Medical gases fulfil a wide variety of roles within the healthcare industry. Given exclusive access behind the scenes, Rob Cockerill spent a day in a public hospital to see where exactly these gases are at greatest effect.
While the rest of the country is a scene of rush hour hustle, bustle and traffic chaos, the mood is distinctly different in a hospital ward in the South West of England.
The theatre is quiet and peaceful as the patient is prepared and the instruments are readied for the approaching surgery, while the medical staff discuss the operation ahead and brief themselves once more. It’s around 9am and in the ENT department at the Royal Cornwall Hospital Treliske (RCHT), and today’s
team are about to perform a delicate operation that will change the patient’s confidence forever.
The patient, about to receive eye surgery to correct a problematic squint, has been anaesthetised by a syringe of Propofol -or ‘Penguin Milk’ as the team affectionately refer to it. Now soundly under and hooked-up to a raft of tubes and cables, the patient is kept under sedation by a mild and steady infusion of sevoflurane, with the inspired and expired levels constantly monitored.
It’s the first scheduled operation of the day for this ENT team and one of hundreds and thousands performed with each passing month and year. The atmosphere is relaxed and all is running both smoothly and efficiently as the surgery gets underway. Central to this is the dependence on medical gases and the effective function these serve within the realm of the
theatre and wider hospital.
With 27 years experience in the field, Consultant Anaesthetist Mary Daniels leads the anaesthesia team and sits in on the operation throughout. Daniels enthuses about the role of medical gases as she explains, “The gases are a completely integral part of our work. When I first started 27 years ago most of the tubes were run on cylinders and one of the ODA’s main jobs, the ODA being the Operating Department Assistant, was to make sure that the cylinder’s were changed regularly, because you can imagine that they’re not very big cylinders and they last a reasonable time - but you’re working all day and you can soon get through the cylinders.”
As we sit calmly and observe the operation in
progress, Daniels takes the opportunity to introduce the latest trends in rotameter device technology.
These machines both supply and monitor the flow
of oxygen, CO2, sevoflurane anaesthetic and, in
some instances nitrous oxide, that is delivered to the patient. The levels of gases inspired and expired by the patient are displayed with immense precision and the modern machines offer a completely automated
option for maximum efficiency. This is all a far cry from the units of old, as Daniels points out the changes and explains, “This is the old fashioned one, so you dial in what gas flow you want, oxygen and air, we tend to give a 50% mixture. Nitrous oxide used to be used
for all anaesthetics because it’s very good for pain relief. So if you use nitrous oxide, because it’s also a slight anaesthetic and a good pain killer, you can use less of sevoflurane but the trouble with nitrous oxide
is that it does tend to make you feel a bit sick. I don’t use it anymore at all. I just don’t use it, because this (sevoflurane) is such a good agent and with measuring everything it’s just so much easier now.”
“And again, when I first started we didn’t have air on the machines, we only had oxygen. We had oxygen, nitrous oxide and carbon dioxide as well, but that was considered dangerous. Of course we now measure the carbon dioxide with all this fantastic monitoring, but we didn’t used to be able to measure it, so that’s why they took it off the machines - because it was dangerous.”
While keeping a cautious eye on the gas flow levels delivered to the patient as she lay sedated, Daniels notes, “It’s terribly clever this machine. And on the back, here’s your gases coming into the machine, so again, oxygen, air, nitrous, scavenging (going back
out) and 2 cylinders - in case there’s pipeline failure. But that’s incredibly rare.”
Prevalence of medical gases
For the team at Treliske it can be a gruelling day of operation after operation. Today this team are focusing on eye surgery and in particular this morning, procedures to correct squints. It’s all about the muscles in and around the eye – as one muscle pulls harder than it should, the eye goes over to one side
and causes a squint. The surgical team are working hard to remedy this, but the types and specifics of operations vary, as does the time taken to perform them.
“It depends on the length of the operation,
occasionally you’ll have an operation that goes on all day, and other times you’ll do up to 15 because they’re fairly short ones,” Daniels explains.
“It depends, I do different procedures each day. I do Urology, ENT (ear, nose & throat), eyes and I do Obstetrics. We do lots of stuff, we do lots here. We don’t do any plastic surgery, we don’t do any cardiac surgery, we don’t do neurology or brain surgery, but we
do pretty much everything else.”
Throughout the variety of procedures though,
medical gases are prevalent and anaesthesia is
essential. Propofol, a short-acting intravenous
anaesthetic agent, is used to initially ‘knock-out’ the patient and as I see the start of the second operation of the day, I witness this milky-looking fluid delivered through syringe with almost immediate effect. Propofol
could be used throughout the entire operation in theatre, with a steady infusion released, and Daniels is clearly a big fan of this agent.
“Absolutely fantastic and it’s completely changed anaesthesia in a way. It’s a much smoother anaesthetic than what we had before and the patients wake up much better.”
This is generally an expensive method however,
and the more powerful agent sevoflurane is used to keep the patient sedated in theatre. Nitrous oxide is often used as a carrier gas in a 2:1 ratio with oxygen for these powerful agents, while the endeavor for rapid onset and offset leads to using sevoflurane and other
alternative options as the agent of choice.
“They’re both very effective, they’re fabulous.
Compared to the stuff we used to use they’re
fantastic,” said Daniels, adding, “We’re always looking for rapid onset and offset. Nitrous oxide has this and that’s why in maternity you’ll see it used in Entonox,
which is 50/50 obviously. That’s why you use it in labour - and it’s good for the babies because they’re actually getting 50% oxygen as opposed to 21% from the air. It works really quickly, if you take it on a first contraction it will work - but it does make you feel a bit
Indeed, Entonox seems to be very much the gas
of choice in the Princess Alexandra Maternity Wing at Treliske. Having exited theatre and left my trendy scrubs behind, it’s off next to the maternity wing and a chat with Consultant Dr Bill Harvey.
Maternity and Entonox
The Royal Cornwall Hospital at Treliske boasts nine birthing rooms, two birthing pool facilities (located at nearby St Austell and Helston) and a main theatre for caesarean section operations, trial births and capable
of dealing with any other complications that may arise. A back-up theatre facility is also available and a reliable, continuous supply of gases from Linde’s BOC is always available.
Entonox is the gas of choice throughout this
wing, as Harvey points out, “In a delivery suite like this, we use a 50/50 mixture of nitrous oxide and oxygen, which is the Entonox inhaled on demand by women in labour, to control the pain of contraction. In anaesthetics, it’s slightly stronger concentrations of nitrous oxide with oxygen as the carrier gas for our anaesthetic vapours. Less so than we used to, because with the modern anaesthetic vapours there isn’t really the need for the nitrous oxide anymore.”
I take a wander around one of the vacant birthing rooms and see the facilities available to prospective mothers, with the piped-in Entonox readily at hand through a long, black tube above the mother’s bed.
“They’re all introduced to it,” Harvey explains, “it’s always there as an option, a lot of mothers do without any pain relief at all, the advantage of Entonox is that you breathe it in and it works, you breathe it out and very quickly it’s gone - so it is actually quite useful for contractions which come every 4 or 5 minutes and are intense in pain, but then you’ve got no pain in between.”
I ask if there are any alternatives to this seemingly priceless gases mixture and while it appears that a range of options are open to those ladies enduring childbirth, it’s clear that Entonox is widely perceived as the gas of choice.
“If you were using something like morphine and
you gave them enough morphine to douse the top
of the contraction, they’d be unconscious between contractions. So no morphine-like drug or pethodine will ever really cope with the pain of contraction, because it’s not designed for rapid onset and rapid offset - and Entonox is the best thing that we’ve got that does that,” said the consultant.
He went on to say, “There is a modern version of morphine which is nearly as good, which can be given by injection with each contraction, but Entonox is still the best stuff for this particular sort of pain relief.”
So effective and versatile is Entonox, that it is found in use across most walks of hospital life. Harvey describes just some of these applications across the healthcare sector as he says, “It’s also used by paramedics when they’re extracting injured people from cars, giving a substantial amount of pain relief
while their broken ribs are being moved around to get free of the car. It’s used when people are having painful dressings changed on the wards, so children and adults can breathe Entonox and get pain relief.”
“It’s stable at a very wide range of temperatures, so it’s quite useful under most circumstances. It’s just not so good in very cold temperatures, because it starts to
separate and doesn’t vapourise nicely in the cylinder. But you need to get quite substantially below zero to start worrying.”
Helium in the hospital
Later in the afternoon I’m invited to the basement, where Treliske houses its ultra-cool MRI department and uses large quantities of potentially explosive helium.
As a very inert gas and with a uniquely low boiling point, liquid helium is used to cool the superconducting magnets which are used in Magnetic Resonance Imaging (MRI) scanners and research apparatus.
MRI scanners are often fundamental to the functioning of hospitals, diagnosing diseases and detecting problems. It also tends to be the preferred method of scanning for patients due to its lack of radiation and dangerous properties.
Trevelyan Foy, Medical Physicist at the Department of Medical Physics at Treliske, comments, “It’s a lovely imaging modality because we don’t have the radiation dose implications, so you could give someone a CT
scan but you’re committing a dose and there’s a
certain health/cancer risk associated with that.”
“The different modality’s show you different things. I mean CT tends to show you structure, so bones is the classic example. If you’re looking at nuclear medicine, it shows you the function so, for example, you can identify tumour sites or growth sites on bone. Whereas with MRI, it complements this because it shows you the structures in soft tissues so it’s looking at proton density, hydrogen density, so it gives you that information that you don’t get from CT. Without a big price attached in terms of radiation dose. So you can
have one MRI after another, as many as you need.”
In terms of the gases supply into the hospital, the MRI department consumes an enormous quantity of helium and makes economic use of its resources as it operates on an 8am -8pm basis.
Much has been made of the global helium situation in recent months, with tightening supply and global shortages a concern for many in the industrial gases industry. It seems this concern is gradually beginning to filter down into the untouchable healthcare sector too, as Foy notes the first signs of this issue taking effect, “Effectively, the machines are always on, hence from a gases point of view, keeping that continual topping up. You might know that the world price of
helium has gone through the roof, you’re probably much more aware of that. It has got to the stage now where we’re asking for top-ups rather than the manufacturers offering us a top-up. So, source and supply, probably an issue there.”
For all the merits and benefits of helium in the hospital, as I’m ushered around the department and shown the colossal MRI machine sitting majestically in its lair, I’m also informed of the potential dangers of housing such hazardous helium.
Foy explains, “The whole purpose of the liquid
helium cooling is to bring the wires down near to absolute zero, so you can have it superconducting. Should it de-stabilise, the incident that happens is what we call a ‘quench’. Basically because of the resistance, it starts to heat up the helium, some of the helium boils off, the cooling becomes less efficient so the temperature rises and you get positive feedback. So you’ve got a very, very rapid boil-off of the helium
and that means there’s a very sudden increase in the volume of gas.”
“Should that happen, there’s a pipe that feeds out that basically blows the gas outside.”
As I walk away from Treliske at the end of an
insightful and extraordinary day, I leave in confidence that both industrial and medical gases have an essential, if not vital, role to play in the daily workings of a busy hospital.
gasworld was privileged to spend a day behind the scenes at the Royal Cornwall Hospital Treliske in Truro, Cornwall United Kingdom, on 12th March 2008 and would like to sincerely thank all those involved,
for their time, assistance and kind efforts.