Critical Care Scenarios

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Dr. André Mansoor (@AndreMansoor), associate professor of medicine in Portland, Oregon, author of the excellent Frameworks for Internal Medicine, and contributor to Physical Diagnosis PDX, talks us through a complex case of encephalopathy and respiratory failure to illustrate some principles of diagnostic reasoning.

Takeaway lessons

1. The hardest part of treating most diseases is making the diagnosis. Countless resources are available to assist with treatment pathways, but you won’t know which one to use if you don’t know what you’re treating. Empiric treatment is sometimes necessary in the critically ill, but it tends to obfuscate, not support diagnosis.
2. Even diagnostic support tools (such as burgeoning field of artificial intelligence) will require clinicians to collect the contributory data points, such as history and physical exam findings; this still requires enough diagnostic acumen to guide the data-gathering process.
3. The H&P is not “over” after the initial survey; an iterative back-and-forth process ensues between discovering diagnostic abnormalities and using them to formulate new hypotheses that direct additional, more focused questions and examination.
4. Most hypoxemia is best approached by first calculating, or at least approximating, the A-a gradient. This routes you into completely different diagnostic pathways depending on the results.
5. Guillain-Barré is best confirmed by lumbar puncture showing an elevated protein without pleocytosis. However, start with a physical exam suggestive of lower motor neuron disease.
6. Start with a general history and exam, but after that, broad or “shotgun” testing, consultation, or empiric therapy is high in cost and complications, and just doesn’t tend to work. Formulate specific hypotheses and use your studies or consultations to test them.
7. 90% of diagnoses are made from the history and physical alone. Lean on these as the cornerstone of your diagnostic process, not on high-tech tests.
8. It’s reasonable to treat a patient who easily matches a standard disease script as if they have the common disease. But when they have features that appear a little different, that’s a good time to step back and work your diagnostic process methodically.

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An overview of VV ECMO with a focus on COVID-19, with Dr. Kimberly A. Boswell (EM and CCM) of the University of Maryland, perhaps the busiest center in the country for COVID-related ECMO. We discuss evaluating for candidacy, induction, maintenance, weaning, and general approaches to the COVID patient.

Takeaway lessons

1. The limited amount of ECMO resources has led to narrowing of criteria. Maryland has reduced their standard upper age limit from <65 to <55, BMI of <40, mechanical ventilation duration <7 days (formerly <10). Also consider other organ failures, as well as duration of symptoms—not just intubation—as a prolonged pre-intubation course suggests a late, potentially fibroproliferative phase of disease which may not be responsive to ECMO.
2. Almost all COVID cases at Maryland have been VV ECMO; they have very rarely considered VA ECMO. The most obvious indication for the latter would be right heart failure, but in most cases, they would be more likely to use VV ECMO (or other medical therapies, such as inhaled vasodilators or diuresis) to unload the right heart, or else to consider severe cardiogenic shock to actually be a contraindication to ECMO (as it suggests a late stage of disease less likely to respond to aggressive care).
3. There is no obvious timeframe which is “too early,” but patients already
   at ECMO-ready centers might reasonably wait longer to go on bypass, as it can be done quickly and safely when necessary without requiring interfacility transport.
4. Cannulation can be done by whomever is skilled and trained, such as cardiac surgery, trauma surgery, trained intensivists, etc.
5. For VV ECMO, Maryland likes to cannulate the right IJ and right femoral veins, or perhaps the left femoral if needed. They prefer not to cannulate bilateral femorals, and prefers not to use dual-lumen IJ catheters (the Avalon bi-caval catheter), as flow is often not adequate.
6. Anticoagulate most patients on VV ECMO with heparin to a PTT of 45-55. VA ECMO can go to 60-80. ECMO without anticoagulation can be done if there are bleeding issues, however.
7. Maryland generally does not titrate FiO2 on the sweep gas. After induction, titrate the sweep; the goal is usually to correct hypercarbia over 6–8 hours, not all at once.
8. Flow rates at least 4 L/min, unless more is required for hypoxia. RPM <4000 is usually the starting goal.
9. Prone even while on pump for lung-protective reasons. Chest PT is good too. Prone first for 6-8 hours to ensure tolerance and skin integrity, then do around 4 more sessions of 16 hours each, as a starting goal.
10. Ventilator settings on VV ECMO can be walked back after induction. Historically they used PEEP 10, PIP 10, RR 10. In heavily consolidated COVID patients, some need more pressure to maintain some degree of recruitment, such as PEEP 15 and PIP 10.
11. Inhaled vasodilators can be continued or weaned depending on right heart function. Diurese until you develop flow problems (suction events) on the pump, a useful indicator of low intravascular volume.
12. Have a low threshold to deeply sedate and/or paralyze while on pump to optimize synchrony and facilitate proning. However, Maryland likes to perform “partial paralysis,” with just enough NMB to achieve goals; respiratory rates below 20 or so are considered acceptable.
13. Early tracheostomy is reasonable, but persistently high requirements for ventilator pressures often pushes it back.
14. Hypoxemia can occur in VV ECMO patients due to too much flow through the native circulation and shunted lungs. In such cases, beta blockade may actually improve systemic oxygenation.
15. Plasma free hemoglobin levels may be a useful marker that changing your oxygenator could improve gas exchange.
16. Decannulate at the bedside when ready, watch them for 24 hours, then boot them out of the ICU; they’re ready.
17. 65%+ of COVID ECMO patients at Maryland are surviving. Data remains slim, but there seems to be decent results in a well-selected population.
18. In rare cases, patients who neither die nor recover may become candidates for lung transplant.

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Back with returning guest Dr. Elliot Tapper (@ebtapper), gastroenterologist, transplant hepatologist, and director of the cirrhosis program at the University of Michigan in Ann Arbor, to talk about critical GI bleeding.

Takeaway lessons

1. Consider the Glasgow-Blatchford score to stratify risk and need for admission, GI consultation, etc.
2. Octreotide (or terlipressin) is indicated in every cirrhotic with GI bleeding, i.e. patients with confirmed or probable varices.
3. Proton pump inhibitors are appropriate for bleeding ulcers. Note they are not needed in variceal bleeding, and are not needed if octreotide is also being given; octreotide reduces gastric pH just as much as a PPI.
4. Bleeding cirrhotics should receive antibiotics. They have a high risk for inpatient infections, whether from bacterial translocation, instrumentation, etc.
5. By and large, twice-daily PPIs are as good as PPI drips. The latter is mostly an evidence-free Hail Mary addition.
6. As a general rule, colonoscopy for lower GI bleeding rarely needs to be done urgently; at most, early colonoscopy (within 24-48 hours) may reduce length of stay, but the yield of finding intervenable findings (particularly in unprepped bowel) is extremely low.
7. In very unstable patients, it is not very common that you would need to place a gastric tube and perform lavage to prove an upper GI bleeding source; just do the EGD. In less obvious cases it can be quite useful, though. Don’t be misled by trace amounts of bleeding, which can occur (due to stress) even in lower GI bleeds.
8. NG/OG placement in the setting of varices is safe, unless there’s been recent banding performed.
9. Early CTA is a good approach for severe lower GI bleeding. It is basically never the first line approach for presumed upper GI sources, however; IR embolization is less effective here (due to the redundant blood supplies), and endoscopy will help localize the bleeding source for any needed embolization anyway.
10. “Early” EGD usually means within 12 hours and is appropriate for active bleeds that are not catastrophic.
11. Although massive bleeding can result from varices, with good medical treatment it is actually rare. In most cases judicious transfusion can be used to avoid overly increasing venous pressures.
12. For truly rapid upper GI bleeds, intubate early (to prevent aspiration and facilitate EGD), ensure adequate IV access, and perform emergent EGD; endoscopy remains the first line treatment. Even when visualization is difficult it provides useful information by localizing the bleeding region. Normal (Hgb >7) transfusion targets are not relevant in active exsanguination. A PPI drip is reasonable but is not particularly high yield at this point.
13. Balloon tamponade (Minnesota or Blakemore tubes) has its own risks, and few clinicians are expert at their placement. Overall it is rarely needed unless endoscopy is not immediately available, such as if a patient needs transfer to another institution.
14. EGD can lead to rescue surgery if it visualizes bowel perforation, and to IR if a bleeding vessel is found that can’t be addressed endoscopically.
15. Repeat endoscopy during the same hospitalization is rarely needed. For ulcers, it is common to re-scope in about 8 weeks to make sure it has healed and is not cancerous.

References

The Glasgow-Blatchford Bleeding Score (GBS) to stratify risk.

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Back again with Dr. Ross Hofmeyr (@rosshofmeyr), anesthesiologist in the Department of Anaesthesia and Perioperative Medicine at the University of Cape Town, to discuss an expert’s perspective on airway management in the COVID-19 patient.

Takeaway lessons

1. Good practices for intubating COVID patients are, by and large, good practices for intubating anybody. Using a standardized protocol, appropriate PPE, applying best practices to optimize success, and pre-assigning roles has no downside.
2. Support each other by using “call/response” checklists and buddy checking PPE.
3. Ross’s protocol: one attempt at intubation, immediate placement of supraglottic airway if it fails, then proceed to another attempt. First line with video laryngoscopy using a Macintosh blade. No mask ventilation (to limit aerosolization) except as third line if SGA fails. Mask with two hands, two operators, and a PEEP valve.
4. Patients need oxygenation, and to a much lesser extent ventilation, but not tubes per se. Whatever method achieves that in an emergency is okay.
5. You need PEEP to preoxygenate the hypoxic COVID patient. High flow nasal cannula is okay, but a BVM with PEEP valve provides real PEEP and usually improves preoxygenation. HFNC with a mask on top is less clear as the large cannula can cause air leak.
6. Learning to bag-mask ventilate on mannequins teaches bad habits. Learning in the OR with real humans and an anesthesia bag is a better place.
7. Intubate everyone with head of bed elevated PLUS head in a sniffing position. Blankets are better than pillows. Start with more elevation than you need; it’s easier to remove than to insert.
8. Move the bed. True 360 degree access to the bed makes a difference.
9. Proper preparation makes most of the difference to success. Even experienced anesthesiologists have dramatically reduced first-pass success when removed from their usual OR setting, likely due to less preparation.
10. By and large, different types of PPE should not affect intubation success if the team is highly-skilled.
11. Ross’s team favors induction with fentanyl, etomidate, and succinylcholine (unless hyperkalemic, then rocuronium). The small advantage in speed with sux is worth it in these rapidly-deoxygenating patients.
12. Use a verbal call/response checklist to make sure nothing has been missed, slow down the pace, and create a shared mental model among the team (particularly if not everyone is part of the usual group). This only takes a significant amount of time if you actually find deficiencies that need correcting (in which case you’ll be glad you took it), and it adds value almost every time.
13. Many patients will be dehydrated and hypovolemic at the time of intubation, particularly if they’ve been on non-invasive for some time (often not eating/drinking) and most of all if they’ve been on non-humidified oxygen, such as regular cannula and/or masks.

References

SASA (South African Society of Anaesthesiologists) COVID-19 protocol and recommendations

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Back in the arena with one of our favorites, Matt Siuba (@msiuba), Cleveland Clinic intensivist and Mr. Zentensivism, to discuss complications in critical care and how to prevent and manage them. Today we focus on atrial fibrillation with RVR and bleeding after thoracentesis and related other procedures.

Takeaway lessons

1. Rapid atrial fibrillation in the ICU should be considered a “symptom,” not a disease per se. Look for stressors or triggers for tachycardia, such as infection, agitation, etc. Resume home agents if they exist — or don’t hold them to begin with — especially beta blockers, as rebound can occur with discontinuation. Don’t get too hung up about converting the rhythm. Give magnesium early and often, acknowledging that rapid administration tends to provoke rapid loss to the urine and you may be better served to stretch it out.
2. A-fib with a rate below the 130s-140s is unlikely to be the cause (rather than an effect) of shock, outside of structurally abnormal hearts that need filling time or atrial kick (such as diastolic failure).
3. Remember that you have time to address rapid A-fib in a stable, minimally symptomatic patient, regardless of the rate. You can only make them less stable. Go slow and be thoughtful.
4. Good reasons to perform therapeutic thoracentesis include work of breathing. Less common reasons include hypoxemia. If you suspect you may need to re-tap, consider leaving in a drain.
5. Under ultrasound, put color doppler on the thoracic wall to confirm there are no unexpected vessels at your puncture site; do this in two planes and use a superficial probe.
6. You do not need to use real-time ultrasound guidance for the thoracentesis puncture unless the pocket is quite small; you can always ultrasound the wire after it’s in place if the wire entry felt weird. It takes some practice to maintain a good relationship to the rib while also guiding yourself under ultrasound.
7. Anchor your needle hand to the patient so unexpected movement will not shift your position, and use the smallest needle necessary. Consider performing smaller thoracenteses with a micropuncture kit rather than with a larger catheter like a pigtail; insert the micropuncture sheath and use it to drain the fluid. Small needle, small catheter, safe.
8. A “dry tap” with your thora needle should prompt a different technique, not repetitions of the same one. Change something or check your position to ensure you’re not below the diaphragm. After one or two attempts, consider handing over to someone more experienced.
9. Finding blood in your pleural tap should make you pause, but not panic. Traditionally you can send it for a hematocrit, but this is rarely very useful. Generally you can complete the tap and see if it clears. Afterwards, reinvestigate the space under ultrasound to ensure no blood is reaccumulating, and monitor the patient closely; occasionally they may need a CTA and embolization. Consider leaving a drain to monitor output, although be sure to flush it regularly to prevent clotting. Investigate for other reasons there may be hemothorax, such as trauma, previous taps, or malignant exudates.
10. If you suture a line or other device and it won’t stop bleeding, you may have caught a superficial vessel (e.g. the EJ when performing an IJ). Take those sutures out or it’ll never stop.
11. Complications happen. They should generally prompt introspection to consider whether practice should be changed: could I have been better prepared to do that? Was I rushed? Was my mindset wrong? Should I be using a different technique? And so on. However, sometimes practice is optimal, and complications are simply the inevitable result of intrinsic risk; in such situations, changing practice can only mean worsening it. Errors of omission (failing to perform needed interventions) should not be judged as worse than errors of commission (complications of the intervention).
12. When everything is done right, and something bad happens, everything was still done right.
13. Learn from near-misses more than from complications; they are more common and it’s safer for everyone. But to do this, you must acknowledge sticky situations, not ignore them or gloss over them; the tricky or “challenging” case should not make you applaud that you had the moves to recover from it, but to ask how you can prevent it in the future.
14. Support each other when complications occur, as some amount of self-blame is common, and can easily become excessive and harmful — even when an error truly was made.

References

A-fib in the ICU: Drikite L, Bedford JP, O’Bryan L, et al. Treatment strategies for new onset atrial fibrillation in patients treated on an intensive care unit: a systematic scoping review. Crit Care. 2021 Jul 21;25(1):257. doi: 10.1186/s13054-021-03684-5. PMID: 34289899; PMCID: PMC8296751.