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.

Patients sometimes say, “Why did it take me so long to wake up after anesthesia?” when they discussed their previous anesthetic history. They are fearful that something is wrong with them, and they will always have delayed awakenings.


Certain patients have consistent bad experiences from a past general anesthetic. A previous anesthetic left them somnolent all day after surgery, and/or they felt sleepy or ill for days after a previous surgery. They wonder if they are at increased risk for anesthesia, if something went wrong in their past anesthetics, and whether they can do about it.

Whenever a patient tells me they’ve been very sensitive to anesthesia in the past, they’re always right. The good news for patients is: you probably can do something to help yourself in the future.

The most valuable thing you can do is obtain a copy of your previous anesthetic record and Post Anesthesia Recovery Room records from a surgery in which you had a perceived prolonged wake up. Save these documents and present them to future anesthesiologists. Inform future anesthesiologists regarding your history of prolonged sedation, and they can make adjustments in their drug delivery and techniques to attempt to avoid the same problems. Future anesthesiologists can administer lower doses of medications or fewer medications as they deem advisable.

The world’s foremost anesthesia textbook, Miller’s Anesthesia, does not have a specific section or chapter on the topic of avoiding prolonged wake ups. If you search the Internet or the PubMed website for a discussion of the topic “prolonged awakening from anesthesia,” you’ll find a shortage of useful information. Few papers have been published on the topic.

But every case of prolonged wake-up has its own story. General anesthetics and sedative drugs work by anesthetizing the brain and central nervous system. Based on thirty years as an anesthesiologist, the personal administration of 25,000+ anesthetics, and information from medical textbooks, what follows are lists of the primary factors which cause prolonged sedation after anesthesia.

Patient characteristics that correlate with prolonged awakening after anesthesia:

  1. Patients with a past history of slow awakening from anesthesia.
  2. Patients who are naïve to central nervous system depressants in their weekly life. That is, they never or very rarely drink alcohol, and never take sedating medications of any kind. Chronic alcohol consumption increases the dose of propofol required to induce loss of consciousness (Fassoulaki, A et al. Chronic alcoholism increases the induction dose of propofol in humans.Anesthesia and Analgesia. 1993;77(3):553-556). Conversely, patients who have zero or modest exposure to drugs like alcohol can require lower doses of anesthetic drugs.
  3. Patients who claim they are “sensitive to all medicines.”
  4. Elderly patients. As you age your ability to metabolize medications decreases. Older persons, especially those over the age of 70-80 years, require lower doses.
  5. Obese patients. Intravenous doses of medications are calculated according to a patient’s weight, but this number should be their lean body weight, not their weight including excess fat. Imagine two patients who are the same age and height, but one weighs 150 pounds and the second weighs 300 pounds. The second patient will need higher doses than the first, but will not require twice the dose. Markedly increasing the weight of fat cells does not mean the brain needs twice the dose of medications.
  6. Petite patients. What if an anesthesia provider administers his or her standard recipe for anesthesia without noticing that their current patient only weighs 88 pounds? Standard doses for a 150-pound person will be excessive in an 88-pound patient.
  7. Patients with decreased function of one or more of the major organ systems, that is the heart, lungs, liver, or kidney. Depending on the medication, one or more of these organ systems are required to clear the drug from the body. A patient with heart failure or decreased cardiac output will not be able to pump the drug efficiently throughout the body to the lungs, liver, or kidneys to clear the drug. A patient with decreased lung function/ventilation will not be able to exhale vapor anesthetics promptly. A patient with decreased liver function will not be able to clear certain drugs like narcotics from the body promptly. A patient with decreased kidney function will not be able to clear paralyzing drugs such as the muscle relaxant rocuronium from the body promptly.
  8. Patients with an abnormal brain. For example, patients with dementia, delirium, congenital developmental delay, or any organic brain syndrome may experience increased post-operative sedation due to exaggerated effects of the anesthetic medications on their brains.

Medical circumstances that contribute to prolonged patient awakening after anesthesia:

  1. The longer the surgery and anesthetic duration, the longer the wake up time. This is because the longer exposure to anesthetic drugs requires a longer time to exhale the vapor drugs or to clear and metabolize the intravenous drugs.
  2. The more complex the surgery, the longer the wake up time. Certain surgeries, for example a liver transplant, are so complex that an anesthesiologist often plans to keep the patient asleep in the intensive care unit after the surgery until the first post-operative day.
  3. An inexperienced anesthetist may resort to a standard recipe for every patient, and administer a more heavy-handed concoction of anesthetic drugs than are necessary for patients in our first list above.
  4. Painful surgery. Any surgery which hurts a great deal will require increased pain-relieving medications in the Post Anesthesia Recovery Room. Pain-relieving medications include narcotics such as morphine or fentanyl, which are sedating and sometimes nauseating. The less of these medicines you require, the more alert you’ll feel. Local anesthetic injections by the surgeon or a regional anesthesia nerve block by the anesthesiologist can decrease your need for narcotics, decrease post-operative pain, and decrease your risk of prolonged sedation after surgery.

You have little control over the drugs you’ll be given during surgery, but please inform and remind your anesthesiologist regarding any characteristics from the first list above. An honest discussion of your previous bad anesthetic experience(s), together with obtaining a copy of a previous anesthetic record(s), may grant you some control regarding how sedated you feel after future anesthetic experiences.

YOU are your own best advocate. Don’t be afraid to inform your anesthesiologist.


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?

Will I Be Nauseated After General Anesthesia?

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

Should You Cancel Anesthesia for a Potassium Level of 3.6?

12 Important Things to Know as You Near the End of Your Anesthesia Training

Should You Cancel Surgery For a Blood Pressure = 178/108?

Advice For Passing the Anesthesia Oral Board Exams

What Personal Characteristics are Necessary to Become a Successful Anesthesiologist?