Pros and Cons Cricoid Pressure

Pros- Dr Pius Kurian M

Armed Forces Hospital Muscat

Introduction Sellick (Sellick BA. Lancet 1961;2:404; Sellick BA

Cricoid pressure to prevent aspiration Proceedings of the First European Congress of

Anaesthesiology, Vienna 1962;1:89) Gastric inflation during mask ventillation

Cricoid pressure became essential part of Rapid Sequence of Induction and Intubation RSII

IntroductionRecommendation by Sellick in the

abovementioned papers received worldwide acceptance inspite of its technical, clinical and statistical pitfalls(Grade D Level of Evidence )

Probablya)M & M from aspiration was at peak at the

time of its introductionb)Statistical methods were not as

meticulous ,as of nowc)Medicolegal pressures

Introduction Its wide acceptance in anaesthetic and

emergency medicine is reflected in a Review article by Brinacombe Canadian Journal of Anaesthesia 1997;44:414-25

Merits and demerits discussed in indepth detail

Controversya)Jackson S H Anaesthesiology 1996;84:751-2

questioned its scientific validity

b)Tournadre et al Anaesthesiology:1997:86:7-9 Effect of Cricoid Pressure on Lower Oesophageal Sphincter tone -Efficacy

HistoryMention of Cricoid pressure is found in medical

literature 230 years back-Its use in prevention of regurgitation in drowning and prevention of gastric inflation during mask ventillation

Anaesthesia Analgesia 1974;53:230-2It is inconceivable that a maneuver effective in

preventing gastric inflation during manual ventilation would not be effective in preventing esophageal contents from reaching the pharynx

Still a Controversya)Randomised Clinical Trials-almost impossible

due to ethical reasonsb)With low incidence of aspiration studies to

yield significant results will need huge numbers in the both the studygroups

c)Legal pressures-Emergency intubations without cricoid pressure are considered to be substandard care by legal and medical insurance practices

Controversial PointsSpecific areas of debatea)Effectiveness b)Physiology- Loss of LES tonec)Anatomy-Is it possible to occlude alimentary

tract by CPd)Reports of failuree)Complication like nausea,vomiting,and even

oesophageal rupturef)Interfere with airway Management

Controversial Point –a)EfficacyPractice of CP was accepted without proper clinical

statistical and technical evidencePros- Most evidence come from effect of Cricoid

pressure on oesphageal pressure in cadavers and gastric insufflation during mask ventillation in anaesthetised patients

Some studies from cadaveric studies(clinical workshop)

a)Fanning Anaesthesiology Fanning ;1970:32:553-5 b)Salem et al Anaesthesiology 1985:63:443-6

demonstratedCP was effective against 100 cm H2o

Controversial point a)Efficacy Pros Some studies come from effect of CP in

preventing gastric inflation in anaesthetised patients with and without Cricoid Pressure/NMBD

Moynihan RJ Anesthesiology 1993;78:652–6 (paediatrics)

Lawes EG, et al Br J Anaesth 1987; 59:315–8 in adults

Controversial point b)Physiology-Loss of LES toneIt is a fact that LES tone is reduced by

GA/drugs/Cricoid Pressure hence fall in barrier pressure

ProsIdea of CP is not to prevent regurgitation but to

prevent entry into the pharynx.

Controversial point c)-AnatomyOesophageal position is variable in relation to

cricoid hence cannot compress Alimentary tract

ProsRice MJ et al Cricoid pressure results in

compression of thepostcricoid hypopharynx: the esophageal position is irrelevant.MRI imaging on awake volunteers with and without cricoid pressure Anaesthesiology 2009;109:1546-1552

MRI imaging with and without CP Sniffing positiona)Without CPb)With CPc)Compression in a laterally moved postcricoid hypopharynx with compressiond)Patent Oesophagus lumen at point 2 cm inferior to Cricoid

Post cricoid hypopharynx/hypopharyngeus/upper oesophageal sphincter moves along with Cricoid , as a unit irrespective of oesophageal position and compress the alimentary tract

Controversial point c)AnatomyProsConcept of Hypopharynx and Upper

Oesophageal Sphincter was earlier suggested and pressures measured by Vanner R G Anaesthesia 1992;47:95–100

He demonstrated that UES tone is affected by induction of GA and CP augments the UES tone

Controversial Point d)FailuresCons-Regurg aspiration occurs despite CP

Schwartz et al Anaesthesiology;1995:82;376-76.Postintubation infiltrates seen in 4%

J Clin Anesth 1995;7:297–305 Vanner RG, Asai T. Safe use of cricoid pressure.

Controversial Point d)Failures ProsAnaesthesia1999;54:1–3 Herman NL, Carter B,

Van Decar TK. Cricoid pressure: teaching the recommended

level. Anesth Analg 1996;83:859–63Above two surveys indicates that Cricoid

Pressure practical theorotical knowledge is far from satisfactory hence reason for failures.Also stress on periodic asessment trainning which is proven to improve the performance

Controversial point- e) Complications like Nausea Vomiting Oesophageal rupture

ProsNo medical intervention is devoid of

complications especially if protocol is violated

Too little pressure do not protect and too high pressure brings in unwanted effects like retching active vomiting.Again highlights inadequacy in correct application of Cricoid pressure

Controversial point-Interferes with airway managmentConsCompromise airway patency-Excess pressures

can lead to Cricoid /laryaneal patencyCompromise glottic view Interfere with easy use of supraglottic devices

and ETT advancementProsTurgeon et al Anaesthesiology 2005;102:315-

19 CP doesnot increase rate of failed intubations

N/G Tube in situThere has been studies in cadavers that

presence of NG tubes do not interfere with sphincter integrity and can be kept open to the atmosphere

There is no need to avoid mask ventillation contrary to Sellicks teachings especially in certain case where preO2 was inadequte,high O2 consumption,Nondepolariser is used

It is justified in releasing CP in cant intubate cant ventillate situations

Evidence base for CP?Before summarising few points on RSI

evidence base by David Nellipovitz Can J of Anaesthesia 2007;54:9-748 ,in which he used-

Ovid Therapy ie software for detection of quality of literature-163 RCT ‘s of which 18 were nonpharmacological interventions in RSII

Evidence base for CPRole of CP in reducing aspiration is unavailableDue to potential of difficult airway, use is

advised only in high risk patients.Grade D recommendation

Partial or complete release is justified if CP interferes with bag mask/ETT

15-20 cm H20 presure mask ventillation recommended as Grade C

Summarya)CP has still a place emergency intubation-should identify

when to avoidb)CP is not substitute for loss of LES tone but to reinforce

lost UES tonec)Decision to Sellick-balance potential benefits and

potential complicationsd)CP is complex and trainning,periodic asessment,practice

is essential for proper application-Is it possible to train all concerned to ideal levels?

e)Is a valid RCT to prove efficacy of CP in prevention of aspiration likey to happen in near future?

f)Legal /Insurance still considers RSII without CP as substandard

ReferencesDavid Nellipovitz-CAN J ANESTH 2007 / 54:

9 / pp 748–764 Evidence Base for RSIAndranik Ovassapian, MD*Vol. 109, No. 5,

November 2009 Sellick Do or DonotJerrold Lermann November 2009 vol. 109 no.

5 1363-1366 On Cricoid Pressure: “May the Force Be with You

Mohammed El-Orbany; Lois A Connolly Anaesthesia Analgesia May 2010;10:1318 RSII and Current Controversy

Levels of Evidence1a Systematic review (with homogeneity) of randomizedcontrolled trials1b Randomized controlled trials (with narrow confidenceintervals)2a Systematic review (with homogeneity) of cohort studies2b Cohort study or low quality randomized controlled trial3a Systematic review (with homogeneity) of case-controlledstudies3b Case-controlled studies4 Case-series or poor quality cohort and case-controlledstudies5 Expert opinionAdapted from Oxford Centre for Evidence Based Medicine.http://www.cebm.net/levels_of_evidence.asp#notes.

Levels of EvidenceGrade Supporting evidenceA Consistent level 1 studiesB Consistent level 2 or 3 studies, extrapolation from

level 1studiesC Level 4 studies or extrapolation from level 2 or 3

studiesD Level 5 or inconsistent studies at levels 1-4Adapted from Oxford Centre for Evidence Based

Medicine.http://www.cebm.net/levels_of_evidence.asp#notes.