Cardiac output and the pharmacology of general anesthetics: a narrative review

The relationship between cardiac output and anesthetic drugs is important to anesthesiologists, since cardiac output determines the speed with which a drug infused into the bloodstream reaches its target and the intensity of the drug's effect. But rather than focus on how anesthetic drugs affect cardiac output, this narrative review focuses on how changes in cardiac output affect the pharmacokinetics and pharmacodynamics of general anesthetics during the three phases of anesthesia. At induction, an increase in cardiac output shortens both the onset time of propofol for hypnosis and the neuromuscular blocking effect of rapid-acting neuromuscular blockers, favoring the conditions for rapid sequence intubation. During maintenance, changes in cardiac output are followed by opposite changes in the drug plasma concentration of anesthetic drugs. Thus, an increase in cardiac output followed by a decrease in the plasma concentration of the anesthetic could expose the patient to a real risk of intraoperative awakening, which can be avoided by increasing the dose of hypnotic drugs. At emergence, an increase in cardiac output secondary to an increase in pC02 allows for a more rapid recovery from anesthesia. The pC02 can be increased by adding CO2 to the respiratory circuit, lowering the ventilatory rate, or placing the patient on partial rebreathing. Finally, the reversal action of sugammadex for rocuronium-induced neuromuscular block can be shortened by increasing the cardiac output.

La relación entre el gasto cardíaco y los fármacos anestésicos es importante para los anestesiólogos puesto que el gasto cardíaco determina la velocidad con la cual un medicamento que se infunde al torrente sanguíneo llega a su diana y la intensidad del efecto del agente. Pero en lugar de concentrarnos en cómo los fármacos anestésicos afectan el gasto cardíaco, esta revisión narrativa se enfoca en cómo los cambios en el gasto cardíaco afectan la farmacocinética y la farmacodinámica de los agentes anestésicos generales durante las tres fases de la anestesia. En el momento de la inducción, un incremento en el gasto cardíaco acorta tanto el tiempo de inicio del efecto del propofol para la hipnosis como el efecto del bloqueo neuromuscular causado por los bloqueadores neuromusculares de acción rápida, favoreciendo las condiciones para la intubación de secuencia rápida. Durante la fase de mantenimiento, los cambios en el gasto cardíaco vienen seguidos de cambios opuestos en la concentración plasmática del medicamento de los agentes anestésicos. Por lo tanto, un aumento del gasto cardíaco, seguido de una reducción en la concentración plasmática del anestésico, podría exponer al paciente a un riesgo real de despertar intraoperatorio, lo cual puede evitarse aumentando la dosis de los fármacos hipnóticos. En la educción, un aumento en el gasto cardíaco secundario al incremento en el pCO2 permite una recuperación más rápida de la anestesia. El pCO2 puede aumentar agregando CO2 al circuito de la respiración, reduciendo la tasa ventilatoria, o colocando al paciente en re-inhalación parcial. Finalmente, la acción de reversión de sugammadex en caso de bloqueo neuromuscular inducido por rocuronio, puede acortarse aumentando el gasto cardíaco.

Intranasally Administered Adjunctive Dexmedetomidine Reduces Perioperative Anesthetic Requirements in General Anesthesia

PURPOSE: Intranasal dexmedetomidine is an effective sedative for premedication and is regularly used to reduce preoperative tension and anxiety in children. This study aimed to assess the effect of intranasally adjunctive dexmedetomidine on perioperative sedative and analgesic requirements in adults. MATERIALS AND METHODS: Patients were randomly divided into four groups to receive preoperative administration of saline, intranasal dexmedetomidine 1 µg/kg and 2 µg/kg, and intravenous dexmedetomidine 1 µg/kg, respectively. Propofol and remifentanil were target-controlled infused to maintain intraoperative bispectral index at 45-55 and blood pressure at baseline value±20%. Sufentanil was administered to maintain postoperative visual analogue scale ≤3. Perioperative anesthetics requirements were compared using nonparametric tests. RESULTS: Intranasal dexmedetomidine significantly attenuated propofol requirements for anesthesia induction and maintenance in a dose-dependent manner. Patients given intranasal dexmedetomidine 2 µg/kg required less remifentanil for anesthesia maintenance. The first postoperative request for sufentanil analgesia was delayed in patients given intranasal dexmedetomidine 2 µg/kg. The anesthetics-sparing effect of intranasal dexmedetomidine was significantly weaker than intravenous dexmedetomidine at the same dose of 1 µg/kg. The incidences of adverse events, including hemodynamic instability and delayed recovery, were comparable with and without intranasal dexmedetomidine. CONCLUSION: Intranasal administration of dexmedetomidine can reduce perioperative anesthetic requirements, and a dose of dexmedetomidine 2 µg/kg produces a better effect in adults. The anesthetics-sparing effect of intranasal dexmedetomidine 1 µg/kg is less than that with the same intravenous dose of dexmedetomidine.

Anesthesia for esophageal endoscopic mucosal resection / 中华消化内镜杂志

Objective To observe efficacy and safety of 2 ways of intravenous anesthesia in endoscopic mucosal resection (EMR) for early esophageal cancer and its precancerous lesion.Methods A total of 140 patients with early esophageal cancer and its precancerous lesion undergoing EMR were enrolled and randomized into 2 groups, with 70 patients in each.Midazolam and propofol were used for group Ⅰ, while midazolam and etomidate were used for group Ⅱ.Vital signs, anesthetic effect, recovery time during the therapy, intra-operative and post-operative adverse reactions were compared.Results Anesthesia with both methods could reach the need for safe EMR.The blood pressure and heart rate of patients in group Ⅰ significantly decreased during the therapy, while no significant difference was found in those of group Ⅱ, but which was significantly different from those of group Ⅰ at some parts of the observation point (P＜0.05).Pulse oxygen saturation of all patients during the procedure was within normal range.No significant difference was found between 2 groups in recovery time.The incidence of muscle tremor or myoclonus in group Ⅱ was significantly higher than that of group Ⅰ, but the incidence of bradycardia and hypotension in group Ⅱ was lower than that of group Ⅰ (P＜0.05).Several patients complained pain, nausea and dizziness after therapy, but there was no significant difference between two groups. Conclusion Anesthesia with propofol and etomidate can both be applied to digestive endoscopy.Etomidate shows advantages in more stable hemodynamics.

Efeitos do propofol sobre o sistema de condução cardíaca: [revisão] / Efectos del propofol sobre el sistema de conducción cardíaco: [revision] / Effects of propofol on the cardiac conduction system: [review]

JUSTIFICATIVA E OBJETIVOS: Alguns estudos têm demonstrado que o uso do propofol é, algumas vezes, associado a bradiarritmias ou reversão de arritmias para ritmo sinusal. Essa propriedade do propofol sugere interferência no Sistema de Condução Cardíaco (SCC). CONTEÚDO: Realizou-se revisão com base nos principais artigos contemporâneos que englobam o uso do propofol na presença de arritmias cardía cas. Os autores discorrem sobre os mecanismos fisiopatológicos das taquiarritmias supraventriculares (TSV) e as eventuais interferências causadas pelo propofol sobre o SCC. CONCLUSÕES: Os estudos realizados até então parecem indicar que, provavelmente, o propofol interfere nas TSV automáticas (pelo menos em crianças), mas não nas taquiarritmias em que o mecanismo seja de reentrada.

BACKGROUND AND OBJECTIVES: Some studies have demonstrated that the use of propofol is occasionally associated with bradyarrhythmias or reversion of arrhythmias to sinus rhythm. This property of propofol suggests interference with the Cardiac Conduction System (CCS). CONTENTS: A review of the main contemporary articles on the use of propofol in the presence of cardiac arrhythmias was undertaken. The authors describe pathophysiological mechanisms of supraventricular tachyarrhythmias (SVT) and occasional interferences caused by propofol on the CCS. CONCLUSIONS: The studies undertaken so far seem to indicate that propofol probably interferes in automatic SVT (at least in children), but not in reentrant tachyarrhythmias.

JUSTIFICATIVA Y OBJETIVOS: Algunos estudios han demostrado que el uso del propofol es algunas veces, asociado a bradiarritmias o a reversión de arritmias para ritmo sinusal. Esa propiedad del propofol nos sugiere una interferencia en el Sistema de Conducción Cardíaco (SCC). CONTENIDO: Se realizó una revisión en base a los principales artículos contemporáneos que engloban el uso del propofol cuando ocurren arritmias cardíacas. Los autores nos hablan sobre los mecanismos fisiopatológicos de las taquiarritmias supraventriculares y las eventuales interferencias causadas por el propofol sobre el SCC. CONCLUSIÓN: Los estudios realizados hasta ahora parecen indicar que probablemente, el propofol interfiere en las TSV automáticas (por lo menos en niños), pero no en las taquiarritmias en que el mecanismo sea de reentrada.

Evaluation of patient-controlled intravenous analgesia with remifentanil for labor / 中华全科医师杂志

The study intended to evaluate the efficacy and safety of patient-controlled intravenous analgesia with remifentanil for labor. Three hundred and two parturients at 37 -42 week of gestation received remifentanil (0. 1μg · kg-1 ·min-1 ) as patient-controlled intravenous analgesia for labor (analgesia group) and their clinical results were compared with those of 221 parturients in labor without intravenous analgesia (control group). Maternal monitoring, including pain scores(VAS), delivery mode, side effects, laboring time was performed for both groups. There was a significant decrease (P ＜0. 01) of pain scores in analgesia group compared with those in control group. Parturients in analgesia group experienced a significantly shorter first stage, than those in the control group ( P ＜ 0. 01). There were no differences between two groups in the rate of cesarean section and instrumental delivery. And there were no significant differences for newborns with Apgar scores less than 7 at the point of one minute. Patient-controlled intravenous analgesia with remifentanil for labor is an effective and safe procedure, which can significantly relieve pain, shorten first stage of labor and has no effect on the delivery mode and Apgar scores of neonates.

Remifentanil versus Sufentanil em infusão contínua em intervenções cirúrgicas videolaparoscópicas: estudo comparativo / Continuous infusion of remifentanil versus sufentanil in videolaparoscopic surgeries: a comparative study

JUSTIFICATIVA E OBJETIVOS: A infusão contínua (IC) de remifentanil na técnica de anestesia venosa total é prática comum. Já o sufentanil em IC para cirurgias de curta/média duração tem sido pouco utilizado. O objetivo desse estudo foi comparar duas técnicas de anestesia venosa total, utilizando remifentanil ou sufentanil em IC, quanto ao comportamento anestésico no intra-operatório e às características da recuperação anestésica em pacientes submetidos à videolaparoscopia. MÉTODO: Participaram desse estudo 60 pacientes divididos em 2 grupos iguais (GR e GS). O GR foi induzido com remifentanil IC e o GS com sufentanil em bolus associado à IC. A IC de remifentanil era desligada ao fim da cirurgia, enquanto a IC de sufentanil, 20 minutos antes. Os pacientes receberam no intra-operatório cetoprofeno e dipirona. Como analgésico de resgate na sala de recuperação pós-anestésica (SRPA) foi utilizado tramadol. Foram analisados as variações da pressão arterial média (PAM) e freqüência cardíaca (FC), o tempo de despertar, o consumo de propofol, as intercorrências na SRPA e o tempo de permanência na SRPA. RESULTADOS: A média da PAM foi maior no GS em relação ao GR (91,9 × 77,6, p < 0,0001). A incidência de dor foi significativamente maior no GR em relação ao GS (22 × 1 paciente, p < 0,0001). A incidência de NVPO foi maior no GR em relação ao GS (10 × 2 pacientes, p = 0,0098). A média do tempo de permanência na SRPA foi maior no GR em relação ao GS (76 × 49 min, p < 0,0001). CONCLUSÕES: O controle hemodinâmico foi satisfatório nos grupos. A IC de sufentanil promoveu melhor controle da dor no pós-operatório com menor consumo de analgésico de resgate; conseqüentemente, houve menor incidência de NVPO e menor tempo de permanência na SRPA.

BACKGROUND AND OBJECTIVES: Continuous infusion (CI) of remifentanil is common in total intravenous anesthesia. On the other hand, CI of sufentanil for short/medium-term surgeries has not been widely used. The objective of this study was to compare two techniques of total intravenous anesthesia, using CI of remifentanil or sufentanil, regarding their intraoperative behavior and characteristics of recovery of patients undergoing videolaparoscopic surgeries. METHODS: Sixty patients, equally divided in 2 groups (RG and SG), participated in this study. Continuous infusion of remifentanil was used for anesthetic induction in RG, while a bolus of sufentanil associated with CI of this drug was used in SG. The CI of remifentanil was discontinued at the end of the surgery, while the CI of sufentanil was discontinued 20 minutes before the end of the surgery. Patients received ketoprofen and dypirone intraoperatively. Tramadol was used for rescue analgesia in the recovery room. Variations of mean arterial pressure (MAP) and hard reate (HR), time for awakening, propofol consumption, intercurrences in the recovery room, and time of stay in the recovery room were analyzed. RESULTS: Mean MAP was greater in SG than in RG (91.9 × 77.6, p < 0.0001). The incidence of pain was significantly greater in RG than on SG (22 × 1 patient, p < 0.0001). The incidence of postoperative nausea and vomiting (PONV) was greater in RG than in SG (10 × 2 patients, p < 0.0098). The mean time of stay in the recovery room was greater in RG than in SG (76 × 49 min, p < 0.0001). CONCLUSIONS: Hemodynamic control was satisfactory in both groups. Continuous infusion of sufentanil promoted better postoperative pain control with decreased consumption of rescue analgesic and, consequently, reduced incidence of PONV and reduced time of stay in the recovery room.

JUSTIFICATIVA Y OBJETIVOS: La infusión continua (IC) de remifentanil en la técnica de anestesia venosa total es una práctica común. Ya el sufentanil en IC para cirugías de corta/media duración ha sido poco utilizado. El objetivo de este estudio fue el de comparar dos técnicas de anestesia venosa total, utilizando remifentanil o sufentanil en IC, en cuanto al comportamiento anestésico en el intraoperatorio y en cuanto a las características de la recuperación anestésica en pacientes sometidos a la videolaparoscopía. MÉTODO: Participaron en el estudio 60 pacientes divididos en 2 grupos iguales (GR y GS). El GR fue inducido con remifentanil IC y el GS con sufentanil en bolus asociado a IC. La IC de remifentanil se desconectaba al final de la cirugía, mientras que la IC de sufentanil 20 minutos antes. Los pacientes recibieron en el intraoperatorio cetoprofeno y dipirona. Como analgésico de rescate en la sala de recuperación pos anestésica (SRPA) se usó el tramadol. Fueron analizadas las variaciones de la PAM y FC, tiempo de despertar, consumo de propofol, intercurrencias en la SRPA y tiempo de permanencia en la SRPA. RESULTADOS: El promedio de la PAM fue mayor en el GS con relación al GR (91,9 × 77,6, p < 0,0001). La incidencia de dolor fue significativamente mayor en el GR con relación al GS (22 × 1 paciente, p < 0,0001). La incidencia de NVPO fue mayor en el GR con relación al GS (10 × 2 pacientes, p = 0,0098). El promedio del tiempo de permanencia en la SRPA fue mayor en el GR en con relación al GS (76 × 49 min, p < 0,0001). CONCLUSIONES: El control hemodinámico fue satisfactorio en los grupos. La IC de sufentanil generó un mejor control del dolor en el pos operatorio con menor consumo de analgésico de rescate, por lo tanto, se registró una menos incidencia de NVPO y un menor tiempo de permanencia en la SRPA.

Efeito do propofol associado à efedrina no tempo de latência do cisatracúrio / Effect of propofol in combination with ephedrine upon the onset time of cisatracurium

OBJETIVOS: Este estudo teve por objetivo avaliar a eficácia da efedrina na prevenção dos efeitos hemodinâmicos induzidos pela associação do propofol e do remifentanil, assim como os efeitos sobre o tempo de latência do cisatracúrio. MÉTODOS: Sessenta pacientes com idade entre 18 e 52 anos, estado físico ASA I ou II, foram divididos em três grupos, aleatoriamente: G I - propofol 1 por cento; G II - propofol 1 por cento + efedrina 0,5 mg.ml-1 e G III - propofol 1 por cento + efedrina 1,0 mg.ml-1 (velocidade de infusão igual a 180 ml.h-1), até a perda da consciência. Administrou-se remifentanil (0,5 mg.kg-1.min-1) e cisatracúrio na dose de 0,15 mg.kg-1. Foram registrados os dados demográficos, os sinais vitais (PAS, PAM, PAD, FC e SpO2) e o tempo de latência do cisatracúrio. RESULTADOS: Os grupos foram homogêneos com relação aos dados demográficos. Houve diminuição estatisticamente significativa dos valores de PAS, PAM, PAD e FC, um e três minutos após a administração do propofol, porém sem significado clínico importante e sem diferença entre os grupos. As medianas para os tempos de latência do cisatracúrio foram: 178 s (G2 e G3) e 183 s (G1), mas sem diferença significante entre os grupos. CONCLUSÃO: Não houve diminuição clinicamente importante dos parâmetros hemodinâmicos avaliados nos grupos que receberam ou não a efedrina e o tempo de latência do cisatracúrio foi o mesmo para os diferentes grupos.

OBJECTIVE: The onset time of neuromuscular blocking drugs is partially determined by circulatory factors, including muscle blood flow and cardiac output. The aim of the present paper was to: 1) compare the haemodynamic effects of adding different doses of ephedrine to an induction dose of propofol and remifentanil. 2) onset time of cisatracurium. METHODS: Sixty patients were randomly allocated into three groups: G1 - 1 percent propofol; G2 - 1 percent propofol + 0.5 mg.ml-1 ephedrine and G3 - 1 percent propofol + 1.0 mg.ml-1 ephedrine. All patients received continuous infusion of remifentanil (0.5 mg.kg-1.min-1). The rate of propofol infusion was 180 ml.h-1 until loss of consciousness and a loading dose of cisatracurium (0.15 mg.kg-1) was then given. After induction of anesthesia, the ulnar nerve was stimulated supramaximally every 10s, and the evoked twitch response of the adductor pollicis was recorded by accelerometry. RESULTS: There was no statistical difference between groups with respect to age, weight, dose of propofol administered and onset time of cisatracurium (tables 1, 2). Heart rate, SpO2, systolic, diastolic and mean blood pressures were compared at 1 and 3 min post-induction. There were statistical differences in HR, SAP, DAP and MAP, without significant adverse clinical effects. CONCLUSIONS: There were no clinically important decreases in the hemodynamic parameters evaluated in the groups receiving ephedrine or not, and the onset time of cisatracurium was the same for all groups.

Preoperative Anxiety and Propofol Requirement in Conscious Sedation for Ovum Retrieval

The purpose of the present study was to evaluate the correlation among the trial number of in vitro fertilization (IVF), preoperative anxiety, and propofol requirement for conscious sedation. One hundred and twenty six Korean women undergoing oocyte retrieval were enrolled. The target-controlled infusion by the anesthesiologist was conducted with initial target propofol concentration of 2.5 microgram/mL, which was manipulated until the sedation score 3 and desired clinical end point were achieved. A weak correlation was observed between visual analogue scale (VAS) anxiety and the dose of propofol required for the induction of conscious sedation (r=0.22, p=0.0192). A weak correlation was also found between VAS anxiety and the sedation time needed to reach the proper conscious sedation level for the procedure (r=0.181, p=0.0484). Multiple regression analysis showed that VAS anxiety, preoperative baseline prolactin level, and cortisol level had statistically significant effects on the propofol induction dose for target controlled conscious sedation. We concluded that the induction dose and time requirements for propofol in anesthesiologist- controlled conscious sedation be modified based on the preoperative anxiety level and the baseline blood concentration of stress hormone, cortisol and prolactin.

Anestesia en la ventana aorto-pulmonar

Se realiza un estudio retrospectivo de 9 niños menores de 2 años operados de ventana aorto-pulmonar en el Cardiocentro del Hospital Pediátrico Docente "William Soler", durante el período de 1986 a 1994. El fentanyl fue el agente más utilizado en la inducción de la anestesia (8 pacientes, 89 %) y se empleó en todos los pacientes durante el mantenimiento, lo que aportó gran estabilidad hemodinámica. Las complicaciones encontradas fueron el síndrome de bajo gasto cardíaco, broncoespasmo, hipertensión pulmonar y arritmias cardíacas. En todos los pacientes se utilizó el protocolo para el manejo de la hipertensión pulmonar. No hubo fallecidos durante el transoperatorio ni en el posoperatorio inmediato.

A retrospective study of 9 children under 2 operated on of aorto-pulmonary window at the Heart Center of "William Soler" Pediatric Teaching Hospital from 1986 to 1994 was conducted. Fentanyl was the most used agent in the induction of anesthesia (8 patients, 89 %) and it was administered to all patients during maintenance, which made possible a great hemodynamic stability. The complications found were the syndrome of low cardiac output, bronchospasm, pulmonary hypertension and cardiac arrhythmias. The protocol for the management of pulmonary hypertension was used with all patients. Deaths were not reported either during the transoperative or in the immediate postoperative.

Neuroprotective Effects of Propofol, Ketamine and Propofol-ketamine after Transient Forebrain Ischemia in the Rat / 대한마취과학회지

BACKGROUND: Intravenous anesthetics such as propofol and ketamine have been known to have neuroprotective effects. However, the combination of these drug is not known. This study was conducted to determine the neuroprotective effects of propofol, ketamine or both after transient forebrain ischemia. METHODS: Twenty Sprague-Dawley rats (250-300 gm) were used. Anesthesia was induced with 4% isoflurane in oxygen and then maintained with 1 - 2% isoflurane in oxygen. Ischemic injury was induced by 10 minutes of both common carotid artery ligation and hypotension (MAP < 50 mmHg). All rats were randomly divided into four groups: group I; control group; group II; ketamine 10 mg/kg was administered 10 minutes before injury; group III; propofol (1 mg/kg/min) was administered until EEG isoelectricity; and group IV; ketamine 10 mg/kg and propofol 1 mg/kg/min was administered. The Rectal temperature was maintained at 38oC. After forebrain ischemia, neurologic scores were estimated at 1 hr, 2 hrs, 1 day and 2 days after recovery. The brain was removed 3 days after and stained with H-E stain. RESULTS: Neurologic and histologic scores of group II, III, IV were significantly lower than that of group I. However, there were no significant difference between group II, III and IV. CONCLUSIONS: Ketamine and propofol have neuroprotective effects in transient forebrain ischemia in rats. However, the combination of propofol and ketamine did not show any synergistic or additive effects.

The Two Step Fiberoptic Approach in the Management of a Difficult Pediatric Airway due to a Vallecular Cyst / 대한마취과학회지

A 6-yr-old male weighing 20 kg with the diagnosis of a large vallecular cyst in the oropharynx was scheduled for surgical excision. After a slight loss of consciousness following an IV injection of ketamine 10 mg while maintaining spontaneous respiration, 4% lidocaine was sprayed into the right nostril. An uncuffed 4 mm OD wire-reinforced endotracheal tube was advanced through the right nostril and positioned in the nasopharynx. An ultrathin 60 cm Olympus LF-P fiberoptic bronchoscope (OD: 2.2 mm) was threaded and the vocal cords and surrounding structures were identified as intact. The endotracheal tube and fiberscope were withdrawn. Ketamine 10 mg was injected intravenously again. Following direct insertion of an Olympus fiberoptic bronchoscope (OD: 3.8 mm) through the right nostril without tube placement and visualization of the vocal cords, topical anesthesia of the larynx was achieved by spraying 1 ml 2% lidocaine through the biopsy channel. Thirty seconds later, it was passed into the trachea and 1 ml 2% lidocaine was sprayed intratracheally. The bronchoscope was withdrawn. The 4 mm uncuffed wire-reinforced tube was passed again through the right nostril and an ultrathin fiberoptic bronchoscope (OD: 2.2 mm) was threaded over the tube, and passed smoothly without resistance. There was neither laryngeal spasm nor cough. Anesthesia was maintained with enflurane 2.0 vol%, N2O (1.5 L/min) and O2 (1.5 L/min). The mass was successfully excised and extubated without compromise. The patient was uneventfully discharged the next day.

Patient-controlled Sedation and Analgesia in Patients Undergoing Cataract Surgery / 대한마취과학회지

BACKGROUND: Patient-controlled sedation with propofol has been shown to provide safe and effective sedation for patients undergoing surgery under local anesthesia. The purpose of this study was to evaluate the efficacy of patient-controlled sedation and analgesia with propofol and fentanyl in 17 patients undergoing cataract surgery. METHODS: An admixture of 400 mg of propofol with 100microgram of fentanyl (42 ml) was loaded into a patient-controlled analgesia pump and administered at a rate of 10 ml/hr. The lock-out time was 1 minute and the bolus dose was 1 ml. At the end of surgery, pain relief, anxiety relief and the satisfaction score were recorded on a patient questionnaire with a 1 to 10 scale. RESULTS: The sedation level varied from patient to patient and there was no incidence of oversedation. Most patients were satisfied with this anxiety and pain relieving technique (more than a score of 8). Blood pressure and arterial oxygen saturation showed minimal changes and remained within normal ranges. There were no complications except complaints of pain at infusion sites from 3 patients. CONCLUSIONS: Patient-controlled sedation and analgesia is a safe and satisfactory method for most patients undergoing cataract surgery for relieving pain and anxiety.

Changes in Bispectral Index during Coinduction with Intravenous Anesthetics Using Synergistic Interaction / 대한마취과학회지

BACKGROUND: Coinduction according to a hypnotic synergistic effect of intravenous anesthetics has an advantage of reducing hemodynamic change, induction dose and side effects of each drug. Meanwhile, the bispectral index has been used to monitor objective measurement of the hypnotic effect of intravenous anesthetics. The aim of this study was to evaluate the changes in the bispectral index during coinduction with two intravenous anesthetics that were known to have synergistic interactions. METHODS: Sixty ASA I or II adult patients undergoing elective surgery were assigned to one of three groups according to induction methods: group 1, thiopental + propofol; group 2, thiopental + midazolam; group 3, midazolam propofol. Anesthesia induction was performed by injecting half of a hypnotic ED50 dose of both drug according to the known time to peak effect. For example, in group 1, propofol was injected first, and then thiopental 1 min. later. The Bispectral index, vital signs, and SpO2 were checked every minute for 5 minutes after injection of a drug. RESULTS: Each group showed the lowest point of the BIS at time to peak effect, but the reduction of the BIS for each group showed no regular pattern between time and amount of degree compared to the lowest BIS of the two drugs when they were used alone. CONCLUSIONS: The BIS has limitations in expressing a synergistic interaction phenomenon when anesthesia induction with two intravenous anesthetics that have a synergistic interaction.

Protective Effect of Etomidate on Kainic Acid-induced Neurotoxicity in Rat Hippocampus / 대한마취과학회지

BACKGROUND: The present investigation was undertaken to evaluate the neuroprotective effect of etomidate against kainic acid (KA) induced neurotoxicity in rats by using the immunoreactivity of heat shock protein-70 (HSP-70) and the acid-fuchsin stain. METHODS: Administration of etomidate (20 mg/kg, I.P.) was performed in sequence; first being just one hour after a KA (10 mg/kg, I.P.) injection, then three more times at one hour intervals. Neuronal damages in the hippocampus were evaluated by using the acid-fuchsin stain to detect cell death and HSP-70 induction as an index of cell injury at 24 h after the administration of KA. RESULTS: HSP-70 induction and acid fuchsin positive neurons were increased in the CA1 and CA3 regions of the hippocampus after a KA injection but significantly decreased by an injection of etomidate (P < 0.01). CONCLUSIONS: These results suggest that the etomidate has a potential effect on the protection of neurons against KA-induced neurotoxicity.

Comparison of Poloxamer-407 to Soybean Oil as an Emulsifying Agent for Propofol: Histamine Release and Plasma Lipid Levels / 대한마취과학회지

BACKGROUND: To reduce side effects (hyperlipidemia, pain on injection, etc.) of the present formation of propofol, many attempts to change the emulsifying agent for propofol have been tried. This study was designed to examine the poloxamer-407 as an emulsifying agent for propofol compared to soybean oil regarding histamine release and plasma lipid levels. METHODS: Twelve Beagle dogs weighing 12 - 16 kg were randomly assigned to one of two groups according to the formulation of propofol. Group 1 received Diprivan propofol 1% (AstraZeneca Co. UK), and group 2 received poloxamer-407 formulated propofol by a continuous intravenous infusion at 30 mg/kg/h for 3 hours. Three, 6, 9 and 12 hours after discontinuing the propofol infusion, venous blood samples from the cranial tibial vein were analysed by an ELISA kit for the histamine level. Also, blood lipid levels were checked 3 hours after the infusion and blood propofol concentration were checked every hour during the infusion. RESULTS: Group 2 showed significantly less histamine release than group 1 at 3, 6 and 9 hours after the infusion (P < 0.05). In the plasma lipid study, there was no difference in high-density lipoprotein (HDL) between the two groups, but triglyceride and cholesterol were significantly higher in group 2 (P < 0.05). There was no difference in propofol concentrations between the two groups. CONCLUSIONS: Poloxamer-407 as an emulsifying agent for propofol showed no advantage compared to a present formulation regarding hyperlipidemia, and even decreased the histamine level.

Monitoring of Anesthetic Depth by BIS & Anemon Monitor / 대한마취과학회지

BACKGROUND: Monitoring of "Depth of anesthesia" is an ongoing problem in anaesthesia. In this study, the author has compared the bispectral index (BIS) and Anemon monitor for monitoring depth of anesthesia in propofol or isoflurane anesthesia. METHODS: Anemon-1 and BIS index were obtained from 24 patients (ASA I, II) during general anesthesia with propofol or isoflurane. For patients in the propofol group, anesthesia was induced with fentanyl 100ng followed by propofol 2 mg/Kg. For patients in the isoflurane group, anesthesia was induced with thiopental 5 mg/Kg. The author observed changes of these values at 5 major times: before induction, during induction, after induction, at sKin incision, before extubation, after extubation. RESULTS: The anemon index showed a significant increase during induction (propofol group: 86.9 +/- 26.4, isoflurane group: 106.0 +/- 18.6) and at sKin incision (propofol group: 89.9 +/- 22.7, isoflurane group: 92.0 +/- 23.1), but this did not correlate with the level of consciousness. The BIS index showed a significant decrease in the score after induction (propofol group: 55.0 +/- 9.6, isoflurane group: 61.0 +/- 17.2), but no response to surgical stimuli. CONCLUSIONS: BIS had a good correlation with level of consciousness. The Anemon-1 index was recognized to reflect invasive stimulus. As the BIS and Anemon-1 had no correlation, it was not possible to assume changes of each index from the other. Both the anemon-1 index and BIS are useful to monitor the anesthesia level during surgery.

Preventive Effect of Lidocaine Pretreatment and Tourniquet Use on Propofol Injection Pain / 대한마취과학회지

BACKGROUND: Pain on injection of propofol is a common problem, the cause of which remains unKnown. We evaluated the optimum time of a tourniquet with intravenous lidocaine, to decrease the intensity of pain during intravenous propofol injection. METHODS: In 72 patients undergoing general anesthesia, we subdivided all patients into 4 groups. Patients in group 1 (n = 18) received propofol only (1 mg/Kg IV) without a tourniquet, patients in group 2 (n = 18) received 1% lidocaine 20 mg IV with an upper arm tourniquet inflated to 50 mmHg applied for 1 minute followed by propofol (1 mg/Kg IV). We applied a tourniquet to patients in group 3 (n = 18) and 4 (n = 18) for 3 minutes and 5 minutes respectively. The intensity of pain along the forearm was classified in 4 degrees (none, mild, moderate, severe) by the patients and the observer simultaneously. The mean arterial pressure and heart rate were recorded before injection and at the time when the patient complained of pain. RESULTS: All groups were similar in age, sex, weight and height. The group with the tourniquet applied for 5 minutes followed by a lidocaine injection showed the lowest intensity of pain. However, between the group with 3 minutes and 5 minutes, the difference of the pain score was not statistically significant. CONCLUSIONS: We conclude that intravenous lidocaine administered after a tourniquet has been inflated to 50 mmHg for 3 minutes before propofol injection attenuates profoundly the pain associated with intravenous propofol injection.

Effects of Propofol on Hypoxic Pulmonary Vasoconstriction after Pretreatment with L-NAME and Glibenclamide in Isolated Rat Lungs / 대한마취과학회지

BACKGROUND: It is generally accepted that propofol does not inhibit hypoxic pulmonary vasoconstriction (HPV). However, because the previous studies for the effects of propofol on HPV were established in vivo, the effects of physiologic variables could not be ruled out. Therefore, we investigated the effects of various concentrations of propofol on HPV at isolated rat lungs and the relationship of these effects of propofol on HPV and endothelium-derived relaxing factor (EDRF) and an ATP-dependent K+ channel which were candidates as the mechanism of HPV. METHODS: In 30 isolated rat lungs, after three hypoxic challenges for 5 minutes, we administered saline in the control group, N(G)-nitro-L-arginine methyl ester (L-NAME) in the L group and glibenclamide in the G group followed by three hypoxic challenges for 5 minutes. In addition, we studied the effects of various concentrations of propofol on HPV in the three groups. RESULTS: L-NAME and glibenclamide did not alter baseline pulmonary arterial pressure but L-NAME significantly enhanced HPV. Clinical concentrations of propofol did not affect HPV and high concentrations of propofol inhibited HPV. The pretreatment of L-NAME and glibenclamide did not alter the inhibition of HPV even at high concentrations of propofol. CONCLUSIONS: The EDRF and ATP-dependent K+ channel did not largely contribute to baseline pulmonary arterial tone but EDRF might be released and downregulate HPV. Clinical concentrations of propofol did not inhibit HPV but high concentrations of propofol inhibited HPV. In addition, the mechanism of inhibition of HPV at high concentrations of propofol did not relate to the EDRF pathway and ATP-dependent K+ channel.

Research on Etomidate Complications Observed during Induction / 대한마취과학회지

BACKGROUND: The properties of etomidate include hemodynamic stability, minimal respiratory depression, cerebral protection, and rapid recovery. However, its drawbacks include temporary inhibition of steroid synthesis, pain on injection, thrombophlebitis, myoclonus, nausea and vomiting. This study was done to discover the incidence of complications which could be observed during induction and the relationship between these complications and the age, sex and weight of Koreans. METHODS: Induction was done by etomidate 0.3 mg/kg and vecuronium 0.1 mg/kg. Pain on injection and hiccup were checked as present or absent. Myoclonus was checked as absent, mild, or severe. RESULTS: The incidence of pain on injection, hiccup and myoclonus were 4%, 10%, and 40% (mild 28%, severe 12%) respectively. There was no association between pain on injection and hiccup or myoclonus. Hiccup and myoclonus had some association (Gamma 0.774). Logistic regression revealed that there was no association between pain on injection or hiccup, and sex, age or weight. Myoclonus had some association with age and weight. The occurrence of myoclonus could be estimated by the following equation. log[ Fj(x) / { 1 Fj(x) } ] = aj 0.061 age 0.019 weight j = 1, 2 As age or weight increased, the myoclonus was more likely to fall at the low end (i.e., absence). CONCLUSIONS: The incidences of the pain on injection, hiccup and myoclonus were 4%, 10% and 40% respectively. The hiccup and the myoclonus had some positive association. The occurrence of myoclonus decreased as age or weight increased.

Optimal Dosage of Propofol for Prevention of Increase in IOP during Rapid Sequence Induction with Endotracheal Intubation / 대한마취과학회지

BACKGROUND: Operations for patients with eye injuries frequently require rapid sequence induction of general anesthesia with succinylcholine (Sch), but Sch as well as endotracheal intubation produce increases in intraocular pressure (IOP). The purpose of this study was to examine whether the increase in dosage of propofol from a usual dosage would prevent the increase in IOP due to endotracheal intubation with Sch during a rapid sequence induction of general anesthesia. METHODS: Changes in IOP were measured in three groups of 15 patients each. The patients randomly received thiopental 5 mg/kg (group 1, n = 15), propofol 2.5 mg/kg (group 2, n = 15) or propofol 3.0 mg/kg (group 3, n = 15), followed by Sch 1.0 mg/kg and endotracheal intubation. IOP, systolic arterial pressure (SAP) and heart rate (HR) were measured before induction (baseline), just after intubation, 3 minutes and 10 minutes after intubation. RESULTS: IOP and SAP just after intubaton in groups 1 and 2 increased significantly from baseline, but did not increase significantly from baseline in group 3. IOP and SAP at 3 minutes after intubation in group 1 did not decrease significantly from baseline, but decreased significantly from baseline in groups 2 and 3. IOP and SAP at 10 minutes after intubaton in all groups decreased significantly from baseline. HR just after intubaton in groups 1 and 2 increased significantly from baseline, but did not increase significantly from baseline in group 3. HR at 3 minutes and 10 minutes after intubation in all groups did not change significantly from baseline. CONCLUSIONS: The authors concluded that propofol 3.0 mg/kg could prevent the increase in IOP, systolic arterial pressure and heart rate just after intubation during a rapid sequence induction of general anesthesia.