1. Efficacy of Cricoid Pressure in Preventing Gastric Inflation – A Critical Analysis of the Literature Department of Anesthesiology, Advocate Illinois Masonic Medical Center, Chicago, IL 60657 USA Introduction References Methods M. Ramez Salem, MD, N. Nick Knezevic, MD, PhD, Andre Camara, MD, George J. Crystal, PhD In 1961, Sellick described cricoid pressure (CP) to control regurgitation of gastric or esophageal contents. He also suggested that the same maneuver may be useful in preventing inflation of the stomach during positive-pressure ventilation applied through a face mask. 1 In the subsequent four decades, several studies evaluated the effectiveness of CP in preventing gastric inflation in children and adults. 2-5 If these studies can convincingly demonstrate the effectiveness of the maneuver in preventing gastric inflation, this will imply that CP must also be effective in preventing esophageal contents from reaching the pharynx. We reviewed all articles that addressed the efficacy of CP in preventing gastric inflation since 1974, when the first article was published. 2 Studies which evaluated the effectiveness of the maneuver in preventing gastric inflation during positive-pressure ventilation with the use of laryngeal mask airways (or other airway devices) were excluded. We considered only studies in which the same patients were evaluated with and without CP and which measurements of one or more of the following variables were obtained: gas volume in stomach, exhaled tidal volume, and documented air entry in the stomach (Table). In these studies, cases where gastric inflation without CP did not occur were excluded. Authors and year of publication Number of patients qualified/total Age RangeParametersStudy DesignEfficacy Salem MR, et al. 1974 9/103 months- 5 years - Gas volume in stomach - Peak airway pressure - Exhaled Volumes same patients with and without CP CP effective in all 9 patients Admani M, et al. 1985 10/10premature infants - Gastric gas volumes - Blood gases and pH without and with nasogastric tube and without nasogastric tube with CP CP effective in all 10 infants without nasogastric tube Lawes EG, et al. 1987 9/2016-80 years old - Auscultation - Peak Inspiratory Pressure same patients with and without CP CP effective in 8 out of 9 qualified patients (airway pressure 44.7 cmH 2 O) Moynihan RJ, et al. 1993 59/592 weeks- 8 years - Auscultation - Peak Inspiratory Pressure same patients with and without CP and with and without muscle relaxant CP effective in all 59 patients 1.Sellick BA. Lancet 1961;2:404-6. 2.Salem MR, et al. Anesthesiology 1974;40:96-8. 3.Adamani M, et al. Crit Care Med 1985;13:592-3. 4.Lawes EG, et al. Br J Anaesth 1987;59:315-8. 5. Moynihan RJ, et al. Anesthesiology 1993;78:652-6. All the published studies that we uncovered found CP to be a useful technique in preventing gastric inflation during mask ventilation. However, only four of the studies satisfied our criteria for review (3 in infants and children and 1 in adults). 2-5 The total number of patients studied was 99. The 12 patients in whom gastric insufflation did not occur without CP were excluded. In the remaining 87 patients (except one), CP prevented the occurrence of gastric inflation during manual ventilation. One study concluded that “gas does not enter the stomach in any patient with a patent airway when CP was applied, despite inflation pressures exceeding 60 cm H 2 O.” A critical analysis of studies revealed that, in 86 of 87 patients, CP was clearly effective in preventing gastric inflation. It is inconceivable that the maneuver can be effective in preventing gastric inflation during manual ventilation, while not be effective in preventing esophageal contents from reaching the pharynx, should regurgitation occur. Abstract In 1961, Sellick suggested that cricoid pressure (CP) may be useful in preventing inflation of the stomach during positive-pressure ventilation applied through a face mask. We reviewed all articles that addressed the efficacy of CP in preventing gastric inflation since 1974, when the first article was published. The total number of patients studied was 99. The 12 patients in whom gastric insufflation did not occur without CP were excluded. In the remaining 87 patients (except one), CP prevented the occurrence of gastric inflation during manual ventilation. We concluded that, CP was clearly effective in preventing gastric inflation. It is inconceivable that the maneuver can be effective in preventing gastric inflation during manual ventilation, while not be effective in preventing esophageal contents from reaching the pharynx, should regurgitation occur. Results Conclusion