Often, in the course of BLSD (basic life support and defibrillation), we emphasize the safety of the scene during the discharge of a defibrillator, often with examples of apocalyptic destruction of the entire human race or breaking the space-time continuum if someone touches patient during the discharge of the AED.
But is that really so? It is really so dangerous to touch a patient during the discharge of a defibrillator?
To find out, we can not trust hearsay, the cugggino who had a friend whose boyfriend was a Red Cross volunteer and once he heard of ... but we must rely on the scientific literature.
So let's start from 1990, a retrospective study carried out by Gibbs, Eisemberg titled "Dangers of defibrillation: injuries to emergency personell During patient resuscitation" published in the American Journal of Emergency Medicine.
In this study we analyze some problems highlighted during cardiopulmonary resuscitation in pre-hospital personnel of the state of Washington in the previous 10 years.
In particular are reported eight cases where there was contact between the patient and an operator during the download of the AED.
Remembering that we are in the late 80s and early 90s of the last century ( ) And then with an obsolete technology today, we see the eight cases highlighted.
Case no. 1 (the worst), during defibrillation, a plate that integrates seemed instead was broken and exposed, on the outer surface, part of the electrical circuitry inside. At the defibrillator operator received, in full, the discharge and lost consciousness for a few minutes. E 'was necessary to hospitalize the operator which was then kept under observation for three days and treated with lidocaine for the premature ventricular contractions.
Case no. 2, the arm of a health care was touching a metal part of the stretcher during discharge. The operator reported tingling in the arm for 30 minutes
Case no. 3, the hand of an operator was in contact with the gel during defibrillation. Mild soreness of the arm
Case no. 4, a paramedic was taking a femoral pulse while another defibrillated. The operator was thrown from the discharge but did not report any problems later.
Case no. 5, the leg of a paramedic was touching the patient. The operator reported feeling a slight shock to the leg.
Case no. 6, the paramedic was keeping the bag mask on the face of the patient. The operator reported feeling a slight shock on my fingertips.
Case no. 7, the thumb of the paramedic was in contact with the patient's chest. The operator has been lethargic for several minutes and then fully recovering
Case no. 8, the leg of a health care was touching a metal part of the stretcher during discharge. The operator reported hearing a shock to the leg
Eight cases in ten years, where, in the worst case, the operator was found in direct contact with a bare wire defibrillator but where, however, after a hospitalization, reported no serious consequences as in the other eight cases.
Gibbs Eisemberg analyze and then the other 13 cases occurred between 1984 and 1987 reported to the Food and Drug Administration with issues related to
1. Problems defibrillator
- A defibrillator that was downloaded during charging
- A defibrillator that was downloaded while performing an ECG
- Download spontaneously without the operator had pressed any buttons
- Operator receives download in the moment it touches the discharge button
- An operator receives a discharge while he was repairing an AED
2. Operational Problems
- Overlapping plates
- Operators touch the patient during the discharge
In each of these cases there were no consequences except in cases of overlapping plates where patients and sometimes operators have suffered burns due to the combustion of the plates, the gel produced by or caused by the electric discharge.
A final case reports treated to an instructor during a lesson in ALS (advanced life support), he finished the game for the plates of a defibrillator at the temples and, without realizing that the defibrillator was loaded, pressed the button to download .
The operator was knocked to the ground and was unconscious for 5 minutes and for the next 36 hours was lethargic. The operator holds a retrograde amnesia and a second-degree burn on his face. But even in this case, "extreme", the recovery was complete and there were no consequences for the future.
The study of 1990 ended with the need to increase the training of workers on safety procedures and on making the scene that actually nobody is touching the patient because if it is true that in the cases identified, the consequences were minimal, safety operators is of paramount importance for proper cardiopulmonary resuscitation.
But let's get to today. The study above was, as mentioned retrograde study, which was based on accidental cases have already occurred and without the presence of an adequate control over the operating conditions in which they occurred.
How to see what happens in a controlled environment, if I touch the patient while a defibrillator is downloading? And 'possible to make a study plan to the discharge of an AED on a patient and measuring the current through a rescuer who is massaging?
And 'what they did Lloyd, Heeke, Walter and Langberg in a study entitled "Hands-on defibrillation: an analysis of electrical currency flow through rescuers in direct contact with patients During bifasic external defibrillation" published in 2008 in Circulation that says far from the title.
Ridiciamolo in Italian, "Analysis of current through rescuers in direct contact with patients during biphasic shock from an external defibrillator." Wow.
What did these gentlemen? Obviously not being able to know when it could happen any where cardiopulmonary resuscitation, they used a different approach.
Given that the defibrillator is also used to cardiovertire atrial fibrillation in a conscious patient, and this is an event not urgent but ambulatory and then you will know when and where they will be asked 39 patients with atrial fibrillation to be used as guinea pigs.
But the guinea pigs but they really were not many volunteers who were asked to simulate a "slight" heart massage on these patients, and to be in contact with the skin of the patient, while 43 defibrillator discharges Lifepac 12 .
Again, maybe it is not clear, these rescuers have caught 43 defibrillator discharges without ever leaving the patient's chest and continued to massage.
Not happy with the electrical contact between patient and rescuer have to allow the return of current between rescuer and patient, inserted with the electrodes, a 110 kOhm resistor in parallel and in series with a 120 Ohm between the leg and the back of the rescuer patient thus realizing the following electrical circuit.
To measure the current that passed through the body of the rescuer has received a two-channel oscilloscope on the heads of the two resistors.
They were then paid 4 shock of 100 Joules, 27 Joules 200 and 8 360 Joules.
NONE OF THESE DOWNLOADS ARE PERCEIVED BY OPERATORS
The currents measured by the oscilloscope were always lower than the average mAmpere with a passage of energy through the body of the rescuer of the order of microjoules.
Result, all discharges were not only below the threshold of perception, but many in the U.S. under the recommended values for the output, in trade, to eletric devices.
Ultimately, with all the caution of the experiment, the operators were subjected to currents lower than those that can be taken by touching the knobs or electrical contacts to a computer, radio, television and other electrical equipment properly shielded and meet the specifications.
The conclusions of the article are that, given the emphasis made in the latest guidelines on the quality of CPR and they do not break, given the low levels of exposure to currents delivered during the discharge, you might think the elimination of the times " dead "CPR during charging and discharging of the DAE.
Ultimately, it is said that, in one or two revisions of the guidelines, we are not left to massage all of the AED during the discharge, contrary to the doomsday scenarios that tell so far.
But let's see what happened after the release of this study.