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Three physicians on the Mediterranean Island of Malta are calling or the use of boat propeller guards. Their paper in the Malta Medical Journal covers the accident and recovery of a propeller accident victim there.

The 44 year old man was scuba diving off Malta. As he was surfacing, strong currents pushed him into the propeller of the boat he dove from. The propeller was turning, but not at maximum speed. His friends got him back on the boat, and they sped back toward shore. Luckily, one of the dive team members was a cardiac surgeon who sprang into action administering first aid, and covering the victim’s chest wound with a towel.

The report addresses propeller accident statistics in the U.S. and Canada, since no similar statics exists for boat prop accidents in Malta.

Much of the article focuses on medical procedures used to address the victim’s very serious chest wounds (one of his lungs is wide open in the photos).

Case Report: Chest Wall Reconstruction Following a Speedboat Propeller Injury.
D. Sladen, A. Chasha, and A. Manche.
Malta Medical Journal.
Vol.26. No.2. (2014). Read More→

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Introduction

The boating industry often cites the dangers of being struck by a propeller guard as a reason for not using them. They claim boat propeller guards exhibit a much larger cross sectional area than an unguarded propeller and as a result those in the water are much more likely to be struck by the prop guard than struck by the propeller. The industry also claims blunt trauma injuries from being struck by a propeller guard are more significant than the “clean cuts” resulting from being struck by an open propeller.

What is Blunt Trauma?

Many of us hear or use the term, blunt trauma, without really understanding what it means. We grow up hearing about people being hit by blunt objects and suffering blunt trauma, but just exactly what blunt trauma is remains a bit nebulous.

When the human body is struck by a blunt object that does not penetrate the body, the body must absorb the blow. That energy can be absorbed by:

  • Partially crushing or crushing part of the body (hitting your thumb with a hammer)
  • Accelerating the body or part of the body (Force = Mass X Acceleration)
  • Secondary impacts (the body crashes into other things after being hit by the blunt object)
  • Drag (such as when the body is struck and moves through water)

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This post is Part 2. Please view Part 1 first.

Biomechanics

Per Biomechanics of Chest and Abdomen Impact. Chapter 53. David Viano and Albert King. Biomedical Engineering Fundamentals:

“The biomechanical response of the body has three components: (1) inertial resistance by acceleration of body masses, (2) elastic resistance by compression of stiff structures and tissues, (3) viscous resistance by rate-dependent properties of tissues.”

At moderate impact speeds, your body just deforms some to accept the impact OR it deforms enough to buy time until the affected segments of your body begin to move to absorb the load.

At higher impact speeds the ability of the body to deform is limited by its inertial and viscous properties. It can’t deform if it can’t get some of the internal fluids and tissues out of the way fast enough. You can be severely injured before your body can get out of the way.

The ability of an organ to absorb impact energy without failing is called tolerance.

Our bodies are well suited to try to protect our most valuable organs. For example: our brain is surrounded by our skull, our heart, lungs, liver, and kidneys are protected by our backbone and ribcage. Our extremities (arms, hands, legs, feet) are less protected, but more expendable. We can still survive if they are crushed (and we quickly receive the level of trauma care available at many major hospitals). One of my uncle’s had his arm crushed between a dump truck bed and its undercarriage a few years ago. Even though he was trapped for several hours before anyone became aware of his predicament, his arm was saved and he has since been been able to recover much of his previous capabilities. If his chest or head been similarly smashed, he would probably no longer be with us.

Vian and King note chest impacts compress the ribcage causing a tensile strain on the outside of the ribs. As compression increases, so does the risk of rib fractures. They also note that blunt impact of our upper abdomen (just below our rib cage) can compress and injure our liver or spleen before our body begins to accelerate from the force.

Common techniques to minimize blunt trauma injuries are to:

  • Avoid the impact
  • Reduce the impact velocity of the object
  • Reduce the mass of the object
  • Spread the impact energy over the strongest body structures
  • Wear protective equipment or pads
  • Extend the time allowed for deceleration (reduce peak acceleration of your body)

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Helimed life flight helicopter arrives

Helimed life flight helicopter arrives

We frequently read of people making great efforts and sometimes even risking their own lives to save the lives of boat propeller accident victims. A recent propeller accident re-enactment spurred us into action to recognize the pilots, EMT’s, paramedics, doctors, nurses, bystanders, and others that often come to the rescue. They often represent the difference between life and death for propeller strike victims.

Having read thousands of media reports of boat propeller accident victims, several common rescuer themes come to mind. Among them are the many people springing into action to try to save the lives of the victims by getting them out of danger, trying to stabilize them, transporting them to major medical care facilities, and tending to their wounds. While we do not have space of time to list the thousands of individual selfless efforts to try save those struck by boat propellers, we thought we would try to start to list them by category, then briefly describe one such instance as representative of similar efforts made by many others.

The Rescuers

  • Placing their body between loved ones and an oncoming boat to shield them from the propeller
  • Bystanders quickly calling authorities to report the accident
  • Stopping an unmanned circling boat that might repeatedly strike them
  • Well prepared and trained commercial vessel crews with adequate medical supplies on board tour, dive, snorkel, charter, party vessels
  • Bystanders that pull propeller strike victims from the water
  • Apply tourniquets or pressure to stem blood loss shortly after individuals are pulled from the water
  • On water rescue crews (USCG, RNLI, local water rescue crews, police & fire departments, etc.) including Search and Rescue
  • Getting air to victims entrapped on propellers
  • Removing the propeller when people are entrapped
  • Pulling them from the water
  • Doctors, nurses, and medics along with the group or nearby spring to action
  • Lifeguards
  • Marinas
  • 911 Operators & Dispatchers
  • Local paramedics and EMT’s that respond before life flight services arrives
  • Life flight pilots and crews
  • Surgeons and those who assist them
  • Blood Banks
  • Blood Donors
  • All These Groups Working Together to Save Lives

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