Temperature Outcomes without heater cooler units in adult patients supported with extracorporeal membrane oxygenation: A retrospective cohort study.

INTRODUCTION: Heater-cooler units (HCUs) are frequently incorporated into extracorporeal membrane oxygenation (ECMO) circuits to help maintain patient normothermia. However, these devices may be associated with increased cost and infection risk. This study describes our institution's experience managing adult ECMO patients without the routine use of in-circuit HCUs. METHODS: We performed a retrospective analysis of adult patients treated with veno-venous (VV) or veno-arterial (VA) ECMO at our institution. The primary outcomes were rates of HCU use and the relative duration of the ECMO treatment course in which patients maintained normothermia (36-37.5°C), with and without HCUs. Secondary outcomes of mortality and ECMO-related complications were planned across HCU and non-HCU groups; exploratory analyses were performed across a 75% "ECMO time in normothermia" threshold. RESULTS: Among a cohort of 71 patients, zero (0%) were managed with in-circuit HCUs. A majority of ECMO patient-hours were spent in the normothermic range. Median and mean percentages of ECMO normothermia time were 75% (IQR 49%-81%) and 62% (SD ± 27%). Twenty-nine patients (40%) met the threshold of 75% ECMO normothermia time, as used to evaluate secondary outcomes. At this threshold, mortality risk was significantly higher among the non-normothermic cohort; other ECMO-related complications did not vary significantly. CONCLUSIONS: In the absence of HCU use, the majority of ECMO patient-hours were spent in normothermia. However, only a minority of patients achieved normothermia for at least 75% of their ECMO course. In-circuit HCUs may be required to maintain high percentages of normothermic time in adult EMCO patients.

Mycobacterium chimaera: a report of 2 new cases and literature review.

Mycobacterium chimaera is a non-tuberculous mycobacterium, member of the Mycobacterium avium complex (MAC), which has become a global public health concern due to infection following cardiac surgery performed with contaminated heater-cooler units. M. chimaera infection is characterized by a long latency, non-specific signs and symptoms and high mortality rates. Thus, the diagnosis is still challenging both for forensic pathologists and for clinicians. Clinical manifestations of M. chimaera infection include endocarditis, hepatitis, nephritis, encephalitis and chorioretinitis. A constant histopathologic finding is the presence of non-caseating granulomas, with multinucleated giant cells and histiocytes. Hereby, we present two cases of fatal disseminated M. chimaera infection following aortic valve surgery reporting clinical history and post-mortem findings. Further, we provide a brief overview of the literature with a special focus on histopathological characteristics of M. chimaera infection. The aim of this article is to provide a complete synopsis of histopathological characteristics useful for forensic pathologists.

Detection and decontamination of Mycobacterium chimaera and other non-tuberculosis mycobacteria in heater-cooler devices used in cardiopulmonary bypass: a Manufacturer and National guidelines summary, and a potential resolution to the problem requiring further investigation.

Since 2011, invasive infections due to Mycobacterium chimaera have been diagnosed in patients with previous cardiac surgery. The use of heating/cooling devices (heater-cooler units), necessary to regulate the blood temperature in extra-corporeal circulation, has been identified as a source of contaminated aerosol. Adhering to a strict maintenance program according to the manufacturer's instructions for use including sanitizing is essential to reduce the risk. Current manufacturer guidelines and national recommendations for detection and decontamination of Mycobacterium chimaera and other non-tuberculosis mycobacteria should organically update units' policies and protocols as they are published.

Minimising the risk of Mycobacterium chimaera infection during cardiopulmonary bypass by the removal of heater-cooler units from the operating room.

INTRODUCTION: Mycobacterium chimaera ( M. chimaera) is a recently characterised bacterium that can cause life-threatening infections in small numbers of patients who undergo cardiopulmonary bypass during cardiac surgery. The likely mode of transmission is thought to occur through aerosolisation from contaminated water reservoirs. The airborne bacteria then contaminate the surgical field, leading to an infection months or even years later. The preferred practical solution to disrupt the transmission of these airborne bacteria to the patient is to remove the heater-cooler units (HCUs) from the operating room (OR). We describe a process of achieving this in order to provide information to guide other institutions who wish to do a similar thing. METHODS: A multidisciplinary team was assembled to work on the project. The planning phase involved trialling different OR layouts and simulating the alterations in the HCU circuit function. The changes to the OR were made over a weekend to minimise disruption to the operating schedule. RESULTS: The HCU was moved to the dirty utility room adjacent to the OR. Standard operating procedures (SOP) and risk assessments were made to enable this to be used for a dual purpose. One of the ORs was reconfigured to allow the cardiopulmonary bypass machine to be located close to the HCU in the dirty utility room. The total cost of the alterations was £6,158. Although we have provided a physical barrier to interrupt patient exposure to aerosolised M. chimaera from HCUs, we continue to perform cultures and decontamination as per the national recommendations. The SOP was designed to be auditable to ensure compliance with the protocols. CONCLUSIONS: We show a method by which the HCU can be removed from the OR in a relatively low-cost, straightforward and practical manner.

Reemergence of Mycobacterium chimaera in Heater-Cooler Units despite Intensified Cleaning and Disinfection Protocol.

Invasive Mycobacterium chimaera infections after open-heart surgery have been reported internationally. These devastating infections result from aerosols generated by contaminated heater-cooler units used with extracorporeal circulation during surgery. Despite intensified cleaning and disinfection, surveillance samples from factory-new units acquired during 2014 grew nontuberculous mycobacteria after a median of 174 days.

Transmission of Mycobacterium chimaera from Heater-Cooler Units during Cardiac Surgery despite an Ultraclean Air Ventilation System.

Heater-cooler units (HCUs) were recently identified as a source of Mycobacterium chimaera causing surgical site infections. We investigated transmission of this bacterium from HCUs to the surgical field by using a thermic anemometer and particle counter, videotape of an operating room equipped with an ultraclean laminar airflow ventilation system, and bacterial culture sedimentation plates in a nonventilated room. Smoke from the HCU reached the surgical field in 23 s by merging with ultraclean air. The HCU produced on average 5.2, 139, and 14.8 particles/min in the surgical field at positions Off, On/oriented toward, and On/oriented away, respectively. Culture plates were positive for M. chimaera <5 m from the HCU in the test room. These experiments confirm airborne transmission of M. chimaera aerosols from a contaminated HCU to an open surgical field despite ultraclean air ventilation. Efforts to mitigate infectious risks during surgery should consider contamination from water sources and airflow-generating devices.

Contamination during production of heater-cooler units by Mycobacterium chimaera potential cause for invasive cardiovascular infections: results of an outbreak investigation in Germany, April 2015 to February 2016.

Invasive infections with Mycobacterium chimaera were reported in patients with previous open chest surgery and exposure to contaminated heater-cooler units (HCUs). We present results of the surveillance of clinical cases and of contaminated HCUs as well as environmental investigations in Germany up until February 2016. Clinical infections occurred in five male German cases over 50 years of age (range 53-80). Cases had been exposed to HCUs from one single manufacturer during open chest surgery up to five years prior to onset of symptoms. During environmental investigations, M. chimaera was detected in samples from used HCUs from three different countries and samples from new HCUs as well as in the environment at the manufacturing site of one manufacturer in Germany. Our investigation suggests that at least some of the M. chimaera infections may have been caused by contamination of HCUs at manufacturing site. We recommend that until sustainable measures for safe use of HCUs in operation theatres are implemented, users continue to adhere to instructions for use of HCUs and Field Safety Notices issued by the manufacturer, implement local monitoring for bacterial contamination and continuously check the websites of national and European authorities for current recommendations for the safe operation of HCUs.

Epidemiological and Molecular Investigation of the Heater-Cooler Unit (HCU)-Related Outbreak of Invasive Mycobacterium chimaera Infection Occurred in Italy.

BACKGROUND: From 2013 onwards, a large outbreak of Mycobacterium chimaera (MC) invasive infection, which was correlated with the use of contaminated heater-cooler units (HCUs) during open chest surgery, was reported from all over the world. Here, we report the results of the epidemiological and molecular investigations conducted in Italy after the alarm raised about this epidemic event. METHODS: MC strains isolated from patients or from HCU devices were characterized by genomic sequencing and molecular epidemiological analysis. RESULTS: Through retrospective epidemiological analysis conducted between January 2010 and December 2022, 40 possible cases of patients infected with MC were identified. Thirty-six strains isolated from these patients were analysed by whole genome sequencing (WGS) and were found to belong to the genotypes 1.1 or 1.8, which are the genotypes correlated with the outbreak. Most of the cases presented with prosthetic valve endocarditis, vascular graft infection or disseminated infection. Among the cases found, there were 21 deaths. The same analysis was carried out on HCU devices. A total of 251 HCUs were found to be contaminated by MC; genotypes 1.1 or 1.8 were identified in 28 of those HCUs. CONCLUSIONS: To ensure patients' safety and adequate follow-up, clinicians and general practitioners were made aware of the results and public health measures, and recommendations were issued to prevent further cases in the healthcare settings. The Italian Society of Cardiac Surgery performed a national survey to assess the incidence of HCU-related MC prosthetic infections in cardiac surgery. No cases were reported after HCU replacement or structural modification and disinfection and possibly safe allocation outside surgical rooms.

A Case of Cavitary Mycobacterium chimaera.

Mycobacterium chimaera is a nontuberculous mycobacterium typically associated with heater-cooler units used in cardiac bypass procedures and is usually of low virulence. Here we present a patient with advanced Mycobacterium chimaera infection without typical risk factors.

Investigating the Origin of Mycobacterium chimaera Contamination in Heater-Cooler Units: Integrated Analysis with Fourier Transform Infrared Spectroscopy and Whole-Genome Sequencing.

Mycobacterium chimaera is ubiquitously spread in the environment, including factory and hospital water systems. Invasive cases of M. chimaera infection have been associated with aerosols produced by the use of heater-cooler units (HCU) during cardiac surgery. The aim of this study was to evaluate for the first time the performance of IR-Biotyper system on a large number of M. chimaera isolates collected from longitudinal environmental HCUs samples and water sources from hospitals located in three Italian provinces. In addition, IR-Biotyper results were compared with whole-genome sequencing (WGS) analysis, the reference method for molecular epidemiology, to investigate the origin of M. chimaera contamination of HCUs. From November 2018 to May 2021, 417 water samples from 52 HCUs (Stockert 3T, n = 41 and HCU40, n = 11) and 23 hospital taps (used to fill the HCU tanks) were concentrated, decontaminated, and cultured for M. chimaera. Positive cultures (n = 53) were purified by agar plate subcultures and analyzed by IR-Biotyper platform and Ion Torrent sequencing system. IR-Biotyper spectra results were analyzed using a statistical approach of dimensionality reduction by linear discriminant analysis (LDA), generating three separate clusters of M. chimaera, ascribable to each hospital. Furthermore, the only M. chimaera-positive sample from tap water clustered with the isolates from the HCUs of the same hospital, confirming that the plumbing system could represent the source of HCU contamination and, potentially, of patient infection. According to the genome-based phylogenies and following the classification proposed by van Ingen and collaborators in 2017, three distinct M. chimaera groups appear to have contaminated the HCU water systems: subgroups 1.1, 2.1, and branch 2. Most of the strains isolated from HCUs at the same hospital share a highly similar genetic profile. The nonrandom distribution obtained with WGS and IR-Biotyper leads to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, in addition with the current hypothesis that contamination occurs at the HCU production site. This opens the possibility that other medical equipment, such as endoscope reprocessing device or hemodialysis systems, could be contaminated by M. chimaera. IMPORTANCE Our manuscript focuses on interventions to reduce waterborne disease transmission, improve sanitation, and control infection. Sanitary water can be contaminated by nontuberculous Mycobacteria, including M. chimaera, a causative agent of invasive infections in immunocompromised patients. We found highly similar genetic and phenotypic profiles of M. chimaera isolated from heater-cooler units (HCU) used during surgery to thermo-regulate patients' body temperature, and from the same hospital tap water. These results lead to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, adding to the current hypothesis that contamination occurs at the HCU production site. In addition, this opens the possibility that other medical equipment using sanitized water, such as endoscope reprocessing devices or hemodialysis systems, could be contaminated by nontuberculous Mycobacteria, suggesting the need for environmental surveillance and associated control measures.

Mycobacterium chimaera Genomics With Regard to Epidemiological and Clinical Investigations Conducted for an Open Chest Postsurgical Mycobacterium chimaera Infection Outbreak.

BACKGROUND: Postsurgical infections due to Mycobacterium chimaera appeared as a novel nosocomial threat in 2015, with a worldwide outbreak due to contaminated heater-cooler units used in open chest surgery. We report the results of investigations conducted in France including whole-genome sequencing comparison of patient and heater-cooler unit isolates. METHODS: We sought M. chimaera infection cases from 2010 onwards through national epidemiological investigations in health care facilities performing cardiopulmonary bypass, together with a survey on good practices and systematic heater-cooler unit microbial analyses. Clinical and heater-cooler unit isolates were subjected to whole-genome sequencing analyzed with regard to the reference outbreak strain Zuerich-1. RESULTS: Only 2 clinical cases were shown to be related to the outbreak, although 23% (41/175) of heater-cooler units were declared positive for M. avium complex. Specific measures to prevent infection were applied in 89% (50/56) of health care facilities, although only 14% (8/56) of them followed the manufacturer maintenance recommendations. Whole-genome sequencing comparison showed that the clinical isolates and 72% (26/36) of heater-cooler unit isolates belonged to the epidemic cluster. Within clinical isolates, 5-9 nonsynonymous single nucleotide polymorphisms were observed, among which an in vivo mutation in a putative efflux pump gene was observed in a clinical isolate obtained for 1 patient on antimicrobial treatment. CONCLUSIONS: Cases of postsurgical M. chimaera infections have been declared to be rare in France, although heater-cooler units were contaminated, as in other countries. Genomic analyses confirmed the connection to the outbreak and identified specific single nucleotide polymorphisms, including 1 suggesting fitness evolution in vivo.

Mycobacterium chimaera in heater-cooler units used during cardiac surgery - growth and decontamination.

BACKGROUND: Previous studies have identified patients infected with Mycobacterium chimaera (M. chimaera) subsequent to cardiac surgery. Water tanks in heater-cooler units (HCUs) used cardiac heart surgery was traced as source. The aim was to investigate occurrence of M. chimaera and other microorganisms in HCUs and evaluate the silver-ion cleaning routine. METHOD: Five HCUs were disinfected with silver-ions and examined for mycobacteria directly (15 min) after the disinfection procedures and later on three occasions (3, 6, 10 weeks). One HCU was selected for additional investigation of the presence of other microorganisms. In addition, tap water from five sinks in the surgical department was examined for the presence of mycobacteria and other microorganisms. RESULTS: M. chimaera grew in all the HCU water tanks and in 35 of the 40 HCU samples. Three of the samples also contained Mycobacterium gordonae. When the selected HCU tanks were analysed directly after the disinfection procedure bacteria and fungi were found but no non-fermenting Gram-negative rods. These HCU samples contained a doubled to 3 fold amount of bacteria compared to initial tap water samples. No mycobacteria were found in any sample from the five water taps. CONCLUSION: The silver-ion cleaning routine was insufficient and M. chimaera was found in all HCUs. However, no mycobacteria were found in any sample from the five water taps suggesting another source of colonization. It is probable that residual water and biofilm are of importance. Our results emphasize the need for improved disinfection procedures and improved construction of the HCUs.

Mycobacterium Chimaera Mimicking Sarcoidosis.

Mycobacterium chimaera (M. chimaera) is a slow-growing nontuberculous mycobacteria usually associated with pulmonary infection in immunocompromised patients. Attributed to a specific brand of contaminated heater-cooler units used during cardiac surgery, M. chimaera has become a global public health concern due to disseminated infection affecting immunocompetent hosts. Given its nonspecific presenting symptoms and indolent course of infection, M. chimaera can mimic and be misdiagnosed as sarcoidosis. Increased awareness among the medical community and at-risk population should be maintained to facilitate more rapid diagnosis and prevent inappropriate treatment of this potentially devastating condition.

OR Air Quality: Is It Time to Consider Adjunctive Air Cleaning Technology?: 1.3 www.aornjournal.org/content/cme.

Patients undergoing surgery may be at risk for infection from airborne particles such as dust, skin scales, respiratory aerosols, and hair fibers emanating from multiple sources in the OR, including personnel, heater-cooler devices, and surgical smoke. This risk is increased in surgical patients undergoing procedures involving implanted devices. Surgical personnel also are at risk from exposure to surgical smoke, which can contain viable viral particles including human papillomavirus infection. Air quality in the OR is improved by engineering controls (eg, maintaining positive pressure). During the past decade, innovations in the field of adjunctive technology designed to improve OR air quality include using ultraviolet disinfection and mobile ultraviolet disinfection plus high-efficiency particulate air filtration. Some of these technologies additionally provide continuous monitoring of circulating air particle counts. Additional research regarding the benefits of adjunctive air-cleaning technology in the OR is warranted.

Persistent contamination of heater-cooler units for extracorporeal circulation cured by chlorhexidine-alcohol in water tanks.

Recently, surgical site infections due to non-tuberculous mycobacteria (NTM) have been linked to heater-cooler unit contamination. The European Centre for Disease Prevention and Control and manufacturers now recommend the use of hydrogen peroxide in filtered water to fill heater-cooler unit tanks. After implementation of these measures in our hospital, heater-cooler units became heavily contaminated by opportunistic waterborne pathogens such as Pseudomonas aeruginosa and Stenotrophomonas maltophilia. No NTM were detected but fast-growing resistant bacteria could impair their detection. The efficiency of hydrogen peroxide and chlorhexidine-alcohol was compared in situ. Chlorhexidine-alcohol treatment stopped waterborne pathogen contamination and NTM were not cultured whereas their detection efficiency was probably improved.

Fast update of undetected Mycobacterium chimaera infections to reveal unsuspected cases.

Mycobacterium chimaera is involved in a worldwide alert due to contaminated heater-cooler units. A real-time polymerase chain reaction (RT-PCR)-based procedure was implemented to survey undetected cases of M. chimaera infection. PCR was negative in the 59 prosthetic heart valves from patients with PCR-16SrRNA-negative infective endocarditis. PCR identified M. chimaera in one of 15 clinically significant retrospective Mycobacterium avium-Mycobacterium intracellulare complex isolates, which corresponded to a patient who had undergone heart valve replacement in a different institution. Whole-genome sequencing demonstrated that he was the first case in Spain with involvement of the strain responsible for the global outbreak. These results highlight the relevance of retrospective tracking for undetected M. chimaera infections.

Mycobacterium chimaera Infection After Aortic Valve Replacement Presenting With Aortic Dissection and Pseudoaneurysm.

We present a case of Mycobacterium chimaera infection presenting with aortic dissection and pseudoaneuysm in a 22-year-old man with a past history of aortic valve replacement. Clinicians should consider M. chimaera infection in those presenting with aortic dissection as a late complication of cardiovascular surgery.

A novel wall water system for cardiopulmonary bypass may reduce the risk of aerosolized infection.

OBJECTIVE: Oxygenators for cardiopulmonary bypass require water flow for their integral heat exchanger. Heater-cooler units are nearly universally used for this requirement. Heater-cooler units pose the risk of aerosolized infection. The Centers for Disease Control and Prevention recommended discontinuing use of Stöckert 3T heater-cooler units (LivaNova PLC, London, United Kingdom) in October 2016 because of this risk. We aimed to reduce the risk of aerosolized infection posed by heater-cooler units by eliminating those devices from our operating rooms. METHODS: The cardiac surgery division collaborated with in-house specialties to engineer a novel wall water system. The design called for service to 4 operating rooms with the actual water mixing valve in an operating room closet. Remote temperature control was mounted next to the heart-lung machine. Primary safety systems built into the water system include 5 µm filtration, pressure regulating and relief valves, flow quantifiers, limits to the hot and chilled input temperatures, and a novel bridge near the heart-lung machine that allows the perfusionist to test the system before patient use and to quickly disconnect the patient in case of system malfunction. In addition, all water line connections can be made with the tubing drained and never under pressure. RESULTS: This novel wall water system has successfully provided heat exchanger water flow on 625 patients undergoing congenital heart surgery requiring cardiopulmonary bypass during its first 9 months of use. CONCLUSIONS: Wall water systems are an option for oxygenator heat exchangers that allow for improved heat exchange performance while reducing the risk of heater-cooler unit-associated infection during cardiac surgery.