The study is the largest global analysis of in-flight medical events
Photo by Daniel Eledut on Unsplash
With nearly five billion people flying each year, medical emergencies in the air may be more common than most realise and they can be deadly.
A new study led by Duke Health researchers analysed more than 77, 00 in-flight medical events reported to the world’s busiest airline medical support centre. The findings show that while most incidents are minor, thousands of passengers required hospital care after landing, and hundreds died or triggered aircraft diversions.
The study, published in JAMA Network Open, was conducted in partnership with MedAire, an aviation and maritime health and safety solutions company, which also provided the data for analysis. The paper offers a rare look into how airlines respond to medical crises and why some flights are forced to divert.
“It gives us a real-world snapshot of what happens when someone gets sick in the sky and how starkly the options differ from those in a hospital,” Rotta said.
Researchers reviewed medical calls from 84 airlines across six continents, covering over 3.1 billion passenger boardings between January 2022 and December 2023.
They found that one in every 212 flights involved a medical emergency. Of those flights, about 8% of passengers were taken to the hospital after landing, and 1.7% of the total medical events were so serious they caused the plane to divert.
The most common reasons for diversion were suspected strokes, seizures, chest pain, and altered mental status. Cardiac arrest occurred in 293 cases, with survival rates far lower than on land.
Medical volunteers (often physicians) assisted in nearly one-third of emergencies. Their involvement was linked to a higher likelihood of diversion, likely because they were called upon during more serious events.
“It’s humbling to practice medicine in the air,” said Rotta, who became interested in the topic after being called upon as medical volunteer during several flights. “You’re working with limited equipment, no lab tests and no backup. Even minor issues can become major challenges.”
Rotta emphasised that airlines are generally well-prepared, especially in the US, where regulations require defibrillators and basic medical kits. However, he noted that not all airlines partner with ground-based medical support centres, an approach he believes is essential.
“Airplanes aren’t hospitals, and we shouldn’t expect them to be,” he said. “But having expert guidance from the ground can make all the difference when someone’s life is at risk.”
The findings could help shape airline policies, improve crew training and inform passengers with chronic conditions about how to prepare for travel.
A project to test how drones can be integrated into the UK’s 999 emergency response system to rapidly deliver defibrillators to patients experiencing out-of-hospital cardiac arrest (OHCA) has been launched by the University of Surrey, Air Ambulance Charity Kent Surrey Sussex, South East Coast Ambulance Service NHS Foundation Trust.
With survival rates for OHCA in the UK currently below 10%, a key challenge is the delay in delivering life-saving defibrillation. While public Automated External Defibrillators (AEDs) are widely available, getting them to a patient in time is often difficult. This 16-month project will explore using drones to rapidly deliver AEDs to the scene of an emergency.
This research is the first step towards integrating drone technology into our emergency response systems. Our ultimate goal is to develop and test the procedures needed to seamlessly introduce drone delivery of AEDs into the 999-emergency system
The initiative, which has been funded by the National Institute for Health and Care Research (NIHR), will be divided into two sections: in the first, researchers will develop and refine the drone delivery process through a series of simulations, coordinating 999 call taking, Air Traffic Control, ambulance dispatch and drone operators.
In the second part, interviews will be conducted with a diverse group of people -including OHCA survivors, family members, responders and members of the public – to understand the public’s perception of drone technology, including any barriers or concerns, and to ensure ease of use for responders.
This project is a great example of how NIHR’s RfPB programme supports life-saving innovation. Using drones to deliver defibrillators could help emergency teams reach patients faster, improve survival after cardiac arrest, and bring cutting-edge technology directly to the NHS frontline, while working with the public to ensure it’s used safely and effectively.
Professor Kevin Munro, Director of the NIHR Research for Patient Benefit (RfPB) Programme
Rapid intervention is vital in managing out-of-hospital cardiac arrests. As demand continues to grow, the opportunity to integrate this technology into future healthcare systems represents real progress in ensuring ambulance services can work with the communities they serve to strengthen the chain of survival and give patients the best chance of a positive outcome Being a partner in this research, we are eager to explore how this new initiative could strengthen our cardiac arrest care pathway.
Dr Craig Mortimer, Research Manager at South East Coast Ambulance Service NHS Foundation Trust (SECAmb)
A groundbreaking study by researchers at Rutgers Health has uncovered a way to precisely identify and target trauma sites in the body within minutes of injury. The findings, published in the journal Med (Cell Press), could revolutionise emergency care by enabling real-time diagnostics and site-specific treatments delivered within minutes of injury.
A team of scientists, led by Renata Pasqualini and Wadih Arap at the Rutgers Cancer Institute discovered something new about how the body reacts to injury. When cells are damaged, like in a major bone break, calcium levels shift, which causes certain proteins to change shape. These changed proteins, called the “traumome,” are only found in injured tissues and show up right after an injury happens. This discovery opens up a new way to treat injuries directly, without affecting healthy parts of the body.
“The moment trauma occurs, specific proteins undergo structural changes, creating a molecular footprint of injury,” said Arap. “This opens the door to delivering diagnostics or therapies directly to the site – without affecting healthy tissues.”
This discovery has relevance in emergency treatment because many medicines can affect healthy organs when they’re given too soon. With this new approach, doctors could deliver treatments like imaging agents, clotting factors or antibiotics directly to the injured area, which would help the body heal faster with fewer side effects.
“Our long-term vision is a simple injection that autonomously finds and treats injury sites,” said Pasqualini. “This could be transformative for battlefield medicine and emergency trauma care, where every second matters.”
The team used advanced testing on a pig model with major injuries to find tiny protein pieces called peptides. These peptides are like guides that can find and stick to the specific proteins altered by injury. One of these peptides stands out because it can attach to a protein that changes shape when calcium levels rise after an injury. This makes it possible to use special scans, like PET or MRI, to see exactly where the injury is in the body.
The trauma-targeting peptide worked the same way in rats, which shows that this injury “signature” is similar in all mammals, including humans.
The work was supported by the Defense Advanced Research Projects Agency (DARPA), an agency of the U.S. Department of Defense, underscoring its strategic value in both civilian and military medical applications. “Non-compressible bleeding remains a leading cause of death among soldiers before they reach a hospital, and localised treatment could dramatically improve survival rates, which was the original impetus of this research,” said Jon Mogford, a study co-author and former DARPA official.
The next phase of research will involve linking therapeutic agents to the trauma site-homing peptides and testing them in animal models before moving to early human clinical trials. The team envisions translational applications ranging from battlefield medicine to civilian trauma response and possibly even sports injuries or surgical recovery.
“We are actively developing peptide-linked drugs and imaging agents based on this discovery,” said Arap. “The traumome concept may also have applications beyond trauma, including in surgery, inflammation and tissue regeneration.”
ASB overlay is divided into five distinct sections—head and neck, upper trunk, buttocks and pelvis, thighs, and feet and heels
In combat zones and emergency rescues, rapid evacuation and treatment can mean the difference between life and death. But prolonged immobilisation during transport poses another life-threatening risk: pressure injuries.
A newly developed adaptive spine board (ASB) overlay aims to change that, offering an innovative solution to prevent pressure injuries and dramatically improve patient outcomes. Developed by researchers at The University of Texas at Arlington and UT Southwestern Medical School, the adaptive spine board sits atop a standard stretcher or spine board, using air-cell technology to redistribute pressure more effectively than traditional evacuation surfaces. The team’s newly published study in the Journal of Rehabilitation and Assistive Technologies Engineering shows the ASB outperforms other immobilisation options.
“The ability to dynamically adjust pressure so that no vulnerable body regions experience excessive weight is a breakthrough for medical evacuation,” said Muthu B.J. Wijesundara, principal research scientist at the University of Texas at Arlington Research Institute. “This innovation could set a new standard in casualty transport protocols.”
Also called bedsores or ulcers, pressure injuries result from prolonged pressure on the skin and underlying soft tissue, leading to cell death, tissue breakdown and open wounds. They are a constant risk for trauma patients during long-range transport, which sometimes lasts more than 16 hours. Research shows that more than 50% of casualties transported during the Iraq War developed pressure injuries before reaching a hospital.
While some existing technologies, such as vacuum spine boards, can help redistribute pressure, their effectiveness is limited. Many conventional supports fail to keep pressure below the thresholds recommended to prevent injury. Military stretchers and pads have shown to create high-pressure points on vulnerable areas of the body, including the back of the head, base of the spine, buttocks and heels.
“Beyond military use, the ASB overlay could prove valuable in civilian medical transport, particularly for spinal injury patients who are at high risk for pressure ulcers,” Dr Wijesundara said. “The research also highlights potential applications in other environments where prolonged immobilisation is necessary, such as disaster relief and space exploration.”
The ASB overlay features a multi-segmented air-cell design that target pressure-prone areas more effectively than previous solutions. It is divided into five distinct sections—head and neck, upper trunk, buttocks and pelvis, thighs, and feet and heels—each equipped with sensor-driven pressure modulation for responsive, localised support.
“One key innovation is the system’s ability to autonomously adjust the air-cell pressure to maintain optimal distribution for each patient,” Wijesundara said. “We developed an algorithm that compensates for environmental variables, such as temperature and barometric pressure changes, ensuring consistent performance across varying conditions. Testing showed that the ASB overlay outperformed typical equipment used in casualty transport.”
For critically injured patients, pressure injuries can significantly complicate treatment and recovery, leading to longer hospital stays, higher infection risks and additional surgeries. They’re also costly. The Agency for Healthcare Research and Quality (AHRQ) estimates that pressure injuries in the US can cost up to $151 700 per case, adding $11.6 billion in additional health care expenses annually. Alarmingly, the AHRQ also reports that approximately 60 000 patients die each year because of pressure injuries. The ASB overlay’s advanced pressure modulation could help mitigate these risks—especially for patients who cannot be repositioned during extended transport.
The research team is now planning additional studies to improve the device’s usability in real-world conditions. As the military increasingly relies on prolonged aeromedical evacuation, such advancements are critical for enhancing patient care in conflict zones.
Each year in the US alone, approximately 750 000 patients are hospitalised for sepsis, of which approximately 27% die. In about 15% of cases, sepsis worsens into septic shock, characterised by dangerously low blood pressure and reduced blood flow to tissues. The risk of death from septic shock is even higher, between 30% and 40%.
The earlier patients with sepsis are treated, the better their prospects. Typically, they receive antibiotics, intravenous fluids, and vasopressors to raise blood pressure. But now, a large cohort study in Frontiers in Immunology has shown for the first time that supplementary treatment with statins could boost their chances of survival.
“Our large, matched cohort study found that treatment with statins was associated with a 39% lower death rate for critically ill patients with sepsis, when measured over 28 days after hospital admission,” said Dr Caifeng Li, the study’s corresponding author and an associate professor at Tianjin Medical University General Hospital in China.
Statins are best known as a protective treatment against cardiovascular disease, which function by lowering ‘bad’ LDL cholesterol and triglycerides, and raising ‘good’ HDL cholesterol. But they have been shown to bring a plethora of further benefits, which explains the burgeoning interest in their use as a supplementary therapy for inflammatory disorders, including sepsis.
Not just lowering cholesterol
“Statins have anti-inflammatory, immunomodulatory, antioxidative, and antithrombotic properties. They may help mitigate excessive inflammatory response, restore endothelial function, and show potential antimicrobial activities,” said Li.
The authors sourced their data from the public Medical Information Mart for Intensive Care-IV (MIMIC-IV) database, which holds the anonymised e-health records of 265 000 patients admitted to the emergency department and the intensive care unit of the Beth Israel Deaconess Medical Center of Boston between 2008 and 2019. Only adults with a diagnosis of sepsis hospitalised for longer than 24 hours were included here.
The authors compared outcomes between patients who received or didn’t receive any statins during their stay besides standard of care, regardless of the type of statin. Unlike in randomised clinical trials, the allocation of treatments is not determined by random in observational studies like the present cohort study. This means that it is in principle hard to rule out that an unknown underlying variable affected allocation, for example if physicians unconsciously or on purpose were prone to give statins to those patients most likely to benefit from them.
However, Li and colleagues used a technique called ‘propensity score matching’ to minimize the risk of such bias: they built a statistical model to determine a likelihood score that a given patient would receive statins, based on their medical records, and then found a matching patient with a similar score, but who didn’t receive statins. In the final sample, 6070 critical patients received statins while another 6070 did not.
Despite improvements in CPR and ambulance response times, only about one in 10 people ultimately survive after out-of-hospital cardiac arrest (OHCA). Most patients hospitalised with OCHA die of brain injury, and no medications are currently available to prevent this outcome. A team led by researchers from Mass General Brigham found that immune cells may play a key role.
Using samples from patients who have had an OHCA, the team uncovered changes in immune cells just six hours after cardiac arrest that can predict brain recovery 30 days later. They pinpointed a particular population of cells that may provide protection against brain injury and a drug that can activate these cells, which they tested in preclinical models. Their results are published in Science Translational Medicine.
“Cardiac arrest outcomes are grim, but I am optimistic about jumping into this field of study because, theoretically, we can treat a patient at the moment injury happens,” said co-senior and corresponding author Edy Kim, MD, PhD, of the Division of Pulmonary and Critical Care Medicine at Brigham and Women’s Hospital. “Immunology is a super powerful way of providing treatment. Our understanding of immunology has revolutionised cancer treatment, and now we have the opportunity to apply the power of immunology to cardiac arrest.”
As a resident physician in the Brigham’s cardiac intensive care unit, Kim noticed that some cardiac arrest patients would have high levels of inflammation on their first night in the hospital and then rapidly improve. Other patients would continue to decline and eventually die. In order to understand why some patients survive and others do not, Kim and colleagues began to build a biobank – a repository of cryopreserved cells donated by patients with consent from their families just hours after their cardiac arrest.
The researchers used a technique known as single-cell transcriptomics to look at the activity of genes in every cell in these samples. They found that one cell population – known as diverse natural killer T (dNKT) cells – increased in patients who would have a favourable outcome and neurological recovery. The cells appeared to be playing a protective role in preventing brain injury.
To further test this, Kim and colleagues used a mouse model, treating mice after cardiac arrest with sulfatide lipid antigen, a drug that activates the protective NKT cells. They observed that the mice had improved neurological outcomes.
The researchers note that there are many limitations to mouse models, but making observations from human samples first could increase the likelihood of successfully translating their findings into intervention that can help patients. Further studies in preclinical models are needed, but their long-term goal is to continue to clinical trials in people to see if the same drug can offer protection against brain injury if given shortly after cardiac arrest.
“This represents a completely new approach, activating T cells to improve neurological outcomes after cardiac arrest,” said Kim. “And a fresh approach could lead to life-changing outcomes for patients.”
Updated guidance reaffirms the recommendation for cardiopulmonary resuscitation (CPR) and highlights the importance of compressions with rescue breaths as a first step in responding to cardiac arrest following drowning, according to a new, focused update to Special Circumstances Guidelines from the American Heart Association and the American Academy of Pediatrics. The recommendations were published simultaneously in Circulation (focusing on adults) and Pediatrics (focusing on children).
Drowning is the third-leading cause of death from unintentional injury worldwide. The World Health Organization estimates there are about 236 000 deaths due to drowning each year globally. According to the CDC, it’s the number one cause of death for children ages 1-4 years old in the US.
“The focused update on drowning contains the most up-to-date, evidence-based recommendations on how to resuscitate someone who has drowned, offering practical guidance for health care professionals, trained rescuers, caregivers and families,” said writing group Co-Chair Tracy E. McCallin, M.D., FAAP, associate professor of paediatrics in the division of paediatric emergency medicine at Rainbow Babies and Children’s Hospital in Cleveland. “While we work on a daily basis to lower risks of drowning through education and community outreach on drowning prevention, we still need emergency preparedness training that can be used in tragic circumstances if a drowning occurs.”
Detailed in the new guideline update:
Anyone removed from the water without showing signs of normal breathing or consciousness should be presumed to be in cardiac arrest.
Rescuers should immediately initiate CPR that includes rescue breathing in addition to chest compressions. Multiple large studies over time show more people with cardiac arrest from non-cardiac causes such as drowning survive when CPR includes rescue breaths compared to Hands-Only CPR (calling 911 [10111 in South Africa] and pushing hard and fast in the centre of the chest).
Drowning generally progresses quickly from initial respiratory arrest (when a person is unable to breathe) to cardiac arrest, meaning that the heart stops beating. As a result, blood cannot circulate properly throughout the body, and it is starved of oxygen.
“CPR for cardiac arrest due to drowning must focus on restoring breathing as well as restoring blood circulation,” said writing group Co-Chair Cameron Dezfulian, MD, FAHA, FAAP, senior faculty in paediatrics and critical care at Baylor College of Medicine in Houston.
“Cardiac arrest following drowning is most often due to severe hypoxia, or low blood oxygen levels,“ Dezfulian said. ”This differs from sudden cardiac arrest from a cardiac cause where the individual generally collapses with fully oxygenated blood.”
The updated guidance advises untrained rescuers and the public to:
Provide CPR with breaths and compressions to all people who have a cardiac arrest after drowning. If a person is untrained, unwilling, or unable to give breaths, they can provide chest compressions only until help arrives.
In-water rescue breathing should be given only by rescuers trained in this special skill if it doesn’t compromise their own safety. Trained rescuers should also provide supplemental oxygen if available.
The initiation of CPR should always be prioritised and begin as soon as possible as early lay responder CPR has been shown to improve outcomes from drowning.
The writing group recommends an automated external defibrillator (AED) should be placed in public facilities where aquatic activities are present such as swimming pools or beaches. They can be used once the person is removed from the water, if available, yet should not delay initiation of CPR. If available, the AED should be connected to the patient to assess for shockable rhythms once CPR is ongoing. Although most cases of cardiac arrest following drowning do not have shockable rhythms, if a primary cardiac event such as a heart attack occurs while in the water, the best outcomes are when defibrillation is done quickly. AED use is safe and feasible in aquatic environments.
All individuals requiring any level of resuscitation following drowning, including those who only need rescue breaths, should be transported to a hospital for evaluation, monitoring and treatment.
In addition to the recommendations on drowning resuscitation, the guideline update also highlights the Drowning Chain of Survival, which includes the steps needed to improve chances of survival: prevention, recognition and safe rescue.
Prevention
It has been estimated that more than 90% of all drownings are preventable. Research has found most infants drown in bathtubs, and the majority of preschool-aged children drown in swimming pools. The American Heart Association and the American Academy of Pediatrics recommend being water aware and practicing water safety. See: Prevention of Drowning and other guidelines.
Recognition
Recognition of drowning may be challenging because someone who is drowning may not be able to verbalise distress or signal for help. Drowning happens quickly. People in distress will rapidly submerge, lose consciousness and may be hidden from anyone not actively seeking them.
Safe Rescue and Removal
The guideline update recommends that appropriately trained rescuers, such as lifeguards, swim instructors or first responders, should provide in-water rescue breathing to an unresponsive person who has drowned if it does not compromise their own safety. Previous studies have proven this leads to more favourable survival outcomes. A drowning person who is unconscious and likely in cardiac arrest should be removed from the water in a near-horizontal position, with the head maintained above body level and airway open. If the drowning individual is conscious, a more vertical position may be preferable to reduce the risk of vomiting.
In summary, “These updated guidelines are based on the latest available evidence and are designed to inform trained rescuers and the public how to proceed in resuscitating people who have drowned. Drowning can be fatal. Our recommendations maximise balancing the need for rapid rescue and resuscitation, while prioritising rescuer safety,” Dezfulian said.
The sooner a lay rescuer (bystander) starts cardiopulmonary resuscitation (CPR) on a person having a cardiac arrest at home or in public, up to 10 minutes after the arrest, the better the chances of saving the person’s life and protecting their brain function, according to preliminary research to be presented at the American Heart Association’s Resuscitation Science Symposium 2024.
Cardiac arrest, which occurs when the heart malfunctions and abruptly stops beating, is often fatal without quick medical attention such as CPR to increase blood flow to the heart and brain. More than 357 000 out-of-hospital cardiac arrests happen each year in the US, with a 9.3% survival rate. “Our findings reinforce that every second counts when starting bystander CPR and even a few minutes delay can make a big difference,” said first author Evan O’Keefe, MD, a cardiovascular fellow at Saint Luke’s Mid America Heart Institute and the University of Missouri-Kansas City. “If you see someone in need of CPR, don’t dwell on how long they’ve been down, your quick actions could save their life.”
The study analysed nearly 200 000 cases of witnessed out-of-hospital cardiac arrest to determine whether initiating CPR within different time windows, compared to outcomes with no bystander CPR administered, made a difference in survival and brain function after hospital discharge.
“We found that people who received bystander CPR within the first few minutes of their cardiac arrest were much more likely to survive and have better brain function than those who didn’t,” O’Keefe said. “The longer it took for CPR to start, the less survival benefit one received. However, even when CPR was started up to 10 minutes after cardiac arrest, there was still a significant survival benefit compared to individuals who did not receive CPR from a bystander.”
Results also found:
People who received CPR within two minutes of out-of-hospital cardiac arrest had an 81% higher rate of survival to release from the hospital and 95% higher rate of surviving without significant brain damage compared to people who did not receive bystander CPR.
Even people who received bystander CPR up to 10 minutes after cardiac arrest were 19% more likely to survive to hospital discharge and 22% more likely to have a favorable neurological outcome than those who did not receive bystander CPR at all.
For those who did not receive bystander CPR, about 12% survived to be released from the hospital, and more than 9% survived without significant brain damage or major disabilities. When bystander CPR was initiated more than 10 minutes after cardiac arrest, bystander CPR, compared to not receiving the lifesaving assistance, was no longer associated with improved survival.
“These results highlight the critical importance of quick action in emergencies. It suggests that we need to focus on teaching more people how to perform CPR, and we also need to emphasise ways to get help to those suffering cardiac arrest faster,” O’Keefe said. “This might include more widespread CPR training programs, as well as better public access to automated external defibrillators (AEDs) and improved dispatch systems.”
O’Keefe noted that future research could explore how technology (like apps that alert nearby trained bystanders or alert dispatchers to likely cardiac arrest) may help to reduce the time to first intervention, information that could be important for emergency dispatchers and policymakers in the development of public interventions for cardiac arrest.
“This study highlights the need for prompt recognition and treatment of cardiac arrest by bystanders. Time is of the essence when a cardiac arrest occurs, and late interventions can be as ineffective as no intervention. Community education and empowerment are critical for us to save lives,” said American Heart Association volunteer expert Anezi Uzendu, MD, an interventional cardiologist at the University of Texas Southwestern Medical Center in Dallas and a cardiac arrest survivor.
A limitation of the study includes that the average time of arrival for emergency medical technicians (EMTs) to the person having cardiac arrest was roughly 10 minutes. This means that in this study, the people who received bystander CPR 10 minutes after their cardiac arrest were likely being compared to a group receiving professional medical attention.
Study details and background:
The study identified 160 822 witnessed out-of-hospital cardiac arrests that occurred from 2013-2022. Among the people whose data was analysed, the average age was 64 years old and about 34% were women.
Researchers used data from the Cardiac Arrest Registry to Enhance Survival (CARES), a national, web-based health registry focused on helping communities improve care for and survival of out-of-hospital cardiac arrest.
The research categorized time to initiation of bystander CPR in two-minute intervals and analysed the link between each time interval, compared to the group who did not receive CPR, with survival to hospital discharge and favourable neurological survival, or surviving with minor disabilities.
Researchers from Sergio Arboleda University in Colombia and the Georgia Institute of Technology in the US used an electrophysiological computer model of the heart’s electrical circuits to examine the effect of the applied voltage field in multiple fibrillation-defibrillation scenarios. Their research, published in the interdisciplinary journal Chaos, discovered that far less energy is needed than is currently used in state-of-the-art defibrillation techniques.
“The results were not at all what we expected. We learned the mechanism for ultra-low-energy defibrillation is not related to synchronisation of the excitation waves like we thought, but is instead related to whether the waves manage to propagate across regions of the tissue which have not had the time to fully recover from a previous excitation,” author Roman Grigoriev said. “Our focus was on finding the optimal variation in time of the applied electric field over an extended time interval. Since the length of the time interval is not known a priori, it was incremented until a defibrillating protocol was found.”
The authors applied an adjoint optimization method, which aims to achieve a desired result, defibrillation in this case, by solving the electrophysiologic model for a given voltage input and looping backward through time to determine the correction to the voltage profile that will successfully defibrillate irregular heart activity while reducing the energy the most.
Energy reduction in defibrillation devices is an active area of research. While defibrillators are often successful at ending dangerous arrhythmias in patients, they are painful and cause damage to the cardiac tissue.
“Existing low-energy defibrillation protocols yield only a moderate reduction in tissue damage and pain,” Grigoriev said. “Our study shows these can be completely eliminated. Conventional protocols require substantial power for implantable defibrillators-cardioverters (ICDs), and replacement surgeries carry substantial health risks.”
In a normal rhythm, electrochemical waves triggered by pacemaker cells at the top of the atria propagate through the heart, causing synchronised contractions. During arrhythmias, such as fibrillation, the excitation waves start to quickly rotate instead of propagating through and leaving the tissue, as in normal rhythm.
“Under some conditions, an excitation wave may or may not be able to propagate through the tissue. This is called the ‘vulnerable window,’” Grigoriev said. “The outcome depends on very small changes in the timing of the excitation wave or very small external perturbations.
“The mechanism of ultra-low-energy defibrillation we uncovered exploits this sensitivity. Varying the electrical field profile over a relatively long time interval allows blocking the propagation of the rotating excitation waves through the ‘sensitive’ regions of tissue, successfully terminating the irregular electric activity in the heart.”
There is no difference in the effectiveness of the two most commonly used methods for administering medication during out-of-hospital cardiac arrest, according to a large new clinical study published in NEJM.
This is shown in a large new clinical study from Aarhus University and Prehospital Services, Region Midtjylland, which compared two ways of accessing the bloodstream: a standard needle in a vein (venous catheter) and a so-called intraosseous needle, which is inserted into the bone marrow.
“When a person suffers cardiac arrest outside the hospital, it is crucial to quickly access the bloodstream to administer life-saving medication. We investigated which method is best,” explains Lars Wiuff Andersen, professor and physician at the Department of Clinical Medicine, Aarhus University, Prehospital Services, Region Midtjylland, and Aarhus University Hospital.
Venous catheter or intraosseous needle?
Until now, healthcare professionals have preferred using a venous catheter, but it can be difficult to place as veins may collapse during cardiac arrest.
The intraosseous needle, inserted either into the shinbone or upper arm, can be faster and easier to use in an emergency.
Therefore, it’s interesting to investigate the effectiveness of both methods, explains Lars Wiuff Andersen.
The study, based on data from nearly 1500 cardiac arrest patients across Denmark, showed that about 30 percent of patients in both groups had their blood circulation restored.
“The two methods proved to be equally effective in restoring blood circulation and saving lives. There was no difference in the patients’ survival or quality of life,” explains Mikael Fink Vallentin, associate professor at the Department of Clinical Medicine and Prehospital Services, Region Midtjylland, and co-lead author of the study.
May change guidelines
According to the researchers behind the study, the results may impact future guidelines, which previously recommended venous catheters as the first choice.
However, Lars Wiuff Andersen notes that it is too early to say exactly how the guidelines will change.
“Our data must be considered alongside a large clinical trial from the UK, which is being published simultaneously with our study. Combined, these two trials will likely influence guidelines for cardiac arrest treatment, but a thorough review of the results will be needed,” he says.
More unanswered questions
There are still several unanswered questions, especially regarding whether specific groups of cardiac arrest patients benefit more from one method than the other.
The researchers are continuing to analyse and compare their own data with data from the UK trial.
The Danish research team has already planned a new, large clinical trial to investigate which method is best for delivering electric shocks during cardiac arrest.
“We hope to gain even more answers on how to best save lives in cardiac arrest in the future,” says Lars Wiuff Andersen.
