In Part I, I discussed the importance of preoperative preparation, including a detailed medical history to insure a safe surgical experience. (See Fall 2014 issue) In this piece, I will cover the specific medications used with anesthesia, how they are used together to achieve the goals for a particular operation, and finally a discussion of aspects of post-operative management.
In Part I, I discussed the importance of preoperative preparation, including a detailed medical history to insure a safe surgical experience. (See Fall 2014 issue) In this piece, I will cover the specific medications used with anesthesia, how they are used together to achieve the goals for a particular operation, and finally a discussion of aspects of post-operative management. The focus will be on cataract surgery since it is the number-one ocular surgical procedure with over 3.54 million surgeries performed in 2013.1
As reimbursements have declined, surgeons and ambulatory surgery centers (ASCs) have looked to become more efficient while maintaining a high level of care and safety. Benchmarking or comparing yourself to other ASCs is a useful tool. Table 1 is from the Institute for Quality Improvement, part of the Accreditation Association for Ambulatory Health Care (AAAHC), a certifying organization for outpatient surgical centers.2 Participating ASCs submit specific case data and detailed information concerning their surgical center to give a large database of accredited surgical centers. As Table 1 shows, the average cataract surgery patient is in the ASC for only about two hours from start to finish. To be able to achieve this goal, all members of the ASC team have had to refine their techniques to become more efficient. Anesthesia must have the patient comfortable enough for the procedure but alert enough to be discharged within a relatively short time.
In years past, cataract surgery was performed either with general anesthesia or retrobulbar injection, frequently combined with facial blocks. Table 2 shows that topical is now preferred the vast majority of the time with oral medication, peribulbar, and retrobulbar anesthesias lagging far behind.2 This same study reports that 82 percent of patients receive IV sedation. There are a number of options for IV sedation. I have surveyed the attendees of my 2014 American Society of Cataract and Refractive Surgery (ASCRS) course about what technicians and nurses need to know about anesthesia. The vast majority of the attendees were operating room technicians or nurses, and they have insight into the anesthesia techniques of their particular ASC. The top three medications that the respondees listed were midazolam (Versed, Roche), fentanyl (Sublimaze, Janssen-Cilag), and propofol (Diprivan, AstraZeneca). These three medications in various combinations represented 97 percent of the medications used in ASCs for IV sedation. The common factor was that midazolam, alone or in combination, was the medication of choice 85 percent of the time.
Even though these studies show what is preferred the vast majority of the time, the surgeon and anesthesia staff need to adapt to the needs of the patient. In my own surgical center, I will use IV sedation in combination with topical and intracameral anesthesia most of the time. However, there are times, particularly with younger, more anxious individuals, who will need to have propofol sedation in combination with retrobulbar injection. This goes back to the pre-operative assessment in which the technician may have recognized concerns that would limit the use of topical anesthesia, for example, a patient with mild Alzheimer’s, hearing impairment, or language barrier.
Midazolam is a benzodiazepine, related to Valium (diazepam, Roche). It is an anti-anxiety, amnestic medication of relatively short half-life that makes it a wonderful medication for outpatient procedures when the patient often arrives anxious. It relieves anxiety but generally allows the patient to remain awake and somewhat alert through the procedure. Midazolam does not offer pain relief, and, for situations requiring pain control, fentanyl is commonly used.
Fentanyl is a narcotic of relatively short duration. Fentanyl, like all narcotics, is intended for pain relief but does not relieve anxiety, which is why midazolam and fentanyl are frequently given together. Like all narcotics, it can also be associated with respiratory depression as well as post-op nausea and vomiting.
The last of the three most commonly prescribed medications is propofol. It is considered a general anesthetic and as such must be administered by someone skilled in anesthesia. It has a rapid onset, has a very short duration, offers excellent pain relief, and is antiemetic. The patient may actually feel somewhat euphoric following his propofol sedation.
Once the patient is sedated, most will need some form of local anesthesia. With retrobulbar, the anesthetic is injected behind the globe within the muscle cone using a special needle. It may be preferred where no motion of the globe is needed, such as for macular surgery cases. Retrobulbar anesthesia provides pain relief and limits the motion of the globe but may have a higher risk of complications, such as damage to the globe itself or hemorrhage behind the globe. Peribulbar is a local anesthetic given outside the muscle cone and is generally thought to be safer than retrobulbar. It generally offers excellent pain relief, but there may still be some motion of the globe.
Topical may be any of the commercially available drops such as tetracaine (TetraVisc, OCuSOFT), proparacaine (Alcaine, Alcon), lidocaine (Xylocaine, Hospira) for injection, or even lidocaine preparation specially made for the eye in a gel form (Xylocaine 2% Jelly, AstraZeneca). This is usually given into the conjunctiva either in the pre-op area or in the operating room immediately prior to surgery. Although there are a number of options available for topical anesthesia, several studies have shown that they are all equally effective.3,4 Topical can give good conjunctival anesthesia, but eye movement is still present, which is usually acceptable with cataract surgery but limits its use in retinal surgery. Intraocular lidocaine may be used at the start of cataract surgery for additional anesthesia. Intraocular lidocaine 1% must be non-preserved, methylparaben free (MPF) to avoid corneal toxicity. It has been shown to relieve intraocular pain but again does not restrict eye movement.5
The goal of anesthesia is to provide adequate levels of anxiolysis and pain relief with rapid return to alertness and stable vital signs. A successful anesthesia experience does not end with the operation. Individuals may experience post-operative pain or nausea and vomiting which may require extra care, delaying their discharge from the recovery area. Individuals at particular increased risk for post-operative nausea and vomiting (PONV) include females, obese individuals, non-smokers, strabismus surgery patients, and longer surgery such as in some retinal or plastic cases.6
Although PONV is fairly uncommon, each ASC should have its own protocol for management of PONV. First is the recognition of the risk factors prior to surgery in considering these individuals for pre-treatment. More commonly, especially with cataract surgery, it may not be possible to recognize who will develop PONV. There are five general classes of medications that are commonly used for PONV. Of these, the serotonin antagonists, such as ondansetron (Zofran, GlaxoSmithKline), are probably the most commonly used. Other choices include steroids such as dexamethasone, antihistamines such as promethazine (Phenergan, Sanofi-Aventis), or dopamine antagonists (metoclopramide, Reglan, Ani). Scopolamine (Transderm Scop, Novartis), which is an anticholinergic, is often used as a patch at the time of surgery in high-risk individuals. Most anesthesia providers will have a continuum of care to achieve the most optimal results for the more rapid discharge of the PONV patient.
The final step in the procedure is the patient’s discharge and discharge instructions. The discharge is ultimately the responsibility of the surgeon working with the RN in the recovery area. However, the ASC technician may be the one who provides the final one-on-one instructions to the patient and his or her family. The technician working under the supervision of the RN should be able to make the patient aware of what to expect in the immediate post-op period and provide written instructions for post-op medications and follow up.
The success of surgery and often the patient’s perception of success depend on a smooth and uneventful anesthesia experience. As discussed in Part I, it starts in the clinic with a detailed history of medical problems, medications used, and allergies. It continues with the recognition of patient personality and concerns, including having the technician convey this information to the surgery and anesthesia personnel.
In the ASC, all personnel-not just anesthesia personnel-should have an understanding of the intended effects and potential side effects of all medications. The technician should understand the importance of post-op monitoring to make sure that the patient is stable enough for discharge and that the patient has a clear understanding of the home instructions. Although surgery is ultimately the responsibility of the physician, the technician may be the first and the last member of the ophthalmic/ASC team to work with the surgery patient. The technician has an important role in insuring a successful surgery and a pleasant experience for the patient.
1. Market Scope. September 30, 2014.
2. AAAHC Institute for Quality Improvement, July-December 2013 Report.
3. Amiel H, Koch P. Tetracaine hydrochloride 0.5% versus lidocaine 2% jelly as a topical anesthetic agent in cataract surgery: comparative clinical trial. J Cataract Refract Surg. 2007 Jan;33(1):98-100.
4. Davis, MJ, Pollack JS, Shott S. Comparison of topical anesthetics for intravitreal injections: a randomized clinical trial. Retina. 2012 Apr;32(4):701-5.
5. Ophthalmology, Vol. 115; #3, March 2008.
6. Hosp. Pharmacy, Vol. 40, Issue 7, July 2005.