The impact of cricoid pressure on oesophagus position and compressibility in Malaysian patients: A prevalence study / Aaron Wilson
Background Cricoid pressure (CP) is an airway manoeuvre used during rapid sequence induction to reduce the risk of pulmonary aspiration. Classically it was thought that CP was effective for this as it compressed onto the oesophagus located centrally. However, anatomical studies involving CP show...
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| Format: | Thesis |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://studentsrepo.um.edu.my/11587/4/aaron.pdf http://studentsrepo.um.edu.my/11587/ |
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| Summary: | Background
Cricoid pressure (CP) is an airway manoeuvre used during rapid sequence induction to
reduce the risk of pulmonary aspiration. Classically it was thought that CP was effective
for this as it compressed onto the oesophagus located centrally. However, anatomical
studies involving CP showed various relative oesophagus positions with variable
degrees of compressibility, and ultrasound is a non-invasive tool that could be used to
assess these parameters.
Purpose:
To determine the sonographic prevalence of relative position of oesophagus to cricoid
cartilage in patients undergoing general anaesthesia; and to assess the qualitative impact
of CP on change of oesophagus position and its compressibility.
Methods
A prospective, cross-sectional study was performed on patients would undergo general
anaesthesia for elective surgery in single tertiary centre in Malaysia. Written consent
obtained from all eligible patients. Prior to induction of general anaesthesia, baseline
ultrasound scan of the neck to assess the position of oesophagus relative to cricoid
cartilage was done and designated as either: central, partially lateral, or completely
lateral. Scan was repeated post general anaesthesia and pre CP. Then CP force of 30N
was applied on cricoid cartilage. Patient’s sonogram was assigned to one of three
groups: directly behind the trachea (“central”), partially behind trachea (“partial”), or
completely lateral to the trachea (“lateral”). Oesophagus was assumed “central” (and
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compressible) if scan did not detect oesophagus; “partial”, if the entire tubular structure
of the oesophagus located behind cricoid cartilage was not visualised (lateral borders of
cricoid cartilage and the oesophagus overlapped); and “central”, if there lateral border
of the two structures overlapped. The position and compressibility of oesophagus were
recorded. Two investigators with fixed roles were involved in obtaining the data,
whereby one applied CP and the other performed the ultrasound scan of the neck. Chi
square test, McNemar or Fisher exact was performed for statistical analysis (α = 0.05).
Results
There were 50 patients recruited. Results pre vs post general anaesthesia were as follow:
44% (vs 34%) patients with central oesophagus, 42% (vs 44%) were partial and 14%
(vs 22%) lateral. The effect of general anaesthesia on oesophagus placement was
significant (p = 0.046). There is no change in oesophagus position pre and post CP.
There was higher prevalence (54%) of oesophagus occlusion with CP in the central and
partial groups (p <0.001). No oesophagus occlusion seen in lateral group.
Conclusions
There was more non-centrally located oesophagus compared to central oesophagus.
Anaesthesia effect has an association with further displacing the oesophagus.
Oesophagus occlusion was less likely if it is deviated from cricoid cartilage. |
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