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The first anesthetic machines appeared following their public demonstration by Morton in 1846. These initial devices were simple inhalers based on the evaporation of the anesthetic agent. Their main problem was the loss of effectiveness with cooling. More complex inhalers were subsequently developed, in which the main difference was the possibility to provide more than one agent. Moreover, the concentration of the inhaled anesthetic was regulated for greater efficiency. At the beginning of the twentieth century, gas machines emerged, allowing the application of an anesthetic flow independent of the patient’s inspiratory effort. These machines incorporated technological advances such as flow meters, carbon dioxide absorption systems and fine adjustment vaporizers. In this period, in the field of thoracic surgery, intraoperative artificial ventilation began to be employed, which helped overcome the problem of pneumothorax associated with open pleura by applying positive pressure. From the 1930s, the gas machines were fitted with a ventilator, and by the 1950s this had become a basic component of the anesthesia system. Later still, in the 1980s, alarm and monitoring systems were incorporated, giving rise to the current generation of workstations.

The objective of this retrospective study was to review the results of a 4-year audit performed on anesthetic machines and vaporizers used in veterinary clinics in Spain and Portugal. Data was collected between July 2016 and April 2020. Inspections were carried out by a team of seven veterinarians, using a human-modified system of checks that was adapted to a veterinary practice. The evaluation of each item was noted as “correct” or “incorrect”. The vaporizers' performance was evaluated using a self-calibrating gas analyzer. The vaporizer was classified as “correct” or “incorrect” when the vaporization error was less than or equal to, or more than 20%, respectively. The anesthetic machine was classified as “conforming” if all its components were noted as “correct” and no leaks were detected, or as “non-conforming” if any of the components was noted as “incorrect” or if a leak was detected. If the inspector was able to repair on-site the item malfunctions detected and the machine was fit for use, they issued a final report as “conforming.” On the contrary, if such malfunctions persisted, the final report was “non-conforming,” and a recommendation to remove the machine from service until its final repair was provided. To perform statistical analysis, each inspected item was used as predictor, classification and regression trees were built, and a random forest analysis was performed. A total of 2,001 anesthetic machines and 2,309 vaporizers were studied. After inspection, 42.7 and 26.4% of the machines were non-conforming and conforming, respectively, whereas 30.9% could be repaired in situ. A total of 27.1% of the isoflurane vaporizers and 35.9% of the sevoflurane vaporizers were incorrect. Machine learning techniques showed that the most important variables in the classification of the anesthetic machines as conforming or non-conforming were mostly the scavenger system and the canister, followed some way behind by the APL valve, source of oxygen, reservoir bag, vaporizer, and connections.

The physicochemical properties of commercial medical sorbents of carbon dioxide (Amsorb Plus, Dräger 800, Dräger free, Loflosorb, Sodasorb, Sofnolime, Spherasorb, Ventisorb, and Russian XPI absorber) are studied. Their chemical composition, textural characteristics, and duration of protection against CO2 are determined, and the mechanical strength and resistance to abrasion are measured for sorbent granules using the Shell SMS-1471 and ASTM D 4058 96 methods. It is found that the Dräger 800 specimen has the best parameters (high CO2 capacity and strength). The obtained data on the performance of commercial sorbents and the recommendations made in this work can be used in medicine, mine rescue services, and fields of science and industry where the problem of purifying air of carbon dioxide mixtures arises. [ABSTRACT FROM AUTHOR]

Background and Objective: Nowadays, medical equipment are daily used for different patients in hospitals. Contamination can be transmitted by anesthetic equipment from one patient to another. The objective of this study was to determine the rate of contamination of anesthetic machine after using cetrimide-C as a disinfectant solution. Methods: In this descriptive and analytical study, 48 samples of the two parts of anesthetic machine were taken in 6 operation rooms of Babol Shahid Beheshti hospital. Sampling from the parts before and after sodalime was taken at the stages before and after washing with cetrimide-C as a disinfectant solution (10%). Data was analyzed by Chi-square test. Findings: According to the results, from where the samples were taken before sodalime at the stage before washing 16.7% of samples and after washing 19.4% contaminated to bacteria. Also, from the parts where the samples were taken after sodalime at the stage before washing 37.5% of cases and after washing 33.3% contaminated by bacteria that there was not statistically significant difference. Conclusion: According to the results, there was a bacterial contamination in the anesthetic machines at the stage before and after washing and it indicates that common method and using cetrimide-C as a disinfectant solution with unstandard concentration are not so effective in the decrease of contamination.

Background: Low inspired oxygen acutely increases pulmonary vascular resistance and decreases pulmonary-systemic blood flow ratio. We present a simple method to lower inspired oxygen fraction (FIO2 < 0.21) without supplemental nitrogen, during mechanical ventilation by an anesthesia machine. Methods: After institutional approval, seven healthy adult volunteers and three infants (0–12 month old) scheduled for congenital heart surgery were enrolled in this study. All the infants were diagnosed with congestive heart failure because of high pulmonary blood flow and were thought to benefit from low FIO2. The volunteers performed spontaneous ventilation (fresh air flow rate = 10 l·min−1, tidal volume = 600 ml, frequency = 10 br·min−1). The infants were mechanically ventilated with air (fresh air flow rate = 6 l·min−1, tidal volume = 10 ml·kg−1, 15 < frequency < 30 br·min−1 to adjust PaCO2 between 5.8 kPa and 6.5 kPa (45–50 mmHg), after induction of general anesthesia and tracheal intubation. The fresh gas flow rates were determined by the following formula. Fresh gas flow rate = (FIO2 − FEO2) EVE/(0.21 + FIO2 − FEO2 − target FIO2). We recorded FIO2 every 5 min for 30 min. When arterial oxygen saturation decreased >15%, fresh gas flow rates were increased to adjust FIO2 to 0.21. Results: In all of the seven volunteers and three infants target FIO2 was achieved in <10 min. FIO2 was kept at 0.18 ± 0.01 (SD) by calculated fresh air flow rates. In one infant, SpO2 decreased >15% 20 min after lowering FIO2, we had to discontinue this study, and increase fresh gas flow to ventilate the infant with FIO2 0.21. In the other two infants, FIO2 was maintained throughout the study. Conclusions: This simple and convenient method to decrease FIO2, has a utility in clinical situations, in which pulmonary vascular resistance is to be increased to improve systemic oxygen delivery in patients with high pulmonary blood flow during cardiac surgery. [ABSTRACT FROM AUTHOR]

The use of low-flow anesthesia causes a discrepancy between the delivered fraction (FD) and the inspired fraction (FI) of inhaled gases. We compared the FI/FD ratios of a new circle (fresh gas inlet located between the inspiratory valve and the patient) to those of the conventional circle (fresh gas inlet located between the inspiratory valve and the CO2 absorber) in low-flow isoflurane and sevoflurane anesthesia, using three anesthetic machines (Dräger NM-GS, Dräger Fabius-GS, and ACOMA KMA-1300-III). Eighty-two patients were randomly assigned to three experimental groups. For experiment 1, 32 patients were allocated to the NM-GS conventional/new, NM-GS new/conventional, ACOMA conventional/new, and ACOMA new/conventional groups. For experiment 2, 14 patients were allocated to ACOMA conventional/conventional and ACOMA new/new groups to measure isoflurane FI/FD ratios. For experiment 3, 36 patients were allocated to ACOMA conventional/conventional, ACOMA new/new, Fabius conventional/conventional, and Fabius new/new to measure sevoflurane FI/FD ratios. In experiment 1, the NM-GS showed no significant changes in the FI/FD ratios. However, in the ACOMA, the new circle improved the FI/FD ratio. In experiment 2, the isoflurane FI/FD ratios in the new circle of the ACOMA were significantly higher than those in the conventional circle. In experiment 3, the sevoflurane FI/FD ratios in the new circle of both the ACOMA and the Fabius were significantly higher than those in the conventional circles. The positioning of the fresh gas inlet between the inspiratory valve and the patient improved the FI/FD ratios of both isoflurane and sevoflurane during low-flow anesthesia in two decoupling-style anesthetic machines (ACOMA and Fabius). [ABSTRACT FROM AUTHOR]

The first anesthetic machines appeared following their public demonstration by Morton in 1846. These initial devices were simple inhalers based on the evaporation of the anesthetic agent. Their main problem was the loss of effectiveness with cooling. More complex inhalers were subsequently developed, in which the main difference was the possibility to provide more than one agent. Moreover, the concentration of the inhaled anesthetic was regulated for greater efficiency. At the beginning of the twentieth century, gas machines emerged, allowing the application of an anesthetic flow independent of the patient's inspiratory effort. These machines incorporated technological advances such as flow meters, carbon dioxide absorption systems and fine adjustment vaporizers. In this period, in the field of thoracic surgery, intraoperative artificial ventilation began to be employed, which helped overcome the problem of pneumothorax associated with open pleura by applying positive pressure. From the 1930s, the gas machines were fitted with a ventilator, and by the 1950s this had become a basic component of the anesthesia system. Later still, in the 1980s, alarm and monitoring systems were incorporated, giving rise to the current generation of workstations., (Copyright © 2021 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.)

The objective of this retrospective study was to review the results of a 4-year audit performed on anesthetic machines and vaporizers used in veterinary clinics in Spain and Portugal. Data was collected between July 2016 and April 2020. Inspections were carried out by a team of seven veterinarians, using a human-modified system of checks that was adapted to a veterinary practice. The evaluation of each item was noted as "correct" or "incorrect". The vaporizers' performance was evaluated using a self-calibrating gas analyzer. The vaporizer was classified as "correct" or "incorrect" when the vaporization error was less than or equal to, or more than 20%, respectively. The anesthetic machine was classified as "conforming" if all its components were noted as "correct" and no leaks were detected, or as "non-conforming" if any of the components was noted as "incorrect" or if a leak was detected. If the inspector was able to repair on-site the item malfunctions detected and the machine was fit for use, they issued a final report as "conforming." On the contrary, if such malfunctions persisted, the final report was "non-conforming," and a recommendation to remove the machine from service until its final repair was provided. To perform statistical analysis, each inspected item was used as predictor, classification and regression trees were built, and a random forest analysis was performed. A total of 2,001 anesthetic machines and 2,309 vaporizers were studied. After inspection, 42.7 and 26.4% of the machines were non-conforming and conforming, respectively, whereas 30.9% could be repaired in situ . A total of 27.1% of the isoflurane vaporizers and 35.9% of the sevoflurane vaporizers were incorrect. Machine learning techniques showed that the most important variables in the classification of the anesthetic machines as conforming or non-conforming were mostly the scavenger system and the canister, followed some way behind by the APL valve, source of oxygen, reservoir bag, vaporizer, and connections., Competing Interests: The authors declare that this study received funding from Ecuphar Veterinaria SLU and Belphar Lda. The funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. The handling editor declared a past co-authorship with one of the authors JR., (Copyright © 2020 Redondo, Domenech, Mateu, Bañeres, Martínez and Lopes.)

Introduction: Xenon, due to its interesting anesthetic properties, could improve the quality of anesthesia protocols in horses despite its high price. This study aimed to modify and test an anesthesia machine capable of delivering xenon to a horse., Materials and Methods: An equine anesthesia machine (Tafonius, Vetronic Services Ltd., UK) was modified by including a T-connector in the valve block to introduce xenon, so that the xenon was pushed into the machine cylinder by the expired gases. A xenon analyzer was connected to the expiratory limb of the patient circuit. The operation of the machine was modeled and experimentally tested for denitrogenation, wash-in, and maintenance phases. The system was considered to consist of two compartments, one being the horse's lungs, the other being the machine cylinder and circuit. A 15-year-old, 514-kg, healthy gelding horse was anesthetized for 70 min using acepromazine, romifidine, morphine, diazepam, and ketamine. Anesthesia was maintained with xenon and oxygen, co-administered with lidocaine. Ventilation was controlled. Cardiorespiratory variables, expired fraction of xenon (FeXe), blood gases were measured and xenon was detected in plasma. Recovery was unassisted and recorded., Results: FeXe remained around 65%, using a xenon total volume of 250 L. Five additional boli of ketamine were required to maintain anesthesia. PaO 2 was 45 ± 1 mmHg. The recovery was calm. Xenon was detected in blood during the entire administration time., Conclusion: This pilot study describes how to deliver xenon to a horse. Although many technical problems were encountered, their correction could guide future endeavors to study the use of xenon in horses.