Carbon dioxide insufflation for endoscopic retrograde cholangiopancreatography: A meta-analysis and systematic review

Table 1 Search strategies

Databases	Period of search	Search strategies
The Cochrane library	Until 1st December 2011	1. MeSH descriptor Cholangiopancreatography, Endoscopic Retrograde explode all trees
		2. (endoscopic retrograde cholangiopancreatograph*): ti, ab, kw OR (ERCP): ti, ab, kw
		3. MeSH descriptor Carbon Dioxide explode all trees
		4. (carbon dioxide): ti, ab, kw OR (CO2): ti, ab, kw
		5. 1 OR 2
		6. 3 OR 4
		7. 5 AND 6
MEDLINE via PubMed	Until 1st December 2011	1. “Cholangiopancreatography, Endoscopic Retrograde” [MeSH] OR endoscopic retrograde cholangiopancreatograph* [tiab] OR ERCP [tiab]
		2. “Carbon Dioxide” [Mesh] OR carbon dioxide [tiab] OR CO2 [tiab]
		3. 1 AND 2
EMBASE via embase.com	Until 1st December 2011	1. ‘endoscopic retrograde cholangiopancreatography’/exp OR ‘endoscopic retrograde cholangiopancreatography’
		2. ‘ercp’/exp OR ercp
		3. ‘carbon dioxide’/exp OR ‘carbon dioxide’
		4. ‘CO2’/exp OR CO2
		5. 1 OR 2
		6. 3 OR 4
		7. 5 AND 6
Science citation index expanded	Until 1st December 2011	1. TS = (‘endoscopic retrograde cholangiopancreatograph*’ OR ERCP)
		2. TS = (‘carbon dioxide’ OR CO2)
		3. 1 AND 2
CBM	Until 1st December 2011	Search strategy in Chinese. Includes search terms similar to the terms used in MEDLINE

MEDLINE: Medical Literature Analysis and Retrieval System Online; EMBASE: Excerpta Medica Database; CBM: Chinese Biomedical Literature Database; MeSH: Medical Subject Heading; ERCP: Endoscopic retrograde cholangiopancreatography.

Table 2 Study characteristics

Author	Year	Country	Study design	Participants	Participants (CO2/Air)	Mean age (CO2/Air)
Bretthauer et al[8]	2007	Norway	Multi-centers	Low risk	118 (58/58)	57/54
Maple et al[12]	2009	United States	Single-center	Low risk	105 (50/50)	57/51.7
Dellon et al[9]	2010	United States	Single-center	High risk and low risk	78 (36/38)	60.1/59.7
Kuwatani et al[10]	2011	Japan	Multi-centers	Low risk	80 (40/40)	66.1/68.7
Luigiano et al[11]	2011	Italy	Single-center	Low risk	78 (39/37)	66.1/67.1
Mei et al[13]	2011	Australia	Single-center	Not mentioned	61 (34/27)	Not mentioned
Arjunan et al[14]	2011	India	Single-center	Low risk	298 (147/151)	Not mentioned

Low risk refers to patients without chronic obstructive pulmonary diseases; high risk refers to patients with chronic obstructive pulmonary diseases.

Table 3 Risk of bias in included trials

Studies	Sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting
Bretthauer et al[8]	Low risk	Low risk	Low risk	Low risk	High risk	High risk
Maple et al[12]	Low risk	Low risk	Low risk	Low risk	High risk	High risk
Dellon et al[9]	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Kuwatani et al[10]	Low risk	Unclear risk	Low risk	Low risk	Low risk	High risk
Luigiano et al[11]	Low risk	Low risk	Low risk	Low risk	High risk	High risk
Mei et al[13]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	Unclear risk
Arjunan et al[14]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	Unclear risk