Necessity Is the Mother Of Invention

A need or problem encourages creative efforts to meet the need or solve the problem.” This saying appears in the dialogue Republic by the ancient Greek philosopher Plato and it has held true through the ages.

All through the ages, because of necessity, things were invented. For example, our ancestors wore only tunics and needed a place to put their belongings, so someone invented pockets. Another person saw wasted space in closets when clothes were hung on pegs or placed on shelves. The result is the clothes hanger. Until the 19th century, seeing-eye boys assisted blind people. Out of necessity, someone decided to train dogs to do the same task.

EMS is no different. Since man first started transporting the injured and ill to hospitals, inventions have involved to make the task easier. Instead of carrying an injured or ill person on a litter, a stretcher with wheels was invented that made the chore of moving the patient from place to place easier.

That brings us to Captain Manny Chavez, a paramedic/firefighter with the Houston Fire Department for 18 years, who has created an invention out of necessity. During Chavez’s career, he has worked two of the city’s busiest medic units (9s and 31s). These two medic units cover mostly the inner-city where the majority of people use 911 as their entry into the health care system. Most of the people in these areas are poor and generally do not seek medical care immediately. They wait, and the end result is that they get sicker and sicker. Then they call 911.

To make matters worse, many of the patients are obese. Much has been written lately about how Americans are becoming “super-sized.” Figures from the U.S. Centers for Disease Control and Prevention (CDC) show that 64% of U.S. adults are overweight and nearly a third are obese, or roughly 100 pounds overweight. Hospitals must buy extra-large medical equipment such as blood pressure cuffs and beds just to accommodate obese patients.

And as Murphy’s Law would have it, the “EMS Rule of Threes” applies – such patients are always on the third floor, it is 3 A.M. and they weigh over 300 pounds. Of course, there is no elevator. And, as Chavez says, “they are always in the back bedroom.”

Chavez faced many of these situations and found it impractical to try to carry an obese patient down two or three flights of stairs on a stretcher. Sometimes, he would try to strap a patient to a backboard. This also proved fruitless as the patient would eventually slide down the backboard and the medic on the bottom of the backboard always bore the brunt of the weight problem.

Chavez conjectured that there had to be a better way of taking obese patients down from the upper floors without injuring the medics or the patient. One of the methods he tried was putting the patient in a sheet or blanket. Unfortunately, the blanket or sheet would eventually rip. Next, Chavez tried putting patients into salvage covers that he could get off an engine company. This did not work, since the salvage covers were usually filthy.

Chavez and his partner, Mark Becknal, agreed they had to come up with something better. They tried using a mattress carrier. That failed. Next, they tried using a PVC fabric, similar to those found on the back of an 18-wheel truck that is carrying a heavy load. This too did not work.

Then one day, while sitting in a Taco Bell, inspiration struck Chavez and Becknal. They could not help but notice that a taco shell, although thin, held all the ingredients in place without ripping. Chavez and Becknal are not engineers, but they concluded there must be some physics behind the taco shell. They concluded that they needed an oval carrier that would bring the mass to the center while distributing the weight.

They fashioned their first device with PVC vinyl and seatbelt webbing and put 10 handles on it so the weight of the person could be distributed to a maximum of 10 people. The device was also designed so that patient’s head and face stuck out and was exposed for patient care purposes. It was designed to be carried at an arm’s length and would be approximately eight to 10 inches off the floor when carried, thus medics would not strain while lifting the device. They decided to call their new found invention the ManSAC (SAC stands for Single Axis Carrier).

The first time the ManSAC was used, it carried a patient who weighed 750 pounds. As Chavez described, “It was unbelievably light since the weight of the patient was distributed to the 10 people who were carrying the patient.”

The ManSAC is designed to carry up to 1,600 pounds, but has been subjected to a battery of independent testing from an engineering firm and has sustained up to 3,000 pounds. It is effective for removing heavy patients, rapid extrication, and the moving of patients down stairs and around corners. A patient who is transported in the ManSAC can be moved in the supine or sitting position. The ManSAC can also be used in conjunction with a backboard, which has been proven valuable during cardiac arrest sequences and with patients needing spinal immobilization. It is currently being used by several fire departments as part of rapid intervention teams. The ManSAC is also impervious to body fluids and chemicals and can be cleaned and reused in most cases.

As word of the new device and its capability spread, Chavez, working on a shoestring budget, went to the library and found out how to do a patent search. He did the search personally and after most of the legwork was done, he hired a lawyer to file the paperwork. Becknal became the salesman while Chavez oversaw the operation. They decided to trying marketing the ManSAC at a couple of fire conferences and suddenly the orders started rolling in. In fact, there were more orders than they expected.

The “production line” for the ManSAC became Chavez’s mother-in-law – Chavez bought a sewing machine and his mother-in-law went to work producing the ManSACs. As orders increased, another woman was brought on to the production line. Today, the ManSAC can be found in Dallas, Austin, Baltimore, San Antonio, Memphis and Chicago, as well as other cities.

Necessity is the mother of invention. Chavez and Becknal certainly proved this with their invention of the ManSAC. If you ever see a ManSAC in use or if your department starts carrying it, know that the taco shell was the idea behind it and with some ingenuity and perspiration, progress can be made.

For more information, go to or call 713-691-5815.

Gary Ludwig, MS, EMT-P, a Firehouse® contributing editor, is the chief of Special Operations for Jefferson County, MO. He retired in 2001 as the chief paramedic for the St. Louis Fire Department after serving the City of St. Louis for 25 years. He is also vice chairman of the EMS Section of the International Association of Fire Chiefs (IAFC). He is a frequent speaker at EMS and fire conferences nationally and internationally, and is on the faculty of three colleges. Ludwig has a master’s degree in management and business and a bachelor’s degree in business administration, and is a licensed paramedic. He also operates The Ludwig Group, a professional consulting firm. He can be reached at 636 789-5660 or via