Bacterial Colonization in Humidifying Cascade Reservoirs After 24 and 48 Hours of Continuous Mechanical Ventilation

1987 ◽  
Vol 8 (5) ◽  
pp. 200-203 ◽  
Author(s):  
Theresa A. Goularte ◽  
Marie Manning ◽  
Donald E. Craven

AbstractWe evaluated levels of bacterial colonization in the humidifying cascade reservoirs of 466 mechanical ventilators; 326 reservoirs were cultured after 24 hours and 140 were cultured after 48 hours of continuous mechanical ventilation. Bacterial colonization was absent in 284 (87.1%) of the humidifier reservoirs sampled at 24 hours and 125 (89.3%) of the reservoirs cultured at 48 hours. Levels of bacterial colonization in the remaining humidifiers were low (<100 organisms/mL). The median temperature recorded in the reservoir fluid of 30 different ventilators was 50°C (range 40° to 60°C). In vitro seeding of reservoir fluid at 50°C with 106 organisms/mL of four different species of nosocomial gram-negative bacilli and Staphylococcus aureus demonstrated rapid killing of all five strains over a 6-hour incubation period, and no significant bacterial aerosols were detected. Rates and levels of bacteria in heated humidifier reservoirs are low and nosocomial pathogens survive poorly at the median reservoir temperature of 50°C. We conclude that the heated humidifier reservoir on a mechanical ventilator is an unlikely source of colonization or bacterial aerosols, and therefore it can be changed every 48 hours with the ventilator tubing.

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yina Faizully Quintero-Gamboa ◽  
Carlos Andrés Aguirre-Rodríguez ◽  
Aradeisy Ibarra-Picón ◽  
Edwin Rua-Ramírez ◽  
Edwin Gilberto Medina-Bejarano

In times of crisis in public health where the resources available in the hospital network are scarce and these must be used to the fullest, innovative ideas arise, which allow multiplying the use of existing resources, as artificial mechanical ventilators can be. These can be used in more than one patient, by attaching a device to distribute the mixture of air and oxygen from the ventilator being used simultaneously (multiple mechanical ventilation). This idea, although innovative, has generated controversy among the medical community, as many fear for the safety of their patients, because attaching such devices to the ventilator loses control over the mechanical ventilation variables of each patient and can only maintain general vigilance over the ventilator. These misgivings about the device have led several researchers to take on the task of verifying the reliability of this flow splitter connector. It is for this reason that this article presents a thorough review of the studies carried out on the subject and additionally shows an analysis of comparative costs between the acquisition of a mechanical ventilator and the flow division system.


2020 ◽  
Author(s):  
Uri Adrian Prync Flato ◽  
Patricia C. dos Santos ◽  
Fábio Manhoso ◽  
Fernanda Mesquita Serva ◽  
Jeferson Dias ◽  
...  

Abstract Background: The current need for pulmonary mechanical ventilation related to COVID-19 exceeds the ability of health systems worldwide to acquire and produce mechanical ventilators. The major cause of mortality in patients with this disease is hypoxemia secondary to an inflammatory storm in the lungs associated with thrombotic events. A partnership was established between the university and the private engineering and industrial automation sector to concept and design novel a low-cost emergency mechanical ventilator that could be rapidly available for use in emergency, transport or low-resource health care system, and attend the urgent demand of artificial respiratory system that is need worldwide. It was evaluated the viability of oxygenation and pulmonary ventilation with an emergency mechanical ventilation device called 10D-EMV in animal experiments. A two-stage sequential adaptive study was conducted in 10 sheep, divided into group I (PEEP valve close to the device) and group II (PEEP valve distal to the device). Each animal underwent mechanical ventilation for a total of 120 minutes. Results: The mean oxygenation in group I and group II were 368 mmHg and 366 mmHg, respectively, while the mean partial pressure of carbon dioxide was 58 mmHg and 48 mmHg. Conclusion: This study demonstrates the viability of the 10D device as a novel proposed emergency mechanical ventilator, in order to attend the pandemics demand. Further clinical studies in humans are needed to assess its safety and efficacy.


Author(s):  
Bilal A. Mateen ◽  
Harrison Wilde ◽  
John M. Dennis ◽  
Andrew Duncan ◽  
Nicholas J. Thomas ◽  
...  

AbstractBackgroundNon-pharmacological interventions were introduced based on modelling studies which suggested that the English National Health Service (NHS) would be overwhelmed by the COVID-19 pandemic. In this study, we describe the pattern of bed occupancy across England during the first wave of the pandemic, January 31st to June 5th 2020.MethodsBed availability and occupancy data was extracted from daily reports submitted by all English secondary care providers, between 27-Mar and 5-June. Two thresholds for ‘safe occupancy’ were utilized (85% as per Royal College of Emergency Medicine and 92% as per NHS Improvement).FindingsAt peak availability, there were 2711 additional beds compatible with mechanical ventilation across England, reflecting a 53% increase in capacity, and occupancy never exceeded 62%. A consequence of the repurposing of beds meant that at the trough, there were 8·7% (8,508) fewer general and acute (G&A) beds across England, but occupancy never exceeded 72%. The closest to (surge) capacity that any trust in England reached was 99·8% for general and acute beds. For beds compatible with mechanical ventilation there were 326 trust-days (3·7%) spent above 85% of surge capacity, and 154 trust-days (1·8%) spent above 92%. 23 trusts spent a cumulative 81 days at 100% saturation of their surge ventilator bed capacity (median number of days per trust = 1 [range: 1 to 17]). However, only 3 STPs (aggregates of geographically co-located trusts) reached 100% saturation of their mechanical ventilation beds.InterpretationThroughout the first wave of the pandemic, an adequate supply of all bed-types existed at a national level. Due to an unequal distribution of bed utilization, many trusts spent a significant period operating above ‘safe-occupancy’ thresholds, despite substantial capacity in geographically co-located trusts; a key operational issue to address in preparing for a potential second wave.FundingThis study received no funding.Research In ContextEvidence Before This StudyWe identified information sources describing COVID-19 related bed and mechanical ventilator demand modelling, as well as bed occupancy during the first wave of the pandemic by performing regular searches of MedRxiv, PubMed and Google, using the terms ‘COVID-19’, ‘mechanical ventilators’, ‘bed occupancy’, ‘England’, ‘UK’, ‘demand’, and ‘non-pharmacological interventions (NPIs)’, until June 20th, 2020. Two UK-specific studies were found that modelled the demand for mechanical ventilators, one of which incorporated sensitivity analysis based on the introduction of NPIs and found that their effects might prevent the healthcare system being overwhelmed. Separately, several news reports were found pertaining to a single hospital that reached ventilator capacity in England during the first wave of the pandemic, however, no single authoritative source was identified detailing impact across all hospital sites in England.Added Value of This StudyThis national study of hospital-level bed occupancy in England provides unique and timely insight into bed-specific resource utilization during the first wave of the COVID-19 pandemic, nationally, and by specific (geographically defined) health footprints. We found evidence of an unequal distribution of resource utilization across England. Although occupancy of beds compatible with mechanical ventilation never exceeded 62% at the national level, 52 (30%) hospitals across England reached 100% saturation at some point during the first wave of the pandemic. Close examination of the geospatial data revealed that in the vast majority of circumstances there was relief capacity in geographically co-located hospitals. Over the first wave it was theoretically possible to markedly reduce (by 95.1%) the number of hospitals at 100% saturation of their mechanical ventilator bed capacity by redistributing patients to nearby hospitals.Implications Of All The Available EvidenceNow-casting using routinely collected administrative data presents a robust approach to rapidly evaluate the effectiveness of national policies introduced to prevent a healthcare system being overwhelmed in the context of a pandemic illness. Early investment in operational field hospital and an independent sector network may yield more overtly positive results in the winter, when G&A occupancy-levels regularly exceed 92% in England, however, during the first wave of the pandemic they were under-utilized. Moreover, in the context of the non-pharmacological interventions utilized during the first wave of COVID-19, demand for beds and mechanical ventilators was much lower than initially predicted, but despite this many trust spent a significant period of time operating above ‘safe-occupancy’ thresholds. This finding demonstrates that it is vital that future demand (prediction) models reflect the nuances of local variation within a healthcare system. Failure to incorporate such geographical variation can misrepresent the likelihood of surpassing availability thresholds by averaging out over regions with relatively lower demand, and presents a key operational issue for policymakers to address in preparing for a potential second wave.


2022 ◽  
Author(s):  
Tian-Ran. Li ◽  
Lan-Ping. Shi ◽  
Yong-Gang. Jia ◽  
Ricky Wing Tong. Lau ◽  
Xia-Zhen. Pan

Abstract Background:Although the circuit condensate, an ideal bacterial reservoir, may flow into the humidifier reservoir (HR), no study has investigated if HR-colonized bacteria colonize other circuit locations with airflow. Therefore, the objective of this study was to explore if bacterial growth in the HR leads to bacterial colonization in the ventilator circuit. Methods: A randomized controlled experiment was performed in a public tertiary hospital in Guangdong Province, China. In vitro mechanical ventilation models (n = 60), divided into sterile water samples (n = 30) and broth samples (n = 30), were established. Sterile water was used for humidification in the ventilation models. The sterile water group contained either Acinetobacter baumannii (n = 15) or Pseudomonas aeruginosa (n = 15) in humidifier water. The broth group was similar to the sterile water group, but brain heart infusion broth was added to the HR. After 24, 72, and 168 h of continuous ventilation, bacteria in the humidifier water and at different circuit locations were sampled and cultured, and the results were analyzed by the Chi-square test. The difference in bacterial concentration at the HR outlet was analyzed by the F test, and P < 0.05 was considered statistically significant.Results:Bacterial culture results of the sterile water samples were negative. Bacteria in the humidifier water continued to proliferate in the broth group, and the bacterial concentration at different times was not significantly different (P > 0.05). With prolonged ventilation, the bacterial concentration at the HR outlet increased (P < 0.05). During continuous ventilation, no bacterial growth occurred at 10 cm from the HR outlet and the Y-piece of the ventilator circuit. The bacterial concentration at the HR outlet was higher in the P. aeruginosa group than in the A. baumannii group (P < 0.05).Conclusions:Sterile water in the HR was not conducive to bacterial growth. Although bacteria grew in the HR and could reach the HR outlet, colonization of other circuit locations was unlikely.


Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 459 ◽  
Author(s):  
Ching-Yi Liu ◽  
Hsin-Kuo Ko ◽  
James Fink ◽  
Gwo-Hwa Wan ◽  
Chung-Chi Huang ◽  
...  

Although aerosol delivery through mechanical ventilators has been used to administer various medications, little is known of administration with colistin. This in vitro evaluation aimed to evaluate size distribution of colistin delivery by different types of nebulizers and concentrations during mechanical ventilation. Colistin methanesulfonate (colistin) for injection was dissolved in 6 mL of distilled water to produce a low concentration (L; 156 mg) and a high concentration (H; 312 mg). A dose volume of 6 mL was placed in a vibrating mesh nebulizer (VMN) and a jet nebulizer (JN). The inhaled mass (mean ± SD) of the VMN-L (53.80 ± 14.79 mg) was greater than both the JN-L (19.82 ± 3.34 mg, P = 0.001) and JN-H (31.72 ± 4.48 mg, P = 0.017). The nebulization time of the VMN-L (42.35 ± 2.30 min) was two times longer than the JN-L (21.12 ± 0.8 min) or JN-H (21.65 ± 0.42 min; P < 0.001). The mass median aerodynamic distal to the endotracheal tube was within a similar range at 2.03 to 2.26 μm (P = 0.434), independent of neb or formulation concentration. In conclusion, the VMN-L yields greater inhaled mass than the JN with either concentration. Therefore, a standard nominal dose of colistin results in a higher delivered dose during mechanical ventilation with a VMN compared with a JN and may be considered the preferred device. If JN must be used, multiple doses of low concentration colistin may compensate for poor delivery performance.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Jayesh Dhanani ◽  
George Pang ◽  
Jason Pincus ◽  
Benjamin Ahern ◽  
Wendy Goodwin ◽  
...  

Abstract Objective The advent of new technologies has made it possible to explore alternative ventilator manufacturing to meet the worldwide shortfall for mechanical ventilators especially in pandemics. We describe a method using rapid prototyping technologies to create an electro-mechanical ventilator in a cost effective, timely manner and provide results of testing using an in vitro–in vivo testing model. Results Rapid prototyping technologies (3D printing and 2D cutting) were used to create a modular ventilator. The artificial manual breathing unit (AMBU) bag connected to wall oxygen source using a flow meter was used as air reservoir. Controlled variables include respiratory rate, tidal volume and inspiratory: expiratory (I:E) ratio. In vitro testing and In vivo testing in the pig model demonstrated comparable mechanical efficiency of the test ventilator to that of standard ventilator but showed the material limits of 3D printed gears. Improved gear design resulted in better ventilator durability whilst reducing manufacturing time (< 2-h). The entire cost of manufacture of ventilator was estimated at 300 Australian dollars. A cost-effective novel rapid prototyped ventilator for use in patients with respiratory failure was developed in < 2-h and was effective in anesthetized, healthy pig model.


Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1797
Author(s):  
Manuel Toledano ◽  
Marta Vallecillo-Rivas ◽  
María T. Osorio ◽  
Esther Muñoz-Soto ◽  
Manuel Toledano-Osorio ◽  
...  

Barrier membranes are employed in guided bone regeneration (GBR) to facilitate bone in-growth. A bioactive and biomimetic Zn-doped membrane with the ability to participate in bone healing and regeneration is necessary. The aim of the present study is to state the effect of doping the membranes for GBR with zinc compounds in the improvement of bone regeneration. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI, Embase, Scopus and Web of Science. A narrative exploratory review was undertaken, focusing on the antibacterial effects, physicochemical and biological properties of Zn-loaded membranes. Bioactivity, bone formation and cytotoxicity were analyzed. Microstructure and mechanical properties of these membranes were also determined. Zn-doped membranes have inhibited in vivo and in vitro bacterial colonization. Zn-alloy and Zn-doped membranes attained good biocompatibility and were found to be non-toxic to cells. The Zn-doped matrices showed feasible mechanical properties, such as flexibility, strength, complex modulus and tan delta. Zn incorporation in polymeric membranes provided the highest regenerative efficiency for bone healing in experimental animals, potentiating osteogenesis, angiogenesis, biological activity and a balanced remodeling. Zn-loaded membranes doped with SiO2 nanoparticles have performed as bioactive modulators provoking an M2 macrophage increase and are a potential biomaterial for promoting bone repair. Zn-doped membranes have promoted pro-healing phenotypes.


2011 ◽  
Vol 82 (4) ◽  
pp. 613-618 ◽  
Author(s):  
Theofilos Koutouzis ◽  
Shannon Wallet ◽  
Nadia Calderon ◽  
Tord Lundgren

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 51
Author(s):  
Jozef Živčák ◽  
Michal Kelemen ◽  
Ivan Virgala ◽  
Peter Marcinko ◽  
Peter Tuleja ◽  
...  

COVID-19 was first identified in December 2019 in Wuhan, China. It mainly affects the respiratory system and can lead to the death of the patient. The motivation for this study was the current pandemic situation and general deficiency of emergency mechanical ventilators. The paper presents the development of a mechanical ventilator and its control algorithm. The main feature of the developed mechanical ventilator is AmbuBag compressed by a pneumatic actuator. The control algorithm is based on an adaptive neuro-fuzzy inference system (ANFIS), which integrates both neural networks and fuzzy logic principles. Mechanical design and hardware design are presented in the paper. Subsequently, there is a description of the process of data collecting and training of the fuzzy controller. The paper also presents a simulation model for verification of the designed control approach. The experimental results provide the verification of the designed control system. The novelty of the paper is, on the one hand, an implementation of the ANFIS controller for AmbuBag pressure control, with a description of training process. On other hand, the paper presents a novel design of a mechanical ventilator, with a detailed description of the hardware and control system. The last contribution of the paper lies in the mathematical and experimental description of AmbuBag for ventilation purposes.


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