Latest posts by the anesthesia consultant (see all)
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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.
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.
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:
Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below: