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The Million Anesthesia Cases Study (MACS) - a Cohort Study of Preoperative Fasting and Perioperative Outcomes
The Million Anesthesia Cases Study (MACS) - Retrospective and Prospective Characterization of Perioperative Fasting Practices and Their Effects on Clinical Outcomes
Who can join
All ages · All sexes
Full eligibility criteria
Inclusion Criteria: * Diagnostic or therapeutic procedure with anesthesia care (general anesthesia, regional anesthesia, sedation, or a combination of the above) Exclusion Criteria: * Not receiving anesthesia care * Lack of medical record data in Epic electronic medical record system
About the study
Perioperative fasting has historically been viewed as a low-risk intervention. However, preliminary data indicate that perioperative loss of nutrition and fluids is likely harmful. This study intends to characterize perioperative fasting practices and their potential effects on clinical outcomes through possible effects on patient well-being (anxiety, hunger, thirst), physiology (hypovolemia, hypotension), perioperative aspiration, etc. The research team hypothesized that in addition to known adverse effects on patients' well-being, prolonged preoperative fasting adversely affects circulating blood volume-related (hypotension, decreased urine output etc.) and glucose metabolism-related (e.g., hypo/hyperglycemia) perioperative physiology. The investigators will also test for an association between the duration of preoperative fasting and the risk of perioperative pulmonary aspiration.
Additional knowledge on the potential adverse effects of preoperative fasting will inform preoperative fasting policies and research interventions that are relevant to hundreds of millions of patients subjected to preoperative/preprocedural fasting worldwide each year.
What is being tested
- Preoperative fasting (other)
Sponsor: Massachusetts General Hospital · Participants: 1,200,000 · Started: Jan 1, 2016
Contact the study team
- Alexander Nagrebetsky, MD, MSc · Phone: 617-724-3292
Official record on ClinicalTrials.gov — NCT07022951
Locations in the U.S.
| Massachusetts | Mass General Brigham Hospital Network of secondary, tertiary, and quaternary care hospitals, Boston |
Conditions
From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.