A common scenario that occurs daily, heck even perhaps hourly, in most emergency departments or intensive care units around the world including providing patient with IV fluids rapidly via fluid bolus to resuscitate hypotensive patients or those who are in shock. In order to mitigate said hypotension/shock, the most common response by clinicians is to administer IV fluids. Which IV fluid is a matter that is up for debate. You can check out my post on the matter HERE. After the choice of IV fluid is made, the next decision is whether the patient will be fluid responsive or not. Methods to determine fluid responsiveness can be evaluated HERE. After that, how are our nursing friends going to administer the ordered fluids. Will it be via a pressure bag or via the IV pump and hitting 999cc/hr as the rate?
First reason why rate is important: Extravasation
This question has several components to answer properly. First, in several prior posts on this site, I have elaborated on how quickly patients extravasate the IV fluids we provide to them.
Lobo et al. found that “68% of the saline infused had escaped into the extravascular fluid compartment at 1 hr” when their team provided 1L of 0.9% NaCl over 1 hour to health volunteers. Take a second to think about this as it is important. This means that what stated in the blood vessels was ONLY 32%. ONLY 32%. The rest would be doing absolutely nothing to benefit our patients.
We now know what it is like in healthy volunteers. Let’s take it a step further and look for data in patients who are deemed critically ill. Here, Ragaller et al. cited a paper from 1998 that I cannot get my hands on and stated “Isotonic crystalloid solutions… their effect on plasma volume expansion of approximately 200 ml for every 1000 ml administered, with an intravascular half-life of 20 to 30 min, is very limited”.
My interpretation of these data is that if a critically ill patient is provided with 1L of IV fluids, 80% of this fluid is extravasated. 50% of the fluid infused is lost within 20 to 30 minutes and goes into the interstitial space. These data justify the rationale as to why nurses should not place a liter bag of fluids on the pump and hit 999ml/hr. These patients will need at least a pressure bag to provide an amount of fluids that would actually determine fluid responsiveness.
Vascular Leak Index (Updated on 05.05.22, Link Shared on Social Media)
Chandra J, Armengol de la Hoz MA, Lee G, Lee A, Thoral P, Elbers P, Lee HC, Munger JS, Celi LA, Kaufman DA. A novel Vascular Leak Index identifies sepsis patients with a higher risk for in-hospital death and fluid accumulation. Crit Care. 2022 Apr 11;26(1):103. doi: 10.1186/s13054-022-03968-4. PMID: 35410278; PMCID: PMC9003991.
Link to Article
Link to FULL FREE PDF
Second reason why rate is important: Fluid Responsiveness
The data on how to assess for fluid/volume responsiveness has been covered ad nauseam on this website HERE. To break it down easily, in order to not overload our patients, we need to make sure the fluids we provide them are going to be valuable to increase their cardiac output to be of any use. Looking to see if the blood pressure is pretty isn’t the way to go. Let’s not forget that titrating for a systolic blood pressure rather than looking at the mean arterial pressure is just silly.
Why do you NOT want to use the IV Pump and hit 999cc/hr?
You do NOT want to hit 999cc/hr on the IV pump because that means it is going to take an entire hour to get that liter into the patient. In that hour only 200cc will be in the intravascular space. The rest of it would have said “peace out” and scurried into the extravascular space. Giving fluids like this would not determine fluid responsiveness AT ALL. In fact, it would just likely be causing harm.
Peripheral IV Catheter charts exist such as THIS ONE which show us the flow rate of IV fluids we can administer depending on the gauge of the catheter. For example, if you have a 16 gauge in the forearm, you can run fluids at approximately 180cc/min. Now, if you have your pump set at 999cc/hr, you’re really only delivering 16.65cc/min. That’s less than 10% of the potential of that IV access!
Why would you provide a fluid bolus with a pressure bag?
Depending on the size of the IV access, one can provide fluids faster using a pressure bag. Fast enough to be able to assess for fluid responsiveness and mitigate extravasation of fluids as much as possible. We need to remember that this is one of the holy grails of medicine and we do not have the exact answer for this question at this time.
Since 1995 we’ve known that pressure bags, and even gravity-fed, are superior to the IV pump at 999ml/hr. Stoneham published an in vitro study where he found that in a 16 gauge IV catheter, the mean flow rate on a gravity-fed 100cm height fluid bolus was 3.2cc/s. A little over half a liter was provided in 168 seconds or a bit under 3 minutes.
If you use a 300mm pressure bag at a rate of 5.68cc/s using manual inflation and do math, then you can get the same volume into the patient in approximately 1.5 minutes. This will not allow the fluids to extravasate and the patient will receive a better yield for the fluids they are being provided.
To bring it all back, those 500+cc’s on a pump running at 999ml/hr would take over half an hour to provide.
Conclusions on why to use a pressure infusion bag for a fluid bolus
Maintenance fluids are used too frequently and serve no purpose in the vast majority of patients who receive them. If the decision is made to provide fluids to the patient in resuscitation for hypotension and shock, we should be utilizing pressure bags, or at least to gravity, instead of hanging fluids and just hitting the rate of 999ml/hr and walking away. If one were to do that, the majority of the fluids would be extravasated and potentially causing harm elsewhere in the patients body. Now, I completely understand that there are order sets in place that call for the bolus to be provided by hitting 999 on the pump. Hopefully education to physicians and APP’s such as this can assist to that RN’s are not stuck providing boluses over a pump.
Citations for Fluid Bolus
Lobo DN, Stanga Z, Aloysius MM, Wicks C, Nunes QM, Ingram KL, Risch L, Allison SP. Effect of volume loading with 1 liter intravenous infusions of 0.9% saline, 4% succinylated gelatine (Gelofusine) and 6% hydroxyethyl starch (Voluven) on blood volume and endocrine responses: a randomized, three-way crossover study in healthy volunteers. Crit Care Med. 2010 Feb;38(2):464-70. doi: 10.1097/CCM.0b013e3181bc80f1. PMID: 19789444.
Link to Article (NOT FREE)
Link to FULL FREE PDF
Ragaller MJ, Theilen H, Koch T. Volume replacement in critically ill patients with acute renal failure. J Am Soc Nephrol. 2001 Feb;12 Suppl 17:S33-9. PMID: 11251029.
Link to Article
Link to FULL FREE PDF
Stoneham MD. An evaluation of methods of increasing the flow rate of i.v. fluid administration. Br J Anaesth. 1995 Sep;75(3):361-5. doi: 10.1093/bja/75.3.361. PMID: 7547060.
Link to Article
Link to FULL FREE PDF
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Fluid Bolus Reel
The physician orders a fluid bolus for the patient who is in shock.
We should avoid placing the liter bag on the pump and hitting 999.
I will be oversimplifying but the break down on my website.
The purpose of giving fluids is to increase the blood pressure, right?
Well, MAP = CO x SVR.
CO = HR x SV.
The aim of giving fluids is to improve the stroke volume.
If we hit 999 on the pump, the fluid will not go in fast enough to improve the stroke volume.
Instead, what we do is potentially overload the patient with no benefit.
This is because critically ill patients extravasate 80% of fluids provided within 1 hour.
50% of the fluid infused is lost within 20 to 30 minutes and goes into the interstitial space.
Alternatives include a pressure bag, rapid infusers, or different tubing, amongst others.
Another variable to consider is the size of the IV access.
Assessing the change in stroke volume is one of the definitions of fluid responsiveness.
I know it’s an extra step but ask the ordering clinician if they want the fluids on the pump or faster.
I am aware that we need to change order sets to specify this.
We do not want to cause harm with the fluid bolus. Appreciate your support.