PAINE #PANCE Pearl – Emergency Medicine



Question

You have a patient in the ED with an aortic dissection and are managing them while awaiting the cardiovascular surgeon to arrive.

  1. What are the two most important things to control?
  2. How do you go about doing that?


Answer

  1. The main aims of acute medical management of aortic dissections are to decrease the rate of left ventricular contraction and decrease the velocity of the contraction, which will overall decrease the shear stress at the site of the tear and slow progression.
  2. Start with intravenous beta-blockade and titrate to a heart rate of 60 betas/minute
  1. If systolic blood pressure is > 120 mmHg after successful beta-blockade, then add a vasodilator or afterload reducer.

For a deep dive into aortic dissections, check out the podcast



References

  1. Hiratzka LF, Bakris GL, Beckman JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with Thoracic Aortic Disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation. 2010; 121(13):e266-369. [pubmed]
  2. Tsai TT, Nienaber CA, Eagle KA. Acute aortic syndromes. Circulation. 2005; 112(24):3802-13. [pubmed]

#36 – Basics of the Ventilator with Wes Johnson, PA-C



***LISTEN TO THE PODCAST HERE***

 



Guest Information

 

Wes Johnson, MSPAS, PA-C, (soon to be), DHSc was a former student of mine at UAB and was a respiratory therapist prior to PA school.  He is the Regional Director of Clinical Education for Island Medical Management Emergency group in North Alabama.  He won the Preceptor of The Year award from UAB in 2016 and currently finishing up his doctorate degree from A.T. Still University.

Twitter – @wesj2288



Disclaimer

 

For the purposes of this podcast and post, we will be using the Puritan Bennett 840 ventilator (pictured below).  All the term we use are synonymous with all vents, but the screens will be different.

Puritan Bennett 840


Big Concepts of The Ventilator

 

  1. Mode
    1. Assist Control (AC)
      1. Every breath is either a machine driven (set by rate) or fully assisted (initiated by the patient)
        1. Uses either pressure (ACPC) or volume (ACVC)
    2. Synchronized Intermittent Mechanical Ventilation (SIMV)
      1. Set number of machine driven breaths, and patient intitated breaths are partially assisted
    3. Pressure Support (PS)
      1. No machine driven breaths and all breaths are initiated by the patient and partially assisted
  2. Delivery
    1. Pressure
      1. Static Controls
        1. Pressure
        2. Time (inspiratory)
        3. Peak flow
      2. Variable Factors
        1. Volume
        2. Total flow
    2. Volume
      1. Static Controls
        1. Tidal volume (cc)
        2. Flow (L/min)
      2. Variable Factors
        1. Pressure
  3. Positive End Expiratory Pressure (PEEP)
    1. The pressure left in the circuit at the end of expiration
    2. Prevents alveolar collapse and improves oxygenation
    3. Can cause barotrauma and affect hemodynamics

Static Controls

 

(For this section, refer back to the vent picture above)

  1. Fraction of Inspired Oxygen (FiO2)
    1. Start at 100% and titrate down to 21%
  2. f (machine breath rate)
  3. Control
    1. Pressure Control (PC)
      1. Inspiratory pressure (Pi)
        1. Peak pressure in circuit
        2. Initial setting = < 20 cm H20
      2. Inspiratory time (I-time)
        1. Initial setting = 1.25 seconds
    2. Volume Control (VC)
      1. Vt (tidal volume of each breath)
        1. Initial setting = 6-8 cc/kg IBW
      2. Vmax (flow rate)
  4. Spontaneous Support
    1. Trigger for spontaneous support
      1. Volume = V-trig
      2. Pressure = P-trig
    2. Pressure Support (PS)
      1. I was always taught at least 5 cm H20 to overcome circuit resistance

Real-Time Controls

 

  1. Flashing “C” and “S”
    1. Lets you know what breaths are controlled (machine) or spontaneous (patient)
  2. Airway Pressure
    1. Ppeak (max airway pressure)
      1. A marker of resistance
    2. Pmean (average airway pressure)
      1. A measure of alveolar pressure
    3. Pplat (small airway and alveoli pressure)
      1. A measure of compliance
  3. fTotal (machine + spontaneous breaths)
  4. I:E (inspiratory:expiratory ratio)
    1. Normal = 1:2 (at rest)
    2. Inverse ratio (2:1) can improve oxygen due to intention auto-PEEP

Wes Johnson’s Approach to Setting Up a Ventilator (after RSI)

 

Mode: AC

Vt: 6-8 mL/kg based on pt’s IBW

Rate: 12-16 bpm

FiO2: 100%

PEEP: 5.0

At the 5-minute mark:

  • Check an ABG
    • Titrate FiO2 off of PaO2 and pulse oximeter
    • Adjust minute ventilation off of PaCO2 and/or ETCO2


References

  1. Respiratory Review YouTube Channel https://www.youtube.com/channel/UCtaRF58UDVthvH36YYCttng
  2. Deranged Physiology.  Mechanical Ventilation. http://www.derangedphysiology.com/main/core-topics-intensive-care/mechanical-ventilation-0
  3. Weingart SD – “Spinning Dials – How to Dominate the Ventilator” – https://emcrit.org/wp-content/uploads/vent-handout.pdf
  4. Weingart SD. Managing Initial Mechanical Ventilation in the Emergency Department. Annals of emergency medicine. 2016; 68(5):614-617. [pubmed]
  5. Air Link Regional West – “Initial Adult Ventilator Settings” – https://www.rwhs.org/sites/default/files/airlink-factsheet-ventsettings.pdf
  6. Open Anesthesia. Modes of Mechanical Ventilation. https://www.openanesthesia.org/modes_of_mechanical_ventilation/
  7. Modern Medicine Network.  A Quick Guide to Vent Essentials. http://www.modernmedicine.com/modern-medicine/content/tags/copd/quick-guide-vent-essentials
  8. Tobin MJ. Extubation and the myth of “minimal ventilator settings”. American journal of respiratory and critical care medicine. 2012; 185(4):349-50. [pubmed]

PAINE #PANCE Pearl – Emergency Medicine



Question

 

What are the 5 main life-threatening causes of chest pain?


Answer

 

The 5 main life-threatening causes of chest pain you should ALWAYS think of are:

  1. Acute Myocardial Infarction
  2. Pulmonary Thromboembolism
  3. Pneumothorax (risk of tension)
  4. Pericarditis (risk of tamponade)
  5. Aortic Dissection

There are a few others that should also cross your mind:

  1. Esophageal Rupture (Boerhaave’s Syndrome)
  2. Acute Chest Syndrome in Sickle Cell patients
  3. Unstable angina

 


References

  1. The Five Deadly Causes of Chest Pain Other than Myocardial Infarction. JEMS. 2017
  2. Chest Pain.  Life in The Fastlane.
  3. Woods WA, Young JS, Just JS. Emergency Medicine Recall.  2000.

 

PAINE #PANCE Pearl – Emergency Medicine



Question

What are 3 pretest probability scoring systems used to evaluate patients with a suspected pulmonary thromboembolism?



Answer

There are 3 validated pretest probability scoring systems that can be used to help clinicians decide who can be sent home, who needs a D-dimer, and who goes straight to CT for suspected PTE.

 

Wells Criteria

 

Developed – 1998

Revised – 2000

Simplified – 2001

slide18

 

Geneva Score

 

Developed – 2001

Revised – 2006

Simplified – 2008

slide20

 

Pulmonary Embolism Rule-Out Criteria (PERC) Score

 

Developed – 2008

This score is used AFTER the patient is determined to be low-risk using the Well’s or Geneva score.  In patients who are low-risk and PERC negative, there is only a 1.6% false-negative rate for missed PTE.  Any one of these would deem the patient PERC positive.

slide22

 

Why is this so important?

Although it does help us in deciding who maybe at higher risk of PTE, I personally feel these scoring systems help us document who DOES NOT need work-up.  There are quite a few patients who come in with non-specific chest pain or shortness of breath, and you should ALWAYS entertain the idea of PTE in these patients.  But, not every single one of these patients need a d-dimer or CTA.  Better yet, some of these patients can be discharged home without any investigation if they are low-risk and PERC negative.

 

Below is an algorithm I modified from Jeff Kline using these clinical decision instruments.

slide64


All these images are slides from my talk at the 2015 AAPA Conference


References

  1. Wells PS, Ginsberg JS, Anderson DR. Use of a clinical model for safe management of patients with suspected pulmonary embolism. Annals of Internal Medicine. 1998;129(12):997-1005. [pubmed]
  2. Wells PS, Anderson DR, Rodger M. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thrombosis and Haemostasis. 2000;83(3):416-20. [pubmed]
  3. Wells PS, Anderson DR, Rodger M. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Annals of Internal Medicine. 2001;135(2):98-107. [pubmed]
  4. Wicki J, Perneger TV, Junod AF, Bounameaux H, Perrier A. Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score. Archives of Internal Medicine. 2001;161(1):92-7. [pubmed]
  5. Le Gal G, Righini M, Roy PM. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Annals of Internal Medicine. 2006;144(3):165-71. [pubmed]
  6. Klok FA, Mos IC, Nijkeuter M. Simplification of the revised Geneva score for assessing clinical probability of pulmonary embolism. Archives of Internal Medicine. 2008;168(19):2131-6. [pubmed]
  7. Kline JA, Courtney DM, Kabrhel C. Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. Journal of Thrombosis and Haemostasis. 2008; 6(5):772-80.  [pubmed]