Coda Change

How do you diagnose death? In Critical Care we deal with death on a regular basis and although it seems black and white, that is often far from the truth. Patricia Gerritsen discusses what it means to be dead and how that knowledge can aid you in stopping a resuscitation effort. Patricia presents the degrees of death in her eyes as: Soon to be dead Reversibly dead Irreversibly dead Reversibly, irreversibly dead Changes occur following death that can be proof of death. But not always. Pallor mortis, algor mortis, rigor mortis, livor mortis and decomposition can all indicate someone has died. There are other clues that can indicate a person is either dead or will soon be dead – with minimal chance of any life saving intervention. The varying ways death presents itself poses a challenge for the clinician. This is especially true when deciding when to stop a resuscitation effort. Consider the reversibly, irreversibly dead – also known as the Lazarus phenomenon. These patients achieve return of spontaneous circulation AFTER the resuscitation effort has been stopped. There are over 50 cases in the literature, with a wide and unpredictable array of clinical situations. Therefore, the question becomes - what are the limits that can be survived? Patricia suggests that we must know the extreme limits in order to make an educated decision about resuscitation. Patricia details some of the most extreme stories of survival in the literature. Submersion has been survived after 66 minutes in a child. An individual survived being in an ice stream after 40 minutes, with a recorded temperature of 13.7 degrees. A man with a potassium of 14 mmol/L made a good recovery. There is a case of someone with a pH of 6.33 recovery fully and someone surviving a CO2 level of 375mmHg. Patricia highlights these extreme examples to show what is possible whilst acknowledging the decision to stop resuscitation is a difficult and nuanced one. When to Stop Resuscitation in Critical Care: Patricia Gerritsen For more like this, head to our podcast page. #CodaPodcast  

Diagnostic medicine is not simple – Casey Parker discusses the finer points of the diagnostic process in critical care. Diagnosis is not black and white. The world is not black and white. It is all shades of grey and about probability. One tool that clinicians have to deal with probability is Bayes’ theorem. Since it was first described in 1763 Bayes’ theorem has been applied, rejected, and rediscovered in many fields. Its use in medical diagnostics is a relatively recent phenomenon. This talk will review the history of Bayes in medicine. Since 1763 the medical world has made dramatic leaps forward. However, Bayes’ theorem still has its place. It has been made more accessible with nomograms and more recently handy clinical decision-making tools in the form of smartphone apps. Casey helps you put all this together by elaborating on the diagnostic process. Firstly, is the pre-test probability – how likely is a disease in any given population. Not all populations are the same. Therefore, depending on where you work, you need this into account when assessing patients. How do we arrive at pre-test probability? Casey details the three ‘G’s. Gut feeling, gestalt, or guess work. Secondly, are likelihood ratios. These exist independently of the population and can be described as a marker of signal to noise. For example, when a radiographer tells you there is a PE on a CT, this is not strictly true. Rather there is a chance of a PE. Next Casey discusses choice of tests. He stresses - do the test with the highest diagnostic yield. For instance, in a young female with abdominal pain you may consider a diagnosis of appendicitis or pelvic inflammatory disease. Blood tests and ultrasound will not help you in this case. A laparoscope is the diagnostic tool of choice in this case. Finally, the post-test probability – where the rubber meets the road. Where probability is converted into action. Consider the threshold to treat. This should be determined by three factors: 1. How bad is the disease? 2. How good or bad is the treatment? 3. How bad/dangerous is the test? Join Casey as he challenges you on diagnostics in critical care. Diagnostics in Critical Care: Casey Parker Finally, for more like this, head to our podcast page. #CodaPodcast

Kate Prior conveys the lessons she has learnt working as a doctor as part of the Medical Emergency Response Team (MERT) in Afghanistan. “Unexpected survivors” are those patients who, according to their injury severity score, should die of their injuries but they survive against the odds. The years of conflict in Afghanistan saw increasing numbers of these grievously injured patients surviving to live a fulfilling life. How was this achieved? As Kate explains, it is sometimes necessary to reorder the ABCDE. In the case of a major trauma with catastrophic bleeding, stopping the bleeding needs to be prioritised above all else. Kate describes the methods she used. Secondly, she discusses the importance of taking the hospital to the patient. Kate talks about the capability of the Chinook helicopters she worked in. In her words ‘helicopters become flying Emergency Departments’. This enables advanced assessment and interventions to be delivered on scene. This includes IO access, blood transfusion, RSI and high-quality analgesia. Kate goes on to discuss the important of training and rehearsal. For her role, many months of training are essential, to prepare for the unpredictable nature of a warzone. This extends to being extremely familiar with all protocols, equipment, and machines, so that it becomes second nature in all situations. Finally, Kate touches on the human impact of the patients she treated. Although you cannot save everyone, there is a need to learn a lesson from every patient. Learn from them and disseminate the knowledge. In this way, you can continue to get better. This is highlighted by the improved mortality rates in Afghanistan. For more like this, head to our podcast page. #CodaPodcast

Peer review is at the heart of science. Yet, as Richard Smith explains in this talk, there are many problems with peer reviewed research. As Richard argues, peer review is not an evidence-based process, but rather a faith-based process. Is it time for something different? Peer review has two main functions: 1) Quality assurance and 2) Improving what is published. However, with that in mind, there is no evidence of effectiveness of peer review, and lots of evidence of its ineffectiveness. This is along with peer review being slow, expensive, wasteful, inefficient, prone to bias and being largely irrelevant! Richard discusses a few of the main issues as he sees it. For example, studies in large journals are more likely to be wrong when compared to smaller journals. Some argue that the vast majority of research is a waste of time. Similarly, replication is also a major problem, as Richard explains. A huge number of studies cannot be replicated, raising questions about the initial research. What is published in journals should not be taken to be truth but rather “provisional truth”. Richard tells the tale of planting errors in articles and seeing if they are picked up by peer-review. Far more often than not, they are not! On top of this, there is fraud and theft that occurs in the peer review process. Bias exists both positively and negatively. To top it off, much of the time the process does not pick up the errors (or fraud) in papers. A lot of problems and few answers. And it is not necessarily a case of it being the least “bad system” for this process anymore. There has been attempts to improve peer review. Blinding of reviewers to authors has been shown to be ineffective. An open system did not make much difference to the quality of opinion. Checklists and training have likewise been trialled and moved past due to ineffectiveness. Finally, the process has been made as open as possible, and in real time where possible. Richard argues that we may no longer need peer review. In the age of the internet, why would a peer review process be needed when an enormous number of people can access and critique the evidence simultaneously. Journals may be yesterday’s way of publishing data. For more like this, head to https://codachange.org/podcasts/ 

The exposure of fabricated numbers in published papers by eagle-eyed readers has been due to sporadic serendipity. I am going to describe a semi-automated method that you can take away with you to do some sleuthing. I am going to describe what I found when I analysed over 4500 papers.

Jeff Drazen delivers a powerful message on the use of medical evidence in critical care. Medicine is powered by knowledge, but how do we know what is true and what is not? How do we deal with uncertainty in a setting where outcomes are not closely related to known variables? For example, although there are a few people who have survived jumping or falling from an airplane at high altitude, it is a rare event. Thus, a test to determine how to prevent death from such a disaster would only take a small number of participants to see if a particular method works. In contrast, when considering a medical condition where a large fraction of people might seemingly “recover” without treatment, such as tuberculosis, how does one determine if a treatment is effective? In this talk Jeff discusses the trials surrounding blood glucose control in the Intensive Care Unit (ICU). The way we have dealt with increased blood sugar levels in critical care has changed over time. Whereas once upon a time there was little thought given to high blood sugar levels, this changed in the 90s. One single centre paper was the catalyst for a move toward tighter glucose control for patients in ICU. Due to the novel question and well-designed study, this paper was published in a prestigious journal – even if there were questions surrounding its validity. Larger, multi-centred papers were not published until many years later due to normal logistical and financial constraints. In the interim, the initial data had informed policy. Therein lies the problem. Join Jeff as he highlights the benefits and potential pitfalls in medical research by telling the story of tight blood glucose control in the ICU. For more like this, head to https://codachange.org/podcasts/ 

Medicine is powered by knowledge, but how do we know what is true and what is not? How do we deal with uncertainty in a setting where outcomes are not closely related to known variables? For example, although there are a few people who have survived jumping or falling from an airplane at high altitude (http://zidbits.com/2010/12/can-you-survive-a-freefall-without-a-parachute/), it is a rare event. Thus, a test to determine how to prevent death from such a disaster would only take a small number of participants to see if a particular method works. In contrast, when considering a medical condition where a large fraction of people might seemingly "recover" without treatment, such as tuberculosis (http://www.who.int/mediacentre/factsheets/who104/en/print.html), how does one determine if a treatment is effective? In this talk, I will examine how we gained knowledge about tuberculosis as an example of a disease where a combination of observational scientific findings and clinical trial data are linked to advance knowledge. I will also discuss other examples of clinical trials challenges and the solutions to these challenges.

Michael Perlmutter guides you through the prehospital diagnosis and treatment of sepsis. Sepsis is a difficult diagnosis to make. Even in the hospital, where a plethora of tests are available to assist the clinician. The diagnosis remains a challenging one, due to the very nature of sepsis. A shadowy shape-shifter notorious for its ability to hide in plain sight. For now, even in-hospital, there is no test with perfect sensitivity or specificity for sepsis. This is especially true in the prehospital environment, where we must rely on tools we can bring into the field: physical exam, point of care tests (lactate/venous gas), assessment of end-tidal CO2, and ultrasound. The aim of prehospital sepsis care is two-fold – early diagnosis and early treatment. First, early diagnosis of cases ranging from early sepsis to septic shock. Point of care testing is essential. Measurement of EtCO2 serves two purposes: as a reasonable surrogate for lactate and providing an accurate respiratory rate. A vital sign that is notoriously poorly assessed. Respiratory rate plays a key role in both SIRS and SOFA/qSOFA criteria for sepsis, making an accurate count essential. Ultrasound should also play a pivotal role in prehospital sepsis management. Much has been made of the prehospital FAST exam, however, the ability of POCUS to gauge fluid responsiveness and cardiac function is far more useful. Assessment of the IVC may aid in determining the value of volume resuscitation by helping to identify patients who are responsive to volume and those who would be better served by early initiation of vasopressors. Similarly, assessment of cardiac function may prove extremely useful in selecting a pressor. POCUS may also assist in differentiating sepsis from other aetiologies by identifying a source, such as pneumonia. The second fundamental aim is treatment equivalent to that available in-hospital. This includes judicious administration of balanced IV fluids guided by POCUS and clinical assessment of fluid responsiveness, early pressors, and early antibiotics, particularly where transport times are significant. When sepsis is diagnosed by EMS, a “sepsis alert” should be communicated to the receiving hospital, to facilitate ongoing early, aggressive care upon arrival of the retrieval team. Advanced prehospital diagnosis and treatment can produce dramatic reductions in mortality from sepsis. For more like this, head to our podcast page. #CodaPodcast

Endothelium was once thought to be an inert organ. However, it plays an important role in multiple functions. These include coagulation, inflammation and determination of vascular permeability. He then gives a brief overview of the endothelial arrangement, function of the glycocalyx layer and how an injury causing a loss of the protective layer results in holes in the endothelium. The inflammatory cells enter via these holes and causes oedema in the affected organs leading to multiple pathologies. Danny then explains the role of endothelium in controlling cell barrier function. Activation of cortactin protein and the myosin light-chain kinase (MLCK) enzymes activate stress fibres resulting in pulling of endothelial cells thereby increasing its permeability. Danny discusses the role of endothelial dysfunction in acute respiratory distress syndrome (ARDS) at macrovascular, microvascular and molecular levels. Macrovascular thrombosis is related to an increase in severity of ARDS, pulmonary hypertension, and mortality. At a microvascular level there is a loss of vascularity and increased blood vessel thickness. At a microscopic level, endothelial cells appear swollen and damaged in ARDS. Endothelial dysfunction drives organ dysfunction and mortality. Changes in various endothelial markers like increased von Willebrand factor (vWF), decreased protein C and increased pulmonary dead space correlate with increased mortality. Studies show that endothelial dysfunction is a more specific and sensitive method to predict mortality of critically ill patients when compared to SOFA score, SAPS 2 score and WCC. Danny discusses ventilator strategies for endothelial cells in ARDS patients. Lowering the tidal volume of ventilators and employing recruitment manoeuvres are such strategies. Both of these cause a decrease in oedema by reducing endothelial permeability. He then shares the various potential pharmacological treatments for treating endothelial damage. These include statins and spingosine-1-phosphate (S1P). Different studies on the effect of statins in ARDS show contradicting result. However, targeted therapies can be designed by studying the phenotypes and molecular basis of ARDS in each patient. The role of the endothelium as a mediator of critical illness by Danny McAuley Finally, for more like this, head to our podcast page. #CodaPodcast

Bill Knight explains the concept of death by neurological criteria and the complexities surrounding organ donation in such situations. Bill discusses the process of dying, the definition of death, how to approach the neurologically dead patient and how to consider organ donation. Death is a complex topic. Due to advancements in medical technology and processes, the definition of death is a challenging one. Bill talks at length about the definition of death by the neurological criteria. Dying is an active process, whereas death is an event. The acceptance of death by the neurological criteria is often challenging as Bill will highlight. Bill talks about the care of the dying or dead patient. There is a point at which care will transition from supporting the patient to supporting the organs. This is still good care. There is an alignment of parallel intentions – first and foremost resuscitation of patients and then failing that, proceeding to considering and actioning organ donation. This is important due to the shortage of viable donor organ worldwide. The donation process itself is complex. Bill provides his thoughts. He insists that an intensivist be involved as this has been shown to increase the number of viable and healthy organs made available. The timing is also important. Available evidence does not support the need for immediate procurement after brain death. Taking time to optimise perfusion and allow recovery and cardiac function is appropriate and should be done. Bill also discusses other treatment options at the time of death such as optimising endocrine function. Finally, Bill will provide some practical considerations when communicating with the dead patient’s family. This involves being clear on your messaging. You are supporting organs, not life. To reinforce this point, Bill suggests not examining or talking to the patient. He also recommends using all of the available hospital support services. Similarly, it is best to not introduce the topic of organ donation to the family yourself as the treating clinician. Utilise the Organ Procurement Organisations (or similar services) and get them involved early to speak with the family. Join Bill Knight in his talk on the North American perspective on Organ Donation, brain death and management of the brain dead donor prior to organ donation. For more like this, head to our podcast page. #CodaPodcast