Pre-operative Starvation Times Ayngara Thillaivasan

Background Reason for pre-operative starvation is to try to prevent aspiration of stomach contents during anaesthesia.

Mendelson’s Syndrome New York Obstetrician. Face mask anaesthesia: Ether & Nitrous Oxide. Aspiration in 66 out of women. 2 Deaths from airway obstruction from solid food. Liquid aspiration lead to a syndrome of dyspnoea, cyanosis and tachycardia. (All recovered.)

Gastric Contents Volume & pH of gastric contents. Determined by oral intake, gastric secretion & emptying. Experiments in 1974: Patients at risk of aspiration pneumonitis from the presence of 25mls of residual gastric volume of pH <2.5. Entire contents would have to reach the lungs. 50% of healthy fasted people: >25ml & pH~2.

Gastric Emptying William Beaumont, American army surgeon. Canadian fur trapper with a gunshot wound to the stomach. Permanent gastric fistula. Water: Exponential process. Half life ~10 mins. 95% clear liquids gone in 1 hr. Solids: Constant. Starts 1 hr after ingestion. 50% of a meal is at the duodenum in 2hrs.

Risk Factors For Aspiration Emergency procedures. Light anaesthesia. GI pathology. Obesity. Opiods. Neurological disease. Lithotomy position. Difficult intubation. Reflux disease. Hiatus hernia.

ASA Task Force Guidelines anaesthesiologists in both private and academic practice from America and Canada. “Not intended as standards or absolute requirements.” “The guidelines provide basic recommendations that are supported by analysis of current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data.”

Guidelines (Accepted by the AAGBI.) “2-4-6 (?8) Rule”. – 2 hours for clear fluid. – 4 hours for breast milk. – 6 hours for solids and non-human milk. Preoperative assessment… Routine use of GI stimulants, gastric acid secretion blockers, antacids, antiemetics, anticholinergics, and multiple agents is NOT recommended.

Audit

Responses 158 Audit forms. – X2: No induction times. – X4: No actual starvation times. 496 cases ~ 31% X1: Cancelled. (Not starved for procedure.)

Specialties 1 SPECIALITYURGENCYORALRANGEAVERAGE Neuro/CFElect (5)Water2hr 20 – 20hr 10*5hr 24* Food14hr 0 – 16hr 014hr 53 Breast20hr 10* Urg (2)Water4hr 50 – 6hr 105hr 30 Food12hr 25 Bottle12hr 50 Card/AngioElect (11)Water2hr 0 – 14hr 04hr 39 Food7hr 30 – 15hr 2010hr 33 Breast11hr 45 Bottle8hr 15 – 8hr 308 hr 23

Specialties 2 SPECIALITYURGENCYORALRANGEAVERAGE EyesElect (16)Water2hr 0 – 7hr 403hr 41 Food8hr 10 – 17hr 2512hr 33 Breast7hr 0 – 12hr 159hr 38 Bottle6hr 0 – 10hr 58hr 1 UrologyElect (13)Water2hr 0 – 7hr 154hr 15 Food6hr 0 – 19hr 012hr 15 Breast11hr 45 Bottle8hr 10 – 8hr 258hr 18 Urg (1)Water9hr 50 Food9hr 50

Specialties 3 SPECIALITYURGENCYORALRANGEAVERAGE Gen/LiverElect (13)Water2hr 0 – 11hr 03hr 58 Food7hr 0 – 15hr 4012hr 36 Bottle6hr 5 – 6hr 306hr 18 Urg (3)Water3hr 15 – 27hr 512hr 33 Food6hr 45 – 27hr 516hr 55 T&OElect (5)Water3hr 20 – 6hr 304hr 55 Food6hr 5 – 11hr 308hr 13 Bottle8hr 10 – 8hr 508hr 30 Urg (4)Water2hr 30 – 12hr 306hr 15 Food12hr 10 – 14hr 013hr 15

Specialties 4 SPECIALITYURGENCYORALRANGEAVERAGE B&PElect (13)Water2hr 35 – 5hr 03hr 52 Food5hr 45 – 17hr 3012hr 25 Breast4hr 05 Bottle7hr 30 – 17hr 1512hr 5 Urg (5)Water4hr 15 – 6hr 105hr 24 Food12hr 10 – 15hr 2013hr 55 ENTElect (19)Water2hr 15 – 15hr 457hr 4 Food8hr 10 – 18hr 015hr 22 Urg (1)Water2hr 45 Food18hr 45

Specialties 5 SPECIALITYURGENCYORALRANGEAVERAGE MRIElective (9)Water2hr 0 – 14hr 305hr 6 Food6hr 30 18hr 1513hr 6 Breast15hr 30 Bottle14hr 0 Urgent (1)Water3hr 15 Food15hr 45 DentalElective (5)Water2hr 30 – 13hr 08hr 51 Food11hr 0 – 13hr 012hr 15 GastroElective (4)Water4hr 30 – 15hr 5011hr 21

Specialties 6 SPECIALITYURGENCYORALRANGEAVERAGE OncologyElect (16)Water2hr 40 – 16hr 07hr 18 Food12hr 50 – 21hr 016hr 5 Breast7hr 40 Bottle5hr 45 – 9hr 107hr 28 Urg (2)Water8hr 15 – 15hr 1511hr 45 Food8hr 15 – 15hr 1511hr 45

Total ORALELECTIVEURGENT WATER5hr 527hr 8 FOOD12hr 4513hr 59 BREAST9hr 8 BOTTLE10hr 412hr 50

League Table (Elective) BESTWORST WATEREyesGastro FOODT&OOncology BREASTB&PMRI BOTTLEGeneralMRI

Reasons

Lists AMPMALLDAY WATER2hr 0 – 16hr 0 Av: 6hr 33 2hr – 7hr 15 Av: 3 hr 43 2hr 0 – 14hr 0 Av: 4hr 2 FOOD8hr 15 – 21hr 0 Av: 14hr 44 6hr 5 – 19hr 0 Av: 11hr 13 5hr 45 – 16hr 0 Av: 11hr 5 BREAST4hr 5 – 15hr 30 Av: 6hr 45 11hr 45 BOTTLE5hr 45 – 17hr 15 Av: 9 hr 19 6hr 15 – 7hr 30 Av: 6hr 53 6hr 20 – 12hr 50 8hr 36

Position On List AMPMALLDAY STMIDENDSTMIDENDSTMIDEND WATER6hr 36hr 49 6hr 54 3hr 213hr 48 4hr 33 2hr 58 5hr 12 5hr 0 FOOD13hr 46 15hr 8 15hr 51 11hr 40 12hr 55 8hr 38 14hr 7 10hr 33 8hr 50 BREAST5hr 4211hr 48 11hr 45 BOTTLE7hr 4310hr 37 11hr 35 6hr 157hr 30 8hr 20 8hr 25 8 hr 46

List Changes

List Changes 2

List Changes 3 DOWNOVER RUNNING NO CHANGES UP WATER 5hr 498hr 15hr 176hr 5 FOOD 14hr 4314hr 4012hr 5313hr 45 BREAST 15hr 30 9hr 455hr 53 BOTTLE 10hr 157hr 557hr 4612hr 23

Conclusions Insufficient starvation is not a major problem. Starvation times are for the most part greatly in excess of what is needed. Slight difference between elective and urgent cases. AM lists lead to prolonged starvation times. Medical lists are worse than surgical for starvation times. Altered / overrunning lists have longer starvation times.

Recommendations Limited for prehospital. – Make sure parents understand. – Encourage them to follow as fully as possible. – ?Anaesthetic information? Discuss with teams. Early & realistic decisions when lists are changing/overrunning. ONCOLOGY.