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).
ecoFlow
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.
ISSUE 1: The Modeling Tool
a. I created the modeling tool in which savings are projected by changing efficiency by 30%. Obtaining increased efficiency by 30% can be difficult to achieve, it depends on baseline efficiency. If all the anesthesia providers in a department use low & minimal flow techniques you will not increase efficiency that much or at all.
b. The calculation is based on 100% compliance- This means all practitioners must perform minimal flow anesthesia. This equates to changing practice, not only for one person but for the entire staff.
c. Savings very from how many OR suites are in use & how many surgical days are in a year.
ISSUE 2: The Patient
a. Not every patient is a ideal for minimal flow anesthesia- Due to an ageing population, comorbidities, and more advance surgical procedures it may not be safe to administer minimal flow anesthesia, due to hypercapnia & hypoxia.
b. Patient size- This refers to the re-breathing quotient and its relation to efficiency.
Example-you have two patients one that is 60 kg & 80 kg (Ideal Body weight).
This would be a minimum minute ventilation requirement of 6 lpm for the 60 kg patient & 8 lpm for the 80 kg patient.
You drop the fresh gas flow to 1 lpm.
The 60 kg patient is re-breathing 83%
The 80 kg patient is re-breathing 87% (more efficient).
ISSUE 3: Agent
a. Sevoflurane- Even-though one can run Sevo under 2 lpm (not less than 1 lpm) for 2 MAC hours [2] , rarely anybody does it. Most providers run it 2 lpm, now efficiency/re-breathing is determined by patient's minute ventilation requirements (see above/patient size).
b. Desflurane- One can provide closed-system anesthesia by using Desflurane and greatly increasing efficiency. However, the cost of the agent per bottle is dramatically more then using Sevoflurane, which has led to some departments not using the agent.
Additionally, with using lower flows the soda lime is going to deplete quicker (see soda lime cost below).
c. User agreements- Agreements made by the agent manufacturer and pharmacy, can include single source, price based on usage, and the supply of the vaporizer. Contracts based on agent usage can be effected if a department becomes more efficient in anesthesia delivery.
Example 1- Contract provides the agent at a fixed price if you use X number of bottles per year. Say you decrease use by 1/2 bottles, most likely the price per bottle will now go up.
Example 2- The agent company provides the vaporizers for free for sole source agreement & usage agreement. If you decrease anesthetic agent usage you may have to purchase the vaporizers or face a price increase in agent cost.
ISSUE 4: The Cost of Soda Lime
As previously mentioned using minimal flow anesthesia techniques depletes the soda lime quicker. One has to balance the anesthetic agent cost savings versus the cost of soda lime.
Here is an example of soda lime prices [3]
| Sr no | Company name | Product | Prices |
| 1 | Draeger Medical | Draeger Drägersorb CLIC 800 Plus Disposable Absorber, 6/Cs | $173.52 |
| 2 | Draeger Medical | Draeger Draegersorb CLIC 800 Plus Disposable Absorber, 6/Cs | $165.99 |
| 3 | Draeger Medical | Draeger Draegersorb CLIC 800 Plus Disposable Absorber, 6/Cs | $165.99 |
| Sr no | Company name | Product | Prices |
| 1 | Draeger Medical | Drägersorb Free | $47.00 plus tax |
| Sr no | Company name | Product | Prices |
| 1 | Armstrong medical | Bubble-cans Amsorb plus | $25 USD |
| 2 | Armstrong medical | Bubble-cans Amsorb plus | $25 USD |
| Sr no | Company name | Product | Prices |
| 1 | GE HealthCare | MediSorb | $26 USD |
This phantom cost adds up.
In a 2011 ASA abstract, [4] authors presented that soda lime cost may off-set agent savings when using minimal flow anethesia techniques.
For a pharmacy/hospital to actually see significant cost savings from low flow techniques
It is imperative to have:
1. 100% anesthesia staff compliance in utilizing low flow techniques (which requires a change in practice).
2. Use primarily desflurane.
3. Have flexible agent usage agreements, that do not increase price for a decrease in overall usage.
4. Have reasonably priced soda lime agreements.
SAVING ANESTHETIC AGENT WITHOUT LOW FLOW OR MINIMAL FLOW TECHNIQUES
Vaporizer design- new injection vaporizers that only dose during the inspiratory phase [5].
Anesthetic Gas Reclamation
 |
| http://www.gasrecycler.com/ |
More at: http://www.gasrecycler.com/
Reference
[1]. Dr. James Philip "Gas Man" http://www.gasmanweb.com/about_us.html
[2]. Risk Information with Sevoflurane
http://www.baxter.com/healthcare_professionals/products/sevoflurane.html
[3]. Soda lime cost 2011 search links:
Do Increased Canister Costs Offset Decreased Sevoflurane Costs When Fresh Gas Flows are Reduced?