The Association between Thenar Eminence and I-gel Dimensions in Paediatric Patients

After obtaining local research ethical committee approval, two hundred and seventy ASA Class I or II patients between 0 to 12 years old, who were scheduled for elective surgery under general anaesthesia not requiring tracheal intubation were recruited to the study. Written informed consent was taken from the parents. Children with risk factors for difficult airway or regurgitation and syndrome or disorders influencing bone or soft tissue growth were excluded. Patients in the operating room were monitored for standard electrocardiography (ECG), blood pressure non invasively and peripheral oxygen saturation (SpO2). After preoxygenation, anaesthesia induction was performed with 8% sevoflurane in 50% nitrous oxide and oxygen, followed by intravenous access and administration of fentanyl 1 micro.kg-1. No muscle relaxants were used. Adequate anaesthetic depth was confirmed by lack of a motor response to jaw thrust. The i-gel is a novel supraglottic airway management device, made of a medical grade thermoplastic elastomer, which is soft, gel-like and transparent. Its non-inflatable cuff fits snugly onto the perilaryngeal framework. The size of the I-gel selected was based on the patient’s body weight according to the manufacturer recommendation . (size 1: 2-5 kg, size 1.5: 5-12 kg, size 2: 10-25 kg, size 2.5: 25-35 kg). Size 1.5 i-gel was inserted in children weighing 10-12 kg, and if there was an audible leak it was decided to change the size 1.5 to size 2. The device was inserted with “sniffing the morning air” position, and depending upon the airway manipulations (like neck flexion, head extension, jaw thrust, or deep rotation) required to insert the device. Correct insertion was judged by symmetric chest expansion, square wave of the capnograph trace, and absence of audible leak. The number of insertion attempts was noted, and it was considered a failure if the insertion was not successful in three attempts. In this case, patient was intubated, and excluded from the study. After successful insertion of the I-gel, thenar eminence dimensions were determined from left hand while fingers were placed in neutral position. Measurements were performed with a ruler in approximately 15 seconds. Long axis (Th-l) was measured from joining point of thumb to hand crease and short axis (Th-w) constitutes the largest portion of the thenar eminence from lateral end of the thumb to the first vital crease. Width (Ig-w) and length (Ig-l) of the I-gel’s (size 1-1.5-2-2.5) soft non-inflatable cuff was measured. The manufacturer's dimensions of the I-gel which was inserted into the patients were compared with the measurements obtained from thenar eminence.