Suction Catheter Size: An Assessment and Comparison of 3 Different Calculation Methods

• DOI: 10.4187/respcare.02168
• Publication Date: 2013-06-19T01:23:20Z
• Authors: Christopher J Rus...; Joshua F Gonzales; Nicholas R Henry
• Keywords: 03 medical and health sciences; Catheters; 0302 clinical medicine; Practice Guidelines as Topic; Intubation, Intratracheal; Pressure; Humans; Mathematical Concepts; Suction; Respiration, Artificial

Current American Association for Respiratory Care (AARC) clinical practice guidelines recommend a suction catheter to endotracheal tube ratio (SC/ETT) based on the external diameter of the SC and the internal diameter of the ETT. An SC/ETT ratio of < 50% is consistent with the current recommendation. We theorized that a more satisfactory assessment of SC/ETT ratio could be accomplished using volume or area formulas and expansion of diameter recommendations. Some respiratory care texts recommend an SC/ETT ratio that exceeds the clinical practice guideline standard.We calculated the internal volume and cross-sectional area of various ETT sizes, the external volume and cross-sectional area of various SC sizes, and the SC/ETT ratios. We also measured negative pressures created by suction in a lung model, during multiple suction maneuvers.Volume and area calculations provide an alternative method for determining the SC/ETT ratio. A volume or area ratio of 50% corresponds to a diameter ratio of 70%. Negative pressures during suctioning remain low at the new ratios, so a larger SC than current clinical practice guidelines still allows adequate air passage between the SC and ETT.Our results support an alternative SC/ETT ratio when pairing SCs and ETTs.