AnesthesiaMACSNCT07022951
The Million Anesthesia Cases Study (MACS) - a Cohort Study of Preoperative Fasting and Perioperative Outcomes
An observational study of Anesthesia and Sedation, run by Massachusetts General Hospital at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Anesthesia, Sedation, Monitored Anesthesia Care
- What is being tested?
- Preoperative fasting
- How many people
- 1,200,000 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jan 2016to 31 Dec 2030
- Phase
- Observational
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: We will include all anesthesia cases at participating institutions.
Who may be able to join
- Diagnostic or therapeutic procedure with anesthesia care (general anesthesia, regional anesthesia, sedation, or a combination of the above)
Who cannot join
- Not receiving anesthesia care
- Lack of medical record data in Epic electronic medical record system
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Mass General Brigham Hospital Network of secondary, tertiary, and quaternary care hospitals
Boston, Massachusetts, 02114
Alexander Nagrebetsky, MD, MSc, 617-724-3292, anagrebetsky@mgh.harvard.edu
About this study
Official title: The Million Anesthesia Cases Study (MACS) - Retrospective and Prospective Characterization of Perioperative Fasting Practices and Their Effects on Clinical Outcomes
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.
- Conditions
- Anesthesia, Sedation, Monitored Anesthesia Care, Procedure, Surgery, Day, Surgery
- Being tested
- Preoperative fasting
- Keywords
- preoperative fasting, perioperative pulmonary aspiration, perioperative complications, postoperative nausea and vomiting, perioperative hypoglycemia, perioperative hyperglycemia, perioperative hypotension, myocardial injury after noncardiac surgery, perioperative acute kidney injury, clear liquid fasting
- Medical subject headings
- Postoperative Nausea and Vomiting
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Preoperative fastingOther
This cohort study assesses the duration of preoperative fasting and its clinical effects
| Study group | Role | What they receive |
|---|---|---|
| Patients who receive anesthesia care | Not described Receives: Other: Preoperative fasting |
What is being measured
The primary outcome is the main question the study is designed to answer.
Postoperative nausea and vomiting (PONV)
The co-primary outcome of PONV is defined as administration ≥ 1 antiemetic drug within 12 h postoperatively.
Measured: 12 hours postoperatively
Intraoperative hypotension
The co-primary outcome of intraoperative hypotension is defined as an area under the curve of intraoperative mean arterial pressure <65 mm Hg.
Measured: Intraoperative period.
Perioperative acute kidney injury (AKI)
The co-primary outcome of perioperative AKI is defined as stage 1 or higher, based on Kidney Disease Improving Global Outcomes criteria (creatinine rise ≥ 0.3 mg/dl within 48 h or ≥ 1.5 times baseline) from postoperative day (POD) 0 until POD 7
Measured: Postoperative days 0 to 7
Secondary outcomes (6)
Incidence of prolonged preoperative fasting for clear liquids
Incidence of prolonged preoperative fasting for clear liquids is defined as fasting that exceeds the American Society of Anesthesiologists-recommended duration by a factor of 2 or more (≥ 4 hours).
Measured: 48 hours preoperatively
Severity of prolonged clear liquid fasting
Severity of prolonged clear liquid fasting is defined as the frequency of fasting duration that exceeds the currently recommended by 2x, 4x, 6x, etc.
Measured: 48 hours preoperatively
Perioperative hypoglycemia
Perioperative hypoglycemia: any blood glucose concentration < 70 mg/dL from 12 h before to 24 h after the procedure
Measured: 12 hours preoperatively to 24 hours postoperatively
Perioperative hyperglycemia
Perioperative hyperglycemia is defined as any blood glucose concentration > 140 mg/dL from 12 h before to 24 h after the procedure.
Measured: 12 hours preoperatively to 24 hours postoperatively
Perioperative AKI stage 2 or higher.
Perioperative AKI stage 2 or higher is defined as creatinine at least twice the baseline level between POD0 to POD7.
Measured: Postoperative days 0 to 7
Myocardial injury after noncardiac surgery (MINS)
Myocardial injury after noncardiac surgery is defined as increased cardiac troponin I above the 99th percentile within 3 days after surgery.
Measured: Postoperative day 0 to 3
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Jun 2025
- Study start1 Jan 2016
- Primary completion31 Dec 2028 (estimated)
- Study completion31 Dec 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AnesthesiaStudies of the same condition, open and under way.
- More trials run by Massachusetts General HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Other
- Enrolment
- 1,200,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Massachusetts General Hospital
- Sponsor type
- University, hospital or other
- Collaborators
- Anesthesia Patient Safety Foundation
- Responsible party
- Principal investigator, Alexander Nagrebetsky, MD MSc, Massachusetts General Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07022951
- Sponsor's protocol ID
- 2023P001743
- Acronym
- MACS
- Status last verified
- Mar 2026
- First submitted
- 6 Jun 2025
- Last updated
- 8 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No