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PubMed2006

An interchangeable Mapleson A-E breathing system is practical and cost effective.

BACKGROUND: In locations where oxygen and anesthesia gas supplies are limited, and where circle systems are not practical, means to reduce fresh gas flow during maintenance of inhalational anesthesia are of potential value. We investigated whether a common transport breathing apparatus could be modified to allow interchange between Mapleson D (Map-D) and Mapleson A (Map A) configurations. METHODS: A common Map-D transport system was converted to a Map-A system by switching positions of the exhaust valve and the elbow connector where fresh gas is delivered; these two breathing systems were compared in this study. The key question was whether rebreathing of CO2 could be eliminated at a lower fresh gas flow rate (FGF) with the Map-A design. A structured protocol was followed. RESULTS: A mean decrease in FGF of 2.8 l/min was seen with the Map-A apparatus when compared with the Map-D (P=0.003). With no significant differences in physiologic or anesthetic variables, FGF/V(E) was significantly lower with the Mapleson A configuration than with the Mapleson D system design (1.1 vs. 1.8; P=0.007). The extent to which FGF could be lowered when switching between Mapleson D and A systems correlated strongly with the patients' respiratory rate while under anesthesia (r=0.45, P<0.01). CONCLUSIONS: Cost and resource savings can be realized through the use of a breathing system modification that achieves appropriate ventilation at lower fresh gas flows.

Adult↗
PubMed1981

[Use of head tent for anesthesia of children (author's transl)].

The authors relate their experience of 61 inhalation anesthesia of children from 5 months to 15 years years old. Head-tent is usually employed for intensive care as a method to administrate pure oxygen. Children are often afraid of the face-mask and tolerate head-tent easier. Three different protocols were studied: Nitrous oxide and oxygen mixture at different level (50 p. cent oxygen, 50 p. cent nitrous-oxide; or 30 p. cent oxygen, 70 p. cent nitrous oxide). The authors also used halothan in the inhalated mixture. The rebreathing level of CO2 in the head-tent according to the gas flow was measured. No incident, nor accident are related. This new anesthetic apparatus is easy to use, well accepted by children.

Adolescent↗
PubMed1995

[Electrophysiology of the central nervous system in effective anesthesia].

In authors' opinion, the more precise methods for controlling the depth and efficiency of general anesthesia are those which are based on the direct control over the intraoperative status of the central nervous system which reflects the time course of the status in question. Whether monitoring of the early components of somatosensory evoked potentials could be used for multimodality anesthesia was analysed. As high as 50% or lower decreases in the amplitude of the complex N19-P23 were typical of adequate defense, irrespective of anesthesias. The authors provide evidence for the efficiency of their procedure for controlling the depth and efficiency of general anesthesia. Some electroencephalographic phenomena of anesthesia were analysed with computed monitoring. The authors showed that there was a relative value of such signs of inadequate anesthesia as interhemispheric asymmetry by the leading spectral frequency and the power index of deep rhythms. Despite the procedure used (neuroleptic analgesia, ataralgesia, inhalation anesthesia, etc.), the effective anesthesia exhibited pronounced power peaks, otherwise there was a chaotic activity of the central nervous system. The physiological and clinical values of the phenomena detected are discussed in the paper.

Anesthesia, General↗
PubMed2000

Combined lidocaine and salbutamol inhalation for airway anesthesia markedly protects against reflex bronchoconstriction.

BACKGROUND: Lidocaine inhalation, in subjects with bronchial hyperreactivity, attenuates evoked bronchoconstriction but also irritates airways. Whether salbutamol pretreatment can mitigate airway irritation and whether combined treatment offers more protection than treatment with either drug alone is unknown. Therefore, we evaluated the effects of the inhalation of lidocaine, salbutamol, lidocaine and salbutamol combined, and placebo on an inhalational histamine challenge. METHODS: Fifteen patients with mild asthma were selected by a screening procedure (ie, a provocative concentration of a substance [histamine aerosol of < 18 mg/mL] causing a 20% fall in FEV(1) [PC(20)]). On 4 different days after pretreatment with the inhalation of lidocaine (5 mg/kg), inhalation of salbutamol (1.5 mg), combined treatment, or placebo, the histamine challenge was repeated. RESULTS: The baseline FEV(1) after lidocaine inhalation but prior to the histamine challenge decreased by > 5% in 7 of 15 volunteers, with a mean (+/- SD) decrease from 3.82 +/- 0.90 to 3.54 +/- 0.86 L (p = 0.0054). The baseline PC(20) for histamine was 6.4 +/- 4.3 mg/mL. Both lidocaine and salbutamol inhalation significantly increased PC(20) more than twofold (14.9 +/- 13.7 and 16.8 +/- 10.9 mg/mL, respectively; p = 0, 0007) at a lidocaine plasma concentration of 0.7 +/- 0.3 microg/mL. Combined treatment quadrupled the PC(20) to 29.7 +/- 20.3 mg/mL (vs lidocaine, p = 0.002; vs salbutamol, p = 0.003). CONCLUSIONS: Thus, histamine-evoked bronchoconstriction, as a model of reflex bronchoconstriction, can be significantly attenuated by salbutamol or lidocaine inhalation. However, lidocaine inhalation causes significant initial bronchoconstriction. The combined inhalation of salbutamol and lidocaine prevents the initial bronchoconstriction observed with lidocaine alone and offers even more protection to a histamine challenge than either lidocaine or salbutamol alone. Therefore, the combined inhalation of lidocaine and salbutamol can be recommended to mitigate bronchoconstriction when airway instrumentation is required.

Administration, Inhalation↗
PubMed2000

A comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children.

UNLABELLED: We examined changes in the cardiorespiratory system of small children during surgical correction of strabismus with a laryngeal mask airway and spontaneous respiration with sevoflurane or halothane inhaled anesthesia. Fifty-one children, 1-7 yr old, having outpatient strabismus correction were randomized to sevoflurane (S) or halothane (H) in 66% nitrous oxide at 1.3 minimum alveolar concentration. Children breathed spontaneously through a laryngeal mask airway and were not pretreated with anticholinergics. The oculocardiac reflex (OCR), defined as a 20% decrease in heart rate (HR) from baseline, dysrhythmias, or sinoatrial arrest concomitant with ocular muscle traction occurred less frequently with sevoflurane than with halothane (S 38%, H79%, P = 0.009). The baseline HR was higher with sevoflurane (S 114 +/- 13 bpm, H 101 +/- 15 bpm, P = 0.002). The lowest HR occurred with halothane (S 95 +/- 22 bpm, H 73 +/- 19 bpm, P = 0.001). The incidence of dysrhythmias was higher in the halothane group (S 4%, H 42%, P = 0.004). Reductions in minute ventilation and PETCO(2) accompanied OCRs. Airway irritability was present with halothane only (S 0, H 3). Eleven children, of whom the majority had received halothane, required measures to correct SpO(2) < 95% or PETCO(2) > 60 mm Hg during maintenance anesthesia (S 11%, H 32%). Sevoflurane may be a more suitable anesthetic than halothane for operations involving traction on the ocular muscles with spontaneous respiration in children because of reduced incidence of OCR, airway irritability, and ventilatory disturbances. IMPLICATIONS: Some children experience a sudden slowing of the heart and impaired breathing when the surgeon pulls on the eye muscles during squint operations under anesthesia. Sevoflurane, a recently developed anesthetic vapor, may reduce this problem when compared with the established vapor halothane.

Anesthesia, Inhalation↗
PubMed1990

Postoperative apnea in former preterm infants: prospective comparison of spinal and general anesthesia.

Thirty-six former preterm infants undergoing inguinal hernia repair were studied. All were less than or equal to 51 weeks postconceptual age at the time of operation. Patients were randomly assigned to receive general or spinal anesthesia. Group 1 patients received general inhalational anesthesia with neuromuscular blockade. Group 2 patients received spinal anesthesia using 1% tetracaine 0.4-0.6 mg/kg in conjunction with an equal volume of 10% dextrose and 0.02 ml epinephrine 1:1000. In the first part of the study, infants randomized to receive spinal anesthesia also received sedation with im ketamine 1-2 mg/kg prior to placement of the spinal anesthetic (group 2 A). The remainder of group 2 patients did not receive sedation (group 2 B). Respiratory pattern and heart rate were monitored using an impedance pneumograph for at least 12 h postoperatively. Tracings were analyzed for evidence of apnea, periodic breathing and/or bradycardia by a pulmonologist unaware of the anesthetic technique utilized. None of the patients who received spinal anesthesia without ketamine sedation developed postoperative bradycardia, prolonged apnea, or periodic breathing. Eight of nine infants (89%) who received spinal anesthesia and adjunct intraoperative sedation with ketamine developed prolonged apnea with bradycardia. Two of the eight infants had no prior history of apnea. Five of the 16 patients (31%) who received general anesthesia developed prolonged apnea with bradycardia. Two of these five infants had no prior history of apnea. When infants with no prior history of apnea were analyzed separately, there was no statistically significant increased incidence of apnea in children receiving general versus spinal anesthesia with or without ketamine sedation. Because of the small numbers of patients studied, and the multiple factors that may influence the incidence of postoperative apnea (e.g., prior history of neonatal apnea), standard postoperative respiratory monitoring of these high-risk infants is still recommended following all anesthetic techniques.

Anesthesia, General↗
PubMedDate not supplied

Gas exchange during xylazine-ketamine anesthesia in neonatal calves.

Ten neonatal calves were anesthetized with xylazine and ketamine intramuscularly and breathed air spontaneously. Drug injection was repeated after 45 minutes. Each injection resulted in a rapid and sustained increase in respiratory rate, but arterial carbon dioxide tension (PaCO2) increased, indicating hypoventilation. Arterial hypoxemia, primarily caused by hypoventilation, developed within 15 minutes of each injection, but gradually disappeared. Acidemia was primarily respiratory in origin. Heart rate and arterial blood pressure decreased for the duration of anesthesia (90 minutes). This form of anesthesia is a satisfactory alternative to inhalation anesthesia of neonatal calves.

Anesthesia, General↗
PubMed2001

[The memory of tracheal extubation during emergence from general anesthesia].

The authors evaluated the memory of tracheal extubation during emergence from general anesthesia. We screened 3,039 consecutive patients undergoing elective surgery from November 1, 1998 to December 31, 1999. Of 3,039 patients, 1,993 were interviewed postoperatively at the anesthesia clinic and 202 had the memory of tracheal extubation. The incidence was higher in the groups of female, younger and propofol anesthesia compared to male, elder and inhalational anesthesia, respectively. The patients who were dissatisfied with anesthesia were more in the patients with the memory of tracheal extubation compared to the patients without the memory. We consider that the memory of tracheal extubation contributes to the dissatisfaction with anesthesia.

Adolescent↗
PubMed2002

Cerebrospinal fluid centesis at the cerebellomedullary cistern of kittens.

We needed an effective technique for obtaining cerebrospinal fluid (CSF) from young (2- to 18-week-old) kittens. Standard veterinary technique was not suitable, so we adapted a previously published technique for rats. We first established an effective isoflurane-only anesthetic protocol for young kittens. After inhalant anesthesia, the kittens were positioned on a supporting platform to gain flexion of the head and neck. A micromanipulator was used to hold and slowly advance the collection needle. At the time this report was written, we had collected a total of 33 samples from eight kittens without causing apparent neurologic deficits. Correct positioning of the animal and collection needle was critical for success. This procedure enabled the collection of approximately 0.5 ml CSF from kittens younger than 12 weeks and larger volumes from older kittens.

Age Factors↗
PubMed2004

Field use of isoflurane and air anesthetic equipment in wildlife.

Conventional inhalation anesthesia of wildlife species within natural habitats presents significant practical problems. Heavy cylinders of medical grade oxygen are often unavailable in field situations. Equipment has been modified to permit the delivery of isoflurane in ambient air as the carrier and to be fitted with circuitry adaptable for different species and anesthetic situations. Preliminary empirical studies at low altitude in a range of small mammalian and avian species demonstrate the suitability of this combination and these techniques for inducing and maintaining anesthesia in clinically normal patients undergoing relatively minor procedures. The equipment has also been used to deepen and prolong anesthesia in several larger species, including great apes and large cats, after induction with injectable agents. These techniques, in combination with pulse oximetry to detect hypoxemia, provide a cheap, robust, and portable inhalation anesthetic system for field situations that is not dependent on compressed gasses.

Anesthesia, Inhalation↗
PubMed2001

Surgeon's occupational exposure to nitrous oxide and sevoflurane during pediatric surgery.

Health hazards from occupational exposure to trace concentrations of anaesthetic gases cannot be definitively excluded. The aim of the study was to determine the surgeon's occupational exposure to nitrous oxide and sevoflurane during pediatric surgical procedures. Twenty young children (age < 10 years) and five teenagers (age > 10 years) underwent elective abdominal surgery under general inhalational anesthesia. The operating room was equipped with modern air conditioning and waste anesthetic gas scavenger. Levels of both nitrous oxide and sevoflurane were determined in the breathing zone of the surgeon and the anesthesiologist during the operative procedures by means of a direct-reading photoacoustic infrared spectrometer. Both the surgeon and the anesthesiologist were exposed to low concentrations of the inhalational agents used. Exposure to sevoflurane and nitrous oxide was clearly higher during surgery in young children than during operative procedures in teenagers. Nonetheless, the concentrations of these agents were well below the threshold limits of 25 ppm for nitrous oxide and 2 ppm for sevoflurane recommended by the National Institute of Occupational Safety and Health. General anesthesia results in operating room air pollution with inhalational anesthetics. Under modern air conditioning, personnel's occupational exposure is low, and inhalational anesthesia is safe from the standpoint of modern workplace laws and health care regulations. Nonetheless, all efforts must be taken to maintain occupational exposure at this low level.

Abdomen↗
PubMed1997

Positron emission tomography study of regional cerebral metabolism in humans during isoflurane anesthesia.

BACKGROUND: Although the anesthetic effects of the intravenous anesthetic agent propofol have been studied in the living human brain using brain imaging technology, the nature of the anesthetic state evident in the human brain during inhalational anesthesia remains unknown. To examine this issue, the authors studied the effects of isoflurane anesthesia on human cerebral glucose metabolism using positron emission tomography (PET). METHODS: Five volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism and the other scan assessed metabolism during isoflurane anesthesia titrated to the point of unresponsiveness (means +/- SD; expired = 0.5 +/- 0.1%). Scans were obtained with a GE2048 scanner (4.5-mm resolution-FWHM) using the 18fluorodeoxyglucose technique. RESULTS: Awake whole-brain glucose metabolism averaged 6.9 +/- 1.5 mg.100 g-1.min-1 (means +/- SD). Isoflurane reduced whole-brain metabolism 46 +/- 11% to 3.6 +/- 0.3 mg.100 g-1.min-1 (P < or = 0.005). Regional metabolism decreased fairly uniformly throughout the brain, and no evidence of any regional metabolic increases were found in any brain region for any participant. A region-of-interest analysis showed that the pattern of regional metabolism evident during isoflurane anesthesia was not significantly different from that seen when participants were awake. CONCLUSION: These data clarify that the anesthetic state evident in the living human brain during unresponsiveness induced with isoflurane is associated with a global, fairly uniform, whole-brain glucose metabolic reduction of 46 +/- 11%.

Adult↗
PubMed2002

Effects of carprofen on renal function and results of serum biochemical and hematologic analyses in anesthetized dogs that had low blood pressure during anesthesia.

OBJECTIVE: To investigate effects of IV administered carprofen on indices of renal function and results of serum biochemical and hematologic analyses in dogs anesthetized with acepromazine-thiopentone-isoflurane that had low blood pressure during anesthesia. ANIMALS: 6 healthy Beagles. PROCEDURE: A randomized crossover study was conducted, using the following treatments: saline (0.9% NaCl solution)-saline, saline-carprofen, and carprofen-saline. Saline (0.08 ml/kg) and carprofen (4 mg/kg) were administered IV. The first treatment was administered 30 minutes before induction of anesthesia and immediately before administration of acepromazine (0.1 mg/kg, IM). Anesthesia was induced with thiopentone (25 mg/ml, IV) and maintained with inspired isoflurane (2% in oxygen). The second treatment was administered 30 minutes after onset of inhalation anesthesia. Blood gases, circulation, and ventilation were monitored. Renal function was assessed by glomerular filtration rate (GFR), using scintigraphy, serum biochemical analyses, and urinalysis. Hematologic analysis was performed. Statistical analysis was conducted, using ANOVA or Friedman ANOVA. RESULTS: Values did not differ significantly among the 3 treatments. For all treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses, a decrease in mean arterial blood pressure to 65 mm Hg, an increase of 115 pmol/L in angiotensin II concentration, and an increase of 100 seconds in time required to reach maximum activity counts during scintigraphy. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen administered IV before or during anesthesia did not cause detectable significant adverse effects on renal function or results of serum biochemical and hematologic analyses in healthy Beagles with low blood pressure during anesthesia.

Acepromazine↗
PubMed1996

A comparison of the effects of propofol-alfentanil versus isoflurane anesthesia on arterial oxygenation during one-lung ventilation.

OBJECTIVE: To determine whether intravenous propofol-alfentanil anesthesia provides superior arterial oxygenation (Pao2) during one-lung ventilation (OLV) compared with isoflurane inhalation anesthesia. DESIGN: A prospective, randomized, cross-over study. SETTING: Tertiary-care university hospital. PARTICIPANTS: Thirty adults having either thoracoscopic pulmonary surgery or esophageal surgery. INTERVENTIONS: Patients received either propofol-alfentanil infusion anesthesia or one minimum alveolar concentration (MAC) of isoflurane during the initial period of two-lung ventilation and the first 30 minutes of OLV and then were switched to the other anesthetic for the duration of OLV. MEASUREMENTS AND MAIN RESULTS: Arterial blood gases and hemodynamics were recorded during two-lung ventilation and after 20 and 30 minutes of OLV with each anesthetic technique. The mean values (+/- SD) for Pao2 during propofol-alfentanil anesthesia after 20 minutes (222 +/- 100) and 30 minutes (228 +/- 102 mmHg) of one-lung ventilation were not significantly different than after 20 minutes (213 +/- 99) or 30 minutes (214 +/- 96 mmHg) of isoflurane; beta error less than 0.1. Mean heart rate was lower during intravenous (78 +/- 15 min) than inhalation (85 +/- 17 min) anesthesia (rho = 0.03). CONCLUSION: This study does not support the theory that total intravenous anesthesia will decrease the risk of hypoxemia during OLV.

Adult↗
PubMed2004

Continuous measurement of gas uptake and elimination in anesthetized patients using an extractable marker gas.

Measurement of pulmonary gas uptake and elimination is often performed, using nitrogen as marker gas to measure gas flow, by applying the Haldane transformation. Because of the inability to measure nitrogen with conventional equipment, measurement is difficult during inhalational anesthesia. A new method is described, which is compatible with any inspired gas mixture, in which fresh gas and exhaust gas flows are measured using carbon dioxide as an extractable marker gas. A system was tested in eight patients undergoing colonic surgery for automated measurement of uptake of oxygen, nitrous oxide, isoflurane, and elimination of carbon dioxide with this method. Its accuracy and precision were compared with simultaneous measurements made with the Haldane transformation and corrected for predicted nitrogen excretion by the lungs. Good agreement was obtained for measurement of uptake or elimination of all gases studied. Mean bias was -0.003 l/min for both oxygen and nitrous oxide uptake, -0.0002 l/min for isoflurane uptake, and 0.003 l/min for carbon dioxide elimination. Limits of agreement lay within 30% of the mean uptake rate for nitrous oxide, within 15% for oxygen, within 10% for isoflurane, and within 5% for carbon dioxide. The extractable marker gas method allows accurate and continuous measurement of gas uptake and elimination in an anesthetic breathing system with any inspired gas mixture.

Administration, Inhalation↗
PubMed1990

Anesthesia for angioembolization of brain arteriovenous malformations: a retrospective assessment.

We reviewed the anesthetic management of 55 patients under 18 years of age during angioembolization of arteriovenous malformations. Patients were grouped according to age: less than 1 month (A), 1-11 months (B), 1-5 years (C) and 7-13 years (D). All had general endotracheal anesthesia. In groups A and B, approximately 43% received pure narcotic and 43% balanced while only 14% had pure inhalational anesthesia. In groups C and D, 41 and 52% received pure inhalation and balanced anesthesia, respectively, while only 7% had pure narcotics. Hypotension was induced in 50% (C and D) and in 20% (A and B) of the patients. Intraoperative lasix or phlebotomy was used in 28, 16, 13 and 0% of groups A, B, C and D, respectively. Two arrests occurred immediately after the injection of the embolizing material. From our review, no single type of anesthesia can be advocated over all others. The use of invasive monitoring (arterial and central venous lines), precise fluid management and the avoidance of nitrous oxide will help to decrease the incidence of intraoperative complications during anesthesia.

Anesthesia, General↗
PubMedDate not supplied

Thoracoscopy as a nonpharmacotherapeutic research modification for limiting postoperative chest pain.

Diminished tissue injury and shortened clinical recovery are benefits of using an endoscopic approach for patients needing operative procedure. In the course of developing an experimental model requiring procurement of topographically precise lung biopsy specimens, we sought to apply thoracoscopy as a research alternative to thoracotomy. In addition, we investigated the influence of thoracoscopy on postprocedure recovery practices using rabbits divided into four treatment groups. Rabbit groups 1 and 2 underwent thoracoscopy and lung biopsy while maintained by one-lung anesthesia. Additionally, group 2 had ketoprofen and bupivacaine HCl analgesics injected for treatment during postprocedure recovery. These two groups were compared to control rabbits in groups 3 and 4, which underwent inhalant anesthesia without thoracoscopy. Control group 3 also received the injection analgesic combination. During recovery, rabbit behavior was systematically assessed for evidence of pain. No behavior considered indicative of pain needing intervention was observed regardless of treatment group. Limited changes in plasma corticosterone, catecholamines, and prostaglandin E2 levels measured during recovery were difficult to associate with any treatment. Unexpectedly, significantly different mean corticosterone and catecholamines levels were detected in rabbits given the injection analgesic combination in the absence of thoracoscopic procedure, as compared to other treatment groups. The results highlight the importance of awareness that analgesic drug administration has the potential to alter homeostasis and affect interpretation of some study findings by its own guise. Correlation of the mean pain study results with plasma biochemical data supports preferential use of thoracoscopy as a refinement for limiting postprocedural pain in research models.

Anesthesia, Inhalation↗