Interesting case yesterday. Elderly patient (late 60's) with recent diagnosis of renal CA with mets to brain, lungs and now apparently bone. Other hx: DMII, HTN, CABG x3 a few years ago. Beta-blocked, ARB, steroid therapy, oral antihyperglycemics, lantus, prevacid. No history of GERD prior to the start of chemo/rads and steroid therapy. Pt is under 5 feet and approximately 65kg.

Pt presented for a distal femur excision and TKA from a pathological fracture from a bone tumor. Denies current n/v, claims good exercise tolerance prior to the fx, no angina/sob, sleeps flat, looks a bit pale and fluffy, but not particularly edematous. Normal neuro exam, sounds clear to ausculatation, quiet murmur on right sternal border. Original diagnosis and therapy were at a different facility so we don't have any labs farther back than a couple of days before surgery, which were:

Na 127
K 3.2
BUN/creat 12/0.5
Ca 9.0
H/H 12.4/0.39
WBC 10.4
coags normal

Patient gets admitted and ortho makes an attempt at 'optimization' and pain control. They don't order a morning blood count, but the BMP was essentially unchanged aside from a bump in the K to 4.3. Patient is in preop confused as all get out from the round the clock oxycodone dosing. Patient gets a fem nerve catheter and we head back to the room. Case is pretty smooth except for an almost completely ineffective block and somewhat labile BP as a result - any movement of the leg is incredibly stimulating. Start a fentanyl gtt, give some labetalol a couple of times and things settle down. The first couple hours were done under tourniquet, so blood loss was minimal, but urine was just pouring out. Not counting third-space losses, we were only a few hundred ahead about 2 hours in, when we draw some labs:

pH 7.42, co2 36, o2 229, BE -1, bicarb 23, hgb 9.2, hct 28, Na 125, K 4.2, Ionized Ca 1.18, glucose 147, osmo 269. In: LR 1400. Out: EBL 100, urine 950.

We discuss the labs - the H/H & osmo look like the patient is too wet, but with that abnormal sodium the osmo is going to be screwed up no matter what. We decide to run 'em a bit on the dry side, so cut way back on the fluid and switch to NS. Over the next couple of hours, pressures start dropping to the point that I start a neo gtt, give some neo boluses and cut back on the fentanyl. Not a lot of variability in the waveforms, but the patient is acting a bit on the dry side with a 10-15 bump in HR. Urine output has slowed down, blood loss up now that tourniquet is down. Draw second set of labs:

pH 7.42, co2 32, o2 219, be -3, bicarb 21, Hgb 9.0, hct 27, na 125, k 4.4, ionized ca 1.17, glu 179, lactate 1.0 and osmo 267. Total in: LR 1600, NS 300ish. Total out: EBL 350, u/o 1250.

At this point, I'm kerfuffled. I was expecting the osmo and Na to go up, at least some and the patient is acting quasi-dry. The neo is running at 2.5mg/hr and I'm having to give bumps now and again. I discuss with the MDA and my CRNA - I'm concerned that if the patient really is overloaded still, that giving voluven will only worsen the dilution and possibly send the patient over into an acute hyponatremia that they can't handle. MDA thinks blood is the answer, so we order up a unit. After the blood and a little extra NS go in labs are:

Hgb 10.3, hct 31, Na 125, k 4.6 and osmo 274.

I am able to back off on the neo, down to 1-1.5mg/hr, but it really doesn't make a huge difference in HR and urine output stays at about 100ml/hr (as it had for the last few hours).

So was the patient wet or dry? Should that Na have been corrected before surgery? Should I have given voluven/hextend earlier in the case? Is increasing the osmolarity helpful or harmful in the face of persistent electrolyte abnormalities? What other pre-op or intraop labs would have been beneficial?

I see a couple of things I forgot: when asked whether to use NS from the get-go, MDA said "just use LR." Pre-op BP's were in the 90's to low 100's. No other electrolytes were checked at any point, neither was an EKG done pre-op.

Thanks for the replies!