Tuesday, June 30, 2020

The Emerson 3PV Ventilator (Circa 1964)

Gather round the ol' manually cranked  hospital critical care bed all ye Whippersnapperns and take a quick little quiz on the history of air becoming breath. What do you get when you combine a Westinghouse hot plate, an ordinary natural gas meter, a couple of AC delco automotive switches, a trombone slide, copper mesh and a V belt from a 1960 Chevrolet Brookwood? House them all together with an air pump in a Maytag washing machine cabinet and you have a pioneering ventilator known as the Emerson 3PV.
The control panel of the Emerson 3PV ventilator shows it's
Maytag roots. Does that black knob control the rinse cycle or tidal volume?
Although a high school dropout, Jack Emerson was an innovative young man. His 2 brothers were physicians and Jack being an inquisitive young man, asked them what they needed in their medical practice. At age 22, Jack bought a rudimentary machine shop at an estate sale and began manufacturing medical equipment. His first device was an automatic agitator for laboratory use.

The idea for a cost effective ventilator came to light when he heard one of the leading trauma experts of the day, R. Adams Cowley, complaining about the high cost and availability of Engstrom ventilators which were the standard of the day. Dr. Cowley received  a $100,000 dollar grant to research shock following trauma and had to spend most of it on expensive Engstrom ventilators. A cost effective ventilator would free up grant money for other vital research.

After some tinkering in his Cambridge, Massachusetts machine shop, the ever enterprising Emerson cobbled together a ventilator created from a hodge podge of ordinary and readily available household and automotive parts. His unique creation was the first ventilator marketed with a humidifier thanks to the hot plate and a water vessel.

 Modern ventilators have filters to prevent contamination, but Emerson's 3PV went a step further. He incorporated copper mesh in the return tubing. Copper has antimicrobial properties and actually kills bacteria and viruses by degrading the cell membrane or protein coat of the virus.

One thing missing from Emerson's pioneering ventilator was an electronic monitoring screen made by extracting toxic elements from the earth via a process that is probably slowly killing us. Old school practitioners were satisfied with watching the rise and fall of the chest and auscultating breath sounds to verify ventilatory function.

Simple devices like Emerson ventilators have an inherent beauty. One way or another we could all wind up flat on our backs with a ventilator chugging away in the background. While we are thinking, "Is this all there is?" an image of the ventilator blowing air into our wounded meatsacks appears in our peripheral vision. I know my emotional bandwidth will feel like it's been hit by a grenade if I see a computerized microprocessor controlled gizmo keeping me alive. Find one of those old Emerson's in the basement somewhere and I'll be smiling even with that endotracheal tube jammed down my old, foolish craw.

Thursday, June 4, 2020

Don't Crash That Gurney

It's all fun and games when pushing an old Gurney in a straight line.
Objects moving through space at high speed with a sense of urgency are prone to mishaps. No, I'm not talking about the space shuttle Challenger. I'm thinking of  old school hospital Gurneys which were also known as prams, trolleys, or carts. These unwieldy conveyances had tiny wheels which were really more like casters. Each wheel had an independent locking mechanism that was activated by stomping on a tiny lever.

Adding the weight of a patient to the cart  resulted in a very high center of gravity that conferred an inherent lack of stability. Vintage Gurneys had no counterweights in their base like the meticulously engineered transport devices present in today's hospital. Tiny wheels, poor brakes and a high center of gravity were the recipe for disaster.

Pushing an old fashioned Gurney in a straight line at low speed was a walk in the park. Speed, uneven terrain, sharp corners or heavy loads were complicating issues and relevant factors in Gurney crashes

Crack ups while rounding corners with a loaded hospital trolley had some of the same elements as motorcycle wrecks. I've had personal experience with both types of mishaps. High side motorcycle and Gurney crashes are among the most catastrophic because the patient I mean, rider is thrown off the vehicle ahead of the line of travel of the vehicle and risks not only the fall but the cart or bike then plowing into him. The cause of these crashes is suddenly regaining traction after sliding or skidding around a corner. In the hospital any type of liquid spilled on heavily waxed terrazzo floors is the most common hazard responsible for high side Gurney mishaps.

More benign crashes are of the low side variety where the bike or   Gurney simply skids around a corner and the conveyance  slides sideways gently spilling the patient. Thankfully, this is probably the most common type of Gurney crash and results in minimal injury because the driver is often able to contain the patient before he impacts the floor. Collateral damage from broken glass IV bottles is a common complication of low side wrecks. The Gurney driver is usually in an emotional hyper response  state with marked frontal lobe detachment  after one of these mishaps and hastily picking up glass shards can result in colorful displays. Please, don't ask me how I know about this one but the scars on my fingers are probably a dead give away.

Another factor in gurney wrecks is overloading or raising the center of gravity by personnel standing on the cart for procedures like joint reductions.https://regionstraumapro.com/page/3.  This graphic illustration of an intrepid emergency medicine physician is a good example of a high flying reduction. Hopefully the good doctor  returned safely to terra firma when the procedure was completed.

CPR perfomed on a rapidly moving Gurney always reminded me of a rodeo where a sudden fall is awaiting  the rider.  The nurse performing compressions (somehow it was always a nurse in the saddle) straddled the patient while maintaining the exquisite balance of a Brahama  bull rider as the Gurney surged forward toward more definitive care. Once again the center of mass is raised and the urgency of the situation always manages to exacerbate the propensity for a mishap. The nurse furiously doing chest compressions above the patient was the canary in the coal mine since she was likely to take a tumble before the patient fell. Caution usually prevailed when the Gurney driver sensed the CPR provider was about to take a tumble and slowed everything down befor a crash ensued.

Just like Gundam mech robots patrolling an infinite universe,Gurneys were just about everywhere in the hospital orbit. Gurneys always held a warm spot in my heart because I saw them as a symbol of unification and, oh boy,  we could sure  use some of that in these difficult times.. We are all going to take that last Gurney ride someday no matter what event terminates our earthly existence. Pay close attention to the next soul you see on a Gurney because they can show us all how to take that final ride with a dignified sense of peace. All bets are off if an OFRN like me crashes the cart.