Monday, January 3, 2022

Roller Clamps Were Pioneers in IV Fluid Regulation


The past is like a foreign country where things are done differently, before the extravagant complexity of intravenous pumps and controllers, simple little roller clamps ruled the roost when it came to IV regulation. I was totally fascinated by these clever little gizmos and even had a collection of vintage roller clamps that I recently unearthed from my nursing archives basement junk hoard. 

These unsung heroes of the IV therapy universe deserve further study as they are not as simple as they appear. An injection molded cage with wheel guides molded into the sides to accept the axles of the adjustment wheel is the most obvious feature. When the wheel is positioned at the top of the housing an uncompromised flow of IV fluid ensues. The device must apply just the right amount of friction to the plastic tube to remain stationary while leaving the lumen of the IV tube wide open, not an easy task. The device then had to regulate the flow of IV fluid by changing the lumen of the IV tubing as the nurse turned the adjustment wheel.

There was strict dogma delineating the correct position of the clamp on the tubing.  Our rigid, uncompromising diploma school instructors insisted on having the roller clamp positioned about 2 inches below the drip chamber so as to be able to locate it in the dark. Old nurses never, ever flashed on blinding overhead room lights at night. Sleep was revered as a healing agent. Having the clamp just below the drip chamber made it easy to locate at night.

There were 2 methods of establishing a flow control region within the clamp housing and one entailed the wheel traveling along an inclined ramp molded into the bottom wall of the device. The other entailed a clamp with the base parallel to the open wheel access port, not a ramp in sight!  The wheel guides were inclined so the wheel traveled at an angle to the base of the clamp whereas the wheel was much closer to the bottom of the clamp when rolled down. The pressure on the IV tubing was varied by the up and down movement control wheel as it moved along the inclinations in the wheel guides.

Some really fancy roller clamps were dual action in that both a ramp and a variable inclinable control wheel changed the lumen of the IV tube. Some things in nursing made no sense and one of the most common places to find these over engineered, exquisite roller clamps was on clysis sets that were used to give fluids subcutaneously. Drip regulation on clysis sets was not a big deal, so why the fancy roller clamps?  Some mysteries are never solved, especially in nursing, but that's a topic for another day.

 Clysis sets were really old school and not subject to medical supply companies seeking to maximize profit margins by making cheaper roller clamps. Travenol clysis sets with dual action clamps even had metal axle spindles on the control wheels. I'm sure it would have been more cost effective to injection mold the wheel and axle in one piece. No cost was spared in producing these roller clamp gems.( For more foolishness on clysis: . )

One of the problems with roller clamps was a phenomenon called control point drift which occurred when the control wheel spontaneously moved to a region of less pressure increasing the lumen of the IV tube resulting in increased flow rate. Definitely not a good thing, especially when titrating vasopressors. The dual action clamps with metal control wheels were rock solid once adjusted. The increased  friction exerted by the metal spindles effectively attenuated control point drift.

Another problem with roller clamps involved the properties of the PVC intravenous tubing itself. After adjustment a phenomenon known as cold flow creep sometimes occurred. The lumen of the IV tube would decrease even though there was no movement of the control wheel. Lengthening the control zone on the clamp helped control this problem. Generally speaking, the longer the roller clamp the more stable the infusion rate. Short, stout roller clamps could be a real bear to regulate, some nurses even resorted to taping the control wheel in place.

The labor investment required by manual IV control was considerable because roller clamps needed frequent adjustment, but who would you like to see standing at your bedside, a concerned nurse or a noise barfing electronic poseur? Roller clamps also limited the number of IVs that could be managed on a ward. On a 30 bed unit the maximum number of  running IVs was abour six. Roller clamps are long gone, but not forgotten.


  1. The clamps remain on every set of IV tubing. They just remain open and are superseded by the pump. (True as of two years ago. I haven't checked since retirement.:)

    1. That's nice to hear since they were so functional and those over engineered electronic devices sometimes fail. There were so many different types of roller clamps that they made for nice collectibles. I just love to admire my old Travenol clysis set clamps that were dual action and had separate metal inserts for their trunions ( the little axles that ran in the grooved side walls.) I'm sure their manufacturing cost would make them unavailable in today's profit margin obsessed world.

    2. My grandfather, Ralph Gardiner, invented the roller clamp.

  2. I never thought much about them, but they were ingenious little devices, weren't they?

    1. Yep...It's the neat little things in life you appreciate at my age. Thinking about stuff like roller clamps provides me with a brief escape from my cognitive fun house!

  3. Hi "OldfoolRN",
    I am an "OldfoolMD" and I was really touched by your blog, it brought back a lot of memories. I trained from 1970 ~ 1979 and the hospital(s) were my home. I was from the "country", dirt poor but "mother" did take care of us. Duty every 3~4 days and long evenings spent in the library preparing for grand rounds was our life. Nurses were very nice and taught us the practicalities of the medical care theory we all learned in classrooms; all were very supportive except the OB department (for male physicians/residents) - "you were never going to have a baby and you have no idea how it feels/felt". We did not have to fear lawsuits, there was a lot of respect for doctors, nurses and the religious staff (many nurses were nuns). Some of our best teachers (MDs & RNs were former military having served in combat) and were very "practical".
    I appreciate the improvement in technology (having been injured in combat myself) but I miss the human element, this compassion and humanity that was bonding us, like I experienced in combat. Our administrative staff was minimal, medical records were filled after seeing the patient (not during rounds), many patients we knew by first name (University Hospitals served the underprivileged), our personal connection with our patient population helped us provide better care. No JACHO, employee unions, strikes were still far away. We never charged fellow staff members (any staff members nor any member of the clergy). Our bedside manners were based on Dr. Kildare, The Interns, Ben Casey MD (for the surgical geeks), and Marcus Welby MD for the later students. One thing our medical director (a former Marine officer) was adamant about, it was that we all stuck for one another, regardless of our position in the hospital pecking order, mutual respect was on the plan/order of the day; we were a family.
    May God bless you and on the behalf of all the medical students that you "gently" sponsored throughout their training, thank you. Ciao, L (MD, Veteran)

  4. Many thanks for the kind words OFMD. One of my favorite activities in the OR was reaching out to medical students. I remembered how foreign the OR was when I first started.

    It was a custom at our hospital to "repair" poorly functioning needle drivers by torquing the ringed handles in opposite directions rendering them unusable. I used to collect these instruments after the surgeon's "repair" and restore them by sandwiching them between 2 blocks of 2X4s. The 2 boards were then smashed together using a Volkswagen car jack and allowed to sit overnight.

    I would give the "refurbished" needle holders to medical students along with discarded suture for them to practice surgical skills. I was really adept with opening and closing needle holders without having my fingers inside the rings of the instrument and taught this magical trick to many students so they could delight their attendings.

    I was so lucky to have never worked in today's corporate driven medical corporate culture. I trained and worked at a pure charity hospital before retiring from the VA system.

    In our time, surgeons were the apex predators in the hospital world. I worked really to be a good scrub nurse and it really paid off. If a nursing supervisor like my all time nemesis, Alice, would give me the business, the surgeons would stick up for me. I remember Dr. Slambow telling her many times "We're busy here, Alice, go bother someone else." In today's world of entirely separate nursing and medical administrative silos, I don't think it would have been as effective. Hospitals seem like a parallel universe today with sparse remnants of old school custom.

    Thanks for taking the time to comment!

  5. Roller clamps are far from being dead. They still remain on every set and present a handy backup option in the case the pump would be too much hassle. Where I work the internal medicine departments usually make use of those devices saving the pumps available for the drugs requiring more precise control over the flow and to bother the patients with their innecessant bleeping of course.
    It's quite interesting to hear of the days gone, when nursing was more of the calling than a profession. Well, the nursing schools still thump their chests and proclaim that anyone who is planning on this career should have a calling. The idealist in me admires that spiel, although the cynic wanders whether the "calling" spiel is misused nowadays to sweep under the rug the issues of work hours and paychecks. That last one is one area where I am quite thankful for the progress the nursing made as a profession, with all respect to the auld lang syne.

    One of our instructors in the nursing school was roughly of the same age you are. We all admired her knowledge, her sharp wit, her eye for detail and her focus on what made nurse a good nurse. She, on the other hand, sometimes bitterly called herself a dinosaur, someone possessing lots of skills, unique nowadays, but those increasingly were left unused. It was made all more blatant that most of the year she had to teach virtually through the zoom (a videoconferencing software, ala skype), leaving her without a way to at least interact with the audience in a natural way. She did adapt fairly graciously to the new realities however, and she was one of our favorite teachers. However, she decided to retire from teaching undergraduate students after that year, and only worked with those doing the masters degree. I still consider myself to be very lucky that we learned from her. In the hospital I work now when I tell other nurses where I studied, people ask about her and remember her fondly (it's a small world and a small country -- I live in Israel). You remind me of her somewhat :) Have you ever considered teaching?

    Take care OFRN in these o-my-croned times.

    Yours truly, whispersnappeRN

  6. Thanks so much for your wonderful comment, Snark. I don't think I have the cognitive ability to teach much of anything and besides my knowledge of current medicine is pretty much obsolete.

    I really enjoy sharing with you bright youngsters what the olden days of nursing were like and of course who knows when you might need to insert a Foley with using only 2 finger cots ;-) Gloves were a rare commodity and only used in the OR when I was working.

    Health care in the land of the free and the home of the brave has done a really lackluster job in dealing with COVID. Preoccupation with profit margins is not compatible with public health. I suspect healthcare in Israel is much more comprehensive and advanced. When I notice that one of my many prescription drugs was manufactured in your country, I feel confident of the quality control.

    Thanks for taking the time to comment, you really brightened my day!

  7. I LOVE roller clamps! I've very much an anti-pump person, when at all possible. Most ER nurses use the AC for their IV site, which drives me insane. I'll go there in a pinch, but I much prefer a forearm or hand IV. Why? Patients can't bend their forearm and occlude the IV line. An AC IV plus a pump is a recipe for endless beeping irritation, both for the patient and the staff. I just go forearm site, IV bag with roller clamp, and on my merry way.

    Which also makes me miss the dial-a-flow device that most rural hospitals still have but big city fancy ones have done away with. Give me a forearm IV and liter of LR or simple antibiotic onto a dial-a-flow all day long. I love it.

  8. So great to hear from you shrtstormtrooper, I was thinking about you when reading about the COVID rates in Texas.

    Those little dial-a-flow gizmos were pretty cool, simplicity at it's very best. There was a similar doo dad called Versarate that was easier to read because the numbers were larger. There were problems with leaking dial-a-flows followed by a recall and then they disappeared for good in our area. The coolest part of these simple in line controllers was the absence of alarms, just set the rate and forget it.

  9. I think I caught an anachronism in a film I was watching. When did the PLASTIC IV roller clamp come into general use? What kind of flow rate control device was used before the plastic ones?? Thanks

  10. Plastic IV roller clamps have been around for all my time in nursing. I really get a kick out of things that have stayed around forever like mail boxes, fire hydrants, and plastic roller clamps. When my Mom was a nurse in the late 1930s IVs were cobbled together in house from bulk supplies like latex tubing and reusable glass liter bottles. Back in those days a small metal "C" clamp was used to control IV flow and worked fairly well with old latex tubing because it was so easy to compress and once compressed by the metal clip, it tended to remain at the same level of compression Plastic IV roller clamps still come with every set of IV tubing that I'm aware of-it's nice to have the continuity over the many years despite the fact most IVs of today are on pumps or controllers. Thanks so much for taking the time to comment on my foolishness which seems to get worse as I age!