Preoperative Fasting for Ambulatory Cataract Surgery: A Time-Interrupted Prospective Study

The current standard for cataract surgery is phacoemulsification with intraocular lens (IOL) implantation. In this procedure, topical anesthesia has become favoured over local anesthetic blocks due to potential serious complications resulting from retrobulbar or peribulbar anesthesia. Routinely, intravenous sedation is used to supplement the topical anesthesia. If patients are not fasted, there is the potential to reduce preoperative discomfort and anxiety, ultimately improving the satisfaction with the care received. An additional benefit is that liberal fasting policies allow for flexibility in the scheduling of cases, particularly for urgent or semi-urgent situations. Clinical practice guidelines for cataract surgery published by the Canadian Ophthalmological Society (COS) recommend that fasting is unnecessary if only topical anesthesia is used without intravenous (IV) opiates or sedation. In general, these suggestions are in agreement with guidelines from the United Kingdom's Royal College of Ophthalmologists, who note that "it is unnecessary to fast patients for local anesthetic cataract surgery." According to the CAS practice guidelines, the same fasting restrictions are applied when IV sedation or anesthesia with peripheral nerve blocks (e.g. retrobulbar or peribulbar blocks) are administered. At our centre at the Kensington Eye Institute (KEI) in Toronto, Canada, almost all cataract patients receive fentanyl and midazolam, with propofol given only in rare circumstances with close observation.

This research project at the Kensington Eye Institute will consist of two phases, namely a prospective, consecutive observational analysis and a prospective time-interrupted study. In the first phase, an observational analysis will be conducted in which consecutive cataract surgery patients will be surveyed with a validated questionnaire to assess their satisfaction. Inclusion criteria will include any cataract patient scheduled for surgery who is willing and able to participate in the study, with fully informed consent provided.

Previously published literature has evaluated the use of a patient satisfaction questionnaire regarding preoperative fasting, which includes items on hunger, thirst, hoarseness of voice, difficulty breathing, pain, agitation, anxiety, nausea, vomiting, shivering and problems with concentration. A Research Assistant will complete the questionnaire with all patients preoperatively at KEI, as well as a baseline demographic checklist that will include the patient's age, gender, laterality, surgeon, length of time fasted for solids and clear liquids, as well as the type and amount of solids and liquids. Secondary endpoints will be collected postoperatively and will include the incidence of aspiration, nausea and vomiting, as well as the rate of cancellations of surgeries directly related to issues with fasting guidelines. The first phase of the study will be used to conduct an appropriate sample size calculation, which will ensure that our second phase is not underpowered for the primary efficacy endpoint.

In the second phase, a time-interrupted prospective study will be established with the following two arms: (1) experimental arm: patients will be encouraged by the Research Assistant to drink clear fluids right up to the 2 hour limit as specified in the latest ASA and CAS guidelines, with no intervention applied for solids, and (2): control arm: standard of care without any encouragement to drink clear fluids up to the 2 hour limit. Patients will be assigned to groups based on month, so that the first month of study execution will enroll all patients into the experimental arm, the second month will enroll only into the control arm, and that subsequent months will alternate enrollment in a similar method.

Given the design, the study will be in accordance with the latest ASA and CAS preoperative fasting guidelines, and will not involve any use of financial or other methods of coercion to incentivize patients that are randomly assigned to the experimental arm. The encouragement process will only involve the Research Assistant asking and encouraging the patient to drink a standardized quantity of clear fluid (up to 400mL of water, coffee, tea, apple or cranberry juice and maximum of 2 teaspoons of sugar) up to the ASA and CAS mandated guideline of 2 hours preoperatively, with the patient making the final determination of whether to comply. Following the encouragement process, a demographics and satisfaction questionnaire will be administered to each patient preoperatively, as well as another satisfaction questionnaire administered following the surgery. Baseline demographics, primary and secondary endpoints will remain consistent with the first phase.