Thursday, February 21, 2019


Q: If rapid shallow breathing index (RSBI) is measured on T-piece instead of keeping a patient attached to ventilator, it will be? (select one)

A) higher
B) lower

Answer: A

RSBI tends to record a lower measurement if it is performed while patient stays attached to ventilator. This may be due to the fact that ventilator may underestimate the patient's inspiratory efforts that are not sensed by the ventilator known as 'untriggered breaths'. These unmeasured inspiratory efforts falsely lower the RSBI. The best way to mitigate this effect is to use a pressure support (PS)  of 0 cm H2O and a positive end-expiratory pressure (PEEP) of 0 cm H2O, without flow trigger. Other frequently ignored factors in ICU while measuring RSBI are narrow endotracheal tube, supine position, and very recent suctioning.



1. El-Khatib MF, Zeineldine SM, Jamaleddine GW. Effect of pressure support ventilation and positive end expiratory pressure on the rapid shallow breathing index in intensive care unit patients. Intensive Care Med 2008; 34:505. 

2. Patel KN, Ganatra KD, Bates JH, Young MP. Variation in the rapid shallow breathing index associated with common measurement techniques and conditions. Respir Care 2009; 54:1462. 

3. Kheir F, Myers L, Desai NR, Simeone F. The effect of flow trigger on rapid shallow breathing index measured through the ventilator. J Intensive Care Med 2015; 30:103.

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