Wednesday, January 12, 2005

Triple Lumen Catheters Are Not Volume Lines

I brought a patient to the operating room recently who had a Type A ascending thoracic aneurysm dissection. She was bleeding into her pericardium and was in tamponade on arrival. She had a radial arterial line that wasn't (in an artery), and two triple lumen central lines--one in a femoral vein and one in an internal jugular vein.

I immediately thought back to my medical school days when I would see patients in the ICU with a GI bleed being transfused with cold, undiluted packed red blood cells through a triple lumen central line....and they were on vasoactive drips for 'hypotension.'

What's my point? Triple lumen catheters are long and narrow (especially compared to Cordis introducer sheaths or products like them made by other manufacturers such as Arrow). Remember the Poiseuille-Hagen equation shows that flow rate is directly proportional to the fourth power of the radius, to the viscosity of the fluid being transfused, and to the pressure gradient established and inversely proportional to the length of the tube. A 9 French introducer sheath can infuse fluid at about 1000 cc/min. Compare that to about 250 cc/min for the 14 gauge lumen of a triple lumen catheter. So it follows, then, that if you need to give someone fluid (like blood) fast, you infuse it through a fat catheter that is short, reduce the viscosity by diluting it and warming it (in the case of packed red blood cells), and apply some pressure by elevating it well above the patient or putting a pressure bag on it. Got it? Good! This might come in handy when you next see a hypovolemic patient...

Friday, December 10, 2004

Parenteral metoclopramide for acute migraine: meta-analysis of randomised controlled trials -- Colman et al. 329 (7479): 1369 -- BMJ

BMJ: Parenteral metoclopramide for acute migraine: meta-analysis of randomised controlled trials -- Colman et al. 329 (7479): 1369

""Conclusions: Metoclopramide is an effective treatment for migraine headache and may be effective when combined with other treatments. Given its non-narcotic and antiemetic properties, metoclopramide should be considered a primary agent in the treatment of acute migraines in emergency departments.""

This works well. I've been using metoclopramide (Reglan) for perioperative migraine for years, ever since learning about it from a Navy ER doc at Balboa. I don't use metoclopramide for post-operative nausea vomiting (prophylactic or treatment), but that's another blog post.

Wednesday, December 1, 2004

How Much Midazolam Is Holding Someone's Hand Worth?

I provided anesthesia for cataract surgery today. For most of today's patients, it was their second eye and they tend to be more nervous the second time. I rediscovered how holding someone's hand is worth at least a milligram or two of midazolam (intravenous sedative).

Saturday, October 16, 2004

Luscious Lips

For longer general anesthetics, anesthesiologists often place a lubricant on the eyes before taping them closed. We tape them closed to avoid corneal abrasions and prevent drying. Lacrilube is the product most commonly used and it contains white soft paraffin, liquid paraffin and lanolin alcohols. Here's the hint: it works great as a lip balm, too! Just a dab on the lips and your patients will roll into the recovery room with shiny, luscious smackers and you'll earn yourself five easy style points, too.

St. Caffeine and Anesthesia

If you're an anesthesiologist or surgeon, a significant number of your patients are caffeine dependent. Being aware of this fact and planning for it will significantly improve your patient's operative experience. In fact, if you're an anesthesiologist or a surgeon, you're probably caffeine dependent, but that another blog post. In my pre-op visits with patients, I ask if they are regular caffeine drinkers, if so, how much, and what happens if they don't have any caffeine on a given day. For patients that report headaches without daily caffeine intake, I plan on administering caffeine.

The most convenient form pre-op is injectible Caffeine and Sodium Benzoate (though tablets are also available). Our formulation comes in a 2 cc vial, of which each cc contains 121mg of anhydrous caffeine. I think of each cc as being the equivalent of one cup of coffee or one can of Diet Coke. Yes, there are studies. Here's one of them: Prophylactic intravenous administration of caffeine and recovery after ambulatory surgical procedures. The cost? About $3.50 per vial. About the same as a tall latte with extra foam (in Europe). I typically administer one cc IV very slow push, and squirt the other cc into the iv bag.

You know what I think the biggest benefit is? It's not just the lack of headache (they weren't expecting a headache when they came in) it's the feeling that they're being well cared for. Sort of like bringing them a warm blanket. Oh, and the nurses will be very impressed, too.

p.s. the title of this post refers to a song by John Gorka called St. Caffeine:

I've seen the light, oh the light I've seen

I've seen the light of St. Caffeine

Of other drugs I am clean

I pray to you St. Caffeine

I moved this over from my personal blog

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