Short-timers in today’s workplace?

Working the last few years in a larger organization has made me aware of the fleeting thinking of the aging workforce. It may be due to my career progression that I have just recently realized that many of my peers and even those reporting to me will be retiring in the next decade if not sooner; or maybe working in smaller startup organizations drew on a different working population – I’m not sure. What’s important here is that I never noticed it before and now it is obvious to me. I’d like you to understand that working with those that have birthdays before mine is not an issue, quite the opposite, they have a world of experience and tacit knowledge that I think will be a loss once they depart. I’ve even managed to control that short termed decision making, since the decisions that my short term colleagues make today will not be their problems tomorrow (they will be my problems.) But an outside vendor today, underlined the diminished benefit of short timers’ thinking.

In the engineering world, especially in systems and electronics there is a symbiotic relationship between company component vendors and designers. When designers need parts, support, they call on those representatives. The representatives need to forge relationships with the designers to facilitate the use of those parts in designs. These representatives come and do presentations on upcoming technologies, what they have in the pipeline, technology trends etc. It’s mutually beneficial for the designers and the representatives. Today, one of these reps displayed off of his computer a great presentation. On top of the screen, what was at first a curiosity was a timer counting away. As the conversation progressed my curiosity was satisfied in learning that the timer was a retirement counter, which counted the retirement year down to the second. Now, as a representative for a going concern, fostering a relationship that is supposed to last for years with a potential customer – why would you want to communicate to that individual “I’m knowledgeable and can support you designing these parts, but this knowledge and support will be gone soon.” My design cycles last years (and these guys know it) I don’t want to be left in the dark when I’m half way through a design.

I realize that this is a life changing event for the representative, and that the display of a clock was not malicious, but in good spirits (at least his good spirits.) Am I being over sensitive? This isn’t a matter of ageism it is a matter of professionalism.

History of Defibrillation

The History of defibrillation most notably started in the in 1775 when Peter Christian Abildgaard, a Danish veterinarian and physician, conducted experiments on electrical countershock on animals. He succeeded in first rendering fowl lifeless by an electric shock and then reviving them by a countershock applied to the chest. Ventricular fibrillation and defibrillation were not known and could not be documented at that early date, but his report suggests he accomplished these changes long before other physiologists described them.  (Driscol TE, 1975)

A century later in 1899, Jean-Louis Prévost and Frederic Batelli, two physiologists at the University of Geneva, revived animals with a capacitor discharge delivered directly to the heart. Decades later, one of their graduate students, Lina Schtern, moved back to the Soviet Union and continued to work on the technique. A student of Schtern’s named Naum Gurvitch persisted with the method of defibrillation. He was the first to suggest using a biphasic waveform, publishing a short article in 1942 on his use of biphasic shocks to resuscitate animals, but the idea didn’t really take hold until much later.

Circuit Diagram of the Prevost Batelli Defibrillator

At the same time Schtern and later Gurvitch were working with Prevosts technique, a physician at Beth David Hospital of New York, Dr. Albert S Hyman and an Electrical Engineer C. Henry invented the Hyman Otor. This invention was  a Self Starter for the Dead Man’s Heart as featured in Popular Science in 1933. “This life saving device can be compared with the self-started of a car. When the car’s engine stalls, the starter motor turns it over until all cylinders are again firing. In the same way, when the heart stops…the needle of the Hyman Otor, as it is called, gives the four cylinder heart engine a rhythmical electrical stimulation. This starts the heart beat and maintains it until the hearts own electrical generator resumes operation.” (Physician Invents Self Starter for Dead Mans Heart, 1933)

Article page from Popular Science (Physician Invents Self Starter for Dead Mans Heart, 1933)

During this time the world was going through rapid industrialization. Transmitted electricity was poised to revolution life as we know it. At the time, very little was understood about the dangers associated with electrocution.  Companies installing electricity to new customers noticed that many of their utility linemen suffered from a high number of electrical shocks and accidental deaths. Starting in the 1920’s Consolidated Edison (Con Edison) power company funded research in several Universities to understand the lethalness of electricity and what can be done to prevent it.

One of those researchers was William Kouwenhoven an Electrical Engineering professor at Johns Hopkins. He started his work on rats in the 20’s and later in 1934 discovering a method of heart re-starting (defibrillation) on dogs.  The first use on a human was in 1947 by Claude Beck, professor of surgery at Case Western Reserve University. Beck's theory was that ventricular fibrillation often occurred in hearts which were fundamentally healthy, in his terms "Hearts that are too good to die", and that there must be a way of saving them. Beck first used the technique successfully on a 14 year old boy who was being operated on for a congenital chest defect. The boy's chest was surgically opened, and manual cardiac massage was undertaken for 45 minutes until the arrival of the defibrillator. Kouwenhoven’s open chest defibrillator, later used at John Hopkins as standard treatment for cardiac arrest, was based on AC current passed through a transformer to increase the voltage.

Until the mid 1950’s the only means of defibrillation was when the chest cavity was open. It wasn’t until 1955 and 1956 when closed chest defibrillation was pioneered by Dr. V Eskin in the USSR and Dr. Paul Zoll from the US working independently from each other. They were able to successfully defibrillate patients by placing the electrodes on the chest wall itself. The basis of Eskin’s and Zoll’s closed chest defibrillators remained AC electrical voltage. It wasn’t until 1959 when cardiologist Dr. Bernard Lown, built the first DC defibrillator

Circuit Diagram of the Kounhoven Zoll defibrillator

Claude Beck and James Rand 1947 Open Chest defibrillator

Paul Zoll's closed chest defibrillator

Lown charged a bank of capacitors to approximately 1000V with energy of 100-2000 joules and delivered the charge through a large inductance, producing a heavily dampened sinusoidal wave.  Berkowitz, an engineer developed the defibrillator into a clinical application known as the “cardioverter” in 1960. The Lown waveform was used in defibrillation for the next few decades.

The Lown DC capacitor based defibrillator

Dr. John Schuder over the period of 60’s – 80’s performed a number of studies on the waveform used for defibrillation. (Gold JH, 1977) (SCHUDER JC, 1966) In 1980 he concluded that the biphasic waveform was superior in defibrillation effectiveness. (Schuder JC, 1982) (Schuder JC M. W., 1984)

Trapezoidal waveform defibrillator

An H-bridge circuit topology of a biphasic type defibrillator

In 1996, an AED using an impedance-compensating biphasic truncated exponential waveform, introduced by Heartstream, now a part of Philips Medical Systems, was approved for use by the FDA.  Following the introduction of the biphasic waveform, the American Heart Association’s Guidelines in  2000 (AHA, 2000) affirmed evidence of the safety and efficacy of the biphasic waveform for termination of ventricular fibrillation. A notable benefit in sustaining a constant current during the first phase in the biphasic waveform ZOLL Medical introduced the rectilinear biphasic waveform. (White, New concepts in transthoracic defibrillation, 2002)

Circuit topology of the ZOLL Rectilinear biphasic waveform

Several other biphasic with slightly different morphologies are available for clinical use and have shown to achieve greater efficacy in terminating short-duration VF compared to the monophasic predecessor.  (White, New concepts in transthoracic defibrillation, 2002) (White, 2004)

Defibrillation waveforms of the different historical defibrillators

During this time, advancements in microprocessor technology allowed for the development of the portable Automatic External Defibrillator (AED.) The first AED was marketed by Cardiac Resuscitator Corporation and it integrated automatic analysis of heart ecg signals and automatically delivered a defibrillation.

The AED circuit diagram

In 1991 the American Heart Association recognized the benefit of life saving AED and launched a Public Access Defibrillation Initiative. The population of AEDs has grown from 15,000 in 1990 to 1.6million in 2009. (Shah JS, 2006)

Recent developments in Defibrillation

In 2002 the FDA approved a wearable defibrillator by Lifecore, now part of ZOLL Medical. The wearable defibrillator is worn by patients at risk for sudden cardiac arrest, providing protection during their changing condition and while permanent treatment is sought.

In 2004 the FDA approved an over the counter defibrillator, on data indicating that a large number of cardiac arrest happens in the home. The move has been controversial, but the defibrillator remains on the market. (Eisenberg, 2005)

Seeing the Forest for the Trees: The FDA's Myopic View of AEDs and Public Health

In the past few months the US Food and Drug Administration has launched a Medical device Innovation Initiative to address the Automated External Defibrillator, or AED in order to “improve these technologies so that we can save more lives” as said by the Director of the FDA’s Center for Devices and Radiological Health (CDRH,) Jeffrey Shuren M.D. What the FDA fails to understand that the defibrillator is a unique medical device that treats a patient that is collapsed and considered expired; the timely presence of an AED facilitates a small percentage chance of survival after collapse, not an assurance of survival. A higher proliferation of AEDs – driven by economics and secondarily accessibility increase the chances that an AED is available in locations that cardiac arrest can occur. With the FDA’s proposed higher regulation of AEDs will increase costs, lower innovation and consequently decrease the numbers of AEDs. This will lower the chances of a timely defibrillation with an AED and as a result increase the numbers of deaths due to sudden cardiac arrest, defeating the increases in survival seen over the last couple decades. The FDA is creating an unintended consequence with this initiative and instead of promoting public health is diminishing public wellbeing. The FDA would be best to foster public health by allowing manufacturers to lower costs with less regulation and higher industry innovation, thus escalating AED proliferation and increasing, statistically, survival of citizens collapsing from cardiac arrest.

Background

In 1775 Peter Christian Abildgaard, a Danish veterinarian and physician, performed experiments on chickens; he showed that he could make chickens lifeless with an electrical impulse passed through the body, and he could restore a heart pulse with a second impulse if it was passed across the chest. Though Abildgaard did not document this as inducing ventricular fibrillation and subsequently defibrillation – it is arguably the first use of an external defibrillator. (Driscol TE, 1975) Centuries later, the essence of defibrillation is the same, an electrical impulse is passed through the chest, and a lifeless body (from cardiac arrest) is revived. This is one of the exceptional characteristics of the defibrillator – the patient being treated is lifeless.

Since Abildgaard’s time the medical community has become much more learned as to the mechanisms that he observed on his fowl. It is thought that by shocking the hens with electricity he caused ventricular fibrillation; consequently by following with a counter shock he defibrillated making the heart contract correctly instead of twitching. Ventricular fibrillation (or VF) is known to be the cause of sudden cardiac arrest and sudden cardiac death. It is a condition of uncoordinated contraction of the ventricular cardiac muscles causing the heart to tremble instead of contracting properly. The underlying cause of VF is not completely understood, and the symptoms of VF and subsequently cardiac arrest and death can occur in what would be considered a healthy heart.

Cardiac arrest is a leading cause of death in the United States and accounts for 300,000 to 400,000 deaths per year.  (Shah JS, 2006) (Sachdev M, 2010)  Ventricular Fibrillation is the initial rhythm in approximately 30% of cardiac arrests thereby accounting for 100,000 such events yearly in the US. (Sherman LD, 2008) Sudden Cardiac Arrest is not a heart attack by definition. A heart attack is myocardial infarction, which is caused by a blockage in the arteries to the heart muscle causing ischemia, in other words restriction of blood flow and in turn oxygen shortage which causes death or infarction of the of the heart muscle tissue – the myocardium. Sudden Cardiac Arrest can be caused by a heart attack, but the underlying mechanism of the cardiac arrest is the cessation of the cardiac muscles to contract properly, the heart will quiver as an example in cardiac arrest. The defibrillator is the only device to counteract this killer.

Defibrillation and the AED

The advent of defibrillator started in the 1920’s with funding from Consolidated Edison (Con Edison) the power company. Con Edison was concerned with the high number of electrical shocks and accidental deaths occurring to their line men. The first external defibrillations where performed in the 50’s, the AED was an advent in the 80’s when computer analysis of heart Electrocardiogram (ECG) was combined with defibrillation – allowing for a device to analyze the heart rhythm and if the heart signal is one that can be defibrillated, the AED delivers the appropriate electrical impulse.

The American Heart Association recognized the importance of the AED and in 1991 the AHA issued a challenge to manufacturers to develop simple, low-cost automatic defibrillators for use where large numbers of people congregate. Since then, considerable advances have occurred, and several manufacturers have developed small, lightweight, simple semiautomatic external defibrillators (AEDs) for use by the public. (Cobb LA, 1992)

The number of AEDs in use has grown from 15 thousand in 1996 to 1.65 million in 2009. (Shah JS, 2006) Data collected over the time that AEDs have been available show that more than 95 percent of cardiac arrest victims die before reaching the hospital. More importantly, in cities where defibrillation was provided within 5 to 7 minutes, the survival rate from sudden cardiac arrest was as high as 30–45 percent. (AHA, 2011) (Eisenberg MS, 2009) The most important determinant of successful return to circulation is the time interval from onset of ventricular fibrillation to initial intervention. The time from onset of VF to defibrillation is the key element in the acute management of the cardiac arrest victim. The chance of survival decreases 7% to 10% for each minute that defibrillation is delayed as shown in the figure below. (O'Rouke) (Calans, 2004) Defibrillation alone often results in successful resuscitation if delivered four minutes of cardiac arrest. (Calans, 2004)

Figure 1 Exponential Decline in Rate of Survival after Sudden Cardiac Arrest as Time to Defibrillation Increases (Calans, 2004)

Public Access Defibrillation

“Public Access Defibrillation (PAD), which places AEDs in the hands of trained laypersons, has the potential to be the single greatest advance in the treatment of ventricular fibrillation cardiac arrest since the development of the CPR.”  (AHA, Guidelines 2000 for Cardiopulmonary Resuscitadon and Emergency Cardiovascular Care. Part 4: the automated external defihrillaror: key link ill the chain of survival, 2000)

Walking in Chicago O’hare Airport from ticket counter to the terminal, one will encounter multiple AED’s along the way. This was an intentional installation placing AEDs 60-90 walk/seconds apart from each other. The City of Chicago started this program in 1999, placing highly visible AEDs for public use at O’hare and Midway as part of the Chicago Heart Save Program sparked from the PAD program. (Caffrey, 2002) The airports serve over 100 million passengers per year; in a two year period 21 persons had cardiac arrest – 18 of which had ventricular fibrillation for which an AED can be used. Of those 18 people, 11 where successfully resuscitated – over 61%. In comparison the survival rate across the United States is 5%. (Caffrey, 2002) The study concluded that AEDs placed in readily accessible, well marked public areas are effective in assisting patients with cardiac arrest. (Caffrey, 2002) It is the abundance of AEDs in a populated area that increase public health.

The FDA’s role in AEDs

FDA’s mission is to protect and promote public health, in 1976 under the Federal FD&C Act the regulatory controls for medical devices was established. Under this Act, the FDA established a three tiered risk based classification. The lowest risk level is Class 1 and products in this class are things such as tongue depressors, sterile gloves etc. where the patient risk is low. Class 2 products are things such as contact lenses, patient monitors and manual defibrillators.  Class 3 products are those that are of highest risk such as stents and artificial hearts, where the risk to patient is the highest. Due to the innovative quality of the AEDs, they were given a Class 3 designation when they were determined to be substantially equivalent to similar Class 3 devices that were on the market. Market approval to sell devices is based on this classification system.

In general there are two routes to obtain market approval on a medical device. One is what is called the 510(k), designated for the section of the regulation. In this process the manufacturer demonstrates equivalence to products that are already on the market. This pathway is typically reserved for Class I and Class II devices, but which has also been used for some Class III devices that were allowed to be reviewed under the 510(k) regulations until reclassified or determined to require a Pre Market Approval. The second pathway, designed for riskier products is the Pre Market Approval (PMA) process – which to manufacturers generally means clinical trials to establish safety and efficacy, a costly proposition.

AEDs have always been regulated through the 510(k) process. According to a 1990 amendment to the 1976 legislation, the FDA must either down-classify AEDs to Class II or keep AEDs as Class III and require they go through the more PMA process. The FDA is now proceeding with the formal classification of AEDs. During this time since AEDs have come on the market to today, manufacturers have demonstrated the efficacy of the AED, they have shown to ability to meet demands for the product which was driven by effective saving of lives. Why would the FDA counteract this obvious public benefit?

The FDA is concerned with the number of adverse reports concerning AEDs. As stated by the FDA, “during the past five years, the FDA’s CDRH has received more than 28,000 medical device reports associated with the failures of external defibrillators and manufacturers conducted dozens of recalls involving hundreds of thousands of the devices.” In a study by Dr. Jignesh Shah in the Journal of American Medical Association, 2.78 million AED device years where observed from 1996 - 2005. In that time 21.2% of the AEDs distributed were recalled, due to electrical or software problems. The author concluded that “AED advisories occur frequently and affect many devices. Actual AED malfunctions do occur occasionally, although the number of observed malfunctions is small compared with the number of lives saved by these important devices. As the prevalence of AEDs continues to increase, the number of devices affected by advisories can also be expected to increase. Efforts should be directed at developing a reliable system to locate and repair potentially defective devices in a timely fashion.” (Shah JS, 2006) The prevalence of adverse reports has not changed over the last couple decades, and as demonstrated in this study malfunctions can occur, but the rate of occurrence is much smaller than the number of lives saved.

It is fundamental in the AED business to fix problems as they are identified. AED manufacturers are obliged to identify problems, file them with the FDA as Medical Device Reporting (MDR). The FDA compiles this data into a database of Adverse Event Reporting. Adverse reports can also come from the general public, but in the case of AEDs only 2% come from the public 98% of the adverse reports are from the manufacturers themselves. The manufacturers are identifying problems and fixing them as they arise.

Figure 2 Slide from the FDA AED meetings. Over 98% of Adverse Reports come from manufacturers and a very small number from user facilities such as hospitals. (Sullivan, 2010)

Similar to the FDA’s actions in the mid 90’s Laerdal identified a problem with a component, recalled devices without affecting customers and filed a Medical Device Reporting (MDR) with the FDA per the regulation – noted as an adverse event report. The FDA acting with little comprehension issued a safety alert on that AED device. (Cummins RO, 1995) How many cardiac arrests did the FDA adversely affect due to its uninformed choices? How many people will die from cardiac arrest tomorrow because of FDA’s actions today?

The increase of adverse events, as noted by Shah, will also increase with the number of AEDs in circulation. (Shah JS, 2006) Taking the data of AED population and folding over the FDA data of adverse data reports one can identify that the number of adverse reports has the same trend as predicted by Shah.

Figure 3 AED Population with data derived from FDA and Shah, with FDA adverse events that where available plotted. (Shah JS, 2006) (Sullivan, 2010) The trend in the number of adverse events is related to the population of AEDs and not a lower quality of devices.

The same trends in as seen in 2004 are seen in 2008 in terms of percentage of adverse reports. This should not be a factor in the FDA’s decision to reclassify the AEDs. Instead The FDA should focus on the benefit to the public with having a large population of AEDs in circulation and what percentage of the public will continue to live because there was an AED at hand. Reclassifying the AED, forcing manufacturers to go through a PMA will drive up AED costs. In the FDA NEWs website the news blurb read – “In a move that could cost device makers millions of dollars, an FDA advisory panel has backed the agency’s proposal to classify automated external defibrillators (AEDs) as Class III devices that must go through the PMA process” (FDA News, 2011) It’s not the device makers that will absorb that cost – that cost will be passed on to the end customer – a customer with a fixed budget to purchase AEDs for their casinos, churches, gyms... Does one need anything more than common sense to determine that the end customer will buy fewer devices if they are more expensive? It is common sense that with fewer AEDs more people will unnecessarily die.

“The FDA managers may need to take a long hard look at the actions of the agency and consider that through the shortsighted actions the FDA itself may be considered a serious danger to, and not a watchdog for our nation’s public health. “ (Cummins RO, 1995) The FDA has myopic vision and does not see the forest for the trees. It is of greater public wellbeing for the FDA to down classify AEDs to the same level as their cousins the defibrillators – it is the numbers of AEDs that save lives.

Works Cited

AHA. (2011, 03 01). Cardiac Arrest. Retrieved 03 01, 2011, from American Heart Association: http://www.americanheart.org/presenter.jhtml?identifier=4481

AHA. (2000). Guidelines 2000 for Cardiopulmonary Resuscitadon and Emergency Cardiovascular Care. Part 4: the automated external defihrillaror: key link ill the chain of survival. Circulation , 160-167.

Caffrey, S. (2002). Feasibility of public access to defibrillation. Curr Opin Crit Care , 8 (3), 195-198.

Calans, D. (2004). Out of Hospital Cardiac Arrest - The Solution is Shocking. New England Journal of Medicine , 632-634.

Cobb LA, E. M. (1992). Report of the American Heart Association Task Force on the Future of Cardiopulmonary Resuscitation. Circulation , 85, 2346-2355.

Cummins RO, W. R. (1995). Ventricular fibrillation, automatic external defibrillators, and the United States Food and Drug Administration: confrontation without comprehension. Ann Emerg Med , 26 (5), 632-631.

Driscol TE, R. O. (1975). The remarkable Dr. Abildgaard and countershock. The bicentennial of his electrical experiments on animals. 83(6).

Eisenberg MS, P. B. (2009). Defining and improving survival rates from cardiac arrest in US communities. JAMA , 301 (8), 860-862.

FDA News. (2011, 02 01). FDA News Bulletin - Panel: AEDs Should Stay Class III and Be Subject to the PMA Path. Retrieved 03 01, 2011, from FDA News: http://www.fdanews.com/newsletter/article?articleId=133873&issueId=14426

O'Rouke, R. (n.d.). Saving Lives in the Sky. Correspondence to Robert A. O'Rourke, MD, Charles Conrad Brown Distinguished Professor in Cardiovascular Disease .

Sachdev M, F. B. (2010). Failure in short-term prediction of ventricular tachycardia and entricular fibrillation from continuous electrocardiogram in intensive care unit patients. J Electrocardiol , 43 (6), 400-7.

Shah JS, M. W. (2006). Recalls and safety alerts affecting automated external defibrillators. JAMA , 296, 655-660.

Sherman LD, R. T. (2008). Logarithm of the absolute correlations of the ECG waveform estimates duration of ventricular fibrillation and predicts successful defibrillation. Resuscitation , 78 (3), 346-354.

Sullivan, R. (2010, 12 15). Adverse Event Reporting-presentation. FDA Public Workshop on External Defibrillators, December 15-16, 2010 . Silver Spring, MD, USA: FDA.