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PubMedDate not supplied

[Inhalational anesthesia during adenoidectomy in children].

The paper deals with the comparison of inhalational anesthesia using a fluoroethane-monooxide-oxygen mixture in apparatus-mask and endotracheal fashions in children during adenotomy. Children aged 4 to 15 years, who had undergone apparatus-mask (n = 51) and endotracheal (n = 57) anesthesia, were examined. The patients were divided into two age groups: 4-8 years and 8-15 years. The parameters of central hemodynamics, the data of cardiointervalograms, respiration rate, and SatO2 were studied. The studies were repeated 5 times for each patient at the stages of anesthesia and surgery. The use of inhalational fluroethane-monoxide-oxygen anesthesia in apparatus-mask and endotracheal fashions was found to be inadequate in children during adenotomy without addition of analgesics. In 4-8-year-old children, apparatus-mask fluoroethane-monooxide-oxygen anesthesia during surgery is ineffective, as shown by the data of central hemodynamics and cardiointervalography. The pain syndrome was observed in the postoperative period. Endotracheal fluoroethane-monooxide-oxygen anesthesia fails to ensure adequate analgesia during intubation and surgery. The pain syndrome and sympathicotony were seen in the postoperative period. In 8-15-year-old children, apparatus-mask fluoroethane-monooxide-oxygen anesthesia is characterized by prehypoxia and inadequate anesthesiological defense at the traumatic stage of an operation. In endotracheal fluoroethane-monooxide-oxygen anesthesia, the stability of cardiac output is maintained by the tension of more mature compensatory mechanisms responsible for regulation of central hemodynamics. A marked sympathicotony is noted at the traumatic stage of a surgery, as evidenced by cardiointervalography. There is motor agitation in the postoperative period.

Adenoidectomy↗
PubMed1993

The predictive performance of a system model for enflurane closed-circuit inhalational anesthesia.

BACKGROUND: Previously, the authors described a system model for closed-circuit inhalational anesthesia, and demonstrated close agreement between end-tidal isoflurane concentrations measured in their clinical study and those predicted by the model. The predictive performance of their model has not, however, been tested for anesthetics featuring nonpulmonary elimination (NPE). METHODS: The authors quantified the predictive performance of two versions (A and C) of the model in 50 patients by comparing the predicted and the measured alveolar concentration-time profiles after bolus injections of liquid enflurane into the expiratory limb of the closed system. Version A did not incorporate NPE, but version C emulated NPE by adopting the irreversible loss of a fraction of the enflurane present in the arterial hepatic blood flow (0.131, derived from a mass balance study performed by others). For each concentration measured by mass spectrometry, the authors used computer simulations of version A and C to calculate a predicted concentration for both versions. For each patient, the authors calculated the bias (indicating systematic over- or underprediction) and the scatter of the prediction errors (indicating typical error size). RESULTS: The authors administered a total of 379 ml of liquid enflurane via 466 injections. A total of 18,432 alveolar concentrations (one per 10-s period; average concentration = 0.96 vol%) were measured. The bias and the scatter, both given as mean (and SD), were 10.0 (13.1)% and 11.8 (3.9)% for version A and -0.8 (11.4)% and 11.4 (2.8)% for C. The bias for version C was closer to zero; the scatters were similar. CONCLUSIONS: Version C incorporating NPE performs better than version A. The accuracy that was obtained should encourage the use of version C for clinical, teaching, research, economic, and ecologic purposes.

Adult↗
PubMedDate not supplied

[Batching of low-concentration anesthetics with evaporators used in apparatuses for inhalation anesthesia].

The accuracy of the anesthetic vaporizers with modern vaporizing devices is complicated by necessity of providing small anesthetic vapor concentration for a wide range of gas flows, especially at small flows, and at use of a combination of inhalation anesthesia with intravenous one. Compliance with the requirements of the international standards concerning the accuracy of low-concentration anesthetic vapor batching also does not provide management of anesthesia depth at various stages of surgical operations. The problem is solved well by replacement traditional vaporizers with so-called barbotage ones equipped by adjustment of vapor concentration by modem electronic methods. It is even more promising to use direct injection of the liquid anesthetics into the respiratory contour of infusion pump. However, because individual sensitivity of patients to anesthetics is rather variable, these devices do not provide regulation of the depth of anesthesia. Therefore, stability rather than accuracy of batching of low-concentration anesthetics with evaporators used in apparatuses for inhalation anesthesia is of cardinal importance, Methods of objective instrumental evaluation of the depth of anesthesia require further research and implementation.

Anesthesia, Inhalation↗
PubMed2005

Influence of inhalation anesthesia assessed by comprehensive gene expression profiling.

Although general anesthesia is routinely used as an essential surgical procedure and its harmlessness has been evaluated and endorsed by clinical outcomes, little is known about its comprehensive influence that is not reflected in mortality and morbidity. In this paper, we have shown that inhalation anesthesia affected the expression of <1.5% of >10,000 genes, by analyzing the expression profiles for multiple organs of rats anesthetized with sevoflurane. The small number of transcripts affected by the inhalation anesthesia comprised those specific to single and common in multiple organs. The former included genes mainly associated with drug metabolism in the liver and influenced by agents such as amphetamine in the brain. The latter contained multiple circadian genes. In the brain, we failed to detect the alteration of the clock gene expression with the exception of Per2, assuming that anesthesia perturbs circadian rhythms. Our findings provide the first assessment for the influence of inhalation anesthesia by approaches of experimental biology and genome science.

Anesthetics, Inhalation↗
PubMed2005

A comparison of target-controlled infusion versus volatile inhalant anesthesia for heart rate, respiratory rate, and recovery time in a rat model.

We conducted this study to determine whether heart rate, respiratory rate, and recovery time differed significantly between rats receiving target-controlled infusion (TCI) and those under volatile inhalant anesthesia. TCI rats received intravenous propofol at an average effect site concentration of 11.3 microg/ml or propofol plus ketamine (5 mg/ml of propofol) at an average effect site concentration of 8.7 microg/ml. Inhalant anesthesia rats received isoflurane (average, 1.8%) delivered in medical-grade air. We used a tail-clamp response test to determine when a surgical plane of anesthesia was attained. Anesthesia was continued for 1 h from the first negative tail-clamp test. During this time the test was repeated every 10 min to confirm that a surgical plane of anesthesia was being maintained. Anesthesia then was discontinued, and the animals were monitored continuously until they recovered. Average heart rate was higher for rats during anesthesia with isoflurane compared with TCI propofol-ketamine (P =0.0053). Average respiratory rate was higher for TCI regimens compared with isoflurane anesthesia, with male rats having consistently faster respiratory rates than females (P <0.001). Recovery time was longer for both TCI regimens compared with isoflurane (P <0.001). Once venous access was accomplished, TCI anesthesia with propofol or propofol combined with a low dose of ketamine was comparable to an isoflurane inhalant regimen in ease of administration and control of the anesthetic event when used in rats for procedures of 1-h duration. Respiratory rate was increased and recovery time was longer for rats receiving the TCI regimens.

Anesthesia Recovery Period↗
PubMed1985

Inhalation anesthesia in adult cattle.

An inhalation technique was used for anesthesia during ileal cannulation in five adult cows. Following sedation with intravenous acepromazine, anesthesia was induced intravenously with thiopental sodium in 5% glyceryl guaiacolate solution. Endotracheal intubation was performed and anesthesia maintained with halothane in oxygen via a circle system with a precision vaporizer. In all cases, induction was smooth and no difficulties were experienced during the maintenance of anesthesia. Total anesthesia time was 1.5 to 2.5 hours. Following completion of the surgical procedure, which was performed with the animal in left lateral recumbency, each cow was rolled to a sternal position and supported, if necessary. The endotracheal tube was left in place, with oxygen administration continued, until the animal was able to swallow. Recoveries were rapid and all animals were ambulatory within 30 minutes after completion of the surgery. The only post-operative complication due to anesthesia was transient mouth soreness in two cases, attributed to the use of a mouth speculum during intubation.

Anesthesia, Inhalation↗
PubMed1992

Ethanol monitoring of transurethral prostatic resection during inhaled anesthesia.

The purpose of this study was to examine the precision of a method of breath-alcohol analysis used to monitor absorption of irrigating fluid during transurethral resection of the prostate performed under inhaled anesthesia. A breath-alcohol analyzer (Alcolmeter SD-2) was placed between the endotracheal tube and the Bains' circuit. The concentration of ethanol in the breath, serum sodium concentration, and volumetric fluid balance were measured at 10-min intervals during 38 operations when the irrigating fluid contained 1.5% glycine and 1% ethanol. Ethanol monitoring detected absorption rates that exceeded 14 +/- 8 mL/min (mean +/- SD). In 17 patients in whom hyponatremia developed immediately in connection with absorption, the volume of irrigating fluid absorbed (up to 1950 mL) could be predicted from a single expired-breath test with a standard error of 325 mL. When the alcohol measurements were corrected for absorption time, the standard error was 215 mL. Seven other patients received 2.2% wt/vol glycine as irrigating fluid, and ethanol (0.35 g/kg) was administered by intravenous infusion. The direct and indirect measurements of the blood-alcohol concentration agreed well. These results confirm that ethanol monitoring is a viable technique during inhaled anesthesia for transurethral resection of the prostate.

Absorption↗
PubMed1982

Inhalation anesthesia in experimental radiotherapy: a reliable and time-saving system for multifractionation studies in a clinical department.

An inhalation anesthesia system has been employed to overcome several of the limitations associated with the use of sodium pentobarbital and other i.p. administered anesthetics in experimental radiotherapy. The described method is reliable and time-saving. The depth and duration of anesthesia are easily controllable. Only 4 deaths have occurred with more than 6000 animal exposures. The use of polystyrene jigs is shown to provide adequate thermal isolation. Oxygen as a carrier of the anesthetic agent is expected to prevent a reduced tissue oxygenation and its radiobiological consequences. The whole system is constructed as a mobile unit in which up to 16 mice or rats can be anesthetized simultaneously and irradiated in a single field with clinical treatment equipment during short time intervals between patient irradiations. The described advantages of this method make it specially suited for experiments with protracted fractionation schedules.

Anesthesia, Inhalation↗
PubMed1995

Change in cerebral blood flow velocity with onset of EEG silence during inhalation anesthesia in humans: evidence of flow-metabolism coupling?

In eight subjects anesthetized with moderate to high doses of inhalation anesthetics (isoflurane or desflurane) during normocapnia, the onset of electrical silence in EEG was associated with a sudden reduction of blood flow velocity monitored from the middle cerebral artery. The magnitude of this reduction was 38 +/- 11% (mean +/- SD; range 24-44%). The change in EEG always preceded the change in flow velocity by 5-7 s. These observations suggest that some flow-metabolism coupling mechanism is preserved during inhalation anesthesia in humans.

Adolescent↗
PubMed1993

Recovery of horses from inhalation anesthesia.

To study behavioral and cardiopulmonary characteristics of horses recovering from inhalation anesthesia, 6 nonmedicated horses were anesthetized under laboratory conditions on 3 different days, with either halothane or isoflurane in O2. Anesthesia was maintained at constant dose (1.5 times the minimum alveolar concentration [MAC]) of halothane in O2 for 1 hour (H1), halothane in O2 for 3 hours (H3), or isoflurane in O2 for 3 hours (I3). The order of exposure was set up as a pair of Latin squares to account for horse and trial effects. Circulatory (arterial blood pressure and heart rate) and respiratory (frequency, PaCO2, PaO2, pHa) variables were monitored during anesthesia and for as long as possible during the recovery period. End-tidal percentage of the inhaled agent was measured every 15 seconds by automated mass spectrometry, then by hand-sampling after horses started moving. Times of recovery events, including movement of the eyelids, ears, head, and limbs, head lift, chewing, swallowing, first sternal posture and stand attempts, and the number of sternal posture and stand attempts, were recorded. The washout curve or the ET ratio (end-tidal percentage of the inhaled agent at time t to end-tidal percentage of the inhaled agent at the time the anesthesia circuit was disconnected from the tracheal tube) plotted against time was similar for H1 and H3. The slower, then faster (compared with halothane groups) washout curve of isoflurane was explainable by changes in respiratory frequency as horses awakened and by lower blood/gas solubility of isoflurane. The respiratory depressant effects of isoflurane were marked and were more progressive than those for halothane at the same 1.5 MAC dose. During the first 15 minutes of recovery, respiratory frequency for group-I3 horses increased significantly (P < 0.05), compared with that for the halothane groups. For all groups, arterial blood pressure increased throughout the early recovery period and heart rate remained constant. Preanesthesia temperament of horses and the inhalation agent used did not influence the time of the early recovery events (movement of eyelids, ears, head, and limbs), except for head lift. For events that occurred at anesthetic end-tidal percentage < 0.20, or when horses were awake, temperament was the only factor that significantly influenced the nature of the recovery (chewing P = 0.04, extubation P = 0.001, first stand attempt P = 0.008, and standing P = 0.005).(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia Recovery Period↗
PubMed1996

Pressure support improves efficiency of spontaneous breathing during inhalation anesthesia.

STUDY OBJECTIVE: To determine if reducing respiratory muscle load or increasing tidal volume (VT) with pressure support (PS) would improve ventilatory efficiency by reducing respiratory rate (RR) and resting PaCO2. DESIGN: Prospective, and patient-controlled, with randomized treatment crossover. SETTING: University cancer center and research institute. PATIENTS: ASA status I and II patients scheduled to undergo inhalation anesthesia for operations in which neuromuscular relaxation is undesirable. INTERVENTIONS: Propofol and succinylcholine were used to induce anesthesia and facilitate tracheal intubation. General anesthesia was maintained with desflurane, nitrous oxide, and oxygen. Patients breathed spontaneously at atmospheric pressure for 15 minutes and then randomly received alternate 15-minute trials of PS adjusted to provide either 5 cmH2O or a level titrated to produce VT of 8 ml/kg body weight. Then patients breathed spontaneously at atmospheric pressure for 15 minutes. MEASUREMENTS AND MAIN RESULTS: In 20 patients aged 52 +/- 11 years and weighing 72 +/- 18 kg, airway gas flow and pressure, esophageal pressure, arterial blood gas tensions and pH, and mean arterial pressure (MAP) were measured. Heart rate (HR), VT, RR, minute ventilation (VE), carbon dioxide production (VCO2), ratio of dead space to VT (VD/VT), and inspiratory work of breathing (WI) were calculated. End-tidal desflurane (6.7 +/- 0.4%), VCO2 (142 +/- 39 ml/min), HR, and MAP were unchanged throughout the study. WI, RR, VE, VD/VT, and PaCO2 were reduced significantly when PS was titrated to produce a VT of 8 ml/kg and spontaneous breathing before and after PS trials (p < 0.05). CONCLUSIONS: PS titrated to produce a near normal VT improves the efficiency of spontaneous breathing by lowering RR and PaCO2 while preserving hemodynamic homeostasis in patients undergoing inhalation anesthesia. Lesser PS levels will unload the respiratory muscles, but have no effect on RR or PaCO2.

Anesthesia, Inhalation↗
PubMed2005

Canadian pediatric anesthesiologists prefer inhalational anesthesia to manage difficult airways.

PURPOSE: To survey Canadian pediatric anesthesiologists to assess practice patterns in managing pediatric patients with difficult airways. METHODS: Canadian pediatric anesthesiologists were invited to complete a web survey. Respondents selected their preferred anesthetic and airway management techniques in six clinical scenarios. The clinical scenarios involved airway management for cases where the difficulty was in visualizing the airway, sharing the airway and accessing a compromised airway. RESULTS: General inhalational anesthesia with spontaneous respiration was the preferred technique for managing difficult intubation especially in infants (90%) and younger children (97%), however, iv anesthesia was chosen for the management of the shared airway in the older child (51%) where there was little concern regarding difficulty of intubation. Most respondents would initially attempt direct laryngoscopy for the two scenarios of anticipated difficult airway (73% and 98%). The laryngeal mask airway is commonly used to guide fibreoptic endoscopy. The potential for complete airway obstruction would encourage respondents to employ a rigid bronchoscope as an alternate technique (17% and 44%). CONCLUSION: Inhalational anesthesia remains the preferred technique for management of the difficult pediatric airway amongst Canadian pediatric anesthesiologists. Intravenous techniques are relatively more commonly chosen in cases where there is a shared airway but little concern regarding difficulty of intubation. In cases of anticipated difficult intubation, direct laryngoscopy remains the technique of choice and fibreoptic laryngoscopy makes a good alternate technique. The use of the laryngeal mask airway was preferred to facilitate fibreoptic intubation.

Anesthesia, Inhalation↗
PubMed2002

Calibrated pneumoperitoneal venting to prevent N2O accumulation in the CO2 pneumoperitoneum during laparoscopy with inhaled anesthesia: an experimental study in pigs.

UNLABELLED: Nitrous oxide (N2O) accumulates in the CO2 pneumoperitoneum during laparoscopy when N2O is used as an adjuvant for inhaled anesthesia. This may worsen the consequences of gas embolism and introduce a fire risk. In this study, we quantified the pneumoperitoneal gas venting necessary to prevent significant contamination by inhaled N2O. Four domestic pigs (26-30 kg) were anesthetized and ventilated with 66% N2O in oxygen. A CO2 pneumoperitoneum was insufflated and maintained at a pressure of 12 mm Hg. Each animal underwent three experimental conditions, in random sequence, for 70 min each: 1) no pneumoperitoneal leak, 2) leak of 2 L every 10 min (12 L/h), and 3) leak of 4 L every 10 min (24 L/h). Every 10 min, pneumoperitoneal gas samples were analyzed for fractions (FPn) of N2O and CO2. Without leaks, FPnN2O increased continually and reached 29.58% +/- 3.15% at 70 min. With leaks of 2 and 4 L every 10 min (12 and 24 L/h), FPnN2O reached a plateau of <10% after 30 min. We conclude that calibrated pneumoperitoneal venting of 12 or 24 L/h is enough to prevent the constitution of potentially dangerous pneumoperitoneal gas mixtures if venting is constant. IMPLICATIONS: External venting calibrated at four or eight initial pneumoperitoneal volumes per hour with compensation by fresh CO2 is sufficient to prevent nitrous oxide buildup of more than 10% in the pneumoperitoneum during laparoscopy with inhaled general anesthesia if venting is constant.

Anesthesia, Inhalation↗
PubMed1994

[Short anesthesia in rats: an injection or an inhalation anesthesia].

First we describe the application of an injection anaesthesia in a specific strain of rats and test its usefulness under practical conditions. Application (i.p.) of the described dose according to the animals body-weight resulted in an acceptable anaesthesia, which lasted approximately 50 minutes in male rats and 80 minutes in female rats. Next we compare the common ether anaesthesia with an other inhalation anaesthesia (Methoxyflurane) which, by using a self-made mask, could be prolonged without any problem for at least 15 minutes ("prolonging-time"). A correlation was found between the duration of the prolonging-time and the awakening time. Inhalation anaesthesia using Methoxyflurane obviously affected the animals health and well-being less than the conventional ether anaesthesia.

Anesthesia, General↗