Table 2.

Summary of studies assessing aspiration events in relation to NPO status.

Author, year [reference number] Study design, sample size NPO status groups (1 = intervention; 2 = control)	Aspiration
	NPO group 1	NPO group 2
Gurudu et al., 2010 [29]	No episodes of bronchoaspiration were recorded, including in the procedures performed in patients taking same-day bowel preparation
Observational: n = 1,345
NPO status 1: ≥4 hours
NPO status 2: >8 hours
Huffman et al., 2010 [31]	None of the patients in any group had clinical evidence of aspiration during their procedures
Observational: n = 301
NPO status 1: ≥2 hours
NPO status 2: >8 hours
Manno et al., 2012 [41]	No major complications related to sedation
RCT: n = 336
NPO status 1: 2 hours
NPO status 2: >8 hours
Mathus-Vliegen and van der Vliet, 2013 [43]	No events during 30-day period (from charts of patients and a complication database)
RCT: n = 188 analyzed
NPO status 1: hours unclear (split-dose exam (p.m.))
NPO status 2: >8 hours
Matro et al. 2010 [44]	1.6% (1/61) were aspirated during the procedure	0/54
RCT, n = 115 analyzed
NPO status 1: 4 hours (a.m. prep only)
NPO status 2: 4 hours (p.m./a.m. prep)
Varughese et al., 2010 [52]	No sedation complications
RCT: n = 136
NPO status 1: ≥3 hours
NPO status 2: >8 hours

NPO: nil per os; RCT: randomized controlled trial.