Tag: mechanical ventilation

Categories : Hospitals Respiratory DiseasesTags :

Biofilms in Ventilation Tubes Make Pathogens Even More Resistant to Antibiotics

On By ModernMedia

Scientists at The University of Warwick have made a breakthrough which could help find new ways to prevent ventilator-associated pneumonia, which can affect up to 40% of hospital patients on mechanical ventilators.

Ventilator-associated pneumonia (VAP) is a common infection in ventilated patients, particularly for those with existing respiratory conditions. VAP is transmitted by pathogens, often antibiotic resistant, that form stubborn biofilms on the inside of endotracheal tubes. Up to 40% of ventilated patients in intensive care wards will develop VAP, with 10% of those patients dying as a result.

In a study recently published in Microbiology, researchers recreated hospital conditions to improve understanding of the infection. They used the same type of endotracheal tubes and created a special mucus to simulate the conditions inside a human body. Bacteria and fungi formed a biofilm on these tubes.

Dr Dean Walsh, Research Fellow, University of Warwick, said: “Our study found that the biofilms in our model were different and more complex than those usually grown in standard lab conditions, making them more realistic.

“The biofilms formed in this new model were very tough to get rid of, even with strong antibiotics, much like what happens in real patients.

“Significantly, when we combined antibiotics with enzymes that break down the biofilm’s protective slime layer, the biofilms were more successfully removed than with antibiotics alone. With the enzymes, we could halve the concentration of antibiotics needed to kill the biofilms. So, that suggests we can use our model to identify new VAP treatments that attack the slime layer.”

Dr Freya Harrison, School of Life Sciences, University of Warwick, added: “VAP is a killer, and there are currently no cost-effective ways of making the tubes harder for microbes to colonise. Our new model can help scientists develop better therapies and design special tubes that prevent biofilms, which could improve the health of patients on ventilators.”

This project was part of an international research program in antimicrobial resistance that brings together colleagues at the University of Warwick with those at Monash University in Melbourne and is supported by the Monash-Warwick Alliance.

Professor Ana Traven, co-Director of the Monash-Warwick Alliance programme in emerging superbug threats, and co-author of the study, added: “It is exciting that we could join forces with our colleagues at Warwick for this important study.  Many promising new anti-infectives fail because experiments done in the laboratory do not recapitulate very well the more complex infections that occur in patients. As such, the development of laboratory models that mimic disease, such as was done in this study, is important for accelerating the discovery of credible antimicrobial therapies that have a higher chance of clinical success.”

Source: Microbiology Society

Categories : COVIDTags :

Prone Positioning in COVID Reduces the Need for Endotracheal Intubation

On By ModernMedia
Photo by Samuel Ramos on Unsplash

COVID patients hospitalised for acute respiratory distress syndrome (ARDS) are less likely to need endotracheal intubation with prone positioning, but evidence is inconclusive for other outcomes such as mortality, suggests an in-depth analysis of the latest evidence published by The BMJ.

Since the 1970s, prone positioning has been standard care for patients with severe ARDS as it encourages a larger part of the lung to expand, enabling bigger breaths. 

Usually, it is done for critically ill patients who are sedated and intubated. But in February 2020, reports emerged of possible benefits from prone positioning of awake COVID and it was widely adopted. 

Since then, several studies have examined its effectiveness in awake COVID patients , but results have been conflicting.

To try and resolve this uncertainty, researchers trawled databases for randomised trials comparing awake prone positioning to usual care for adult COVID patients with hypoxaemic respiratory failure.

They found 17 suitable trials, 12 with no bias risk, involving 2931 non-intubated patients who were able to breathe unassisted and who spent an average of 2.8 hours per day lying prone.

The primary outcome was endotracheal intubation, and secondary outcomes included mortality, ventilator-free days, intensive care unit (ICU) and hospital length of stay, change in oxygenation and respiratory rate, and adverse events.

High certainty evidence from a pooled analysis of 14 trials showed that awake prone positioning reduced the risk of endotracheal intubation compared with usual care (24.2% with awake prone positioning vs 29.8% with usual care). On average, awake prone positioning resulted in 55 fewer intubations per 1000 patients.

However, high certainty evidence from a pooled analysis of 13 trials evaluating mortality did not show a significant difference in mortality between the two groups (15.6% with awake prone positioning vs 17.2% with usual care), but the study may have lacked statistical power to detect a difference.

Awake prone positioning did not significantly affect other secondary outcomes either, including, ventilator-free days, ICU or hospital length of stay, based on low and moderate certainty evidence.

Limitations included lack of individual patient data, differences between the targeted and achieved duration of awake prone positioning, and variation in the definition and reporting of certain outcomes across studies.

But further sensitivity analysis supported these results, suggesting a high probability of benefit for the endotracheal intubation outcome and a low probability of benefit for mortality.

As such, the researchers conclude: “Awake prone positioning compared with usual care reduces the risk of endotracheal intubation in adults with hypoxemic respiratory failure due to covid-19 but probably has little to no effect on mortality or other outcomes.”

In a linked editorial, researchers point out that the benefits of prone positioning in COVID patients may be confined to those with more severe hypoxaemia and longer duration of prone positioning, so say it may be wise to focus efforts on these particular groups. 

Several unanswered questions remain, including the ideal daily duration of treatment, the level of hypoxaemia that should prompt prone positioning, and how best to improve patient comfort and encourage adherence, they write.

These questions may never be answered definitively in COVID patients as, fortunately, far fewer are experiencing hypoxaemic respiratory failure or critical illness, they explain.

“The pandemic should, however, renew interest and encourage further evaluation of awake prone positioning – an intervention that may benefit a wide range of patients with hypoxaemia,” they conclude.

Source: EurekAlert!

Categories : COVID NeurologyTags :

Delayed COVID Recovery could be a Protective Mechanism against Hypoxia

On By ModernMedia
Photo by Andrea Piacquadio on Unsplash

COVID patients placed on ventilators can take a long time to regain consciousness. New research published the Proceedings of the National Academy of Sciences now shows that these delays may serve a purpose: protecting the brain from oxygen deprivation.

The existence of such a brain-preserving state could explain why some patients wake up days or even weeks after they stop receiving ventilation, and it suggests that physicians should take these lengthy recovery times into account when determining a patient’s prognosis.

In their study, investigators connect the pattern seen among those who have survived severe COVID with similar delays known to occur in a small fraction of cardiac arrest patients.

“The delayed recoveries in COVID patients are very much like the rare cases we’ve documented in previous research. In this new paper, we describe a mechanism to explain what we’re seeing in both types of patients,” said study co-senior author Dr Nicholas D. Schiff, a neurology professor at Weill Cornell Medicine.

He suggests that this mechanism is the brain protecting itself, pointing to animals, most notably painted turtles, that can tolerate extended periods without oxygen.

More than a decade ago, Dr Schiff and his colleagues first observed these delays among comatose cardiac arrest patients who received cooling therapy to reduce brain damage caused by a loss of blood flow. In one such case, a 71-year-old patient took 37 days to awaken, before ultimately making a near-complete recovery.

During the pandemic, Dr Schiff performed neurology consultations for COVID patients, and he soon began seeing similar, delayed awakenings occurring when patients were taken off ventilators and stopped receiving movement-limiting sedatives.

In a separate analysis of a large cohort of COVID patients from Weill Cornell Medicine and two other major U.S. medical centres, Dr Schiff and his colleagues, including co-author of the current paper, Dr Emery N. Brown, professor of anaesthesia at Harvard Medical School, found that a quarter of patients who survived ventilation took 10 days or longer to recover consciousness. The more oxygen deprivation they suffered while on the ventilator, the longer that delay.

In the prior study of cardiac patients, the researchers recorded a distinctive pattern in brain activity, one also seen in patients under deep anaesthesia. (Recordings from COVID patients are extremely limited.) Dr Schiff read that a similar pattern had been seen in the brains of painted turtles, which can withstand up to five months without oxygen under ice in the winter. To do so, they activate the same inhibitory system within the brain targeted by anaesthetics given to human cardiac and COVID patients but in novel ways developed by evolutionary specialisations.

Drs Schiff and Brown propose that, by chance, the same protective response emerges in the patients.

“It is our theory that oxygen deprivation as well as practices in the ICU, including commonly used anaesthetics, expose elements of strategies that animals use to survive in extreme conditions,” Dr Schiff said.

“These observations may offer new insights into the mechanisms of how certain anaesthetics produce unconsciousness and new approaches for ICU sedation and for fostering recovery from disorders of consciousness,” Dr Brown added.

When patients fail to regain consciousness for an extended time, physicians may recommend withdrawing life-supporting care. This threshold is typically set at 14 days or less for cardiac patients, while no such guidelines exist for COVID.

In light of this new research, however, so long as they lack brain injuries, physicians should avoid making negative projections about these patients’ potential to recover, note the researchers.

Source: Weill Cornell Medicine

Categories : Respiratory DiseasesTags :

Modern Ventilators Shown to Overstretch Lung Tissue

On By ModernMedia
Source: Pixabay CC0

In pulmonary medicine, it has long been debated as to whether ventilator overstretches lung tissue, and now new research published in the American Journal of Respiratory and Critical Care Medicine has proven that they do in fact cause overstretching.

The University of California Riverside researchers showed that there were major differences between natural breathing versus the forced breathing from ventilators. These results are critical, particularly in context of the COVID pandemic and the rush to build ventilators.

“Using novel techniques, we observed that ventilators can overextend certain regions of the lungs,” said Mona Eskandari, assistant professor of mechanical engineering, who led the research. These results may explain why lung health declines for patients the longer they spend on the machines, especially in the case of disease.

Eskandari’s bMECH lab pioneered a technique to study lungs as they are made to breathe. On a custom-built ventilator designed in their lab, the researchers imitated both natural and artificial breathing. Then, they observed isolated lungs involved in both types of breathing using multiple cameras collecting fast, high-resolution images, a method called digital image correlation.

“Our setup allows us to imitate both physiological and artificial breathing on the same lung with the switch of a button,” Eskandari said. “The unique combination of our ventilator with digital image correlation gives us unprecedented insights into the way specific regions of the lungs work in concert with the whole.”

Using their innovative method to interface these two systems, UCR researchers collected evidence demonstrating that natural breathing stretches certain parts of the lung as little as 25% while those same regions stretch to as much as 60% when on a ventilator.

Scholars traditionally model the lungs like balloons, or what they refer to as thin-walled pressure vessels, where pushing air in and pulling air out are understood to be mechanically equivalent.

To explain what they observed in this study, the researchers propose moving away from thin-walled pressure vessel models and instead towards thick-walled models. Unlike thin-walled pressure vessels theory, a thick-walled model accounts for the differing levels of stress in airways resulting from ventilators pushing air in versus natural breathing, which pulls air in. This helps to explain how airways are more engaged and air is more evenly distributed in the lung during physiological breathing.

Iron lungs, the gigantic ventilators used during the late 1940s polio outbreak, acted more like a human chest cavity, expanding the lung as it naturally would. This creates a vacuum effect that pulls air into the lungs. Though this action is gentler for the lungs, these bulky systems prevented easy access to monitoring other organs in hospital care.

By contrast, modern ventilators are more portable and easier for caretakers to work with. However, they push air into the lungs that is not evenly distributed, overstretching some parts and causing a decline in lung health over time.

While it is unlikely that hospitals will return to the iron lung models, it is possible that modern machines can be altered to reduce injury.

“Now that we know about excessive strain when air is delivered to the lungs, the question for us becomes about how we can improve ventilation strategies by emulating natural breathing,” Eskandari said.

Source: University of California – Riverside

Categories : PaediatricsTags :

Invasive Mechanical Ventilation in PICU has Lasting Neurocognitive Impacts

On By ModernMedia
Photo by Margaret Weir on Unsplash

Children in paediatric ICUs (PICUs) that undergo invasive mechanical ventilation for acute respiratory failure are left with lasting neurocognitive effects, according to a study published in JAMA.

Little is known about whether children undergoing invasive mechanical ventilation worse long-term neurocognitive function than children who do not undergo such procedures. There are concerns about neurotoxic effects of critical illness and its treatment on the developing brain. Therefore, infants and young children may be uniquely susceptible to adverse neurocognitive outcomes after invasive mechanical ventilation.

Researchers conducted a four-year sibling-matched cohort study conducted at 31 PICUs and associated neuropsychology testing centres. Children who survived PICU hospitalisation for respiratory failure and were discharged without severe cognitive dysfunction were found to have significantly lower subsequent IQ scores than their matched siblings.

“While the difference in IQ scores between patients and unexposed siblings was small, the data provide strong evidence of the existence and epidemiology of paediatric post-intensive care syndrome (PICS-p) after a single typical episode of acute respiratory failure necessitating invasive ventilation among generally healthy children,” said Martha A.Q. Curley, PhD, RN, FAAN, Professor of Nursing at the University of Pennsylvania School of Nursing (Penn Nursing) and the study’s lead researcher.

The study reaffirms the importance of assessing long-term outcomes as part of any trial evaluating acute interventions in pediatric critical care. It also underscores the importance of further study to understand which children may be at highest risk, what modifiable factors could cause it, and how it can be prevented.

Source: University of Pennsylvania

Categories : COVID HospitalsTags :

Bleeding from Full-dose Anticoagulants in COVID ICU Patients

On By ModernMedia
Photo by Mufid Majnun on Unsplash

COVID patients in intensive care units (ICU) receiving full-dose anticoagulants are significantly more likely to experience heavy bleeding than patients prescribed a smaller yet equally effective dose, according to a recent study.

The research, which compared the safety and effectiveness of blood clot treatment strategies for more than 150 critically ill COVID patients at two hospitals, found that almost all patients who experienced significant bleeding were on mechanically ventilation and receiving full-dose anticoagulants.

The results, published last month in Hospital Pharmacy, may inform treatment guidelines for blood clots in hospitalised COVID patients, who are at an increased risk for both blood clots and severe bleeding. Previous reports have found that 17% of hospitalised COVID patients experience blood clots, said first author Maya Chilbert, PharmD, clinical assistant professor in the UB School of Pharmacy and Pharmaceutical Sciences.

“A wide variety of practice exists when it comes to approaching blood clots in hospitalized patients with COVID, and there is little data to suggest improved outcomes using one strategy versus another,” said Chilbert. “Caution should be used in mechanically ventilated patients with COVID when selecting a regimen to treat blood clots, and the decision to use full-dose blood thinners should be based on a compelling indication rather than lab markers alone.”

The study analysed the outcome of blood clot treatments and the rate of bleeding events for more than 150 patients with COVID-19 who received either of two blood thinner regimens: a full-dose based on patient levels of D-dimer, and the other a smaller but higher-than-standard dosage.

Patients’ average age was 58, and all experienced elevated levels of D-dimer, fibrinogen, and prothrombin time.

Significant bleeding events were experienced by almost 14% of patients receiving full-dose anticoagulants, compared to only 3% of patients who received a higher-than-standard dosage. All patients who experienced bleeding events were on mechanical ventilation. No difference was reported in the regimens’ effectiveness at treating blood clots.
Further investigation is needed to determine the optimal strategy for treating blood clots and bleeding in hospitalised COVID patients, said Asst Prof Chilbert.

Source: University at Buffalo

Categories : COVID HospitalsTags :

Prone Positioning Reduces Need for Mechanical Ventilation

On By ModernMedia
Source: Martha Dominguez de Gouveia on Unsplash

A ‘meta-trial’ of 1100 hospitalised COVID patients requiring high-flow nasal cannula oxygen therapy suggests that prone positioning soon after admission can significantly reduce the need for mechanical ventilation.

While acute respiratory distress syndrome patients have been placed prone for years by critical care specialists, this study provides clinical evidence needed to support the use of prone positioning for patients with COVID requiring high-flow nasal cannula oxygen therapy.

The findings, published today in the Lancet Respiratory Medicine, were conducted on severely ill COVID patients between April 2020 and January 2021.

“Breathing in the prone position helps the lungs work more efficiently,” explained the study’s lead author Dr. Jie Li, associate professor and respiratory therapist at Rush University Medical Center. “When people with severe oxygenation issues are laying on their stomachs, it results in better matching of the blood flow and ventilation in the lungs which improves blood oxygen levels.”

Prof Li noted that several interventions are available to improve oxygenation in critically ill patients, but that there was little outcomes-focused clinical evidence to show that prone positioning prior to mechanical ventilation is beneficial.

Adult patients with COVID needing respiratory support from a high-flow nasal cannula agreed to participate in this clinical trial, and were randomly assigned to the supine or prone positioning groups. They were asked to stay in that position for as long as they could tolerate. Both positioning groups received high-flow oxygen therapy and standard medical management.

Patients were continually monitored to determine if mechanical ventilation was needed. This study’s data showed that patients in the prone positioning group were significantly less likely to require mechanical ventilation (33% in the awake prone positioning group vs 40% in the supine group).

Another study lead author, Stephan Ehrmann, MD, PhD, said that “for the clinical implications of our study, awake prone positioning is a safe intervention that reduces the risk of treatment failure in acute severe hypoxemic respiratory failure due to COVID-19. Our findings support the routine implementation of awake prone positioning in critically ill patients with COVID19 requiring high flow nasal cannula oxygen therapy. It appears important that clinicians improve patient comfort during prone positioning, so the patient can stay in the position for at least 8 hours a day.”

Reducing the need for mechanical ventilation cuts down on resources needed. “Ventilators can indeed save the lives of people who are no longer able to breathe on their own. That said, we now have strategies to keep patients off the ventilator, saving those devices for the sickest patients who truly need them.” Prof Li added.

Source: Medical Xpress