Outpatient Surgery Magazine

No Guarantees - March 2017 - Subscribe to Outpatient Surgery Magazine

Outpatient Surgery Magazine, providing current information on Surgical Services, Surgical Facility Administration, Outpatient Surgery News and Trends, OR Excellence and more.

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Page 25 of 138

I began a propofol-ketamine (PK) clinical trial in 1992, using propofol hypnosis to block keta- mine hallucinations or dyspho- rias. Over the next year, I watched in amazement as my first 50 PK patients quickly emerged from anesthesia with no need for opioids. Until then, I hadn't heard about N-methyl, D- aspartate (NMDA) receptors, much less their critical midbrain loca- tion. Over the next 5 years and 1,200-plus patients, I continued to observe the same effectiveness with the same 50 mg ketamine dose, whether in 100-pound female patients or 250-pound male patients. Ketamine, which prevents transmission of painful sensation to the cortex by blocking midbrain NMDA receptors, is the only IV anesthetic not given on a per-body-weight basis. The effective dissociative dose of ketamine isn't related to body weight. The adult brain weighs about 3 to 4 pounds and doesn't vary with body weight. The midbrain is a very small part of the adult brain, and the NMDA receptors are a very small part of that very small part. A 50 mg dose of ketamine saturates 98 to 99% of those midbrain NMDA receptors. "Nifty fifty" Now, for the last 25 years, I've never begun a case without what I call the "nifty fifty"— 50 mg IV ketamine 2 to 3 minutes before stimula- tion, injection or incision. The propofol, incrementally titrated — either to loss of lid reflex/loss of verbal response or to a BIS reading Anesthesia Alert AA 2 6 • O U T PA T I E N T S U R G E R Y M A G A Z I N E • M A R C H 2 0 1 7 AN ODE TO PK My Life's Work In 9 Words Measure the brain Preempt the pain Emetic drugs abstain — Barry L. Friedberg, MD

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