A threshold of 100 or more colony-forming units on the anesthesia machine predicts bacterial pathogen detection: a retrospective laboratory-based analysis.

PURPOSE: Preventing the spread of pathogens in the anesthesia work area reduces surgical site infections. Improved cleaning reduces the percentage of anesthesia machine samples with ≥ 100 colony-forming units (CFU) per surface area sampled. Targeting a threshold of < 100 CFU when cleaning anesthesia machines may be associated with a lower prevalence of bacterial pathogens. We hypothesized that anesthesia work area reservoir samples returning < 100 CFU would have a low (< 5%) prevalence of pathogens. METHODS: In this retrospective cohort study of bacterial count data from nine hospitals, obtained between 2017 and 2022, anesthesia attending and assistants' hands, patient skin sites (nares, axilla, and groin), and anesthesia machine (adjustable pressure-limiting valve and agent dials) reservoirs were sampled at case start and at case end. The patient intravenous stopcock set was sampled at case end. The isolation of ≥ 1 CFU of Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Enterococcus, vancomycin-resistant Enterococcus, gram-negative (i.e., Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter spp.) or coagulase-negative Staphylococcus was compared for reservoir samples returning ≥ 100 CFU vs those returning < 100 CFU. RESULTS: Bacterial pathogens were isolated from 24% (7,601/31,783) of reservoir samples, 93% (98/105) of operating rooms, and 83% (2,170/2,616) of cases. The ratio of total pathogen isolates to total CFU was < 0.0003%. Anesthesia machine reservoirs returned ≥ 100 CFU for 44% (2,262/5,150) of cases. Twenty-three percent of samples returning ≥ 100 CFU were positive for ≥ 1 bacterial pathogen (521/2,262; 99% lower confidence limit, 22%) vs 3% of samples returning < 100 CFU (96/2,888; 99% upper limit, 4%). CONCLUSIONS: Anesthesia machine reservoir samples returning < 100 CFU were associated with negligible pathogen detection. This threshold can be used for assessment of terminal, routine, and between-case cleaning of the anesthesia machine and equipment. Such feedback may be useful because the 44% prevalence of ≥ 100 CFU was comparable to the 46% (25/54) reported earlier from an unrelated hospital.

RéSUMé: OBJECTIF: La prévention de la propagation des agents pathogènes dans la zone de travail de l'anesthésie réduit les infections du site opératoire. L'amélioration du nettoyage réduit le pourcentage d'échantillons de l'appareil d'anesthésie présentant ≥ 100 unités de formation de colonie (UFC) par surface échantillonnée. Le fait de cibler un seuil < 100 UFC lors du nettoyage des appareils d'anesthésie pourrait être associé à une prévalence plus faible d'agents pathogènes bactériens. Nous avons émis l'hypothèse que les échantillons des réservoirs de la zone de travail d'anesthésie < 100 UFC résulteraient en une faible prévalence (< 5 %) d'agents pathogènes. MéTHODE: Dans cette étude de cohorte rétrospective des données de décompte bactérien de neuf hôpitaux, obtenues entre 2017 et 2022, les mains des anesthésiologistes et des assistant·es en anesthésie, les sites cutanés des patient·es (narines, aisselles et aines) et les réservoirs de l'appareil d'anesthésie (soupape de réglage de limitation de pression et cadrans d'agent) ont été échantillonnés au début et à la fin de chaque cas. Les échantillons sur l'ensemble de robinets d'arrêt intraveineux des patient·es ont été prélevés à la fin de chaque cas. L'isolement de ≥ 1 UFC de staphylocoque doré, de staphylocoque doré résistant à la méthicilline, d'entérocoque, d'entérocoque résistant à la vancomycine, de staphylocoque à Gram négatif (c.-à-d. Klebsiella, Acinetobacter, Pseudomonas et Enterobacter spp.) ou à coagulase négative a été comparé pour les échantillons de réservoir retournant ≥ 100 UFC vs ceux qui comportaient < 100 UFC. RéSULTATS: Des bactéries pathogènes ont été isolées dans 24 % (7601/31 783) des échantillons de réservoir, 93 % (98/105) des salles d'opération et 83 % (2170/2616) des cas. Le rapport entre le nombre total d'isolats d'agents pathogènes et le nombre total d'UFC était de < 0,0003 %. Les échantillons pris sur les réservoirs d'appareils d'anesthésie ont retourné ≥ 100 UFC dans 44 % (2262/5150) des cas. Vingt-trois pour cent des échantillons retournés ≥ 100 UFC étaient positifs pour ≥ 1 agent pathogène bactérien (521/2262; limite de confiance inférieure à 99 %, 22 %) vs 3 % des échantillons retournant < 100 UFC (96/2888 ; 99 % de la limite supérieure, 4 %). CONCLUSION: Les échantillons pris sur les réservoirs de l'appareil d'anesthésie comportant < 100 UFC étaient associés à une détection négligeable d'agents pathogènes. Ce seuil peut être utilisé pour l'évaluation du nettoyage final, de routine et entre les cas de l'appareil et de l'équipement d'anesthésie. Une telle rétroaction peut être utile parce que la prévalence de 44 % de ≥ 100 UFC était comparable aux 46 % (25/54) rapportés précédemment dans un autre hôpital.

Anesthesiologist behavior and anesthesia machine use in the operating room during the COVID-19 pandemic: awareness and changes to cope with the risk of infection transmission.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease [coronavirus disease 2019 (COVID-19) infection] first appeared in December 2019 in China and is now spreading worldwide. Because SARS-CoV-2 can be transmitted via aerosols and surface contaminations of the environment, appropriate use of anesthesia machines and appropriate behavior in the operation room (OR) are required specifically in relation to this disease. The use of high-performance hydrophobic filters with a high rate of virus rejection is recommended as the type of viral filter, and surgical team behaviors that result in aerosol splashes should be avoided. Appropriate hand hygiene by the anesthesiologist is crucial to prevent unexpected environmental contamination. When the anesthesia machine is used instead of an intensive care unit ventilator, it is important to keep the fresh gas flow at least equal to the minute ventilation to prevent excessive humidity in the circuit and to monitor condensation in the circuit and inspiratory carbon dioxide pressure. In addition, both the surgical smoke inherent in thermal tissue destruction and the surgical team's shoe soles may be factors for the presence of SARS-CoV-2 in the operating room. Ensuring social distancing-even with a mask in the OR-may be beneficial because healthcare providers may be asymptomatic carriers. After the acute crisis period of COVID-19, the number of cases of essential but nonurgent surgeries for waiting patients is likely to increase; therefore, optimization of OR scheduling will be an important topic. Anesthesiologists will benefit from new standard practices focusing on the prevention of COVID-19 infection.

Determinación de peep clínicamente útil en los ventiladores de las modernas máquinas de anestesia / Determination of peep clinically usefull in the ventilators of the modern anesthesia machines

El desarrollo tecnológico permitió incorporar a los ventiladores de las nuevas máquinas de anestesia la posibilidad de brindar presión positiva al final de la espiración (PEEP) electrónica junto con modos ventilatorios, así como curvas de presión /volumen y flujo/ volumen. El objetivo del estudio fue encontrar el valor de PEEP de cada uno de los pacientes, buscando aquel que se acompañara del aumento más significativo de la compliance pulmonar estática. Se analizaron 20 pacientes con una edad promedio de 66, peso promedio de 77 kg, sometidos a cirugía cardíaca con circulación extracorpórea. Se utilizó un patrón ventilatorio con ventilación controlada por volumen, con una onda de flujo inspiratorio cuadrada y una pausa inspiratoria del 30%; con un volumen corriente de 7 ml/kg de peso; FiO2 de 0.6; y una relación inspiración/espiración 1:2. Se realizaron maniobras manuales de reclutamiento pulmonar seriadas y, luego de cinco minutos de una ventilación sin PEEP con un flujo de gas fresco de 2 l/min, se procedió a medir en ese momento la compliance estática, el valor de presión de vía aérea en el punto de inflexión y en el punto de máxima curvatura de la parte inspiratoria y espiratoria de la curva de presión/volumen respectivamente...

The technological development has allowed us to incorporated electronic positive end-expiratory pressure (PEEP) to the new anesthesia machines, as well as different ventilation modes and curves of pressure/volume and flow/volume. The aim of this study was to find the best value of PEEP of each patient, that determined the most significative increase of the pulmonary static compliance. 20 patients were analyzed, 66 years old average and 77 kg of weight, scheduled for cardiac surgery with extracorporeal circulation. The ventilatory pattern used was : controlled ventilation with a square wave of inspiratory flow, inspiratory pause of 30%, tidal volume of 7 ml/kg, inspired fraction of oxygen of 0.6 and inspiration/espiration relation: 1:2. Serial manual maneuvers of recruitment were done, and after 5 minutes with a fresh gas flow of 2 l/min the following observations and calculations were made: static pulmonary compliance, airway pressure at the point of flexion and at the point of maximum curvature of the inspiratory and espiratory part of the curve pressure/ volume respectively...

O desenvolvimento tecnológico tem permitido incorporar aos ventiladores dos novos equipamentos de anestesia a possibilidade de usar PEEP eletrônica junto com modos ventilatórios e análise das curvas de pressão-volume e fluxo-volume. Nosso objetivo foi encontrar o melhor valor de PEEP de cada um des pacientes, buscando aquele valor de PEEP que se acompanhe do aumento mais significativo da complacência pulmonar estática. Foram analisados 20 pacientes com idade média de 66 anos, peso médio de 77 quilos, submetidos a cirurgia cardíaca com circulação extra-corpórea. Naqueles em que se utiliza um padrão ventilatório em ventilação controlada por volume, com uma onda de fluxo inspiratório quadrada e uma pausa inspiratória de 30%, com um volume corrente de 7ml/kg de peso, FiO2 =0,6, relação inspiração/expiração 1:2.Com a utilização de manobras manuais de recrutamento pulmonar seriadas, aos quais logo após 5 min de uma ventilação sem PEEP com um fluxo de gáz fresco de 2l/min, comessa-se a medir nesse momento a complacência estática, o valor de pressao de via aérea no ponto de inflexão e no ponto de máxima curvatura da parte inspiratória e expiratória da curva de pressão/volume respectivamente.

SARACAP Monitoring of Anesthesia Machines during Anesthesia / 대한마취과학회지

With recent rise in medico-legal problems, there is also an increase in number of problems involved with anesthesia. Major causes of anesthetic accident are malfunctioning anesthetic machine and inappropriate gas flow and concentration of anesthetic gas, resulting from malfunctioning ventilatory circuit. Therefore, anesthesiologist needs an apparatus to determine the appropriateness of ventilation and a monitoring system to measure a concentration of inspired O2 and inhalation anesthetics. To prevent circulatory and respiratory abnormalities and to promote the safty during anesthesia, we used the SARA monitoring system, as an indicator of safty measure. We monitored the anesthesia machines (n=17), using in operating room in Shinchon Severance hospital, by using the SARA monitoring system which was connected to the distal portion of endotracheal tube. We intended to analysis the relationships between anesthetic machines, vaporizers, ventilators and parameters measured form each machine, in clinical use. The results were as follows; 1) Average used year of anesthesia machines was 7.7 years, that of vaporizers was 7.6 years and that of ventilator's was 4.0 years. 2) When vaporizers dial was fixed at enflurane 2.0%, average measured-FiEnf was 2.02+/-0.22%, equal to dial setting and average FiEnf was 1.70+/-0.25%, usually lower than dial setting. 3) In some anesthesia machines, CO2 rebreathing occured always during ansthesia and FiEnf & FeEnf were decreased in case of CO2 rebreathing. 4) FiEnf by vaporizers was decreased as following orders, Draeger, Ohio and Cyprene.