Podcast #260: Preoxygenation

Author: David Rosenberg, M.D.

Educational Pearls

  • Preoxygenation is done before rapid sequence intubation, and should be done even if SaO2 is at 100%.
  • Preoxygenation is done to fill the lungs with oxygen rather than ambient air, which is only 20% O2. While the patient is paralyzed, the O2-filled lungs will continue to oxygenate venous blood, buying you more time for intubation.  
  • BiPAP is an effective tool for pre-oxygenation.

References: https://lifeinthefastlane.com/ccc/preoxygenation/

Podcast #247: D-Dimer

Author: Michael Hunt, M.D.

Educational Pearls

  • In the recent YEARS study, investigators checked every patient with suspicion for PE with a D-dimer, using a modified Wells score for risk stratification. The goal of the study was to show that CT scan usage could safely reduced using this screening method.
  • The Wells Criteria measures they used to stratify risk were: PE mostly likely dx, hemoptysis, and evidence of DVT. If the d-dimer was 1, but the patient had none of the Wells criteria, the patient did not get a CT. If the patient had any of the criteria, but the d-dimer was only 0.5, the patient did not get a CT scan.
  • The investigators reduced  CT usage by 14% using the new criteria, with no significant increase in morbidity and mortality.

References: van der Hulle et al. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. The Lancet. 2017

Podcast #246: Patent Foramen Ovale

Author: Jared Scott, M.D.

Educational Pearls

  • The foramen ovale (FO) connects the left and right atria to allow oxygenated blood to bypass the developing lungs, it usually closes at birth but for some it remains patent (PFO).
  • A PFO allows clots to cross from the venous to arterial circulation, increasing the likelihood of stroke.
  • PFO is present in 25% of general population, present in 50% of those with stroke of unknown cause, and very common those with stroke under 50 years old.
  • Treat with anticoagulation or surgical correction.

References: http://www.heart.org/HEARTORG/Conditions/More/CardiovascularConditionsofChildhood/Patent-Foramen-Ovale-PFO_UCM_469590_Article.jsp#.WarsZZN95E

Podcast #232: HAPE

Author: Gretchen Hinson, M.D.

Educational Pearls

  • High-Altitude Pulmonary Edema (HAPE) is caused when hypoxemia due to low ambient pO2 leads to breakdown and constriction of the pulmonary vasculature leading to edema.
  • HAPE is very rare under 8000 ft, but common over 10000 ft (6%). Over 18,000 ft the incidence is very high (12-15%).
  • Symptoms include dyspnea, cough, weakness and chest tightness.
  • Signs include hypoxemia, crackles, wheezing, central cyanosis, tachypnea and tachycardia.
  • Drugs that reduce pulmonary resistance have been shown to help, but increased oxygenation and descent are the best treatments.

References: http://emedicine.medscape.com/article/300716-overview

Podcast #222: Wells Criteria for PE

 

Author: Michael Hunt, M.D.

Educational Pearls

  • Wells Criteria was initially designed to screen patients for further workup for PE.  
  • Aspects of the Wells Criteria include: signs and symptoms of DVT (3 points), PE most likely dia (3 points), HR > 100 (1.5 points), immobility for > 3 days or surgery in last 4 weeks (1.5 points), documented history of PE (1.5), hemoptysis (1), treatment for cancer in last 6 mo (1).
  • ACEP uses a score of less than or equal to 4 to define “low risk.” Greater than 4 is “high risk”.
  • Use Wells to guide clinical decisions about PE workup.

References: http://www.ebmedicine.net/media_library/files/1212%20Pulmonary%20Embolism

Podcast #208: Vocal Cord Dysfunction

Author: Martin O’Bryan M.D.

Educational Pearls:

  • Vocal cord dysfunction can mimic other causes of stridor, such as asthma and upper airway obstruction.
  • Patients are often very anxious because of the difficulty of inspiration.
  • The definitive diagnosis is laryngoscopy that must be done by a pulmonologist.
  • The treatment is general reassurance, asthma medications will not help. CPAP and heliox can be used to help with the stridor.
  • Benzodiazepines can be used to reduce the associated anxiety.

References: https://asthmarp.biomedcentral.com/articles/10.1186/s40733-015-0009-z

Podcast #182: Syncope and PE

Run Time: 3:44 minutes

Author: Aaron Lessen, MD

Educational Pearls:

  • A new Italian study has been released, which looks at the prevalence of Pulmonary Embolism (PE) in patients admitted for syncope.
  • This study examined all patients admitted with syncope, regardless of their clinical picture, and worked them up for PE, which included wells score, D-dimer, and CT
  • Study demonstrated 1 out of 6 pts admitted for syncope had a PE.
  • Despite the headlines this study is making in the news, it is difficult to make conclusions. The study was not perfect, and mainly looked at a sick population of patients (only those who warranted admission) who had many comorbidities.  Until further studies are conduction, current practice should be to only work up syncope patients for a PE if they are exhibiting related signs and symptoms.

Link to Podcast: http://medicalminute.madewithopinion.com/syncope-and-pe/

References: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/SymptomsDiagnosisMonitoringofArrhythmia/Syncope-Fainting_UCM_430006_Article.jsp

Podcast #151: The Most Common Fatal Ingestions

be53de65-7db5-4265-b1e5-4d2022d56af9Run Time: 8 minutes

Author: Peter Bakes M.D.

Educational Pearls:

  • CO poisoning is one of the most common fatal accidental ingestions.
  • Two main causes of CO poisoning are 1) SI – such as a car left running in closed space, which accounts for ⅓ of CO poisoning 2) Any tool/appliance that runs on fuel and produces CO from incomplete combustion of that fuel.
  • Exposure to a CO level of 50-100 parts per million for a few hours is when patients start to feel symptomatic. Where as, a CO2 in ambient air is at 400 parts per million.
  • Pathophysiology – CO has a 120 times higher affinity to hemoglobin than O2, CO causes functional anemia, CO causes lipid peroxidation, CO binds to cytochromes which inhibits energy production, and CO binds to myoglobin which decreases cardiac function.
  • The classic clinical presentation of CO poisoning is flu-like illness with a low energy state. CO can also cause ataxia, cognitive problems, and cerebellar dysfunction due to its toxicity to the brain. It is one of the only diseases which causes headache and chest pain at the same time.
  • In the ED test a carboxyhemoglobin level – greater than 20% is when the patient is in need of immediate treatment.
  • In the ER patients are placed on an O2 non-rebreather, or in more severe cases can be placed in hyperbaric chamber.
  • CO has a half-life of 4-6 hours in normal air with an O2 concentrations of 21%. With the non-rebreather the half-life is decreased to 60-90 minutes, and in a hyperbaric chamber the half-life is again decreased to 20-30 minutes.
  • Patients are treated until they become asymptomatic. Patients further removed from the exposure may need neuro-psychiatric testing for prolonged cognitive problems caused by hypoxia and lipid peroxidation.
  • Interestingly, families who believe they lived in a haunted house may have been exposed to toxic CO and experienced delusions and delayed manifestations when in the “haunted house”, but when leaving the house the family will begin to feel better.

Link to Podcast: http://medicalminute.madewithopinion.com/the-most-common-fatal-ingestion/

References: https://medlineplus.gov/carbonmonoxidepoisoning.html

Podcast #129: SIPE

8a3adf9a-ecfa-4999-b2f4-a9a2beb95c91Run Time: 4 minutes

Author: Suzanne Chilton M.D.

Educational Pearls:

  • SIPE or SWIPE stands for Swimming Induced Pulmonary Edema and usually occurs in young people without previous pulmonary problems or CHF.
  • Happens more often in cold water, and could be a combination of increased cardiac output, increased permeability of capillary bed and increased pressure in capillary bed.
  • Presents either during the swim or after the swim – most patients will be hypoxic and have to be pulled out of the water. Patients will have rales and can have hemoptysis.
  • Treatment is symptomatic, most episodes resolve in 12-24 hours, but patients have an increased risk of recurrence in the future.
  • Another swimming related issue is shallow water syncope – which happens in people who are extremely good swimmers.
  • Generally happens when the patient is trying to hold their breath underwater for a long period of time.
  • Hypercarbia is what causes the urge to breath, and good swimmers can resist this urge. Up to the point that they suddenly become hypoxic, lose consciousness, and may drown.

Link to Podcast: http://medicalminute.madewithopinion.com/sipe/

References:  http://www.endurancetriathletes.com/sipe.html

http://ndpa.org/loss-of-consciousness-in-breath-holding-swimmers/

Podcast #94: Steroids in Asthmatic Kids

f4f30e92-1942-47d0-8b05-c6164215b8cdRun Time: 2 minutes

Author: Dr. Chris Holmes

Educational Pearls:

  • A recent study investigated the difference between prednisone and one time dexamethasone dose given to children with asthma in the emergency room.
  • There was no difference in PRAM score or hospitalization after initial dose in either steroid group.
  • There was a slight difference in repeat dosing with prednisone in the dexamethasone group compared to the prednisone group – 13% vs. 4%.
  • One disadvantage of prednisone is that it tastes like diesel fuel – kids are more likely to vomit – dexamethasone tabs dissolves in water, applesauce, etc. and dexamethasone is a one-time dose in the ER.

Link to Podcast:  http://medicalminute.madewithopinion.com/steroids-in-asthmatic-kids/

References:  http://www.annemergmed.com/article/S0196-0644(15)01154-3/abstract