RESUMO
BACKGROUND: Unexpected awareness is a rare but well-described complication of general anesthesia that has received increased scientific and media attention in the past few years. Transformed electroencephalogram monitors, such as the Bispectral Index monitor, have been advocated as tools to prevent unexpected recall. METHODS: The authors conducted a power analysis to estimate how many patients would be needed in an appropriately powered study to demonstrate the Bispectral Index monitor reduces awareness, as well as a cost analysis to assess the cost of using the monitor for this purpose alone. RESULTS: If unexpected recall is rare (1 in 20,000), it will require a large study to demonstrate that the monitor reduces awareness (200,000-800,000 patients), and the cost of using it for this purpose alone would be high ($400,000 per case prevented). If awareness is common (1 in 100), then the number of patients needed in a study to demonstrate that the monitor works becomes tractable (1,000-4,000 patients), and the cost of using the monitor for this purpose alone becomes lower ($2,000 per case prevented). Because there are reported cases of awareness despite Bispectral Index monitoring, the authors are certain that the effectiveness of the monitor is less than 100%. As the performance of the monitor decreases from 100%, the size of the study needed to demonstrate that it works increases, as does the cost of using it to prevent awareness. CONCLUSION: The contention that Bispectral Index monitoring reduces the risk of awareness is unproven, and the cost of using it for this indication is currently unknown.
Assuntos
Anestesia Geral , Conscientização , Eletroencefalografia , Custos e Análise de Custo , Eletroencefalografia/economia , Humanos , Monitorização Fisiológica/economia , Monitorização Fisiológica/métodosRESUMO
Studies continue to support that a process for screening patients prior to their planned anesthesia and surgery can optimize both the status of the patient, decreasing delays and cancellations, and optimize the use of resources, ensuring that needed testing is completed and unneeded testing is avoided.
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Understanding and complying with the guidelines of the American Society of Anesthesiologists will help ensure high-quality patient care, increase levels of patient safety, and minimize medico-legal risk. The author discusses important standards and guidelines for the administration of general anesthesia and sedation/analgesia in the office-based setting and compares the requirements of the different accrediting organizations. (Aesthetic Surg J 2001;21:573-575.).
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Cervical spine instability in the neurologically intact patient following penetrating neck trauma has been considered rare or non-existent. We present a case of a woman with an unstable C5 fracture without spinal cord injury after a gunshot wound to the neck. Considerations regarding the risk of cervical spine instability are discussed, as well as suggestions for a prudent approach to such patients.
Assuntos
Vértebras Cervicais/lesões , Instabilidade Articular/etiologia , Lesões do Pescoço/complicações , Fraturas da Coluna Vertebral/etiologia , Ferimentos por Arma de Fogo/complicações , Tratamento de Emergência/métodos , Feminino , Humanos , Imobilização , Instabilidade Articular/diagnóstico por imagem , Instabilidade Articular/terapia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Fatores de Risco , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/terapia , Fusão Vertebral , Tomografia Computadorizada por Raios XAssuntos
Apresentação Pélvica , Parto Obstétrico/métodos , Serviços Médicos de Emergência/métodos , Gêmeos , Adulto , Feminino , Humanos , GravidezRESUMO
Gunshot wounds (GSWs) pose significant medicolegal and forensic issues. Mistakes have been made regarding identification of gunshot wounds. We present a case of an atypical gunshot wound and review contact, near contact, intermediate, and distant wounds. There is an objective terminology to describe GSWs in the Emergency Department.
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Medicina Legal , Ferimentos por Arma de Fogo , Adulto , Serviço Hospitalar de Emergência , Feminino , Humanos , Terminologia como AssuntoRESUMO
BACKGROUND: Sevoflurane is a volatile general anesthetic that differs in chemical nature from the gaseous anesthetic nitrous oxide. In a controlled laboratory setting, the authors characterized the subjective, psychomotor, and analgesic effects of sevoflurane and nitrous oxide at two equal minimum alveolar subanesthetic concentrations. METHODS: A crossover design was used to test the effects of two end-tidal concentrations of sevoflurane (0.3% and 0.60%), two end-tidal concentrations of nitrous oxide (15% and 30%) that were equal in minimum alveolar concentration to that of sevoflurane, and placebo (100% oxygen) in 12 healthy volunteers. The volunteers inhaled one of these concentrations of sevoflurane, nitrous oxide, or placebo for 35 min. Dependent measures included subjective, psychomotor, and physiologic effects, and pain ratings measured during a cold-water test. RESULTS: Sevoflurane produced a greater degree of amnesia, psychomotor impairment, and drowsiness than did equal minimum alveolar concentrations of nitrous oxide. Recovery from sevoflurane and nitrous oxide effects was rapid. Nitrous oxide but not sevoflurane had analgesic effects. CONCLUSIONS: Sevoflurane and nitrous oxide produced different profiles of subjective, behavioral, and cognitive effects, with sevoflurane, in general, producing an overall greater magnitude of effect. The differences in effects between sevoflurane and nitrous oxide are consistent with the differences in their chemical nature and putative mechanisms of action.
Assuntos
Analgésicos não Narcóticos/farmacologia , Anestésicos Inalatórios/farmacologia , Cognição/efeitos dos fármacos , Éteres/farmacologia , Éteres Metílicos , Óxido Nitroso/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Adulto , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Masculino , Memória/efeitos dos fármacos , SevofluranoRESUMO
BACKGROUND: Studies of the effects of barbiturates on the modulation of pain have produced mixed results. In a prospective, double-blind, randomized, placebo-controlled trial, we studied the effects of thiopental at presumed steady-state, "conscious sedation" levels on cold-pressor-induced pain in 12 healthy volunteers. METHODS: Five drug conditions were used, each condition consisting of an injection (either drug or placebo) with a 20-min infusion and a 160-min recovery period. The conditions were placebo (saline), thiopental targeted to three effect-site concentrations, and fentanyl (1.4 micrograms/kg), as a positive control to verify test sensitivity to analgesic drugs. The three thiopental concentrations were modeled (STANPUMP) to achieve effect-site concentrations of 5, 7.5, and 10 micrograms/ml using a bolus and a three-step continuous infusion. Five minutes into the infusion period and 115 min after the infusion period was terminated, subjects immersed their forearms in ice cold water for 3 min while pain and behavioral assessments were recorded. RESULTS: Thiopental at the highest dose produced a significant reduction (P < 0.05) in self-reported pain intensity both at 5 min into the infusion period and at 115 min after termination of the infusion. Fentanyl reduced pain intensity during the first immersion only. Thiopental changed subjects' moods and psychomotor performance in a dose-related fashion. CONCLUSIONS: Our laboratory results do not support the long-held belief that barbiturates are "antanalgesic" or hyperalgesic, at least for cold-pressor-induced pain.
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Afeto/efeitos dos fármacos , Analgésicos/farmacologia , Anestésicos Intravenosos/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Tiopental/farmacologia , Adulto , Estudos Cross-Over , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Humanos , MasculinoRESUMO
The purpose of this study was to characterize the effect of a painful stimulus on morphine and butorphanol effects in healthy non-drug abusing volunteers. Thirteen subjects with no history of opiate dependence participated in a randomized, placebo-controlled, double-blind, crossover trial in which each subject received saline, 2 mg/70 kg butorphanol, and 10 mg/70 kg morphine, IV, in each of two conditions, periodic forearm immersions into either ice-cold water (2 degrees C) or into warm water (37 degrees C). Both opioids reduced self-reported ratings of pain intensity, indicative of analgesia. Several of the subjective effects of morphine were attenuated either during or in between cold-water immersions, including visual analog scale ratings of "coasting (spaced out)," "high (drug "high")," "sleepy (drowsy, tired)," and "lightheaded". In contrast, some of butorphanol's subjective effects were increased by the cold-water manipulation. Morphine impaired psychomotor performance during one of the warm-water immersions, but not during the cold-water immersions. Psychomotor impairment induced by butorphanol was not affected by water temperature. This study provides evidence that opioid effects can be modulated by a painful stimulus in humans.
Assuntos
Analgésicos Opioides/farmacologia , Butorfanol/farmacologia , Morfina/farmacologia , Entorpecentes/farmacologia , Dor/psicologia , Desempenho Psicomotor/efeitos dos fármacos , Adulto , Analgesia , Temperatura Baixa , Feminino , Humanos , Imersão/fisiopatologia , Masculino , Dor/etiologia , Medição da Dor , Fatores de Tempo , ÁguaRESUMO
The purpose of this study was to characterize the reinforcing, subjective and psychomotor effects of nitrous oxide in healthy volunteers with different alcohol histories. Subjects were divided into two groups: light drinkers (n = 9) and moderate drinkers (n = 10). A choice procedure was used in which subjects first sampled placebo and a given concentration of nitrous oxide, and then chose between the two. Nitrous oxide concentration varied across the four-session experiment from 10-40%. Besides choice, subjective and psychomotor effects served as dependent measures. The majority of subjective effects of nitrous oxide, and its psychomotor-impairing effects, did not vary as a function of drinking group. However, a Wilcoxon rank sum test showed that the median number of times moderate drinkers chose nitrous oxide (three) was significantly higher than the median number of times light drinkers chose nitrous oxide (one). This study provides suggestive evidence that the reinforcing effects of nitrous oxide are modulated by alcohol history.
Assuntos
Consumo de Bebidas Alcoólicas/psicologia , Depressores do Sistema Nervoso Central/farmacologia , Óxido Nitroso/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Administração por Inalação , Adulto , Afeto/efeitos dos fármacos , Depressores do Sistema Nervoso Central/administração & dosagem , Método Duplo-Cego , Feminino , Humanos , Masculino , Óxido Nitroso/administração & dosagem , Reforço PsicológicoRESUMO
The reinforcing and subjective effects of brief (about 1.5 min) exposures to nitrous oxide, ranging from inspired concentrations of 20-80% in oxygen, were examined in 11 healthy volunteers. A choice procedure was used in which during each of four sessions, subjects first sampled a given concentration of nitrous oxide and placebo oxygen, and then chose between the two. 20, 40, 60 and 80% nitrous oxide were chosen by five, four, three, and three subjects, respectively--these choice levels did not exceed that of chance. All concentrations had psychoactive effects, and in general, concentration-related subjective effects were found. We conclude that in a medical setting, nitrous oxide inhaled in a manner similar to that when used recreationally in a naturalistic setting, does not function as a reinforcer across a wide range of concentrations, in subjects with a modest lifetime history of psychoactive drug use.
Assuntos
Anestésicos Inalatórios/farmacologia , Motivação , Óxido Nitroso/farmacologia , Reforço Psicológico , Adulto , Relação Dose-Resposta a Droga , Feminino , Humanos , MasculinoRESUMO
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.
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Período de Recuperação da Anestesia , Anestesia por Inalação , Anestesia Intravenosa , Anestésicos Inalatórios/administração & dosagem , Anestésicos Intravenosos/administração & dosagem , Isoflurano/análogos & derivados , Propofol/administração & dosagem , Desempenho Psicomotor/efeitos dos fármacos , Vigília/efeitos dos fármacos , Adulto , Anestésicos Inalatórios/farmacologia , Anestésicos Intravenosos/farmacologia , Atenção/efeitos dos fármacos , Estudos Cross-Over , Desflurano , Seguimentos , Humanos , Isoflurano/administração & dosagem , Isoflurano/farmacologia , Memória/efeitos dos fármacos , Destreza Motora/efeitos dos fármacos , Óxido Nitroso/administração & dosagem , Oxigênio/administração & dosagem , Alta do Paciente , Propofol/farmacologia , Estudos ProspectivosRESUMO
The reinforcing and subjective effects of fentanyl, an opioid analgesic, were tested in ten healthy volunteers without histories of drug abuse, as a function of the temperature of a water bath in which the volunteers' forearms were immersed. The temperatures were body-temperature (37 degrees C), moderately cold (10 degrees C), and very cold (2 degrees C). A discrete-trial choice procedure was used in which, in each session, volunteers sampled 50 micrograms of fentanyl (delivered as a bolus via an infusion pump) and saline, and then on three successive trials, chose between the two. Volunteers then had to immerse their non-dominant forearm in the water bath 5 min after a drug delivery. Fentanyl was chosen on 77% of choice occasions in the 10 degrees C and 2 degrees C water conditions, which was significantly different from chance levels, and on 60% of choice occasions in the 37 degrees C water condition, which did not differ from chance levels. Several subjective effects of fentanyl were also modulated by the temperature of the water bath. We conclude that in the context of a painful stimulus, 50 micrograms of fentanyl functions as a reinforcer in non-drug abusers.
Assuntos
Analgésicos Opioides/farmacologia , Nível de Alerta/efeitos dos fármacos , Temperatura Baixa , Fentanila/farmacologia , Imersão , Motivação , Adulto , Método Duplo-Cego , Euforia/efeitos dos fármacos , Feminino , Humanos , Bombas de Infusão , Masculino , Limiar da Dor/efeitos dos fármacosRESUMO
The effects of saline and intravenous midazolam (0.5, 1, and 2 mg per 70 kg) in combination with intravenous fentanyl (0.1 mg/70 kg) were examined on pain induced by a cold pressor test. Healthy volunteers (six females, six males) were enrolled in a prospective, double-blind, randomized, crossover trial in which mood and psychomotor performance were also examined. Five minutes and 135 min postinjection subjects immersed their forearm in ice cold water for 3 min while assessments of pain were recorded. During the first immersion, subjects reported significantly lower pain intensity and bothersomeness ratings after having been injected with fentanyl, relative to the saline condition, but the addition of midazolam neither increased nor decreased pain reports. During the second immersion (approximately 2.5 h postinjection) pain ratings did not differ between the drug and saline conditions. Mood-altering and psychomotor-impairing effects of the drug combination were dose related. We conclude that midazolam at the doses and route of administration tested neither potentiates nor decreases the analgesia produced by fentanyl in a cold-pressor pain assay.
Assuntos
Analgésicos Opioides/farmacologia , Ansiolíticos/farmacologia , Fentanila/farmacologia , Midazolam/farmacologia , Medição da Dor/efeitos dos fármacos , Adulto , Afeto/efeitos dos fármacos , Analgésicos Opioides/administração & dosagem , Pressão Sanguínea/efeitos dos fármacos , Cognição/efeitos dos fármacos , Temperatura Baixa , Estudos Cross-Over , Método Duplo-Cego , Interações Medicamentosas , Fentanila/administração & dosagem , Humanos , Injeções Intravenosas , Desempenho Psicomotor/efeitos dos fármacosRESUMO
STUDY OBJECTIVE: To determine whether subanesthetic doses of propofol have analgesic effects in healthy volunteers. DESIGN: Prospective, double-blind, placebo-controlled, randomized, crossover trial. SETTING: Human psychomotor performance laboratory within our anesthesia and critical care department. SUBJECTS: 12, non-drug abusing volunteers, aged 22 to 38 years. INTERVENTIONS: Five drug conditions were used in which a loading injection was followed by a 20-minute infusion period: placebo [saline (Intralipid)] injection, Intralipid infusion; propofol 0.125 mg/kg injection, propofol 12.5 mcg/kg/min infusion; propofol 0.25 mg/kg injection, propofol 25 mcg/kg/min infusion; propofol 0.5 mg/kg injection, propofol 50 mcg/kg/min infusion; fentanyl 1.4 mcg/kg injection (positive control), Intralipid infusion. Five minutes into the infusion period and 115 minutes after the infusion period was terminated, subjects immersed their forearms in ice-cold water for three minutes while pain assessments were recorded. MEASUREMENTS AND MAIN RESULTS: Propofol at the two higher doses during part of the first immersion produced a significant reduction (p < 0.05) in pain intensity and bothersomeness ratings. However, relative to fentanyl, the analgesia was mild. Propofol did not affect any ratings on the 15-item short-form McGill Pain Questionnaire, whereas fentanyl reduced 10 of the ratings. CONCLUSION: Our laboratory results are consistent with the commonly accepted clinical practice of supplementing propofol with an opioid in conscious sedation procedures to provide a satisfactory level of pain relief.
Assuntos
Anestésicos Intravenosos/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Hipnóticos e Sedativos/farmacologia , Medição da Dor/efeitos dos fármacos , Propofol/farmacologia , Adulto , Anestésicos Intravenosos/administração & dosagem , Anti-Inflamatórios não Esteroides/administração & dosagem , Temperatura Baixa , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Imersão , Injeções Intravenosas , Masculino , Propofol/administração & dosagem , Estudos ProspectivosRESUMO
A crossover, double-blind trial was conducted using eleven healthy volunteers to determine whether and the degree to which acute drug tolerance occurred to the subjective, cognitive, and psychomotor effects of a range of subanesthetic nitrous oxide doses (0, 10, 20, 30, and 40%). There was little evidence of acute drug tolerance to the subjective measures or to the cognitive/psychomotor impairing effects of nitrous oxide at any of the concentrations tested over the course of the 120-min inhalation.
Assuntos
Afeto/efeitos dos fármacos , Anestésicos Inalatórios/farmacologia , Cognição/efeitos dos fármacos , Óxido Nitroso/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Administração por Inalação , Adulto , Estudos Cross-Over , Relação Dose-Resposta a Droga , Método Duplo-Cego , Tolerância a Medicamentos , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Oxigênio/sangueRESUMO
Transnasal butorphanol is effective in relieving migraine and postoperative pain. The extent to which this drug preparation impacts on cognitive and psychomotor performance, as well as mood, has not been examined. Accordingly, the cognitive and psychomotor, subjective, and physiological effects of two clinically relevant doses of transnasal butorphanol (1 and 2 mg) were compared to that of placebo, and a common analgesic drug combination given for pain relief in ambulatory settings, 600 mg of acetaminophen and 60 mg of codeine, in healthy volunteers (n = 10). The larger transnasal butorphanol dose impaired psychomotor performance for up to 2 h, and produced subjective effects for up to 3 h. The smaller dose had no psychomotor-impairing effects, but had subjective effects (including increased ratings of "sleepy"). All three active drug conditions including miosis. These laboratory results suggest that patients should use caution when using the 1-mg dose of transnasal butorphanol, and should curtail certain activities if they administer the 2-mg dose of transnasal butorphanol for analgesia.
Assuntos
Afeto/efeitos dos fármacos , Analgésicos Opioides/farmacologia , Butorfanol/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Acetaminofen/administração & dosagem , Acetaminofen/farmacologia , Administração Intranasal , Adulto , Analgésicos Opioides/administração & dosagem , Butorfanol/administração & dosagem , Codeína/administração & dosagem , Codeína/farmacologia , Cognição/efeitos dos fármacos , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Masculino , Miose/induzido quimicamente , Placebos , Estudos Prospectivos , Sono/efeitos dos fármacosRESUMO
The analgesic, subjective, and psychomotor effects of 0, 10, 20, 30, and 40% nitrous oxide in oxygen were studied in 10 volunteers to determine if acute tolerance developed differentially to these variables. In this prospective, randomized, crossover, double-blind study, volunteers inhaled either placebo (100% oxygen) or one of the aforementioned doses of nitrous oxide for 120 min. During this period, volunteers immersed their non-dominant forearm, for 3 min, in ice-cold water at 25, 70 and 115 min from the onset of the inhalation. At other prescribed time intervals throughout the session, mood and psychomotor performance were assessed. Subjects reported less pain intensity from the cold-water stimulus and reported the pain bothered them less as a function of increasing nitrous oxide dose; in addition, this analgesia was significantly less as the inhalation period progressed (i.e., acute tolerance). Some subjective effects of nitrous oxide that could be considered hedonic in nature (elation, drug liking) also showed evidence of acute tolerance. In contrast, other subjective effects and the psychomotor-impairing effects of nitrous oxide did not change significantly during the inhalation period (i.c., no acute tolerance). The differential acute tolerance observed in this study suggests that different effects of nitrous oxide may be mediated by different neurochemical substrates.