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

1946. New York Obstetrician. Face mask anaesthesia: Ether & Nitrous Oxide.

Aspiration in 66 out of 44016 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 1999.

10 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

SPECIALITY URGENCY ORAL RANGE AVERAGE

Neuro/CF Elect (5) Water 2hr 20 – 20hr 10* 5hr 24*

Food 14hr 0 – 16hr 0 14hr 53

Breast 20hr 10*

Urg (2) Water 4hr 50 – 6hr 10 5hr 30

Food 12hr 25

Bottle 12hr 50

Card/Angio Elect (11) Water 2hr 0 – 14hr 0 4hr 39

Food 7hr 30 – 15hr 20 10hr 33

Breast 11hr 45

Bottle 8hr 15 – 8hr 30 8 hr 23

Specialties 2

SPECIALITY URGENCY ORAL RANGE AVERAGE

Eyes Elect (16) Water 2hr 0 – 7hr 40 3hr 41

Food 8hr 10 – 17hr 25 12hr 33

Breast 7hr 0 – 12hr 15 9hr 38

Bottle 6hr 0 – 10hr 5 8hr 1

Urology Elect (13) Water 2hr 0 – 7hr 15 4hr 15

Food 6hr 0 – 19hr 0 12hr 15

Breast 11hr 45

Bottle 8hr 10 – 8hr 25 8hr 18

Urg (1) Water 9hr 50

Food 9hr 50

Specialties 3

SPECIALITY URGENCY ORAL RANGE AVERAGE

Gen/Liver Elect (13) Water 2hr 0 – 11hr 0 3hr 58

Food 7hr 0 – 15hr 40 12hr 36

Bottle 6hr 5 – 6hr 30 6hr 18

Urg (3) Water 3hr 15 – 27hr 5 12hr 33

Food 6hr 45 – 27hr 5 16hr 55

T&O Elect (5) Water 3hr 20 – 6hr 30 4hr 55

Food 6hr 5 – 11hr 30 8hr 13

Bottle 8hr 10 – 8hr 50 8hr 30

Urg (4) Water 2hr 30 – 12hr 30 6hr 15

Food 12hr 10 – 14hr 0 13hr 15

Specialties 4

SPECIALITY URGENCY ORAL RANGE AVERAGE

B&P Elect (13) Water 2hr 35 – 5hr 0 3hr 52

Food 5hr 45 – 17hr 30 12hr 25

Breast 4hr 05

Bottle 7hr 30 – 17hr 15 12hr 5

Urg (5) Water 4hr 15 – 6hr 10 5hr 24

Food 12hr 10 – 15hr 20 13hr 55

ENT Elect (19) Water 2hr 15 – 15hr 45 7hr 4

Food 8hr 10 – 18hr 0 15hr 22

Urg (1) Water 2hr 45

Food 18hr 45

Specialties 5

SPECIALITY URGENCY ORAL RANGE AVERAGE

MRI Elective (9) Water 2hr 0 – 14hr 30 5hr 6

Food 6hr 30 18hr 15 13hr 6

Breast 15hr 30

Bottle 14hr 0

Urgent (1) Water 3hr 15

Food 15hr 45

Dental Elective (5) Water 2hr 30 – 13hr 0 8hr 51

Food 11hr 0 – 13hr 0 12hr 15

Gastro Elective (4) Water 4hr 30 – 15hr 50 11hr 21

Specialties 6

SPECIALITY URGENCY ORAL RANGE AVERAGE

Oncology Elect (16) Water 2hr 40 – 16hr 0 7hr 18

Food 12hr 50 – 21hr 0 16hr 5

Breast 7hr 40

Bottle 5hr 45 – 9hr 10 7hr 28

Urg (2) Water 8hr 15 – 15hr 15 11hr 45

Food 8hr 15 – 15hr 15 11hr 45

Total

ORAL ELECTIVE URGENT

WATER 5hr 52 7hr 8

FOOD 12hr 45 13hr 59

BREAST 9hr 8

BOTTLE 10hr 4 12hr 50

League Table (Elective)

BEST WORST

WATER Eyes Gastro

FOOD T&O Oncology

BREAST B&P MRI

BOTTLE General MRI

Reasons

3

11

3

4

3

8

0 2 4 6 8 10 12

1

Bed too early

Awake too late

Didn't want anything inmorining

Didn't understand/adhere toinstructions

Prolongued NBM

Other

Lists

AM PM ALLDAY

WATER 2hr 0 – 16hr 0

Av: 6hr 33

2hr – 7hr 15

Av: 3 hr 43

2hr 0 – 14hr 0

Av: 4hr 2

FOOD 8hr 15 – 21hr 0

Av: 14hr 44

6hr 5 – 19hr 0

Av: 11hr 13

5hr 45 – 16hr 0

Av: 11hr 5

BREAST 4hr 5 – 15hr 30

Av: 6hr 45

11hr 45

BOTTLE 5hr 45 – 17hr 15

Av: 9 hr 19

6hr 15 – 7hr 30

Av: 6hr 53

6hr 20 – 12hr 50

8hr 36

Position On List

AM PM ALLDAY

ST MID END ST MID END ST MID END

WATER 6hr 3 6hr 49

6hr 54

3hr 21 3hr 48

4hr 33

2hr 58

5hr 12

5hr 0

FOOD 13hr 46

15hr 8

15hr 51

11hr 40

12hr55

8hr 38

14hr 7

10hr 33

8hr 50

BREAST 5hr 42 11hr 48

11hr 45

11hr 45

BOTTLE 7hr 43 10hr 37

11hr 35

6hr 15 7hr 30

8hr 20

8hr 25

8 hr 46

List Changes

107

14

20

1

8

2

10

No Change

No Order

Up

Cancelled

Down

Insufficient Starvation

List Changes 2

42

1 13

1

43

1

1

12

2

1

12

5 11

2

6

1

1

0

2

4

6

8

10

12

Cardiol

ogy

Dental

ENT

Gastro

Gener

alM

RI

Neuro

Oncolo

gy

Ophth

almolog

y

Plastic

s

Urolog

y

Overrunning

Down

Up

List Changes 3

DOWN OVER

RUNNING

NO CHANGES

UP

WATER 5hr 49 8hr 1 5hr 17 6hr 5

FOOD 14hr 43 14hr 40 12hr 53 13hr 45

BREAST 15hr 30 15hr 30 9hr 45 5hr 53

BOTTLE 10hr 15 7hr 55 7hr 46 12hr 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.