International Standards and Conformity Assessment for all electrical, electronic and related technologies

March 2011

 

Technology – a life-saving difference

Safely from hip to kidneys all in a day

by Philippa Martin-King

A close friend went into hospital for arthroplasty – in layman's terms, a hip replacement. Although not yet 50, a degenerative condition had forced her to take early action and undergo what, a few years ago was considered major surgery. Today's technology makes the procedure almost banal. New minimally invasive surgery leads to shorter recovery time. After five days you can be released from hospital, already mobile, and, if not running marathons, at least bearing weight and walking without a cane. Of course, there may be complications, in which case sophisticated medical devices provide diagnostic information to help take quick decisions and alleviate the situation.

 

During her operation, it became quickly apparent that she was allergic to some of the pain killers and anaesthetics being administered to her. Her body went into anaphylactic shock. Monitoring systems showed her blood pressure shooting down to 60 over 34 and her kidneys ceasing to function. The hospital had to take emergency action. She was revived by the crash cart team and her circulation re-established. Then she had to undergo dialysis to rid her body of the excess fluids and azotemia, toxins that had built up while her kidneys were no longer able to carry out their normal role.

Technology – making a life-saving difference

My friend's operation points to several areas where technology has made tremendous bounds. New, now often portable medical devices, almost certainly saved her from what could have been a tragic outcome.

Jumping back to life

Until the early 1950s it was only possible to defibrillate the heart through an open chest cavity using AC (alternating current) transformed up to 300 and 1 000 volts through bulky chest-like units and transmitted through paddle electrodes.

I have always enjoyed being involved in the development of medical device safety standards. It has exposed me to an amazing diversity of cutting-edge technologies and allowed me to make many close friends from around the world. Every once in a while I learn that one of the pieces of equipment for which our Subcommittee writes standards has been used on a friend or relative and it is in those moments that I feel a tremendous sense of pride in being involved in this work and in the wonderful and talented people that actually do the work

Mike W. Schmidt,
Secretary IEC SC 62D

It wasn't until the late 1980s that the first portable defibrillators became widespread and people could be shocked back to life with easy-to-use external forces. Now, portable AED (automated external defibrillators) are springing up in all sorts of public places and can be operated by laypersons who need very little specialist training in order to save a life.

 

In December 2010, IEC SC (Subcommittee) 62D: Electromedical equipment, published IEC 60601-2-4, Medical electrical equipment - Part 2-4: Particular requirements for the basic safety and essential performance of cardiac defibrillators.

 

60601-2-4 is part of the authoritative 60601 series on medical electrical equipment. Consulting the projects/publications tab on the SC’s dashboard gives an immediate idea of the work programme and the vast number of standards in preparation. [See the instore article in the March 2010 e-tech for advice on how to access TC dashboard pages directly].

Dialysis – filtering and cleansing

There are two types of dialysis. Haemodialysis is the treatment used particularly for those people who have reached the stage in their life where their kidneys have ceased to function definitively and who will therefore be reliant for the remainder of their life on machinery for survival. Haemodialysis extracts and filters the blood, little by little, before returning it cleaned to the body. It requires incredibly elaborate analysis and sophisticated machinery in order to establish the correct balance of chemicals in the blood and retain the proper levels of hormones, potassium and sodium in the body. It's a lengthy process that requires up to three visits a week, each of which takes several hours. In the past, it involved machinery that could only be operated in the strict confines of a large hospital. Now, newer dialysis machines are providing alternative home treatment, which adds a bit more flexibility to a constraining life schedule.

 

IEC 60601-2-16, Medical electrical equipment - Part 2-16: Particular requirements for basic safety and essential performance of haemodialysis, haemodiafiltration and haemofiltration equipment, covers all the specific medical electrical equipment used in haemodialysis for treating patients suffering from kidney failure.

The people involved in IEC/SC 62D have always been an amazing group. Typically they have significant abilities as engineers and an amazing grasp of the clinical issues associated with the equipment for which we write standards. In recent years, SC 62D has been fortunate in that we have been able to expand that expertise through joint projects with experts from ISO and ASTM Committees as well as other standards development organizations. It is an honour to be able to work with such talented and dedicated individuals who spend countless hours doing this work on a voluntary basis – that's in addition to their “real" day-to-day jobs – motivated primarily by the knowledge they are each contributing to the well-being of those who are in need of medical treatment.

Mike W. Schmidt,
Secretary IEC SC 62D

 

Peritoneal dialysis, also the area of work of IEC SC 62D, uses a catheter, a tube which is placed in the abdominal cavity to flush out the waste products and excess water from the body. The main standard, IEC 60601-2-39, Medical electrical equipment – Part 2-39: particular requirements for basic safety and essential performance of peritoneal dialysis equipment, points to the basic safety and essential performance of peritoneal dialysis medical electrical equipment. Moreover, the publication applies to peritoneal dialysis equipment intended for use by trained medical staff as well as patients, regardless of whether the equipment is used in a hospital or domestic environment. IEC 60601-2-39 covers topics that include protection against electrical hazards from the equipment itself, mechanical, temperature and radiation hazards, measures of EMC (electromagnetic compatibility), the accuracy of controls and instruments and protection against hazardous output situations and other conditions of fault.

Bright red and dark red – the oximeter

During the operation, a pulse oximeter measured the oxygen saturation in her blood and monitored her heart rate. An oximeter is a photoelectric device specially designed for the purpose. It works by passing a beam of red and infrared light through a pulsating capillary bed. The ratio transmitted of red to infrared blood light gives a measure of the oxygen saturation of the blood. An oximeter works on the basis of comparison. Oxygenated blood is a brighter red than deoxygenated blood, which is darkish blue-red. First, the oximeter measures the sum of the intensity of both shades of red and thus the fractions of blood with and without oxygen. On the basis of the pulse – or absence of pulse – the oximeter is able to subtract the intensity of the colour detected when the pulse is absent so that the remaining intensity of colour represents only the oxygenated red blood. The oximeter then displays this on the electronic screen as a percentage of oxygen saturation in the blood. Oximeters are now widespread in intensive care units and hospitals, as well as ambulances and other mobile health care units.

 

Recently, the IEC published yet another part of the 60601 series, IEC 60601-2-23, Particular requirements for the basic safety and essential performance of transcutaneous partial pressure monitoring equipment. Now into its third edition and also the work of SC 62D, IEC 60601-2-23 applies to transcutaneous monitors that are placed on the skin, those devices used with adults, children and newborns, including those for foetal monitoring during birth.

How fast does your heart beat? – the electrocardiogram

Another vital piece of equipment used both in hospitals and outside in rescue situations, such as ambulances and air transport, is the ECG (electrocardiogram). The ECG records heart activity and can measure whether the heart has suffered damage and is beating normally. It can also see the effect of devices such as a heart pacemaker, detect cases of obstructive sleep apnea where breathing has stopped for a period of time or, as in the case of the hip operation, register a heart that has been stressed because of an intense allergic reaction.

 

IEC 60601-2-27 Medical electrical equipment - Part 2-27: Particular requirements for the safety, including essential performance, of electrocardiographic monitoring equipment, specifies the particular safety requirements of ECGs, including essential performance and accuracy of operating data, the interruption of power supply and protection against a variety of hazards.

 

  • A dialyzer is a huge complex machine as big as a dishwasher and full of cleaning fibres to purify the blood.
  • defribillatorSpecialist equipment in an Austrian ambulance in Graz: two-paddle defibrillator with tube of electrode gel above an ECG (electrocardiogram) and pulse oximetry monitor which can operate an external pacemaker and carry out invasive blood pressure measurement.
  • A CPAP (continuous positive airway pressure) system developed to help people suffering from sleep apnea breath normally during the night. Although present in hospitals, it can be used equally well by people at home.

 

 

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