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The nuances of ligature resistance

April 18, 2013
by Laurence D. Kopp, PhD
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Lesson: It takes a lot more than “ligature resistant” products to create safer patient environments

Nearly 30 years ago, a hospital engineer asked me to design and manufacture “releasing” or “break-away” closet bars. We made ligature-resistant flanges, each equipped with two flexible nylon pegs so that the bar, resting on the pegs, would be pulled down through the pegs when a downward force (in excess of a specified limit) was applied.

Being young and foolish at the time, I immediately applied for a patent in hopes of becoming an instant millionaire. There was just one problem: When the prototype was demonstrated to the nurse in charge of the floor, she exclaimed, “When the bar comes out, they will kill us with it.”  Here, I learned Rule 1: Nothing can be removable.

A maintenance man from the same hospital saw a closet bar in a recreational vehicle which he thought offered promise as a ligature-resistant shape. The hospital’s engineer asked us to make it and it became one of our closet bars. When this closet bar is installed properly, this bar should not be removable. Good, right? 

But then, there is another issue: What are the number and types of coat hangers that will be hung on that bar? What is the pull-out or breaking load for each hanger—or a group of hangers? Is it possible for a patient to bunch the hangers together, tie a ligature around the aggregated bunch, and gain enough support to attempt a hanging? Given the possible combinations, this is a very difficult question to answer definitively.

And, there are more than closet bars to consider in a patient room. Window, privacy, and shower curtains—along with their means of suspension (curtain rods, ceiling tracks, etc.) present a similar range of questions and challenges given the range of potentially lethal combinations.

If ligature resistant products are to be non-removable, tamper-proof fasteners are imperative. But which ones should be used?  I can only answer this in the negative:  Don’t use snake-eye or spanner head fasteners. A patient can break off the “tongue” of a zipper and obtain a good removal tool having two prongs that fit into the two holes in the head of the fastener. Don’t use Allen head fasteners because they are so common: the wrenches for them can be purchased in any hardware store and can be smuggled in by friends. Instead, investigate the wide range of tamper-resistant fasteners manufactured around the country. 

There are degrees of ligature resistance. Take grab bars for example: Plates have been welded on standard grab bars to fill the space between the grip and the wall. Assuming no gaps exist, ligature resistance is accomplished, or isn’t it?  A patient could tie over the whole grab bar left to right.  Therefore, sloping flanges are needed to let the tie slip off when a downward force is applied.

Dispensers, such as those for paper towels, have openings which are potential points for ligature attachment. A patient could possibly use a utensil, modified to fit through a slot or opening, but then pivoted to prevent removal and accept a ligature tie.  In this case, a recessed shelf is a far safer choice.

While mirror frames can be helpful in improving durability and mirrors generally lay flat against the wall, these too may present a possible hazard.  The concern is that a sheet could be jammed behind the top edge of the mirror frame such that it could support a patient’s weight.  This possibility led to the creation of another product—a mirror guard to help prevent this possibility.

In the last five years or so, facility designers have sought ways to retrofit wall-hung lavatories (sinks). Hoping to meet this need, we spent two years developing a retrofit faucet.  However, when our prototype was installed on typical wall-hung lavatory (an American Standard Lucerne lavatory), several points of ligature were discovered: 

(1) Our prototype faucet was ligature-resistant from the front but if a patient placed his/her head on either side of the lavatory and against the wall, we found that it was possible for a tie to be made and used.

(2) Like many lavatories, this model includes an overflow hole that allows excess water to drain without spilling on the floor. However, we found that this hole offers a point of ligature.

 (3) The grid drain at the bottom of the basin has a pattern of relatively large holes that allow for continuous drainage from the sink. However, these holes present potential points of ligature as well.  

(4) A wall hung lavatory like this one can accept a ligature tie horizontally, left to right across the top surface that butts into the wall. (With any lavatory unit, exposed water supply or draining piping may also present ligature attachment concerns.)

After considerable research and development aimed at satisfying the lavatory retrofit market, we couldn’t develop a retrofit option that we really liked. Instead, we turned our attention to developing faucet/lavatory/cabinet combinations that would eliminate identified problems and replace conventional wall-hung lavatories altogether.

To effectively maintain the highest level of patient safety, a behavioral health facility must utilize a complete blend of thoughtful design and construction, together with product selection and installation practices, to create a thoroughly ligature-resistant environment. Let me offer two examples: