Tasty Morsels of EM 074 – #FRCEM Oxygen Extraction Ratio & Aa Gradient

I’m entering a few months prep for the UK and Ireland exit exam in Emergency Medicine: the FRCEM. I’ll be adding lots of little notes on pearls I’ve learned along the way. A lot of my revision is based around the Handbook of EM as a curriculum guide and review of contemporary, mainly UK guidelines. I also focus on the areas that I’m a bit sketchy on. With that in mind I hope they’re useful.

You can find more things on the FRCEM on this site here.

Mainly from LITFL

  • DO2/VO2 relationships
    • DO2 = oxygen delivery
    • VO2 = oxygen consumption
    • O2ER is oxygen extraction ratio and is ratio of VO2 to DO2 [O2ER = VO2 / DO2]
    • Normally VO2 = 250ml/min and DO = 1000ml/min therefore O2ER = 25%. In other words oxygen delivery is usually well in excess of oxygen consumption
    • the critical O2ER is about 70% and beyond this things don’t go well
  • The Alveolar-arterial gradient
    • Aa Gradient = PAO2-PaO2
    • PAO2 comes from the alveolar gas equation
      • PAO2 = PiO2 – PaCO2/0.8
      • remember PiO2 = 0.21 x (760 – 47) [at sea level]
    • PaO2 comes from your ABG
    • Normal Aa gradient increases with age.
    • In a hypoxic patient a normal Aa gradient suggests hypoxia is due to 1) hypoventialtion (eg opiates) or 2) reduced FiO2
    • Increased Aa gradient found in V/Q or shunt or increased O2ER or diffusion defect

The post Tasty Morsels of EM 074 – #FRCEM Oxygen Extraction Ratio & Aa Gradient appeared first on Emergency Medicine Ireland.

Elemental EM: Pancreatitis

This week’s Elemental EM features how to take a simple pancreatitis case a step further.

Author: Courtney Cassella, MD (@Corablacas, EM Resident Physician, Icahn SoM at Mount Sinai) and Jacqueline Paulis, MD (EM Resident Physician, Icahn SoM at Mount Sinai) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, SAUSHEC, USAF)

Clinical Case:

A 58-year-old man with a history of hypertension and non-insulin dependent diabetes presents with 2 days of worsening abdominal pain. Pain is epigastric and sharp; he has never experienced this before. He endorses nausea, 3 episodes of nonbloody nonbilious emesis, and decreased appetite. He denies chest pain, SOB, changes in bowel habits, urinary symptoms, or surgical history. He smokes and drinks daily; denies illicit drug use. The patient appears slightly uncomfortable secondary to pain but is in no acute distress, his abdomen is tender to palpation in the epigastrium with no rebound or guarding. He is placed NPO, given intravenous fluids, anti-emetics, and analgesia. His lipase returns at 1,336. He is admitted to medicine for further management.


This is a common example of alcoholic pancreatitis. In most cases the clinical picture and elevated lipase is sufficient. If the patient is stable and non-toxic the management and disposition are straightforward. Here are prompts to add nuance to a presentation about pancreatitis.

What would prompt you to CT image this patient?1,2

Acute pancreatitis. Case courtesy of Dr. Nikhil Rao, Radiopaedia.org, rID: 11083
  • Diagnostic uncertainty
    • Diagnosis of pancreatitis is based on at least two of three criteria
      • 1) Clinical presentation consistent with acute pancreatitis
      • 2) Serum lipase or amylase elevated above upper limit of normal
      • 3) Imaging findings characteristic of acute pancreatitis
    • In short, if the lipase is normal but the clinical presentation is highly suspicious for pancreatitis, image the patient.
    • Alternatively, imaging can be used to evaluate other entities in the differential.
  • Confirmation of severity based on clinical predictors of severe acute pancreatitis
    • However, for the EP, CT scoring systems are not superior to clinical scoring systems in predicting prognosis and severity of disease.4
  • Failure to respond to conservative treatment or clinical deterioration
    • As an emergency physician, we will not typically see when a patient does not respond to conservative management.
    • Consider CT imaging in an acutely decompensating patient, in part to evaluate for complications of pancreatitis.

Routine emergency department CT imaging in pancreatitis is rare because

  • Most patients have uncomplicated disease
  • There is no evidence that early CT improves outcomes4
  • The yield is low as early CT results demonstrating peripancreatic fluid collections (i.e. pseudocyst) or pancreatic necrosis early in presentation generally require no treatment.2
  • It does not improve clinical outcomes5,6
  • Risks of IV contrast

Furthermore, the International Association of Pancreatology and American Pancreatic Association guidelines state optimal timing for initial CT is 72-96 hours after onset of symptoms because the extent of necrosis may not manifest until that point.

**Note: This is different from additional imaging such as ultrasound. Right upper quadrant biliary ultrasound is often performed to evaluate etiology of pancreatitis.

What if scenarios to discuss complications:

The patient receives several boluses of IV fluids and develops pulmonary edema requiring intubation. You note his abdomen has become progressively more distended and tense. The nurse notifies you the patient hasn’t had any urine output from his foley and his ventilation requirements are increasing.

Abdominal Compartment Syndrome

  • Definition: Intra-abdominal pressure > 20 mmHg with new onset organ failure
  • Causes: Tissue edema from aggressive fluid resuscitation, inflammation, ascites, and ileus
  • Diagnosis: Monitor with serial measures of urinary bladder pressures
  • Treatment: Surgery consultation for surgical decompression

 

The patient has had symptoms for 4 days and says he has a history of “something weird when they look at my pancreas”. You decide to image the patient and find2, 7, 10

  • Acute peripancreatic fluid collection
    • Not walled off
    • Often resolves spontaneously
  • Pancreatic pseudocyst8
    • Walled off fluid collection outside pancreas with no epithelial lining. No significant necrosis.
    • Develops 4 weeks after acute pancreatitis episode
    • Treatment: Consider draining if > 5-6 cm in diameter, causes pain, or gastric outlet obstruction
  • Necrosis8
    Walled off necrosis. Case courtesy of A. Prof Frank Gaillard, Radiopaedia.org, rID: 29888
    • Can affect both pancreas and surrounding tissue
    • May or may not be walled off
    • Can be sterile or become infected; majority are monomicrobial gut flora
    • Diagnosis: Imaging, consider infected necrosis if clinical deterioration
    •  Management:
      • Often medical treatment is sufficient, particularly if patient is improving
      • Consider empiric antibiotics and early surgical consultation in an unstable patient (suspect infected necrosis)
        • Carbapenem9
        • Other antibiotic regimens for example Fluoroquinolone – or – Metronidazole AND Ceftazidime or Cefepime can be considered however for isolated infected pancreatic necrosis a 2010 Cochrane Review found no benefit with these antibiotics. 9
  • Splanchnic Venous Thrombosis
    • Splenic or portal vein thrombosis
    • May be incidentally found on imaging
    • Treatment:
      • Anticoagulate, particularly if clot extension into portal or superior mesenteric veins. May resolve with supportive therapy for pancreatitis.
  • Pseudoaneurysm
    • Communication caused by erosion of the pancreatic or peripancreatic artery
    • Pulsatile mass
    • Risk of rupture
    • Treatment: Vascular surgery consultation, operative repair

 

Extrapancreatic Complications2

  • Shock, multiorgan dysfunction, renal failure, respiratory failure, liver failure
  • Hypotension, Hypovolemia, SIRS
  • Third spacing
    • Pericardial effusion
    • Ascites
    • Pleural effusion
    • Pulmonary edema
  • Hypoxemia, Respiratory failure, Atelectasis, Acute respiratory distress syndrome (ARDS)
  • Disseminated intravascular coagulation
  • Myocardial infarction
  • Retroperitoneal hematoma
  • Alcohol withdrawal

 

References/Further Reading:

  1. Working Group IAP/APA Acute Pancreatitis Guidelines. IAP/APA evidence-based guidelines for the management of acute pancreatitis. Pancreatology. 2013; 13(4) Supp 2: e1-15.
  2. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8th Edition. Chapter 79: Pancreatitis and Cholecystitis.  Besinger B, Stehman CR. Pancreatitis and Cholecystitis.Tintinalli JE, et al. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016. http://eresources.library.mssm.edu:2744/content.aspx?bookid=1658&sectionid=109430493 Accessed May 08, 2017.
  3. LITFL: Pancreatitis ; https://lifeinthefastlane.com/ccc/pancreatitis/
  4. Bollen, T.L., Singh, V.K., Maurer, R., Repas, K., van Es, H.W., Banks, P.A. et al. A comparative evaluation of radiologic and clinical scoring systems in the early prediction of severity in acute pancreatitis. Am J Gastroenterol. 2012; 107: 612–619
  5. Spanier, B.W., Nio, Y., van der Hulst, R.W., Tuynman, H.A., Dijkgraaf, M.G., and Bruno, M.J. Practice and yield of early CT scan in acute pancreatitis: a Dutch Observational Multicenter Study.Pancreatology. 2010; 10: 222–228
  6. Mortele, K.J., Ip, I.K., Wu, B.U., Conwell, D.L., Banks, P.A., and Khorasani, R. Acute pancreatitis: imaging utilization practices in an urban teaching hospital – analysis of trends with assessment of independent predictors in correlation with patient outcomes. Radiology. 2011; 258: 174–181
  7. Tatco, V, Datir A, et al. Acute Pancreatitis. https://radiopaedia.org/articles/acute-pancreatitis. Accessed July 15, 2017
  8. Mergener K and Baillie J. Acute Pancreatitis. BMJ. 1998; 316(7124): 44-48. PMC: 2665345.
  9. Villatoro E, Mulla M, Larvin M. Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis. The Cochrane Database of Syst Rev. 2010;(5):CD002941. [PubMed]
  10. Lankisch PG, Apte M, Banks PA. Acute Pancreatitis. Lancet. 2015; 386(9988):85-96.

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Stryker’s MultiGen 2RF Generator for Facet Joint Ablations Cleared by FDA

Stryker, a company best known for orthopedic devices, won FDA clearance to introduce its MultiGen 2 RF Generator in the U.S. The device is used to treat pain deriving from facet joints in the spine by delivering radiofrequency energy that ablates targeted tissues. Compared to the previous version of the device, Stryker claims that the MultiGen 2 provides improved control, reliability, and procedural efficiency.

The device produces twice the amount of power compared to most standard devices of this type, getting up to temperature quicker with fewer opportunities for errors to occur. A single button starts the procedure, while removing electrodes is not necessary when creating strip lesions that are the signature of facet joint RF ablation.

There are a number of settings that can be adjust depending on the patient needs and physician preferences, allowing for quick turnaround and intuitive pre-op steps that make it easy to get started.

Via: Stryker…