Podcast Episode 2: UOP-The Best Field Monitor for PFC… and a Word on Hypotensive resuscitation
In this episode Justin introduces the importance of properly using urine output to monitor hemodynamics of both trauma and medical patients by interviewing 2 of our contributing working group members; Dr. Phil Mason Air Force Emergency Medicine Physician and Critical Care Intensivist and Dr. Chris Burns who is a Retired Navy Trauma Surgeon. Both of these doctors have been instrumental in answering the complex questions we have put forth because of their familiarity of our training and equipment available while also putting themselves out there in austere environments from time to time. Thank you both for taking your time to do this podcast.
Check out the show notes and handout below:
Everything You Need to Know About Foley Catheters
Measuring urine output via indwelling Foley Catheter has been called the poor man’s Pulmonary Artery Line which is an invasive diagnostic tool used to measure, among other things, the direct pressures inside the chambers of the heart which can help monitor resuscitation efforts. This field expedient tool is exactly what I need as a medic on the ground; a safe and effective way to monitor my patient using the tools I already have available. As medics we need to get over the stigma of sticking a tube in a guy and the process of keeping it sterile. It is an essential procedure, if done right, to see how your patient is doing. Until we get our own video from our PFC lab up on YouTube, there are plenty of other nursing students who have done this for us. Get familiar with this procedure before deploying or doing a PFC training scenario. Better yet train your junior or one of your other non-medical guys to do it.
A couple things mentioned in the podcast are worth reiterating here:
After insertion you may get a large amount of urine in the tube and bag.
Empty the tube into the bag and empty the bag into a graduated cylinder or a Nalgene you have previously marked down to the mL. What?! It’s sterile right?
This does not count toward hourly output!
Record the amount as your inital out and then flush it.
This is when the hour and your recording begin.
Set your watch or egg timer you included in your PFC kit for 60 minutes.
When the alarm goes off, empty the tube into the bag and the bag into the cylinder.
Record this number down to the cc, as your UOP on your documentation chart for trending.
You should be trending 0.5cc/kilo/hour or about 30-50cc per hour
Thanks for the update. The majority of patients that are able to survive in the hands of most medics are those with traumatic injuries that are of a compressible nature. There are those exceptions where there are slow non compressible bleeders that will either A.) clot with proper care and that can be treated with FWB or blood components. That being said some people would say that the .5cc/kg/hr or 30-50 cc/hr is adequate but on the low end. Would you say there is merit to this? With a traumatically stable patient (all bleeding completely controlled) would you see a benefit in a 1cc/kg/hr output. For example, blast injury right upper leg, hemostasis achieved, wound debridement done, dressing change done, all other treatments done, and your sitting on this patient for 48 hours. Would this have any effect on the persons ability to return to a state of homeostasis, fight off infection, etc. etc. quicker perhaps.
Any idea on how long someone can go with inadequate urine output until there is irreparable damage such as a situation where you’re playing the hypotensive resuscitation game due to a non-compressible injury?
-Kevin
Kevin raises a good point and makes an important distinction between managing patients with ongoing, non-compressible hemorrhage and those in whom hemostasis has been achieved. We certainly don’t let patients remain hypotensive in a trauma ICU after they have been operated on so I would not advocate continuing hypotensive resuscitation when hemorrhage has been controlled in the field by non-surgical means, whether that be tourniquets, good wound packing, or whatever. So in the case of extremity or soft tissue wounds where you can readily determine if there is ongoing hemorrhage, I would feel pretty good about resuscitating to a normal blood pressure. It would be OK to have a urine output (UOP) >30-50 cc’s in those cases and it might even be beneficial in patients with significant muscle injury who are at risk of renal failure from myoglobinuria. I think it is a more difficult decision when the bleeding is not readily identified, as in the case of abdominal injuries, long bone fractures, etc. In these cases I think I would continue to target the low normal blood pressure (MAP 55-65) and UOP 30 – 50 cc/hr. I would not necessarily interpret that level or UOP to be inadequate. I think most of us would feel pretty good with that UOP for the long haul even in trauma center ICU setting, though we would admittedly also be following other parameters such as hemoglobin and lactate that you may not have available in the field.
As far as how long you can sustain a patient with hypotensive resuscitation- I have no idea. If anybody does please share it. I do know that you can’t live very long with ongoing hemorrhage fueled by continuous resuscitation, even if that resuscitation is with FWB. For that reason I would favor staying the course (MAP 55-65, UOP 30-50) until the patient can be evacuated rather than start pushing for higher numbers in a setting where it is very difficult to detect and treat ongoing bleeding. Also, I think it is important to remember that what we are calling hypotensive resuscitation is different than the TCCC concept of hypotensive resuscitation. Our endpoints of MAP and UOP are physiologically sound and take adequacy of circulation into account, whereas TCCC is more focused on hemostasis knowing that the circulation can be restored to normal after the patient reaches surgical care.
These are my thoughts for what they are worth. I am not aware of any hard science to guide us here but there may well be some that I am missing. I would welcome any additional comments or information.
Phillip Mason