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.

Table 2 Summary of studies comparing the type of insufflation in endoscopic retrograde cholangiopancreatography

Ref.	Patients (n)	Exclusion criteria	Sedation	Findings
Bretthauer et al[29], 2007	118	COPD with known CO2 retention	Moderate	Less pain up to 24 h in CO2 group
				Increased TCCO2 equally in both groups while under sedation
Maple et al[39], 2009	105	COPD, pre-procedure abdominal pain	Deep	Less pain at 1 h CO2 group, no difference at 24 h
Dellon et al[30], 2010	78	COPD on home O2, known CO2 retention or opiate use	Moderate	Fewer adverse events in CO2 group
				No difference in pain scores
				Increased TCCO2 equally in both groups while under sedation
Kuwatani et al[40], 2011	80	COPD, pre-procedure abdominal pain	Deep	No difference in pain scores
Luigiano et al[31], 2011	110	COPD, pre-procedure abdominal pain	General anaesthesia	Less pain at 1, 3 and 6 h in CO2 group, no difference at 24 h
				Higher TCCO2 in CO2 group but easily compensated for with hyperventilation
Muraki et al[23], 2012	208	COPD	Deep	Less evidence of physiological stress in CO2 group
				Borderline lower complications in CO2 group

COPD: Chronic obstructive pulmonary disease; CO₂: Carbon dioxide; TCCO₂: Transcutaneous carbon dioxide.