Full Moon Fails to Foil Surgery

Study: Moon Phases, Time of Day, Time of Year Do Not Affect Heart Surgery Outcomes

Medically Reviewed by Louise Chang, MD on September 22, 2009

Sept. 23, 2009 -- Full moon. Friday. After 5 p.m. Late summer. They say these are bad times to schedule surgery.

And except for the full moon hex, there are good reasons to think so. Surgical teams may be tired at the end of the day, worn out at the end of the week, or less experienced when new residents arrive in July and August.

But however reasonable or unreasonable, none of these theories holds water, find Cleveland Clinic researchers Daniel I. Sessler, MD; C. Allen Bashour, MD; and colleagues.

"This investigation can help assure future patients who may be concerned -- operation timing and moon phase did not affect outcome in our study," Bashour tells WebMD.

Sessler's and Bashour's team pored over records from 18,597 heart bypass surgeries performed at their hospital from January 1993 through June 2006.

During that period, 1.4% of the patients did not survive their hospital stay. Nearly one in 20 patients suffered some kind of bad outcome, including:

  • In-hospital death
  • Heart attack after the operation
  • Brain damage
  • Serious infection
  • Kidney failure
  • Mechanical ventilation for more than 72 hours

But none of these risks was more likely at any time of the day, day of the week, month of the year, or phase of the moon.

Why? Sessler and Bashour note that there's abundant research to show that people make more mistakes when they are tired or doing shift work. But they say that doctors and hospitals set up systems to avoid this kind of problem -- and that at least when it comes to elective heart bypass surgery, these systems work.

"Well established protocol-based practices that reduce variability" counter "daily circadian rhythm effects, workweek fatigue, and training variability," Sessler says in a news release.

The findings appear in the October issue of Anesthesiology, the journal of the American Society of Anesthesiologists.

Show Sources


Tan, P.J. Anesthesiology, October 2009; manuscript received ahead of print.

C. Allen Bashour, MD, associate medical director, cardiovascular ICU, Cleveland Clinic.

News release, Cleveland Clinic.

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