Preoperative fasting for ambulatory cataract surgery: a systematic review

Methodological quality of the review: Low confidence

Authors: Popovic M, Schlenker MB, Goldshtein D, Rai A, El-Defrawy S.

Region: United Kingdom (UK) and Canada

Sector: Service delivery

Subsector: Quality of clinical care

Equity focus: Not stated

Review type: Other review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:
Preoperative fasting before surgery is the common practice of abstinence from the oral intake of all liquids and solids, thus aiming to prevent aspiration pneumonitis following the induction of anesthesia. This long-standing practice was widely adopted after it was shown that anesthesia increases the risk of aspiration due to reduced lower esophageal sphincter tone and decreased level of consciousness with resultant loss of protective reflexes.

Objectives:
Investigate the optimal duration of preoperative fasting in cataract surgery.

Main findings:
A total of six studies were included in the review, where three were case reports, and one each was a retrospective review, physician survey and editorial. Four studies came from the UK, while the other two studies were published in Canada. In general, anesthesia techniques, agents and sedative choices were variable across included studies.

Two studies found no cases of aspiration in over 35,000 patients who underwent cataract surgery without preoperative fasting, some with intravenous sedation (50% in one series, less than 1% in the second). A survey of the British Ophthalmic Anaesthesia Society found that over 50% of centres did not require fasting before cataract surgery. Only one included report discussed a case of aspiration pneumonitis following cataract surgery with general anesthesia and 14 hours of preoperative fasting. In closing, further evidence is needed to delineate the risk of pulmonary aspiration based on fasting time in cataract surgery.

Methodology:
A systematic search of the literature was conducted on Ovid MEDLINE (1946 to 12 December, 2017) to identify relevant studies. The reference lists of included studies were reviewed to identify further relevant studies. Any article, irrespective of study design discussing the duration of preoperative fasting before cataract surgery, was included.

An independent screening process was conducted by two authors. First, the titles and abstracts of search studies were screened to identify eligible studies. Afterwards, full text screening was conducted and studies meeting all eligibility criteria were included. Consensus of both authors was used to resolve all disagreements in screening.

The following information was extracted from included studies: number of eyes, study design, country of origin, length of follow-up, duration of preoperative fasting, anesthetic regimen, sedative regimen, patient satisfaction with anesthesia, and the incidence of aspiration. Last follow-up was used in the collection of all postoperative outcomes. Descriptive statistics, such as percentages, were used to present the collected data.

Applicability/external validity:
Authors did not discuss the applicability/external validity of findings.

Geographic focus:
Authors include studies from the UK and Canada. Authors do not discuss applicability of findings to low and middle income countries.

Summary of quality assessment:
Overall, low confidence was attributed to the conclusions about the effects of this study. Authors did not conduct a thorough search of the literature to ensure that all relevant studies were identified, impacting on study validity. Quality assessment of included studies was not conducted, therefore it is not clear which study had low or high risk of bias impacting on findings reliability.