Starving Patients Before Cataract Surgery Under Regional Anesthesia: Needed or Not?

The importance of selective starvation or fasting before general anesthesia has been recognized since the 19th century. In 1882, Sir Joseph Lister stated “While it’s desirable that there should be no solid matter in the stomach when chloroform is administered, it will be found very salutary to give a cup of tea or beef-tea about two hours previously.”1 The American Society of Anesthesiologists preoperative fasting guidelines recommend a minimum fast of 2 hours for clear liquids and 6 hours for a light meal or nonhuman milk.2 These recommendations are for elective procedures requiring general anesthesia, regional anesthesia, and procedural sedation and analgesia. However, this ubiquitous practice of preoperative starvation, with near-religious adherence, is not supported by a high level of evidence from prospective clinical trials.3 In fact, the American College of Emergency Physicians’ clinical policy on procedural sedation and analgesia states “preprocedural fasting for any duration has not demonstrated a reduction in the risk of emesis or aspiration when administering procedural sedation and analgesia.”4 It is further stated that a combination of propofol and ketamine can be safely administered for procedural sedation and analgesia in unfasted patients without increase in the risk of regurgitation and aspiration.4 Thus, the need for preoperative fasting in patients undergoing cataract surgery under regional anesthesia with minimal or no sedation remains controversial. This open mind article explores if there is evidence that supports obviating the need for starvation in routine cataract surgery under regional anesthesia. REASONS FOR FASTING BEFORE CATARACT SURGERY UNDER REGIONAL ANESTHESIA Perhaps the most common reason for fasting in a patient undergoing cataract surgery under regional anesthesia is that intravenous (IV) moderate sedation may be administered. Deeper levels of sedation are used sometimes for cataract surgery to increase patients’ satisfaction and acceptance. Other reasons for fasting include a possible need for deep sedation or even conversion to general anesthesia during the surgery for uncooperative patients. Also, older patients may have several comorbidities (eg, gastroesophageal reflux disease, diabetes mellitus, renal dysfunction, and hiatus hernia) and laying them flat during surgery may increase the risk of regurgitation and aspiration. Rarely, patients for cataract surgery under regional anesthesia with or without sedation may require airway manipulation as part of perioperative resuscitation efforts (eg, complications from ophthalmic blocks such as brainstem anesthesia, anaphylaxis, or cardiovascular, respiratory, endocrine, or neurological crisis).5 Preoperative omission of starvation may put these patients at risk of pulmonary aspiration during ventilation and airway intubation attempts. Operational issues and operating room efficiency may play a role in choosing a recommended fasting time. Cataract surgeries are often short duration procedures with a busy daily schedule. Frequent modifications to the lists may occur from last-minute surgery postponement. Therefore, longer fasting times may be perceived as logistically favorable as these patients may be moved into available slots. CONSEQUENCES OF FASTING, PARTICULARLY IN THE ELDERLY Prolonged fasting affects patients’ physical and psychological well-being and contributes to adverse effects such as dehydration, hypovolemia, hypotension, irritability, headache, emesis, and hypoglycemia. Dehydration from fasting can enhance pain response leading to significant discomfort and need for analgesia.6 Anxiety is exacerbated by hunger, thirst, and a dry mouth.7 Fasting may also induce stress responses that may increase insulin resistance and catabolism.8 Some patients believe fasting also entails not taking medications; this may lead to perioperative uncontrolled hypertension, hyperglycemia, and major adverse cardiovascular events. Patients usually do not like fasting, which may influence patient satisfaction. WHAT ARE THE CONSEQUENCES OF ASPIRATION? The risk of pulmonary aspiration of gastric contents, even with general anesthesia, is very low—approximately 1 in 10,000 of elective adult surgeries.9 Although the outcomes after potential aspiration are highly variable, in most cases, the severe consequences of aspiration are few. A French study reported death from pulmonary aspiration under general anesthesia of 1/75,500.10 Another study reported an incidence of aspiration of 1/75,487; however, no aspiration occurred in cases performed under regional anesthesia.11 A large 4-year retrospective study in a nonobstetric American university-affiliated adult hospital of almost 100,000 anesthesiology-led anesthetics revealed that 4 of 26,434 patients (0.015%) who received monitored anesthesia care were labeled as being complicated by pulmonary aspiration.12 None of these 4 cases of pulmonary aspiration were in ophthalmology patients. A comprehensive qualitative systematic review addressed the magnitude of pulmonary aspiration during procedural sedation by both anesthesiologists and nonanesthesiologists.13 The study concluded that outside of gastrointestinal endoscopy, the incidence of aspiration during procedural sedation is rare, idiosyncratic, and typically benign. Predictive risk factors identified were underlying illness, higher American Society of Anesthesiologists physical status, and deep sedation. Thirty-four instances of nonendoscopy aspiration were reported—none of which pertained to sedation and cataract surgery nor noncompliance to nil-per-os guidelines.13 The authors concluded that although fasting is widely regarded as essential to mitigate aspiration risk, they failed to identify any relationship between fasting and aspiration,13 thus calling into question the need to adhere to general anesthesia fasting guidelines for moderate sedation. A Cochrane review of available evidence concluded that there was lack of evidence to suggest that a shorter duration of fasting would increase the risk of aspiration, regurgitation, or related morbidity compared with the standard practice of fasting after midnight.14 Interestingly, although it is commonly assumed that protein consumption (eg, milk) might delay gastric emptying, a study in healthy adults found no difference in gastric emptying after drinking tea with or without 50 mL milk.15 In fact, consumption of water before surgery might enhance gastric emptying and significantly reduces gastric volume.16 A recent large study (n = 11,500) found that liberal consumption of clear liquids before induction of anesthesia reduced postoperative nausea and vomiting.17 Another current study concluded that allowing liberal intake of clear liquids until the patient is taken to the operating room (ie, implementation of the 6-4-0 fasting regimen) reduced the median fluid fasting duration without any complications.18 These may be the reasons for differences in preoperative fasting practices around the world.7,19,20 IS FASTING NECESSARY IN PATIENTS UNDERGOING CATARACT SURGERY UNDER REGIONAL ANESTHESIA? The modern phacoemulsification self-sealing incision surgery has greatly improved control of the wound and anterior chamber, thus reducing the need for total akinesia during cataract surgery. There has been a major change in provision of anesthesia for cataract surgery over the past 2 decades, with a decrease in usage of general anesthesia and increasing use of local anesthesia.21 A recent study in the United Kingdom involving 357,000 cataract surgeries found that techniques of local and regional anesthesia comprised 8.8% peribulbar, 1.3% retrobulbar, 50.5% sub-Tenon’s, 1.4% subconjunctival, 13.8% topical, and 24.2% topical-intracameral, of these, only 4.3% of patients received sedation.21 Many ophthalmologists consider globe akinesia no longer mandatory, and some perceive that a mobile eye can actually assist with safe and efficient surgery, thus there may be no need for invasive eye blocks.22 The pain associated with the administration of regional anesthesia for cataract surgery is generally very low, thus sedation is unnecessary or undesirable during the administration of block.23 In many places around the world, patients are not fasted before “routine” cataract surgery under regional anesthesia. Cataract surgery takes place in some centers without the presence of an anesthesiologist, meaning that “conversion” to IV sedation or general anesthesia is not a possibility.16 In the context of cataract surgery, what can be gleaned from the existing published literature to guide best practice? Maltby and Hamilton24 from Calgary in Canada published a correspondence detailing their experience citing 30,000 cataract surgeries without dietary restrictions and fasting before cataract surgery (without heavy sedation or general anesthesia). There were no reported adverse outcomes from this practice. Another study from Vancouver documented 5123 cataract surgeries performed without fasting over a 1-year period (April 2007–March 2008).25 Approximately 50% received IV sedation and 3% required peribulbar or retrobulbar blocks. No recognized adverse events of aspiration or pneumonia were reported.25 Another case series of nearly 7000 consecutive phacoemulsification under topical/intracameral local anesthesia in patients who did not fast and <1% receiving (oral) anxiolytic reported no adverse events.16 GUIDELINES ON FASTING FOR CATARACT SURGERY Several national and international associations have provided guidance on fasting before cataract surgery under regional anesthesia. As far as we are aware, the only national guideline dedicated to ophthalmic local/regional anesthesia including fasting is the UK publication, promulgated jointly by the Royal College of Anaesthetists and the Royal College of Ophthalmologists.26 The UK guidelines are more liberal than many others. The second edition published in 2001 stated that “Although there are theoretical reasons for believing that a period of fasting prior to local anesthesia might be appropriate…, a survey of members of the British Ophthalmic Anesthesia Society showed that almost 65% of its members did not restrict fluid or food intake indeed many cited the undesirable effects of thirst, nausea, and the possibility of hypoglycemia as reasons for allowing oral intake.”7 The authors concluded that there were “differences in the clinical practices of individual [anesthesiologist]. The majority do not consider that it is necessary for patients to be fasted prior to regional anesthesia for eye surgery.”7 The UK national guideline published in 2012 superseded the previous versions.26 It states that “there have been no reported cases of aspiration under local anesthesia during cataract operations. If sedation is to be additionally administered, the patients may need to be fasted in accordance with the local protocols. Starvation is generally not necessary for minimal sedation. However, when moderate or deep sedation is planned, the patient must be fasted and fully prepared as for general anesthesia.” The recommendation concluded that it was unnecessary for patients to be fasted before regional anesthesia for eye surgery without sedation, though it was acknowledged that there was an absence of directly applicable clinical studies of good quality to support this recommendation.26 In the United Kingdom, the 2010 national cataract surgery guideline27 cites the UK guideline above, and states that “it is unnecessary to fast patients for cataract surgery under regional anesthesia but they should not have a full stomach immediately beforehand because of the risk of vomiting during the procedure.” The 2017 national guideline Cataracts in Adults: Management Produced by the National Institute for Healthcare Excellence discusses local anesthesia technique in general, but does not mention fasting.28 Other countries may have their own guidelines, though some have not been updated for more than a decade. More recent cataract guidelines in English include Preferred Practice Pattern Guidelines of the American Academy of Ophthalmology (2016).21 This document has a section on anesthesia, but does not discuss fasting. The 2016 Preferred Practice Pattern from the Royal Australian and New Zealand College of Ophthalmologists29 mentions anesthesia only briefly, and does not discuss fasting. The Canadian Ophthalmological Society’s Cataract Guidelines 200830 cites the 2006 guidance from the Canadian Anesthesiologists’ Society: “for all types of anaesthesia, [they] recommend a 2-hour fast after clear fluid intake and a 6-hour fast after a light meal of clear fluids and toast… Anesthesia guidelines are aimed at eliminating the risk of aspiration, which is only present when drugs that interfere with an individual’s basic protective reflexes have been administered. If topical anesthesia is administered, without IV opioid or hypnotic-sedative, fasting is not necessary. At the present time, there is no uniform policy in Canada with regard to fasting for cataract surgery involving IV sedation or infiltration anesthesia.” With the lack of international professional consensus on the matter, local practices based on institutional recommendations should be respected. SUMMARY The lack of consensus with regards to fasting in patients undergoing cataract surgery under regional anesthesia has resulted in significant dissimilarity in practices in different institutions around the world. The benefits of avoiding preoperative fasting in routine cataract surgery under regional anesthesia outweigh the significantly low risk and consequences for pulmonary aspiration. Current evidence suggests that we take a more liberal approach with respect to preoperative fasting in patients undergoing cataract surgery under regional anesthesia with no sedation or minimal sedation. Patients at low risk of aspiration and those less likely to require sedation or conversion to general anesthesia should be allowed to consume a light meal (eg, tea and toast) or liquids (eg, carbohydrate and/or electrolyte drink) before surgery. Such practice should prevent preoperative thirst and hunger and improve patient well-being and satisfaction. More research is clearly desirable before firm recommendations can be made. DISCLOSURES Name: Edwin Seet, MBBS, Mmed. Contribution: This author helped with the concept and design of this manuscript, drafting the article, and revising it critically. Conflicts of Interest: None. Name: Chandra M. Kumar, MBBS, FFARCS, MSc, FRCA, EDRA. Contribution: This author helped with the concept and design of this manuscript, drafting the article, and revising it critically. Conflicts of Interest: None. Name: Tom Eke, MA, MD, FRCOphth. Contribution: This author helped with the concept and design of this manuscript, drafting the article, and revising it critically. Conflicts of Interest: None. Name: Girish P. Joshi, MBBS, MD, FFARCSI. Contribution: This author helped with the concept and design of this manuscript, drafting the article, and revising it critically. Conflicts of Interest: G. P. Joshi has received honoraria from Pacira Pharmaceuticals, Baxter Pharmaceuticals, Mallinckrodt Pharmaceuticals, and Merck Pharmaceuticals. This manuscript was handled by: Richard C. Prielipp, MD, MBA.

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