TRACHEAL TUBE LEAK TEST - IS THERE INTEROBSERVER AGREEMENT

Although the leak test is recommended as a method of assessing the app ropriate size of uncuffed endotracheal tubes for use in children, the reproducibility of this test has not been validated. Patients from new born to ten years of age requiring tracheal intubation for elective su rgery were studied. The endotracheal tube size was calculated using th e formula. (age + 16) divided-by 4 for patients greater-than-or-equal- to two years of age and at the discretion of the attending anaesthetis t for patients < two years of age. After the induction of anaesthesia and administration of a non-depolarizing muscle relaxant, the patient' s trachea was intubated and mid-tracheal placement was confirmed. Two of the three staff anaesthetists participating in the study assessed t he leak pressure consecutively. Each participant performed a single le ak determination The kale pressure was determined as follows: the pati ent was supine with the head in a neutral position, fresh gas flowed i nto the breathing circuit at 5 L . min-1, a stethoscope was placed on the skin over the larynx and the pressure relief valve was completely closed. Pressure slowly increased in the breathing circuit until an au dible leak occurred around the tracheal tube. The inter-observer diffe rence was calculated in 212 patients. The absolute value of the differ ence between that of two observers increased as the mean leak pressure increased. However, the variation between observers expressed as a pe rcent of the absolute measurement remained constant. An average varian ce in measurement of 38% was found al both low and high kak pressures. In conclusion, we found considerable variation between two experience d observers in assessing leak pressures As the leak pressures increase , the difference between these observations also increases. Therefore, we believe it is unreasonable to set an upper limit of leak pressure for changing all endotracheal tubes.