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PubMed1985

The effect of Fluosol-DA on induction of inhalation anesthesia.

The liquid/gas partition coefficients of three inhalation anesthetics in Fluosol-DA 20% (Fluosol), a perfluorocarbon blood substitute, were determined in vitro. The high values found (6.68 for halothane, 7.54 for enflurane, and 7.20 for isoflurane) suggested that induction with these agents would be prolonged in patients treated with Fluosol. Induction of isoflurane anesthesia (as a representative agent) at constant inspired concentration was studied in five mongrel dogs before and after replacement of about 25% of each animal's blood volume with Fluosol. Inspired and end-tidal isoflurane and carbon dioxide concentrations were recorded breath by breath, together with cardiac output. There was a significant delay in rise of end-tidal isoflurane concentration after Fluosol infusion. However, because cardiac output could not be held constant during each experiment, and because cardiac output also affects the rate of rise of alveolar anesthetic concentration, a physiological computer model was used to compare the isoflurane blood/gas partition coefficients that must have existed to account for the observed end-tidal levels before and after Fluosol infusion, while taking cardiac output variation into account. Post-Fluosol blood/gas partition coefficients calculated in this way (2.59 +/- 0.51 SD) were significantly different (P less than 0.001) from pre-Fluosol levels (1.45 +/- 0.15 SD) and were not significantly different from post-Fluosol partition coefficients calculated by volume-weighted averaging (2.91 +/- 0.36 SD). This indicates that the delay observed was attributable in large part to increased solubility of isoflurane in blood after addition of Fluosol. Based on their similar liquid/gas partition coefficients in Fluosol, similar delays should occur with halothane and enflurane.

Anesthesia, Inhalation↗
PubMed1991

A system model for closed-circuit inhalation anesthesia. I. Computer study.

Developing a custom computer program to simulate the uptake, distribution, and elimination of inhalational anesthetics allows the anesthesiologist to address specific problems, but extensive skills are required to translate the involved processes first into a set of mathematical equations and then into a satisfactory computer program. The first step is often facilitated by solutions offered in the literature. The second step demands computer proficiency that is often not available, but this problem can be obviated by means of a special-purpose simulation language (SPSL). We therefore constructed a model for closed-circuit inhalation anesthesia with the aid of the block-structured SPSL TUTSIM. Noticeable differences with previous models are that the linear, 14-compartment basic model does not assume a constant alveolar concentration and mimics circulation times through the use of blood pools. Advanced features of the SPSL were used to develop variants of the basic model to simulate feedback-controlled isoflurane administration, nitrous oxide uptake, and the impact of a nonlinearity by incorporating the effect of enflurane on cardiac output. Two variants were concatenated to form a multiple model showing the concentration and second-gas effects. The model was capable of reproducing the anesthetic uptake from previous experimental studies for nitrous oxide. After its validation for other anesthetic agents, the model can be used for clinical, teaching, and research purposes. The SPSL freed the authors from the problems associated with computer programming and allowed them to concentrate on the structure of the model.

Anesthesia, Closed-Circuit↗
PubMed2004

The bispectral index does not correlate with clinical signs of inhalational anesthesia during sevoflurane induction and arousal in children.

PURPOSE: Validation of the bispectral index (BIS) in children requires correlating BIS with several levels of sedation, hypnosis and anesthesia. Our purpose was to compare BIS values with objective assessments of the level of hypnosis in children. We postulated that BIS predicted the level of anesthesia during induction and emergence in children. METHODS: In a prospective observational study, we evaluated the BIS monitor in 87 children (ages: 0.3 to 14 yr) ASA physical status I-II undergoing general surgery under sevoflurane and nitrous oxide. Clinical signs of inhalational anesthesia (CSA), the motor response to surgical incision and signs of arousal were used as indicators of the depth of anesthesia. CSA and BIS measurements were paired every minute during induction and emergence until arousal. RESULTS: CSA scores decreased during induction and increased during emergence (P < 0.001) and correlated with changes in sevoflurane concentrations (r = -0.46; P < 0.001). BIS was associated with changes in CSA scores during induction (r = 0.49; P < 0.01) and emergence (r = 0.62; P < 0.01), but the ranges of individual BIS values overlapped several levels of hypnosis. A BIS value greater than 50 had a positive predictive value of 25% for distinguishing between responders and non-responders to surgical incision. A BIS score equal or greater than 72 had a predictive value of 63% for discriminating between pre-arousal and arousal. CONCLUSIONS: BIS correlates with several levels of hypnosis during inhalational induction and emergence in children, but individual BIS values show large inter-individual variability. The BIS monitor identified the physiological changes associated with arousal and distinguished the effects of preoperative sedation during emergence. The use of movement as an endpoint of hypnosis during surgical stimulation does not correlate with BIS values in children. The large inter-individual variability of BIS at different levels of anesthetic depth may limit the applicability of BIS to pediatric anesthesia.

Adolescent↗
PubMed1989

[Alfentanil combination anesthesia in adeno-tonsillectomy in children--a comparison with ethrane inhalation anesthesia].

In two groups, each comprising 25 children undergoing adenotonsillectomy, two different methods of anaesthesia were used. Group I received ethrane inhalations, group II an alfentanil combination anaesthesia. The objective was to find out, whether or not the two methods differed in respect of haemodynamics, side-effects and practicability. In the patients of group II more haemodynamic stability, less ethrane consumption and faster postanaesthetic recovery was observed. The incidence of vomiting was equally low in both groups. Other side-effects ascribable to alfentanil, such as respiratory depression, chest rigidity and bradycardia, had no clinical significance. One may conclude from the results, that on account of the advantages described an alfentanil combination anaesthesia represents a true alternative to the routinely used "pure" inhalation anaesthesia in children undergoing adenotonsillectomy.

Adenoidectomy↗
PubMed1998

[Augmentation of the neuromuscular blocking effect of mivacurium during inhalation anesthesia with desflurane, sevoflorane and isoflurane in comparison with total intravenous anesthesia].

To evaluate the enhancement of mivacurium-induced neuromuscular block by potent inhalational anaesthetic agents, dose-effect curves for mivacurium were determined in 84 patients scheduled for minor elective surgery during anaesthesia with 1.5 MAC (70% N2O) desflurane, sevoflurane and isoflurane and compared with those under total intravenous anaesthesia (TIVA). Acceleromyography (TOF-Guard) and train of four (TOF) stimulation of the ulnar nerve were used (2 Hz every 12 s). Mivacurium was administered in increments of 25 micrograms kg-1 until a depression of T1 > 95% was reached. ANOVA was used for statistical analysis (alpha = 0.05, beta = 0.2). The depression of T1 during potent inhalational anaesthesia was enhanced compared with TIVA. The ED50 and ED95 of mivacurium were 27 +/- 11 (SD) and 58 +/- 26 micrograms kg-1 for desflurane; 28 +/- 10 and 64 +/- 23 micrograms kg-1 for sevoflurane; and 27 +/- 13 and 55 +/- 27 micrograms kg-1 for isoflurane and were significantly lower than the 35 +/- 7 and 71 +/- 20 micrograms kg-1 for TIVA. The duration 25% revealed a significant difference between the volatile anaesthetic groups (10 +/- 2, 11 +/- 3, 11 +/- 3 min respectively) and the TIVA control group (8 +/- 3 min). The recovery index 25/75 and TOFO.80 were significantly prolonged by desflurane, sevoflurane and isoflurane compared with TIVA (RI25/75 9 +/- 4, 9 +/- 4, 10 +/- 5 respectively vs. 5 +/- 2 min; TOFO.80 27 +/- 10, 28 +/- 9, 29 +/- 9 respectively vs. 18 +/- 4 min). We conclude that the neuromuscular blocking effect of mivacurium is enhanced during anaesthesia with desflurane, isoflurane and sevoflurane compared with TIVA. The duration of action and the recovery time are prolonged. The dose of mivacurium used should be reduced if anaesthesia is maintained with volatile anaesthetics.

Adolescent↗
PubMed2001

[Controversies surrounding pain and inhalation anesthesia in nineteenth century Spain].

The introduction of inhaled anesthetics to Spain in 1847 brought appearances by enthusiastic promotors, prudent and reserved admirers and stubborn adversaries - sparking controversy over the use of the new gases. In some cases debate involved the discussion of various concepts of pain, as is shown by heated exchanges among Eusebio Castelo Serra, Manuel Santos Guerra and Zacarías Benito González in the pages of the journal Boletín de Medicina, Cirugía y Farmacia, in three articles appearing between 1850 and 1851 on the concept of pain: Sobre el dolor de las enfermedades y principalmente en las operaciones quirúrgicas, Modificación de dos instrumentos and Estudios sobre el dolor. Investigation into the authors' biographies and an analysis of the content of the articles has permitted us to reconstruct some aspects of the concept of pain in Spain in the middle of the nineteenth century.

Anesthesia, Inhalation↗
PubMedDate not supplied

[Artificial perfusion-free hypothermia in non-inhalation anesthesia].

Gas exchange and hemodynamic parameters have been determined in the intraoperative and earliest postoperative periods in 146 patients with congenital heart valve defects operated on in conditions of perfusion-free hypothermia and non-inhalation anesthesia with long-term exclusion of the heart from circulation. It has been found that the use of profound central analgesia with fentanyl for hypothermia maintenance is accompanied by favourable and adequate hemodynamic and gas exchange changes in accordance with metabolic demands of the body during cooling and warming. This allows the use of central analgesia for the maintenance of prolonged heart exclusion from circulation with minimal complications in perfusion-free hypothermic protection.

Anesthesia↗
PubMed2005

Effects of inhalant anesthesia: tympanometry validation (R98/217).

OBJECTIVES: The purpose of this study was to determine the best time to assess middle ear status with tympanometry for tympanometric instrument validation. The research question addressed three logical times for tympanometric reading prior to myringotomy. METHODS: Fifty-one children, ranging in age from nine months to 10 years, were recruited for this investigation. Participants underwent inhalant anesthesia for myringotomy and grommet placement with or without adenoidectomy and/or tonsillectomy. Tympanometry data was analyzed across three time periods. RESULTS: Findings indicated that tympanometric readings prior to anesthesia produced the most accurate results. CONCLUSIONS: Implicated in findings, in order to ensure that tympanometric instruments are reliable, typanometric measurements should be taken prior to the administration of any anesthesia.

Acoustic Impedance Tests↗
PubMed1994

[Endocrine stress reaction, hemodynamics and recovery in total intravenous and inhalation anesthesia. Propofol versus isoflurane].

This prospective, randomised study compared total intravenous anaesthesia (TIVA) and inhalation anaesthesia with respect to endocrine stress response, haemodynamic reactions, and recovery. METHODS. The investigation included two groups of 20 ASA I-II patients 18-60 years of age scheduled for orthopaedic surgery. For premedication of both groups, 0.1 mg/kg midazolam was injected IM. Patients in the propofol group received TIVA (CPPV, PEEP 5 mbar, air with oxygen FiO2 33%) with propofol (2 mg/kg for induction followed by an infusion of 12-6 mg/kg.h) and fentanyl (0.1 mg before intubation, total dose 0.005 mg/kg before surgery, repetition doses 0.1 mg). For induction of patients in the isoflurane-group, 5 mg/kg thiopentone and 0.1 mg fentanyl was administered. Inhalation anaesthesia was maintained with 1.2-2.4 vol.% isoflurane in nitrous oxide and oxygen at a ratio of 2:1 (CPPV, PEEP 5 mbar). For intubation of both groups, 2 mg vecuronium and 1.5 mg/kg suxamethonium were injected, followed by a total dose of 0.1 mg/kg vecuronium. Blood samples were taken through a central venous line at eight time points from before induction until 60 min after extubation for analysis of adrenaline, noradrenaline (by HPLC/ECD), antidiuretic hormone (ADH), adrenocorticotropic hormone (ACTH), and cortisol (by RIA). In addition, systolic arterial pressure (SAP) heart rate (HR), arterial oxygen saturation (SpO2), and recovery from anaesthesia were observed. RESULTS. Group mean values are reported; biometric data from both collectives were comparable (Table 1). Plasma levels of adrenaline (52 vs. 79 pg/ml), noradrenaline 146 vs. 217 pg/ml), and cortisol (82 vs. 165 ng/ml) were significantly lower in the propofol group (Table 2, Figs. 1 and 3). Plasma levels of ADH (4.8 vs. 6.1 pg/ml) and ACTH (20 vs. 28 pg/ml) did not differ between the groups (Table 2, Figs 2 and 3). SAP (128 vs. 131 mmHg) was comparable in both groups, HR (68/min vs. 83/min) was significantly lower in the propofol group, and SpO2 (97.1 vs 97.4%) showed no significant difference (Table 3). Recovery from anaesthesia was slightly faster in the propofol group (following of simple orders 1.9 vs. 2.4 min, orientation with respect to person 2.4 vs. 3.4 min, orientation with respect to time and space 2.8 vs. 3.7 min), but differences failed to reach statistical significance. CONCLUSIONS. When compared with isoflurane inhalation anaesthesia, moderation of the endocrine stress response was significantly improved during and after TIVA with propofol and fentanyl. Slightly shorter recovery times did not lead to an increased stress response. With respect to intra- and postoperative stress reduction, significant attenuation of sympatho-adrenergic reaction comparable SAP and reduced HR, sympatholytic and hypodynamic anaesthesia with propofol and fentanyl seems to be advantageous for patients with cardiovascular and metabolic disorders. For this aim, careful induction and application of individual doses is essential.

Adolescent↗
PubMed1984

Inhalational anesthesia and histamine release during bronchospasm.

The influence of inhalational anesthetics on histamine released during bronchospasm induced by Ascaris antigen aerosol was studied in Basenji-Greyhound (BG) dogs. Five BG dogs were anesthetized with thiopental and halothane on separate occasions and challenged with Ascaris antigen aerosol for five minutes. Pulmonary resistance (RL), dynamic compliance (Cdyn), and arterial plasma histamine levels were measured over 30 min following antigen exposure. Prior to antigen challenge, RL, Cdyn, and histamine levels were similar in thiopental- and halothane-anesthetized dogs. The peak change in RL and Cdyn occurred 10 min after the start of antigen challenge. RL increased 3.0 +/- 0.4-fold (mean +/- SEM) in thiopental-anesthetized dogs as compared with 1.6 +/- 0.2-fold in halothane-anesthetized dogs (P less than 0.05). Cdyn decreased to a similar extent in both groups, with maximal decreases of 0.53 +/- 0.08 and 0.53 +/- 0.09 times the prechallenge value for thiopental- and halothane-anesthetized dogs, respectively. Plasma histamine levels peaked at 5 min. Plasma histamine increased to 8.0 +/- 5.0 ng/ml in thiopental-anesthetized dogs compared with 10.7 +/- 4.7 ng/ml in halothane-anesthetized dogs. Histamine levels were not significantly different during or after antigen challenge between thiopental- and halothane-anesthetized dogs. Halothane, but not thiopental, significantly attenuated the increase in RL provoked by antigen challenge. However, arterial plasma histamine levels were similar during both anesthetics. Therefore, the authors conclude that the protective effect of halothane on airways was not due to an inhibition of release of histamine from mast cells.

Anesthesia, Inhalation↗
PubMed1990

[Correction on congenital heart defects under conditions of hypothermia without perfusion and non-inhalation anesthesia].

The clinical and pathophysiological indices were determined in the operative and immediate postoperative periods in 221 patients with various congenital heart diseases, with consideration for the degree of preoperative disorders of hemodynamics. The operations were conducted under conditions of non-inhalation anesthesia and various-level hypothermal protection without perfusion, with exclusion of the heart from circulation for up to 52 minutes. The main complications developing in the operative and postoperative periods were determined. It is proved that the processes of metabolism and blood oxygen-transport function are interlinked in operations conducted under these conditions. It is also proved that the operations are safe and effective.

Adolescent↗
PubMed1985

Intestinal circulation during inhalation anesthesia.

This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86Rb and 9-microns spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-microns spheres through the intestines reflects the arteriovenous shunting of blood. Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO2) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1999

Equipment for inhalant anesthesia.

When used properly, anesthesia machines, breathing systems, anesthesia ventilators, and ancillary equipment allow the safe and efficient use of the inhalant anesthetics. Several veterinary anesthesia machines and ventilators have been introduced over the last few years. This article includes a discussion of some of these new pieces of anesthesia equipment, with particular emphasis on changes and innovations in the design of the equipment. In addition, principles of use and care of various anesthetic equipment is included where appropriate.

Anesthesia, Inhalation↗
PubMed2002

Recent advances in inhalation anesthesia.

Both desflurane and sevoflurane offer theoretical and practical advantages over other inhalation anesthetics for horses. The lower solubility of both agents provides improved control of delivery and helps to counteract the confounding influence of the voluminous patient breathing circuit commonly used for anesthetizing horses. The lower solubility should account for faster rates of recovery compared with the older agents; whether or not the quality of recovery differs remains to be objectively evaluated in a broad range of circumstances. The pharmacodynamic effects are, in large part, similar to those of isoflurane (e.g., low arrhythmogenicity) but with some differences. For example, desflurane may be overall more sparing to cardiovascular function (especially during controlled ventilation) compared with isoflurane and sevoflurane, which are roughly similar. Respiratory depression with both new agents is equal to or more depressing than isoflurane, suggesting the use of mechanical ventilation, especially in circumstances of prolonged management (i.e., hours of anesthesia). Both new anesthetics, not surprisingly, are expensive. From this point there are some agent-unique considerations. The anesthetic potency of both agents is less than that of isoflurane, which influences the cost of anesthesia, but also places an upper limit on inspired oxygen concentration (of particular concern with desflurane). Both agents require new vaporizers, but because of the high boiling point and steep vapor-pressure curve of desflurane, new technology was required. This translates into more costly equipment, adding to the cost of desflurane use. In addition, electricity is necessary for the new desflurane vaporizer to function, which limits its portability and adds additional practical considerations in its clinical use. On the other hand, desflurane strongly resists degradation both in vitro and in vivo, but in vitro degradation of sevoflurane by CO2 absorbents may produce renal injury. This may be true especially in association with low fresh-gas inflow rates (used to reduce the cost of using the new agent), and university based practices, where prolonged anesthesia is common.

Anesthesia, Inhalation↗
PubMed1987

[The behavior of free thyroxine and triiodothyronine concentrations after short-term balanced inhalation anesthesia].

Acute changes involving the hormones thyroxine (T4) and triiodothyronine (T3) followed by hyper -or hypothyroid crises will lead to both cardiovascular and metabolic disorders. Due to highly sensitive mechanisms controlling central hormonal production and peripheral enzymatic conversion (c.g. T4 to T3), numerous pharmacologically effective substances will influence the kinetics of these hormones. Thus, agents routinely used in anesthetic practice and their metabolites may disturb hormonal regulation in particular due to their central effectiveness [1, 2,5-7]. Based on this premise, it was our goal to search for anesthetic-induced hormonal changes in euthyroid patients living in a goiter-endemic area scheduled for short, elective orthopedic operations. Investigations were done in 21 outpatients (mean age: 24 years, mean body wt.: 64 kg) undergoing minor surgical procedures of the extremities. No clinical signs of thyroid disturbances could be observed preoperatively in the patients. Immediately after intravenous premedication (meperidine HCl 0.75 mg/kg and atropine 0.25 mg), anesthesia was induced (thiopentone 5 mg/kg) and continued by inhalation via face; mask using volatile agents: halothane, isoflurane, or enflurane (O2: N2O; FiO2 = 0.33). According to the anesthetic agent administered (halothane, isoflurane, enflurane), patients were divided into three groups of 7 patients each as listed in Table 1. Blood samples to determine free serum T4 (fT4) and T3 (fT3) as an expression of biologically available T4/T3, unconjugated to transport globulins, were drawn twice: immediately before premedication; and postoperatively after the patient had regained consciousness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[Sevoflurane inhalation anesthesia for short surgical interventions].

Sevoflurane, a new halogen inhalation anesthetic for mononarcosis, was used in 33 patients aged 22-57 years subjected to noncavitary general surgical and urological operations lasting for 50 +/- 9 min. Induction anesthesia consisted in sevoflurane inhalation in a semi-open contour. The anesthetic was delivered first in a dose of 0.2 vol% which was increased to 3-4 vol% by the end of induction (1.5-1.8 MAC). Laryngeal mask was used in 28 patients, in the rest tracheal intubation was carried out after succinyl choline. Maintenance dose of sevoflurane was 2-3 vol%. Electrocardiogram was recorded and arterial pressure monitored by indirect methods, pulse oxymetry and capnography were carried out. For evaluating the probable toxic effect, serum levels of total bilirubin, SGPT, creatinine, alkaline phosphatase, urea, albumin, potassium, and sodium were measured. Sevoflurane did not suppress the respiration and allowed assisted ventilation of the lungs, if necessary. No appreciable changes in the hemodynamics were observed, though heart rate was to be monitored. There were no biochemical shifts indicative of hepatic or renal involvement. Sevoflurane is recommended for total anesthesia in short non-cavitary interventions as mononarcosis, that is, such anesthesia requires virtually no extra narcotics, neuroleptics, or ataractics.

Adult↗