Tag total intravenous anesthesia

ROBOT ANESTHESIA II

THE ANESTHESIA CONSULTANT 3 Comments
THE ANESTHESIA CONSULTANT
THE ANESTHESIA CONSULTANT
Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
emailrjnov@yahoo.com
THE ANESTHESIA CONSULTANT
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Are anesthesiologists on the verge of being replaced by a new robot? In a word, “No.” The new device being discussed is the iControl-RP anesthesia robot.

THE iCONTROL-RP ANESTHESIA ROBOT

On May 15, 2015, the Washington Post published a story titled, “We Are Convinced the Machine Can Do Better Than Human Anesthesiologists.”

In recent years there have been significant advances in the automated delivery of the intravenous anesthetic drugs propofol and remifentanil. (Orliaguet GA, Feasibility of closed-loop titration of propofol and remifentanil guided by the bispectral monitor in pediatric and adolescent patients: a prospective randomized study, Anesthesiology 2015 Apr;122(4):759-67). Propofol is an ultra-short-acting hypnotic drug that causes sleep. Remifentanil is an ultra-short-acting narcotic that relieves pain. Administered together, these drugs induce what is referred to as Total Intravenous Anesthesia, or TIVA. Total Intravenous Anesthesia is a technique anesthesiologists use when they choose to avoid using inhaled gases such as sevoflurane and nitrous oxide. Anesthesiologists administer TIVA by adjusting the flow rates on two separate infusion pumps, one infusion pump containing each drug.

A closed-loop system is a machine that infuses these drugs automatically. These systems include several essential items: The first is a processed electroencephalogram (EEG) such as a bi-spectral monitor (BIS monitor) attached to the patient’s forehead which records a neurologic measure of how asleep the patient is. The BIS monitor calculates a score between 0 and 100 for the patient’s level of unconsciousness, with a score of 100 corresponding to wide awake and 0 corresponding to a flat EEG. A score of 40 – 60 is considered an optimal amount of anesthesia depth. The second and third essential items of a closed-loop automated system are two automated infusion pumps containing propofol and remifentanil. A computer controls the infusion rate of a higher or lower amount of these drugs, depending on whether the measured BIS score is higher or lower than the 40- 60 range.

Researchers in Canada have expanded this technology into a device they call the iControl-RP, which is in clinical trials at the University of British Columbia. The iControl-RP is a closed-loop system which makes its own decisions. The initials RP stand for the two drugs being titrated: remifentanil and propofol. In addition to monitoring the patient’s EEG level of consciousness (via a BIS monitor device called NeuroSENSE), this new device monitors traditional vital signs such as blood oxygen levels, heart rate, respiratory rate, and blood pressure, to determine how much anesthesia to deliver.

Per published information on their research protocol, the iControl-RP allows either remifentanil or propofol to be operated in any of three modes: (1) closed-loop control based on feedback from the EEG as measured by the NeuroSENSE; (2) target-controlled infusion (TCI), based on previously-described pharmacokinetic and pharmacodynamic models; and (3) conventional manual infusion, which requires a weight-based dose setting. (Reference: Closed-loop Control of Anesthesia: Controlled Delivery of Remifentanil and Propofol Dates, Status, Enrollment Verified by: Fraser Health, August 2014, First Received: January 15, 2013, Last Updated: March 5, 2015, Phase: N/A, Start Date: February 2013, Overall Status: Recruiting, Estimated Enrollment: 150).

In Phase 1 of the iControl-RP testing involving 50 study subjects, propofol will be administered in closed-loop mode and a remifentanil infusion will be administered based on a target-controlled infusion. In phase 2 involving 100 study subjects, both propofol and remifentanil will be administered in closed-loop mode. The investigators aim to demonstrate that closed-loop control of anesthesia and analgesia based on EEG feedback is clinically feasible.

In both phases, an anesthesiologist will monitor the patient as per routine practice and have the ability to modify the anesthetic or analgesic drugs being administered. That is, he or she will be able to adjust the target depth of hypnosis, adjust the target effect site concentration for remifentanil, immediately switch to manual control of either infusion, administer a bolus dose, or immediately stop the infusion of either drug. iControl-RP is connected to the NeuroSENSE EEG monitor, the two infusion pumps for separately controlled propofol and remifentanil administration, and the operating room patient vital signs monitor. A user interface allows the anesthesiologist to set the target EEG depth level, switch between modes of operation (manual, target-controlled infusion, or closed-loop), and set manual infusion rates or target effect-site concentrations for either drug as required.

Per the article in the Washington Post. (Todd C. Frankel, Washington Post, May 15, 2015), one of the machine’s co-developers Mark Ansermino, MD said, “We are convinced the machine can do better than human anesthesiologists.” The iControl-RP has been used to induce deep sedation in adults and children undergoing general surgery. The device had been used on 250 patients so far.

Why is this robotic device only a small step toward replacing anesthesiologists?

A critical realization is that anesthetizing patients requires far more skill than merely titrating two drug levels. Every patient requires (1) preoperative assessment of all medical problems from the history, physical exam, and laboratory evaluation of each individual patient, so that the anesthesiologist can plan and prescribe the appropriate anesthesia type; (2) placement of an intravenous line through which the TIVA drugs may be administered; (3) mask ventilation of an unconscious patient (in most cases), followed by placement of an airway tube to control the delivery of oxygen and ventilation in and out of the patient’s lungs; (4) observation of all vital monitors during surgery, with the aim of directing the diagnosis and treatment of any complication that occurs as a result of anesthesia or the surgical procedure; (5) removal of the airway tube at the conclusion of most surgeries, and (6) the diagnosis and treatment of any complication in the newly awake patient following the anesthetic.

In the future, closed-loop titration of drugs may lessen an anesthesiologist’s workload and free him or her for other activities. In the distant future, closed-loop titration of drugs may free a solitary anesthesiologist to initiate and monitor multiple anesthetics simultaneously from a control booth via multiple video screens and interface displays. But the handling of all tasks (1) – (6) by an automated robotic device is still the stuff of science fiction. The Washington Post article said an early role for the machine could be in war zones or remote areas where an anesthesiologist is unavailable. One could conjecture that a closed-loop anesthesia system may be used to facilitate surgery in outer space some day as well.

In either case, an anesthesiologist or some other highly-trained medical professional will still be required on site to achieve tasks (1) – (6).

The iControl-RP has not been approved by the U.S. Food and Drug Administration.

The iControl-RP team has struggled to find a corporate backer for its project. Dr. Ansermino, the anesthesiologist inventor in Vancouver, told the Washington Post, “Most big companies view this as too risky,” but he believed a device like this was inevitable. “I think eventually this will happen,” Ansermino told the Washington Post, “whether we like it or not.”

That may be, but I suspect companies are risk averse regarding the iControl-RP because investment is guided by analysts and physicians who must consider the practical applications and risks of any new medical device. The issues of leaving (1) – (6) up to a robotic device are impractical at best, and dangerous to the patient at worse.

The most popular posts for laypeople on The Anesthesia Consultant include:

How Long Will It Take To Wake Up From General Anesthesia?

Why Did Take Me So Long To Wake From General Anesthesia?

Will I Have a Breathing Tube During Anesthesia?

What Are the Common Anesthesia Medications?

How Safe is Anesthesia in the 21st Century?

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What Are the Anesthesia Risks For Children?

The most popular posts for anesthesia professionals on The Anesthesia Consultant  include:

10 Trends for the Future of Anesthesia

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Advice For Passing the Anesthesia Oral Board Exams

What Personal Characteristics are Necessary to Become a Successful Anesthesiologist?

Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below:  

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PITFALLS OF TOTAL INTRAVENOUS ANESTHESIA

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THE ANESTHESIA CONSULTANT
THE ANESTHESIA CONSULTANT
Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
emailrjnov@yahoo.com
THE ANESTHESIA CONSULTANT
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Clinical Case:  You are doing Total Intravenous Anesthesia  (TIVA) for a laparoscopic cholecystectomy on a healthy 40 year old woman.  Midway through the surgery, the patient’s heart rate suddenly climbs to 160, and the blood pressure climbs to 190/110.  What do you do?

Discussion:   Your own heart rate hits 170.  You check the ABC’s of Airway, Breathing, and Circulation, and note that the endotracheal tube is still in the trachea, and both lungs are being ventilated with clear breath sounds.  The oxygen saturation is 100%.  You check the anesthetic drugs, and confirm that  both the propofol and remifentanil pumps are running properly.  A check of the IV shows the Lactated Ringers is not dripping, despite the fact that the roller clamp is wide open.  The IV is in the left arm, which is positioned abducted at 90 degrees.  You inspect the IV insertion site and find that the IV has infiltrated.

You turn on sevoflurane at 4% and nitrous oxide at 70%, and scramble to restart an IV in the outstretched arm.  In  minutes you have a new IV, and you give a bolus of 140 mg of propofol.  The heart rate decreases to 80 beats per minute, and the blood pressure decreases to 110/50.  You decrease the sevoflurane to 1.5 %, discontinue the nitrous oxide, and reconnect the TIVA infusions of propofol and remifentanil.

Don’t believe it could happen?   Tong described intraoperative awareness  during TIVA for  laparoscopy, due to physician error in  improperly positioning the latch of the movable lever in the propofol syringe driver at the top of the plunger (Can J Anaesth. 1997 Jan;44(1):4-8.), so that no propofol was infusing.   Several series of TIVA cases document incidence of awareness ranging from 2 patients out of 1000,  or .2%  (Nordstrom O, Acta Anaesthesiol Scand. 1997 Sep;41(8):978-84.), to 8 patients out of 90, or 8.8% (Miller DR, Can J Anaesth. 1996 Sep;43(9):946-53.)  Any technical error, such as the pump(s) not being turned on, the pump(s) malfunctioning, the syringes being empty, stopcocks being closed rather than open, or the IV infiltrating, can lead to failure of TIVA technique.  In addition, inadequate narcotic or propofol infusion rates can lead to inadequate anesthetic depth.  When coupled with neuromuscular paralysis, the most prominent signs of inadequate anesthetic depth will be tachycardia and hypertension.

TIVA is a viable option for general anesthesia because of the availability of ultra-short acting narcotics such as remifentanil and hypnotics such as propofol.  Learning this sort of technique is part of a complete residency experience.  There is less gas pollution when TIVA is used.  If you ever need to give an anesthetic in outer space or at zero gravity, your experience with TIVA will be invaluable.

Will you find much TIVA practiced in the private practice world of anesthesia?  My observation is that most private cases involving general anesthesia with muscle relaxation include inhalational anesthetic.  Propofol infusions are often included, and at times so are remifentanil infusions.  But to insure lack of awareness,  the potent anesthetic vapors  of sevoflurane, desflurane, or isoflurane are still the mainstays of awareness prevention when muscle relaxants are used.  The KISS Principle, or Keep It Simple Stupid, dictates that it is easier to turn on one vaporizer than to fidget with multiple syringe pumps.  (The vaporizer needs to include liquid anesthetic, and it needs to be turned on to an adequate concentration, or awareness can still occur.)

Some may suggest that all anesthetics be monitored by  continuous bispectral index (BIS) monitors to insure lack of awareness.  A case of awareness despite BIS monitoring has been published, (Kurehara K, Masui 2001 Aug;50(8):886-7.) in which a 77 year old patient had  awareness during a thoracotomy  despite BIS scores that indicated adequate hypnotic depth.  A recent prospective study (Ekman A, Acta Anaesthiol Scand 2004 Jan; 48(1):20-6.) documented explicit recall in 2 of 4945 patients (.04%) in general anesthetics requiring  muscle relaxation, using BIS monitoring.  This was significantly lower than their historical control rate of .18% of explicit recall in paralyzed patients without BIS monitoring.  But note than that even with BIS monitoring, the incidence of recall is not zero.  Whatever technique or monitors are employed, the skill and vigilance of the attending anesthesiologist will be  of highest  importance in maintaining adequate anesthesia drug administration.

Patients expect their anesthesiologist to keep them safe, to keep them asleep during the surgery, and to wake them up after the surgery.  Patients ask me about the risk of intra-operative awareness dozens of times per year.  The amount of times I want this to occur for my patients, or for yours, is zero.  Diversify your anesthetic regimen.  Don’t bet the ranch on your IV.

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Published in September 2017:  The second edition of THE DOCTOR AND MR. DYLAN, Dr. Novak’s debut novel, a medical-legal mystery which blends the science and practice of anesthesiology with unforgettable characters, a page-turning plot, and the legacy of Nobel Prize winner Bob Dylan.

KIRKUS REVIEW

In this debut thriller, tragedies strike an anesthesiologist as he tries to start a new life with his son.

Dr. Nico Antone, an anesthesiologist at Stanford University, is married to Alexandra, a high-powered real estate agent obsessed with money. Their son, Johnny, an 11th-grader with immense potential, struggles to get the grades he’ll need to attend an Ivy League college. After a screaming match with Alexandra, Nico moves himself and Johnny from Palo Alto, California, to his frozen childhood home of Hibbing, Minnesota. The move should help Johnny improve his grades and thus seem more attractive to universities, but Nico loves the freedom from his wife, too. Hibbing also happens to be the hometown of music icon Bob Dylan. Joining the hospital staff, Nico runs afoul of a grouchy nurse anesthetist calling himself Bobby Dylan, who plays Dylan songs twice a week in a bar called Heaven’s Door. As Nico and Johnny settle in, their lives turn around; they even start dating the gorgeous mother/daughter pair of Lena and Echo Johnson. However, when Johnny accidentally impregnates Echo, the lives of the Hibbing transplants start to implode. In true page-turner fashion, first-time novelist Novak gets started by killing soulless Alexandra, which accelerates the downfall of his underdog protagonist now accused of murder. Dialogue is pitch-perfect, and the insults hurled between Nico and his wife are as hilarious as they are hurtful: “Are you my husband, Nico? Or my dependent?” The author’s medical expertise proves central to the plot, and there are a few grisly moments, as when “dark blood percolated” from a patient’s nostrils “like coffee grounds.” Bob Dylan details add quirkiness to what might otherwise be a chilly revenge tale; we’re told, for instance, that Dylan taught “every singer with a less-than-perfect voice…how to sneer and twist off syllables.” Courtroom scenes toward the end crackle with energy, though one scene involving a snowmobile ties up a certain plot thread too neatly. By the end, Nico has rolled with a great many punches.

Nuanced characterization and crafty details help this debut soar.

Click on the image below to reach the Amazon link to The Doctor and Mr. Dylan:

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Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below:  

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