5% dextrose and cardiac outputs with a swan ganz catheter

[BethanyBSNRN]

Hi everyone,

I am a semi new grad working in a heart and vascular surgical ICU. In my ICU we take all of the fresh open heart patients that our hospital has.

In the post op period for fresh open hearts we frequently check cardiac output/ index with a swan ganz catheter. I was just wondering if anyone could tell me why 5% dextrose is used in this process?

[Esme12, ASN, BSN, RN]

I have used both actually...evidence shows no difference and it remains a practice/facility preference.http://www.wtrs.com/downloads/Research_CathLab_Calculations.pdf

[Biffbradford]

When we were doing bolus cardiac outputs, we always used normal saline because I suppose that's what the manufacturer stated to use. There is a computation constant that had to be used, and maybe it's dependent on the type of fluid used? All post cardiac surgery fluids were based on D5.45 or D5.2n/s (2 different hospitals, two different sets of orders despite it being the same surgeons). So, with the continuous cardiac output monitors it we had D5.45 or D5.2 running (with or without K/Mg depending on lab values).

[blucrna]

I've been meaning to grab one of our s/crna's about this. As soon as we get the pt post op we change all the dextrose bags to Ns. It just seems like a no brainer to start with NS given the need for tight glucose control

[Dodongo, APRN, NP]

We use NS in my ICU. I would think the major problem with a solution containing dextrose would be the possible raise in blood sugar.

[CPT_Charlios]

I gues it's facilitity dependant. In my facility we use D5w as the CO injectate due to its thermodilution properties. NS can be used but can produce a 2% error.

"Cardiac Output (CO) measurements are done in CTICU using the closed system CO-Set. Room temperature injectate (D5W 18-25 C) is the standard method. Measurement of CO with a pulmonary artery catheter is done using the thermodilution technique:

• A known volume of D5W at a temperature that is colder than blood temperature is injected into the right atrial port of the catheter
  
• The temperature of this injectate solution is measured as it enters the catheter lumen
  
• The blood temperature is measured at the tip of the catheter in the pulmonary artery
  
• During cardiac output measurement, the temperature of the right atrial blood drops after the bolus. When this colder blood reaches the tip of the pulmonary artery catheter, the change in the blood temperature over time produces a cardiac output curve. The rise in the curve represents the falling temperature, while the decline in the curve is during temperature recovery
  
• The computer program incorporates the volume of injectate (usually 10 ml), the injectate temperature and the model of catheter (lumen size and length) into the temperature change curve to produce a cardiac output value. The algorhithm also incorporates the specific gravity of the D5W solution, therefore, it is important that D5W is used.
  
• Both Paceport and VIP catheters use the same computation constant. This is automatically adjusted based on injectate temperature."
  

[bisson]

You can use both, it might be an institution preference. We do use D5 for cardiac output, and our post op maintenance fluid is D5 1/3 NS. we follow AACN guidelines for our practice, but we also have very particular surgeon preferences.

to address the blood sugar issues, all of our patients are on a tight sugar control, and once anyone goes over 150 we start them on a glucommander protocol/ drip. biggest pain in the behind.