We would like to report on an observational study we recently undertook in our tertiary referral paediatric hospital in the North of Scotland, UK. Our aims were to assess the ability of anaesthetic personnel to locate the cricoid cartilage in preschool children and infants.
Our local ethics committee (North of Scotland Research Ethics Committee) classified this study as an audit of clinical practice not requiring written patient or parental consent. However, information about the study was given preoperatively and verbal consent obtained.
Patients aged 0 to 6 years requiring general anaesthesia for elective procedures were studied. Monitoring and induction of general anaesthesia were left to the discretion of the attending anaesthetist. An experienced anaesthetist or senior anaesthetic assistant was asked to identify the cricoid cartilage and mark its position in the midline with a washable marker pen. A linear ultrasound probe (Sonosite), SonoSite Ltd., London, UK, was used to determine the actual location of the cricoid cartilage, its maximum width and the distance from the middle of the cricoid cartilage to the skin mark in the midline. Data analysis was performed using the Mann–Whitney U-test and Pearson correlation.
We collected data from 30 patients with a mean (± SD) age of 25.4 (±15.6) months and a mean (± SD) weight of 12.3 (±3.9) kg, with a sex ratio of 2 : 1 (male/female). Twenty-one (70%) of the identifications were performed by a senior anaesthetic assistant. The majority of identifications were made on the initial attempt (83%), with only five identifications requiring a second or third attempt. Comparing these identifications with the measurements made by ultrasound, the mean (± SD) width of cricoid cartilage was 2.5 (±0.9) mm and the mean distance from the cricoid was 5.8 (±2.9) mm for anaesthetists and 4.7 (±3.8) mm for anaesthetic assistants (P = 0.22).
The mean (± SD) width of the cricoid cartilage and mean measured distance by ultrasound for children aged 12 months or less was 2.5 (±0.66) and 4.9 (±3.28). For those children over 12 months old, the mean width was 2.6 (±0.95) and 5.0 (±3.81) (See Table 1). There were no statistically significant differences in the measured distances between the two age groups (P = 0.49).
Our study demonstrates that correct identification of the cricoid cartilage in young children is difficult using surface landmarks only. In all but one patient, there was a measurable difference found between where the cricoid was thought to be, and where it was actually visualised using ultrasound. Despite these differences being small and in the majority of cases readily covered by the breadth of the fingertip used to apply cricoid pressure, the results of this study once again raise the question of the value of cricoid pressure in rapid sequence induction in young children. Interestingly, there were no age-dependent differences in these preschool children, with no statistically significant differences between those patients over and under 12 months of age.
Our results indicate that the operating department practitioners and nurse anaesthetists were equally successful at identifying the cricoid cartilage as senior anaesthetists. Lack of exposure to performing cricoid pressure does not lead to less skill in identifying the cricoid cartilage correctly.
The incorrect application of cricoid pressure has the potential to cause harm, by hindering laryngoscopy and causing difficulties with tracheal intubation. However, imaging the necks of children who are at risk of aspiration prior to general anaesthesia may not always be feasible. The potential aspiration risk in children appears to be very low and occurs despite the recorded application of cricoid pressure.1 Rapid sequence induction of anaesthesia in small children may lead to iatrogenic hypoxia, bradycardia and hypotension.2 Controlled bag-mask ventilation without application of cricoid pressure in children considered at risk of aspiration may be considered as a suitable alternative, to prevent such occurrences.
The effectiveness of cricoid pressure during rapid sequence induction in children has long been questioned. However, it does have use as a landmark for emergency airway access. A large retrospective American study1 surveying over 60 000 paediatric patients undergoing general anaesthesia reported a 0.04% incidence of pulmonary aspiration. Seventeen out of the 24 patients who suffered aspiration were emergency cases and all had application of cricoid pressure. In a separate survey of paediatric anaesthetists, only 68% admitted using cricoid pressure when traditionally indicated.2
If indeed the use of cricoid pressure is deemed protective, then the second issue in this population relates to the accuracy of the localisation of the cricoid cartilage. The incorrect application of pressure on the cricoid, or other cartilaginous structures (in error) of the upper airway, could lead to structural damage as well as causing airway obstruction and difficulty at laryngoscopy.3
Accurately locating the cricoid cartilage in small children is difficult. Whether this has clinically significant consequences remains to be elucidated, but we believe that our study adds to the ongoing debate over the value of cricoid pressure in the paediatric population.
Acknowledgements relating to this article
Assistance with the study: we would like to thank the theatre staff of the Royal Aberdeen Children's Hospital for their assistance and cooperation with this study.
Financial support and sponsorship: none.
Conflicts of interest: none.
1. Warner MA, Warner ME, Warner DO, et al. Pulmonary aspiration in infants and children. Anesthesiology
2. Ahmed Z, Zestos M, Chidiac E, et al. A survey of cricoid pressure use among pediatric anesthesiologists. Pediatric Anesthesia
3. Landsman I. Cricoid pressure: indications and complications. Pediatr Anaesth