The History of Defibrillation

defibrillation

A defibrillator is a device that sends electrical energy, or shock, to the heart. The aim of using a defibrillator is to treat cardiac arrest. The need for this generally arises when the patient has ventricular fibrillation or ventricular tachycardia, which are life-threatening arrhythmias that occur when contraction of the ventricles become abnormal. Defibrillators have electrocardiogram (ECG) leads and adhesive patches (or paddles). The adhesive electrodes are the patches placed on the patient’s chest that deliver the electric shock.

The History of Defibrillation

In 1899, two physiologists from the University of Geneva, Jean Louis Prevost and Frederic Batelli, discovered that small electric shocks could cause ventricular fibrillation in dogs. Later, in 1933, a device was invented to send an electric shock to the heart as a substitute for administering cardiac medications.

In 1947, the first defibrillation was carried out by Claude Beck who was a professor of surgery at Case Western Reserve University. The defibrillator he used had internal paddles that were placed on each side of the heart.

Before the end of the 1950s, defibrillation was successfully performed only when the chest cavity of the patient was open during the surgery. In this case, the defibrillator had electrodes in the shape of paddles so that flat ends could be placed on either side of the exposed heart.

As the 1950s gradually came to an end, the closed-chest defibrillator device was invented. One of the basic differences between the open and closed-chest devices was that the closed-chest defibrillators required more voltage for operation. It was invented by Dr. V. Eskin and A. Klomov.

Thus far, the defibrillators in existence used alternating current. In 1959, Bernard Lown began to develop new ideas to make the device more energy efficient. Lown’s work led to the discovery of Direct Current (DC). Further development lead to the Biphase Truncated Exponential (BTE) waveform. With the BTE waveform, the defibrillators could use lower energy levels, which reduced the weight of the defibrillators that were later manufactured.

In the 1960s, Professor Frank Pantridge of Belfast began to introduce portable defibrillators for hospitals. This invention is now one of the most important tools that emergency medical services carry to resusitate people that suffer cardiac arrest. Portable units set forth the production of automatic defibrillators—devices with the ability to analyze heart rhythms.

The biphasic waveform did not completely replace the Lown waveform until the end of the 1980s. The waveform allowed defibrillators to work more quickly than the previous types. This in turn reduced the energy level needed for defibrillation. The success rate for treating cardiac arrest also improved.

In 1969, the research for making implantable cardioverter-defibrillator (ICD) began as a result of needing to provide adequate health care for victims of cardiac arrest. In 1980, the first implantable device was used at John Hopkins Hospital by Dr. Levi Watkins. Today, frequent victims of cardiac arrest are given the device for their aid at any time.

Types of Defibrillators

There are different kinds of defibrillators in use today. They include the manual external defibrillator, manual internal defibrillator, automated external defibrillator (AED), implantable cardioverter-defibrillator (ICD), and wearable cardiac defibrillator.

  • Manual external defibrillator: These defibrillators require more experience and training to effectively handle them. Hence, they are only common in hospitals and a few ambulances where capable hands are present. In conjuntion with an ECG, the trained provider determines the cardiac rhythm and then manually determines the voltage and timing of the shock—through external paddles—to the patient’s chest.
  • Manual internal defibrillator: The manual internal defibrillators use internal paddles to send the electric shock directly to the heart. They are used on open chests, so they are only common in the operating room. It was invented after 1959.
  • Automated external defibrillator (AED): These are defibrillators that use computer technology, thereby making it easy to analyze the heart’s rhythm and effectively determine if the rhythm is shockable. They can be found in medical facilities, government offices, airports, hotels, sports stadiums, and schools.
  • Implantable cardioverter-defibrillator: Another name for this is automatic internal cardiac defibrillator (AICD). They constantly monitor the patient’s heart, similar to a pacemaker, and can detect ventricular fibrillation, ventricular tachycardia, supraventricular tachycardia, and atrial fibrillation. When an abnormal rhythm is detected, the device automatically determines the voltage of the shock to restore cardiac function.
  • Wearable cardiac defibrillator: Further research was done on the AICD to bring forth the wearable cardiac defibrillator, which is a portable external defibrillator generally indicated for patients who are not in an immediate need for an AICD. This device is capable of monitoring the patient 24-hours-a-day. It is only functional when it is worn and sends a shock to the heart whenever it is needed. However, it is scarce in the market today.

When Not to Use a Defibrillator

Defibrillation is not indicated if the heart rhythm has completely stopped, as in asystole, or sometimes called “flat line,” or has pulseless electrical activity (PEA). Also, defibrillation is not indicated if the patient is conscious or has a pulse. Inappropriately given electrical shocks can cause dangerous arrhythmias, such as ventricular fibrillation.

Although defibrillators have specific indications and were initially exclusive to trained professionals, it is now possible to have one at home. Modern defibrillators are easy to use and do not require years of experience. In fact, a few tips from a health-care professional and a review of the the manual is all that may be needed to correctly intervene in a cardiac emergency. This development is helpful in reducing the number of death rates caused by sudden cardiac arrest and other heartbeat-related problems each year.

FALLS THROUGH SKYLIGHTS AND PLASTIC ROOF SHEETING

FALLS THROUGH SKYLIGHTS AND PLASTIC ROOF SHEETING

Safety Alert |

This safety alert reminds persons of the risks associated with working on roofs with skylights or plastic roof sheeting, as well as the actions required to ensure those risks are eliminated or minimised.

BACKGROUND

In March 2018, one worker died and two others received serious injuries, including fractures and spinal injuries, after falling through a skylight or plastic roof sheeting.

These incidents demonstrate that it is not just exposed edges that create the risk of a fall when working on roofs.

KEY CONSIDERATIONS

Not all areas on a roof are safe to walk on or step or fall onto if you stumble or lose balance.

Even plastic sheeting that is claimed to be trafficable can become brittle over time and is highly reliant on correct installation to be trafficable.

When on existing roofs, dirt and algal growth can make it harder to notice plastic sheeting, especially if it has the same profile as the surrounding sheeting.

Roof sheeting profiles, surface changes, dirt, moisture and obstructions on roofs make it more likely that a person will stumble and deviate from their intended travel path.

ACTION REQUIRED

Before commencing work on an existing roof, carry out an inspection to determine:

  • the presence and condition of sky lights, plastic roof sheeting and other brittle roof sheeting such as asbestos cement sheeting
  • the presence and integrity of safety mesh.

Whether it’s an existing structure or one under construction, consider skylights and plastic roof sheeting as non-trafficable areas unless certified as trafficable. Even then, ensure that the installation has been checked and proven to comply with trafficable installation instructions. Note: cut down sheets may need additional fixings and even a missing screw can make a sheet non-trafficable.

Where non-trafficable, provide appropriate fall prevention/protection measures and develop work methods to prevent people from stepping or falling onto non-trafficable surfaces.

To ensure the necessary control measures are being applied as the work progresses, an ongoing review of the work should also be carried out.

MEASURES FOR CONTROLLING THE RISK

Control measures to prevent a person from falling through a fragile roof or skylight include, but are not limited to:

  • plan the work to avoid accessing non-trafficable areas
  • work from a solid construction to avoid standing on the roof itself
  • install temporary work platforms (crawling boards) and roof ladders as appropriate
  • install barriers, such as guard rails or covers, that are secured and labelled with warning signs
  • install safety mesh
  • install a fall arrest system (harness) which has adequately-installed anchorage points, along with training and instruction in the use.

FURTHER INFORMATION

Snake Bite

 

Snake Bite

Following teaching a First Aid course yesterday where we had a visit from a juvenile brown snake in the classroom, I thought it timely to remind everyone about Snake Bite treatment.

Australia has some 140 species of land snake, and around 32 species of sea snakes that have been recorded in Australian waters.

There are around 100 Australian snakes that are venomous, although only 12 are likely to inflict a wound that could kill you. These include Taipans, Brown snakes, Tiger snakes, Death Adders, Black snakes, Copperhead snakes, Rough Scaled snakes as well as some sea snakes.

Most snake bites happen when people try to kill or capture them. If you come across a snake, don’t panic. Back away to a safe distance and let it move away. Snakes often want to escape when disturbed.

All snake bites must be treated as potentially life-threatening. If you are bitten by a snake, call triple zero (000) for an ambulance.

Different types of snake bites

Dry Bites

A dry bite is when the snake strikes but no venom is released. Dry bites can be painful and may result in swelling and redness around the area of the bite. This occurs because you don’t look like something the snake wants to eat.

Because you can’t tell if the bite is a dry bite, always assume that you have been injected with venom and manage the bite as a medical emergency. Once medically assessed, there is usually no need for further treatment, such as with antivenoms. Many snake bites in Australia do not result in envenomation, and so they can be managed without antivenom.

Venomous Bites

Venomous bites are when the snake bites and releases venom (poison) into a wound. Snake venom contains poisons which are designed to stun, numb, or kill other animals.

Symptoms of a venomous bite include:

  • severe pain around the bite, this might come on later
  • swelling, bruising or bleeding from the bite
  • bite marks on the skin (these might be obvious puncture wounds or almost invisible small scratches)
  • swollen and tender glands in the armpit or groin of the limb that has been bitten
  • tingling, stinging, burning or abnormal feelings of the skin
  • feeling anxious
  • nausea or vomiting
  • dizziness
  • blurred vision
  • headache
  • breathing difficulties
  • problems swallowing
  • stomach pain
  • irregular heartbeat
  • muscle weakness
  • confusion
  • blood oozing from the site or gums
  • collapse
  • paralysis, coma or death

In Australia, there are around two deaths a year from venomous snake bites.

Snake identification

Identification of venomous snakes can be made from venom present on clothing or the skin using a so called ‘venom detection’ kit. For this reason, do not wash or suck the bite or discard clothing.

DO NOT attempt to kill the snake for purposes of identification, as medical services do not rely on visual identification of the snake species regardless.

Antivenom is available for all venomous Australian snake bites.

First aid for snake bites

For all snake bites, provide emergency care including cardiopulmonary resuscitation (CPR) if needed. Call triple zero (000) for an ambulance. Apply a pressure immobilisation bandage and keep the person calm and as still as possible until medical help arrives.

Avoid washing the bite area because any venom left on the skin can help identify the snake.

DO NOT apply a tourniquet, wash, cut or suck the venom.

Pressure immobilisation bandage

A pressure immobilisation bandage is recommended for anyone bitten by a venomous snake. This involves firmly bandaging the area of the body involved, such as the arm or leg, and keeping the person calm and still until medical help arrives.

Follow these steps to apply a bandage using the Pressure Immobilisation Technique (PIT):

  • Start at the bite itself, wrapping around it three (3) times. It should be tight, and you should be unable to slide a finger between the bandage and the skin. Then continue down the limb till the very tips of the fingers are showing. Continue back up the limb until reaching the armpit or groin. Splint the limb including joints on either side of the bite.
  • Keep the person and the limb completely at rest. Mark the site of the bite with a coin over the bite prior to bandaging or write a cross on the bandage with a pen and the time of envenomation.

Anaphylaxis

Snake bites can be quite painful. Occasionally some people have a severe allergic reaction (anaphylaxis) to being bitten. In this case, the whole body can react within minutes which can lead to anaphylactic shock. Anaphylactic shock is very serious and can be fatal.

Symptoms may include:

  • difficulty talking
  • difficulty swallowing
  • difficulty breathing or shortness of breath or wheezing
  • swelling of the mouth, throat or tongue
  • rash
  • itching – usually around your eyes, ears, lips, throat or roof of the mouth
  • flushing (feeling hot and red)
  • stomach cramps, nausea &/or vomiting
  • feeling weak
  • collapse or unconsciousness.

Call triple zero (000) from a landline or 112 from a mobile for an ambulance. If the person has a ‘personal action plan’ to manage a known severe allergy, they may need assistance in following their plan. This may include administering adrenaline to the person via an autoinjector (an Epipen®) if one is available.

Adapted from an article at www.healthsure.com.au

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