Is the type of insufflation a key issue in gastro-intestinal endoscopy?

Table 1 Studies comparing carbon dioxide and air insufflation in colonoscopy

Ref.	Patients (n)	Exclusion criteria	Sedation	Findings
Stevenson et al[11], 1992	56	Previous colonic resections, children	Moderate	No difference in pain during procedure but better in CO2 group at 6 and 24 h post
				AXR at 1 h - 94% trace/v little gas in CO2 group, air 18% > 10 cm, 57% > 6 cm
Sumanac et al[7], 2002	100	GI bleed, IBD, colectomy	Moderate	AXR at 1 h - 71% > 6 cm in air vs 4% in CO2 group
				Reduced pain score at 1 and 6 h in CO2 group
Bretthauer et al[16], 2002	240	Previous resection, malignancy, severe cardiac or respiratory disease	None	Lower pain score at all time points in CO2 group
				No difference in ETCO2
Church et al[33], 2003	247	None	Moderate	Lower pain score 10 min post procedure in CO2 group but no difference during
Bretthauer et al[34], 2005	103	Severe COPD, children	Moderate /none	Lower pain in CO2 group at 1, 3, and 6 h
				Higher ETCO2 in both groups when sedated
Wong et al[12], 2008	96	COPD, colectomy, bleeding, obstruction	Moderate	Lower pain score in CO2 group during procedure and in first 30 min then no difference
				93% CO2vs 98% air would have procedure again 89% CO2vs 96% air would recommend to others
Liu et al[35], 2009	349	None	None	Lower pain score in CO2 group
				No difference in ETCO2
Riss et al[5], 2009	300	Severe COPD, children	Deep	Lower pain score in CO2 group at 15 m, 30 m and 6 h but not during procedure
				98% overall would have procedure again, no difference between groups
Geyer et al[17], 2011	109	None	Moderate/deep	Less pain and bloating (peak at 1 h) in CO2 group
				No change in TCCO2
Yamano et al[27], 2010	120	Previous resection, malignancy, severe cardiac or respiratory disease, active bleeding, obstuction	None	Lower pain score in CO2 group
Mayr et al[36], 2012	156	None	Moderate	No rise in TCCO2
				No pain in 84% of CO2 group vs 65% of air group
Singh et al[6], 2012	142	Previous resection	Deep	Higher caecal intubation rate and faster in CO2 group
				Less discomfort in CO2 group
Díez-Redondo et al[37], 2012	282	None	Moderate/deep	Reduced pain scores in CO2 group for first 6 h
Chen et al[18], 2013	193	None	None	No difference in VAS
Iida et al[15], 2013	100	None	Moderate	Reduced salivary stress hormones in CO2 group
				No difference in VAS score
Uraoka et al[38], 2009	114	Easy colonoscopies	None	Overall lower pain in CO2 group, particularly when done by less experienced endoscopists
Fernández-Calderón et al[13], 2012	214	None	Deep	Lower pain in CO2 group
				Greater increase in waist circumference in air group
Seo et al[14], 2013	94	None	Moderate	Less pain in CO2 group
				Greater increase in waist circumference in air group

CO₂: Carbon dioxide; AXR: Abdominal radiograph; GI: Gastrointestinal; IBD: Inflammatory bowel disease; ETCO₂: End-tidal carbon dioxide; COPD: Chronic obstructive pulmonary disease; TCCO₂: Transcutaneous carbon dioxide; VAS: Visual analogue score.