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Emergence "Delirium" After Sevoflurane Anesthesia

1999; Lippincott Williams & Wilkins; Volume: 88; Issue: 6 Linguagem: Inglês

10.1213/00000539-199906000-00020

1526-7598

Lynda Wells, Deborah K. Rasch,

Cardiac, Anesthesia and Surgical Outcomes

"Delirium" during emergence from sevoflurane anesthesia has been well documented in children [1-4], but not in adults, and its nature and etiology remain unclear. We report four cases of sevoflurane emergence delirium in which patients were able to describe their experiences. Case 1 A 24-yr-old, 62-kg man, ASA physical status I, presented for irrigation and debridement of his right fifth digit and split-thickness skin grafting after a crush injury to his hand. Preoperatively, he was noted to be extremely anxious. He had no significant medical or surgical history. Significantly, there was no history of psychiatric disorder. The patient denied psychoactive substance use or abuse, but expressed a great fear of needles and agreed to an inhaled induction. Anesthesia was induced smoothly with O2, N2 O, and sevoflurane (8% reduced to 2%) via a face mask and was maintained with these anesthetics. Fentanyl 50 [micro sign]g IV was given. No other medications were given. Vital signs were stable throughout the case. On emergence from anesthesia, the patient was tremulous, hyperactive, and violent toward those who approached him, and he appeared to be hallucinating. He leapt from the stretcher and tried to leave the operating room (OR) suite. He repeatedly asked to see his wife, who came while he was confined to one corridor of the OR suite. She reassured and calmed him such that he returned to the stretcher and was moved to the postanesthesia care unit. This entire episode lasted 20 min. The remainder of his recovery was unremarkable. In a subsequent discussion with the patient, he reported having full recall of all postoperative events. He said that he was convinced that everyone was lying to him and that he thought he was being taken to have surgery, during which people would intentionally cause him harm. He reported feeling terrified, wanting to protect his wife and to escape from the hospital. Specifically, he denied experiencing any pain associated with the surgical procedure. Case 2 An 8-yr-old, 34-kg girl, ASA physical status I, presented for incision and drainage of a submandibular lymph node abscess. Her only medication was amoxicillin and clavulanate potassium. Midazolam premedication (1.5 mg IV) was given through an existing venous cannula, and the patient appeared drowsy, calm, and cooperative. She separated well from her parents and did not appear distressed during monitor placement or induction of anesthesia in the OR. After she breathed 100% O2 via a face mask, anesthesia was induced with 60 mg of propofol IV and was maintained with O2, N2 O, and sevoflurane (2%-3%). Topical lidocaine applied to the airway facilitated endotracheal intubation. Muscle relaxant was not used. Fentanyl 100 [micro sign]g IV was given in divided doses. Vital signs were stable throughout the case. The trachea was extubated while the patient was asleep in the left lateral position. On awakening, the patient was extremely agitated and distressed. She was kicking, screaming, and declaring that she was very frightened; she did not want the mask near her face or to go to sleep. At this time, there was no face mask. After 15 min, the patient became calm, and she was able to appreciate that she was in the recovery room and unharmed. On direct questioning, she reported soreness at the surgical site, but she was not distressed by this. Case 3 A 4-yr-old, 22-kg boy, ASA physical status I, presented for dental rehabilitation. Oral midazolam premedication 0.5 mg/kg produced a sedated, cooperative patient who separated calmly from his parents. He accepted monitor placement and application of the face mask. Sevoflurane O2 inhaled induction was smooth (8% reduced to 4%). As the patient was losing consciousness, he stated that he could not breathe, but he did not struggle against the mask. Nasotracheal intubation was facilitated by topical lidocaine, and a total of 2 [micro sign]g/kg fentanyl was given for a period of 2 h. Vital signs were stable throughout. On emergence from anesthesia, the patient was extremely agitated and repeatedly screamed, "I'm afraid! Don't touch me! I'm afraid!", although he was not being touched or restrained. He could not be calmed by anyone, including his parents, and the severity of his distress was such that the anesthesiologist believed it necessary to sedate him in the recovery room with fentanyl and midazolam until he fell asleep. He reawakened calm and orientated. No further medications were required. Case 4 A 3-yr-old, 18-kg girl, ASA physical status II, presented for revision of a ventricular-peritoneal shunt. She had no history of anesthetic complications or postoperative dysphoria. Premedication with oral midazolam 0.5 mg/kg produced a willing, cooperative child who tolerated mask induction with sevoflurane well. After IV cannula placement, pancuronium 0.1 mg/kg and fentanyl 2 [micro sign]g/kg were administered. Endotracheal intubation was uneventful, and the patient was stable throughout the procedure while anesthetized with 2.5% sevoflurane. The patient's trachea was extubated while she was awake, but she was agitated and inconsolable. She could not be calmed by her parents; in fact, she became worse when they touched her. On direct questioning, 20-30 min later, when she was calm and oriented, the patient described being "very, very frightened" and said, "I thought you [the anesthesiologist] were going to hurt me … but I don't think that now." She denied having pain. Discussion Our observation of emergence delirium after sevoflurane administration is that patients are agitated, restless, combative, and extremely frightened, and they do not seem to be fully cognizant of their surroundings. Children refuse to be comforted, often even by their parents. The explanation given for this behavior is that recovery of consciousness from sevoflurane is so rapid that postoperative analgesia is not yet effective and patients are responding to pain [1-5]. Terror is not a usual pain-related behavior, and our patients' reports confirm that pain was not significant. Rapid return to consciousness does not automatically lead to agitation or disorientation. Awakening from propofol anesthesia is notably rapid, smooth, and pleasant. Patients 1 and 2 were disorientated as to time, believing themselves to be awaiting surgery, and they manifested paranoid ideation. Patients 3 and 4 were younger, and although it is not known whether they were disorientated as to time, their terror may also have been a manifestation of paranoid ideation. Our adult patient had clear and complete recall of his delusions and behavior on awakening from anesthesia. He was apologetic and upset by his behavior. He was concerned that it be understood that his physical aggression was not characteristic but was driven by severe paranoid ideation that he could not resist. It is likely that this patient will continue to remember this event. All the pediatric patients described regained their usual personalities, and it is likely that they, too, can recall the events during emergence, even if they do not verbalize them. It would be interesting to know whether occurrence of this organic psychosis after sevoflurane anesthesia is associated with subsequent behavioral abnormalities, either perioperatively or independent of this setting. We hypothesize that sevoflurane delirium may be associated with misperception of environmental stimuli. Additionally, certain mechanistic processes underlying sevoflurane's mode of action may have contributed to the genesis of these phenomena. Most patients experiencing emergence delirium are children who cannot explain their perceptions. Postoperative agitation in children is often interpreted as pain, and increasing analgesia often leads to increased sedation and a "calmer" patient. Those who manifest this behavior, however, may be experiencing delusions similar to those observed in our patients. We observed that anxiolytic premedication and effective analgesia in pediatric patients does not necessarily prevent emergence delirium. In our experience, the use of high concentrations of sevoflurane to delay emergence cannot be relied on to avert this outcome. Maintaining anesthesia with a different volatile drug after induction with sevoflurane has also been ineffective. Many studies that comment on the emergence characteristics of sevoflurane [1-5] have been conducted with differing interpretations of essentially similar observations. Constant et al. [6] demonstrated that the electroencephalogram pattern in children anesthetized with sevoflurane differs from that of individuals anesthetized with halothane. Thus, apart from anesthesia, these drugs may have different central effects, which may explain the different emergence characteristics between the two. Ketamine, droperidol, and scopolamine are also associated with postoperative dysphoria, anxiety, and agitation. Ketamine acts by inhibition of glutamine at N-methyl-D-aspartate receptors. Droperidol inhibits dopamine 1 and 2 receptors. Scopolamine acts by increasing central acetylcholine concentrations. Sevoflurane has not been reported to act at a particular receptor [7]. An electronic search of the peer-reviewed literature failed to reveal any articles addressing neurotransmitter changes under sevoflurane anesthesia, which might account for these emergence characteristics. In summary, emergence delirium after sevoflurane anesthesia is a short-lived, acute organic mental state of uncertain etiology. Future studies exploring the neuropsychopharmacological properties of sevoflurane, its metabolites, and other inhaled anesthetics may explain these behavioral patterns.