Article

Reduced Sedation for Retinal Surgery

Techniques and technology have nearly eliminated the need for general anesthesia.

Operating on patients who are awake and aware is a growing trend among surgeons. According to a recent article in the New York Times, orthopedics is the specialty performing the most awake-and-aware cases.1 But it’s also being tried in oncologic, thoracic, vascular, urology, otolaryngology, and cosmetic surgeries.

What the Times article didn’t mention was that retinal surgeons have been operating on awake-and-aware patients for more than a decade. In fact, it’s the method preferred by most retinal surgeons.

“Nowadays, at least for me, there has to be an excuse to put somebody to sleep,” says Michael Ober, MD, a partner at Retinal Consultants of Michigan and Adjunct Teaching Faculty at Henry Ford Hospital in Detroit. “It would be unusual for me to say that somebody should be done under general anesthesia.”

In the past 8 years, Dr. Ober says that 95% to 98% of surgeries have been on awake-and-aware patients. The number is even higher for Seenu M. Hariprasad, MD, chief of the vitreoretinal service and director of clinical research in the department of ophthalmology and visual science at the University of Chicago Medical Center. He estimates that 99.5% of his surgeries are on patients who are sedated but otherwise awake and aware. Neither doctor offers patients a general anesthesia option.

“I don’t give them the option because I don’t think it’s necessary,” Dr. Hariprasad says. With general anesthesia, “you are taking on so much risk with no apparent benefit.”

The benefit to operating on sedated but awake patients is chiefly patient safety. General anesthesia presents risks ranging from aspiration to a systemic reaction to anesthetic drugs. Many older adults take a laundry list of medications that can interact with anesthesia drugs.

“You don’t die from eye surgery,” says Jorge Calzada, MD, a retinal surgeon at the Charles Retinal Institute in Memphis, Tennessee. “You don’t bleed out from eye surgery. When any patient has a real systemic problem during eye surgery, it’s nearly always related to complications from anesthesia.”

Sedated patients also recover faster. A fast recovery without nausea, vomiting, or other postsurgical concerns is not only great for the patient but allows for a quick turnover of the operating room and better use of the practice’s resources.

Awake-and-aware surgery with a retrobulbar block is much safer than general anesthesia. But there still are risks of a retrobulbar block, such as hemorrhage and perforation of the eyeball, serious complications that have been documented in the literature.

“These are exceedingly rare and very unusual in capable hands,” Dr. Hariprasad says. “The key is that, in experienced hands, a retrobulbar block can be very safe. I will take a local complication around the eye anytime over a systemic complication from general anesthesia.”

EVOLUTION TO MINIMAL SEDATION

In the 1980s and early 1990s, because retinal surgeries were long and often required cutting open the eye, patients had to be anesthetized. As recently as 2005, when Dr. Ober was finishing his fellowship, retinal surgeons still debated anesthesia vs sedation.

“There was definitely more thought put into it at the time as far as who was appropriate to be awake and who was more appropriate to be asleep,” he remembers.

The decision often depended on the type of surgery being performed. For easier cases, like an epiretinal membrane or macular hole, the patient was given a retrobulbar block and kept awake. More invasive and intricate operations, like a proliferative vitreoretinopathy surgery or scleral buckle repair, meant general anesthesia.

Thanks to advanced surgical approaches, smaller, more precise tools, and improved drugs, retinal surgery today is less painful, less invasive, and more efficient. An awake-and aware surgery begins with an injection of propofol that renders the patient unconscious for 30 seconds to a minute. During that time the surgeon administers the retrobulbar block.

“You give them a little propofol while they are being monitored by the anesthesiologist and you give them the retrobulbar block and they hopefully wake up within 30 seconds,” Dr.Ober says. But those 30 to 60 seconds after injecting the propofol still pose a potential risk for the patient because the heart slows down. That’s why Dr. Calzada and his team no longer administer the drug.

“We give a little bit of versed and the majority of our patients have no trouble whatsoever,” Dr. Calzada says. “What we are trying to do is minimize the risks of the surgery as much as possible. It is a very simple goal.”

THE EXCEPTIONS

There are, however, procedures, patients, and even circumstances during surgery that ultimately require general anesthesia. For instance, essentially all of Dr. Hariprasad’s scleral buckle repair patients receive general anesthesia. Additionally, patients who cannot lay still or those who are exceptionally anxious are candidates for general anesthesia. He also anesthetizes pediatric patients under 14 years old. 

“I have done a retrobulbar block in kids who are 14 years old,” he says. “I think 14 years old for me is the cutoff.”

Dr. Ober includes 20-something men in the possible general anesthesia category because “they tend to teeter on the edge of anxiety.” And fidgeting on the table during retinal surgery could lead to disaster. Patients with mental or physical issues (congestive heart failure, back issues, a cold or cough) are also candidates for general anesthesia.

“The most common thing for me is that somebody has intractable discomfort lying still, they have back pain that doesn’t allow them to lay flat on their back,” Dr. Ober says. “That’s probably the most common reason for conversion, and it’s very rare.”

And while patients given general anesthesia “are few and far between,” those that do go to sleep are less asleep than in the past. Instead of a general endotracheal tube, he uses a laryngeal mask airway.

DIALING IT IN

Finding the sedation sweet spot in awake-and-award surgery can be tricky. Too little sedation and the patient can become either agitated or inebriated and uncooperative. The patient is conscious by the standard of consciousness, but unwilling or unable to follow reasonable commands like don’t move or talk (Dr. Calzada has had patients sing and call out from under the drape). Too much sedation and the patient falls asleep, something no eye surgeon wants because the patient can jolt awake, moving their head and eyes at the wrong moment. For that reason Dr. Calzada has a strict rule in his operating room — patients are either sedated (awake and aware) or asleep. There is no in between.

“Awake with mild sedation for anxiety is optimal,” Dr. Calzada says. “But if the patient is way too anxious where they need pretty heavy IV sedation, then in my opinion that patient goes into general anesthesia because you can control everything better. It is a matter of managing risks and expectations.”

Retinal surgeons also don’t want patients talking during surgery. Dr. Ober chats will patients while they are being prepped and draped to help relax and reassure them. He plays music in the operating room and asks patients what they would like to hear. But when surgery begins, the conversation ends.

“I make sure that they are aware they are not to talk during the surgery,” Dr. Ober says. “Even a little movement can move inside the eye and if I’m peeling a delicate membrane it can make a difference.”

Dr. Hariprasad used to play music while operating, but stopped a few years back because he felt it decreased the seriousness of the work and made the room “just a little too lighthearted.” The only sound in Dr. Hariprasad’s operating room during surgery is his voice and the clicking of the vitrectomy device. To avoid unexpected or involuntary movement, Dr. Hariprasad also tapes down the patient’s head.

“Patients understand the concept that we are working inside of their eye and that any movement can be disastrous,” he says. “If we need to speak to the patient we address them by name.”

ON THE SEDATION HORIZON

Topical anesthetics, the next iteration of sedated-and-aware surgery, are already used by some cataract surgeons. Topical anesthetics numb the eye but don’t freeze the muscles, so they seem unlikely to become a tool in the retinal surgeon’s toolbox. That’s not to say that the idea hasn’t crossed Dr. Hariprasad’s mind. For now, at least, he’s dismissed it.

“In retinal surgery, we need the eyeball to be paralyzed because we’re doing very delicate surgery on the surface of the retina,” he says. “I think we are where we need to be when using retrobulbar blocks vs general anesthesia in terms of balancing minimally invasive anesthesia with local and systemic safety.”

Like his colleague, Dr. Ober has also considered topical anesthetics for some cases. And like his colleague, he has ultimately dismissed the idea.

“For cataract surgery, you have big instruments in the eye and you can hold it fairly still,” he says. “You are not doing anything nearly as delicate as peeling the internal membrane where even the small movements can make a big difference.” RP

REFERENCE

  1. Hoffman J. Going under the knife, with eyes and ears wide open. The New York Times. March 25, 2017.