I Prefer the TIVA Approach
David Barinholtz, MD
Mobile Anesthesiologists, LLC
Back in the 1970s, I never went for the tri-mode stereo. Rather, I liked to listen to my music on a system comprised of a turntable, cassette player, tuner, receiver, equalizer, and speakers. The reason, as any audiophile will tell you, was simple. I was not willing to sacrifice sound quality for convenience. Today, when I administer anesthesia in the outpatient setting-be it general or monitored anesthesia care-I stick to the same philosophy. I prefer total intravenous anesthesia (TIVA) over a balanced inhalational technique because I do not want to sacrifice quality of care for convenience.
Just as the custom stereo system allowed me to control each source of sound, TIVA allows me to control each component of anesthesia independently-including hypnosis, amnesia, analgesia and, when needed, muscle relaxation. Because each IV agent typically does one thing and one thing only,* I can achieve the exact results I need throughout the procedure. For example, at any time I can increase or decrease the propofol infusion rate to deepen or lighten hypnosis without affecting the other components, such as analgesia or muscle relaxation.
With inhalational techniques, this precise level of independent control is not possible. Although the volatile agents can serve as "complete anesthetics," they achieve each component of anesthesia at a different anesthetic depth. If the provider wants to use a volatile agent as the sole anesthetic for a procedure that requires profound muscle relaxation, for example, he or she would need to administer at least 2.0 to 2.5 MAC.** However, only 1.5 to 2.0 MAC is needed for analgesia, 1.0 to 1.5 MAC is needed for unconsciousness, and just 0.5 to 0.75 MAC is needed for amnesia. Thus, the provider would need to administer a relative overdose of the volatile agent. Of course, the higher the MAC, the greater the risk of a complication, such as hypotension, because the volatile agents are potent myocardial depressants and vasodilators. Although adjunct narcotics and muscle relaxants can decrease MAC requirements, this does not make the side effect issue disappear.
Another important reason I prefer TIVA is an improved recovery profile. Several clinical studies1,2,3,4,5 suggest that a propofol-based TIVA regimen, when compared with inhalational-based technique, is associated with less postoperative nausea and vomiting (PONV). In my experience, TIVA is also associated with faster wake-up and discharge; over 90 percent of our patients go directly to phase II recovery from the OR. This is largely due to propofol's lack of cumulative effect and antiemetic properties. The longer the case, the more clinically significant this difference becomes. I have administered propofol for six hours in a nasally intubated dental patient, and the patient was discharge-ready without PONV within one hour after the procedure. Such results are commonplace in our practice.
A third reason I prefer TIVA for general anesthesia in the outpatient setting is that it enables the patient to maintain a higher level of normal physiologic function. With most balanced inhalational techniques, patients are paralyzed, intubated, and mechanically ventilated. During recovery, these patients may be apneic, and it can be difficult to ascertain if they have incomplete reversal of paralysis, a narcotic overdose, or both. This complicates PACU recovery. With TIVA, along with neurophysiologic monitoring (which I consider essential), patients breathe spontaneously and rarely require intubation or even an LMA, even when the procedures are as invasive as breast reduction or abdominoplasty. By continuously monitoring respiratory rate and end-tidal CO2 concentrations, I can rationally titrate narcotics and prevent apnea. I also avoid potent paralytic agents like succinylcholine and rocuronium that can ablate spontaneous ventilation, and I avoid reversal agents such as neostigmine, which may contribute to PONV.
I use TIVA for all types of procedures including facial plastic surgery, abdominoplasties, breast reductions, laparoscopic surgery, strabismus surgery, and dental surgeries on adults and children. When intubation is necessary, I typically avoid muscle relaxants altogether, and when patients do require an inhalational induction, I switch to TIVA as soon as I start the IV. The only time I routinely use a total inhalational-based regimen is for short pediatric procedures like myringotomy tube insertion or nevus removal. In these cases, it is difficult to refute the psychological benefits of a "gas" induction (with or without oral premedicants), and brief exposure to inhalational agents generally does not cause PONV.
Although there is never a singular approach to anesthesia, here is an example of how I typically approach an abdominoplasty. I administer approximately 2 mg midazolam for anxiolysis and amnesia. I then give an up-front bolus of ketamine (typically 20 to 50 mg) to induce analgesia and a dissociative state, thereby lessening narcotic and propofol requirements. Next, I administer approximately 100 ?g fentanyl for further analgesia (in anticipation of surgical stimulus and/or local anesthetic injections) and then begin the induction of hypnosis with propofol. I always use bispectral index monitoring (BIS) to assess the degree of hypnosis. Initially, I aim for a BIS level in the 30s to 40s which, with this regimen, generally allows for a smooth start. Once surgery is underway, I allow the BIS level to rise to the 50-to-60 range for the remainder of the case. This allows for adequate hypnosis while avoiding an anesthetic overdose. By improving the accuracy of propofol titration, the BIS monitor has allowed me to reduce the typical induction dose by an average of one-third and maintenance infusion levels by about 20 percent. I then insert a standard Guedel oral airway, which I modify to administer oxygen and to sample respiratory gases. I continue to administer propofol as dictated by the BIS and narcotic boluses as dictated by the respiratory rate and end-tidal CO2. During rectus muscle repair, I administer approximately 25 percent of an intubating dose of rocuronium if additional muscle relaxation is needed (often it is not). I have found this gives adequate muscle relaxation for repair without paralyzing the diaphragm. Since this dosage wears off in 15 to 20 minutes, it does not require reversal. At the end of the procedure, the surgeon inserts a pain pump that reduces postop narcotic requirements. Typically, these patients awaken within a few minutes and move to a recliner, where they generally spend approximately one hour in PACU before becoming discharge-ready. This technique depends on adequate amounts of lcal anesthetic.
For procedures that require complete muscle relaxation, like laparoscopic cholecystectomy, I perform a standard intubation and mechanical ventilation. I follow pretty much the same protocol, but I give a standard intubating dose of rocuronium and 100 mg lidocaine IV to help blunt the hemodynamic response associated with instrumentation of the airway.
Clearly, TIVA is more labor-intensive than balanced inhalational regimens because it requires vigilant monitoring of neurophysiologic, respiratory, and cardiovascular status with continual titration of multiple agents. Some also claim TIVA is more expensive, especially for longer cases, but this argument does not apply to us. The price of propofol, which represents the single largest drug cost in our practice, has decreased 30 to 40 percent since introduction of the generic version. The typical drug cost for a two-hour anesthetic is approximately $55 in our practice, plus $15 for the BIS probe. I believe any direct cost increase over a low-flow inhalational regimen is countered, if not, outstripped by the excellent recovery we see in our practice. Our patients typically sit with an Aldrette score of 9 or 10 within 5 to 10 minutes after completion of surgery, and a full 95 percent are discharged within one hour. The remainder are gone within two hours, even after lengthy cases. Thanks to TIVA, we enjoy a high level of both patient and surgeon satisfaction.
*Of course there are exceptions, e.g. ketamine.
**MAC, which helps quantify the dose of anesthetic gases, is the minimum alveolar concentration of a gas necessary to assure 50 percent of patients will not move in response to painful stimuli such as a skin incision. IV anesthetics have a "MAC equivalent," which is the concentration of anesthetic in the blood that provides the same effect.
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