1. Dr David M Levy Consultant Obstetric Anaesthetist Myth or evidence-based practice? Cricoid force is essential to prevent aspiration

2. Cricoid Pressure (CP) Sellick’s 1961 case series Modern imaging –MR –Endoscopy Tracheal intubation –Supraglottic airways Application of CP End-point: aspiration Regurgitation

3. ‘The Lancet’, 1961 BA Sellick, 1918-1996 ME Tunstall, 1928-

4. ‘The Lancet’, 1961 Two notable preliminary communications –Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia BA Sellick, August 19 –The use of a fixed nitrous oxide and oxygen mixture from one cylinder ME Tunstall, 28 October

5. ‘The Lancet’, 1961 Two notable preliminary communications –Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia BA Sellick, August 19 –The use of a fixed nitrous oxide and oxygen mixture from one cylinder ME Tunstall, 28 October

6. Sellick’s case series (1961) No randomisation Position: head-down –Head & neck fully extended ? Induction drug regimen

7. Sellick’s case series (1961) 26 ‘high-risk’ cases 23: no regurgitation after intubation and release of CP 17 laparotomies 3 pyloric stenoses 2 oesophagoscopies 1 forceps delivery 3: regurgitation after intubation and release of CP 1 laparotomy 1 oesophagectomy 1 forceps delivery Sellick BA Lancet 1961; 2: 404-6

8. Sellick’s case series (1961) 26 ‘high-risk’ cases 23: no regurgitation after intubation and release of CP 17 laparotomies 3 pyloric stenoses 2 oesophagoscopies 1 forceps delivery 3: regurgitation after intubation and release of CP 1 laparotomy 1 oesophagectomy 1 forceps delivery Sellick BA Lancet 1961; 2: 404-6

9. Sellick’s case series ? Force applied ? Effect on laryngoscopy/intubation ?  Gastric distension with IPPV –‘pure speculation’ Priebe H-J Seminars in Anesthesia, Perioperative Medicine and Pain 2005; 24: 120-6

10. CP: the downside (primum non nocere) Distortion of airway anatomy –Impediment to Laryngoscopy Tracheal intubation Supraglottic airways Laryngeal trauma Oesophageal rupture  Lower oesophageal sphincter tone –Regurgitation Failure of technique  Failure to –Intubate –Ventilate Priebe H-J Seminars in Anesthesia, Perioperative Medicine and Pain 2005; 24: 120-6

11. 40 years on from Sellick - MR imaging Smith KJ et al Anesthesiology 2003; 99: 60-4

12. CP: view at laryngoscopy ‘…a force close to 30N may cause complete loss of the glottic view’ Haslam, Parker, Duggan Anaesthesia 2005; 60: 41-47

13. Cricoid yoke; view through LMA Force-dependent cricoid deformation –Complete occlusion & airway obstruction at 44N in  50% ♀ at greater risk Palmer & Ball Anaesthesia 2000; 55: 260-8

14. CP: failed intubation Turgeon AF et al Anesthesiology 2005; 102: 315-9

15. CP: failed intubation Failure rate at 30s, Macintosh 3 blade Mean BMI 25, all <35 Mostly Mallampati 1 & 2 Trained assistants –30 N, daily simulation Lateral shift of larynx –43 CP, 9 sham p<0.0001 Failure to intubate –15 CP, 13 sham NS Turgeon AF et al Anesthesiology 2005; 102: 315-9

16. CP: application British Association of Operating Department Assistants n=135 Performance improves with practical training Meek, Gittins, Duggan Anaesthesia 1999; 54: 59-62

17. CP: regurgitation in high-risk patients Methylene blue capsule pre-induction – –Oehlkern L, Anesthesiology 2003; A1235 No CP n=65CPn=65P Induction300.05 Extubation760.7

18. Aspiration : Australian Incident Monitoring Study Anonymous self- reporting –First 5000 incidents 133 cases of aspiration –Majority in elective cases Mostly at induction –Commonest with facemask or LMA CP applied in 11 (8%) Kluger MT, Short TG Anaesthesia 1999; 54: 19-26

19. CP:  incidence of aspiration? Neilipovitz DT, Crosby ET (2007) –No evidence for decreased incidence of aspiration after rapid sequence induction Cricoid pressure –Level 5 evidence (Expert opinion) Grade D recommendation –‘troublingly inconsistent’ or inconclusive studies

20. CP in the ED: risk-benefit analysis ‘We recommend that the removal of CP be an immediate consideration if there is any difficulty intubating or ventilating the ED patient’ Ellis DY et al Ann Emerg Med 2007; 50: 653-65

21. CP: supraglottic airways [1] Proseal™ LMA n = 50 Cricoid pressure impedes –Placement –Ventilation Li et al Anesth Analg 2007; 104: 1195-8

22. LMA Supreme  Verghese C, Ramaswamy B BJA 2008; 101: 404-10

23. CP: supraglottic airways [2] Laryngeal tube (-suction II) n = 40 Cricoid pressure impedes –Placement –Ventilation Asai et al BJA 2007; 99: 282-5

24. Emergency abdominal surgery Fabregat-López et al: Proseal™ LMA –No cricoid pressure –No complications Controversial – –Editorial: Pandit 2008; 63: 967

25. CP – current opinion Koerber et al: Variation in RSI techniques –current practice in Wales 5 scenarios; % who would intubate trachea without CP –Appendicectomy 5% –Symptomatic hiatus hernia 11% –Asymptomatic hiatus hernia 12% –Elective C Section 2% –Bowel obstruction 1% 2009; 64: 54

26. Conclusion Cricoid pressure in RSI - what’s the evidence base?

27. Conclusion ‘Must weigh efficacy in preventing aspiration against risk of impeding tracheal intubation/ventilation’ Turgeon et al 2005 ‘By today’s standards, cricoid pressure can hardly be considered an evidence- based practice’. Priebe 2005

28. A personal view… ~30° head-up position Precalculated doses –Induction agent –Rocuronium Forget CP –Little faith in correct application –Don’t provoke emesis Priority = Optimal conditions for successful airway management May the (cricoid) force be with you?

29. Questions... dmlevy@nhs.net