I use very little and in specific circumstances. I actually put vasopressin in with the other big guns, epi and norepi. When bolusing I use it .5-1 unit at a time. Even .5 units can give you a robust increase in B.P. I rarely need more than 1-4 units unless I'm dealing with cardiac arrest. If perfusion asks for it I give them 2u in 20cc syringe. They sometimes used it more than I think they should. That's just me though.
I use it almost exclusively in low SVR states:
- Vasoplegic Shock
- Septic Shock/Neurogenic shock/Vasodilatory shock
- Refractory hypotension 2nd to ARB/ACE inhibition
- High Epidural/Spinal (N=0, but if it happens I would use it if Neo isn't doing the trick)
Exceptions to low SVR states:
- Uncontrollable Hemorragic Shock (keep in as much as you can while you fill the tank)- I don't use it in patients who have had a significant drop in Hct over hours.
- Refractory cardiac arrest
In general, if someone is hypovolemic, has refractory hypotension (refractory to neo or ephedrine), and needs a pressor while you administer crystalloids/products, vasopressin will not be at the top of my list. SVR would be high in these people, so I like to choose something that has some Alpha + Beta. If they are tachy I like norepi. If they are not, epi.
As a CA-3, I was bouncing around from heart room to heart room trying to get my hands on as many TEE cases as possible. One of the rooms I popped into was a 85 y/o patient with refractory hypotension. TEE probe in place, then came 2 Units of Vasopressin (likely too much for this guy). Either way, I immediately saw worsening RWMA/LV function. It was like night and day. Corrected the situation with NTG and EPI. Significant improvement. Temporal relationship could not be denied.
I have a healthy respect for vasopressin. It is a great drug, but as most big guns, they have equal potential to fix or hurt someone if not used correctly.
S/E of Vasopressin out of the Handbook of Anesthesia:
Vasoconstriction of coronary, splanchnic, muscular and cutaneous vascular beds.
May cause oliguria, H20 intoxication, pulmonary edema, myocardial ischemia, arrhythmias, abdominal cramps, anaphylaxis, contraction of smooth muscle, gall bladder, urinary bladder and uterus, vertigo, nausea and tremors.
Another experience:
2 months into PP I was on call and got called by surgery to do an ex-lap for lower GI bleed. Long story short, GI had tried their best to control bleeding and ended up putting the patient on Vasopressin after multiple attemps to control the bleeding via scope. Saw him in pre-op. Dude was white as a ghost, shaky, stomach cramps, hypertensive with a hgb of 7.0 (after receiving 6 units on the floor that day). I looked at his gtt's and found vaso going at 0.6U/min.
Back to the OR, opened him up. Bowels looked like shait. They were only getting a trickle of heme traversing them. I turned off the vaso. Within 20 minutes his skin had normal color and his bowels beautifully pinked up. Next lactate was 2.5 from 6.
I know that .6u/m is higher than recommended, but the experience showed me the dramatic effects of Vasopressin. I respect it tremendously.
Skeletal muscle breakdown has been linked to oliguria and worsening renal failure with vasopressin:
http://www.ncbi.nlm.nih.gov/pubmed/6610943
Interesting editorial:
http://www.anesthesia-analgesia.com/content/102/6/1908.2.full
http://www.anesthesia-analgesia.org/content/101/3/830.full?sid=70b305b9-e48d-4775-81a8-4282f5ca867c
Myocardial Ischemia:
http://circ.ahajournals.org/cgi/content/short/83/6/2111
http://www.anesthesia-analgesia.org...html?sid=253a7e73-9f63-4a05-b5dc-4adea2481328
Vasopressin remains a potent tool in the anesthesia arsenal, but I use it with extreme exclusivity.
Noy, to answer your question:
In general if they fit my criteria (low SVR or otherwise), I bolus .5-2U over a 30min interval. I may repeat this once more. If I don't get an adequate result, they go on a drip usually in conjunction with other exogenous catecholamines.
