Table 1.

Summary of extraction articles

Year	Country	Type of study	Study population	Key findings	Ref
Caffeine in the intensive care unit
Caffeine withdrawal and administration on the incidence of postoperative headache or delirium
2015	USA	Prospective survey	25 intensive care units across 17 institutions	Caffeine intake minimisation was used in 32% of intensive care units as a pharmacological method to reduce delirium	21
Caffeine withdrawal and administration on induction and emergence from sedation
2017	Iran	Prospective RCT	80 patients; 40 coffee, 40 placebo	3.5 g coffee given via nasogastric tube in the mechanically ventilated patients increases the spontaneous respiratory rate and tidal volume but does not significantly affect other respiratory indicators.	22
Safety and changes associated with caffeine administration
1987	Germany	Prospective observational	12 male patients	Quinolones can inhibit the metabolism of caffeine and may cause higher levels of circulating caffeine and side effects	23
1995	Spain	Prospective cohort	Liver impaired 33; normal liver 40	healthy individuals metabolise 3 mg IV caffeine faster than those with liver disease	24
Caffeine in the perioperative period
Caffeine withdrawal and administration on the incidence of postoperative headache or delirium
2017	Greece	Prospective cohort	446 elective surgery patients	In patients with no previous history of headache, caffeine consumption was an additional independent factor for postoperative headache	25
1994	Denmark	Prospective observational	219 elective patients	The risk of postoperative headache was significantly greater in individuals with a daily caffeine intake > 400 mg/day	26
2003	United Kingdom	Prospective observational	208 day-casepatients	Caffeine is not a risk factor for perioperative headache	27
1989	New Zealand	Prospective survey	150 day-case patients	Patient who consume > 200 mg caffeine/day were 3-fold more likely to have a headache postoperatively compared to those who did not	28
1990	Netherlands	Prospective survey	334 GA + 75 LA	There was no difference between incidence of headache between GA or LA alone. Caffeine intake was not a risk factor for developing headache postoperatively.	29
1991	New Zealand	Prospective survey	287 patients undergoing minor elective surgery	postoperative headache is related to caffeine intake and that this relationship is explained at least in part, by a perioperative caffeine withdrawal syndrome	30
1993	USA	Prospective survey	233 surgical outpatients	Among daily caffeine drinkers, those who drank caffeinated beverages on the day of the surgical procedure had a lower incidence of postoperative headaches than did those who abstained (17% versus 28%; P < 0.04)	31
1994	Switzerland	Case report	Elective open abdominal surgery for oophorectomy	28F with postoperative headache, hemihypaesthesia, cerebral oedema on CT-Head which resolved with caffeine/ergometrine	32
1995	Switzerland	Prospective RCT	40 patients; 20 caffeine, 20 placebo	Surgical patients who have high caffeine intake were randomised to taking oral caffeine tablets or placebo. No patients on caffeine supplements develop headaches while 10 (50%) on placebo developed headaches which lasted up to 7 days.	33
1997	USA	Prospective RCT	234 elective surgical patients	prophylactic postoperative 200 mg IV caffeine decreased the incidence of headache	34
Caffeine withdrawal and administration on induction and emergence from anaesthesia
2019	United Kingdom	Prospective observational	40 ASA 1 individuals	high daily caffeine intake is associated with lower propofol requirements for induction. We hypothesise that those with high daily caffeine intake have lower arousal levels before surgery, because of a relative caffeine deficit secondary to being nil-by-mouth	39
1984	USA	Prospective RCT	60 patients undergoing CABG	Patients who drank > 3 cups of coffee/day, smoke > 40 cigarettes/day and drank 1–3 oz of alcohol required more fentanyl at induction for their CABG operation	40
1984	Australia	Prospective observational	23 patients + 23 controls	High caffeine intake resulted in worse cognitive functioning post anaesthetic compared to low caffeine intake	46
2011	USA	Case report	Elective tumour resection	The use of 500 mg IV caffeine intraoperatively to ensure the patient is responsive enough to perform intraoperative language mapping. Frequent stimulation-induced seizures thereafter limited further testing.	41
2017	USA	Case report	Elective dental procedure	Use of 60 mg IV caffeine in an 16yo male with trisomy 10 with a history of slow emergence from anaesthesia to speed up emergence from anaesthesia and as a respiratory stimulant	42
2010	Egypt	Prospective RCT	60 patients 30 caffeine, 30 control	Administration of 500 mg IV caffeine decreases the number of patients who developed adverse post extubation respiratory events and hastens recovery from sevoflurane anaesthesia.	45
2018	USA	Prospective RCT	8 male patients	15 mg/kg IV caffeine is able to accelerate emergence from isoflurane anaesthesia in healthy males without any apparent adverse effects	43
2018	USA	Retrospective observational	151 heavily sedated patients in the post-anaesthesia recovery area	Median of 150 mg IV caffeine may enhance the speed of recovery following general anaesthesia without any respiratory or cardiovascular changes	44
Safety and changes associated with caffeine administration
1996	USA	Prospective survey	882 nurses surveyed	85% of responders would withhold caffeine in patients after an acute myocardial infarction as a part of coronary precautions	35
2013	USA	Prospective RCT	30 patients	Ingestion of 102 mg of caffeine (drip coffee) can increase spontaneous voiding post indwelling bladder catheter removal	36
2013	USA	Prospective RCT	62 patients	500 mg IV caffeine given intraoperatively resulted in increased nausea, and there was no difference in postoperative headache, fatigue, time to discharge	37
2018	France	Prospective RCT	110 patients booked for heart valve surgery	400 mg caffeine q8h does not affect postoperative AF but does increase the risk of nausea and vomiting	38