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.

The Clinical Experience of Propofol-Alfentanil Anesthesia Using Computer Assisted Continuous Infusion / 대한마취과학회지

The short duration and fast onset of action of alfentanil underpins its suitability for use in anesthetic techniques. In these case studies, we have assessed the efficacy, safety and feasibility of alfentanil as an analgesic adjuvant of propofol based general anesthesia. Propofol was titrated to Keep the bispectral index in the 40 50 range. Alfentanil was infused at the effect site concentration of 80 or 160 ng/ml using a computer assisted continuous infusion. Two patients in this pilot study showed stable hemodynamics, smooth emergence and satisfactory postoperative pain control with additional analgesics in PACU.

A Successful Tracheostomy under General Anesthesia with Blind Intubation via ILMA in a Sitting Position / 대한마취과학회지

The intubating laryngeal masK airway is a newly available device designed to allow for blind endotracheal intubation and treatment of patients with difficult airways. Emergency tracheostomies are required for oropharyngeal, hypopharyngeal, and laryngeal tumors acutely obstructing the airway. Patients with an airway obstructive tumor maintain their airway by a very active inspiratory effort in a sitting position. In these patients, it may be impossible to position them for a tracheostomy with shoulder extension. We report a case where a patient was tracheostomized successfully under general anesthesia with blind intubation via ILMA insertion in a sitting position.

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.

The Negative Effects of Patient Controlled Sedation Using Midazolam for Cataract Surgery under Retrobulbar Block / 대한마취과학회지

BACKGROUND: Careful sedation is needed for cataract operation that requires absolute cooperation of elderly patients. Patient-controlled sedation (PCS) allows patients themselves change the dose of sedatives along with their need. The goal of this study was to find out midazolam PCS could achieve an adequate sedation without complications during cataract surgery and the differences of patients who needed PCS or not. METHODS: PCS with midazolam was applied to 33 patients undergoing cataract surgery using retrobulbar block (midazolam, bolus 0.5 mg, lock out interval 3 minutes, 1 hour limit 4.5 mg). PCS pump was given to patients 30 min before retrobular block. And patients themselves decided to use or not to use PCS after full explanation on PCS. Sedation score, visual analogue scale of anxiety, cognitive function, side effects and satisfaction of PCS were measured. RESULTS: PCS users were 22 (67%). Mean midazolam dosage of PCS users was 2.03 mg. Preoperative and intraoperative anxiety score were 40.2 mm and 13.0 mm in PCS users and 15.5 mm and 21.8 mm in non-users. The difference between PCS users and non-users was only preoperative anxiety levels. Age, sex, weight, education levels, previous cataract surgery, preoperative desired sedation levels did not influence on the PCS using. There was positive correlation of midazolam doses with only preoperative anxiety levels. 76% of surgeons and 85% of patients were satisfied with PCS but 7 patients showed involuntary movement. Cognitive functions and discharge time were not influenced by PCS. CONCLUSIONS: Although patients and surgeons were satisfied with the midazolam PCS, 33% of patients did not need PCS and deep sedation with involuntary movement that could bring surgical complications was resulted in some PCS users. We conclude that PCS for cataract surgery would be safer when it is administered under careful supervision of anesthesiologist.

Effects of Flow Rate and Dilution during Anesthesia Induction with Propofol / 대한마취과학회지

BACKGROUND: The Pharmacokinetic parameter and the degree of dilution can have an effect on induction time and vital signs during general anesthesia with propofol. Induction time, induction dose and vital signs according to various flow rates and the degrees of dilution during anesthesia induction with propofol were studied. METHODS: After institutional review board approval, and informed consent, One hundred and eighty ASA I or II adult patients undergoing elective surgery were assigned to one of four groups according to their degree of dilution. One group was undiluted and another 3 groups were diluted with 5% D/W (1:1, 1:2, 1:3). Each group was divided into 3 subgroups according to their flow rates of 25, 50, 100 mg/kg/hr. No premedication was given. With routine monitoring including radial arterial cannulation, propofol was infused using a syringe or infusion pump (Becton Dickinson pump, Franklin Lakes New Jersey, USA) in the previously designed manner. Induction time defined as loss of eyelash reflex, induction dose, and vital signs were checked. RESULTS: The faster the flow rate and the more diluted a drug, the shorter the induction time. The faster the flow rate and the less diluted a drug, the greater the induction dose. The more diluted a drug, the less the decrease in systolic blood pressure. Flow rate has little influenced decreasing systolic blood pressure. CONCLUSIONS: We concluded that it is reasonable to reduce flow rate and dilute propofol when the hemodynamic changes of the patient should be minimal during propofol based sedation/anesthesia.

Inhibitory Effects of Propofol Mixed with Lidocaine on Fentanyl Induced Cough Reflex / 대한마취과학회지

BACKGROUND: Propofol and lidocaine have been purported to attenuate bronchoconstriction induced by fentanyl administration during induction of anesthesia. The purpose of the present study was to study the synergic bronchodilation effect of propofol mixed with lidocaine. METHODS: Two hundred and thirty four patients were randomly allocated to five groups: Group 1 (n = 60, normal saline 0.25 ml/kg followed by fentanyl 3ng/kg), Group 2 (n = 30, propofol 2 mg/kg mixed with normal saline 0.05 ml/kg followed by normal saline 0.06 ml/kg), Group 3 (n = 50, propofol 2 mg/kg mixed with normal saline 0.05 ml/kg followed by fentanyl 3ng/kg), Group 4 (n = 33, propofol 2 mg/kg mixed with lidocaine 1 mg/kg followed by normal saline 0.06 ml/kg) and Group 5 (n = 61, propofol 2 mg/kg mixed with lidocaine 1 mg/kg followed by fentanyl 3ng/kg). All patients were injected with fentanyl or normal saline two minutes after administration of propofol premixed with lidocaine or normal saline, respectively. We checked the cough reflex, injection pain, oxygen desaturation and chest wall rigidity. RESULTS: There was a significant difference in the incidence of cough reflex between group 1 and 3 or 5. The incidience of group 5 was significantly lower than in group 3. CONCLUSIONS: This study suggests that a propofol-lidocaine mixture should be considered when patients require bronchodilation during induction of anesthesia.

Relaxant Effects of Thiopental, Ketamine, and Propofol on Isolated Rat Tracheal smooth Muscle / 대한마취과학회지

BACKGROUND: Intravenous anesthetics may modify airway responsiveness. The author investigated the relaxant effect of thiopental, ketamine, and propofol on isolated rat tracheal smooth muscles. METHODS: The trachea of the rat was dissected and cut into 3-mm rings. The rings were mounted in a water-jacked organ bath filled with Krebs solution aerated with 95% O2 and 5% CO2 at 37degreesC. Thiopental, ketamine, and propofol were given randomly to each ring preconstricted with EC50 of acetylcholine from 10(-6) to 10(-3) M. The relaxation response was the tension during anesthetic equilibration, expressed as a percentage of the tension from EC50 of acetylcholine. RESULTS: Thiopental and propofol (10(-5) to 10(-3) M) relaxed acetylcholine-induced contractions in a dose dependent manner (P < 0.05). Ketamine in doses of 10(-5) and 10(-4) M constricted acetylcholine-induced contractions by 3.2% and 16.5% respectively (P < 0.05). But ketamine in a dose of 10(-3) relaxed acetylcholine-induced contractions by 76.4% (P < 0.05). The relaxation of tracheal smooth muscles was greatest in thiopental, and was least in ketamine (P < 0.05). CONCLUSIONS: All three intravenous anesthetics have an excellent relaxation of tracheal smooth muscles in rats, except in doses of 10(-5) and 10(-4) M of ketamine.

Evaluation of Marsh's Pharmacokinetic Parameter Set for Target Controlled Infusion of Propofol in Korean / 대한마취과학회지

BACKGROUND: Marsh's pharmacokinetic parameter set is the most widely used parameter for target controlled infusion for propofol. However, Marsh's model was derived from a European population, and it is uncertain whether this model is accurate for Koreans. METHODS: Thirty ASA 1 or 2 adult patients undergoing orthopedic surgery participated in this study. Atropine 0.5 mg was injected for premedication. Anesthesia was induced by a TCI of propofol with a target concentration of 6 microgram/ml and maintained around 3 - 5 microgram/ml according to the bispectral index (35 - 45). In the middle of surgery, target concentrations were increased to 6 microgram/ml and maintained until effect site concentration was the same concentration. Three minutes after equilibration, 3 ml of blood was drawn from the radial artery and contralateral antecubital cephalic vein for measuring blood concentration using HPLC. Target concentrations were gradually decreased at the interval of 1 microgram/ml until the end of surgery and a blood sample was drawn as described in the method. A sample for every 1 microgram/ml was collected in the recovery room. Performance error of the predicted concentration of blood was calculated. RESULTS: The performance error was -12.86 - 16.55% for 1 - 6 microgram/ml of predicted concentration. Measured concentrations were higher than predicted at higher concentrations, but lower at lower concentrations. Measured cardiac output and arteriovenous concentration differences at 1 - 6 microgram/ml showed no difference. CONCLUSIONS: Marsh's pharmacokinetic model was accurate for propofol TCI in Koreans in terms of relatively low performance error (< 20%) in the concentration range of 1 - 6 microgram/ml.