#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]

#23 – Essentials of Intubation



LISTEN TO THE PODCAST HERE



This is actually a special episode for the PAINE Podcast as I have the opportunity to do a joint-interview podcast with Chip Lange from TOTAL EM.  This was the first time I got to dabble with a conversational-style podcast and I think it went pretty good.  Chip and I had a great time doing it and will most definitely be doing more of these in the future.


One of the many saying my Army Airborne Ranger dad has instilled in me growing (and one that I still use today) is the seven “P” approach to accomplishing tasks:

Proper

Planning

and

Preparation

Prevents

Piss

Poor

Performance

 

What is nice about this saying is that it applies very nicely to the steps of intubation as well.


Prepare

You need to to have everything at the bedside you MIGHT need prior to any intubation attempt.  This includes equipment, medications, and any personnel or team members who will assist.  If you even suspect this could be a difficult airway, you should have your plan B and plan C options in the room to ward off the evil spirits.

  • Endotracheal tubes (3 sizes), stylets, bougies, syringes
    • Test the balloons on all the tubes
  • Laryngoscope
    • Multiple blades and handles
    • Check the lights
    • If using video, plug it in and make sure it turns on
  • Patent IV lines x 2
  • Suction
  • Cardiac and pulse oximetry monitor
  • Bag-valve mask
  • End-tidal CO2 monitor
  • Medications
    • Drawn up and labeled
    • Concentration read aloud

This also gives you the opportunity to talk with you team about the plan for intubation (how many attempts, progression should plan A, steps of what will happen during the intubation and everyone’s roles during the procedure, etc..), as well as reviewing assisting maneuvers (external laryngeal manipulation, etc.).

 

Preoxygenate

In order to decrease any deoxygenation-related issues during the intubation attempt, your patient should recieve 100% oxygen at 15 liters per minute through a non-rebreather mask for 3-5 minutes.  This will properly de-nitrogenate and super-saturate all the hemoglobin and give you the time you need to visualize and intubate.

preoxygenation

 

Position

“EAR HOLE TO CHEST HOLE”

esn

For ideal visualization, you want to position your patient so that their external auditory meatus lined up to the sternal notch

 

 

Premedicate

There are several different medications you can give for premedication purposes to modify the physiologic response during intubation (lidocaine, opiates, atropine, defasculating agents, etc..), but the main one is the sedative.  It is generally poor form to paralyze someone before you sedate them.  There are several medications you can choose from for sedation in intubation:

  • Ketamine – 1-2mg/kg IV
    • My ideal sedative
  • Etomidate 0.3mg/kg IV
    • Less hemodynamic compromise
    • Can cause adrenal suppression
  • Propofol – 1.5-3mg/kg IV
    • Can cause hemodynamic instability

 

Paralyze

There are 2 choices for classes of paralytics:

  • Depolarizing
    • Succinylcholine – 1.5-2mg/kg IV
    • Rapid onset, shortest duration of action
    • Caution in burn/crush injuries, hyperkalemic patients
  • Non-Depolarizing
    • Rocuronium – 1.2mg/kg IV
    • Vecuronium – 0.3mg/kg IV

 

Pass The Tube

Once you patient is properly sedative and paralyze, you can proceed to laryngoscopy.

 

Post-intubation Assessment

Capnography

This is used for confirmation of correct placement of the endotracheal in the trachea and tests for end-tidal CO2.  There are 2 main types:

  • Qualitative
    • Color change calorimeter
    • Attaches to end of endotracheal tube and detects CO2 by changes in exhaled pH

 

chemical

GOLD IS GOOD

  • Quantitative
    • Continuous Waveform Capnography
      • Gold standard
      • Gives you a visual waveform to see if the ventilations are adequate

screen-shot-2016-11-22-at-4-21-23-am

Securing the Tube

Once you know you are in the right spot and have been confirmed by capnography, you need to secure the tube.  There are different ways to achieve and I often defer to the respiratory therapist or nurse on how they want it secured.  There are commercial devices that lock the tube in place and secure using velcro straps, all the way to the old standby of adhesive tape.  This is a great site that shows several different ways you can secure the endotracheal tube (http://aam.ucsf.edu/article/securing-endotracheal-tube).

afbytewb

Radiography

Chest xray is the gold standard for the radiographical confirmation of endotracheal placement, as well as ensuring the proper depth.  The ideal position for the tube depth should be 3-5cm from the carina or at T3-4 position.

ett-ideal-position

Josh Farkas (PulmCrit) did a great review on endotracheal tube positioning and depth just last week.

 

Ultrasound is being used more frequently as a confirmatory tool for endotracheal tube placement.

 

Great review by EmDocs on ultrasound for endotracheal tube confirmation.

 

Sedation/Analgesia

Now that the tube is in place, secured, and confirmed, you are done right?  WRONG!!!  Your patient now has a tube shoved into the tracheal and it is a tad uncomfortable.  Postintubation sedation/analgesia is PARAMOUNT for good patient care.

  • Sedation
    • Ketamine – 0.1-0.5mg/kg bolus and 0.1-0.5mg/kg/hr infusion
    • Propofol – 5mcg/kg bolus and 5-50mcg/kg/hr infusion
    • Midazolam – 0.05mg/kg bolus and 0.025mg/kg/hr infusion
  • Analgesia
    • Fentanyl – 2mcg/kg bolus and 1mcg/kg/hr infusion
    • Hydromorphone – 0.5-1mg/kg bolus and 0.5-3mg/kg/hr infusion
    • Morphine – 5-10mg/kg bolus and 2-30mg/hr infusion

 

You should be shooting for a Richmond Agitation Sedation Scale (RASS) of -1 to -3 for adequate sedation following intubation.

rass-score

 


Really good intubation checklist from Scott Weingart of EmCrit


References

  1. http://lifeinthefastlane.com/ccc/rapid-sequence-intubation/
  2. http://emcrit.org/podcasts/emcrit-intubation-checklist/
  3.  Weingart SD, Levitan RM.  Preoxygenation and Prevention of Desaturation During Emergency Airway Management.  Annals of Emergency Medicine.  2012;59(3):165-175.
  4. http://www.capnography.com/Emergencydevice/emergencyintubtion.htm
  5. http://www.capnography.com/new/emergency-intubations
  6. http://www.capnography.com/new/emergency-intubations?id=216
  7. http://lifeinthefastlane.com/ccc/capnography-waveform-interpretation/
  8. http://www.derangedphysiology.com/main/core-topics-intensive-care/mechanical-ventilation-0/Chapter%201.2.3/endotracheal-tube-detail
  9. http://emcrit.org/podcasts/post-intubation-sedation/
  10. https://coreem.net/core/post-intubation/