Buyers Guide

Know about this Pain-eliminator

Nancy Singh tells you all about the latest anaesthesia machines.

No pain, No gain? Not really, at least in this case. The exclusion of pain—ultimately this is where it all boils down to and it is here that anaesthesia comes to the rescue. It is hard to believe that simple innovations can change the course of surgeries. It is courtesy anaesthesia that all the medical landmarks are possible.

Fundamentals

Basically, anaesthesia machine is just about compressed gas supply from pipeline/cylinders, vapourisers for anaesthetic agents and patient circuits. From a minor procedure, with a shot to numb the area to a more serious surgery in which you are made 'asleep’, anaesthesia becomes the base. Anaesthesia is the use of medication to prevent the feeling of pain or other sensations during surgery or other procedures that might be painful (such as getting stitches or having a wart removed).

The fundamental principle of anaesthesia is to use drugs that block the pain signals that pass along your nerves to your brain. When these drugs wear off, you start to feel normal sensations again, including pain. Some of these medications work on your whole body, while some of the medications work directly on the nerves going to parts of your body.

The American Society of Anesthesiologists (ASA) compares the nervous system to an office's telephone system—with the brain as the switchboard, the nerves as the cables, and the body parts feeling pain as the phones.

Given as an injection or through inhaled gases or vapors, different types of anaesthesia affect the nervous system in various ways by blocking nerve impulses and, therefore, pain. In today's hospitals and surgery centers, highly-trained professionals use a wide variety of safe, modern medications and extremely capable monitoring technologies. An anaesthesiologist is the one who specialises in giving and managing anaesthetics.

Types of Anaesthesia

Anaesthesia is broken down into three main categories: general, regional, and local, all of which can be administered using various methods and different medications that affect the nervous system in some way.

General Anaesthesia: The goal is to make and keep the person completely unconscious (or 'asleep') during the operation, with no sensations, feeling of pain, awareness, movement, or memory of the surgery. General anaesthesia can be given through an IV (which requires a needle stick into a vein, usually in the arm) or by inhaling gases or vapors.

Regional Anaesthesia: An anaesthetic drug is injected near a cluster of nerves, numbing a larger area of the body (such as below the waist). A person who receives regional anaesthesia is usually asleep after the procedure is done. However, in children and those who do not like needles, can be made asleep before getting regional anaesthesia as main form. In older people or those who would be at unacceptable risk by being asleep may be awake or sedated during the procedure. For example, if a person is overweight, it may be difficult for the anaesthesiologist to feel the bones that help guide correct placement of the needle. To avoid nerve damage, getting feedback from an awake person would be a safer option. This type of anaesthesia includes things like epidurals, caudal blocks (which are similar to epidurals, but are placed in the tailbone), and spinal blocks (which further numb the lower body) and nerve blocks.

Local Anaesthesia: An anaesthetic drug numbs only a small, specific part of the body (for example, a hand or patch of skin). Depending on the size of the area, local anaesthesia can be given as a shot, spray, or ointment. With local anaesthesia, a person may be awake or sedated. Local anaesthesia lasts for a short period of time and is often used for minor surgeries and outpatient procedures (when patients come in for an operation and can go home that same day). If you are having surgery in a clinic or doctor's office, (such as the dentist or dermatologist), this is probably the type of anaesthetic that will be used.

The type and amount of anaesthesia will be specifically tailored to your needs and will depend on various factors, including your age and weight, the type and area of the surgery, any allergies you may have, and your current medical condition.

Classification

Anaesthesia machines are of two types: draw over, which is still used in peripheral primary healthcare places and remote outdoor location, and continuous flow anaesthesia machines, which is common in the tertiary care and city hospitals needing a constant source of compressed gas. Continuous-flow anaesthetic machine is designed to provide an accurate and continuous supply of oxygen and nitrous oxide, mixed with an accurate concentration of anaesthetic vapour (such as isoflurane), and administered to the patient at a safe pressure and flow.

Modern machines incorporate a ventilator, suction unit, and patient-monitoring devices. Earlier, anaesthetists often carried all their equipment with them, but the development of heavy and bulky cylinder storage and increasingly elaborate airway equipment meant that this was no longer practical for most circumstances. The anaesthetic machine is usually mounted on wheels for convenient transportation.

TriService Apparatus is a simplified Drawover anaesthesia delivery system invented for the British armed forces, which is light, portable and may be used effectively even when no medical gases are available.

Components

The anaesthesia machine is a tool to assist the vigilant anaesthesiologist in delivering the safest of anaesthetics to the patient. This machine consists of many parts that work together during the administration of a general anaesthetic.

Vital controls for the flow of oxygen, air, nitrous oxide and inhalation agents that are essential to a successful general anaesthetic are included in this machine. A breathing machine (ventilator), oxygen analyser, and scavenger system are also added components. Monitor allows the anaesthesiologist to follow vital signs from the body. These monitors include EKG, blood pressure, oxygen saturation, temperature, and end tidal gas measurements.

Old versus the New

Concept is the same, but enhancement and digitisation is an extension. The original concept was invented by the British anaesthetist HEG Boyle. From 1917 to 2007, technology has moved in leaps and bounds, but even today the application of Boyle's Apparatus has not changed much.

Despite numerous modifications, the modern apparatus retains many of the features of the original Boyle's machine, a British Oxygen Company trade named in honour of the inventor.

Even today, it is the primitive Boyle's apparatus which is used and most preferrable in our country. "Firstly, it is not expensive and it is a fact that most people keep this machine to safeguard against medico-legal implications," informs Satyam Vyas, Modality Manager, Draeger Medical India Pvt Ltd, Mumbai.

Low Maintenance

The major change is less mechanical work. "Today, everything is digitised, so the mechanical work is reduced but Boyle's is as good as today's machine," says Dr Arpana Kaushik, Consultant Anaesthiologist, Wockhardt Hospitals, Mumbai.

Most advanced anaesthetic machines, normally called as workstations, have anaesthesia machine and gas and haemodynamic monitoring all in one, but are costly.

It is precision where latest technology scores as it has in-built safety alarms. "Definitely, the degree of sophistication goes up and it also saves a lot of energy. It can be used with lesser amount of oxygen and even lesser agents, which makes it more environmental-friendly," informs Dr Kaushik.

Trusting the Computer?

Yes, this is the question that lingers on the mind. "I totally depend on the computer. So, if the computer or machine is wrong, I am lost," avers Dr Kaushik. It is then when the results are not co-relating, that anaesthiologists prefer to trust their experience and go the primitive way.

Also, one of the practical problems which adds to the advantage of Boyle's, is that all the systems today operate on electricity. In Boyle's, you have an extra outlet wherein if everything fails that extra oxygen supply is provided through the cylinder, "But the latest models have done away with this extra coat," states Dr Kaushik. Hence, users feel the need to have a stronger battery back-up option in case the electricity fails, which as we know in our country is pretty much the case. Most surgery centers don't have back-up anaesthesia equipment as well, citing cost as a reason.

"All of these new systems have battery back-up and some warn of impending power loss, suggesting a switch to manual ventilation. In the event of a dead battery, all can deliver oxygen, but not measure it electronically. They allow manual or spontaneous ventilation with manual control of the APL valve," informs Dr V Muralidhar, Senior Consultant, Department of Anaesthesiology and Intensive care, Indraprastha Apollo Hospitals, New Delhi.

Market

"Today, systems have battery back-up and some also warn of impending power loss, suggesting a switch to manual ventilation" - Dr V Muralidhar Senior Consultant, Department of Anaesthesiology and Intensive Care Indraprastha Apollo Hospitals New Delhi

The medium to high-end market is held by Draeger, Datex-Ohmeda/GE Schiller. "In India, however, regional players manufacturing the basic apparatus rule the roost," informs Vipul Gogru Director, Critical Care Systems,Meditronics, Mumbai.

Managed healthcare has brought about many changes and as managed care looks for less-expensive ways to perform surgery, the growth of outpatient and same-day surgery in hospitals, free-standing surgical centers (FSSCs) and doctors' offices has exploded. Frost and Sullivan expected the market product revenue for anaesthesia gear and related disposable products to rise to $542 million in 2005.

This trend to outpatient surgery demands new types of anaesthesia. In response, inhaled agents which allow more rapid emergence and shorter recovery periods (like Desflurane and Sevoflurane) have been developed, and there has been wider use of IV anaesthesia with agents like Propofol. Increasingly, two or more agents are used in combination - either two inhaled agents, or a combination of IV and inhaled agents.

The above trends, plus the introduction of two new inhaled anaesthetic agents, have changed the configuration of of anaesthesia workstation, vaporisers to the electronic gas monitors used to track gas concentrations. Coupled with safety issues related to older configurations, these factors resulted in the wholesale replacement of gas machines in the late 1980s and early 1990s, and in electronic gas monitors in the early 1990s.

Outpatient Care Affects Demands

A steady increase in the elderly patient population and the trend toward more outpatient surgeries is raising the demand for various anaesthesia and respiratory products. Greater emphasis on hygiene and infection control as well as the requirement for spontaneous breathing and sophisticated ventilation modes are expanding the market. The surge in emergency medical services and free-standing surgery centers is also expected to prop up market growth.

Rising Competition

The need for high-quality patient care and a free flow of information that improves the response time of clinicians to vital signs and alarms also encourage demand for such advanced products. However, future growth will be restricted due to market saturation and cost containment, according to a Frost and Sullivan study.

Safety Issue

Anaesthesia is safer today than it has ever been before. The risk of death from the anaesthetic today is estimated at 1/200,000 anesthetics. This number in 1982 was 1/10,000. The risk of undergoing anaesthesia can be affected by age, sex, weight, habits (smoking /alcohol / drugs) and other acute or chronic diseases.

Ether is a drug that is not presently used in the practice of anaesthesia. This was a drug that was used about 25 years ago, for the induction and maintenance of the anaesthetised state, but it has since given way to better drugs with fewer side effects. For adults, IV medications like Sodium Pentothol and Propofol are used to put them to sleep. Inhalation agents, Forane and Sevoflurane, are the inhalation drugs presently used in the manner that ether was used in the past.

The safety of anaesthetic procedures has improved manifolds, thanks to advances in technology and the extensive training anaesthesiologists receive.

All Parameters, One Monitor

"Over the years, advanced technology has made use of the machine simple in a few terms, but for technophobics they are just a nightmare" - Dr Vinayak Desurkar Consultant Anesthiologist,Dinanath Mangeshkar Hospital,Pune

Industry leaders acknowledge that the trends favour one monitor for all parameters. Equipment design is moving in the direction of packing as many parameters as possible, onto one monitor. "This is what ideally the future looks like," says Vyas of Draeger. It contains virtually all the equipment including a pulse oximeter, respiratory gas monitor, carbon dioxide monitor, nitrogen agent monitor and the non-invasive blood pressure monitor and ventilator.

The high-end units are equipped to monitor conditions such as cardiac ischemia (called ST segment monitoring). This is vital during operations such as open heart surgery or when the patient has a pre-existing cardiac disease. In most cases, the only parameters required are ECG, blood pressure, pulse oximetry and oxygen analysis. However, the industry is moving toward consolidation of parameters. Space is very limited as they have to meet the need for monitors and the need for more parameters, but the size cannot be increased much.

We can expect changes that facilitate data processing ease and flexibility coming in the form of modular equipment. But cost would be a hurdle. And when sold on computer technology, there would be still unanswered questions like funding to network to other systems.

Dynamic growth is in integrating anaesthesia monitoring equipment with other user-friendly features, such as flexible data management, ease of information retrieval and extending anaesthesiology services from operating rooms into outpatient and ambulatory units. So how much is too much?

Dr Vinayak Desurkar, Consultant Anaesthiologist, Deenanath Mangeshkar Hospital, Pune concludes, "Over the years, technology has advanced excellently and has made use of the machine simple in a few terms, but for technophobics they are just a nightmare."

nancy.singh@expressindia.com