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PubMed1990

Respiratory diagnostic possibilities during closed circuit anesthesia.

An automatic feed back controlled totally closed circuit system (Physioflex) has been developed for quantitative practice of inhalation anesthesia and ventilation. In the circuit system the gas is moved unidirectionally around by a blower at 70 l/min. In the system four membrane chambers are integrated for ventilation. Besides end-expiratory feed back control of inhalation anesthetics, and inspiratory closed loop control of oxygen, the system offers on-line registration of flow, volume and respiratory pressures as well as a capnogram and oxygen consumption. Alveolar ventilation and static compliance can easily be derived. On-line registration of oxygen consumption has proven to be of value for determination of any impairment of tissue oxygen supply when the oxygen delivery has dropped to critical values. Obstruction of the upper or lower airways are immediately detected and differentiated. Disregulations of metabolism, e.g. in malignant hyperthermia, are seen in a pre-crisis phase (increase of oxygen consumption and of CO2 production), and therapy can be started extremely early and before a disastrous condition has developed. Registration of compliance is only one of the continuously available parameters that guarantee a better and adequate control of lung function (e.g. atalectasis is early detected). The newly developed sophisticated anesthesia device enlarges tremendously the monitoring and respiratory diagnostic possibilities of artificial ventilation, gives new insights in the (patho)physiology and detects disturbances of respiratory parameters and metabolism in an early stage.

Airway Resistance↗
PubMed2002

Prospective evaluation of anesthetic technique for anorectal surgery.

PURPOSE: Deep intravenous sedation plus local anesthesia for anorectal surgery in the prone position is used frequently at our institution, but is not widely accepted because of concerns regarding airway management. The purpose of this study was to prospectively evaluate the safety and efficacy of this anesthetic technique for anorectal surgery. METHODS: Data were collected prospectively on 413 consecutive patients (mean age, 47 years; mean weight, 80 kg) undergoing anorectal surgical procedures. RESULTS: Of the 389 patients who underwent anorectal procedures in the prone position, 260 (67 percent) received intravenous sedation plus local anesthesia, 125 (32 percent) received regional anesthesia (spinal or epidural), and 4 (1 percent) received general endotracheal anesthesia. Of the 24 patients who underwent anorectal procedures in the lithotomy position, 13 (54 percent) received intravenous sedation plus local anesthesia, 2 (8 percent) received regional anesthesia, 2 (8 percent) received general endotracheal anesthesia, and 7 (29 percent) received mask inhalational anesthesia. Forty-two adverse events attributable to the anesthetic occurred in 18 patients: nausea and vomiting (n = 17), transient hypotension, bradycardia, or arrhythmia (n = 8), transient hypoxia or hypoventilation (n = 7), urinary retention (n = 6), and severe patient discomfort (n = 2). These complications occurred in 4 percent (10/273) of patients receiving intravenous sedation plus local anesthesia and in 6 percent (8/127) of patients receiving regional anesthesia. Two of 260 patients (0.8 percent) receiving intravenous sedation plus local anesthesia in the prone position were rolled supine before completing the surgical procedure. Recovery time before discharge for patients treated on an ambulatory basis was significantly shorter for those patients undergoing intravenous sedation plus local anesthesia (79 +/- 34 minutes, n = 174) than for patients undergoing regional anesthesia (161 +/- 63 minutes, n = 45; P < 0.001, t-test). CONCLUSION: Intravenous sedation plus local anesthesia in the prone position is safe and effective for anorectal surgery and offers potential cost savings by decreasing recovery room time for outpatient procedures.

Adult↗
PubMed1995

Pharmacokinetics of intravenous ondansetron in healthy children undergoing ear, nose, and throat surgery.

BACKGROUND: To determine the pharmacokinetics of the 5-HT3 antagonist ondansetron in children, informed written consent was obtained from the parents of 21 healthy children aged from 3 to 12 years scheduled for ear, nose, and throat surgery. METHODS: The children were stratified according to age: 3 to 7 years and 7.1 to 12 years, and a single intravenous infusion of 2 or 4 mg ondansetron, respectively, was administered over 5 minutes before induction of anesthesia. After completion of the infusion, anesthesia was induced intravenously and maintained with inhalational anesthesia. Whole blood (3 ml) was obtained before administration of ondansetron, at completion of the infusion, at the beginning and end of surgery, and at 3, 4, 6, 8, 10, and 12 hours after start of the infusion. Pharmacokinetic variables were determined with use of standard noncompartmental techniques. RESULTS: Mean plasma clearance was 0.50 L.hr-1.kg-1 and 0.39 L.hr-1.kg-1, the mean volume of distribution at steady-state was 1.70 L.kg-1 and 1.61 L.kg-1, and the mean plasma terminal half-life was 2.6 hours and 3.1 hours for the 2 mg and 4 mg groups, respectively. On a body surface area basis, mean plasma clearance was 14.0 and 13.7 L.hr-1.m-2 and mean volume of distribution was 47.7 and 55.9 L.m-2 for the 2 and 4 mg groups, respectively. There were no serious adverse events attributable to ondansetron. CONCLUSIONS: These data indicate that the pharmacokinetics of ondansetron in children from 3 to 12 years old are predictable and similar to those in adults. The elimination half-life of ondansetron increases in parallel with age. However, clearance is constant when normalized to body surface area, but the volume of distribution increases over the age range studied.

Adenoidectomy↗
PubMed1994

Effects of ondansetron in the prevention of postoperative nausea and vomiting in children.

BACKGROUND: Postoperative nausea and vomiting (PONV) is a commonly observed adverse effect of general anesthesia. Recently, ondansetron, a new serotonin3 (5-hydroxytryptamine3) receptor antagonist was shown to be effective in the prophylaxis and prevention of chemotherapy-induced nausea and vomiting in children and adults as well as of PONV in adults. The aim of the current study was to evaluate the capacity of ondansetron to prevent PONV in pediatric patients. METHODS: Two hundred children (132 boys and 68 girls) 2-10 yr of age received general inhalational anesthesia for surgical procedures (the extremities; ear, nose, and throat; inguinal hernia and phimosis; and dentistry) of an expected duration of less than 90 min. This study was divided into two phases: prophylaxis and rescue treatment. For prophylaxis, patients were randomly assigned to two groups: one group received an intravenous injection of 0.1 mg/kg ondansetron, and the other group received a placebo before surgical incision under double-blind conditions. For rescue treatment, only placebo patients were included; as a rescue medication they received an intravenous injection of 0.1 mg/kg ondansetron or 0.02 mg/kg droperidol according to a prestudy randomization under double-blind conditions. Incidence and severity of PONV (PONV score 0 = no nausea and no retching; 1 = complaining of sickness and retching; 2 = vomiting one or two time in 30 min; 3 = vomiting more than two times in 30 min) was recorded over a 4-h period in the postanesthesia care unit. Within 72 h of the procedure, a follow-up nurse interviewed the parents for late-onset nausea in the children. RESULTS: With regard to prophylaxis, 10% of patients receiving ondansetron had PONV during the 4-h observation period versus 40% of those receiving placebo (P < 0.001). The incidence of vomiting alone (PONV score > or = 2) was 5% and 25%, respectively (P < 0.001). There were no significant differences between ondansetron and droperidol in the treatment of PONV. However, at the end of the 4-h period, ondansetron patients were less sedated than were patients who had received droperidol (P < 0.01). Interviews with parents could be performed for 143 of 200 children (76 ondansetron and 67 placebo). Twenty-four children (15 ondansetron and 9 placebo) showed late-onset PONV after the 4-h observation period but within 24 h of the procedure (19.7% vs. 13.4%; P not significant). CONCLUSIONS: Ondansetron is effective in the prevention of PONV in pediatric patients for the first 4 h after general anesthesia. Lower sedation scores with ondansetron compared with droperidol may be an advantage, especially in ambulatory surgery. However, the incidence of late-onset PONV (> 4-24 h) was not influenced by prophylactic treatment with one dose of ondansetron preoperatively.

Anesthesia, General↗
PubMedDate not supplied

Capnographic monitoring during anesthesia with controlled ventilation in the horse.

Forty-five horses were maintained on halothane or isoflurane anesthesia for at least 90 minutes and received positive pressure ventilation after the first 30 minutes of anesthesia. Parameters monitored included end-tidal partial pressure of carbon dioxide (ETPCO2), arterial blood pressure, and arterial blood gases and pH. There was a statistically significant correlation between end-tidal carbon dioxide and arterial partial pressure of carbon dioxide (PaCO2) for both halothane and isoflurane anesthesia. There was no significant correlation between end-tidal carbon dioxide and either body weight or systolic blood pressure. No statistically significant difference was found in arterial to end-tidal carbon dioxide difference nor in alveolar dead space because of time or positioning over anesthetic periods of up to 3 hours. It is concluded that end-tidal carbon dioxide monitoring is a satisfactory measure of changes in respiratory acid-base balance with inhalation anesthesia in horses when ventilation is controlled.

Anesthesia, Inhalation↗
PubMed2000

Sevoflurane anesthesia in a myasthenic patient undergoing transsternal thymectomy.

Myasthenia gravis (MG) is an autoimmune disease resulting from the production of antibodies against the acetylcholine receptors of the neuromuscular synapse. The thymus gland is involved in the autosensitization process, and there is a consensus that all adults with generalized MG should have a thymectomy. Removal of a much thymic tissue as possible via the transsternal approach in the logic goal of thymectomy in the treatment of MG. Because of the unpredictable response to succinylcholine and the marked sensitivity to nondepolarizing muscle relaxants in the MG patients, some anesthesiologists avoid the use of muscle relaxants in the myasthenic patients, and depend on deep inhalation anesthesia, such as halothane, isoflurane or sevoflurane. In the present report, we used sevoflurane 4%, without supplementation by muscle relaxants, for the induction and maintenance of anesthesia in a MG patient undergoing transsternal thymectomy. The report reviews the anesthetic technique, and describes the electromyographic (EMG) changes following sevoflurane.

Adult↗
PubMed1980

Limb blood flow. The influence of temperature during halothane-nitrous oxide anesthesia.

Twenty adult patients were examined before anesthesia, during anesthesia, and at the end of surgery to determine the influence of body cooling on limb blood flow during prolonged halothane-nitrous oxide anesthesia. Measurements included temperature, mean arterial pressure, and leg blood flow. Cooling was prevented in ten patients by warmed anesthetic gases. The mean tympanic temperature at end of surgery was 37 degrees C for the warmed (W) and 35 degrees C for the unwarmed (UW) patients, a significant difference. The mean value for leg blood flow was significantly decreased in the UW patients (W = 5.0 vs UW = 3.1 mL/100 cc of tissue/min). These results indicate that body cooling during prolonged inhalation anesthesia was associated with a reduced limb blood flow. Therefore, pulmonary warming may be of potential benefit under similar conditions to help prevent intraoperative vascular complications.

Abdomen↗
PubMed2006

Comparison of minimum alveolar concentration between intravenous isoflurane lipid emulsion and inhaled isoflurane in dogs.

BACKGROUND: As in inhaled isoflurane anesthesia, when isoflurane lipid emulsion (ILE; 8%, vol/vol) is intravenously administered, the primary elimination route is through the lungs. This study was designed to determine the minimum alveolar concentration (MAC) and the time course of washout of isoflurane for intravenously infused ILE by monitoring end-tidal isoflurane concentration. METHODS: Twelve healthy adult mongrel dogs were assigned randomly to an intravenous anesthesia group with 8% ILE or to an inhalation anesthesia group with isoflurane vapor. An up-and-down method and stimulation of tail clamping were used to determine MAC of 8% ILE by intravenous injection in the intravenous anesthesia group and MAC by the inhaled approach in the inhalation anesthesia group, respectively. Isoflurane concentration and partial pressure in end-tidal gas, femoral arterial blood, and jugular venous blood were measured simultaneously just before each tail clamping and during washout. RESULTS: The induction time in the intravenous anesthesia group (105 +/- 24 s) was shorter than that in the inhalation anesthesia group (378 +/- 102 s; P < 0.01). MAC of 8% ILE by intravenous injection (1.12 +/- 0.18%) was significantly less than MAC by the inhaled approach (1.38 +/- 0.16%; P < 0.05). No significant difference was found between the two groups in the time course of washout of isoflurane. CONCLUSION: The MAC of intravenous anesthesia with 8% ILE was less than that of inhalation anesthesia with isoflurane vapor in dogs.

Administration, Inhalation↗
PubMedDate not supplied

Cardiovascular effects of isoflurane and halothane during controlled ventilation in older patients.

Isoflurane or halothane was administered at two different inspired concentrations to 21 surgical patients whose average age was 62 years. Most were in physical status (ASA) II or III. Patients were premedicated with diazepam and atropine, anesthesia was induced with thiopental, and tracheal intubation was facilitated with succinylcholine. Respiration was controlled manually or with a ventilator. Anesthesia was maintained with 60 percent N2O and halothane 1 percent, then 0.5 percent, or with N2O-isoflurane 1.2 percent, then 0.6 percent in O2. Variations in the cardiovascular responses among patients given the same anesthetic were as great as the variation in responses between anesthetics. Both produced similar decreases in arterial pressure, cardiac output, and stroke volume. Changes in pulse rate were minimal, and total peripheral resistance changes quite variable, for both drugs. Both halothane and isoflurane appear satisfactory for inhalation anesthesia in the elderly.

Age Factors↗
PubMed1998

Air contamination of a closed anesthesia circuit.

Closed-circuit anesthesia (CCA) has certain advantages such as decreased cost, decreased anesthetic gas pollution, improved inhalational gas humidity and temperature in comparison to conventional inhalational anesthesia using a high fresh gas flow, i.e. more than 2 L x min(-1), with a semi-closed breathing circuit. The main disadvantage of CCA is the possibility of hypoxic anesthetic gas delivery. This potentially lethal situation is caused by an insufficient oxygen flow rate for the body metabolism or by the accumulation of inactive gas, usually nitrogen, within the breathing circuit in spite of a sufficient oxygen concentration in the fresh gas supply to the breathing circuit. In the latter case, the accumulation of inactive gas may also lead an increased risk of awareness because of its dilution effect on the concentrations of inhalational anesthetics. We herein present a case of air contamination of the breathing circuit through a sampling line of an anesthetic gas monitor. The air caused a decrease in the oxygen concentration during closed circuit anesthesia.

Air↗
PubMed1998

Inhibition of physiologic stress responses by regional nerve block during orthognathic surgery under hypotensive anesthesia.

OBJECTIVE: The purpose of this study was to investigate the inhibitory effects of nerve block on stress responses during orthognathic surgery involving general anesthesia with induced hypotension. STUDY DESIGN: Fourteen patients (ASA-1) undergoing Le Fort 1 osteotomy and sagittal splitting mandibular osteotomy were divided into 2 groups: a block group (with maxillary and mandibular nerve blocks; n = 7) and a non-block group (without nerve blocks; n = 7). Anesthesia was maintained with N2O-O2 and isoflurane (block group, 0.8%; non-block group, 1.2%). Adenosine triphosphate was administered for induced hypotension. Observed variables included hemodynamic parameters and fluctuations and adenosine triphosphate dose. Plasma norepinephrine concentrations and blood gases were observed in the block group. RESULTS: More stable hemodynamics, with a lower adenosine triphosphate dose as well as negligible changes in norepinephrine concentrations and blood gases, were obtained in the block group. CONCLUSIONS: The stress responses were inhibited by nerve blocks combined with low-concentration inhalation anesthesia during adenosine triphosphate-induced hypotension. The adenosine triphosphate requirement was reduced under stable hemodynamics achieved with nerve blocks.

Adenosine Triphosphate↗
PubMed2001

[Anesthetic experience of emergency coronary artery bypass graft operation in a patient with cardioamyloidosis].

A 76-year-old woman with acute myocardial infarction underwent an emergency coronary artery bypass graft operation. She developed cardiac failure and sick sinus syndrome before the surgery because she was with cardioamyloidosis. Therefore, intra-aortic balloon pumping and the pacemaker were used to maintain the hemodynamics prior to the operation. Anesthesia was induced with midazolam 5 mg, morphine 30 mg and pancuronium 5 mg, and maintained with 0.3-0.5% isoflurane in 50% nitrous oxide and 50% oxygen. Morphine 10 mg was also injected during the surgery, and the total dose of morphine 40 mg was administered. The pacemaker at 80 bpm was inserted and mexiletine 0.5 mg.kg-1.h-1 was given to prevent ventricular arrhythmias at weaning from cardio-pulmonary bypass. The surgical operation was successfully performed and the postoperative course was uneventful. A combination of light inhalation anesthesia with narcotics may be a choice for anesthetic management of patients with cardioamyloidosis as this method has less influence on hemodynamics.

Aged↗
PubMed1992

The case for maintenance of general anesthesia with an inhalational agent.

Control of anesthetic depth is the primary advantage of general anesthesia with inhalational anesthetics as opposed to injectable agents. In addition, inhalational anesthetics provide good intraoperative stress reduction, adequate muscle relaxation, and an elimination pathway (lungs) independent of liver and kidney function. There is little postoperative respiratory depression and no rebound effect, which is sometimes seen with injectable anesthetics. The incidence of anesthetic-related toxicity is rare and is not considered a problem.

Anesthesia, Inhalation↗
PubMedDate not supplied

[Comparative study of the behavior of isoflurane and halothane in pediatric anesthesia].

This study involves 60 patients below the age of 14 years who were subjected to short duration surgical procedures under inhalation anesthesia with halothane and isoflurane at equivalent CAM in 50% protoxide. The objectives of the study were: a) to establish which of the two inhalational agents produced the more rapid anesthetic induction; b) to determine which exerted the more marked potentiation of the neuromuscular blockade induced by succinylcholine, and c) to compare the anesthetic quality during the induction and recovery periods of both halogenated agents. Induction was more rapid after halothane (mean induction time of 2.91 +/- 0.97 min) than after isoflurane (mean induction time of 6.24 +/- 2.88 min; p less than 0.001). Potentiation of succinylcholine induced neuromuscular blockade was greater after isoflurane than after halothane: the mean time of apnea was 4.56 +/- 1.82 min for isoflurane and 3.41 +/- 1.63 min for halothane (p less than 0.05). Undesirable effects were larger in patients treated with isoflurane than in patients anesthetized with halothane (mean score: 12.60 +/- 3.53 points vs 14.41 +/- 2.33 points; p less than 0.001). The analysis of anesthetic quality during the recovery period gave a mean punctuation of 16.62 +/- 2.21 to patients treated with halothane, whereas patients anesthetized with isoflurane showed a lower score of 14.25 +/- 1.99 points (p less than 0.001). The higher scores corresponded to the most well tolerated anesthetic induction and recovery. The highest attainable score in this study was 18.

Adolescent↗
PubMed1993

[The intracuff pressure changes in N2O gas-barrier cuff made of a special material].

During inhalation anesthesia using N2O, the intracuff pressure has been reported to increase due to diffusion of N2O into the cuff. The excessive intracuff pressure may produce ischemia of the tracheal mucosa. In this study, the changes in the intracuff pressure of endotracheal tube with a cuff made of a material with high N2O gas-barrier properties were compared with those of the normal endotracheal tubes. Forty adult patients (16 males and 24 females) were anesthetized with oxygen 2 l.min-1, N2O 4 l.min-1 and isoflurane under controlled ventilation and they were divided into the following three groups according to the type of the endotracheal tube used: the tube with a standard cuff made by PORTEX Co. Ltd; the tube with a profile cuff (high volume cuff) made by PORTEX Co. Ltd; the tube with gas-barrier cuff made by TERUMO Co. Ltd. The changes of each intracuff pressure were recorded continuously for 180 minutes after cuff inflation. A marked increase of the pressure was observed after inhalation of N2O in standard and profile cuff groups. In gas-barrier cuff group, there was a tendency of increasing cuff pressure without a statistically significant difference. The present study suggests that the use of a cuff with a material of high N2O gas-barrier properties would be effective to prevent increased intracuff pressure by N2O diffusion, and this would be especially useful during long anesthesia and hypotensive anesthesia.

Adult↗