Dr David M Levy Consultant Obstetric Anaesthetist

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

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

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 mixturefrom 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 mixturefrom 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) Sellick BA Lancet 1961; 2: 404-6

8. Sellick’s case series (1961) 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 Pain2005; 24: 120-6

10. 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 CP: the downside (primum non nocere) Priebe H-J Seminars in Anesthesia, Perioperative Medicine and Pain2005; 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 & BallAnaesthesia 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

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 pressureimpedes • Placement • Ventilation Li et alAnesth Analg 2007;104: 1195-8

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

23. CP: supraglottic airways [2] • Laryngeal tube(-suction II) • n = 40 • Cricoid pressureimpedes • Placement • Ventilation Asai et alBJA 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 • Cricoid pressure in RSI - what’s the evidence base? • ‘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 successfulairway management May the (cricoid) force be with you?

29. Questions... dmlevy@nhs.net