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

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.