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Old 14 July 2015, 20:11
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A little do-da I posted elsewhere.

A few ruminations on repetitive exposures to primary blast.

Quote:
Blast ovepressure (BOP) injury to the lungs alone, without secondary trauma will be extremely difficult, perhaps impossible diagnosis for the combat medic to make. If he knows the mechanism of injury he may begin to look for extremely subtle signs and symptoms that the patient will begin to display. One of the first perceptible signs that the medic will be able to note is increased respiratory rate. This will soon be followed by increased cardiac rate. Because of the nature of combat these subtle signs can easily be overlooked, especially in the absence of secondary trauma. The severity of the lung injury will determine the speed of onset for later signs and symptoms. As the condition worsens the patient will begin to display more serious signs of respiratory distress:

Shortness of breath
Pulmonary edema
Unequal breath sounds bilaterally
Worsening hypoxia, falling SpO2
Altered LOC (level of consciousness)
Hyporesonance of the chest to percussion

Past studies have been conducted which looked at repetitive exposure to low level blast effects. A 1978 paper titled “Damage-risk criteria for personnel exposed to repeated blasts” by Richmond, Yelverton and Fletcher considered this, they found that the Larynx, Gastrointestinal Tract, and Lungs were at increased risk with repeated exposures. A more recent study looked at the same effect utilizing a repetitive exposure /urban combat test scenario.

In this test, a munition was located in the primary room of test structure, a bio-mechanical model was positioned in an adjacent secondary room and received 5 repetitive low level exposures to primary blast, the exposures occurred at 15 minute intervals, replicating to what military members might experience during urban house to house battle. Following the 5th exposure a necropsy was performed and defuse bi-lateral petechial hemorrhage was found on the lungs, no injury to the gastrointestinal tract or larynx was noted. Additionally, post exposure assessments (pre-euthanization) did not reveal: apnea, tachypnea, bradycardia, hemoptysis or a dramatic shift from the pre-exposure baseline vitals.

It should be noted that this scenario was designed to replicate an operational environment only, the bio-mechanical model was not fitted with protective material replicating body armor or a helmet.

Can a correlation be made between low level repetitive exposure of lung tissue and the brain? In the test discussed above a single low-level exposure produced no macroscopic lung damage, I’m assuming because dose was sub-threshold. That said, 5 repetitive exposures of the same approximate explosive dose did. Did the threshold of injury shift? Could the same hold true to for brain?

That said, I submit a reasonable “hypothetical” training scenario for SOF soldiers.

YOU are the junior medic on your ODA. Your team is at the heavy weapons range conducting training which consists of firing Carl Gustaf 84mm recoilless rifles, AT-4’s and LAW’s. You have administrative range support providing medical coverage and range safeties. The team receives the safety brief from the range safety officer. The training plan includes firing all 3 weapons systems from numerous firing positions - standing, kneeling and prone. The remainder of the training proceeds without incident, approximately 65 weapons were expended during training. All range safety rules were followed, it was a good day at the range.

Post range: Back at the team-room several of your team mates tell you that they’ve got headaches and nausea. All paxs involved feel that their symptoms were due to wearing helmets all day and or slight dehydration but could they be symptomatic for a mTBI . They all want you to hurry up and give them some meds so they can go home, several of the guys are cross training with another team the next day conducting CQB and breaching.

Since you are conducting CONUS training, environmental sensors providing a quantifiable blast exposure data were not available.

As the medic, what do you suspect and what are you going to do?

How do you know if dehydration and wearing the helmet is the reason for the symptoms, or did a mild concussive injury occur?

Any concerns about them breaching the next day?

Well, what’s you plan Medic?
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Old 14 July 2015, 21:07
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Ha, this got re-posted on my LinkedIn feed about 20 minutes after I read it here. Well written article sir.
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Old 15 July 2015, 13:51
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I’m thinking that first I’d get a solid set of vitals and question the guys about fluid intake and urine output (quantity, color/consistency). Also ask them about similar occurrences (ie. last time they wore a helmet in the heat all day what did it feel like - if they remember).

Would also use the mTBI metric to establish and compare to previous baseline just in case.

If initial vitals were all good to go, I’d instruct them to take down 50/50 Gatorade/water mix PO and get into a cool environment.

Without loss of consciousness, I’m not overly concerned at this moment, but I would ask them to check in with me at least via telephone in 1 hour and 4 hours from time now.

If symptoms subside during those timeframes, I would be OK clearing them for training the following day after an AM eval, vitals, and repeat mTBI metric if all WNL.

If symptoms don’t subside, or if they worsen, or mTBI metric is way-off, I would recommend no breaching next day and have them follow-up with PA/DO/MD.

- Any thoughts? Feedback? -
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Old 15 July 2015, 16:11
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What that guy (O Pos) said.
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Old 15 July 2015, 18:04
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Quote:
Originally Posted by O_Pos View Post
If symptoms don’t subside, or if they worsen, or mTBI metric is way-off, I would recommend no breaching next day and have them follow-up with PA/DO/MD.

- Any thoughts? Feedback? -
I had two objectives when I wrote that, one is linked to the use of blast gauges because it can provide some insight into exposure to primary blast. They don't diagnose crap but that can you you (and the individual) something quantifiable, a relative blast dose.

Secondly, several of the symptoms of mTBI are common to playing "Army games".

I think that you're tracking with your plan. The "reverse digits" portion of the MACE be a good screening tool. From my perspective, if the dude is still symptomatic the next day or following he needs to be referred for eval.
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Old 16 July 2015, 13:32
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Quote:
Originally Posted by 24/7 View Post
...linked to the use of blast gauges because it can provide some insight into exposure to primary blast. They don't diagnose crap but that can you you (and the individual) something quantifiable, a relative blast dose.

Secondly, several of the symptoms of mTBI are common to playing "Army games"...
Touche'. I had never considered use of such gauges in a training environment. Very good idea indead.
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Old 16 July 2015, 19:47
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I'm an old guy. Never saw blast gauges and maybe the IDF still does not use them. When do you use them and what do they do for you? Is there a consensus regarding dose and anticipated effects?
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Old 20 December 2016, 14:07
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Originally Posted by 24/7 View Post
I had two objectives when I wrote that, one is linked to the use of blast gauges because it can provide some insight into exposure to primary blast. They don't diagnose crap but that can you you (and the individual) something quantifiable, a relative blast dose.
Update on the use of Blast Gauges:

"The Pentagon has quietly sidelined a program that placed blast gauges on thousands of combat troops in Afghanistan.

NPR has learned the monitoring was discontinued because the gauges failed to reliably show whether service members had been close enough to an explosion to have sustained a concussion, or mild traumatic brain injury.

But the small wearable devices did produce a trove of data on blast exposure that could eventually have helped researchers understand the links between bomb blasts, concussions and brain diseases. And they produced evidence that many service members are exposed to worrisome levels of blast pressure simply by being near a heavy weapon when it's fired."

Full article here: http://www.npr.org/sections/health-s...brain-injuries
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Old 20 December 2016, 17:18
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Quote:
Originally Posted by O_Pos View Post
Update on the use of Blast Gauges:

"The Pentagon has quietly sidelined a program that placed blast gauges on thousands of combat troops in Afghanistan.

NPR has learned the monitoring was discontinued because the gauges failed to reliably show whether service members had been close enough to an explosion to have sustained a concussion, or mild traumatic brain injury.

But the small wearable devices did produce a trove of data on blast exposure that could eventually have helped researchers understand the links between bomb blasts, concussions and brain diseases. And they produced evidence that many service members are exposed to worrisome levels of blast pressure simply by being near a heavy weapon when it's fired."

Full article here: http://www.npr.org/sections/health-s...brain-injuries
Of course they did. Why continue a program that would almost certainly cost them more money in veterans benefits once someone proves the link between blast pressure and TBI etc?
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Old 20 December 2016, 17:20
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Sorry, been too close to those research programs, development of the BG and transitioning the device to a user community, I would take the end result with a huge grain of salt...like the size of the moon. Basically I'm call BS on what DOD is doing.
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Old 20 December 2016, 20:46
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A couple of follow up comments.

  • Thresholds of injury are not firmly known and will change over time. If you've spent a career getting exposed to primary blast your threshold of injury will be lower than when you first began the walk.
  • Except for a few exceptions the BG's have not been used to record training exposures. They were deployed in AFG and Iraq.
  • BG's are absolutely reliable, there were compared to static gauge arrays and blast modeling programs.
  • Safe distances are have been determined based on mathematical computations, not actual data. Calculations don't bring peak reflected pressures into the equation. BG's collect all exposures over 4psi...provides quantifiable data.
  • With quantifiable data in hand and if a strong correlation is ever accepted that low level repetitive exposure does cause injury this will cost huge bucks on disability decisions.
  • If safe distance calculations aren't really safe then can you imagine what that means for training: i.e. breaching, heavy wpsn, arty, morters, range safety's.
  • I could go on but there's no value.
The only one that looses are the guys getting exposed.


This was developed, and it worked and I don't think the larger community was ready for the answers it lead too.

Been missing with this stuff since 2003, if pigs, sheep or goats are in Heaven I might be in trouble.
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Old 21 December 2016, 01:28
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Say someone was exposed to blasts ten year ago and say that someone was me. Is there any test I could do now?
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Old 21 December 2016, 02:47
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Was just listening to a former 18D talk about the blast guages on NPR yesterday morning. He was relating a story of a deployed soldier being diagnosed w/ a concussion after having fired a "rocket" of some kind(they didn't get into detail about the specific type of weapon) from inside an enclosed area. interesting stuff.
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Old 21 December 2016, 09:35
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Say someone was exposed to blasts ten year ago and say that someone was me. Is there any test I could do now?
Yes and No..most likely the later. Nothing that would say specifically that something now was connected to something then...unless you had a penetrating injury.

The beauty of the BG's is they allowed the wearer or medic to push a button on the gauge and determine if the blast produced enough over-pressure to possibly cause a injury. If yes, and dude is symptomatic then he needs to be seen by someone for more testing, if no symptoms - no action. The stuff I worked wasn't typical of DOD, we recorded all exposures so the dude had a chronological exposure history...so if he did develop a issue when he retired he had proof of the exposures.
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Old 21 December 2016, 09:37
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Originally Posted by Gumby2/6 View Post
Was just listening to a former 18D talk about the blast guages on NPR yesterday morning. He was relating a story of a deployed soldier being diagnosed w/ a concussion after having fired a "rocket" of some kind(they didn't get into detail about the specific type of weapon) from inside an enclosed area. interesting stuff.
That was a former co-worker.
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Old 21 December 2016, 10:10
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I too am a little hesitant about disregarding the initial findings/data and recognize the concerns that y'all and others have about possible correlation with plausible negative long-term financial impact.

24/7, do you know if the gauges are available outside of DoD? And do you know if testing/trials have been done with civilian tactical personnel?

I may reach out to the developer (I believe the former 18D y'all are referring to) and see if we can coordinate continued research with major SWAT teams. I fully understand that the exposure levels and frequency are not fully representative of military personnel, but it would be better than totally sidelining the program. May even wind-up offering some interesting data at those lower exposure levels/frequencies that would be publicly consumable.
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Old 21 December 2016, 10:19
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Yes, they are being worn by LEO / SWAT types. If you want a introduction to the 18D being interviewed let me know, easy day.
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Old 21 December 2016, 10:27
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concerns that y'all and others have about possible correlation with plausible negative long-term financial impact.

data at those lower exposure levels/frequencies that would be publicly consumable.
In my humble opinion, there are two issues.

Injury thresholds and mechanism of injury.

Re MOI: a buttload of research can generally say what it's not but there is no real agreement on what causes a mTBI, got to nail that down before a mitigation strategy can be adopted.
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Old 21 December 2016, 12:36
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I heard the story yesterday on National Politburo Radio about the Pentagon ceasing the use of BGs. Too shortsighted in my opinion. The science and understanding of TBI has come a long was in a short time, but we still don't know shit about the subject. The pressures generated from firing ordnance can be significant, and confounding results can be found with relation to where the weapon was discharged (open area, vs confined spaces, etc.).

We are in the infancy stage of learning about chronic traumatic encephalopathy, and have no data on long term implications for cognitive function, or whether the brain has some ability to heal or possibly make new neuron connections when some are damaged. We also do not understand why one individual may get concussed from much less overpressure, while another may be able to encounter the same relative force, yet stay intact.


It is the cynical side of me talking that says, hmmm Pentagon says "these blast gauges do not accurately predict TBI" while this may be true, it provides at least SOME data with which to form conclusions. Or is it the cost of thousands of cases of CTE that they are afraid of? Or opening Pandora's wallet (box)?

Last edited by 57Medic; 21 December 2016 at 12:38. Reason: spelling
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Old 21 December 2016, 22:05
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Yes, they are being worn by LEO / SWAT types. If you want a introduction to the 18D being interviewed let me know, easy day.
Awesome. Thanks. I'll circle back around and follow-up with you on this in January when my schedule is a little cleaner.
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