Desflurane Should Not Des-appear

To the Editor In the opinion piece entitled “Desflurane Should Des-appear: Global and Financial Rationale,” Dr Meyer1 outlines his reasoning for the removal of the inhaled anesthetic from our anesthetic armamentarium. He cites minimal clinical benefit, negative environmental impact, and high cost. It is important to begin my response with a declaration that I have been a speaker for Baxter and desflurane. However, I also have years of experience using desflurane as a maintenance anesthetic. Furthermore, I am familiar with the literature supporting my clinical experience. I also understand and agree with the role that we as anesthesiologists should play as stewards for a safe and sustainable environment. But before we can remove desflurane from clinical practice, we must find an anesthetic that can offer at least equal benefit to our anesthetized patients. Many anesthesiologists, such as I, have based entire anesthetic plans in high-risk patient populations undergoing high-risk surgeries around the benefits of this inhaled anesthetic with great success over the years. Dr Meyer1 opines there is a lack of significant clinical benefit with the use of desflurane. To begin this discussion, we must first agree as to when a patient is truly “awake” and safe. Sundman et al2 demonstrated that at 25% MACawake (the minimum alveolar concentration of an inhaled anesthetic needed to suppress a response, usually eye opening, to a verbal command in 50% of subjects), or at about 5%–10% MAC (the minimum alveolar concentration of an inhaled anesthetic needed to suppress movement to a noxious stimulus, such as surgical incision, in 50% of subjects), over 20% of patients still had pharyngeal dysfunction with sevoflurane and isoflurane. They also showed that pharyngeal dysfunction was markedly increased with subhypnotic doses of propofol. Eger and Shafer,3 using simulation, showed that the times to achieve MACawake were similar with isoflurane, sevoflurane, and desflurane, especially for exposures of <120 minutes. However, the times to achieve lighter anesthetic levels when pharyngeal function is normalized were notably different between isoflurane and sevoflurane when compared to desflurane with desflurane occurring more rapidly.3 Is this relevant in clinical practice? McKay et al4 demonstrated that patients receiving desflurane had earlier awakening and were better able to protect their airway, as noted by not coughing or drooling when swallowing 20 mL of water 2 minutes after following commands, when compared to sevoflurane. The findings were quite dramatic with 100% of the desflurane group having normal pharyngeal function but <50% of the sevoflurane group achieving that level.4 When looking at patients with significant comorbidities, Bilotta et al5 demonstrated a quicker recovery of cognitive function and, more importantly, earlier normalization of pH and Paco2 in morbidly obese patients undergoing craniotomy when receiving desflurane. As for the environmental impact of desflurane, it was quoted that globally, health care was responsible for 4.6% of greenhouse gas emissions, and anesthetics made up 2% of that. Therefore, anesthetics account for 0.09% of greenhouse gas emissions worldwide. Although this is incredibly small percentage wise, I agree that it is a nonnegligible number. However, it is small enough to consider techniques and devices to reduce that further rather than eliminating a commonly used anesthetic. Reducing fresh gas flow on induction and emergence as well as utilizing a closed, or near closed, circuit anesthetic can virtually eliminate the environmental contamination and be performed safely.6 Understandably, a true closed circuit anesthetic may be impractical, but a near closed circuit anesthetic is quite feasible. Furthermore, Dr Meyer1 failed to mention the utilization of waste gas elimination devices now available to dramatically lower the release of desflurane into the environment whether by destruction or capturing the molecules for reuse.7 Dr Meyer1 also did not discuss the impact to the environment of other anesthetics which will likely be utilized in larger quantities if desflurane is removed. First, sevoflurane, although to a lesser extent, has a negative environmental impact. More importantly, we cannot underemphasize the negative environmental effects of the intravenous anesthetics (eg, propofol) with the creation of medical waste including syringes, plastic tubing, and needles, as well as the utilization of electrical devices for their delivery leading to a small but present greenhouse gas impact. We also know that propofol is spilled at high amounts into our environment, is not naturally degraded, and is toxic to wildlife.8 Therefore, we can all agree that there is a negative environmental impact with the use of anesthetics as a whole, but to attribute all of it to one anesthetic with devices already in place to reduce that impact ignores many other contributors to the problem. As for the cost with the use of desflurane, the pharmaceuticals and equipment we use come with a high cost when caring for an anesthetized patient. However, anesthesia accounts for about 5% of total operating room costs with the majority being surgical equipment and employee wages and benefits. Therefore, with operating room costs estimated at $36/min, anesthesia costs are about $1.80/min.9,10 When comparing the cost difference between desflurane and sevoflurane, De Medts et al11 state that “when the absolute amounts of agent mentioned above are considered, it can be appreciated that the difference in cost between both drugs is close to being trivial if they are used at the lower end of the fresh gas flow spectrum.” Furthermore, we again have to discuss intravenous drug waste, not only as a contributor to the environmental impact of anesthetics, but as a contributor to anesthetic cost. Weinger12 studied intravenous anesthesia drug waste in a single university hospital over a 2-week period. The study concluded that $1802 were wasted over that period or $10.86/case. Furthermore, this was felt to be underestimated by up to 40% since not all syringes could be accounted for.12 Therefore, with the ability to use low flow or closed circuit anesthesia and a potential reduction in intravenous anesthetic waste, a desflurane-based anesthetic could prove to be of comparable cost or even less than other anesthetics and anesthetic techniques. In conclusion, I respect my colleague’s thoughts as well as his concern for the environment. But it is unfair to place the blame solely on 1 anesthetic and to play down the positive attributes of the agent that allow us to care for, at the highest level, our increasingly more challenging patients. With data showing a quicker wake up and earlier airway protection—especially in patients with significant comorbidities, ways of effectively reducing the environmental impact, and potentially minimal cost difference, desflurane should continue to be available for clinical use. Joseph Frederick Answine, MDDepartment of Anesthesiology and Perioperative MedicinePennsylvania State University HospitalHershey, PennsylvaniaRiverside Anesthesia AssociatesHarrisburg, PennsylvaniaDepartment of AnesthesiologyUniversity of Pittsburgh Medical Center Pinnacle CampusesHarrisburg, Pennsylvania[email protected]