how good is your precordial thump?

7 Nov

HOW STRONG IS YOUR THUMP?

tough finding data on this (if you find more, please send it my way):

one study with 2 cardiologists:

  • cardiologist 1: 6.3–7.1 J
  • cardiologist 2: 8.8–10.4 J
  • ventricular arrhythmia terminated in only 2/155 patients

defib-thump

The Good:

deliver mechanical force to attempt defib (see mechanism below)

you can’t kill dead (little downside, aside from possible trauma, depending on strength)

 

The Bad:

if its not v-fib, and you induce it with an R-on-T

rarely successful (0/180 successful thumps with fist or 30-40mph lacrosse balls in one study)

The Mechanism (theory):

  • conversion of mechanical energy to electrical current (mechanoelectric coupling)
  • initiated by chest impact with a rapid, transient rise in left ventricular pressure.
  • Increased pressure results in myocardial stretch
  • stretch-activated ionic channels including the K+ATP channels are activated and open, resulting in an inward current and subsequent depolarization.

In commodio cordis, this depolarization induces a premature ventricular beat which, if precisely timed during the upstroke of the T wave in the P-QRS-T electrical cycle, can result in ventricular fibrillation—in essence, the R-on-T phenomenon.

In intentional precordial thump, this depolarization can indeed defibrillate the myocardium and thus interrupting the ventricular dysrhythmia.

References: cardiologist thumps; lacrosse ball thumps + picture;  mechanism

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