pain. In fact, Australia is way ahead of the U.S. in their philosophy about prehospital pain control. Among the agents available to "ambos" (a term used to describe EMS workers), on standing orders, are the Penthrox Inhaler, Entonox and intravenous morphine. Even basic level providers in most systems can use the Penthrox Inhaler to help suffering patients.

Jenny Moncur, a student MICA Paramedic from Victoria, Australia said, "As an Australian paramedic, I have used Penthrane on many occasions for control of a patient's pain, and generally with very good, although short term effect. On the occasions that it is not effective, it has generally been because the patient found the smell/taste nauseating and could not use it effectively."

"It is very rewarding to be able to offer pain relief to my patients prior to arrival at the hospital. I believe Australia is unique in this regard, whereby ambos can give analgesia without the need to consult with a physician first. In fact, we have the privilege of being able to operate autonomously, utilizing Clinical Practice Guidelines, although consultation with senior clinicians and medical staff is always available, and is often utilized." said Moncur.

While many providers are pleased with having readily available options to alleviate their patient's pain in both rural and urban systems, some physicians would like to see better medications used like morphine sulfate that have more reliable and more predictable effectiveness. There is also a clear concern about leaking vapors and the health effects on caregivers who inhale them.

Inhaled analgesia may have a role in outdoor areas, but it appears to have limitations in unventilated and enclosed areas. Dr. John L. Holmes, Director Emergency Medicine of Mater Misericordiae Hospitals in Brisbane, Australia said, "Methoxyflurane - what an anachronism! Patients come into the ED sucking on these things like lollipops, the place takes on a fruity odor and god knows how many other people are being exposed to low levels of the stuff. Given its high lipid solubility and slow clearance, it could be interesting to measure psychomotor performance of ambulance officers and other clinical personnel working with these patients and breathing in MOF over time."

Is MOF clinically effective?

Is MOF an effective analgesic? The answer is, 'yes' according to the manufacturer's literature and 'maybe and sometimes' according to field reports! Field EMS workers report that only some patients obtain sufficient relief with MOF. Some patients who do not benefit from MOF will obtain relief with Entonox and vice versa. There is very little literature available that predicts a reliable percentage of patients who will obtain pain relief with this drug. In fact, one pediatric study indicated that 91.6% of those treated with MOF required additional analgesia in the Emergency Department. One reason that may explain inadequate effectiveness in some patients is that the drug is inhaled and self-administered leading to inadequate dosage in some patients who use the device incorrectly or can't self administer it properly. That may also partially explain some of the results of the pediatric study.

According to Dr. Holmes, "Patients inhaling MOF still seem to be in pain unless they're off the planet with it. Similarly I think it is over rated in the prehospital situation. I also have concerns about obtunding LOC with these agents especially with full stomachs, head injuries and the rest. It's gratifying to see the Victorian Ambulance Service freeing up the use of morphine. The intravenous titration of morphine remains the gold standard for acute pain relief."

Controversial Issues

What are the main controversies surrounding the patient care guidelines for pain control? They include the use of MOF vs. Entonox, inhaled analgesia vs. intravenous morphine, and potential for abuse of MOF.

MOF vs Entonox(nitrous oxide)

In Australia methoxyflurane has largely replaced Entonox (nitrous oxide) as the inhaled analgesic of choice. Although many services still carry both, according to reports from several physicians and EMS workers, this switch is largely because the Penthrox Inhaler is easily stored, portable and lightweight. This is in contrast to Entonox which requires the rescuer to carry both an oxygen tank and a nitrous tank.

One Australian first-response level EMS worker associated with the Australian Department of Defense said, "Comparing Entonox and methoxyflurane, I have found that methoxyflurane is the better of the two. The main reasons for this are the cost and portability of the equipment required. In my workplace Penthrox is the front-line analgesic given until an ALS trained person arrives. Only then with the higher level of training and expertise will a more effective analgesia be given."

Inhaled Analgesia vs. Intravenous morphine

When the inhaled analgesia works it has a quick onset and short-term effect. This means that patients who may be ill or injured in a rural area where ALS is not readily available can at least benefit from some pain control until ALS arrives with better medications, like intravenous morphine. Several physicians and nurses reported concerns about contamination of the ambulance and that there are concerns for the EMS worker's health due to exposure of the methoxyflurane vapors. While there are some engineering controls, leakage can and does happen with any inhalation system. Many report that these reasons should prompt a movement away from inhaled analgesia, at least in enclosed spaces.

Australia is also beginning to take a look at how practical using inhaled analgesics are with the increased availability and capability of administering intravenous morphine, the accepted 'gold standard' for the treatment of acute pain. Moncur says that she is now training as an MICA (intensive care) paramedic and will have morphine sulfate at her disposal. "I still find occasions to use Penthrane, usually while I am gaining IV access, if the patient is in real distress, just to give some quick relief until the good stuff kicks in. There is a role for Penthrane, but MS is obviously preferable."

Other comments included that Australia's EMS system is changing to more use of IV Morphine, but in rural areas, at special medical events, or in situations where there are long ALS response times, that the use of the Penthrox Inhaler may, and should continue for intermediary treatment of pain. Some also say after inhaled analgesia has been provided that IV pain medication is often effective at decreased dosages.

Abuse Potential of Methoxyflurane

Concerns about abuse are very real with any controlled substance. We asked if there are any actual or potential abuse issues with MOF. MOF and Entonox are controlled substances and must be accounted for in a drug register. Unfortunately, in the past, there has been some abuse by providers. Stricter controls on storage and accounting for the drugs have made it much more difficult to obtain them. Moncur said, "By virtue of the fact that Australian paramedics can administer analgesia without consultation, there will always exist the possibility of exploitation of the system by some."

An interesting side effect of MOF includes anecdotal reports on its effect on the human libido, especially in women. Moncur said, "One very well recognized side effect, at least recognized by providers, I have not seen it in print, is the effect of lowered inhibitions in users, and most particularly in females. Most male ambos in Australia who have given Penthrane have been propositioned by female patients of any age. Obviously, care, compassion and tact is required by those of us who administer this drug."

The Drug: Methoxyflurane

Methoxyflurane (Penthrane, MOF) is a fluorinated hydrocarbon and volatile liquid intended for vaporization and inhalation of low doses for analgesic effects. The drug is administered through the Penthrox Inhaler device.

Introduced in the 1960s, the drug initially showed promise because it appeared to be a safer anesthetic compared to halothane since it had less proarrhythmic effects and also appeared to provide more muscle relaxation than did halothane. It was discovered that an interesting property of methoxyflurane is that at subanesthetic (low) concentrations it induces analgesia (not anesthesia). Methoxyflurane is extremely soluble in blood and tissues resulting in slow induction and prolonged recovery. In addition, it undergoes extensive hepatic metabolism resulting in plasma fluoride concentrations sufficient to induce severe nephrotoxicity in some human patients. As a result, methoxyflurane lost its place in human medicine as an anesthetic but, it is still used as an inhaled analgesic by emergency medics in Australia. At low doses the nephrotoxic effects have been reported to be low risk.

The Penthrox Inhaler is manufactured by a firm called Medical Developments located in Australia. The inhaler is self-administered by the patient and is indicated for emergency pain relief. The inhaler can be used with oxygen or with ambient air. Based on the available research, it is not approved for human use in the US, although it is used in veterinary medicine.

Clinical Use of Methoxyflurane

Note: The following information is based on analgesic levels of administration. The use of Methoxyflurane in higher doses as a sole anesthetic agent is not recommended.

Methoxyflurane comes packed in 3 ml sealed bottles. The concentration of vapor when inhaled through the Penthrox Inhaler is about 0.2% to 0.4% with the diluter hole uncovered and about 0.4% to 0.7% with the diluter hole covered. Pain relief commences after 8-10 breaths, and continues for several minutes after use: an advantage when extricating trapped victims. According to the manufacturer, Medical Developments, the Penthrox Inhaler is widely used throughout Australia in Ambulance Services, First Aid Stations, Ski Rescue Services, Mines, Palliative Care, Obstetrics & Burns Units, Defense Forces.

Indications:

General indications for the use of methoxyflurane include:

Prehospital pain relief with or without the simultaneous administration of oxygen.

Management of pain in trapped or inaccessible patients.

Short surgical procedures such as the change of burns dressings.

Palliative care.

Contraindications:

Patients with preexisting renal disease, impairment of renal function, toxemia of pregnancy, or concurrently using tetracyclines should not receive methoxyflurane unless the benefits outweigh the increased risk of nephrotoxic effect.

Nephrotoxicity can result from high dose methoxyflurane administration following anesthesia. In order to minimize renal injury the recommended maximum dose for methoxyflurane analgesia is 6 ml per day or 15 ml per patient. What is unknown, however, is how nephrotoxic the drug is when administered to patient's who are hypoperfused (in shock). Since the hypoperfused patient's kidneys are already vulnerable to injury from hypoxia it is really not known what dosage of MOF is safe in this patient population.

Administration:

Methoxyflurane analgesia is self administered under supervision using the hand held Penthrox Inhaler. If required, oxygen can be introduced simultaneously through the nipple in the base cap. The Penthrox Inhaler is charged with 3 ml or 6 ml of methoxyflurane, which provides approximately 25 or 55 minutes of analgesia respectively. The lowest effective concentration of methoxyflurane to provide analgesia should be used. With the diluter hole uncovered the inhaled vapor concentration is about 0.2 0.4%. Covering the diluter hole with a finger increases the inhaled concentration to about 0.4 - 0.7%. The maximum dosage allowed per day is 6 ml, or 55 minutes. See the chart at the right for more information about administration.

Side Effects/Precautions:

Methoxyflurane provides analgesia at low concentrations, therefore, drowsiness may occur but consciousness is retained. The patient may become nauseated or intolerant of the odor. This may result in subtherapeutic doses and inadequate pain relief. Because the drug is self-administered if the patient becomes unconscious the inhaler is dropped by the patient avoiding continued administration. One possible advantageous effect that has been observed in practice, is that the dose for the subsequent administration of narcotics may be able to be reduced. Although, the literature does not adequately describe or validate this anecdotal report.

During Methoxyflurane analgesia, cardiac side effects are rare. Some decrease in blood pressure accompanied by bradycardia may also rarely occur.

The Administration Device: The Penthrox Inhaler

The Penthrox Inhaler is handheld inhaler, known commonly as the "whistle," for use with methoxyflurane and air or oxygen for pain relief. The Penthrox Inhaler can also be used for oxygen therapy. It is a green whistle-like tube with a wick. 3ml of

the methoxyflurane solution is poured into the back of the inhaler. The dosage is regulated by two diluter holes that offers two concentrations.

According to the manufacturer, when an oxygen hose line is attached to the inlet nipple in the base cap of the Penthrox Inhaler, 3 LPM provides average inspired oxygen concentrations of 35% and 8 LPM provides in excess of 50%. It is recommended that the line of the oxygen flow be arranged longitudinal as experiments have shown that side or other ports of entry do not achieve adequate inspired oxygen concentrations. Also according to the manufacturer, by using a longer hoseline, the Penthrox Inhaler can be used to provide oxygen enriched air, with or without pain relief, to remotely trapped victims.

Summary

Australia, especially in the rural area known as the "Outback" challenges prehospital care systems with tough environmental conditions and terrain. It is also tough for the patient in acute pain who may be hours from a hospital or ALS level ambulance care. The Penthrox Inhaler and MOF is used in wilderness medicine, mines, rural settings and even in cities where access to hospitals is only minutes away. While its clinical reliability and safety during use in enclosed areas may be in question, there seems to be a clear indication that inhaled analgesia should maintain a role in prehospital care settings such as in the wilderness or in rural settings until ALS level care arrives. However, there is a clear need for reliable prehospital studies to determine the appropriate role that inhaled analgesia should play to improve the pain control treatment that patient's receive in the field. There are more questions than answers. The Victorian Ambulance System is moving towards intravenous morphine use and is recognizing that this is the "gold standard" for control of acute pain.

We must commend the Australian healthcare system for their commitment to providing high-quality prehospital patient care. The Australian philosophy towards alleviating pain in the prehospital setting sets an example of a healthcare attitude we can all learn from. The U.S. medical community is not yet as liberal, or compassionate, with its current attitude toward routine prehospital acute pain management. However, it is also not practical for every EMS system in the U.S. to administer parenteral pain medication. The Penthrox Inhaler and MOF are not approved for use in the United States. While nitrous oxide is approved for use in the U.S., it is not used routinely except in some rural EMS systems it can't be used in unventilated areas. Should we be using more inhaled analgesia in the U.S.? That will depend on whether nitrous oxide mixtures, MOF and the Penthrox Inhaler device can be studied more aggressively to discover if they are consistently effective enough to warrant their continued use.

[aussiephil]

Timmy,

i assume this wasnt your work, who wrote all this?

Penthrox/methoxyflurane is an inhalation anesthetic that has analgesic qualities. It works. I know because i use it. I dont need a volume of crap to tell me as much. I speak from experience.

To say we are advanced of the US is a bold statment & i hope u can back it up. I will ask you again, when making reference to services here, please know your facts. If you are spaking for Vic Ambulance, state that.

ASNSW also use Fentanyl. The primary reason is to allow for extended transports, & reducin the possibilities of nephrotoxicity in both patient & more importantly the administering officer.

Timmy, please learn your stuff, not quote for all of us & read other posts before usin cut & paste in the forums.

Phil

:twisted:

[akflightmedic]

Timmy,

My only request is when you post something like that, please credit the source otherwise it appears as if it is your own.

While Phil disagrees with you posting a "volume of crap", I appreciated it as I was very unfamiliar with the drug and delivery route and it was good for me to read all about it. I now have learned something from you Timmy, even if it was only cut and paste of an article that I have not run across before, you did the hard work for me. Thanks.

Just always be prepared to defend or justify any statements you make as someone in life will always call you out on them eventually.

[DwayneEMTP]

Timmy, please learn your stuff, not quote for all of us & read other posts before usin cut & paste in the forums.

aussiephil, Other than failing to reference his work (which is a HUGE deal Timmy) Why was the cut and paste inappropriate?

Dwayne