Inhalational anesthetics: Desflurane and sevoflurane
ABSTRACT This article reviews the physico-chemical properties and performance characteristics of the two new potent inhaled anesthetics, desflurane and sevoflurane. Both drugs provide a greater degree of control of anesthetic depth and a more rapid immediate recovery from anesthesia than is currently available with other inhaled agents because of their decreased solubility. Desflurane is currently in widespread clinical use in the United States and parts of Europe. Compared with sevoflurane, it has the additional advantage of being extremely resistant to degradation and biotransformation. However, its pungent odor and tendency to irritate the respiratory tract make it unsuitable for inhalational inductions, and it has been linked to CO production in CO2 absorbents. The sympathetic nervous system activation that occurs with desflurane limits its use in patients with cardiac disease. Otherwise, its hemodynamic and physiologic effects are similar to those seen with isoflurane. Studies of the economics of using desflurane are mixed, although it may offer the advantage of shorter postoperative recovery time. Sevoflurane is currently in widespread clinical use in Japan and parts of South America. The FDA Advisory Panel has recently recommended approval of sevoflurane in the United States, and we can expect the drug to be clinically available in the United States in the second quarter of 1995. Compared with desflurane, sevoflurane has the additional advantage of being nonirritating to the airway; inhalational induction of anesthesia with sevoflurane is achieved rapidly and easily. The instability of sevoflurane with CO2 absorbents and its in vivo biotransformation produce potentially toxic byproducts. These byproducts, including Compound A and fluoride, have been extensively studied, and although the possibility for iatrogenic sequelae from sevoflurane exists, the likelihood of long-term toxicity appears quite low. Phase IV studies are indicated to determine the safety of administering sevoflurane (1) to renally impaired patients and (2) to any patient with fresh gas flows less than 2 L/min. Sevoflurane is otherwise very well tolerated and appears to offer the advantage of rapid and smooth induction and emergence from general anesthesia.
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ABSTRACT: Sevoflurane is an ether inhalation general anaesthetic agent with lower solubility in blood than isoflurane or halothane but not desflurane. The low solubility and the absence of pungency facilitate rapid mask induction; the low blood solubility also expedites "wash-out' and therefore recovery from anaesthesia. Sevoflurane produces dose-dependent CNS, cardiovascular and respiratory depressant effects that generally parallel those of isoflurane. Sevoflurane is degraded by carbon dioxide absorbents to nephrontoxic (in rats) haloalkenes, although renal toxicity has not been observed in humans. Compared with other inhalation anaesthetics, negligible quantities of carbon monoxide are generated from degradation of sevoflurane by carbon dioxide absorbents. Sevoflurane has negligible airway irritant effects, which facilitates a "smooth' induction, even in comparison with halothane in paediatric patients, and makes sevoflurane especially amenable to rapid induction of anaesthesia in adults and children. Emergence, orientation an postoperative cognitive and psychomotor function recovery of paediatric outpatients is singnificantly more rapid from sevoflurane than from halothane anaesthesia. In adult inpatients and outpatients, emergence and orientation are significantly faster after sevoflurane than after isoflurane but not desflurane anaesthesia. Other recovery parameters (e.g. times to sitting, ambulation) occur at similar times after either sevoflurane or desflurane anaesthesia. Recovery of psychomotor function occurs at generally similar times after sevoflurane, isoflurane or desflurane. Compared with propofol, sevoflurane facilitates more predictable extubation times and significantly better postoperative modified Aldrete scores in outpatients, although cognitive and psychomotor recovery occurs at similar times for both agents. As a supplement to opioid anaesthesia during coronary bypass graft surgery or in those at risk for myocardial ischaemia, sevoflurane is comparable to isoflurane. Limited data suggest that it is also as useful as isoflurane for the maintenance of anaesthesia during neurosurgical or obstetric procedures. Sevoflurane is well tolerated by adult and paediatric patients during induction of anaesthesia, with a low incidence of mild airway complications (breath-holding, coughing, excitement and laryngospasm). During rapid induction, it is particularly better tolerated than isoflurane or halothane. Sevoflurane has a lower potential for hepatic injury than halothane. Unlike methoxyflurane, sevoflurane undergoes minimal intrarenal defluorination, which may account for the lack of fluoride ion-induced nephrotoxicity in humans, despite elevated plasma fluoride levels after its use. In summary, sevoflurane provides for a rapid and smooth induction of, and recovery from, anaesthesia. These features combined with its favourable cardiovascular profile should make sevoflurane the agent of choice for inhalation induction in adult and paediatric anaesthesia. Although further clinical evaluation will define the role of this agent relative to that of propofol and desflurane, sevoflurane should also prove to be a valuable alternative anaesthetic agent for adults in both outpatient and inpatient surgery.Drugs 05/1996; 51(4):658-700. · 4.13 Impact Factor
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ABSTRACT: We compared postanesthetic and residual recovery of desflurane versus propofol anesthesia. Twenty volunteers were anesthetized for 1 h at 1-wk intervals with either propofol (induction) plus desflurane (1.25 minimum alveolar anesthetic concentration) in O2 (PD), propofol plus desflurane in N2O-O2 (PDN), propofol plus propofol infusion with N2O-O2 (PPN), or desflurane (induction) plus desflurane in O2 (DD). Awakening and clinical recovery were measured. Psychomotor skills (attention, coordination, reactive skills, and memory) were tested before and 1,3,5, and 7 h after anesthesia. Awakening was fastest in Group PDN. At 1 h after anesthesia, the subjects given desflurane for maintenance (PD, PDN, and DD) performed significantly (P < 0.05-0.01) better in several psychomotor tests compared with those whose anesthesia was maintained with propofol (PPN). However, subjects met criteria for home readiness as fast after PPN as after PDN anesthesia (mean times +/- SE until fitness for discharge were 126 +/- 20, 81 +/- 14, 70 +/- 7, and 106 +/- 14 min after PD, PDN, PPN, and DD, respectively). Awakening and early psychomotor recovery for as long as 1 h after anesthesia is faster after desflurane than after propofol, but there was no difference in time to home readiness or in residual effects thereafter between propofol and desflurane with N2O in O2.Anesthesia & Analgesia 10/1996; 83(4):721-5. DOI:10.1097/00000539-199610000-00010 · 3.42 Impact Factor