Is Anesthesia Safe?
The answer to the question of whether general anesthesia is safe for people with high blood pressure is: usually.
For elective surgery, blood pressure control should be optimized through lifestyle changes and medication, if necessary. For emergency surgery, anesthesiologists will use their medications to control the blood pressure during anesthesia.
Like most issues in anesthesia, and medicine in general, there are many variables that determine the risk in different situations.
Among the determining factors are:
- Level of blood pressure elevation
- Type of surgery to be done
- Patient's medication regimen
- Coexisting diseases
Classifications of Blood Pressure
|Classification||Systolic Blood Pressure||Diastolic Blood Pressure|
Normal Blood Pressure (Healthy)
Prehypertension - Stage 1
Prehypertension - Stage 2
Severe Hypertension (Stage 2 Hypertension)
Hypertension and Pre-Hypertension Defined
As the blood flows through your arteries, it exerts pressure on the walls of those arteries. Various medical devices can measure that pressure. The systolic (top) number is the highest pressure detectable during a cardiac pumping cycle. The diastolic (bottom) number is the number representing the pressure of the blood against the arteries when the heart rests between heartbeats.
Not long ago, hypertension was defined as anything higher than 140/90. As more data is collected about healthy blood pressure, new definitions have emerged.
Any systolic blood pressure between 120 and 139 is called prehypertension. Diastolic readings in the range of 80-89 also are "prehypertensive."
More clinically significant might be the term "stage 2 prehypertension." This definition is reserved for blood pressures in the 130-139 systolic range and diastolic pressure between 85 and 89. Studies, as cited and summarized in an excellent review in the November 2010 issue of Cardiology Clinics* show that the risk of cardiac events (heart attack, stroke, etc.) goes up 50 to 130 percent for people with blood pressure in this range!
*Brent M. Egan, MDa,, Daniel T. Lackland, DrPHa, Daniel W. Jones, MDb; “Prehypertension: An Opportunity for a New Public Health Paradigm”; Cardiology Clinic 28 (2010): 561–569.
Blood Pressure and Anesthesia
Although it may not be ideal, general anesthesia is usually going to be safe for people with high blood pressure (unless it is very high). During anesthesia, we are usually able to control the blood pressure with our medications. The risk after surgery, however, still exists.
Surgery and anesthesia cause stress on the body. During surgery, it is not unusual to have swings in blood pressure from very low to a bit too high. Anesthesia blunts these changes to some degree, but there are still ups and downs in blood pressure. We can treat these changes with medications.
Blood pressure is likely to be lowest right after the induction of anesthesia (when you go to sleep) It may stay low during the anesthetic, as well. This is related to the fact that anesthetics cause blood vessels to dilate; i.e., relax. It will be highest during anesthesia emergence (waking up).
In general, the less well-controlled your blood pressure, the more likely it is to cause problems during and after surgery and anesthesia. Even though anesthesiologists can control blood pressure to some degree under anesthesia, there can still be uncontrollable or unpredictable reactions when preop blood pressure is too high.
Read More From Healthproadvice
High Blood Pressure and Surgery Risks
In general, these risks are increased as blood pressure increases:
- Bleeding: As logic would tell you, if there is more pressure against the blood vessels, bleeding during—and potentially after—the surgery will be brisker.
- Unstable Blood Pressure and Heart Rate: If your hypertension isn’t controlled and stable preoperatively, the risk of dangerous drops and spikes while under anesthesia increases.
- Heart Attack: Cardiovascular risk goes up with increases in blood pressure. If you have pre-hypertension, you are 3.5 times more likely to have a heart attack than if you had lower blood pressure. This risk would also be true for postoperative heart attacks.
- Stroke: High blood pressure is always a risk factor for stroke, especially in those already at risk. If hypertension is not well controlled before surgery, this risk can be significant.
Most of the time, risk will increase proportionally with blood pressure. Most anesthesiologists will cancel your surgery if your blood pressure is in the range of 200/100. Often, and especially for some types of surgery (vascular surgery, for example), even lower values will result in cancellation or delay of surgery.
Your category is determined by the higher value. For example, if your blood pressure is 114/86, you are still classified as prehypertensive, type 2
This content is for informational purposes only and does not substitute for formal and individualized diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed medical professional. Do not stop or alter your current course of treatment. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
dodan on February 18, 2016:
I had a total knee replacement surgery one year ago. I have high blood pressure, but is controlled by medication. I told the surgeon before hand that I have high blood pressure and he told me not to worry about it I was in good hands. As the surgery started my pressure went very high I was told that it up to 255/120, I was in ICU for 3 days ( heavily sedated) to bring my pressure down. Now, I am afraid to have any surgery done for this reason. The doctors said I have Renal Artery Stenosis, what should I do in this circumstance if I should need surgery again? Lucky to be here.
Martin Drew on April 14, 2015:
The issue of hypertension, anaesthesia and psychology
Melvin Porter from New Jersey, USA on May 09, 2012:
TahoeDoc, thanks for the response. I can see it gets more complicated under these circumstances and your work becomes more demanding.
TahoeDoc (author) from Lake Tahoe, California on May 08, 2012:
Hi Mel- good to see you!
Emergency surgery is a whole different ball game. In those cases, you have no choice and must do the best you can with what you have. The benefits outweigh the risks or more correctly, the lesser risks outweigh the certain risk of death if the patient is left untreated..
This question, though, reminds me of cases (not that uncommon) that go something like this. Here is an example of emergency surgery with high blood pressure...
*Elderly patient comes to ER with stroke symptoms or other neurologic changes.
*Patient is taking blood thinners because of irregular heart rhythm
*Patient found to have blood pressure of 220/115- maybe forgot to take meds for a couple days
*Patient is found to be bleeding into or around their brain
*Emergency surgery -everyone going full-throttle (almost always at the 'end' of a 20 hour day for some reason)
So the high blood pressure likely caused a blood vessel in the head to rupture. The blood thinners make it keep bleeding and bleeding...
1) keep patient alive until the surgeon can get to and fix the problem
2) control the blood pressure - don't want it too high (bleeding) or too low (dead brain tissue) without causing dangerous changes in heart rate or other vital signs. Constant adjustment of anesthesia and (sometimes frantic) manipulation with other meds usually works ok.
3) do a bunch of other things-- put in IVs, arterial lines, central lines, manage the respirator to keep the CO2 in the range to help the intracranial pressure, transfuse blood, keep the patient asleep, pretty much all at the same time...
As you can imagine, the outcome isn't always great, but sometimes, you can actually save them. Of course, the surgeon will get all the credit (and they are amazing-I love surgeons) because no one has any idea what anesthesiologists do. :)
Melvin Porter from New Jersey, USA on May 08, 2012:
Very interesting hub. I never knew a doctor can cancel surgery if the patient's blood pressure is too high. What happens if the patient is in an emergency or life threatening situation?
meloncauli from UK on April 29, 2012:
A very thought provoking hub.I was left with a high blood pressure after an operation which was a bit scary as I have never had blood pressure problems before. It did go down after a few hours. Very interesting.
Pamela Oglesby from Sunny Florida on April 29, 2012:
I developed hypertension about 3 years ago but it 9is well controlled by medication. This is an excellent hub for anyone with hypertension. Up and useful.
Marcy Goodfleisch from Planet Earth on April 28, 2012:
What an outstanding article! My mother had high blood pressure, but (thankfully), it doesn't seem to have hit my generation. However, I really haven't understood much about it. I appreciate the information you've given us - especially since most of us will either deal with it personally or through a family member who has it.
alliemacb from Scotland on April 28, 2012:
This is a really useful hub that outlines the risks of high blood pressure and anaesthesia really well. Voted up and useful.
usmlefacts from US on April 28, 2012:
Useful information for many people.