I was taught a useful principle by a paediatric anaesthetist 10 years ago which has proven true in my experience and has contributed to keeping me calm when intubating sick kids. Unlike adults, in whom difficulty in intubation can often be unexpected, the vast majority of normal looking children are easy to intubate, and the ones who are difficult usually have obvious indicators such as dysmorphism.
This appears to be supported by recent evidence: in a large retrospective series of 11.219 anaesthesia patients, the overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was only 1.35%, although was much higher in infants less than one year compared with older children. This low percentage is in the same ball park as two other paediatric studies. Besides younger age, their database suggested underweight, ASA III and IV physical status and, if obtainable, Mallampati III and IV findings as predictors for difficult laryngoscopy. The authors point out:
“…the oromaxillofacial surgery department with a high proportion of cleft palate interventions and pediatric cardiac surgery contributed substantially to the total number of difficult laryngoscopies. In patients undergoing pediatric cardiac surgery, a possible explanation for the higher incidence of CML III/IV findings might be that some congenital heart defects are associated with chromosomal anomalies like microdeletion 22q11.2 syndrome. This syndrome is also associated with extracardiac anomalies like cranio-facial dysmorphism“
Take home message: As a very rough rule of thumb to illustrate the difference between the ease/difficulty of laryngoscopy between adults and kids, I think it’s fair to say grade III or IV views occur in about 10% of adults but only about 1% of children.
Incidence and predictors of difficult laryngoscopy in 11.219 pediatric anesthesia procedures
Paediatr Anaesth. 2012 Aug;22(8):729-36
OBJECTIVE: Difficult laryngoscopy in pediatric patients undergoing anesthesia.
AIM: This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation.
BACKGROUND: Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described.
METHODS: Retrospectively, from a 5-year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age-adapted Macintosh blades in a single center (university hospital) were analyzed statistically.
RESULTS: The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P < 0.05) with difficult laryngoscopy. Patients undergoing oromaxillofacial surgery and cardiac surgery showed a significantly higher rate of CML III/IV findings.
CONCLUSION: The general incidence of difficult laryngoscopy in pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates.