Disclaimers for Vignettes Disclaimers This website is provided for educational and informational purposes only and although every effort has been made to present accurate information, this is not a substitute for professional advice. Always seek guidance from a qualified healthcare provider or physician for inquiries regarding medical conditions, treatments, or before embarking on any new healthcare regimen. Never disregard professional medical advice or delay in seeking it due to information found here. If you think you may have a medical emergency, call 911 or go to the nearest emergency room immediately. No physician-patient relationship is created by use of this website. The practice of medicine relies on using the best available evidence, but clinical scenarios often lack clear-cut answers. Every clinical situation is unique, and no single solution applies universally. Clinical guidelines attempt to provide recommendations that apply in most situations, but that are not one-size-fits-all solutions and they do not replace clinical judgment. The infinite variety of patient, disease, and environmental factors influencing clinical decision-making cannot be fully accounted for in medical literature. Therefore, any variance in the approach of physicians from what is presented here does not necessarily signify an error on their part. Some of the images on this website contain graphic content that may be disturbing or distressing to some audiences. Viewer discretion is advised. HIPPA- vignettes are presented to provide clinical education, with considerable care to prevent any patient from being identified. Protected health information and patient identifiers (name/ location/ date/ occupation/ contact information/ identifiable photos/ numerics such as SSN/MRN/insurance) have been withheld. Unique details have been removed from text and images. Details that don't impact the clinical case, such as age and gender, have been modified to obscure each patient's identity. Many stories are heavily modified to highlight the key learning points and some scenarios are complete fabrications. The scenarios span my entire 17 years of experience in the medical field, and they are seen on a routine basis in our field. I have not shared one-of-a-kind or sensational cases because the risk of disclosing identifiable details heavily outweighs any potential educational benefit. The views, opinions, and assertions expressed herein are those of the author and do not reflect the official policy or position of the Department of Defense. These scenarios are not designed to portray the comprehensive evaluation and management of acute care surgery patients. Many common steps are omitted, as the intent is to highlight unique learning points for different clinical scenarios. Trauma scenarios DO NOT teach all the basic principles of ATLS, so there is a minimal repetition of basic principles (primary and secondary survey). Any of the products found on this website are not specific endorsements. I do not receive any monetary compensation or non-monetary incentives for the sale of any items seen here.

Places to Go, Things to Do Bucket List Places to Go, Things to Do Places I Want to Visit The Narrows- Zion National Park Apostle Islands National Lakeshore Spain (went as a kid, want to go back) √ Grand Canyon Mexico Alaska Europe Machu Picchu (Peru) Australia Hawaii √ Adventures I want to Experience Watch a Bruins game at TD Gardens in Boston Hang-gliding Backcountry camping Snowboard in Canada and Europe Horseback ride on the beach Eat at a Michelin 3-star Restaurant Things I Want to Accomplish Donate blood √ Become fluent in Spanish Start a charity Own a house in Boston Own a horse ranch Own a dog Publish something non-medical Fears to Overcome Speak in front of a large audience (EAST conference, AAST conference) √ Experiences I don't care to repeat, but glad I did them once Tough Mudder Eaten alligator and shark Things others want to do that I have no desire to do Skydiving Scuba diving Attend the Masters Previous Next

Surgery trainee education. Trauma surgeon. Acute Care Surgery. FAQs Why did you make this website? Over these years of learning about the practice of surgery, I've also learned a lot about myself. I am not an expert, and I did not follow a typical pathway- but I have some knowledge and resources to share. As I transition into my new Acute Care Surgeon role after 17 years in training, I'm pausing to share my experience, tips for success, and random nuggets of wisdom. This will be a work in progress, and I look forward to seeing how it evolves. My goal is to share my experience and knowledge in the hopes of helping those who desire to follow this path. But why do we need another medical education website? There are so many good resources already... There are endless ways to explain clinical concepts- pictures, text, analogies, clinical cases, podcast discussions of cases or principles, review articles, etc. There are also different learning styles. When I was trying to grasp advanced ventilator management, I read basic critical care textbooks, a book dedicated solely to ventilator management, and various websites and journal articles. This website is another way to interact with the information. Hopefully you will understand some of the concepts in a new way that helps you remember and apply them in clinical scenarios. In addition, I have also tried to create a comprehensive collection of all the useful resources I know, like apps and open access medical education resources (websites, clinical guidelines, etc) in one place for trainees to What does Doc on the Run mean? The summer before my last year of medical school was the start of my running career. My focus was enjoying the outdoors, not pace or distance. During my residency, I met someone who helped me refine my running. I started timing myself, training, and racing. Within a year or two, I pushed through personal barriers to become a "runner." My first half marathon was on Thanksgiving in my third year of surgical residency. I am at the end of my formal training, I am now an Acute Care Surgeon. As a surgeon, there are numerous factors that I can't control. It's fast-paced, demanding, and dynamic. I enjoy the organized chaos and high-stakes cases. Running is key to my work-life balance. Unlike in the operating room or the trauma bay, I have control over most aspects of my runs- pace, distance, route, and thoughts. It's not chaotic- it's basically the polar opposite of my work. During the day, my mind is going a million miles an hour. When I run, everything becomes clearer- I can solve problems, mull over ideas, or process dilemmas. And perhaps the most concrete impact is the runner's high that I enjoy after finishing. I have continued to run 10Ks, 10 milers, and the occasional 5K or 15K. I have learned more about the science of running (HR training zones, different paces for tempo/ interval/ long runs/ short runs) and I've learned how to adapt training schedules to fit my life. Unfortunately, I have suffered my share of injuries, including most recently nerve impingement in my foot. While I may have scaled back, running will always be part of my identity. Did you really build this website yourself? Yes, I did. No, I didn't do all the intricate coding by myself. But I did design, format, and create the content. So are you a computer/ technology guru? Whatever I know about technology, I learned from my brother and from spending many hours researching problems online. While my parents might consider me an expert, I literally just search online to solve most issues. When I get to the end of the internet and still haven't found the solution, my next step is Apple tech support (obviously only if the problem is with my iPhone or Mac). What did you learn while making this website? - Formatting the working space on a website - URL redirect - Domains and subdomains - Search engine optimization (SEO) - Establishing custom domains - Which text/ background colors are easiest to read - Anchors If you weren't an Acute Care Surgeon, what would you do? I'd be a chef. I love cooking! Is there anything that is overwhelmingly gross in your job? I have had almost every body fluid on me- stool, urine, blood, etc. So very little grosses me out. But I can't stand oral or nasal secretions (aka saliva, slobber, snot, etc.).

< Back Ultrasound: Thoracic Exam Purpose: evaluate for etiology of respiratory failure- pleural fluid collections, pneumothorax, infiltrate, pulmonary edema. Probe Linear for visualization of superficial structures- for example, the pleural interface to evaluate for lung sliding Curvilinear or phased array for the remainder of the lung Findings A and B Lines A-lines- *normal finding*. Hyperechoic arcs parallel to the pleural line. These are seen at intervals that are the same as the interval from the skin to the pleural line. Absence of A lines= change in attenuation coefficient of the lung (edema, consolidation). B-lines- vertical hyperechoic lines, caused by fluid-filled intra-lobular or interlobular septa touching the visceral pleural surface. Examples: cardiogenic pulm edema, ALI, ARDS, pneumonia, ILD or pulm fibrosis, pulm contusion. Comet tail artifact- *normal finding*. Arise from the pleural line and only extend 2-4 cm deep before fading (unlike B lines). They mean that the pleura are in contact. Pleural sliding Shimmering of the hyperechoic pleura→ pleura are in contact. No sliding→ concerning for PTX. There are clinical conditions other than PTX that result in a lack of lung sliding: Effusion, inflammatory adhesions, (pneumonia, ALI), pleurodesis, interstitial or fibrotic lung disease, pleural disease, apnea, severe hyperinflation (asthma, COPD), artifact (subQ air). M mode- sliding→ seashore. No sliding→ barcode. Lung pulse - cardiac motion causes the two pleura to slide Lung point - the junction between the edge of the pneumothorax and the normal lung, where the pleural surfaces meet. One side is sliding and the other side isn’t. Consolidation Air bronchograms- air in small aerated patches of the consolidated lung, or the small bronchi. Dynamic- bubbles move in and out with each breath- no complete bronchial obstruction, more likely true consolidation vs atelectasis. Pneumonia- advanced consolidation (air is completely replaced with fluid)→ lung appear to have a liver-like echogenicity (hepatization) Diaphragm - evaluate diaphragm contraction and thickness. Effusions Spine sign- the presence of a large effusion allowing visualization of the spine. Normally the air in the lung prevents visualization of the spine above the level of the diaphragm, but sound waves can pass through the fluid. Plankton sign- floating debris in an effusion that swirl with pulm or cardiac motion→ blood/ fibrin suggestive of HTX/ exudate Jellyfish sign- consolidated or compressed lung is floating in the pleural fluid. Common Pathologies with their associated ultrasound findings PTX- no lung sliding, M-mode barcode sign, lung point sign, A-lines from intact parietal pleura Pulmonary edema- B lines, normal lung sliding, +/- effusions ARDS- B lines, normal lung sliding References Lung Ultrasound Made Easy: Step-By-Step Guide Lee FC. Lung ultrasound-a primary survey of the acutely dyspneic patient. J Intensive Care. 2016 Aug 31;4(1):57. Previous Next

< Back Vent Mgmt #5: Weaning When is the patient ready to start ventilator weaning? Resolution of pathology resulting in the need for mechanical ventilation Able to assess mental status (ie can the patient follow commands) Hemodynamics and respiratory physiology is optimized (ie ABG normalized or returned to patients baseline, and normalization or stabilization of cardiac function) Minimal ventilator settings (FiO2 21%, PEEP 5) NOTE: Even if there is no immediate plan to extubate, sedation holiday and spontaneous breathing trials should still be performed [unless there are specific contraindications] Spontaneous breathing trial Spontaneous mode of ventilation (such as pressure support or CPAP) with 5-8 cm H2O support during inspiration (basically overcoming the force required to breath through the small diameter of the ETT) Failing SBT Hemodynamic instability (hypotension or hypertension, tachycardia or bradycardia) Agitation Respiratory instability (hypoxia, inadequate tidal volume, tachypnea or decreased respiratory rate) Extubation parameters- how do we know if the patient is ready to be liberated from the ventilator? Able to generate adequate minute ventilation Rapid shallow breathing index (RSBI)- RR/ TV. High respiratory rate (rapid) and low tidal volume (shallow) are more suggestive that a patient isn't appropriate for extubation. Value <105 suggests the patient will successfully extubate. This is also known as the Tobin index.[1] Negative inspiratory force (NIF)- the patient's ability to generate negative pressure with inhalation. Cuff leak- ability to move air around the endotracheal tube. Not mandatory to evaluate for cuff leak prior to extubate EXCEPT for patients is at high risk for airway edema (traumatic intubation, intubated >6 days, large ETT, female, reintubation after unplanned extubation). Reasons for failed ventilator weaning Prolonged hospitalization and associated weakness Hypophosphatemia Primary process requiring mechanical ventilation is unresolved Passed SBT...but failed ventilator liberation? Excess secretions/ inability to cough Cardiac instability related to physiological changes with loss of positive pressure (specifically decrease in intra-thoracic pressure leading to decreased cardiac output) Tobin Index. Yang KL, Tobin MJ. A Prospective Study of Indexes Predicting the Outcome of Trials of Weaning from Mechanical Ventilation. N Engl J Med. 1991 May 23;324(21):1445-50. Previous Next

How to be a Terrible First Date Dating, Pt 2 How to be a Terrible First Date Recently, I was set up on a blind date. He seemed like a normal mature guy via text. Polite, intelligent responses, etc. We agreed to meet at a local bakery. My first clue should have been the fact that he didn't have the fortitude to message me first. I don't do a great job of taking my own advice…I had told myself I wouldn't message first, that he would have to be the guy and reach out first. Oops. When I showed up, he was sitting outside. I sat down and he asked if I wanted to order something. He told me they have great food and good coffee, to which I replied that I don't drink coffee. And the date careened downhill from there. His response? Not drinking coffee is a red flag that a woman isn't a good partner. Goes along with not liking chocolate. He declared that if something else goes wrong later in the relationship, you can look back and say yeah they told me there was something wrong from the beginning. Then he went off on a tangent about how people who don't eat the same kind of foods won't be compatible in relationships. For example a vegetarian and a vegan. More specifically, a really douchey vegetarian or vegan. I didn't know people still used that word…actually, I didn't know that it was ever used out loud as an adjective by a guy. He continued with other crazy comparisons. Like Jewish people who don't eat pork. Or cannibals. Or carnivores. Told me a story about having a friend who ate dogs. Some context for the dog-eating conversation-- there was an adorable medium-sized fluffy black and white dog sitting about 3 feet away from us. He and his owner are clearly within earshot. He continued…."do you see that dog right there, she (his friend from Asia) would think it would be OK to eat a dog." I didn't know what to say to that. All I could say at that point was that I could never eat that dog, that I couldn't even kill a dog! His monologue about eating continued with an explanation of why humans are the superior beings on the planet. The bottom line was that the thing that makes us the superior being is the fact that we can eat any other animal. It's not our intelligence (dolphins are more intelligent), it's not our technology, we aren't faster or braver. But we can eat any animal. And somehow he related this to the use of smartphones- using a smartphone doesn't make you smart. A stupid person can use a smartphone but still eat any animal. He then delved further into the world of food and eating with a rant about McDonald's. You’ve heard of McDonald's, right? Are you too good to eat at McDonald's? Have you heard of Jim Gaffigan? He does a skit about McDonald's. You ever run into someone at a McDonalds’s and they ask what you’re doing there...you just pretend you’re meeting a hooker. Him: McDonald’s fries are the best thing. Me: not if they’re cold. Him: Well you have to eat them within 5 minutes. After those five minutes, they’re no longer food. Me: But they aren’t always warm when you get them. Him: Then that’s your fault. If you don’t check and you drive away, it’s on you. You can’t blame anyone else. Me: But who wants to be the person who holds up the line in the drive-thru? Him: You have to be coordinated, pay, and inspect the fries all at the same time. And if they’re cold, you hand them back and say these are cold I need new fries. And everyone in that line behind you will understand that. If you drive away and the fries are cold, it's your fault. I tried to change the subject by commenting on the restaurant. Told him there was a place I previously lived that had similar food, but the décor on the inside was quirky. It was awesome because it was open 24/7. His response…there weren't other places open 24/7? IHOP? I asserted that there were not many places….maybe Huddle House. He said he's never been to a Huddle House. I said it's like a worse version of Waffle House. He said, have you ever been to a Waffle House? It's like a truck stop bathroom with a kitchen. I told him, yes, and that Huddle House must be an East Coast thing. He told me they don't have it up north, so I said Ok, maybe it’s a North Carolina thing. Why does everything have to be a disagreement??? Finally, after complaining about not wanting to give up the table he picked, he agreed that we should go in and order food. When we were in line to order, the conversation took on a slightly different tone. He proceeds to lecture me on the fact that making requests or asking questions regarding food at a restaurant is a personality flaw. He also told me that you need to try everything at least twice. Without even knowing me, he was insulting people who make requests at a restaurant. He made some mention of bacon, and I said I don't care for bacon, and asked whether not liking bacon is as bad as not liking coffee or chocolate? He said that's not a big deal in Texas, maybe in North Carolina or Georgia it would be (the last two places I've lived…again, he knows nothing about me). When I asked why I have to try something else two more times when I already know what I like (or don't like), he said, what if you get to be 80 years old, and your tastes have changed? He told me, just go with the flow….he said if he orders beans and they give him rice instead, he'll just eat the rice. Me: But what if you really want beans. Him: Just go with it, order the beans next time. Some people eat dirt and mud. Me: Just because there are people who have to eat dirt doesn't mean we just have to eat whatever is given to us. Him: Don't ask a lot of questions to someone who barely has a high school education. So basically…he doesn't have a spine to ask for what he wants when he eats out. Probably translates into other areas of his life where he isn't able to stand up for himself…just a guess. So now that he's already insulting people who have preferences about food, I had to tell him about a recent outing with work colleagues. We went to an outdoor American food place, and I wanted a plain burger. The only thing they had on the menu was a burger with brisket on top. So I asked my friends if that meant brisket sauce or actual brisket meat. Immediately, my date tells me I asked too many questions. I tried to play along, acquiescing that barbeque is a big deal in Texas. But then, I said I don't eat that much food at one time and I didn't want more meat on my burger. He told me not to complain, and just eat half and give it to a homeless person. He told a story about giving food to a homeless person once in Austin…the homeless person asked if it was gluten-free, and then when he said I'm not sure, and the homeless person said, ok, never mind. So a weird humble brag, talking bad about a homeless person while simultaneously telling me he is a generous person. So again, it was my turn to tell a story about myself to see how he'd insult me some more. Me: I went to a restaurant that I really liked back home and I like the green beans there. I went there one time and they didn't have green beans. Him: You can be sad about that but don't be whiny about it. The restaurant was relatively crowded, kinda looked more like a Saturday morning than a Thursday morning. He did that awkward thing where he says rude things out loud so everyone around us can hear him being insulting. Him: Why are there so many people here? It's a Thursday morning. These people should be at their jobs. Me: You do realize we are here, right? The menu advertised a breakfast sandwich…which I guess I was going to order but had to make sure not to ask questions or tell them what I want. In an attempt to make a sarcastic joke, he asked about whether the sandwich was gluten-free. And if the chickens were free-range. I made a joke and asked if the chickens were treated well and whether they were mocked as children. When we got back outside, he complains about the fact that the table he had been sitting at was taken. Then he walks around and complains that the rest of the tables are equally bad. Not so easy going now, eh?? We sat outside, and as we were waiting for our food, several birds were dive-bombing me, to which I responded like a normal person and ducked. He proceeded to chastise me for not standing up to the bird and not asserting my dominance. He told me it didn't bode well for my offspring that I couldn't stand up to a bird. Stated I would just let my children be pecked to death by birds. Said I'd be helpless, and hopeless for the rest of my life. Literally used those words. Not even implied, straight out said I was hopeless and helpless. Somehow we got on the conversation of working, basically said he only does his job to make money. I asked him if he enjoyed it or enjoyed helping people, and he said being a neurologist was the best he could come up with using the advantages he was born with. He said there was nothing better he could do to make money, to which I replied that he was choosing to limit himself. While we waited, he decided to give me a lesson on animals and nature. On nature shows, the lion is shown as the majestic king of the jungle, but they hide the fact that lions will eat their young. This part was much funnier in person because his tone of voice and storyline was so ridiculous. Like he was actually offended or thought it was a conspiracy that this wasn't shown on TV. He also gave a long monologue about how big birds eat other birds. Like helpless penguins. Birds try to eat their eggs. Sometimes the big bird will be looking down and the other bird knows it's about to get eaten. Other times, the other bird doesn't even know. It'll just be sitting there one moment, and the next moment, hey I'm being eaten. When I turned and spoke to one of the many dive-bombing birds, he proceeded to correct me about calling a bird the wrong gender. He stated that men are the brighter of the bird species because they have to attract the female bird. Told me about watching a show that talked about males of different species trying to attract females. Like fish get the rocks all together to show the girl fish that they can make a nice place, and then the girl fish comes over, so the male fish does a dance, and then if they get turned down by a female, they clean up the rocks and try again. Birds try to make the best nest to impress female birds. Then he told me that males are brighter than females, across all species. To which I disagreed, stating that I don't think men are more colorful than women. He corrected me, saying that’s why men wear ties…. Again, I told him I'm pretty sure females are more colorful. And he said, yea, women just like to shop. He also told me he could tell which was a female bird because they were the ones that ate everything. Yes, he said those words. Out loud. To a woman he'd never met. Throughout the date, he spent 97% of the date not talking about me or asking about me. I did proceed to tell him about the time I was attacked by dogs. And I told him it changed my life. He responded by asking (at least twice) what I did to the dogs to make them attack me. Seriously. Told him my story about the dogs. After I finished, he asked if I was bleeding. I recounted my story of going to the ER…to which he responded with…nothing. No sympathy. No nothing. Told him the rabies shot is really painful because they had to put it in my ankle. He said they probably did it wrong and it was his goal in life to never need a rabies shot. I then told him about how it changed the nature of my deployment…again, no questions about me. I told him it was odd to talk about birds eating each other on a first date. And I didn't know how he planned to get second dates after that conversation. He said he had watched a documentary with his niece and it was something he learned. Then he asked me what I learned. And then just stopped talking and went back to eating. Didn't even eat half my breakfast…so uncomfortable, and I wondered if he would tease me for eating all my food. By the way, he also sat with his feet on the chair next to me, legs straight. Back when we were in line ordering breakfast, I asked if he was cold, cause he had long pants, a sweater, and a long black wool coat. He said, no, he wore that so he wasn't cold… During breakfast, he told me because I had my arms folded that I was either cold or standoffish. Said that a few times over and over to me…and he even mocked me by folding his arms tightly across his chest and scowling. I then laid my hands on the table in front of me. He continued to mock me. Later, he noticed goosebumps and told me I was cold. And then told me because I wasn't furry (or hairy, I don't remember), goosebumps mean I'm cold. Later on, we took a walk along the river walk. It was mostly painfully awkward silence. But a few times, he did that weird thing talking out loud saying awkward things that other people can hear… There was a lady behind us with a stroller. He said, "I feel like we're being followed". Later, a yappy little dog barked at us, to which he said "no kill, no kill". The only interesting thing he talked about was racing cars. He mostly mumbled quietly, but I encouraged him to speak up and finally learned something interesting about him. He races cars- most recently a Ferrari, and he just bought a Lotus that he is getting ready for racing. He also used to race a Honda Accord. Reminds me of an ex-boyfriend who drove a Ford Taurus, but was convinced that just because he could hit the gas pedal hard, he was a race car driver… And then, just like that, mercifully, the torture was over. He walked us back to his car, pointed it out, and then walked away. Didn't ask where I parked or offer to walk me back. Again, all the little things can be written off as one-offs. Ok, fine, he didn't walk me to my car. Fine, he put his feet on the chair next to me. Yadda yadda yadda. But all together within like an hour? Come Previous Next

Surgery trainee education. Trauma surgeon. Acute Care Surgery. Collaboration Interested in being a guest contributor? Any suggestions and contributions will be promptly reviewed and added to the appropriate page/ subpage. The contributor will be noted on the website- you can choose if you want your name or Twitter handle or whatever other identification you would like (or none at all if you would like to be anonymous). Content currently under development. Note- this list is NOT all-inclusive. Database of clinical vignettes in key topics of trauma, critical care and emergency general surgery. Focused on more complex scenarios (ie not run-of-the-mill appendicitis)! Please check out the vignettes I currently have to get an idea of what I’m trying to create- and reach out with any suggestions or cases. Literature reviews - deep dives, high-yield articles, etc Procedural or skill tutorials (pre-peritoneal packing, using the ultrasound in critical care, reading a chest x-ray). Each tutorial is followed by a list of primary sources, encouraging readers to pull information from multiple references. If there is any particular procedure or skill that you would like to create a tutorial for, or something that is currently on the website that you would like to enhance (for example, more advanced ultrasound techniques or ventilator settings), please feel free to reach out with suggestions! There is a wide array of other content that you can add to as well. Note templates Recommendations on networking opportunities Recommendations on social media accounts to follow Educational resources (textbooks, journal articles, training courses, web based open access medical education) Please send me an email (form at the bottom of the page) or contact me on Twitter @doc_on_the_run if you have any questions or want to submit something.

< Back Ultrasound: Misc Abdomen Assess for intra-abdominal fluid to rule-out an intra-abdominal source of hypotension. Examine the gallbladder- gallstones, wall thickening (>3 mm) and pericholecystic fluid are consistent with cholecystitis Examine the kidneys and bladder- overt hydronephrosis concerning for mechanical obstruction. Distended bladder despite foley suggests obstructed foley. Vascular Presence of DVT- patent veins are fully collapsible with light ultrasound compression- pressure has to be lower than the pressure needed to collapse the artery. Vascular access for arterial and central line placement. Previous Next

About Doc on the Run About Doc on the Run Active Duty Army Acute Care Surgeon. Nomad. Runner. Music aficionado. Culinary amateur. Intermediate-level technology nerd. Christian. Inquisitive life-long learner. My primary passion is surgery, and my life has been dedicated to becoming a trauma surgeon. After graduating high school at 17, I attended the University of Missouri, Kansas City, a six-year medical school. I was commissioned in the Army and completed 6 years of General Surgery residency in Augusta, Georgia. Board-certified in General Surgery. For 3 years, I was a staff General Surgeon in North Carolina and deployed to Iraq, Kuwait, Jordan, and Africa. Board-certified in Surgical Critical Care and completed a two-year AAST Acute Care Surgery fellowship in North Carolina. I spent two years in San Antonio, Texas, and then 1 year in South Korea, where I finished out my career on Active Duty. Photo courtesy of JW, 2013

< Back Vent Mgmt #3: Pressures Inspiratory Pressures Pressure Controlled Ventilation (PCV) End-inspiratory pressure= alveolar pressure. The pressure is essentially constant during PCV- high flow at the beginning to get to target pressure, then flow tapers until it ends (no airflow at end inspiration). Can't measure resistance because flow rate is dynamic. Volume Controlled Ventilation (VCV) Peak inspiratory pressure (PIP)- maximal pressure with inspiration. Sum of plateau pressure and pressure required to overcome airway resistance. Keep <40 cm H2O, SCCM recommends below 30 for ARDS. Abnormalities: elevated PIP indicates high resistance (secretions, bronchospasm, biting tube). Plateau pressure= alveolar pressure. Mean pressure during end-inspiratory pause, basically when there is no air movement. Not affected by resistance. Goal ≤30 cm H2O. Abnormalities: elevated plateau pressure indicates poor compliance. Driving pressure= plateau - PEEP. Goal ≤15 cm H2O (>15 is associated with ↑mortality). PEEP can either improve or worsen driving pressure. If the set PEEP promotes recruitment→ ↓driving pressure. If the set PEEP creates overdistension of the alveoli→ ↑driving pressure. End Expiratory Pressure Positive end expiratory pressure (PEEP)- lowest pressure that avoids alveolar collapse, which occurs when intrapleural pressure is higher than intra-alveolar pressure. This is indicated by the lower bend on the pressure/ volume curve, known as the lower inflection point. Mean Airway Pressure Mean airway pressure (MAP)- average pressure the lungs are exposed to during the breathing cycle. One of the two parameters that determine oxygenation. - How to increase MAP: ↑PEEP. If using IRV, ↑inspiratory time (Thigh) and ↑inspiratory pressure (Phigh). Parameters that Impact Airway Pressures Resistance- change in pressure relative to flow (PIP - plateau/ peak inspiratory flow). Relationship between PIP and plateau is directly related to airway resistance. ↑PIP and [PIP - plateau >5 cmH2O]= ↑resistance (bronchospasm, ETT obstruction/ kink). ↑PIP and ↑plateau [PIP - plateau <5 cmH2O]= ↓compliance (PTX, ARDS, pneumonia, edema, auto-PEEP). Compliance- change in volume per change in pressure. Normal- 50-100 mL/ cm H2O Previous Next

< Back Ultrasound: Just The Basics Ultrasound is a non-invasive, repeatable, portable, reproducible diagnostic tool. It can be used virtually anywhere that patient care is being performed, including pre-hospital, the ER, OR, ICU, and non-ICU inpatient wards. Ultrasound skills vary between providers. I am a strong advocate of utilizing the ultrasound, and you will become more comfortable as you increase your utilization of the US. The credentialing process for ACS surgeons is not well-established, and we do not have the same expertise as radiologists. SCCM guidelines currently support ICU providers' utilization of US for certain scenarios. However, ICU providers are not as reliable in certain diagnoses, such as biliary pathology. Basics of Ultrasound: How Does it Work? Crystal excited by electrical pulses (piezoelectric effect)→ mechanical oscillations→ sound waves emitted. Sound waves are reflected at interfaces of different acoustic densities. Higher acoustic density→ increased intensity of reflected sound and decreased transmission of remaining sound waves. If the interface is between objects of vastly different acoustic density→ complete sound wave reflects and total acoustic shadowing occurs (dark behind the object); examples include bone, stones, and air. Probe selection Linear array- parallel sound waves→ rectangular images. Near-field resolution, high frequencies 5-7.5 MHz)- good for thyroid and soft tissue. Artifact on curved surfaces. Not good for intra-thoracic or upper abdominal organs. Sector/ phased array- fan-like image (narrow nearest transducer and widening with deeper penetration). Frequency 2-3 MHz. Poor for near-field resolution. Used for cardiac imaging. Curved (convex) array- abdominal sonography. 3.5-3.75 MHz. Deeper tissue penetration. *Probe marker correlates with the dot on the screen to establish orientation. Artifacts Reverberation echoes-several strongly reflecting boundaries→ reflection of sound waves back and forth→ echoes (several parallel lines close to the transducer). A-lines when scanning the lung- hyperechoic arcs parallel to the pleural line. These are seen at intervals that are the same as the interval from the skin to the pleural line. Absence of A lines= change in attenuation coefficient of the lung (edema, consolidation). B-lines when scanning the lung (comet-tail artifact)- vertical hyperechoic lines, caused by fluid-filled intra-lobular or interlobular septa touching the visceral pleural surface. Distal acoustic enhancement- sound waves travel through homogenous fluid (low reflection)→ less sound wave attenuation, so they are more amplified compared to adjacent sound waves (because the structures they passed through reflected some of the waves). *Brightness (increased echogenicity) behind fluid-filled structures such as the bladder or gallbladder. Mirror image- diaphragm and visceral pleura→ intrahepatic structures can be seen on the pulmonary side of the diaphragm. Acoustic shadowing- interface between tissue and bone or tissue and air→ scattered beam→ inability to image deeper structures. Knobology Identify the probe Identify the selected study type (cardiac, FAST, soft tissue, etc) Gain- increases the strength of sound/ brightness of the visualized area Depth-gain compensation- selective enhancement of echoes received at different depths→ moving depth up or down increases or decreased the field of view. Time-gain compensation- adjust the strength of the beam to areas that would normally have attenuated beams. M-mode- display and measure movement of structures over time along a single lione (axis of the beam). Good for heart or valve motion (echo), hemodynamic status (respiratory change in IVC diameter) and lung sliding or diaphragm movement. Doppler- changes in frequency cause by reflections off a moving target (usually blood). References Frankel HL et al. Guidelines for the Appropriate Use of Bedside General and Cardiac Ultrasonography in the Evaluation of Critically Ill Patients-Part I: General Ultrasonography. Crit Care Med. 2015 Nov;43(11):2479-502. Levitov A et al. Guidelines for the Appropriate Use of Bedside General and Cardiac Ultrasonography in the Evaluation of Critically Ill Patients-Part II: Cardiac Ultrasonography. Crit Care Med. 2016 Jun;44(6):1206-27. Labovitz AJ et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American Society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr. 2010 Dec;23(12):1225-30. Borloz MP et al. Emergency department focused bedside echocardiography in massive pulmonary embolism. J Emerg Med. 2011 Dec;41(6):658-60. Bakhru RN, Schweickert WD. Intensive care ultrasound: I. Physics, equipment, and image quality. Ann Am Thorac Soc. 2013 Oct;10(5):540-8. Silverberg MJ et al. Intensive care ultrasound: II. Central vascular access and venous diagnostic ultrasound. Ann Am Thorac Soc. 2013 Oct;10(5):549-56. Doerschug KC et al. Intensive care ultrasound: III. Lung and pleural ultrasound for the intensivist. Ann Am Thorac Soc. 2013 Dec;10(6):708-12. Boniface KS et al. Intensive care ultrasound: IV. Abdominal ultrasound in critical care. Ann Am Thorac Soc. 2013 Dec;10(6):713-24. Repessé X et al. Intensive care ultrasound: V. Goal-directed echocardiography. Ann Am Thorac Soc. 2014 Jan;11(1):122-8. De Backer D et al. Intensive care ultrasound: VI. Fluid responsiveness and shock assessment. Ann Am Thorac Soc. 2014 Jan;11(1):129-36 Labovitz AJ et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American Society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr. 2010 Dec;23(12):1225-30. Borloz MP et al. Emergency department focused bedside echocardiography in massive pulmonary embolism. J Emerg Med. 2011 Dec;41(6):658-60 . Emergency Ultrasound Tutorials American College of Emergency Physicians: Ultrasound Lectures Previous Next

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