Effect of low-flow sevoflurane anesthesia on early postoperative renal function / 中华麻醉学杂志

Objective To evaluate the effect of low-flow sevoflurane anesthesia on the early postoperative renal function in patients.Methods Sixty patients of both sexes,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,aged 18-64 yr,scheduled for elective non-urological surgery with general anesthesia,with an expected surgical duration＞4 h,were divided into 2 groups (n =30 each) using a random number table method:middle-flow anesthesia group (group Ⅰ) and low-flow anesthesia group (group Ⅱ).Anesthesia was induced with Ⅳ midazolam,sufentanil,propofol and cisatracurium besylate.Mechanical ventilation was performed after tracheal intubation.Pure oxygen served as carrier,the fresh gas flow of oxygen was set at 4-5 L/min,sevoflurane was inhaled for 10-15 min,and then fresh gas flow was decreased to 2 L/min (group Ⅰ) and 0.5 L/min (group Ⅱ).End-tidal pressure of carbon dioxide was maintained at 35-45 mmHg.The end-tidal concentration of sevoflurane was set at 2.0％-2.4％,remifentanil and cisatracurium besylate were infused intravenously,and sufentanill or propofol was injected intermittently to maintain anesthesia.Bispectral index value was maintained at 40-60 during operation.Before anesthesia induction (T0),at 1,2,3 and 4 h after anesthesia induction (T1-4),immediately after operation (T5) and at 24 h after operation (T6),peripheral venous blood samples were collected for determination of serum fluoride ion concentrations.Peripheral venous blood samples and urine specimens were collected at T0,T5,T6,48 h after operation (T7) and 72 h after operation (T8) for determination of creatinine (Cr),blood urea nitrogen (BUN) and cystatin C (Cys C) and serum and urine β2-microglobulin (β2-MG) concentrations.Results Compared with the baseline at T0,serum fluoride ion concentrations were significantly increased at T1-6 in two groups,the serum Cys C concentration was increased at T5,and serum and urine β2-MG concentrations were increased at T5 and T6 in group Ⅰ,serum Cr and BUN concentrations and serum and urine β2-MG concentrations were increased at T5 and T6,and the serum Cys C concentration was increased at T5-T7 in group Ⅱ (P＜0.05).Compared with group Ⅰ,serum fluoride concentrations were significantly increased at T1-6,serum Cr and BUN concentrations and serum and urine β2-MG concentrations were increased at T5,and serum Cys C concentrations at T5-T7 and urine β2-MG concentrations at T5 and T6 were increased in group Ⅱ (P＜0.05).Conclusion Low-flow sevoflurane anesthesia produces no marked effect on early postoperative renal function in patients.

Auto-PEEP-like condition recognized by a sudden decrease in airway pressure during pressure controlled ventilation and low-flow anesthesia: A case report

During mechanical ventilation in the intensive care unit, auto-positive end-expiratory pressure (auto-PEEP) has been reported to occur in obstructive airway conditions aggravated by inappropriate ventilator settings. In this paper, we report a case of auto-PEEP-like problem during anesthesia, mainly caused by excessive sputum. After being positioned prone for spine surgery, the patient received pressure controlled ventilation at a low fresh gas flow rate. One hour after the start of surgery, sudden decreases in pressure and flow occurred. The typical maneuvers which could be performed by the anesthesiologists in the situations suggesting leakage within the breathing circuit consist of pressing the oxygen flush valve and manual hyperventilation for the initial evaluation. But from our experience in this case, we have learned that such maneuvers could cause unacceptable aggravation in the event of auto-PEEP. Also in this report, we discuss the difficulties in prediction based on the present knowledge of preoperative evaluation and the presumably best management policy regarding this type of auto-PEEP.

A suspicious case of malignant hyperthermia during general anesthesia with desflurane: A case report

Malignant hyperthermia (MH) is an inherited disorder of skeletal muscle manifested as a life threatening hypermetabolic crisis in susceptible individuals following exposure to commonly used inhaled anesthetics and depolarizing muscle relaxants. We experienced a suspicious case of MH in 34-year-old male during transfemoral cerebral angiography embolization under general anesthesia with desflurane. The episode emerged 15 minutes after induction of general anesthesia using propofol, rocuronium, remifentanil, desflurane. Desflurane is a recently developed inhaled anesthetics and there has been no case report of MH related with it in Korea. When we suspected episode, vigorous treatment was carried out, symptoms were resolved without dantrolene administration.

A comparison of the consumption of inhaled anesthetics according to fresh gas flow and anesthetic circuits / 대한마취과학회지

BACKGROUND: In the Korean National Health Insurance Corporation (KNHIC), payment for inhaled anesthetics are made according to the simulated dose and not the consumed dose. We compare the consumption of inhaled anesthetics according to fresh gas flow (FGF) and anesthetic circuits to compare the consumption of anesthetics and the guidelines for KNHIC payments. METHODS: 161 patients were randomized into six groups who received isoflurane using a closed circuit (group I-C), a semi-closed circuit with FGF 3 L/min (group I-3), or 4 L/min (group I-4), as for the sevoflurane group (group S-C, S-3, and S-4). Mean arterial pressure (MAP) and heart rate (HR) were maintained within +/- 20% of baseline. Minimum alveolar concentration (MAC) and consumption of inhaled anesthetics were recorded by a new anesthetic machine. RESULTS: There were no significant differences among the groups for MAP, HR, and MAC. During anesthesia maintenance, the mean consumption per 15 minutes of inhaled anesthetics was significantly lower in group I-C (1.0 +/- 0.3 ml) than in group I-3 (3.5 +/- 0.7 ml) and than group I-4 (4.9 +/- 0.9 ml) and similar to the sevoflurane groups (group S-C [1.3 +/- 0.4 ml] vs group S-3 [5.3 +/- 1.0 ml] vs group S-4 [6.9 +/- 1.3 ml], respectively; P < 0.05). CONCLUSIONS: In sevoflurane groups, inhaled anesthetics were consumed more than in isoflurane groups. The KNHIC payment guidelines were close to the actual consumption of inhaled anesthetics under using a semi-closed circuit with FGF 3 L/min in sevoflurane and FGF 4 L/min in isoflurane.

Effects of Fresh Gas Flow Rate on the Ratio of Expired to Inspired Anesthetic Concentration / 대한마취과학회지

BACKGROUND: One way to make rapid increase in alveolar anesthetic concentration includes using high fresh gas flow rates. Fresh gas flow rates should be increased to compensate the amount of uptake either. This study was performed to elucidate optimal fresh gas flow rates for rapid induction by comparison of changes of ratio of expired to inspired concentration. METHODS: The study population was composed of 107 patients undergoing thyroidectomy. Patients were randomly allocated to one of three groups who received desflurane or sevoflurane or isoflurane. Each group was randomly subdivided into three groups who received one of the fresh gas flow rate: 2, 5 or 10 L/min. Inspired anesthetic concentration (Fi) and expiratory anesthetic concentration (Fe), delivered concentration (FD) were recorded. RESULTS: With same fresh gas flow rates, there were significant differences between Fe/Fi of desflurane, sevoflurane, isoflurane. With same anesthetics, Fe/Fi of desflurane and sevoflurane were not influenced by fresh gas flow rates. But Fe/Fi of isoflurane at 2 L/min was significantly lower than 5 L/min and 10 L/min. Fi/FD of desflurane at 10 L/min did not differ from sevoflurane. At 2 L/min and 5 L/min, Fi/FD of desflurane was highest and then sevofluane, isoflurane in that order. CONCLUSIONS: Because rates of Fe/Fi of desflurane and sevoflurane were not influenced by fresh gas flow rates, 2 L/min of fresh gas flow rates could be selected. However, considering the wash-in time in circuit, optimal choice of fresh gas flow rate for desflurane and sevoflurane could be 5 L/min, that of isoflurane be 10 L/min.

The Effect of Fresh Gas Flow on Sevoflurane Concentrations during Emergence from Anesthesia / 대한마취과학회지

BACKGROUND: Fresh gas flow (FGF) influences the speeds of induction and emergence. In general, emergence protocol involves a stepwise decrease in the vaporizer setting at fixed FGF, which causes anesthetic overuse and contaminates operating rooms. This study was designed to compare the decreasing patterns of sevoflurane concentration among groups with a similar course but with different FGFs. METHODS: One hundred patients scheduled for elective operation were randomly allocated to 3 groups (FGF 1 L/min, FGF 2 L/min, FGF 4 L/min). After induction with thiopental sodium 5 mg/kg and rocuronium 0.9 mg/kg or vecuronium 0.1 mg/kg for tracheal intubation, anesthesia was maintained at 1.5% of end-tidal sevoflurane concentration at an inflow of 4 L/min (N2O 2 L/min and O2 2 L/min). Ten minutes prior to the estimated operation end point, we changed FGF and vaporizer settings to the following 3 different emergence protocols: changing inflow in the FGF 1 L/min group (N2O 0.5 L/min and O2 0.5 L/min) with turning vaporizer off, changing inflow in the FGF 2 L/min group (N2O 1 L/min and O2 1 L/min) with a two-step decrease in the vaporizer setting (1.0 vol% for first 5 minutes then with the vaporizer off), and maintaining the inflow in the FGF 4 L/min group with a three-step decrease in the vaporizer setting (1.0 vol% for first 5 minutes and 0.6 vol% for next 5 minutes then with the vaporizer off). In each group, inspiratory and end-tidal sevoflurane concentrations were recorded every minute for 16 minutes, while end-tidal CO2, mean arterial pressure, heart rate, and inspired oxygen fraction were recorded every two minutes for 16 minutes. RESULTS: End-tidal concentrations of sevoflurane were similar in the 3 groups at the 6th, and 7th minutes and continuously increasing differences in sevoflurane concentrations from the 11th to 16th minute were observed in the FGF 1 L/min and FGF 2 L/min groups versus the FGF 4 L/min group. The concentration curves for the FGF 1 L/min group showed a smoother decreasing pattern than those of the other groups. CONCLUSIONS: The use of low FGF without vaporizer during emergence reduces sevoflurane washout within anesthetic machines and the exhausting of anesthetics into operating rooms, and also offers an easier means of controlling anesthetic depth.

Low-flow Sevoflurane Anesthesia in Laparoscopic Cholecystectomy / 대한마취과학회지

BACKGROUND: Anesthetists participating in laparoscopic cholecystectomy (LC) with CO2 pneumoperitoneum has been cautious about adapting low-flow anesthesia (LFA). We investigated the efficacy of LFA compared to high-flow anesthesia (HFA) in LC. METHODS: Eighty patients undergoing LC were randomly assigned to one of the two groups (n = 40 each). In LFA, 1 L/min (50% O2 and N2O) of the total fresh gas flow (FGF) was used, whereas 4 L/min of the total FGF was used for HFA. Inspiratory and expiratory concentrations of O2, N2O, CO2, and sevoflurane were serially measured. Subjects were monitored for heart rate, blood pressure, and any procedural complications. RESULTS: None of the patients experienced any episodes of hypoxia, hypercapnia, and arrhythmia in both groups. The maximal end-tidal CO2 was 40.9 +/- 3.9 mmHg in LFA and 38.2 +/- 3.6 mmHg in HFA, respectively. The minimal O2 saturation was 98.3 +/- 0.6% in LFA and 98.8 +/- 0.7% in HFA, respectively. The inspiratory CO2 concentrations in both groups were all less than 1 mmHg throughout the anesthesia. CONCLUSIONS: In conclusion, LFA with sevoflurane using FGF of 1 L/min with setting of 50% O2 and N2O for LC could be performed safely without the risk of complications like hypercapnia, hypoxia, or arrhythmia compared to HFA.

Practical Choice and Knowledge of Korean Anesthesiologists for Fresh Gas Flow / 대한마취과학회지

BACKGROUND: The inhalational anesthesia is performed by the administration of inhalational agents and fresh gases. Low and high flows have their own advantages and disadvantages. In Korea, many anesthesiologists use more than 2 L/min of fresh gas flow (FGF). This study was performed to analyze the practice and knowledge of FGF use by Korean Anesthesiologists. METHODS: A questionaire was sent to 122 anesthesiologists (15 university hospitals and 16 general hospitals) who attended the 47th Annual Autumn Meeting of the Korean Society of Anesthesiology in 2002. The questionaire covered topics dealing with inhalational agents, FGF, and safety systems for inhalational anesthesia practice. RESULTS: The most preferred inhalational anesthetic was sevoflurane (65.6%). 88.5% of respondents used more than 2 L/min of FGF. The majority of the respondents, however, did not consider the reasons for using certain levels of FGF. Only 27% of hospitals had pulse oximetry, capnogram or muti-gas analysis, fail-safe device, and a scavenging system. CONCLUSIONS: Many anesthesiologists, especially trainees, failed to consider the use of FGF during inhalational anesthesia. Therefore, special consideration should be given to the training and education of trainees about the proper of FGF.

The Effect of Intratracheal Nebulized Lidocaine and Intravenous Lidocaine on the Cardiovascular Stimulating Response to Tracheal Intubation / 대한마취과학회지

BACKGROUND: Hypertension and tachycardia usually accompany laryngoscopy and tracheal intubation. Topical and intravenous lidocaine are used in an attempt to blunt these potentially adverse hemodynamic responses, but these effects of lidocaine are controversial. The purpose of this study is to evaluate whether intratracheal nebulized lidocaine and/or intravenous lidocaine attenuate circulatory stimulating response to tracheal intubation. METHODS: Sixty patients, ASA physical status I, scheduled elective surgery, were randomly assigned to receive a preintubation dose of either 5 mL of normal saline intravenously, 4 mL of 4% lidocaine by intratracheal nebulizer, 1.5 mg/kg of 2% lidocaine intravenously, or 4 mL of 4% lidocaine intratracheal nebulizer and 2% lidocaine of 1.5 mg/kg intravenouly. Induction of anesthesia was accomplished with 5 mg/kg of thiopental IV, and 1 mg/kg of succinylcholine was given. Laryngoscopy and intubation was performed, and anesthesia maintained with 2% enflurane in 50% nitrous oxide in oxygen. Blood pressure and heart rate were recorded at preinduction, after induction, and every minute until 5 min after intubation. RESULTS: Intratracheal nebulized lidocaine and/or intravenous lidocaine were effective in attenuating increases in systolic pressure with no detectable difference between them, and failed to attenuate increases in diastolic pressure and heart rate. And significant decrease in systolic pressure 3 min after intubation was detected in intratracheal and intravenous lidocaine group. CONCLUSIONS: These data suggest that intratracheal nebulized lidocaine or intravenous lidocaine is effective in attenuating increase in systolic pressure to tracheal intubation, but intratracheal and intravenous lidocaine has not synergistic effect.

The Use of the Maplson Type D in Febrile Pediatric Patients / 대한마취과학회지

The Mapleson type D is one of the non-rebreathing systems used in pediatric general anes- thesia. Because it doesnt have soda lime, the fresh gas tlow (FGF) must be adjusted to the patient's size, body temperature and the anesthetic technique to prevent CO2 retention. We have used the FGF of 2-3.5 L/min according to patient's body weight, whether or not the patient has a fever. So, we examined arterial blood gas analysis in 3 pediatric patients with fever. We suggest that if a patient has a fever, it is desirable to inmease FGF to 5 L/min to prevent CO2 accumulation or acidosis.

Tension Pneumothorax Developed during the Use of Jackson - Rees Modification System with Ayre's T-Piece / 대한마취과학회지

Pneumothorax was recognized as a potential hazard of mechanical ventilation during anesthesia. Because the gases used in anesthesia are delivered from cylinder and wall outlets at higher than atmospheric Pressure, the possibility of damage to the lung is over present. Alveolar rupture may occur when there is free transmission of high pressure to the alveoli during tracheal intubation at the start of anesthesia. We had a case of tension pneumothorax developed during the use of Jackson-Rees modification with Ayres T-piece for primary closure of laceration on right hand in 4 years old child under general anesthesia. The patient was presented of acute respiratory distress resulting from pneumothorax and subcutaneous emphysema just after tracheal intubation. The tension pneumothorax was noticed on chest X-ray. This complication was the result of undesirable alveolar ventilation with high fresh gas flow by accidental using of oxygen flush valve. With the prompt decision of diagnosis of tension pneumothorax and aggresive treatment, the patient recovered uneventfully and discharged 7 days later.

Effects of Six Heat and Miosture Exchange for Use during Endotracheal Anesthesia / 대한마취과학회지

Despite many theoretical advantages of humidification of anesthetic gas, the role and method of choice of humidification in anesthesia remains uncertain. With the recent introduction of disposable heat and moisture exchangers (HME), a paueity of information of the specific performance characteristics of various HMEs exists. Using an on-line humidity detector, based on the dry-wet bulb principle, with a fast response temperature sensor (0.l sec), I have reexamined the effectiveness in maintaining humidity and temperature of various commercially available HMEs in clinical settings, and the relationship of the effectiveness of the rate of fresh gas flow. Humid-Vent 2 demonstrated the best result that increased the inspired temperature from 22.78+/-0.2degrees C to 31.35+/-0.89degrees C (absolute humidity; 27.4+/-0.7mg H2O/L). Extreme low fresh gas flow(500ml/min) demonstrated low absolute humidity (18.87+/-1.28 mg H2O/L) that was lower than use of HME.

Effects of Six Heat and Miosture Exchange for Use during Endotracheal Anesthesia / 대한마취과학회지

Despite many theoretical advantages of humidification of anesthetic gas, the role and method of choice of humidification in anesthesia remains uncertain. With the recent introduction of disposable heat and moisture exchangers (HME), a paueity of information of the specific performance characteristics of various HMEs exists. Using an on-line humidity detector, based on the dry-wet bulb principle, with a fast response temperature sensor (0.l sec), I have reexamined the effectiveness in maintaining humidity and temperature of various commercially available HMEs in clinical settings, and the relationship of the effectiveness of the rate of fresh gas flow. Humid-Vent 2 demonstrated the best result that increased the inspired temperature from 22.78+/-0.2degrees C to 31.35+/-0.89degrees C (absolute humidity; 27.4+/-0.7mg H2O/L). Extreme low fresh gas flow(500ml/min) demonstrated low absolute humidity (18.87+/-1.28 mg H2O/L) that was lower than use of HME.