Monitored Anesthesia Care (MAC)

What Is Monitored Anesthesia Care?

When most people think about anesthesia, they picture being completely put to sleep for a major operation. But a large number of medical procedures are performed each year using a different approach called Monitored Anesthesia Care, or MAC. Under MAC, a patient receives sedative and pain-relieving medications to keep them comfortable and relaxed during a procedure without being fully unconscious the way they would be under general anesthesia. Depending on the doses involved, a patient under MAC may be in a light, drowsy state where they can still respond to questions, or they may be deeply sedated and entirely unresponsive. The depth of sedation can — and frequently does — shift during a procedure.

An anesthesiologist (a physician who specializes in anesthesia) or a CRNA — a Certified Registered Nurse Anesthetist, a specially trained advanced practice nurse licensed to administer anesthesia — is responsible for giving the medications and watching over the patient throughout the procedure. Their job is to keep the patient comfortable while continuously monitoring for any signs that the patient is experiencing a problem.

MAC is used across a wide range of common medical procedures. A large portion of outpatient and same-day surgical procedures are conducted using MAC rather than general anesthesia, including:

• Colonoscopies and upper endoscopies (procedures in which a camera is inserted into the digestive tract to examine the colon or stomach)
• Cataract surgery, in which a clouded lens of the eye is replaced
• Minor orthopedic procedures
• Cardiac catheterizations (procedures used to examine the heart and its blood vessels), and,
• Interventional pain management procedures — such as nerve blocks or spinal injections

How Common Are MAC Complications, and Who Is Most at Risk?

Although MAC is often described as a lighter, safer alternative to general anesthesia, it carries real and potentially life-threatening risks. Studies and adverse event reporting have consistently shown that a meaningful number of serious patient injuries and deaths each year are related to complications arising during MAC. Because MAC involves sedating a patient who continues to breathe on their own — without the protection of a breathing tube that is standard in general anesthesia — the margin for error can be narrow.

Certain patients face a substantially higher risk of complications during MAC. Elderly patients are particularly vulnerable, as aging affects how the body processes sedative medications and how quickly complications can develop. Patients with obesity carry greater risk because excess body weight can make breathing during sedation more difficult and can make it harder to support or rescue the airway in an emergency. Patients with obstructive sleep apnea — commonly called OSA, a condition in which the airway repeatedly narrows or closes during sleep, causing disrupted breathing — are at elevated risk because sedation can trigger the same airway problems that occur during sleep, often without any warning. Patients with underlying heart or lung disease, and patients with multiple comorbidities (meaning several medical conditions occurring at the same time), face compounded risks because their bodies have less reserve to tolerate a complication before it becomes catastrophic.

Injuries stemming from MAC complications are among the most severe possible. Respiratory depression — a dangerous slowing or suppression of breathing — can rapidly lead to hypoxia (dangerously low oxygen levels in the blood), anoxic brain injury (brain damage caused by oxygen deprivation), cardiac arrest, and death. Burn injuries related to the use of electrical surgical instruments are another recognized category of serious harm in the MAC setting.

These complications can occur in any setting where MAC is administered, including hospital operating rooms, outpatient surgical centers, endoscopy suites, and office-based procedure settings. Office-based and freestanding outpatient settings may carry a particularly elevated risk in some cases, because they may have fewer monitoring resources, less immediately available emergency equipment, and smaller teams to respond to a crisis.

Avoidable Medical Errors in MAC: What Goes Wrong and Why

Many of the most serious injuries associated with MAC are not the result of unforeseeable accidents. They are the product of specific, identifiable failures by the medical professionals responsible for the patient’s care. Understanding what those failures look like — and why they constitute avoidable medical errors — is essential for any patient or family trying to make sense of what happened to them or their loved one.

Failure to Perform Proper Pre-Procedure Evaluation and Risk Assessment

Before any sedation is administered, the anesthesia provider has a professional duty to conduct a thorough pre-anesthesia evaluation of the patient. This evaluation should encompass a complete review of the patient’s medical history, current medications, known allergies, any previous experiences with anesthesia, the anatomy of the patient’s airway, and any risk factors that could affect how the patient tolerates sedation. The provider should use this information to determine whether MAC is appropriate for this patient, what type and depth of sedation is suitable, and what precautions should be in place. When an anesthesia provider skips this evaluation, performs it hastily, or fails to communicate identified risks to the rest of the surgical team, the consequences can be severe. The wrong type of anesthesia may be selected, critical precautions may not be taken, and a patient who should have been treated with extra caution may instead receive standard-dose sedation with no precautions for their underlying vulnerabilities.

Over-Sedation and Respiratory Depression

One of the most serious and most avoidable errors in MAC is giving a patient too much sedative or pain-relieving medication — a problem known as over-sedation. When a patient receives excessive doses of these medications, the medications can suppress the brain’s signal to breathe, a condition called respiratory depression. As the patient’s breathing slows or stops, oxygen levels in the blood fall, leading to hypoxia. If hypoxia is not identified and corrected within a matter of minutes, permanent brain damage — or death — can result.

The risk of over-sedation is significantly greater in patients with OSA, obesity, or significant lung disease, because their respiratory systems are already under stress. The anesthesia provider’s obligation is to carefully adjust the doses of sedative and analgesic medications based on the patient’s individual risk profile, their response to the medications being given, and continuous assessment of how they are tolerating the sedation. Failing to do so is a recognized form of anesthesia negligence.

Failure to Monitor the Patient

Continuous monitoring of the patient throughout a MAC procedure is a fundamental requirement of the standard of care. An anesthesia provider is required to monitor the patient’s oxygen saturation (measured by a device called a pulse oximeter, which is clipped to the finger and reads oxygen levels in the blood), breathing rate and pattern, heart rate, blood pressure, and level of consciousness throughout the procedure. Monitoring serves as the early warning system for complications: it is how the anesthesia provider learns that a patient is beginning to develop respiratory depression before it progresses to a crisis.

Failures in monitoring can take many forms — inattention to monitors while focusing on other tasks, insufficient staffing so that no qualified person is watching the patient’s vital signs, equipment malfunctions that go unaddressed, or failure to respond when a monitor alarm sounds. Any of these failures can allow a patient’s condition to deteriorate from a manageable early warning sign to a catastrophic emergency — and it can happen in a matter of minutes.

Failure to Recognize the Need for Intervention and Escalate Care

Recognizing that a patient under MAC is in distress — and responding promptly — is one of the most critical responsibilities an anesthesia provider has. When monitoring reveals that a patient’s oxygen levels are dropping, their breathing is becoming shallow or irregular, or they are becoming unresponsive, the anesthesia provider must act immediately. Depending on the situation, appropriate intervention may include repositioning the airway, providing supplemental oxygen through a mask, using an airway support device, administering medications to reverse the effects of sedation, or — when necessary — converting to general anesthesia by intubating the patient, meaning placing a flexible breathing tube into the airway to take over the work of breathing mechanically. Each of these interventions requires recognition of the problem and a timely, decisive response. When an anesthesia provider fails to recognize early warning signs, delays intervention, or hesitates when the situation calls for urgent escalation, what might have been a correctable complication can become an irreversible tragedy.

Burn Injuries from Electrocautery

A less widely known but serious risk in the MAC setting involves the use of electrocautery — a surgical instrument that uses electrical current either to cut tissue or to seal off bleeding blood vessels. During many procedures performed under MAC, patients receive supplemental oxygen delivered through a nasal cannula (a small tube that rests at the nostrils) or a face mask. Oxygen itself is highly flammable, and when it accumulates around the face, mouth, or upper airway — as it commonly does during MAC — and electrocautery is used in the same area, the risk of igniting a fire is real.

These fires can cause severe burns to the patient’s face, mouth, or airway. Preventing these injuries requires careful coordination between the anesthesia provider and the surgeon: the anesthesia provider must manage oxygen delivery in a way that minimizes the accumulation of oxygen near the surgical site, and the surgeon must be aware of these risks and communicate with the anesthesia provider before using electrocautery. Failure on either side of this equation can result in a preventable and devastating burn injury.

Other Failures in Patient Management

Beyond the categories addressed above, there are additional failures in patient management that can contribute to serious harm during MAC. Emergency resuscitation equipment — including a defibrillator, airway management supplies, and emergency medications — must be immediately available whenever MAC is being administered; if it is not present or not functioning, the response to a crisis will be fatally delayed.

A trained team member capable of assisting in an emergency must be available; it is not sufficient for a single provider to manage both the anesthesia and the surgical procedure simultaneously without backup. Ongoing documentation of the patient’s condition, medications received, and vital signs throughout the procedure is essential for patient safety and to enable effective communication if care needs to be transferred to another provider. And the patient must have functioning intravenous (IV) access — a line placed in a vein — throughout the procedure so that emergency medications can be administered without delay if a crisis occurs. Each of these requirements reflects a basic element of safe anesthesia care, and failure to meet any of them can transform an urgent, yet manageable situation into one with catastrophic results.

When MAC Errors Become Medical Malpractice

Not every complication that occurs during MAC is the result of a medical error. Some patients experience adverse events even when their care team does everything right. But when an anesthesia provider or another member of the surgical team fails to meet the applicable standard of care — the level of skill, attention, and judgment that a reasonably competent anesthesia professional in the same specialty would have exercised under the same circumstances — and that failure is what caused the patient’s injury, the patient or their family may have a viable claim for medical malpractice.

MAC malpractice cases are not simple. They require a thorough investigation of the patient’s medical records, the anesthesia documentation, the monitoring data, and the sequence of events leading to the injury. They require the analysis and testimony of qualified anesthesia experts who can explain, in terms a jury can understand, exactly what the standard of care required and precisely how the providers involved failed to meet it. They are not cases for lawyers who lack deep experience in complex medical negligence litigation.

At Lupetin & Unatin, we have spent decades representing patients and families who have been seriously harmed by anesthesia errors. We understand the medicine. We work with leading anesthesia experts from across the country. We know how to investigate these cases, how to build them, and how to take them to trial when that is what it takes to get our clients the justice they deserve.