7 Reasons You’re Tired after Surgery

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Postsurgical fatigue introduction

Patients often question why they are so tired after surgery. Many patients think that because they have been “put to sleep with anesthesia” that they should be refreshed and have more energy as they recover from their surgery. However, the tired feeling (fatigue) after surgery is the usual situation for most patients and there are some reasons for this outcome.

Sleep deficit

Some reasons begin even before surgery. For example, many patients have anxiety about undergoing any type of surgery and find it difficult to sleep, especially right before the date of surgery. Consequently, many patients have a sleep deficit even before they undergo surgery. This sleep deficit must be made up so the body triggers "sleepiness or fatigue" as a way to pay off this deficit. Anesthetics do not make up for this sleep deficit, so the body still has it after surgery.

Anemia and blood loss

One of the consequences of low red blood count (anemia) is that person can have fatigue. If the patient has a history of anemia before surgery they are already primed to feel tired and sleepy after surgery. Even patients who are not anemic before surgery may become anemic during or after surgery because of blood loss during and after the procedure. In addition to feeling fatigued and/or sleepy, the patient who has lost blood may have a tendency to feel weak and/or dizzy when they try to sit up or stand up. Also, they may feel fatigued because they work harder to breathe since the anemia has decreased oxygen carrying capacity due to fewer red blood cells available to carry oxygen to the body's tissues.

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Fasting and loss of electrolytes and minerals

Before surgery, patients are often advised to fast to avoid problems (for example, vomiting, airway compromise, aspiration of gastrointestinal contents) during anesthesia and surgery. Fasting is often extended into the short post-operative period. This can result in a reduction or loss of electrolytes and minerals that are usually found in foods. Although fluids may be given during the surgery, they mainly supply fluid volume and do not contain all of the minerals and electrolytes that may be lost. For example, loss of sodium can cause drowsiness and muscle weakness. Loss of potassium (hypokalemia) can cause irregular heartbeats that can cause fatigue and weakness.

Medications

During or after surgery, a number of medications may be administered that are used to alter blood pressure during the procedure. Frequently used drugs are blood pressure medications like metoprolol (Lopressor) or diuretics (for example, hydrochlorothiazide) to reduce blood pressure. Side effects of these drugs include fatigue. After surgery, medications like benzodiazepines (for example, lorazepam) may be used for sedation and/or muscle spasms. The benzodiazepines are also used to treat insomnia and can cause sleepiness. In many individuals, antibiotics are started during or right after the surgical procedure. Some antibiotics like cephalexin (Keflex) and trimethoprim and sulfamethoxazole (Bactrim) can cause fatigue.

Exercise and physical stress

Exercise and other activities such as strenuous work normally cause fatigue because such activity stresses the body. In order to recover, the body triggers a fatigue response so that the person will be encouraged to rest. This is a normal stress-recovery cycle. Undergoing surgery where the body is given medications and traumatized by procedures can cause fatigue as the body enters into the repairing and healing mode.

Aging and overall health

With normal aging or from an overall decline in health due to progressive medical problems, there is less ability for the body to rapidly heal and to cope with moderately strenuous exercises and/or activities. The result is that individuals become fatigued quicker and the fatigue usually lasts somewhat longer. Exposure to the stress of surgery (potentially new drug and/or medications, blood loss and/or anemia, electrolyte and mineral imbalances plus the new demands for the body to heal the surgical trauma) then adds to their fatigue after surgery.

Depression

Depression, both before and after surgery, can produce fatigue. Some patients have fatigue caused by anxiety about pain control, surgical outcome, and concerns about new medications or the need for rehabilitation, cost of care, family situations, and many other problems. Discovering and addressing depression and anxiety before and after surgery may help reduce mental fatigue seen in some surgical patients.

Nevertheless, it is possible to reduce some of the fatigue many patients feel after surgical procedures. Keeping blood loss (anemia) to a minimum; replacing fluid, electrolytes and minerals quickly; avoiding potentially fatigue-inducing medications; and reducing stress (both mental and physical) before and after surgery will likely reduce fatigue. Finally, it's likely that after any surgery a person will feel some fatigue. For goodness sake, don't keep a postsurgical patient awake right after surgery with an excessive number of visitors who want to talk! Let the surgical patient rest to reduce fatigue and speed recovery.

REFERENCES:

"Side Effects of Surgery." Cancer.net.

Lederer, E., et al. “Hypokalemia.” Medscape. 7 Oct. 2015.

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Reviewed on 11/23/2015
References
REFERENCES:

"Side Effects of Surgery." Cancer.net.

Lederer, E., et al. “Hypokalemia.” Medscape. 7 Oct. 2015.

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