HYPOTENSION OF 85/45 FOLLOWING THE INDUCTION OF ANESTHESIA: WHAT DO YOU DO?

CLINICAL CASE: You’re scheduled to anesthetize a healthy 55-year-old female for an appendectomy. Her blood pressure is 150/90 on admission. In the operating room, you induce anesthesia with your standard recipe of 2 mg of midazolam, 100 mcg of fentanyl, 200 mg of propofol, and 40 mg of rocuronium, and intubate the trachea. Five minutes after induction and 15-30 minutes before the surgical incision will occur, her blood pressure drops to 85/45. Is this a problem? What will you do? What level of hypotension is acceptable to you?

DISCUSSION: During surgery, anesthesiologists balance their administration of drugs to the level of surgical stimulation the patient is experiencing. The placement of an endotracheal tube is an intense stimulus to an awake patient, but only a moderate stimulus to an anesthetized patient. After the placement of an endotracheal tube, a lag time of fifteen minutes to thirty minutes or more occurs prior to surgical incision. During this interval, the blood pressure sometimes sags.

Let’s look at the anesthesia literature to learn what has been described about this problem.

David Reich, et al of Mt. Sinai Hospital in New York queried the computerized anesthesia records of 4,096 patients undergoing general anesthesia and analyzed the incidence of hypotension in the period immediately after induction. (Predictors of hypotension after induction of general anesthesia Anesth Analg. 2005 Sep;101(3):622-8). The median blood pressure (MAP) was determined before anesthesia induction, during the first 5 minutes after induction, and also the period from 5-10 minutes after induction. Hypotension was defined as either (1) a mean arterial blood pressure (MAP) decrease of >40% and MAP

Statistically significant predictors of hypotension after anesthetic induction included: ASA III-V, baseline MAP

Dr. Reich wrote, “association with mortality alone was not reported in the manuscript but was nearly statistically significant (P = 0.066). The majority of our colleagues apparently believe that transient hypotension is inconsequential to outcomes. Although limited by the problems associated with retrospective studies, the results of our study provide preliminary evidence that runs counter to the prevailing wisdom regarding transient severe hypotension during general anesthesia.”

What level of hypotension is unsafe for patients?

The effects of hypotension in nonsurgical subjects was studied in 1954 (Finnerty, FA, Cerebral Hemodynamics during Cerebral Ischemia Induced by Acute Hypotension1 Clin Invest. 1954 Sep; 33(9): 1227–1232). Young and old experimental subjects were subjected to increasing degrees of hypotension until clinical signs of cerebral ischemia developed. Hypotension was induced by intravenous administration of the anti-hypertensive medication hexamethonium. The authors discovered a linear relation between pre-hypotensive blood pressure and the level of induced hypotension that produced clinical signs of cerebral ischemia such as yawning, sighing, staring, confusion, inability to concentrate, inability to perform simple commands, nausea, dizziness, and involuntary body movements. Their data revealed that the safe level of hypotension was no lower than about 2/3 of the resting blood pressure before inducing hypotension. At 2/3 of their pre-procedure MAP, patients reached a threshold of clinical cerebral ischemia, with onset of yawning, sighing, staring, confusion, inability to concentrate, and inability to carry out simple commands. Because these studies were done on unanesthetized humans, it’s impossible to equate the data to patients with surgical anesthesia. Surgical patients have a different etiology for their hypotension, as well as reduced cerebral oxygen consumption from general anesthetic drugs. This explains why most surgical patients fail to manifest any cerebral damage resulting from episodes of hypotension occasionally following the induction of anesthesia.

The problem of hypotension and refractory hypotension following induction of anesthesia is currently being studied in an ongoing clinical trial at the University of Iowa. (ClinicalTrials.gov identifier: NCT02416024, contact Kenichi Ueda, MD, kenichi-ueda@uiowa.edu). Induction agents in this study will include 1.5 mg/kg propofol, 2 mcg/kg fentanyl, 100 mg lidocaine, and 0.6 mg/kg rocuronium. Inhaled anesthetic will be sevoflurane at 0.5 MAC with 5L/min of 100% oxygen starting at mask ventilation till 10 minutes after tracheal intubation. Blood pressure will be measured by a brachial cuff prior to induction and every minute after intubation for 10 minutes. If the systolic pressure drops below 90 mmHg or more than 25% from baseline, the patient will be classified in the study as “Hypotensive.” Conversely, if the patient’s systolic blood pressure does not drop below 90 mmHg more than 25% from baseline within 10 minutes of intubation, the patient will be classified as “Not Hypotensive.” In attempt to bring systolic blood pressure up to above 90 mmHg or more than 25% from baseline in “hypotensive” patients, the anesthetic provider will use 100 mcg of phenylephrine (or 5 mg ephedrine if heart rate < 50 bpm) within 10 minutes of intubation. If over 200 mcg of phenylephrine (or 10 mg ephedrine) has been used without a return of the systolic brachial blood pressure >90 mmHg or more than 25% from baseline, the patient will be classified in the study as “Refractory Hypotensive.” Look for the results of this trial to be published in years to come.

Based on the data reviewed in this column, it seems advisable to maintain a patient’s mean arterial pressure at or above a level of 2/3 of their baseline pressure. What if the patient’s baseline blood pressure in their outpatient clinic notes is 120/80 (MAP=93) yet in the pre-operative room on admission to surgery their blood pressure is 150/90 (MAP=110)? This is not an uncommon occurrence, as blood pressure often spikes secondary to the inevitable anxiety which accompanies a pending surgery. Is the anesthesia provider compelled to maintain the blood pressure at 2/3 of 110 = 73 after induction, or compelled to maintain the blood pressure at 2/3 of 93 = 62 after induction? I can find no specific data to answer this question. In my experience, after the administration of 2 mg of intravenous midazolam the hypertensive 150/90 often decreases to the 120/80 (MAP=93) range. With this MAP = 93 value as the baseline blood pressure, 2/3 X 93 = 62 would be the lowest level of MAP I’d feel comfortable with. We’re trained to treat post-induction hypotension with a vasopressor. Typically phenylephrine 100 mcg will increase the pressure to its preinduction level. Some patients require more than one dose of phenylephrine.

Let’s return to the management of your Clinical Case above.

  1. You choose to administer a dose of phenylephrine 100 mcg IV, and the blood pressure returns to 110/70. You maintain general anesthesia depth with the inhaled anesthetic sevoflurane at 0.5 MAC with 5L/min of 100% oxygen.
  2. Five minutes later the blood pressure drops to 85/45 again, and you repeat a dose of phenylephrine 100 mcg IV.
  3. When the surgery begins, the blood pressure increases to 150/90, and you treat by increasing anesthesia depth.
  4. Note that per the Reich data above, the incidence of hypotension increased with higher doses of fentanyl at induction (5-5.0 mcg/kg fentanyl vs. 0-1.5 mcg/kg fentanyl). I’ve found that the lower dose range of fentanyl, specifically zero fentanyl at induction, works very well for many patients. Incremental doses of propofol alone blunt the transient hypertensive response to laryngoscopy and intubation, and the lack of fentanyl leads to less hypotension in the ten minutes post-intubation. Appropriate levels of narcotics are then titrated in when surgery commences and the surgical stimulus increases. Also per Reich’s data, for patients age 50 or older who are ASA III-V, or for patients who present with a baseline pre-operative MAP

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Introducing …,  THE DOCTOR AND MR. DYLAN, Dr. Novak’s debut novel, a legal mystery. Publication date September 9, 2014 by Pegasus Books.

On October 2, 2014 THE DOCTOR AND MR. DYLAN became the world’s  #1 bestselling anesthesia Kindle book on Amazon.com.

The first four chapters are available for free at Amazon. Read them and you’ll be hooked! To reach the Amazon webpage, click on the book image below:

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Stanford professor Dr. Nico Antone leaves the wife he hates and the job he loves to return to Hibbing, Minnesota where he spent his childhood. He believes his son’s best chance to get accepted into a prestigious college is to graduate at the top of his class in this remote Midwestern town. His son becomes a small town hero and academic star, while Dr. Antone befriends Bobby Dylan, a deranged anesthetist who renamed and reinvented himself as a younger version of the iconic rock legend who grew up in Hibbing. An operating room death rocks their world, and Dr. Antone’s family and his relationship to Mr. Dylan are forever changed.

Equal parts legal thriller and medical thriller, The Doctor and Mr. Dylan examines the dark side of relationships between a doctor and his wife, a father and his son, and a man and his best friend. Set in a rural Northern Minnesota world reminiscent of the Coen brothers’ Fargo, The Doctor and Mr. Dylan details scenes of family crises, operating room mishaps, and courtroom confrontation, and concludes in a final twist that will leave readers questioning what is of value in the world we live in.

REVIEWS:

5.0 out of 5 stars The Doctor and Mr Dylan, March 3, 2015
By
prabha venugopal (chicago, il USA) – See all my reviews
Verified Purchase(What’s this?)
Gripping from the beginning to the end. Very well written, bringing to the forefront all the human emotions seen in an operating room spill over into real life. I cannot wait for Dr. Novak to wrote another book! As another physician in the same profession, my admiration for his book knows no limits.

Bang-Up Debut Novel, November 16, 2014

By Norm Goldman “Publisher & Editor of Bookpleasures”

This part legal and medical thriller is structured with a mixed bag of situations involving relationships, jealousy, evil, lies, courtroom drama, operating room mishaps as well as moments that engender conflicting and unexpected outcomes. Noteworthy is that as the suspense builds readers will become eager to uncover the truth involving a mishap concerning Nico and a surgical procedure that has unanticipated ramifications.

This is a bang-up debut from a writer who understands timing and is able to deliver hairpin turns, particularly involving the courtroom drama,that you would expect from a book of this genre.

TwinCities.com PIONEER PRESS Entertainment

by Mary Ann Grossman, Entertainment Editor, St. Paul Pioneer Press mgrossman@pioneerpress.com, January 4, 2015

“The Doctor & Mr. Dylan” by Rick Novak (Pegasus Books, $17.50)

Dr. Nico Antone doesn’t hide the fact he hates his wife, but he says he didn’t kill her during an operation. The authorities think otherwise and his trial is the riveting suspense in this novel that is part medical thriller, part legal thriller, part exploration of family relationships.

Nico is an anesthesiologist (as is the author) who leaves his wife, their plush life in California and his job at Stanford to move to his hometown of Hibbing so their son, Johnny, has a better chance of getting into a prestigious college. Johnny hates the idea of moving to a small, cold town, but he’s popular from the first day in school. Nico doesn’t do so well. He’s envied by Bobby, an anesthetist who’s jealous of the better-educated Nico. But it’s hard to take Bobby seriously, since he thinks he’s the young Bob Dylan and lives in the house where Bobby Zimmerman grew up. To complicate matters, Nico is attracted to the mother of the young woman his son is dating. When the two teens get in trouble, Nico’s furious, rich wife comes to Minnesota and needs an emergency operation that puts her on Nico’s operating table.

Novak grew up in Hibbing, where he worked in the iron ore mines and played on the U.S. Junior Men’s Curling championship teams of 1974 and ’75. After graduating from Carleton College, he earned a medical degree at the University of Chicago and spent 30-plus years at Stanford Hospital, where he was an associate professor of anesthesia and Deputy Chief of the Anesthesia Department. His courtroom scenes are based on his experiences as an expert witness.

The Physician’s Late-Night Reading List

Two Pritzker alums pen captivating tales

By Brooke E. O’Neill, University of Chicago Pritzker School of Medicine, editir, Medicine on the Midway Magazine

For most physicians, writing — patient notes, case histories, perhaps journal articles — is part of the job. But for anesthesiologist-novelist Rick Novak, MD’80, and neurosurgeon-memoirist Moris Senegor, MD’82, it’s a second career that consumes early morning hours long before they step into the OR.

Fans of John Grisham will find a kindred spirit in Novak, whose fast-paced medical thriller, The Doctor & Mr. Dylan (Pegasus Books, 2014), transports readers to rural Northern Minnesota, where an accomplished physician and a deranged anesthetist who thinks he’s rock legend Bob Dylan see their worlds collide in the most unexpected ways.

Delivering real-life twists and turns — and a love letter to the Bay Area — is Senegor’s Dogmeat: A Memoir of Love and Neurosurgery in San Francisco (Xlibris, 2014), a coming-of-age tale chronicling the author’s away rotation with renowned neurosurgeon Charles Wilson, MD, at the University of California, San Francisco. Brutally honest, it spares no details of a time Senegor, who also served as a resident under the University of Chicago’s famed neurosurgery chair Sean Mullan, MD, describes as “one of the biggest failures of my life.”

One a vividly imagined nail-biter, the other an intimate peek into the surgical suite, both books deliver an ample dose of intensity and drama.

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The Doctor and Mr. Dylan (Pegasus Books, 2014) by Rick Novak, MD’80

“I thought it was a novel way of killing someone,” said Rick Novak, deputy chief of anesthesiology at Stanford University, describing the imagined hospital death that was the genesis of his dark thriller The Doctor & Mr. Dylan. A huge Bob Dylan fan — the rock icon was born in Novak’s hometown of Hibbing, Minnesota, where the story takes place — he then dreamed up a possible culprit: a psychotic anesthetist who thinks he’s Dylan.

From there, the words flowed. “I would write whenever I was with my laptop and had a free moment: in mornings, in evenings, in gaps between cases,” said Novak, who also blogs about anesthesia topics. “I don’t sleep much.”

After finishing the manuscript — one year to write, another to edit — came the challenge of finding a publisher. “In anesthesia, I’m an expert,” Novak said. “In the literary world, I’m an unknown.” After 207 responses of “no, thanks” or no answer at all, he landed an agent. Two months later, she informed him that Pegasus Books had bought his debut novel.

“I started crying,” Novak admits. “I have a third grader and at the time the big word the class was learning was ‘perseverance.’ That was it exactly.”

Dr. Joseph Andresen, Editor, Santa Clara County Medical Association Medical Bulletin, from the January/February 2015 issue:

BOOK REVIEW “THE DOCTOR AND MR. DYLAN”

This past month, Dr. Rick Novak handed me a hardbound copy of his debut novel The Doctor and Mr. Dylan. Rick and I go way back. It was my first week of residency at Stanford when we first met. A newcomer to the operating room, all the smells and sounds were foreign to me despite my previous three years in the hospital as an internal medicine resident. Rick, a soft spoken Minnesotan at heart, in his second year of residency, took me under his wing and guided me through those first few bewildering months, sharing his experience and wisdom freely.

Fast-forward 30 years later. Dr. Rick Novak, a novel and mystery author? This was new to me as I sat down and opened the first page of The Doctor and Mr. Dylan. I have to admit that I didn’t know what to expect. Few books highlight a physician/anesthesiologist as a protagonist, and few books feature a SCCMA member as a physician/author. However, a medical-mystery theme novel wasn’t at the top of my must read list. With my 50-hour workweek, living and breathing medicine, imagining more emotional stress and drama was the furthest thing from my mind. However, three days later, as I turned the last page, and read the last few words. “life is a series of choices. I stuck my forefinger into the crook of the steering wheel, spun it hard to the left and …” This completed my 72-hour journey of and free moments I had, completely immersed in this story of life’s disappointments, human imperfections, and simple joys.

Rick, I can’t wait for your next book. Bravo!

Hibbingite writes twisted medical tale

HIBBING — Readers who are looking for a whodunit that will keep them up all night are in for a treat.

Hibbing native Rick Novak recently released his first book “The Doctor and Mr. Dylan,” a fiction set in Hibbing that merges anesthesia complications, a tumultuous marriage and the legend of Bob Dylan.

“The dialogue is sometimes funny, and there are lots of plot twists,” he said.

Novak said the book will not only entertain readers, but teach them about anesthesiology, Dylanology, the stressful race for elite college admission, and life on the Iron Range.

“The book is very conversational and streamlined,” he said. “I try to write as one would tell a story out loud.”

Novak said “The Doctor and Mr. Dylan” took him three years to perfect. He is currently working on his second book.

5.0 out of 5 stars I Sense We Have Another F.Scott Fitzgerald Emerging on the Literary Scene, December 1, 2014
By
Deann Brady (Sunnyvale, CA USA) – See all my reviews
(REAL NAME)
I found Rick Novak’s first novel, “The Doctor and Mr. Dylan,” a most exciting combination of biting sarcasm, mystery and daily activity spun with fresh new phrases that made me turn my ear back to listen to the literary cadence of his words again and again even though, on the other hand, I was anxious to turn the pages to see what would happen next. His brilliant handling of scenes is reminiscent of The Great Gatsby by F. Scott Fitzgerald. A compelling read!Deany Brady, author of “An Appalachian Childhood”

By

allan mishra

This review is from: The Doctor and Mr. Dylan (Kindle Edition)

Just finished Dr. Novak’s delightful novel. I sincerely enjoyed his honest take about the pressures and values that exist within California’s Silicon Valley. He also brought the North Country of Minnesota to life with memorable characters and a twisting, addictive plot. Buried beneath the fun and funny story is a deeper message about how to best care for your kids, your relationships and yourself. Very well written and highly recommended.

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

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