So, thank you for this opportunity. My name is Tina Chen. I am at UCSF now. Preparing this talk, one of the things that I think most of us in this room, we care a lot about critical illness. And you're here because you are curious and care about climate change as well. But these two oftentimes, you know, on paper, you don't think that they're related. And I wish for the next 15 minutes, I'll try to convince you that climate change and sepsis and the care of critical illness is very much related. I have no disclosures. So as our environment change, our host response is going to change. Vector behavior will also change. There's going to be increased pathogen burden. Antibiotic resistance is rising, as well as with climate change, there is significant change in our supply chain that will affect how we take care of these patients. So hot and wet climate changes disease pattern. We know that temperature and wet climate will impact how vectors, such as mosquitoes, mice, ticks and pathogen matures, replicate and transmit diseases. I'm giving you an example from 2018 in Europe, where there was a really cold and wet late winter and early spring, noted by the blue color down here, followed by the very hot late spring and summer. With drought, there was limited water source. And with single water source, your birds and your mosquitoes are congregating together in single source. With close proximity, there is exchange of disease. Indeed, in 2018, which represented in the red line for West Nile virus reporting, it's much earlier and with higher incidence compared to previous years. So it's alarming that, you know, with these warming climate, we're going to have increased vector-borne diseases. The other good example is enteric infections with climate change. So this pool study of 40-some studies of diarrheal infection, they found that with every just one degree Celsius change, we increase the risk of diarrheal infections, with salmonella being the highest risk of 15% increase just with one degree. On the other hand, I guess in some way it's a saving grace that the viruses risk decrease with warming temperature. They found that in colder climates, viruses actually stay detectable for much longer. Antibacterial resistance is also rising with rising temperature. We know that with increased temperature, there's increased gene transfer between bacteria. There's also change in human behavior with extreme climate events. There are increased crowding, there's increased host contact, and obviously there's increased use of antibiotic, which could also induce antibacterial resistance. One thing that I learned was eutrophication process, which is an over-nutrition runoff into our water source, which creates a very nutrient-rich water for algae to grow and die. And with this, we have overgrowth of bacteria that allows a harboring more antibiotic resistance. I want to credit this slide to my good friend, Dr. Kadir, about sewage, right? So we know that sewage is a known antibiotic-resistant reservoir, and with increased climate events, we have increased flooding, and that allows this fluid to be in contact with our daily living at this point. There's also seasonal and temperature variation in the risk of sepsis. I'm going to show you an example of both GI, GU, as well as pneumonia infections that's affected by temperature and season. In a Japanese study looking at a presentation to the emergency room, they saw that there is variation by seasons with acute abdominal complaints, appendicitis being highest in the summer, acute cholecystitis, and diverticulitis as well. In a similar study by another Japanese group, I'm showing you winter in the gray color. I guess this is not translating as well as I like. Winter in gray, spring in green, summer in blue, and fall in yellow. That in the warmer months, spring and summer, you have increased incidence of acute cholecystitis. In respiratory infections, similar pattern with seasonal changes is seen as well. Instead of having more pneumonia in the warmer climates, pneumonia and respiratory infections are more prevalent in the colder months, represented in gray and brown. In the same study done in the US using ICD code for discharge diagnosis, GU sepsis was more frequent in the summer months. A Spanish study showing, again, similar things that exposure to high heat and high humidity within two weeks of exposure increased the risk of pneumonia-related sepsis. This study also showed that older adults are at higher risk. This one I found particularly interesting for us as ICU practitioner. So they looked at blood-borne infection in the ICU, and this is a study done in Germany. So it's not necessarily people presenting from outside. It's actual infection that occurs in the ICUs based on ambient temperature outside the hospital. Here they found that they broke the temperature down by their reference value at 5 degrees all the way up to greater than 20 degrees. And for all the pathogen blood-borne infections for gram-positive, negative, and fungal, the risks all increase as the temperature goes up, almost all of them, except for streptococcal pneumonia bacteremia. This is the one that with temperature increasing, there's actually drop in infection. The other thing that's interesting to note that from this study, the higher temperature mark is at greater than 20 degrees, and the reference is at 5 degrees. So if we're thinking about a global setting, 20 degrees in some other country would be a normal temperature. So this is something to keep in mind. There's also a usually attributable mortality to ambient temperature exposure of a study published in LENSA looking at 13 cities comparing very temperate, cold, and hot climates, including my home city, Taiwan, Taipei, that the colder temperature, extreme temperature definitely has attributable mortality. But the main thing is that colder days have a relationship that's slow at study compared to a hot temperature exposure. The solid line here is marking an optimal temperature where the mortality is the lowest, and when you move away from the optimal temperature on the colder end, cold days has 7.9 attributable mortality and the hotter days are 0.42. The striking part is really heat exposure increase the mortality much faster in a nonlinear fashion. So what happened to people in extreme heat and humidity exposure? This interesting study looking at exposure to cyclones and hurricanes in the US. So cyclones and hurricanes are similar. They're basically giant storm system, but the difference is based on their wind speed, and it's a system developed in the Atlantic Ocean. So the study looked at 30 years for every county that has at least one event. They found that tropical cyclones and hurricanes are associated with increased mortality by different diagnostic group except for cancer. So this group shows cancer, cardiovascular disease, infectious and parasitic injury, neuropsychiatric and respiratory, with injury at the month of exposure being the highest risk with increased almost up to 35% increase in mortality by this diagnosis. Tropical cyclones and hurricanes are also associated with increased infection and respiratory-related death. So in infectious disease side, cyclone increased infectious-related death by 1.8% in one month following exposure, and if there is one day of hurricanes, the risk of infectious disease goes up by 11% by two months after exposure. On the respiratory disease side, both hurricanes and cyclone increased risk in the first one month after exposure, and the increase is 1.3%. For cyclone exposure and for hurricane exposure, it's up to 8%. Extreme heat is also related to hospital admission in older adults. I'm not expecting you to read the slide. In this study, they looked at heat wave that was defined by two consecutive days with temperature exceeding the 99th percentile in that particular county, and this is a study done in the US. They saw that cost-specific risk for hospital admission for older adults, most of them had electrolyte abnormality, renal failure, urinary tract infection, sepsis, as well as heat strokes. There are factors associated with better mortality in heat wave exposure. So the factors that increase our risk in a heat wave would be someone who's unable to care for oneself, someone who's confined to bed, someone who doesn't leave home and have multiple comorbidity, including cardiovascular disease, pulmonary disease, mental illness. And I found it interesting that someone who takes psychotropic medication actually also has increased risk of mortality in a heat wave exposure. I think overall, the thinking process is these people cannot seek shelter from heat. Things that lowers our risk for mortality in a heat wave are people with good social contact, someone who has access to air conditioning either at home or be able to visit someplace that has that ability. Unfortunately, heat wave alerts actually does not change mortality. There's a study looking at a match study from days with heat wave alert versus non-heat wave alerts. It increased our presentation to the hospital, admission to the hospital, but does not decrease overall mortality for older adults specifically. So climate change not only changed how hosts and pathogen respond. It also changed supply chain. Climate change disrupted supply chain, and I think most of us have experienced in 2017 with Hurricane Maria hitting Puerto Rico, there was a shortage of small IV bags. I remember we had limited fentanyl as well as certain antibiotics. With that, up to 50% of US hospital had shortage of these IV bags. So not directly related, Emily et al. did show that a shortage in medication such as norepinephrine could affect how we take care of septic patient. And here in the hospital that had shortage of norepinephrine, we're more likely to use phenylephrine, and they actually had increased mortality in these septic shock patients. So I think even though this is not directly showing a climate impact on sepsis, but the fact that with extreme climate event, we'll have supply chain disruption leading to how we treat patient, and that will also change the outcome of these septic patients. So in summary, I want to say that season and temperature both affect our host response and pathogen patterns. These extreme events will increase morbidity and mortality of our patients. It does increase risk of infection, and it also disrupts supply chain that ultimately will affect how we manage diseases. Is there hope? I was tasked to be able to not end this talk with this whole gloomy feel. There is some hope, right? I think yesterday there was a great talk on climate change and impact of critical care. We need to start thinking about the waste that we generate in the ICU and how we can mitigate that. In the past 10 years, there's also a lot of increase in interest and literature for both climate-related health and how climate change affects infections. And ultimately, if we could identify risks, understand the risks, mitigate the risks, hopefully we'll decrease the impact. And ultimately, just to remind ourselves, reduce, reuse, and recycle. Thank you very much.

climate change

critical illness

sepsis

vector-borne diseases

enteric infections