ANEclear Frequently Asked Questions and Answers
Design and Operation
Q: Who invented the ANEclear?
Joseph Orr, PhD and Dwayne Westenskow, PhD.
Q: Where or who did your clinical studies?
All clinical trials were conducted under the purview of the University of Utah’s IRB by Dr. Sakata and his team.
Q: What are the advantages of this device?
The ANEclear accelerates anesthetic gas elimination and restores patient control of the airway faster by increasing both cerebral blood flow and spontaneous respiration. The result is that patients move quickly through risky stage II, recover faster from anesthesia and are more alert after surgery. This means less time in the OR (reduced by 5-11 minutes), shorter PACU stays (shorter by ~30 minutes per patient), potential for better pain management, improved scheduling/utilization and lower costs for hospitals/surgery centers.
Q: Why do I need this device? I can already titrate my anesthetic and predict when the surgeon is going to be done.
During cases when tapering of anesthetic is not possible (abruptly ending case) or is not safe (patient should not move until completely finished), the ANEclear increases respiratory drive, reduces variability in emergence time and speeds emergence by up to 60%. In addition, the device may possibly complement the common practice of tapering the anesthetic at the end of the case in order to facilitate emergence.
Q: Which anesthetics work with this device?
Isoflurane, sevoflurane and desflurane are absorbed with this device.
Q: Does the ANEclear work with halothane?
There is no physical reason why the ANEclear would not work with halothane. However, it has not been tested with halothane and therefore its performance with respect to this anesthetic is unknown.
Q: How is nitrous oxide eliminated by this device?
Nitrous oxide is not absorbed and therefore not eliminated by the ANEclear. Nitrous oxide is eliminated when tidal volume exceeds the rebreathing dead space and the high fresh gas flow flushes it from the breathing circuit. Although nitrous oxide is not trapped by the absorber, its elimination from the brain can be accelerated by hypercapnic hyperventilation.
Q: Is there a different device for differently sized patients or cases of variable length?
The ANEclear can be used for all patients and all cases where the patient can be ventilated at higher than normal minute volumes (tidal volumes of at least 500 ml and increased respiratory rate) and where they can tolerate slightly increased airway resistance (up to 1.8 cm H2O at 30 L/min).
Q: Can I use the device with the absorber only and not the rebreathing loop?
No. If the device was to be used with the anesthetic absorber only and not the rebreathing loop, the inspired anesthetic would be eliminated, but the CO2 would fall in response to hyperventilation. This would lead to delayed anesthetic clearance from the central nervous system.
Q: On what types of patients should I not use this device?
This device should not be used with patients in whom hyperventilation by either increased tidal volume or rate would be contraindicated, or in those patients who would not tolerate increases in arterial CO2.
Q: How much does the ANEclear weigh?
180 grams (6 ounces).
Q: How much extra dead space does the ANEclear add to my breathing circuit when not activated?
Q: What is the total dead space of the ANEclear when the device is activated with the rebreathing loop collapsed?
Q: How large is the dead space of the fully extended rebreathing loop?
Q: What are the main risks associated with this device?
If the tidal volume is not greater than 500 mls when the device is activated, hypoxia may occur (although unlikely) because the effective dead space volume exceeds the tidal volume. If the device is prematurely activated during the case, the patient may emerge during the case.
Q: Will the ANEclear function properly if the capnometer/gas analyzer line is placed between the ANEclear and the anesthesia machine instead of between the patient and the ANEclear?
Yes. If tidal volumes are greater than 500 ml and the minute ventilation is at least doubled, the ANEclear will continue to function properly to facilitate emergence from volatile anesthetics.
Q: What happens if the capnometer/gas analyzer line is placed between the ANEclear and the anesthesia machine instead of between the patient and the ANEclear?
The gas readings will not reflect the individual gas concentrations that the patient is actually inhaling or exhaling, therefore Anecare does not advocate using the ANEclear in this configuration.
Q: Will the ANEclear work with all anesthesia machines and monitors?
The ANEclear will work with all machines and monitors if a 500 ml tidal volume (minimum) can be delivered and the emergence minute ventilation can be at least double that of the maintenance minute ventilation.
Q: Does the ANEclear work with the Draeger Apollo anesthesia machine?
Yes. However, the Apollo has difficulty discerning the difference between inhalation and exhalation while CO2 is being rebreathed when the ANEclear is active. The Apollo requires the fraction of inspired CO2 to be zero in order to determine that the patient is in inspiration. When the ANEclear is active, the fraction of inspired CO2 is not zero since the patient is actively rebreathing CO2. This may cause the machine to display oscillating values of inspired and expired oxygen and anesthetic agent. In addition, the Apollo may cease to display values of end tidal or fraction of inspired CO2.
Q: How should clinicians best use the ANEclear with the Draeger Apollo machines?
The ANEclear may be used with the Apollo as with any other machine. At emergence, ensure tidal volumes are at least 500 ml and that the minute ventilation is at least double the maintenance minute ventilation. To ensure proper monitoring of CO2 values the clinician must disable the CO2 alarm while the ANEclear is activated. During the short period of time that it takes for the patient to emerge from volatile anesthesia increased vigilance should be given to the CO2 levels as indicated in the ANEclear instruction for use. Note that when oxygen and anesthetic values begin to oscillate, the lower oxygen value displayed is the end tidal value and the higher oxygen value is the inspired value. Conversely, the lower of the anesthetic values (most likely zero) is the inspired anesthetic value and the higher anesthetic value is the end tidal value. As long as any of the oxygen values stays above 35%, the patient should maintain good oxygenation.
Q: Does it matter whether the breathing circuit filter is placed between the patient and the ANEclear, or the ANEclear and the breathing circuit “Y” connector?
Location of a filter has a minimal effect on the performance of the ANEclear. If the filter includes a heat/moisture exchanger (HME), then performance of the HME is improved if it is closer to the patient. The ANEclear most likely would perform better if the HME is placed between it and the patient. The reason for this is that the water vapor associated with each breath the patient exhales could potentially occupy surface area on the charcoal that could otherwise be occupied by molecules of anesthetic.
Q: Is the ANEclear anesthetic agent specific?
No. The ANEclear shortens emergence time for isoflurane, sevoflurane and desflurane.
Q: Are you planning to conduct additional clinical trials?
Yes. We plan to conduct investigator sponsored trials.
Q: May I use the ANEclear on multiple patients?
No. The ANEclear is a single-use, disposable product. The anesthetic absorbent in the ANEclear holds a finite amount of anesthetic vapor. If the ANEclear is reused, and the absorbent is already saturated, then performance will be unpredictable.
Q: What is the amount of anesthetic, case duration and patient weight that the ANEclear will accommodate?
The ANEclear anesthetic absorption filter has the capacity to absorb the anesthetic from a 150 Kg patient where 6% of desflurane is delivered for up to eight hours.
Q: What impact does my use of nitrous oxide have on the performance of the ANEclear.
Nitrous oxide is not absorbed by the ANEclear. The presence of nitrous oxide does not change the effectiveness with which the ANEclear absorbs volatile anesthetics. For rapid emergence following nitrous oxide anesthesia, nitrous oxide flows should be discontinued and fresh gas (100% oxygen) flows increased as early as possible prior to activation of the ANEclear.
Q: Does rebreathing increase the risk of desaturation?
When the rebreathing loop is fully extended tidal volumes should be above 500 ml to prevent desaturation. Because significant mixing occurs along the edges of the corrugated rebreathing loop, sufficient fresh oxygen mixes with the expired (rebreathed) tidal volume to provide adequate oxygenation.
Q: Does this device increase the work of breathing in a spontaneous breathing patient?
Since the device adds 1.8 cm H20 at 30 L/min of airway resistance to the breathing circuit, it does increase the work of breathing in the spontaneously-breathing patient. The added work of breathing is comparable to adding an additional large-diameter bacterial filter to the breathing circuit. The ANEclear is typically a very small percentage of the total circuit resistance. The work of breathing can be reduced in the spontaneously breathing patient by the use of pressure support or synchronous intermittent mandatory ventilation.
Q: Will the blood pH of the patient decrease with increased carbon dioxide concentration?
Yes. pH is simply a measure of the hydrogen ion concentration. This hydrogen ion concentration is a measure of acidity. An increased hydrogen ion concentration and therefore lower pH means greater acidity. Increased CO2 increases the hydrogen ion concentration in the blood and therefore the acidity.
Q: Is there a risk of clinically significant respiratory acidosis?
Rebreathing in the absence of an adequate increase in minute ventilation can cause the arterial CO2 concentration to rise. The rise in PaCO2 would cause the pH to fall, resulting in respiratory acidosis. As long as there is an adequate increase in minute ventilation, there is not a risk of clinically significant respiratory acidosis.
Q: Does the ANEclear work with a hypothermic patient?
Hypothermia can be defined for any patient in which the core body temperature drops below 36C. Beyond that, hypothermia is defined into three broad classes. Mild hypothermia would be a core body temperature between 35.5-35.9C. Moderate hypothermia would be a core body temperature between 35-35.4C. Severe hypothermia would be a core body temperature <35C. So, in answer to the question, for patients who are hypothermic (<36C), the ANEclear has been shown to speed emergence. It should be noted that decreases in core body temperature do increase the time it takes for patients to emerge from anesthesia. Studies have not been done to evaluate the impact the ANEclear has on decreasing emergence time with respect to hypothermic patients.
Q: Do you have a computer simulation of the ANEclear?
Yes. We have modeled the performance of the ANEclear based on our clinical trial data. For more information on the model, please contact Anecare.
Q: Can I activate and deactivate the device?
Yes. The device can be activated and deactivated. However, for safety reasons deactivation does not result in a 100% deactivated state.
Q: When should I put the device in line?
The ANEclear may be placed in the breathing circuit at any time prior to emergence. The ANEclear has an activation switch that engages the rebreathing loop and the agent absorber.
Q: When should I extend the rebreathing loop?
You can extend the rebreathing loop anytime prior to emergence. However, we recommend extending the loop prior to placing the ANEclear in the breathing circuit to minimize the risk of inadvertently dislodging the endotracheal tube. The ANEclear is changed from bypass mode to active mode by a flip of the switch.
Q: To what length should I extend the rebreathing loop?
If the patient can safely tolerate hyperventilation—with tidal volumes in excess of 500 mls—extend the loop completely. If the patient’s end tidal CO2 rises above 55 mm Hg, increase ventilation, if possible. If increased ventilation is contra-indicated, compress the rebreathing loop.
Q: When do I activate the device?
Activate the deviceimmediately preceding emergence.
Q: Which is more important, hyperventilation or hypercapnia?
Clinical studies have shown that hyperventilation or hypercapnia alone fails to speed emergence and that optimal performance is achieved when both are used together.
Q: Is it better to increase the tidal volume or respiratory rate?
Hyperventilation results from increases in both tidal volume and respiratory rate. The best combination depends on the patient’s pulmonary physiology and the presence of restrictive lung disease, chronic obstructive pulmonary disease, etc. The only caveat is that the tidal volume must be greater than 500 ml when the rebreathing loop is fully extended. If there is difficulty in achieving hyperventilation, check the inspiratory flow limit and inspiratory pressure limit settings on the ventilator. Tidal volumes significantly greater than 760 mls tend to slow the rate of rise in end tidal CO2, because part of the exhaled CO2 moves out of the rebreathing loop and into the breathing circuit. If the end tidal CO2 does not rise rapidly, consider reducing the tidal volume and increasing the respiratory rate.
Q: Does the ANEclear work if I use low-flow anesthesia?
Yes. The fresh gas flow rate during the case has no bearing on emergence. Emergence is separate from anesthesia maintenance. Emergence is a time that low-flow of fresh gases are not used and may actually be counterproductive to the goal of expeditious emergence from anesthesia. It should also be noted that when nitrous oxide is used, the fresh gas flow should be increased during emergence to enhance the washout of nitrous oxide.
Q: Does the ANEclear require the use of a monitoring device of any kind?
A capnometer is required and an anesthesia gas analyzer is recommended. The sampling port of the capnometer should always be connected between the patient and the ANEclear.
Q: If I use nitrous oxide during a case in which I am intending to use the ANEclear, when should I shut off the nitrous oxide and why?
Rebreathing slows the rate at which nitrous oxide is eliminated. It is better to turn off the nitrous oxide several minutes before the case ends so it can be eliminated before the ANEclear is activated and rebreathing begins. If the patient was on nitrous oxide and needs to be kept at a deep level of anesthesia right up until the end of the case, use increased levels of volatile agent instead of nitrous oxide.
Q: Can I use the device with just the rebreathing loop and not the absorber?
No. Use in this manner would allow elevated CO2 levels due to rebreathing, but would also lead to rebreathed anesthetic gases, thereby delaying emergence.
Q: What minute volume value should I use?
We recommend at least doubling the maintenance minute volume. For more details, see Hyperventilation Strategies For Optimized ANEclear Performance.
Q: What happens if the tidal volume drops below 500 ml?
It is possible that if the tidal volume drops below 500 ml that an individual may possibly be rebreathing too much and may start to have lower oxygen levels because of lower oxygen supply. CO2 may begin to increase too much and the oxygen level may begin to decrease. Excessive hypercapnia and/or hypoxia may result. If a patient persists with tidal volumes less than 500 ml, it may be possible to continue the use of the ANEclear. However, the clinician should be attentive to the fraction of inspired oxygen. This value should not be allowed to drop below 35%.
Q: Can I use the ANEclear with a spontaneously breathing patient?
The ANEclear provides a safer and faster emergence from inhaled anesthetics in spontaneously breathing patients. With such patients, an activated ANEclear uses rebreathing of CO2 to raise the patient's PaCO2. This respiratory stimulant increases the patient's spontaneous tidal volume and respiratory rate, which speeds the rate of removal of the inhaled anesthetic from the lungs. The respiratory stimulant also helps the patient breathe through the LMA, endotracheal tube, or face mask, the airway filter, the ANEclear and the anesthesia circuit. When the ANEclear is used in spontaneously breathing patients, respiratory monitoring is needed to insure that the patient breathes with a tidal volume of at least 500 ml. This provides adequate oxygenation during rebreathing. If the fraction of inspired oxygen drops below 35% or the oxygen saturation drops below 90%, the ANEclear should be deactivated.
Q: How do I use the ANEclear with a spontaneously breathing patient?
Extend the rebreathing loop and activate the ANEclear. The increased CO2 will increase the respiratory drive and will increase minute ventilation. If necessary, you can increase minute ventilation by hand bagging or using a ventilator in a patient triggered ventilation mode.
Q: Will the ANEclear work with a Laryngeal Mask Airway (LMA)?
Yes, the ANEclear will help speed emergence while breathing with a LMA. Most patients breathe spontaneously while using the LMA. While using the ANEclear with a spontaneously breathing patient, the clinician should be attentive to the fraction of inspired oxygen. This value should not be allowed to drop below 35%. With the rebreathing of CO2 and the elimination of anesthetic agent, the patient should increase their own minute ventilation. The amount of increase in minute ventilation is unknown given patient variability and the amount, as well as the type, of medications used. It should be recognized that LMA’s are less stimulating than an endotracheal tube and elimination of anesthetic is dependent on how much the patient breathes on their own. Therefore, time until emergence may be a bit longer.
Q: How do I optimize ANEclear performance with the LMA?
Given that most patients breathe spontaneously when a LMA is used, emergence optimization with a ANEclear means that minute ventilation should be optimized or increased. In a spontaneously breathing patient, the best way to accomplish this is with pressure support ventilation.
Q: What is the correct procedure if a patient begins to fight the ventilator at emergence?
Fighting the ventilator is a common occurrence when patients come out of anesthesia. As patients emerge from anesthesia and start to breathe on their own, the endotracheal tube and the ventilator’s controlled breaths irritate the patient. Fighting the ventilator is non-productive and may have safety implications because it limits tidal volumes and also increases airway pressures. This may be detrimental to the lungs. When this occurs, the clinician should respond as they normally would at the end of the case. Most likely this would entail turning off the ventilator. The ANEclear may remain active. However, the clinician should be encouraged to place the patient on synchronous intermittent mandatory ventilation (SIMV) or pressure support (PS), if available. This will allow the machine to help augment spontaneous breaths with greater tidal volumes or possibly even “kick-in” breaths if the patient is not making an effort to breathe after the ventilator is taken out of control mode. If neither of these modes is available, the patient may remain off the ventilator with the ANEclear activated so long as the fraction of inspired oxygen remains above 35% and oxygen saturations remain above 90%.
Q: When I use the ANEclear to speed emergence are my patients more likely to become re-anesthetized due to leaching of anesthetics from the muscle and fat?
No. Upon cessation of anesthesia, anesthetic in muscle and fat depots returns to the lungs in the venous blood. If cleared at the lungs, the anesthetic will not recirculate to the brain. Considering isoflurane (the most soluble agent) as the worst case, anesthetic will not recirculate to the brain as long as ventilation is greater than 1.7 L/min. Lower rates of ventilation will be adequate for shorter cases and for cases where sevoflurane or desflurane are used.
Q: How is emergence from the ANEclear affected by injection of fentanyl and sufentanil prior to emergence from anesthesia?
Injection of opioids, such as fentanyl and sufentanil, lower the amount of vapor needed to maintain anesthesia (MAC reduction). Opioids also lower the threshold concentrations at which patients emerge from inhaled anesthetic and can therefore delay emergence. Note that use of the ANEclear can not compensate for delayed awakening caused by injection of opioids given during the period immediately prior to intended emergence.
Q: Are there intravenous anti-nausea medications (antiemetics) that can slow emergence from anesthesia?
Yes. There are certain antiemetics that can slow emergence from anesthesia due to their concomitant sedating effects. These drugs include droperidol, prochlorperazine and scopolamine. Antiemetics such as commonly used dolasetron, ondansetron and dexamthasone do not generally cause sedation.
Q: When using the ANEclear, when should I extubate the patient?
Continue to use your best clinical judgment.
Q: What clinical benefits have other physicians seen when using the ANEclear?
Clinicians have experienced the benefit of keeping their patients deep under anesthesia until the very end of the case without losing the benefit of an increased drive to breathe and rapid emergence. They have noted the shortened (or lack of) stage II during emergence. Many clinicians have stated that their patients seem very alert after their anesthetic when the ANEclear is used. This alertness has been especially apparent after the use of isoflurane. Clinicians have also recognized that on longer cases, costs can be lowered by using isoflurane with the ANEclear.
Q: Is the ANEclear cleared by the FDA?
Yes, we have received FDA clearance to market the device in the United States.
Q: What FDA class is this device?
Class II with clinical data required.
Q: Is the ANEclear CE marked?
Q: Now that Anecare has obtained FDA clearance, when will you ship product to customers in the US?
The ANEclear is now available for immediate shipment to customers throughout the US.
Q: When do you expect the ANEclear to be available in Europe and Asia?
Anecare is developing distribution agreements for Europe and Asia and will announce those arrangements as soon as they are completed.
Q: How many devices come in a carton?
A standard carton contains 20 devices.
Q: Who will be my local representative?
Contact Anecare for information regarding your local representative.
Q: How has Anecare been financed?
Anecare is privately funded.
Q: How can I invest in Anecare?
Investment inquiries are handled by contacting our CEO Mike Slatter at 801.977.8877.
Q: Can I purchase standard breathing circuits with the device already built in?
Not at this time.
Q: Do you have contracts in place with the GPOs?
Not at this time.
Q: Does Anecare consider itself a competitor with any manufacturer or vendor of volatile anesthetics?