The Elusive Dry Weight: A Dialyzor’s Lessons Learned
The elusive dry weight: that magical number that controls every treatment. Take off too much and you can have the dreaded cramps, blood pressure crashes, and worse. Take off too little and leave with that heavy, bloated feeling, puffy ankles, and wheezing. The bottom line is that the kidneys control water in your body and how your body gets rid of it. If they are not working properly, your body is going to have water buildup somewhere and everyone retains water differently: belly, ankles, fingers, and lungs, to name a few.
It is very distressing to see people starting dialysis who simply accept that it is OK to experience blood pressure crashes, cramping, fainting, and take hours or even days to recover from a treatment due to fluid removal. Treating these episodes with pickles, pickle juice, mustard, broth, tonic water, saline, and water, etc…are stopgap measures, but should never be acceptable, ongoing techniques to regulate what is, essentially, your lifeline. Here is what some other dialyzers have said about water:
“I am new to dialysis, today was only my 8th session. What I'd like to know about is blood pressure dropping. I never had a problem with this until I began dialysis, in fact I have high blood pressure. The past 2 or 3 times I've had dialysis, I've come home and about 30 minutes to an hour later my blood pressure drops drastically. Everything goes dark like I am going to pass out and my hands and face go numb. It lasts for a few minutes and then my bp will go back up.”
“My nurse said they are still trying to find my dry weight. I am new to all of the dialysis terms, so I don't know what profile means or the numbers for it. How do I know when I am at my dry weight? I only gain between 1-2 pounds in between dialysis days (M/W/F) and lose between 2 & 3 pounds after treatment.”
“It really freaked me out with my vision constantly going dark at first.”
“Also new to dialysis. Came home the other day and next thing I know I'm waking up laying on the floor. Very scary. Told I need to drink more after dialysis.”
“…started out on two BP Meds, then down to one...then they told him not to take it on the days he did dialysis. Now, 6 months in, he doesn't take any BP Meds. His BP was good during treatment, he had some issues with it being really low right after they unhooked him. They had him drink broth...or pickle juice, turned out he was dehydrated. It's a delicate balance act....”
“My BP drops too after dialysis…one trick that helps me is a kick of sodium… i like pickles so my dietician approved me to have a Vlasic low sodium pickle spear when my BP drops at home..”
I have always wondered at the insanity of removing excess water to the point where a bolus of saline is required, or you are told to drink salty broth or pickle juice. Removing too much water also causes your body to crave fluids to replace what was removed, which creating an insatiable thirst that, in turn makes you drink more, and increases your blood water volume, creating a never-ending spiral of destruction.
If you only gain 1-2 kilos between treatments, why do they insist on removing 2-4 kilos, especially if there are no obvious signs of fluid overload—only to end up adding saline when the body “crashes”. Kind of defeats the purpose, doesn’t it?
I found it very disturbing to read this Q and A exchange between dialysis nurses that I found by accident on a nursing website:
“I am fairly new to dialysis (9 months now), but at our clinic, as well as in our acutes department, we are never to turn the UF completely off. The minimum we can go is 300 ml/hr. and if that is not sufficient to stop the cramping or hypotension we give fluid back. It would take someone with more experience than me to give you the rationale behind that policy, but at no time do we ever completely turn off the UF, even if we are not to remove any fluid. We simply set the UF rate to 300 and return whatever we remove.”
NOTE: This is one that I find particularly disturbing, in that they just return whatever fluid they remove! An exercise in futility?
“Even though I'm a new nurse let alone new to dialysis, my manager, charge nurse, and fellow staff RNs have all stressed turning off the UF when the patient is in distress, whether it be cramping or low BPs. Why continue stressing the body and heart on pulling more fluid if the BP is too low or the HR is too high?
NOTE: finally, the first voice of reason in over 2 pages of comments!
If the nurses entrusted with our care do not understand the concepts of water balance and how the machines work, how can we possibly feel safe? We need to learn! It is critical, for us, the dialyzors, to learn the nuances of our bodies, and how, when and where water affects us, so our water removal is done at a rate that does not cause problems.
When you start dialysis, balancing water buildup is the most critical and, perhaps, even life-threatening issue you will encounter. According to the U.S. Renal Data System (USRDS), cardiovascular disease and stroke are the most prevalent causes of death in dialysis patients, and have been linked to fluid overload. Too much or too little water removal can lead to heart complications, and even death.
Dr. John Agar describes water removal as a “waterfall” effect. Dialysis removes toxins and water from the blood. Once water is removed from the blood, a chain reaction, or waterfall, starts. Water from inside cells shifts to the “interstitial” fluid around the cells, and this water in turn, shifts into the bloodstream. This waterfall, or water moving from inside cells to between cells to blood, takes time. If you take water out of the blood too fast, as many in-center dialysis treatments do, your body cannot keep up, which starves your organs and tissues of oxygen-carrying blood, causing cramping, blood pressures crashes (“stunning”), vomiting, and even passing out.
Ultimately, if you keep this type of treatment up, you will damage your heart and organs. (Your gut is not immune, either. A side effect of removing too much water is stunning the gut, which releases toxins into the bloodstream that can trigger inflammation and even sepsis.)
Not removing enough water leads to fluid overload, which has another set of complications. One sign of retaining fluid on dialysis, besides edema (swelling) in the hands and feet, is rising blood pressure. The more water you retain, the harder your heart has to work, and the higher your blood pressure soars.
All of this brings me back to dry weight! HD treatments include a prescription for water removal (ultrafiltration, or UF) targeted to “dry weight:” the lowest weight a patient can tolerate without development of symptoms or hypotension (low blood pressure). Dry weight is used to calculate UF volume (amount of water taken off during treatment) and the UF rate, or UFR (how quickly water is removed) for each treatment.
In most cases, dry weight is found by trial and error, often by “challenging” the weight. This is when the nurse adds extra water removal. For example, if you gain 2 kilos between treatments, s/he may suggest taking off 2.5. If you don’t cramp or have blood pressure drops, s/he may assume your dry weight is lower. If you suffer from symptoms, then your dry weight may be on target, or even too high. Clinical assessment of dry weight is crude and often imprecise. The concept of ”challenging” dry weight, or raising the water removed until cramping occurs, seems downright barbaric to me.
A rule of thumb for UFR on a NxStage machine (the machine I am most familiar with. The protocol is similar with other machines) is to keep it less than 10 ml/kg/hr. It is known from more than one study that keeping UF rates at or below 10 ml/kg/hr reduces complications and improves survival. Any higher and your body can’t keep up: your blood pressure will drop, cramping will occur, and you may feel faint, or take hours to recover from your treatment. For those who retain large volumes of water between treatments, it is often impossible to remove it all at a rate of less than 10 ml/kg/hr in the usual 4 hours prescribed—so they raise the rate to remove it faster, which may result in cramping and crashing. If your UFR is less than 10 ml/kg/hr, intracellular water can refill your blood as fast as dialysis removes it. So, your blood volume won’t drop and your blood pressure will be stable. If your UFR is higher than 10 ml/kg/hr, your intracellular water can’t keep up with replacing the water lost from your blood. Your blood volume must fall and your blood pressure will drop, too. (You’ll feel awful.) The more your UFR exceeds 10 ml/kg/hr, the greater the gap between water loss and capillary (blood vessel) refill. The greater the gap, the higher the risk of affecting your blood pressure. The longer your treatment time and the lower your UFR, the lower your relative risk of stunning, cramping and damaging your organs.
One way YOU can take control of your fluid removal is to use the Ultrafiltration Rate Calculator on Home Dialysis Central. If you find that your UFR falls is in the red zone (greater than 10 ml/Kg/hr), then you know you will need to increase your time to safely remove all that water. This is not a problem if you are doing home therapy, but if you are in-center, it is going to require a change in your doctor’s order, and you may meet with resistance from the staff. If faced with the risk of removing too much water, too fast, and stunning your organs, cramping, and crashing, the alternative is to remove less water until you can get your doctor on board with giving you longer treatment times—or reduce your fluid gains.
At the end of the day, YOU are in charge – you own your treatment. It is your right, and your responsibility, to understand all you can about your treatment: the rate of blood flow, the amount of water removed, your UFR, and your labs (all of them, not just the sugar-coated results they give you with smiley faces).
The obvious solution is that the more water you need to remove, the longer your treatment needs to be. Removing fluid slowly, over time, allows your body to balance itself during this process. Have you ever seen the Panama Canal? The ship cannot progress until the lock is completely full, then it passes to the next lock, where it is lifted up, and then to the next lock. Each lock is balanced before the ship can move on. This is how good dialysis should work, and it can best be achieved with home therapies, where you are not limited by the constraints of in-center scheduling and time limits.
Which brings me to my conclusions about dry weight. For dialysis to work for you, you must understand what it does, how it works, and take responsibility for each and every treatment. Don’t just sit in your chair and let someone who may, or may not, understand the complexities of UF, and how it relates to your body leave you cramping, crashing or collapsing post treatment. While pickle juice, mustard, Gatorade and broth are all remedies for that occasional treatment gone wrong, accepting them as an ongoing solution is not OK.
Sources:
1. Hemodialysis: Diffusion and Ultrafiltration, Journal of Nephrology and Hypertension, http://austinpublishinggroup.com/nephrology/fulltext/ajnh-v1-id1010.php
2. Controlling Volume in Hemodialysis, Renal and Urology News, http://www.renalandurologynews.com/expert-reviews/controlling-volume-in-hemodialysis/article/58097/
3. Home Dialysis Central: http://www.homedialysis.org/life-at-home/articles/your-heart-on-dialysis; http://www.homedialysis.org/life-at-home/articles/fluid-and-solute-removal-part-one; http://www.homedialysis.org/life-at-home/articles/fluid-and-solute-removal-part-two;
5. Danger inherent in high dialysis ultrafiltration rates, http://www.farces.com/danger-inherent-in-high-dialysis-ultrafiltration-rates/
6. Rapid fluid removal during dialysis is associated with cardiovascular morbidity and mortality, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3091945/
7. http://allnurses.com/dialysis-renal-urology/is-turning-the-907117-page2.html
Comments
stephanie young
Dec 04, 2023 7:19 PM
Ed Adams
Aug 31, 2023 10:11 PM
Dori Schatell
Dec 04, 2023 8:06 PM
For some reason I didn't get notifications of the comments in this blog post, so am just now seeing yours. How are things going for you?
Joshua
Aug 01, 2020 4:29 PM
1. UF means "water removal."
2. EDW means estimated dry weight. This is a moving target based on your previous post-treatment weight trends (initially a guess by your MD placing the order), a conversation with your nurse where you discuss appetite over the interdialytic period, constipation, diarrhea, how you felt after your last dialysis.
2a. If you aren't having this conversation you're doing yourself a disservice. You might have a rookie nurse who hasn't incorporated more than basic principles into their PRACTICE (there's a reason they call the work healthcare professionals do a "practice;" it takes time to do it well). If my pt tells me they've been experiencing constipation for 48 hours and they've been eating more than usual, I might look at a 4kg interdialytic weight gain differently than I do for the same gain on a person who tells me they have had regular BMs and poor intake over the same period. The former may have a UF goal of 3kg that day and the later 4.5kg (weight limiting).
3. 10mL/kg/hr should be your target as this is cardiac safety threshold. More UF than this will cause cardiac stunning and accumulate over time. 10mL x 100kg x 4hrs= 4,000 mL UFGoal.
4. Sometimes nephorologists are poorly communicating their orders to you and may be telling the nurse to challenge your EDW (or take more off and try to lower your EDW). They do this because your BP is critically high, you have unresolved edema, and several other reasons. They don't see you at the ends of your treatments, so they don't see the cramps they cause. If you're ESL, sadly the results can be worse regarding the patient-MD communication. Learn to advocate for yourself and ALWAYS ask the nephrologist when they are leaving your chairside OR you are leaving an office visit, "what are you planning to tell the nurse to change about my orders today?" This can help you stop something before it happens.
5. The experienced nurse's brutally honest take: 90%+ of dialysis patients take none to minimal ownership of their care and rarely participate even when given repeated opportunities. This is universal across all race, creed, and socioeconomic backgrounds. This can lead to SOME healthcare professionals becoming a little jaded about effective communication between their decision making process and your ears! Ask questions and participate in your care!
6. Losing your kidneys, starting hemodialysis, and the resulting sequelae that come with this will inevitably lead to cardiovascular disease progression (your heart and blood vessels will get weaker, more plaque, more scar tissue, more disease). The day you start dialysis you may be able to pull off 5L in a treatment and go back to work after that. 3 years into it, depending on your disease process and how well YOU have been managing it, you may find 3L in a treatment is all your body can handle.
7. Try to have consistency in your dietary intake, bowel movements, fluid intake, and wear similar clothing to dialysis when you get on the scale to get your pre-treatment weight. This way you can identify things that may indicate you need more or less UF today than the simple math of Pre-weight minus EDW indicates for your UFGoal that day.
8. Do HOME dialysis. More frequent days, less time per treatment, less high levels of toxins building up between treatments in your body. This leads to a MUCH better health outcome compared to incenter dialysis that is done 3 days/week. If you think you can't do home dialysis, I have trained a 92kg 91 y/o with dementia and his 61kg 87y/o wife to cannulate him. They did it successfully for 3 years until his death at almost 94!
9. Do not allow physicians to base your EDW adjustments off your BP, or other assessment data. Have a conversation. I have countless patients that have ridiculously poor control over their BPs (230/130 daily). When you challenge their EDWs they cramp and get symptomatic hypotension and "crash."
10. Any piece of assessment data, BP, pulse, lung sounds, leg edema, diet, appetite, bowel regularity, etc are just a PART of the equation to setting a goal for EDW.
11. When you're setting yours my general rule is TRY to stay within no more than 1.5kg over your EDW on your first tx of the week and no more than 1kg above your EDW on consecutive treatments that week. If you find you can meet your EDW your last treatment of the week without issues, maybe try to get within no more than 1kg above your EDW the first treatment of next week and stay closer throughout the week. The goal here is to have no difficulty breathing from excess fluid, no edema in your legs, no distention in your abdomen, and well-controlled BP. Fluid alone may not be causing alterations in those desired outcomes. Maybe you have a bypass and your left leg has edema no matter how much fluid you take off. Maybe you worked in a coal mine and have some inhalation injury in your lungs that causes fluid build up. Maybe you're one of the handful of patients that needs 4-6 BP meds at high doses to get control of it and you haven't yet figured out the medication regimen yet.
Have the WHOLE conversation
Dori Schatell
Dec 04, 2023 8:08 PM
Mary
Jun 11, 2020 5:46 PM
Brett
Jun 18, 2019 6:03 PM
Virginia Y. Morata
Mar 21, 2019 9:58 PM
Dick Parker
Nov 24, 2018 11:46 PM
John Agar
Jan 19, 2018 11:56 PM
The concept of weight in haemodialysis in particular, is fraught with poorly understood terms and confusion. As Anthony says (above), I, too, prefer target weight to dry weight as the better term.
The problem with clinically defining dry weight ... as you have correctly stated is the all-too-common but erroneous medico-nursing in-centre vision of dry weight ... as “the lowest weight a patient can tolerate without the development of symptoms or hypotension (low blood pressure” is EXACTLY due to the fact that the speed that tissue fluid (water, if you like) can move from cells —-> interstitial space —-> intravascular space —-> dialyser —-> drain is rate limited!
So, especially if the dialysis process is too fast, too brutal, and too aggressive, and plunders and rips fluid from the blood ‘compartment’ (the intravascular space) faster than fluid can then be drawn from the interstitial space to replenish the blood, and in turn, fluid can be drawn from the cells to restore the interstitial space ... the reverse waterfall concept ... then the blood compartment will rapidly become fluid-poor while the cells and interstitial tissues remain relatvely fluid-rich. As it is the blood volume that determines the blood pressure, hypotension during dialysis can be erroneously used to define “dry weight”
..... “Ha!” Says the nurse, “we must be at dry weight ‘cos the BP has crashed”
No ... the cells and interstitium can still be wet as wet, despite that the volume contraction and clinicL hypotension that has just occurred have incorre tly been interpreted as signalling “dry weight’!
Herein lies the conundrum of the all-too-often all too rapid, too brutal, and too aggressive dialysis regimens thT seek “dry weight” from an entirely incorrect premise,
I tried to explain this in many previous blogs on the dialysis waterfall, speed kills and understanding volume. I also blogged the different terminologies of dialysis weight at:
http://www.homedialysis.org/news-and-research/blog/201-A-Primer-on-Haemodialysis-%22Weight%22
Theodôr
Jan 19, 2018 6:41 AM
In my daily practice I try at least to see if a patient understands this dry weight concept. For many it seems to much to handle to overcome thirst. Our team foucusses on the "hidden salt" in foods and drinks ( alike hidden high phosphate in many "light drinks"). Once too much salt enters the body the struggle is bound to start. Avoiding that is good advice but not easy to achieve! Huge portions and cups are a US handicap on top of that! Together as a team, led by dietitians, but supported by nephrologist, nurses and Social workers like myself we educate to great length. But the patient has to be part of the team. Also powerful therfore are are peer group-oriented programs like "Making Peace with Fluids", a proven succes from S. Johnstone and her colleagues in Southern California. Many roads to achieve the minimal burden to remove fluids and/or dehydration!
Cheers,
Theodôr
Judy
Jan 18, 2018 10:04 PM
Anthony
Jan 18, 2018 9:39 PM
Yes, during 8 weeks training in clinic I regularly experienced the crashes attendant upon an over-ambitious UF goal.
At home, after taking my weight naked, pre-breakfast, post bowel movement, post a night of producing 600 ml of urine for many months I have established a "dry weight" of between 62.5 and 63.5, i.e. its not constant by any means. With an interdialytic weight gain ON AVERAGE of zero I'm fortunate to be able to set a UF goal of 200 mL, an amount replaced by re-infusion at the close of dialysis.
My actual dry weight? Who knows. I prefer the term "target weight" and have set mine at 63.0.
A nephrologist offered me a rule of thumb for dry weight: if your BP is around 140/80 or slightly less immediately after dialysis your weight at this BP is your dry weight. Fair enough.
Susan Ostrzycki
Jan 18, 2018 7:47 PM
Leong Seng Chen
Jan 18, 2018 9:20 PM