Thursday, June 26, 2014

Arterial Waveform Analysis Devices

Image 1: From PiCCO @ Bedside, iOS Mobile app [1]. 

Due to the results of the March 2014 "ProCess Trial" indicating that early goal directed therapy in septic shock did not improve outcomes [2] , there has been less interest in using pulse contour analysis devices to optimize fluid management in the critically ill patient. 

The main reason for this is that these devices, even though less invasive then the pulmonary artery catheter still require at the minimum an arterial line and in addition (depending on device) a central venous catheter

However, before letting these devices collect dust on a shelf, I believe this tool can be still be very beneficial in two patient populations.

One, is the high risk surgical patient to optimize fluid management.
This strategy is currently termed "Goal directed Intra-operative fluid administration".

Fluid overload during surgery has been associated with [3]:

-Increased length of stay
-Bowel wall edema
-Edema organ dysfunction
-Adverse outcomes

Additionally, patients receiving fluid and hemodynamic optimization during surgery are at an decreased risk of renal impairment. 

The second type of patient that may benefit from minimally invasive cardiac output monitoring is the critically ill cardiovascular patient.

 With these patients the ICU physician is always questioning [4]:

-"Is the patient's pre-load sufficient to obtain adequate Cardiac output"?
-"Does the patient need volume (fluids) or forced diuresis"?
-"What is the patient's cardiac function"?
-"Does the patient need inotropes or pressors"?

In these patients'  not optimizing fluid management can be detrimental. 


All devices calculate cardiac output based on the traditional equation:


CO = Cardiac Output
SV= Stroke volume
HR= Heart rate 

However, each device uses a proprietary method to calculate stroke volume or a modification of the Fick principle. Below is a table I created that compares and contrast three different pulse contour analysis devices.  

Image 2: Table comparing Pulse Contour Analysis Devices.

For more information on Arterial Waveform Analysis Devices one can visit the Society of Critical Care Medicine and take the online course "Less-Invasive Hemodynamic Monitoring" [5]. 


3. Optimization of the High Risk Surgical Patient. SCCM, lecture 2014

4. Transpulmonary Thermodilution. SCCM, lecture 2014. 

Thursday, June 19, 2014

ASV Behind the Scenes

The advantage of using Adaptive Support Ventilation (ASV) is that it automatically enforces the three primary clinical goals of mechanical ventilation, which include safety, comfort, and liberation.

To accomplish these goals ASV uses rules to set lung protective boundaries. 
Many of these rules are out of view from the device operator and are not affected by operator selection of inputs. The rules fall into two categories 'hard rules' and 'soft rules' or a combination of both types.

A Hard Rule is a pre-set limit which is unaffected by the operators interaction or by measured patient lung mechanic values (a "behind the scene" action). An example of this is the minimum & maximum mandatory breath limits and I:E ratio limits.

A Soft Rule is a limit based on an operator input and/or measured values of the patients respiratory mechanics. An example of this is the minimum & maximum inspiratory pressure threshold, which is determined by the operator directly setting the PEEP (affects lower PIP threshold) and the ASV pressure limit (affects the high PIP limit).

These rules are similar to techniques used by the experienced device operator, in which one uses to optimize ventilator settings. Now the less experienced device operator can provide the same standard of care as a seasoned practitioner in regards to enforcing the clinical goals of mechanical ventilation.

In upcoming blog posts and YouTube videos I will be presenting the the ASV rules in more detail.


Richey, S. (2010). Adaptive Support Ventilation: Guidelines  Standards for Using ASV. 

Thursday, February 27, 2014

ASV & ABGS: Adjusting %Min Vol Based on Arterial Blood Gases

Adjust %Min Vol setting during ASV in regards to ABG analysis

I often get asked how do I adjust my settings during Adaptive Support Ventilation based on my arterial blood gas (ABG) results.
 Above is a snap shot of a flow chart from my new ASV guide I'm currently working on. 
This chart provides a brief overview of adjusting the percent minute volume setting based on ABG results, the guide will provide more details. 


Monday, February 3, 2014

A Synopsis of Strategies in Difficult Intra-Operative Ventilation

Image from:

“Strategies in Difficult Intra-Operative Ventilation” was a continuing education course originally presented at the 2012 American Academy of Anesthesiologist convention. 

Now the course is available online through the ASA website for continuing education units. I would not recommend this course for the ICU practitioner because it overviews strategies that we practice daily or weekly, however for the anesthesia provider that is not familiar with lung protective strategies the course may be beneficial. 

Below is a synopsis of the course and a hyperlink to the website. 

Wednesday, January 22, 2014

Updated Adaptive Support Ventilation (ASV) Book Coming

ASV Least WOB Screen Identifying Safety Rules

Yes, I made a mistake my first ASV guide was a basic synopsis and protocol of Adaptive Support Ventilation.

This frustrated you (my readers), so I decided to take it off Amazon and work on a more in-depth version.

So please be patient, this guide will be available soon.

Tuesday, January 7, 2014

What the Sales Guy Won't Tell You. Why You Won't Save $200,000 in Anesthetic Agent

In a previous post "How to Save $200,000 in Anesthetic Agent" I demonstrated how one anesthesia department could save close to a quarter of a million dollars by changing efficiency. I presented this many times using a mathematical modeling tool (Anesthesia Agent Analysis. S. Richey & R. Hazlett)  a colleague and myself created. 

Anesthesia Companies have used this same modeling in their marketing and device claims in regards to saving anesthetic agent. 

Example 1: Draeger Medicals "Low Flow Wizard" 
This is a decision support tool to help practitioners feel comfortable with using low to minimal flow anesthesia. 

Example 2: GE Healthcare's "ecoFlow"
This is GE's product to compete with & similar to the Low Flow Wizard (Draeger's was released first).


However, these tools are not novel. 

Dr. James H. Philip, the creator of "Gas Man" [1] has been a advocate, and teacher of minimal flow & closed system anesthesia for almost two decades. 
Dr. Philips software & courses demonstrate that one can provide minimal flow anesthesia using any modern day anesthesia delivery system, not just the Draeger Apollo or GE Avance with ecoFlow. 

The key factor in minimal flow anesthesia is patient safety, which translates to patient monitoring, which is not accomplished by the Low Flow Wizard or ecoFlow. These tools only look at the anesthesia device (gas uptake & system leaks) not hemodynamic status, metabolic demand, SpO2, EtCo2, rebreathed gas, etc. 

Additionally, the medical device companies marketing claims provide a false prediction of actual cost savings related to decreased anesthetic agent usage. 

In the following post I will present why you will not obtain these savings.

Thursday, December 5, 2013

Why I Do Not use Draeger Ventilator Simulators

I get asked often why do I not use other simulators in my videos.
Specifically the Draeger ventilator simulators.
It is very simple, they cannot perform the functions I need to teach modes of ventilation & pulmonary mechanics as demonstrated in the video. 

Saturday, November 16, 2013

Adaptive Pressure Control Ventilation Video Series

After finishing my videos on the mathematical models of PC-CMV, I decided to create videos on Adaptive Pressure Control (APC) ventilation.

These videos compare and contrast between APC, VC, & PC during changes in pulmonary dynamics & various patient conditions/ interactions.

Tuesday, November 12, 2013

Incorporating Proportional Assist into Ventilator Protocols

Image 1: PAV+ Work of Breathing bar. 

PAV+ may be used for the initial mode of ventilation during the acute phase of mechanical ventilation. However, from my experience I have had the most success and efficiency with PAV+ utilizing the mode to rest patients after a failed spontaneous breathing trial. After reviewing the literature it is still unclear the best way to wean or liberate a patient from PAV+. However, a traditional T-piece trail has been supported by many peer reviewed journals, so at my institution we still use a 30 minute to one hour T-Piece trial to screen patients for extubation.
How to incorporate PAV+

Tuesday, November 5, 2013

The Fastest Ambulance on TED

Whats in your pockets? Are you a Prepper or Macgyver?

In a previous post (The RT Hoarder) I mention that I carry very little on me when I'm at work. 
Yes, I believe in being prepared, however I try to practice the "Macgyver" philosophy [1], versus the "Dooms Day Prepper" mentality [2].

This post presents my Everyday Carry (EDC) [3] from when I first started in the field of respiratory therapy to what I carry now. I will describe "what is in my pockets" and why, also notice the progression throughout the years.

What items do I get rid of & what do I always need to practice the profession?

EDC as a RT student & new graduate.

Saturday, September 7, 2013

High-Fidelity Human Patient Simulators Not Needed: Links to Free Simulators

Image 1 From:

Many academic institutions have or are in the process of implementing high-fidelity human patient simulators to augment didactic teachings. Some centers are even using these simulator labs to decrease/reduce the number of hands-on clinical hours.
Personally, I believe these very high cost simulator labs are a scam and more time should actually be focused at bedside with a dedicated clinical preceptor.

Note- my views are from participating in various curriculum's from the schools with very little resources to highly funded skills labs.

My argument against high-fidelity human patient simulators

1.       Cost- the institution has to invest in space, building a simulation lab, lab equipment overhead cost (e.g. electricity, heating & cooling), and staffing. I believe these funds can be better allocated.

2.        No proof- There is little evidence indicating high fidelity simulator labs provide additional benefits versus cheaper methods of simulation (e.g. role playing, actors, etc). Additionally studies supporting the high fidelity labs have been performed by the labs themselves, so I believe there is some biases here.

3.       Hours- many simulator labs you may only visit a few times a semester. When I was attending graduate school we only went to the simulator lab twice a semester. Conversely, in paramedic school we practiced and went over patient assessment skills in every class. Additionally, with simple simulators I can use these anywhere at any time.

4.       Groups- Usually, the simulation lab is a large group exercise with very little individualized hands on experience.

5.       Scenarios- Usually during your scheduled time your group only participates in one scenario. Conversely, with other simulators you can individually go over multiple scenarios in the same amount of time.

Links to Free Simulators to augment your education (Click Hyperlinks)

1.       Draeger Ventilator & Anesthesia Delivery System Simulators:

2.       Hamilton Medical Ventilators. Note this is just a link to their home page, you need to select a specific product to access the simulator:

4.       Robert Chatburn’s Ventilator simulators. My favorite, true mathematical models great for teaching and understanding modes & the variables which influence mechanical ventilation:'s_Simulators

Monday, August 12, 2013

Waveform of the Week

Waveform of the week 

I posted a patient ventilator asynchrony case on the GMEP Media Gallery.

Here is the link for viewing:

Sunday, August 11, 2013

PC-CMV Relationship of Delivered Minute Ventilation & Set Frequency

Mathematical Review of Pressure Preset Ventilation

Minute ventilation as a function of set frequency with no airflow obstruction. Minute ventilation rises toward a final plateau determined by I-time & resistance. However, compliance determines the rate of the rise of the curves.

Wednesday, August 7, 2013

Relationship of frequency to tidal volume during PC-CMV

Review of Mathematical Principles of Pressure Preset Mechanical Ventilation

This video demonstrates the relationship between set frequency to delivered tidal volume during Pressure control ventilation. Reductions in compliance or increases in frequency decrease delivered VT.

Sunday, July 14, 2013

Don't waste my time! Physician Rounds.

Image from:

Physician rounds, ICU rounds, or multi-disciplinary rounds are very important in the care and treatment of mechanically ventilated patients. It is the only time (usually only once in a 24 hour period) that many specialties can share their concerns, ideas, and goals with the attending intensivist.  The attending physician is very busy, and  responsible for the over-site of many patients, so it is ideal to present your goals during rounds.

I have worked many places and still can't believe how RT's do not attend rounds or do not engage during rounds. These are usually the same RT's that complain that they do not have protocols or that ventilator management is by physician order only. 

"Its your own fault, your NOT allowed to manage the ventilator"

Sunday, July 7, 2013

Why is this patient on mechanical ventilation TODAY?

Photo from:

It is very frustrating when I meet with the ICU staff Respiratory Therapist and ask why is this patient on the ventilator today and I get the following response “they had surgery”, “they coded”, “they had ventilatory failure”, “they have ARDS”, etc. Yet, these events happened hours, days, or even weeks ago, and they are not in the acute stages of their illness anymore.  There is a huge difference between initial indications for mechanical ventilation (MV) versus current goals for MV.