In this episode I discuss the use of IV fluids for perioperative use including how to decide when to give fluid, the downsides of over resuscitation, whether to use crystalloid or colloid, and whether to use saline or a balanced salt solution such as LR.
Slides to go along with this episode are here: IV Fluids slides
8 thoughts on “Episode 15: IV Fluids”
Great episode. I was curious if there has been a study comparing the use respiratory variation seen on arterial line tracing versus clinical assessment of fluid status as a guidance for fluid resuscitation?
I’m not aware of a study looking at that. I assume by clinical assessment you mean a providers feeling about what the fluid status is but without using any specific method like pulse pressure variation, IVC analysis, systolic pressure variation, etc. In other words, how good is our gut? If you find a study looking at this send it along. Thanks!
I have a question about post op hypotension… So if you say it’s not hypovolemia, and we know it’s caused by surgery, stress and ADH release then do you treat it our leave it? How long should you expect this? how low should you leave it with out attepting pressure drips? Or is there another solution?
Great questions. First, let me be clear, post-op hypotension CAN be due to hypovolemia. The important point is that you shouldn’t ASSUME that it is. It may, or it may not. Urine output is not a good indicator of whether a post-op patient is hypovolemic for the reasons you mention (stress and surgery induced ADH release). There are a variety of ways to try to get an idea as to whether a patient needs volume. The best are dynamic measures. You can look at their heart and IVC with an ultrasound, you can calculate their systolic pressure variation or pulse pressure variation if they are mechanically ventilated with tidal volumes of at least 8cc/kg. If they are not mechanically ventilated you can do a passive leg raise test and look at the change in any of these parameters. If a patient is not volume responsive, giving volume will not help. In that case, if they are hypotensive with normal cardiac function the most common cause is vasodilation from the SIRS response. Norepinephrine is probably the best pressor for this. If they have reduced cardiac function they may need inotropes, like dobutamine or milrinone, but if their pressure is too low for those then epinephrine may be the best option.
In terms of when to treat, the best evidence would indicate you should keep a patient’s MAP>65. So if they are not volume responsive and their MAP is less than 65, start pressors.
The duration of post-op inflammatory response varies based on the type of surgery and the individual patient and, of course, how straight forward their course is. For large abdominal surgeries like whipples you can expect 2-3 days of inflammatory response. For cardiac surgery it is often shorter, maybe 1-2 days.
Often hypotension that is due to post-op inflammation can be treated effectively with a relatively low dose norepinephrine infusion (0.01-0.06mcg/kg/min).
Thanks for listening to the show.
All the best,
Great episode and podcast. Just wanted to correct something that you said in this episode…non-anesthesia related. Wilt Chamberlain learned the underhand free throw technique from hall of famer Rick Barry, not Rick James, who is of course, the super freak:)
Very true, thanks for the clarification!
Really appreciate the episode and accompanying slides. Question: Towards the end when discussing using LR for blood transfusion, you state that precipitation should not be an issue as long as your rate is faster than one unit per every 2 hours. Is that based on experience or literature? I’m taking some of your key points to my medics, and I want to have some good back up information should I get significant challenges from them. Thanks! -Matt
Hi Matt, thanks for the question. This is definitely based on literature. See below:
Safe up to one hour: https://link.springer.com/article/10.1007/s12630-010-9396-z
Safe up to two hours: http://europepmc.org/abstract/med/1866680