次の英文の和訳をお願いしたいです。
An automated external defibrillator (AED) is a portable electronic device that automatically diagnoses the life-threatening cardiac arrhythmias of ventricular fibrillation and ventricular tachycardia in a patient, and is able to treat them through defibrillation, the application of electrical therapy which stops the arrhythmia, allowing the heart to reestablish an effective rhythm.
With simple audio and visual commands, AEDs are designed to be simple to use for the layperson, and the use of AEDs is taught in many first aid, certified first responder, and basic life support (BLS) level cardiopulmonary resuscitation (CPR) classes.
An automated external defibrillator is used in cases of life-threatening cardiac arrhythmias which lead to cardiac arrest. The rhythms that the device will treat are usually limited to:
1.Pulseless Ventricular tachycardia (shortened to VT or V-Tach)
2.Ventricular fibrillation (shortened to VF or V-Fib)
In each of these two types of shockable cardiac arrhythmia, the heart is electrically active, but in a dysfunctional pattern that does not allow it to pump and circulate blood. In ventricular tachycardia, the heart beats too fast to effectively pump blood. Ultimately, ventricular tachycardia leads to ventricular fibrillation. In ventricular fibrillation, the electrical activity of the heart becomes chaotic, preventing the ventricle from effectively pumping blood. The fibrillation in the heart decreases over time, and will eventually reach asystole.
AEDs, like all defibrillators, are not designed to shock asystole ('flat line' patterns) as this will not have a positive clinical outcome. The asystolic patient only has a chance of survival if, through a combination of CPR and cardiac stimulant drugs, one of the shockable rhythms can be established, which makes it imperative for CPR to be carried out prior to the arrival of a defibrillator.
Uncorrected, these cardiac conditions (ventricular tachycardia, ventricular fibrillation, asystole) rapidly lead to irreversible brain damage and death, once cardiac arrest takes place. After approximately three to five minutes in cardiac arrest, irreversible brain/tissue damage may begin to occur. For every minute that a person in cardiac arrest goes without being successfully treated (by defibrillation), the chance of survival decreases by 7 percent per minute in the first 3 minutes, and decreases by 10 percent per minute as time advances beyond ~3 minutes.
AEDs are designed to be used by laypersons who ideally should have received AED training. However, sixth-grade students have been reported to begin defibrillation within 90 seconds, as opposed to a trained operator beginning within 67 seconds. This is in contrast to more sophisticated manual and semi-automatic defibrillators used by health professionals, which can act as a pacemaker if the heart rate is too slow (bradycardia) and perform other functions which require a skilled operator able to read electrocardiograms.
Bras with a metal underwire and piercings on the torso must be removed before using the AED on someone to avoid interference. American TV show Mythbusters found evidence that use of a defibrillator on a woman wearing an underwire bra can lead to arcing or fire but only in unusual and unlikely circumstances.
A study analyzed the effects of having AEDs immediately present during Chicago's Heart Start program over a two-year period. Of 22 individuals 18 were in a cardiac arrhythmia which AEDs can treat (Vfib or Vtach). Of these 18, 11 survived. Of these 11 patients, 6 were treated by bystanders with absolutely no previous training in AED use.
お礼
ご回答ありがとうございます。とても自然な訳をご提示頂き、感謝しています。僕の訳が稚拙すぎて、恥ずかしい限りです。 追加で質問させて下さい。「who has experienced a witnessed, out-of-hospital cardiac arrest」の訳なのですが、回答者様は「院外発作を経験したか目撃した」と訳されていました。この「witnessed」は過去分子形で「cardiac arrest」を修飾する、と僕は思ったのです。それ故、「病院の外で目撃された心臓発作を経験した」⇒「病院の外で心臓発作を目撃した」という訳に辿り着きました。回答者様はこの「witnessed」は何だと思われますか？